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Introduction: In Rx ponder patients with nodal involvement and a recurrence score between 0-25 were randomised to receive either chemotherapy followed by endocrine therapy or endocrine therapy alone. Patients were stratified by recurrence score (RS) 0-13 vs 14-25, menopausal status and type of axillary surgery. 50% of the patients randomised to chemotherapy received TC (4 or 6 cycles) and ovarian function suppression (OFS) was used in 16% in the ET arm and 3% in the chemotherapy plus ET arm (CET). 33% of the patients enrolled were premenopausal. The overall analysis demonstrated that patients with CET had a significantly higher iDFS at 5 years than those with ET (92.4% vs 91%); HR 0.81, p=0.026. There was a significant interaction of menopausal status and chemotherapy. 5-year iDFS was 94.2% with CET and 89% with ET (delta 5.2%); HR 0.54; p=0.0004, which was larger in the group with a RS 13-25. Because the use of OFS in the CET arm was only 3% it was hypothesised that the main effect of chemotherapy is due to ovarian function suppression. Main Part: OFS added to tamoxifen or AI is very effective in premenopausal women as shown by the SOFT and TEXT studies. The majority of women in SOFT and TEXT received chemotherapy and the effect was observed mainly in the group receiving chemotherapy (a surrogacy for high risk). Adding OFS to tamoxifen plus chemotherapy vs chemotherapy plus tamoxifen is better. The LHRH metaanalysis demonstrated that LHRH was about equally effective to chemotherapy. However, the majority of trials used 2 years LHRH, chemotherapy consisted mainly of CMF and the effect was seen in women under 40 years. The subsequent metaanalyses by the EBCTCG support chemotherapy regardless of ET and menopausal status. Anthracycline and taxane containing chemotherapy is more effective than CMF and dose-dense chemotherapy is even more effective than standard chemotherapy. Chemotherapy can induce amenorrhoea and women with chemotherapy induced amenorrhea have a better outcome than those without. Cyclosphosphamide and especially in the CMF regimen have the highest rate of amenorrhea and the main effect is seen in women between 40 and 50 years. Younger women regain menses, so the ovarian function suppression is temporarily, especially in women below 40 years. The dose of cyclophosphamide in the TC regimen, which was predominantly used in Rx-Ponder is lower than in the CMF regimen but similar to modern type chemotherapy regimen. In RX-Ponder the chemotherapy effect was seen in all premenopausal women but there was no difference of the point estimate in women between 40-50 and younger than 40 years of age. The ovarian function suppression effect is transient and women under 40 year of age tend to regain menopause and should receive an LHRH in addition. In very young women the ovarian function suppression with an LHRH analogue is about 80% leaving 20% without adequate OFS. The toxicity rate of 5 years of LHRH containing ET is high and should not be underestimated compared to 4-6 months chemotherapy. Compliance of LHRH is lower than in adjuvant chemotherapy affecting the effectiveness of adjuvant therapy. If LHRH is discontinued at 2years of LHRH the patient will receive only tamoxifen, which is too little in high risk, premenopausal women. The recurrence score mainly measures endocrine sensitivity of the tumour which does not imply chemoresistance. Nodal status remains still the most important prognostic factor and chemotherapy reduces the risk of recurrence by 30-40%.The data from Rx-Ponder are comparable to the data generated in the Mindact trial. In women younger than 50 years being at clinical high risk but with a genomic low risk tumour chemotherapy improved 8-year DDFS to 93.6% compared to 88.6% without chemotherapy (HR 0.54 95%; CI 0.30-0.98).In conclusion: Premenopausal women with node-positive HR+/HER2- breast cancer benefit from the use of chemotherapy in addition to LHRH even if the RS indicates a biological low risk. Citation Format: S Loibl. Con - RxPONDER: Was it all OFS? [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr DEB1-2.

Background: We have previously shown that expression of the IL8/VEGFA-metagene eliminates the good prognostic effect of TILs in TNBC (PMID 21978456, 28750120). We also showed that the VEGFA metagene predicted response to neoadjuvant bevacizumab in the GeparQuinto trial (Karn 2017 SABCS #851166). The main cellular sources of the transcripts that comprise the VEGFA metagene are unknown since mRNA profiling of bulk biopsies contains signals from different cell types. Methods: Individual genes that comprise the VEGFA metagene were measured in bulk tissue- and single cell-RNA-Seq from breast cancer subtypes and normal cells on different platforms (Affymetrix n=4915, Agilent n=597, Illumina n=2433, RNA-Seq n=1215, Exome Capture RNA-Seq n=226, HTG-Seq n=243, sc-RNA-Seq n=24710). For blinded, orthogonal validation we performed immunohistochemistry. Effect of neoadjuvant chemotherapy with or without bevacizumab was studied by RNA-Seq and IHC on samples from GeparQuinto trial. SWOG S0800 (GSE114403), PROMIX (GSE87455), and GeparSixto trials were used for validation. TCGA was mined for mutations and somatic CNA. RNA-Seq from GeparNuevo was used for correlation with checkpoint inhibitor treatment. Results: We identified a stable core of six genes (VEGFA, ANGPTL4, ADM, NDRG1, DDIT4, CSTB) in different cohorts. Strong expression of this signature was mainly restricted to TNBC subtype and associated with poor prognosis within this subgroup. Single cell RNA-Seq of breast epithelial cells from 4 reduction mammoplasties and 4 TNBC revealed that these genes are coexpressed in individual epithelial cells and not associated with endothelial cells. In line with their presumed functions in cellular stress and hypoxia, immunohistochemistry revealed strong para-necrotic expression in TNBC. Moreover, high gene expression in TNBC was associated with mutations in DNA damage control pathways, somatic copy number alterations, and lower TILs. While chemotherapy led to downregulation, bevacizumab increased expression. In multivariate analysis, high pretreatment values predict pCR to both bevacizumab and chemotherapy (OR 2.40, P=0.006), which may be explained by sensitivity of tumors which are already under cellular stress. On the other hand, expression of the VEGFA metagene seems to create an immunosuppressive environment that counteracts the positive prognostic effect of TILs. In pre-treatment biopsies from the GeparNuevo checkpoint inhibitor trial we found a negative correlation of VEGFA metagene expression with the amount of the recently identified tissue-resident memory T cell subset (CD8TRM, PMID 29942092; P=0.002), while the subsequent increase of CD8TRM during treatment was larger in tumors with high VEGFA (P=0.019). Conclusions: Perinecrotic carcinoma cells under stress from hypoxia and or chromosomal instability are the source of the VEGFA metagene signature. Its predictive value in TNBC suggests estimating and reporting the amount of necrosis in the pathology report may be helpful in predicting response to preoperative chemotherapy, and could be used as stratification factor in clinical trials. The signature indicates an immunosuppressive environment and should be further studied in the context of immune therapies in combinations with anti-angiogenic treatment. Citation Format: Karn T, Denkert C, Sinn BV, Weber K, Nekljudova V, Rody A, Meissner T, Hatzis C, El-Balat A, Becker S, Solbach C, Untch M, Schneeweiss A, von Minckwitz G, Loibl S, Pusztai L, Holtrich U. Single-cell profiling identifies hypoxic carcinoma cells as source of an immunosuppressive VEGFA metagene [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-10-01.

Purpose: Endocrine based therapy is an effective strategy to manage hormone receptor-positive, human epidermal growth factor receptor 2-negative (HR+/HER2-) advanced breast cancer (ABC). However, nearly all patients exhibit/develop either de novo or acquired resistance. While prognostic biomarkers of endocrine responsiveness are well established for the adjuvant treatment in ER+ breast cancer, less is known regarding prognostic and predictive biomarkers of response in the first line ABC setting. We sought to develop a clinical calculator based on clinical criteria for predicting progression-free survival (PFS) and overall survival (OS) of women with HR+/HER2- ABC who will be receiving endocrine monotherapy as first-line treatment for ABC. Methods: The development of the clinical calculator will be based on data from modern clinical trials in women with HR+/HER2- ABC. The studies to be included in the final analyses are given in Table 1. The control arm data from trials1-6 will form the training dataset (N = 1,223) and be used to construct the clinical prediction models. Variables considered include age, race, ECOG status, disease measurability, body mass index, disease-free interval, number of metastatic sites, locations of metastatic sites, prior endocrine therapy, and prior chemotherapy. Missing values will be imputed using single imputation with all variables included in the imputation model. For continuous variables, restricted cubic splines will be used to determine if non-linear effects may be more appropriate. The Lasso regression will be used as a variable selection technique to reduce the dimensionality of covariates; initially all pairwise interactions will be included in the model. Following Lasso regression, the multivariable Cox proportional hazards models will be constructed for PFS and OS including only variables retained in Lasso. The final model will be internally validated for discrimination and calibration using 10-fold cross-validation. External validation will be performed using control arm data from EGF 30008 (N = 536). Results: To date, control arm data from four trials (trials 1-4) have been received. The preliminary results presented here are based on pooled data from C40503 and LEA, for which data elements have been harmonized. Models for predicting PFS and OS have good calibration and are associated with bias-corrected C-indices of 0.61 and 0.65, respectively. These models will be updated using pooled data from trials 1-6. Conclusions: Our preliminary data demonstrate that clinical calculators based on baseline clinical factors can provide accurate prediction of PFS and OS in patients with HR+/HER2- ABC treated with first-line ET. If validated, these tools may be used for risk stratification in future clinical trials and to identify patients who may require more or less aggressive therapy. Table 1:Studies to be includedTrial NumberTrial NameTrial PISample Size in Control Arm1C40503Maura Dickler152 (letrozole)2LEAMiguel Martin179 (letrozole)3FACTJonas Bergh188 (anastrozole)4FALCONJohn Robertson194 (anastrozole)5S0226Rita Mehta345 (anastrozole)6MONARCH 3Matthew Goetz165 (nonsteroidal AI)7EGF 30008Stephen Johnston536 (letrozole) Citation Format: Polley M-YC, Dickler MN, Johnston S, Goetz MP, de la Haba J, Loibl S, Mehta RS, Bergh J, Roberston J, Barlow W, Liu H, Tenner K, Martin M. A clinical calculator to predict disease outcomes in women with hormone receptor-positive advanced stage breast cancer treated with first-line endocrine therapy [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-07-05.

Background Even though patients with a pCR following neoadjuvant chemotherapy have an excellent prognosis still some of these patients will eventually relapse. A better identification of pts with an increased risk of relapse despite a pCR would be helpful to select these patients for additional post-neoadjuvant treatment strategies. Thus, the rationale of this retrospective analysis was to identify factors predicting relapse despite a pCR. Methods This pooled retrospective analysis based on the GBG meta-database includes the neoadjuvant trials GeparTrio, GeparQuattro, GeparQuinto, GeparSixto and GeparSepto. In these trials 2188 (27%) of 7933 pts had a pCR according to ypT0/ypTis ypN0 Definition and were included. The primary endpoint was disease-free survival (DFS), secondary endpoints were distant DFS (DDFS) and overall survival (OS). A multivariate Cox proportional hazards model was used to report hazard ratios with 95% confidence interval (CI). The two-sided significance level was set to α=0.05. Endpoints were analysed for all pts and in subgroups defined by intrinsic subtypes. The potential risk factors intrinsic subtype (HER2 negative/hormone receptor (HR) positive, triple negative, HER2 positive/HR positive, HER2 positive/HR negative), histological tumor type (lobular vs other), grade (G1/G2 vs G3), KI67 (≤20% vs higher), initial cT and cN stadium (cT1 vs cT2 vs cT3/4; cN0 vs cN+), age (≤40 vs 41-59 vs ≥60), BMI (< 25 vs 25-29 vs ≥ 30), planned number of cycles of chemotherapy (≤6 vs > 6), menopausal status (pre- vs postmenopausal) and clinical response after 2-4 cycles (SD vs PR vs CR vs PD) were included as covariates in multivariate Cox regression models as well as study identification. Results From 2188 evaluable patients DFS, DDFS and OS events were observed in 290/197/130 pts respectively; the median follow-up over all studies was 59 months. In multivariate analysis including study and all potential risk factors DFS was significantly different with regard to the initial cN status (cN+ vs cN0, hazard ratio (HR) 1.70; 95% CI [1.2, 2.4], p=0.002). Of borderline significance was histological type (non-lobular vs lobular, HR 0.52 95% CI [0.3, 1.1]; p=0.076) and initial tumor stage (cT3/4 vs cT1, HR 1.61 95% CI [1.0, 2.7]; p=0.064). In terms of DDFS significant differences were seen for the initial cN status (cN+ vs cN0, HR 2.34; 95% CI [1.5, 3.6], p Conclusions Initial tumor load before start of neoadjuvant chemotherapy (tumor stage and nodal status) and lobular subtype were predictors of long term outcome after a pCR following neoadjuvant chemotherapy. Intrinsic subtype, KI67, grade and planned number of cycles were not predictive for a relapse. Citation Format: Huober J, Schneeweiss A, Blohmer J-U, Denkert C, Tesch H, Hanusch CA, Salat C, Rhiem K, Rezai M, Solbach C, Fasching PA, Jackisch C, Mehta K, Nekljudova V, Seither F, von Minckwitz G, Loibl S, Untch M. Factors predicting relapse in early breast cancer patients with a pathological complete response after neoadjuvant therapy – Results of a pooled analysis based on the GBG meta-database [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-08-01.

Background: The GeparNuevo trial showed a numerical increase in the pCR rate to 53% vs 44%; p=0.281 compared to placebo in TNBC with the addition of the anti-PD-L1 antibody durvalumab to a neoadjuvant anthracycline-taxane containing chemotherapy (Loibl S et al. ASCO 2018). In a predefined subgroup analysis, a significant increase of the pCR rate was observed for patients that received durvalumab for 2 weeks alone prior to the start of chemotherapy in a window phase (61% vs 41%, p interaction=0.048), while the pCR rate was not increased for the subset of patients that did start durvalumab together with chemotherapy. Here we report the main results of the translational programme for GeparNuevo with a focus on mRNA signatures predictive for pCR in pretherapeutic core biopsies. Methods: A total of 162 baseline FFPE core biopsies were evaluable for expression of 2560 genes using the HTG EdgeSeq® system that combines a modified nuclease protection assay with next generation sequencing. Data was processed as recommended by the HTG and median transformed for further analyses. For differential gene expression analyses, the data was scale-normalized (TMM normalization; EdgeR package) and linear models were fit (limma package). Prior to these analyses, genes were filtered based on minimal expression (> 4) and variability (IQR > 1). As a first step, predefined immune-genes signature (TILs signature) (Denkert et al. JCO 2016) as well as IFN-gamma signatures were evaluated for correlation with pCR in logistic regression models. Subsequently, we performed a differential gene expression analysis according to therapy response for the durvalumab-arm and the placebo arm using the pre-filtered candidate genes. Gene names are not included in this abstract to allow filing of IP, but full gene names will be presented at the SABCS meeting. Results: The predefined TIL- and IFN-gamma signatures were associated with increased pCR rates in the complete cohort (TIL-signature: OR 1.44, 95% CI 1.15-1.82, p=0.002; IFN-Gamma-signature: OR 1.63, 95% CI 1.22-2.24, p=0.002) as well as in the durvalumab arm (p=0.012 and 0.042) and the placebo arm (p=0.050 and 0.011). These signatures were general pCR predictors without specificity for durvalumab response. Additional 44 genes were significantly (p Conclusion: Our results show that specific immune-related gene expression signatures predict response to durvalumab in primary triple negative breast cancer. The trial was financially supported by Astra Zeneca and Celgene Citation Format: Loibl S, Sinn BV, Karn T, Untch M, Treue D, Sinn H-P, Weber KE, Hanusch CA, Fasching PA, Huober J, Zahm D-M, Jackisch C, Thomalla J, Blohmer J-U, Marmé F, Klauschen F, Rhiem K, Felder B, von Minckwitz G, Burchardi N, Schneeweiss A, Denkert C. mRNA signatures predict response to durvalumab therapy in triple negative breast cancer (TNBC)– Results of the translational biomarker programme of the neoadjuvant double-blind placebo controlled GeparNuevo trial [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr PD2-07.

Background: Palbociclib (PAL) in combination with endocrine therapy (ET) is a preferred treatment option for untreated and previously treated patients with hormone receptor–positive (HR+), human epidermal growth factor receptor 2 (HER2)–negative ABC. Patients with bone only disease could derive prolong disease control with single agent ET. Further understanding the predictive markers for sensitivity to ET alone and P+ET in both endocrine sensitive and resistant settings could help guide clinical treatment sequencing decision. We performed biomarker (BM) analysis of baseline tumor tissues in both PALOMA-2 (P2) and PALOMA-3 (P3) in bone only (BO) vs non-bone (NBO) only patients. Methods: Postmenopausal women (N=666) with no prior systemic therapy for ER+/HER2-ABC were randomized 2:1 to receive PAL+LET or matching placebo (PBO)+LET in P2. In P3 women (N=521) who progressed on prior endocrine therapy were randomized 2:1 to receive PAL+ FUL vs matching PBO+FUL. All pts including those with BO disease had to consent to provide tumor tissues to participate the current study. EdgeSeq Oncology Biomarker Panel (HTG Molecular Diagnostics; Tucson, AZ) was used for mRNA profiling. Cox regression analysis was used to evaluate the association of BO disease with treatment effect as well as the association of gene expression with treatment effect in BO vs NBO pts. Results: Treatment effect in the BM population from each study was consistent with that observed in the respective ITT population. In ITT population, BO disease was reported in 151 (23%) pts of P2 with mPFS 36.2mo PAL+LET arm (n=103) vs 11.2mo LET arm (n=48), HR=0.40 (0.26-0.62) and in 124 (24%) pts of P3 with mPFS 14.3mo PAL+FUL arm (n=86) vs 9.2mo FUL arm (n=38), HR=0.64(0.38-1.06). BO disease was reported in 107 (24%) pts in P2 and 81 (27%) pts in P3 BM population. In P2, longer mPFS was seen with PAL+ LET vs PBO+LET in BO vs NBO disease (30.6 mo vs 11.2 mo; HR=0.42 (0.25-0.69) in BO pts and 22.1 mo vs 13.8 mo HR=0.67 (0.52-0.88) in NBO pts) although the interaction effect was not statistically significant. Similar results were also observed in P3 with longer mPFS in PAL+FUL vs PBO+FUL in BO vs NBO disease (16.6 mo vs 11.2 mo HR=0.79 (0.40-1.56) in BO pts and 11.1mo vs 3.5 mo HR=0.47 (0.34-0.66) in NBO pts) with insignificant interaction effect. In both studies, BO pts had higher incidence of luminal A disease (BO vs NBO: P2=62% vs 47%; P3=54% vs 40%) and lower rate of luminal B disease (P2=19% vs 33%; P3: 26% vs 33%). In both studies, baseline ESR1, Cyclin E and CDK 4 gene expression level were comparable between BO vs NBO pts. Elevated CDK4 gene expression level was associated with resistance to LET in P2 and lower Cyclin E gene expression predicts the effect of PAL in P3. Conclusion: mPFS was significantly prolonged in BO pts with the addition of PAL to ET. BO disease was more frequently associated with luminal A subtype in ABC setting. CDK4 expression level was similar to NBO disease pts but associated with resistance to single agent LET. Citation Format: Finn RS, Turner NC, Liu Y, Rugo HS, Loibl S, Diéras V, Slamon DJ, André F, Gelmon K, DeMichele A, Loi S, Zhang Z, Giorgetti C, Gauthier E, Huang Bartlett C, Cristofanilli M. Biomarker analysis of CDK 4/6 and endocrine pathways in hormone-receptor positive (HR+) advanced breast cancer (ABC) bone only disease patients: A joint analysis of PALOMA-2 and PALOMA-3 studies [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P6-18-03.

Background: Hyperactivation of the phosphatidylinositol-3-kinase (PI3K) pathway can occur due to PIK3CA mutations, present in ~40% of patients (pts) with hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2—) ABC. SOLAR-1, a Phase 3 randomized, double-blind trial (NCT02437318), investigated efficacy and safety of ALP (α-specific PI3K inhibitor) + FUL in pts with HR+, HER2— ABC. ALP+FUL met the primary endpoint by significantly extending progression-free survival (PFS) vs placebo (PBO) + FUL in the PIK3CA-mutant cohort (hazard ratio [HR] 0.65; 95% CI 0.50—0.85; p=0.00065; median 11.0 vs 5.7 months). Here we report overall survival (OS), subgroup data and safety in the PIK3CA-mutant cohort, and PFS by circulating tumor (ct)DNA PIK3CA mutation status in the total population. Methods: Enrollment was open to men/postmenopausal women with PIK3CA-mutant HR+, HER2— ABC and 1 prior line of endocrine therapy. Pts were randomized (1:1) to ALP (300mg/day) + FUL (500mg every 28 days and Cycle 1 Day 15) or PBO+FUL. OS was the key secondary endpoint. PFS was analyzed by PIK3CA mutant status in ctDNA, and in important prognostic subgroups, including line of treatment in ABC and prior cyclin-dependent kinase 4/6 inhibitor (CDK4/6i) use. Safety was analyzed in the PIK3CA-mutant cohort. Results: 341 pts in the PIK3CA-mutant cohort received ALP+FUL (n=169) or PBO+FUL (n=172). Median follow-up from randomization to data cut-off was 20.0 months. At data cut-off, 92 deaths had occurred (52% of the total 178 pts planned for final OS analysis); 40 for ALP+FUL (24%) and 52 for PBO+FUL (30%). OS results were immature at data cut-off (HR 0.73; 95% CI 0.48—1.10; p=0.06; median not estimable vs 26.9 months). There was a 45% risk reduction in PFS for pts with ctDNA PIK3CA mutations (HR 0.55; 95% CI 0.39—0.79; n=186); 20% for pts without (HR 0.80; 95% CI 0.60—1.06; n=363). PFS treatment effect for ALP+FUL vs PBO+FUL was generally consistent across subgroups of interest, with a risk reduction of 29% for pts receiving first-line (1L) treatment (HR 0.71; 95% CI 0.49—1.03; n=177), and 39% for 2L treatment (HR 0.61; 95% CI 0.42—0.89; n=161); 52% in pts with prior CDK4/6i (HR 0.48; 95% CI 0.17—1.36; n=20) and 33% in pts without (HR 0.67; 95% CI 0.51—0.87; n=321). Most frequent all-grade adverse events (AEs; ≥40% in either arm by single preferred term; ALP+FUL vs PBO+FUL) were hyperglycemia (65% vs 9%), diarrhea (54% vs 11%), nausea (46% vs 20%), and rash (40% vs 6%). Grade 3/4 AEs in ≥10% pts in either arm were hyperglycemia (fasting plasma glucose >250mg/dL; 37% for ALP+FUL vs Conclusions: ALP+FUL showed consistent clinically meaningful treatment benefit for pts with ctDNA PIK3CA mutant status, and across pt subgroups, including pts with/without prior treatment for ABC and prior CDK4/6i use. OS data were not yet mature at the data cut-off, but OS appeared numerically longer for ALP+FUL vs PBO+FUL after 52% of events. Key words: advanced breast cancer; PI3K; alpelisib; endocrine therapy Citation Format: Juric D, Ciruelos E, Rubovszky G, Campone M, Loibl S, Rugo HS, Iwata H, Conte P, Mayer IA, Kaufman B, Yamashita T, Lu Y-S, Inoue K, Takahashi M, Pápai Z, Longin A-S, Mills D, Wilke C, Sellami D, Andre F. Alpelisib + fulvestrant for advanced breast cancer: Subgroup analyses from the phase III SOLAR-1 trial [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr GS3-08.

Background: Patients with HER2-positive early breast cancer who have residual invasive disease after neoadjuvant chemotherapy plus HER2-targeted therapy have a high risk of recurrence and death. The current standard of care is continuation of the same HER2-targeted therapy in the adjuvant setting for one year. T-DM1 has shown activity and a favorable benefit-risk profile in metastatic patients with disease progression after prior chemotherapy plus HER2-targeted therapy. Thus, T-DM1 may also be active in patients with residual invasive disease after neoadjuvant HER2-targeted therapy. Methods: KATHERINE (NCT01772472/BO27938/NSABP B-50-I/GBG 77) is a phase III, open-label, global study of patients with centrally confirmed HER2-positive (IHC3+ or ISH+) primary breast cancer (T1–4, N0–3, M0) who received neoadjuvant chemotherapy plus HER2-targeted therapy, which had to include a taxane and trastuzumab, followed by surgery, with pathologically documented residual invasive disease in the breast and/or axillary lymph nodes. Within 12 weeks of surgery, patients were randomized 1:1 to T-DM1 (3.6 mg/kg IV q3w) or trastuzumab (6 mg/kg IV q3w), for 14 cycles. Randomization was stratified by clinical stage at presentation, hormone receptor status, single versus dual neoadjuvant HER2-targeted therapy, and pathological nodal status after neoadjuvant therapy. Patients received radiotherapy and/or endocrine therapy per local standards. The primary endpoint is invasive disease-free survival (IDFS). A single interim analysis (IA) was planned after approximately 67% of the IDFS events required for the primary analysis had occurred, with an efficacy stopping boundary of HR?0.732 or p Results:After review of the pre-specified IA, the IDMC recommended full analysis and disclosure of the results. With 256 IDFS events reported, administration of T-DM1 significantly improved IDFS compared with trastuzumab (unstratified HR=0.50; 95% CI: 0.39 to 0.64; p Conclusions: Adjuvant T-DM1 substantially improved IDFS in patients with HER2-positive early breast cancer with residual disease after completion of neoadjuvant therapy. Citation Format: Geyer, Jr. CE, Huang C-S, Mano MS, Loibl S, Mamounas EP, Untch M, Wolmark N, Rastogi P, Fischer HH, Redondo A, Jackisch C, Jacot W, Conlin AK, Schneeweiss A, Wapnir IL, Fasching PA, DiGiovanna MP, Wuelfing P, Arce-Salinas C, Crown JP, Shao Z, Rota Caremoli E, Wu H, Lam LH, Tesarowski D, Smitt M, Douthwaite H, Singel SM, von Minckwitz G. Phase III study of trastuzumab emtansine (T-DM1) vs trastuzumab as adjuvant therapy in patients with HER2-positive early breast cancer with residual invasive disease after neoadjuvant chemotherapy and HER2-targeted therapy including trastuzumab: Primary results from KATHERINE [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr GS1-10.

Background: Currently, patients with breast cancer (BC) with hormone receptor (HR) immunohistochemical expression between 1-9% are eligible to receive endocrine therapy. However, recent data suggest that these tumors express a basal-like molecular phenotype associated with triple negative BC (TNBC) rather than luminal phenotype associated with HR positive BC. Here, we aimed to determine the differences between strong HR positive, low HR positive and negative HR BC, in regard to responsiveness to neoadjuvant chemotherapy (NACT) and disease free survival (DFS) in large cohorts from GBG clinical trials. Methods: In this retrospective analysis of data from women with BC treated in the neoadjuvant GeparQuinto (n=2572), GeparSixto (n=588) and GeparSepto (n=1206) clinical trials, we compared patients with three HR phenotypes: low positive (ER and/or PR= 1-9%), strong positive (ER or PR= 10-100%), and negative (ER and PR= Results: Patients median age was 49 years, the majority had clinical tumor stage 2 (54.1%), negative nodal status (54.7%), and Her2 negative tumors (72.4%). 85.1% of women had BC classified as no special histological type. The pCR rate across the studies was 26.2%. 145 (3.4%) patients had low HR positive, 2417 (57.3%) strong HR positive and 1658 (39.3%) HR negative tumors. After NACT, 16.3% of patients with strong HR positive BC achieved a pCR, while among those with HR negative and low HR positive tumors, pCR rates were 40.2% and 37.9%, respectively (p Conclusions: Similarly to patients with negative HR tumors, patients with low HR positive tumors have a better responsiveness to NACT and worse survival rates, compared to patients with strongly HR positive BC. We suggest that studies on treatment options for basal-like/TNBC, should also consider including patients with low HR positive tumors. Citation Format: Villegas SL, Lederer B, Untch M, Holms F, Ulmer H-U, Diebold K, Fasching PA, Weber K, Schmitt WD, Tesch H, Rezai M, Marmé F, Sinn B, Hackmann J, Schneeweiss A, Tannapfel A, Nekljudova V, Denkert C, Loibl S. Similarities between low hormone receptor positive and hormone receptor negative breast cancer: An analysis of 4366 patients from multicenter clinical trials [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-08-10.

Introduction Breast cancer diagnosed in young women who are 40 years (yrs) or younger is a relatively rare disease. However, it represents the most common cause of cancer-related deaths in this age-group. Furthermore, young age at diagnosis is associated with an increased risk of recurrence and worse survival. To date, general concepts concerning oncological cancer management should be driven by clinicopathological tumor characteristics and should adhere to standardized protocols for patients in general, but little is known about the oncological cancer treatment and outcome of this very young women in today's clinical practice. Patients and Methods The breast cancer in pregnancy registry study (BCP/GBG29/BIG 03-02) is a multicenter, international, observational study. BCP was established to investigate the oncological management and outcome of breast cancer in pregnancy. Since 2014 non-pregnant patients who are 40 yrs or younger are eligible if diagnosed with histological confirmed invasive breast cancer, independent of the type of treatment as control cohort. All patients received oncological treatment according to local standards. In this study the following endpoints will be analyzed descriptively for the young non-pregnant women cohort: breast cancer staging at diagnosis, biological characteristics of breast cancer at diagnosis, diagnostic procedures, treatment modalities, toxicity, pathological complete response after neoadjuvant chemotherapy, disease-free survival and overall survival. Results From February 2014 until June 2018, 969 non-pregnant patients ≤40 yrs have been registered. The median age at diagnosis was 35 yrs (range 19-40). Overall, 90.1% of patients had a stage T1-2 at diagnosis and 67.1% of patients had negative lymph nodes. 86.7% of tumors were invasive ductal carcinomas and 4.1% lobular carcinomas. Grading (G) 3 was reported in 55.5%. 26.6% of tumors were luminal A-like (ER- and/or PgR-positive, HER2-negative, G1-2), 40.0% luminal B-like (ER- and/or PgR-positive, HER2-negative, G3 or ER- and/or PgR-positive, HER2-positive, any G), 7.7% HER2 positive non-luminal-like, and 25.7% triple negative breast cancers. 3.8% of young non-pregnant patients had metastatic disease at primary diagnosis. Conclusion This registry comprises a large cohort of young non-pregnant patients with breast cancer diagnosed at the age of 40 yrs or younger and provides important data about a modern breast cancer treatment as well as oncological outcome in this setting of young women. Further results including oncological management, toxicity, and survival will be presented at the meeting. Citation Format: Seiler S, Schmatloch S, Reinisch M, Neunhöffer T, Schmidt M, Bechtner C, Marmé F, Wagner M, Möbus V, Reimer T, Kleine-Tebbe A, Sinn B, Stickeler E, Untch M, Janni W, Seither F, Loibl S. Cancer management and outcome of very young non-pregnant patients with breast cancer diagnosed at 40 years or younger– GBG 29 [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P1-17-07.

Introduction: Recent studies showed the high and independent impact of age (65 years) for NACT due to poor prognosis or higher toxicity. The aim of this analysis is to help selecting appropriately elderly women who would benefit from NACT. Secondly, survival parameters will be investigated in several clinical and histological subgroups. Methods: From 1998 to 2010, eight prospectively randomized German Breast Group (GBG) trials of anthracycline- and taxane-based NACT were performed and analyzed in this study. Results: Compared to the overall average, women older than 65 years had significant larger tumors and more overall lymph node involvement. Also, compared to patients younger than 51 years, they had more lobular invasive tumors. Histologically, they had more G2 tumors, more estrogen-receptor positive tumors. PCR (ypT0 ypN0) was strongly associated with age: >65y: 11.7%; 51-65y: 14.1%; 40-50y: 17.3%; 65years is a predictor of significant (p Discussion: This study underlines the unfavorable impact of higher age on pCR, but it shows nevertheless a realistic chance for pCR if NACT is applied - especially for HER2+ patients. Furthermore, elderly patients in this analysis with non-TNBC have a good prognosis (comparable to younger patients) regarding OS, even if they do not have pCR. Citation Format: von Waldenfels G, Loibl S, Furlanetto J, Anna M, Lederer B, Denkert C, Hanusch C, Huober J, Jackisch C, Kümmel S, von Minckwitz G, Schneeweiss A, Untch M, Rhiem K, Fasching PA, Blohmer JU. Outcome after neoadjuvant chemotherapy in elderly breast cancer patients – a pooled analysis of individual patient data from eight prospectively randomized controlled trials [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P6-15-03.

Background Over 90% of male breast cancer (BC) patients (pts) have hormone receptor (HR) positive disease. Until today tamoxifen is considered to be the standard of care in male BC pts. Due to the low incidence of male BC, there is a lack of data regarding efficacy and safety. Therapeutic strategies are extrapolated from the standard of care of female BC. However, no prospectively randomized study in male BC pts has been conducted so far. The Male-GBG54 study is the first prospective, randomized, multicenter trial evaluating the efficacy and safety of different endocrine treatment options in male BC patients. Patients and Methods In the phase II Male-GBG54 trial (NCT01638247), pts were randomized to receive either tamoxifen 20 mg/day per os (p.o.) or tamoxifen 20mg/day p.o. + GnRHa subcutaneous (s.c.) q3m or exemestane 25 mg/day p.o. + GnRHa s.c. for 6 months as (neo)adjuvant or metastatic therapy. Further treatment was conducted as per local guidelines. Primary objective was the suppression of oestradiol in the three treatment arms after 3 months of therapy. Secondary objectives comprised oestradiol suppression after six months, compliance and safety of the three therapies, the level of different steroidal hormones (testosterone, dihydrotestosterone, SHBG, FSH, LH) and osteocalcin in the three arms. Quality of Life was assessed using the Aging Male Symptom Score, International Index of Erectile function and International Prostate Symptom Score. Tissue and blood was collected for translational research. Male BC pts with a Karnofsky Index ≥60%, normal blood lipids, and no history or evidence of prostate cancer were eligible. 14 pts per group were needed for the F-test to have 80% power to detect a difference in mean oestradiol decrease between the three therapeutic groups at the 5% significance level. The final sample size was calculated as 48 patients, as a non-parametric test (Kruskal-Wallis) was chosen in case the oestradiol levels are not normally distributed within the study population. Results Between October 2012 and May 2017, 55 pts were randomized within 24 centers in Germany. 52 pts were included in the adjuvant and 2 pts in the metastatic setting of whom 48 pts were fully evaluable and comprised the analysis set. The median age was 62 years (range 37-83 years). The baseline characteristics were well balanced between the 3 treatment groups. Karnofsky Index ranged from 60%-100%, 36.4% had received prior chemotherapy and 12.7% had HER2-positive BC. The majority had a pT2 (52%), pN0 (58.0%) BC. 3 serious adverse events were reported, none was related to the study treatment. Conclusion This is the first prospective randomized trial worldwide evaluating the impact of three different endocrine treatments in male breast cancer. The therapy was well tolerated without safety signals. At the meeting, final results of the primary and secondary endpoints will be present. Citation Format: Reinisch M, Seiler S, Hauzenberger T, Schmatloch S, Strittmatter HJ, Zahm DM, Thode C, Jackisch C, Furlanetto J, Strik D, Stickeler E, Marmé F, Janni W, Schmidt M, Kamischke A, Rudlowski C, Nekljudova V, von Minckwitz G, Loibl S. Male-GBG54: A prospective, randomised multi-centre phase II study evaluating endocrine treatment with either tamoxifen +/- gonadotropin releasing hormone analogue (GnRHa) or an aromatase inhibitor + GnRHa in male breast cancer patients [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr PD7-10.

Background A new subcutaneous (s.c.) formulation of trastuzumab became available in 2013 based on equivalent efficacy, pharmacokinetic (PK) profile and safety with the standard intravenous (i.v.) administration, where the s.c. trastuzumab was administered only into the thigh. As an s.c. injection into the abdominal wall (abdw) might be more convenient for patients (pts) and health care professionals, the PK profile of s.c. trastuzumab injected into the thigh vs the abdw in pts with HER2+ early BC needs to be evaluated. Methods GAIN-2 study compared two intense dose-dense (idd) anthracycline/taxane containing regimens. After completion of the anthracycline and i.v. trastuzumab given concurrently with taxanes, HER2+ BC pts were randomized in a 1:1 ratio to continue adjuvant s.c. trastuzumab 600mg fixed dose injected every 3 weeks either into the thigh or the abdw. Randomization was stratified according to CT arm [(iddEnPC) vs tailored dd CT (dtEC-dtD)] and age (≤50 vs >50). Pts in the EnPC arm received 14 and in the dtEC-dtD arm 15 cycles of s.c. trastuzumab. For the PK profile of s.c. trastuzumab serum samples collected before cycle 7, on days 2, 4, 8, 15 and 21 of cycle 7 are evaluated. With a total sample size of 30 (15 per group), the simulated 90% two-sided CI for the area under the plasma concentration (AUC0-last) will be (0.79-1.27) and for the peak drug concentration (Cmax) will be (0.77-1.30). Allowing for a dropout rate of 15%, 18 pts per group will be included in the PK analysis. The primary objective was to assess the PK profile of s.c. trastuzumab injected into the thigh vs the abdw. The secondary objectives included safety and tolerability. Results The per-protocol (pp) set consists of 30 pts (17 in the thigh group and 13 in the abdw group). Baseline characteristics were well balanced between the groups. The log-transformed Geometric Least Square Means (GLSM) for Cmax were 11.77 and 11.52 in the thigh and the abdw group, respectively. The geo-mean ratio (on the original scale) for Cmax was 1.29 (90% CI 1.05-1.58). The log-transformed GLSM for AUC0-last were 14.54 and 14.28 in the thigh and the abdw group, respectively. The geo-mean ratio for AUC0-last was 1.29 (90% CI 1.02-1.63). Overall 29 pts (96.7%) reported any grade and 5 pts (16.7%) high grade adverse events (AEs). The incidence of any grade AEs was similar between the two groups. The most common AEs were anemia (70.6% for the thigh vs 61.5% for the abdw group, p=0.705), leukopenia (80.0% for both groups, p=1.000) and fatigue (47.1% for the thigh vs 76.9% for the abdw group, p=0.141). 6 serious AEs were reported (2 in the thigh vs 4 in the abdw group). The final PK results of s.c. trastuzumab will be presented at the meeting. Conclusions Bioavailability of s.c. trastuzumab as reflected by peak and total exposure measured in cycle 7 was approx. 30% higher if administered into the thigh than into the abdw in pts with HER2+ primary BC treated after dose-dense CT plus i.v. trastuzumab. However, no increased toxicity was observed. Study limitations were that no cross-over design was used and number of pts satisfying criteria for pp-set were different in the arms. Citation Format: Möbus V, Mahlberg R, Janni W, Tomé O, Marmé F, Forstbauer H, Reimer T, von der Assen A, Reinisch M, Lorenz R, Schmatloch S, Schmidt M, Sinn B, Klutinus N, Stickeler E, Untch M, Seiler S, Burchardi N, von Minckwitz G, Loibl S. Pharmacokinetic results of a subcutaneous injection of trastuzumab into the thigh versus into the abdominal wall in patients with HER2-positive primary breast cancer (BC) treated within the neo-/adjuvant GAIN-2 study [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P5-20-09.

This abstract was withdrawn by the authors.

Background: The incidence of brain metastases (BM) in breast cancer patients is rising and has become a major clinical challenge. So far, the incidence of BM after modern neoadjuvant treatment is not clear. Materials and Methods: In Geparquinto, patients with untreated HER2-positive breast cancer (n=615) received either lapatinib or trastuzumab, patients with HER2 negative breast cancer (n=1925) received bevacizumab in addition to an anthracycline and taxane-containing regimen and those not responding paclitaxel and everolimus (n=32). In Geparsixto, patients with HER2-positive tumors (n=273) received trastuzumab and lapatinib and patients with triple-negative tumors (n=315) received bevacizumab in addition to chemotherapy. We analyzed clinical factors associated with the occurrence of BM as first site of metastatic relapse after neoadjuvant treatment in both trials (n=3160). Results: After a median follow-up of 61 months, 108 (3%) of a total of 3160 patients developed BM as first site of recurrence and 411 (13%) patients had distant metastases outside the brain. Brain metastases as first site of recurrence occurred later than other metastases (3--year-relapse free-rate 96.7% for patients who developed BM and 89.5% for patients who developed metastases outside the brain). Regarding subtypes of the primary tumor, 1% of luminal A (11/954), 2% of luminal B (7/381), 4% of HER2 positive (34/809) and 6% of triple-negative patients (56/1008) developed BM as first site of recurrence. In multivariate analysis, risk factors for the development of BM were larger tumor size (cT3-4; HR 1.9, 95%-CI 1.3-2.8, p=0.0022), node positive disease (HR 2.8, 95% CI 1.8-4.4, p Conclusion: Especially patients with HER2-positive and triple negative tumors are at risk of developing BM despite active systemic treatment. A better understanding of the underlying mechanisms is required in order to develop potential preventive strategies. Citation Format: Witzel ID, Laakmann E, Fasching PA, Rezai M, Schem C, Solbach C, Tesch H, Klare P, Schneeweiss A, Zahm D, Blohmer J, Ingold-Heppner B, Huober J, Hanusch C, Jackisch C, Reinisch M, Untch M, von Minckwitz G, Müller V, Loibl S. Development of brain metastases in breast cancer patients treated in the neoadjuvant trials Geparquinto and Geparsixto [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P1-17-01.

Background: RNA-Seq from total RNA in FFPE tissue can be more challenging due to limited capture of partially degraded RNA. Exome-capture based RNA-Seq may circumvent such problems and allow reproducible complete molecular characterization of low-quality RNA from small clinical samples. Methods: HER2 negative patients within the GeparQuinto trial were treated with neoadjuvant anthracycline-taxane-based chemotherapy +/- bevacizumab. Patients with bevacizumab therapy had a significantly higher pCR rate, especially within the triple negative subgroup. We performed exome-capture RNA-Seq on 5µm FFPE sections from pre-therapeutic cores of 400 HER2 negative samples from this trial. In a prospectively planned, blinded study we correlated molecular subtypes and metagenes for proliferation, stroma, MHC2, and VEGFA with clinical and histopathological data. Molecular subtypes were defined using the AIMS methods. Metagenes were calculated as mean values corresponding to previously described gene clusters after platform transfer (Rody et al. 2011 PMID 21978456, Hu et al. 2009 PMID 19291283) and then z-transformed. Results: 296 samples with RNA-Seq data were classified as either of high (n=226) or of limited quality (n=70). For 22 samples RNA yield was insufficient and 82 did not pass initial QC. 121 (41%), 63 (21%), 34 (11.5%), 46 (15.5%), and 32 (11%) samples were defined as basal-like, HER2-enriched, luminal A, luminal B, and normal-like, respectively. Subtyping was robust with regard to gene filtering, normalization, and sample quality. ER and PR status from local IHC strongly correlated with gene expression (overall correctness 84% and 80% for ER, and 85% and 74% for PR, in samples with high and limited quality, respectively) and luminal subtypes (95% ER positive). Proliferation metagene correlated with histological grade (median -0.73, -0.39, and 0.53 in G1, G2, and G3, respectively; P Conclusions: Exome-capture RNA-Seq allows robust genomic characterization of clinical samples with limited FFPE material from core biopsies, and molecular subtypes and immune metagenes are predictive for pCR. The VEGFA metagene is a specific predictor for response to neoadjuvant bevacizumab treatment. Citation Format: Karn T, Meissner T, Weber K, Sinn B, Denkert C, Budczies J, Nekljudova V, Fasching PA, Holtrich U, Schem C, Solbach C, Hartmann A, Röcken C, Untch M, Young BM, Willis S, Leyland-Jones B, von Minckwitz G, Loibl S. Blinded molecular subtyping analysis from RNA-Seq of FFPE samples in the GeparQuinto trial reveals predictive value of VEGFA metagene for bevacizumab treatment [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P2-09-02.

Background: Interactions between cancer cells and the host immune system influence tumor biology, response to therapy and patient survival and their modulation offers promising new approaches for cancer therapy. The downregulation or loss of HLA class I expression in breast cancer cells might be an effective mechanism to evade the recognition by the immune system facilitating malignant behavior. Aim: To evaluate the association of tumor-infiltrating lymphocytes (TILs) with HLA class I expression and its theranostic value for therapy response and survival after neoadjuvant chemotherapy. Methods: HLA class I expression was evaluated by immunohistochemistry in a cohort of 732 pre-therapeutic core biopsies from breast cancer patients treated within the neoadjuvant GeparTrio trial. Patients received anthracycline- and taxane-based neoadjuvant therapy and adjuvant endocrine treatment if hormone receptor-positive (HR+). A publicly available microarray dataset of pre-therapeutic core biopsies from 508 breast cancer patients that received neoadjuvant chemotherapy and endocrine treatment if HR+ was used for validation of the results. The association of HLA class I expression with predefined genomic signatures for immune cell populations was evaluated in publicly available data from the cancer genome atlas. Results: HLA class I expression was associated with TILs (p < 0.001) and was predictive of better response to neoadjuvant chemotherapy in the subgroup of patients with HR+/HER2- breast cancer (14 % in tumors with high HLA vs. 7 % in tumors with low HLA, p = 0.029). Interestingly, high HLA was also predictive for shorter progression-free survival in univariate analysis (HR 1.590, 95 % CI 1.062—2.380; p = 0.024) and after adjustment to clinical and pathological parameters (HR 1.701, 95 % CI 1.105—2.618; p = 0.016). The results could be validated in the independent microarray-based dataset (HR 1.521, 95% CI 1.088 – 2.129; p = 0.0142). HLA class I was not associated with therapy response or survival in hormone receptor-negative breast cancer. HLA class I was associated with a predefined signature for T-cells and cytotoxic T- cells in the cancer genome atlas dataset (rho = 0.546). Conclusion: HLA class I expression is associated with better response but shorter progression-free survival in HR+/HER2- breast cancer following neoadjuvant chemotherapy. The underlying mechanisms warrant further investigation. Citation Format: Sinn BV, Weber K, Denkert C, Fasching PA, Schmitt WD, Thomas K, Ingold-Heppner B, van Mackelenbergh M, Symmans WF, Marmé F, Taube E, Müller V, Kunze CA, Schem C, Pfitzner BM, Stickeler E, von Minckwitz G, Loibl S. HLA class I expression is associated with tumor-infiltrating lymphocytes and response and survival after neoadjuvant chemotherapy in hormone receptor-positive, HER2-negative breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P1-07-01.

Background: The GeparNuevo trial is a randomized, double-blind, multi-center phase II trial of neoadjuvant therapy in patients with early-stage triple negative breast cancer (TNBC) investigating the role of durvalumab, an anti-PD-L1 antibody, which blocks PD-L1 binding to PD1 and CD80, in addition to standard anthracycline/taxane based chemotherapy (Loibl S et al. ASCO 2018). Methods: In order to determine possible predictive and / or prognostic biomarkers, blood samples were taken before and during the different treatment phases (3 or 4 time points) and evaluated by multicolor flow cytometry by monitoring the absolute cell counts of T cells, B cells and NK cells as well as the frequency, composition and functionality of different immune cell populations using a panel of 35 distinct antibodies. Results: Overall 174 patients were randomized into the GeparNuevo study. 117 patients participated in the window phase of this study and 49 patients provided evaluable material for flow cytometric analyses for material at the above specified time points. Evaluation of the absolute cell count in the whole blood prior and after therapy highlighted a mixed behavior of the total leukocytes. Overall, there was a statistically significant reduction in the lymphocyte count, particularly during the last phase of the treatment (ECdd +/- durvalumab). Further dissection into the different immune populations highlighted an almost complete loss of B cells, which in some patients was also accompanied by a reduction of NK cells, mainly of the CD16+ subset. The loss of CD4+ and CD8+ T cells was less pronounced resulting overall in an enhancement of their percentages within the total lymphocytes. In addition, the different populations have also been evaluated for the expression of PD-L1 activation and exhaustion markers. A pre-specified analysis clearly demonstrated a specific effect of durvalumab during the window phase with mean decreases of 21.7% and 15.0 % in PDL1+ lymphocytes in the CD4+ and CD8+ subgroups, respectively (P Conclusion: Using this approach we hope to identify biomarkers, which will allow a better selection of TNBC patients undergoing specific immunotherapies. Final data will be presented at the meeting. The trial and this translational research project were funded by AstraZeneca and Celgene, Germany. Citation Format: Massa C, Schneeweiss A, Karn T, Hanusch CA, Blohmer J-U, Fasching PA, Jackisch C, van Mackelenbergh M, Marmé F, Müller V, Schem C, Stickeler E, Huober J, Weber KE, Untch M, Denkert C, Loibl S, Mueller A, Biehl K, Seliger B. Immunomonitoring of triple negative breast cancer patients undergoing neoadjuvant therapy with durvalumab - Results from the prospectively randomized GeparNuevo trial [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P4-06-01.

Background: TNBC is associated with higher percentages of pathological complete response (pCR) to neoadjuvant chemotherapy (NAC), and women with a pCR have a favorable prognosis. However, Liedtke (2008) and Loibl (2017) found that women with residual disease have a substantially higher risk of recurrence than women with other subtypes of breast cancer. Additionally, Adams (2017) and Schmid (2017) found that therapeutic blockade of PD-L1 binding by atezolizumab has resulted in relevant anti-tumor efficacy. Methods: Design This is a phase III, double blind, placebo-control trial evaluating neoadjuvant atezolizumab with NAC followed by adjuvant atezolizumab in TNBC. Pts are stratified by region (North America; Europe), tumor size (1.1-3.0cm; >3.0cm), AC/EC schedule (q2w; q3w), and nodal status (positive; negative), then randomized 1:1 to receive atezolizumab/placebo 1200 mg IV every 3 wks concurrently with both sequential regimens of weekly paclitaxel 80 mg/m2 IV for 12 doses with every 3-wk carboplatin AUC of 5 IV for 4 doses followed by AC/EC every 2-3 wks (per investigator discretion) for 4 cycles. Following surgery, pts resume atezolizumab/placebo 1200 mg IV every 3 wks as adjuvant therapy for 6 months. Radiotherapy based on local standards is co-administered with atezolizumab/placebo. Eligibility criteria Centrally-confirmed ER-neg, PR-neg, HER2-neg invasive breast cancer by ASCO/CAP guidelines. Primary tumor must be stage T2 or T3 if cN0 or cN1 with negative biopsy or T1c, T2, or T3 if cN1 with positive biopsy or cN2 or cN3. LVEF >55% and no significant cardiac history. Statistical methods Co-primary endpoints are event-free survival (EFS) and pCR breast/nodes. Secondary endpoints include pCR breast, overall survival, distant disease-free survival, safety and toxicity. Trial is an academic collaboration between NSABP and GBG with support from Genentech/Roche. NCT03281954 Support: Genentech/Roche Citation Format: Geyer, Jr. CE, Loibl S, Rastogi P, Seiler S, Costantino JP, Nekljudova VN, Cortazar P, Lucas PC, Denkert C, Mamounas EP, Jackisch C, Wolmark N. A randomized double-blind phase III clinical trial of neoadjuvant chemotherapy (NAC) with atezolizumab or placebo in patients (pts) with triple negative breast cancer (TNBC) followed by adjuvant atezolizumab or placebo: NSABP B-59/GBG 96-GeparDouze [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr OT3-05-01.

Background: Particularly among patients converting from cN+ to ycN0 status through neoadjuvant therapy (NAT) the optimal method and extent of axillary staging is unclear. The aim of this analysis was to develop a nomogram predicting the probability of positive axillary status (ypN+) after PST among these patients based on clinical and pathological parameters. Methods:Patients converting from cN+ to ycN0 due to PST included in a prospective study (SENTINA, Arm C) were included. Univariate and multivariate analyses were carried out to evaluate the association between 14 clinical/pathological parameters and pathological axillary status (ypN0 vs ypN+) using logistic regression models. Model accuracy, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were assessed applying leave-one-out cross-validation (LOOCV) and ROC analyses. Different cut-points were evaluated. Calculations were performed using the SAS Software (Version 9.4, SAS Institute Inc., Cary, NC, USA.). Results: Arm C contained 553 patients, 369 patients were evaluable with respect to the above parameters. Univariate analyses revealed a significant association between pathological axillary status and ER status (odds ratio (OR) 4.05, 95% confidence interval (95%CI) 2.81-5.83), PR status (OR 3.07, 95%CI 2.16-4.36), multifocality (OR 2.37, 95%CI 1.57-3.58), lymphovascular invasion (OR 8.61, 95%CI 5.12-14.46), detection of a SLN after NAT (OR .56, 95%CI .36-.87), detection method (IHC vs routine: OR .46, 95%CI .27-.78; IHC vs serial HE: OR .72, 95%CI .49-1.07; serial hematoxylin eosin (HE) vs routine: OR .639, 95%CI .39-1.04), clinical tumor size (OR 1.051, 95%CI 1.03-1.07) and pCR-status in the breast (ypT0 and ypTis vs others, OR .11, 95%CI .08-.17). A multivariate model was fitted including significant clinical parameters. Stepwise backward variable selection was carried out resulting in a model including ER status (OR 3.81, 95%CI 2.25-6.44), multifocality (OR 2.22, 95%CI 1.26-3.92), LVI (OR 9.16, 95%CI 4.68-17.90), detection of a SLN after NAT (OR .50, 95%CI .26-.95) and clinical tumor size (OR 1.03, 95%CI 1.01-1.06). In LOOCV, this model demonstrated an accuracy of 73% (sensitivity 73%, specificity 72%, PPV 75%, NPV 70%) using .5 as cut-off. Based on the performed ROC analysis an area under the curve (AUC) of 0.81 was calculated. Conclusion: A model using ER status, multifocality, LVI, detection of a SLN after NAT and clinical tumor size was built to predict pathological axillary status (ypN+) with a high accuracy. If successfully validated based upon an independent dataset, this nomogram could allow advising patients for / against axillary surgery in case of clinical axillary conversion after NAT. Citation Format: Liedtke C, Kolberg H-C, Kerschke L, Goerlich D, Bauerfeind I, Fehm T, Fleige B, Hauschild M, Helms G, Lebeau A, Schmatloch S, Schrenk P, Schwentner L, Staebler A, von Minckwitz G, Loibl S, Untch M, Kuehn T. Development and validation of a nomogram predicting pathological axillary status (ypN0 vs. ypN+) in a subgroup of patients converting from cN+ to ycN0 through neoadjuvant therapy (NAT) – A transSENTINA substudy [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P3-13-06.

Background Reduced quality of life during chemotherapy is often due to fatigue and dyspnea caused by chemotherapy-induced anemia. In breast cancer patients the incidence is estimated to be above 50% and rising during the course of treatment resulting as well in therapy delays. Despite red blood cell transfusion the administration of erythrocyte stimulating factors (ESF) serves as a treatment option. In comparison with conventional chemotherapy intense dose dense regimens have proven to be beneficial in high-risk breast cancer patients, but higher incidences of anemia have been reported. In the GAIN trial two dose dense regimens were evaluated and patients received either Darbepoetin alfa or Epoetin beta. The aim of this subanalysis was to analyse the efficacy and safety of the application of two different ESF during adjuvant chemotherapy for primary node positive breast cancer. Methods Patients were randomly assigned to receive three courses each of epirubicin (E), paclitaxel (T), cyclophosphamide (C) all given at 2-week intervals i.v. (idd ETC-regimen) or ddEC followed by paclitaxel weekly (Tw) plus capecitabine (X)(EC-TX-regimen).All patients received either primary prophylaxis with Epoetin beta (Epo) (450IE/kg weekly) or Darbepoetin alfa (D) (4,5μg/kg biweekly).Allocation happened alternately by date of randomization. Patient outcome (rate of anemia and thromboembolic events, disease free survival (DFS), overall survival (OS)), overall and by regimen were compared according to ESF type applied and in subgroups defined by age. Results 2994 patients were randomized to receive one of the dose dense chemotherapies and of these 1482 patients were given Darbepoetin alfa and 1512 received Epoetin beta. In the trial 84.7% of patients suffered from anemia in the Darbepoetin as well as in the Epoetin group and grade 3/4 anemia was observed in 3.6% vs 3.1% of patients, respectively. In the ETC arm anemia rates, especially grade 3/4 were slightly higher, but there was no significant difference within the treatment arms according to ESF applied (anemia any grade: D 86.1% vs. Epo 87.2%; EC-TX: D 83.2% vs. Epo 82.3%). In the ETC arm anemia was most frequently observed in patients aged 60+ years, but there was no significant difference between the ESF (D 90.5% vs. Epo 89.8%). No significant differences in the incidence of anemia by ESF treatment were observed in various age groups of the EC-TX arm. Thromboembolic events occurred in 9.1% in the Darbepoetin group and in 10.1% of patients treated with Epoetin (p=0.355). Interestingly there were more thromboembolic events in the EC-TX arm compared to the ETC arm (p OS and DFS analyses showed no difference between ESF treatment overall as well as stratified by chemotherapy regimen. Conclusion High risk breast cancer patients treated with two different dose dense chemotherapy schedules have comparable incidences of anemia, thromboembolic events and a similar long term outcome if they receive a preventive treatment with either Darbepoetin alfa or Epoetin beta. The trial is financially supported by Amgen and Roche. Citation Format: van Mackelenbergh M, Loibl S, Jackisch C, Lück H-J, Schneeweiss A, Tesch H, Harbeck N, Schmatloch S, Fehm T, Huober J, Müller V, Bauerfeind I, Untch M, von Minckwitz G, Nekljudova V, Möbus V. Efficacy and safety of darbepoetin alfa or epoetin beta in 2994 high risk early breast cancer patients participating in the German adjuvant intergroup node-positive study (GAIN) [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P2-11-04.

This abstract was withdrawn by the authors.

Background Our recent randomized, multicenter phase III GeparSepto study (Untch M et al. Lancet Oncol 2016) found that substituting nab-paclitaxel for standard solvent-based paclitaxel significantly improved the pathologic complete response (pCR) rate in patients receiving a sequential regimen of taxane, epirubicin and cyclophosphamide as neoadjuvant treatment for high-risk primary breast cancer. Patients with HER2-positive tumors (32.8%; n=396) also received a combination of pertuzumab and trastuzumab: the present analysis focuses on efficacy and safety data from these HER2+ patients treated with the dual-blockade. Methods Patients with histologically confirmed early breast cancer (n = 1206) received either weekly paclitaxel 80mg/m2 or weekly nab-paclitaxel 150/125mg/m2, according to randomization), followed by four cycles of epirubicin 90 mg/m2 plus cyclophosphamide 600 mg/m2 q3w, with concurrent trastuzumab 6 mg/kg (loading (LD) dose 8 mg/kg) and pertuzumab 420 mg (LD 840 mg) q3w for those with HER2-positive tumors. The primary endpoint was pathologic complete response (pCR), defined as ypT0 ypN0. Results The GeparSEPTO trial included 396/1206 (32.8%) HER2+ primary breast cancer patients. 27.0% in the HER2-positive and 34.1% in the HER2-negative group had HR-negative disease. Baseline characteristics were otherwise comparable between HER2+ and HER2- patients. Higher rates of pCR were seen in HER2+, compared to HER2- tumors (57.8% vs 22.0%). The highest overall pCR rate was observed in the HER2+/HR- cohort with 71.0%; 66.7% with Pac and 74.6% with nab-Pac. In HER2+/HR+ pCR rate was 52.9% ; 49.4% with Pac and 56.4% with nab-Pac. Using the definition ypT0/is ypN0 for pCR; pCR rates were generally higher especially in the HER2+ cohort (66.2% (ypT0/is ypN0) vs 57.8% (ypT0 ypN0)) compared to 25.2% (ypT0/is ypN0) vs 22% (ypT0 ypN0)) in patients with HER2-negative tumors. The HER2+ patients experienced a significantly higher incidence of grade 3-4 adverse events 85.4% vs 78.0% in the HER2-cohort, p=0.003); grade 3-4 hematologic AEs 74.0% (HER2+) vs 69.5% (HER2-); p=0.120 with grade 3-4 anaemia 2.5% vs 0.9%; p=0.034); any grade thrombopenia 28.5% vs 21.8%; p=0.012) and febrile neutropenia 6.3 vs 3.3%; p=0.023. Any grade 3-4 non-haematological toxicities occurred in 38.4% vs 30.1%; p=0.005), with grade 3-4 diarrhea occurring in 7.6% vs 0.9%; p Conclusion This is the largest cohort of patients with HER2-positive early breast cancer receiving a dual HER2-targeted neoadjuvant therapy of pertuzumab and trastuzumab, together with nab-paclitaxel or paclitaxel followed by epirubicin and cyclophosphamide. HER2+ patients experienced more noteworthy toxicity. The pCR rate were higher in the HER2+ cohort receiving the dual blockade and was highest in patients with in HER+/HR- particularly if nab-paclitaxel was substituted for paclitaxel. The trial is financially supported by Celgene and Roche. Citation Format: Loibl S, Jackisch J, Schneeweiss A, Schmatloch S, Aktas B, Denkert C, Schem C, Wiebringhaus H, Kuemmel S, Luebbe K, Warm M, Just M, Hanusch C, Hackmann J, Blohmer J-U, Clemens M, Engels K, Nekljudova V, von Minckwitz G, Untch M. Dual HER2-blockade with pertuzumab and trastuzumab in HER2-positive early breast cancer: A subanalysis of data from the randomized phase III GeparSepto trial [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P4-21-06.

Background: Tumor-infiltrating lymphocytes (TILs) have been shown to be predictive for response to neoadjuvant therapy, in particular in triple-negative and HER2 positive breast cancer, suggesting that subtypes of breast cancer are immunogenic. The role of TILs in luminal breast cancer as well as the impact on prognosis in the different subtypes is less clear. In this study we evaluated TILs in a total of 3771 breast carcinomas from 6 prospective neoadjuvant clinical trials and evaluated their relevance for pCR, DFS and OS in different molecular subtypes. Methods: A total of 3771 tumors from the clinical studies GeparDuo, GeparTrio, GeparQuattro, GeparQuinto, GeparSixto, GeparSepto were evaluated for stromal TILs by standardized methodology. Data on pCR were available for all tumors, DFS and OS was available for 2560 tumors. Logistic regressions, Cox regressions and Kaplan-Meier analyses were performed. In addition, a combined analysis of pCR, survival and TILs in different subtypes was performed. Results: In the complete cohort of 3771 tumors, increased TILs (>=60%) were observed in 19% of tumors, these tumors with >=60% TILs had a pCR rate of 44% (p=60%) were observed in 30% of TNBC (n=906), in 19% of HER2+ tumors (n=1379) and in 13% of HR+/HER2- tumors (n=1366). In all three subtypes, increased TILs were significantly associated with increased pCR rates (p=60%) were associated with worse survival in Kaplan-Meier analysis in luminal tumors (DFS: p=0.04, OS: p Conclusion: Our results suggest that tumor-infiltrating lymphocytes are a strong predictive marker for response to neoadjuvant chemotherapy in all molecular subtypes, and this predictive effect is translated into a survival benefit in HER2+ BC and TNBC. In contrast, a survival benefit is not observed in luminal BC, suggesting a different biology of the immunological infiltrate in this subtype. Citation Format: Denkert C, von Minckwitz G, Darb-Esfahani S, Ingold Heppner B, Klauschen F, Furlanetto J, Pfitzner B, Huober J, Schmitt W, Blohmer J-U, Kümmel S, Engels K, Lederer B, Schneeweiss A, Hartmann A, Jakisch C, Untch M, Hanusch C, Weber K, Loibl S. Evaluation of tumor-infiltrating lymphocytes (TILs) as predictive and prognostic biomarker in different subtypes of breast cancer treated with neoadjuvant therapy - A metaanalysis of 3771 patients [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr S1-09.

Background The estrogen receptor (ER) as a nuclear transcription factor alters the transcription of estrogen sensitive genes to which the progesterone receptor gene belongs. The ER has also been described to exert non genomic effects by interacting with several cell signalling pathways that do not initially involve increases in gene transcription. These different patterns of action of the ER lead to the assumption that in tumors that utilize the non-genomic ER activity in order to stimulate tumorigenesis and proliferation progesterone receptor (PgR) expression would be decreased or absent. Therefore lack of PgR expression could be a surrogate marker of altered growth factor signalling. The aim of this study was to investigate if PgR expression may act as a predictive factor for response to neoadjuvant chemotherapy and long-term outcome in breast cancer patients. Methods 5613 patients with primary breast cancer, follow-up, positive ER expression; HER2+ and HER2- from overall 10 (n=9785) German neoadjuvant trials receiving an anthracycline and taxane based chemotherapy were included. The pathologic complete response (pCR)(ypT0, ypN0), long term survival data (disease free survival (DFS), distant disease free survival (DDFS), overall survival (OS) and local recurrence free survival (LRFS)) and early relapse, defined as DFS Results Tumors lacking PgR expression (1172 patients) were more often of grade 3 (38.4% v 26.3%; p pCR rates were significantly higher in PgR negative patients in the entire cohort (13.8% v 7.5%; p PgR negativity was also significantly associated with an early relapse overall (32.8% v 25.7%; p Patients with PgR negative disease had a significantly worse DFS, OS, DDFS and LRFS (p Conclusion This analysis demonstrates that ER positive and PgR negative tumors represent a specific subset in primary breast cancer patients associated with higher response but also worse long term outcome after neoadjuvant chemotherapy. Interestingly, PgR negativity served as an independent predictive factor for achieving a pCR after neoadjuvant chemotherapy and therefore its status should be considered when deciding on systemic treatment. Citation Format: van Mackelenberg M, Denkert C, Nekljudova V, Karn T, Schem C, Marme F, Stickeler E, Jackisch C, Hanusch C, Huober J, Fasching P, Blohmer J-U, Kümmel S, Müller V, Schneeweiss A, Untch M, von Minckwitz G, Weber K, Loibl S. Outcome after neoadjuvant chemotherapy in progesterone receptor negative breast cancer patients – A pooled analysis of individual patient data from ten prospectively randomized controlled neoadjuvant trials [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P1-09-11.

Introduction Addition of carboplatin to anthracycline/taxane-based neoadjuvant chemotherapy has shown to improve pathological complete response (pCR; ypT0 ypN0) rates in patients with triple-negative breast cancer (TNBC) in two large phase II studies (GeparSixto: von Minckwitz et al, Lancet Oncol 2014, CALGB 40603: Sikov WM, J Clin Oncol 2015). Participants of the GeparSixto study showed an improvement of pCR rate from 36.9 to 53.2% (p=0.005) and DFS by absolute 9% (HR 0.56 95% CI 0.33-0.96] p=0.035) with the addition of carboplatin in the TNBC subgroup. No effect was observed in the HER2-positive subgroup. We here report results on homologous repair deficiency (HRD) status in relation to pCR and DFS in the TNBC subgroup. Patients and Methods In the GeparSixto trial (NCT01426880), patients were treated for 18 weeks with paclitaxel 80mg/m2 q1w and non-pegylated-liposomal doxorubicin (NPLD) 20mg/m2 q1w. Patients with TNBC (N=315) received concurrently bevacizumab 15mg/kg i.v. q2w until surgery. All patients were randomized 1:1 to receive concurrently carboplatin AUC 1.5-2 q1w vs no carboplatin. Carboplatin dose was reduced from AUC 2.0 to 1.5 by an amendment after 330 patients. Primary objective is pCR rate (ypT0 ypN0). Event free survival (EFS), and overall survival (OS) were secondary objectives. HR Deficiency status was assessed on FFPE material from pretherapeutic core biopsies. HR Deficiency was defined as either HRD score high or a BRCA mutation. Results HRD status was measurable in 193 of 315 TNBC patients. 101 patients of them were randomly assigned to receive carboplatin and 92 to no additional carboplatin. After median follow-up of 34.3 months 43 event free survival (EFS) events have been reported. HR deficiency was detected in 136 (70.5%) tumors of which 79 (58.1%) showed high HRD score with intact tBRCA. HR deficiency independently predicted pCR (ypT0is ypN0) (odds ratio (OR) 2.506, CI 1.243-5.051, p=0.009). Adding carboplatin to PM significantly increased the pCR rate from 36.6% to 63.2% in HR deficient tumors with intact tBRCA (p=0.018), only marginally from 61.9% to 72.7% in BRCA mutated tumors (p=0.406), and moderately from 20.0% to 40.7% in HR non-deficient tumors (p=0.086). In general, patients with HRD deficient tumors had a better ESF than non HRD deficient ones (HR 1.805 (0.985-3.309); p=0.0526). Patients with high HRD score had an insignificant trend towards an improved EFS compared to those with low HRD score (HR 1.546 (0.764-3.127) p=0.2223). HRD deficiency did not predict carboplatin effect in patients without BRCA mutation (HR 0.8617). In multivariable analysis, only therapy, clinical nodal status before treatment, and lymphocyte predominant breast cancer were significant prognostic on EFS. Conclusion Within the GeparSixto study HR deficiency (either HRD score high or BRCA mutation) was associated with a higher pCR in general and an improved EFS. The effect of carboplatin could not be predicted by HR deficiency in this relatively small study. However, the results will help to understand the role of HR deficiency and the value of the HRD score in TNBC especially in patients without BRCA mutation. Citation Format: von Minckwitz G, Timms K, Untch M, Elkin EP, Hahnen E, Fasching PA, Schneeweiss A, Salat CT, Rezai M, Blohmer J-U, Zahm D-M, Jackisch C, Gerber B, Klare P, Kümmel S, Paepke S, Schmutzler R, Chau S, Reid J, Hartman A-R, Nekljudova V, Weber KE, Loibl S. Homologous repair deficiency (HRD) as measure to predict the effect of carboplatin on survival in the neoadjuvant phase II trial GeparSixto in triple-negative early breast cancer [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P1-09-02.

Background: The GeparSepto (NCT01583426) study showed that nab-paclitaxel (nP) increases the pathological complete response (ypT0 ypN0) rate when it replaces paclitaxel (P) as part of a sequential taxane followed by epirubicin/cyclophosphamide (EC) neoadjuvant chemotherapy for pts with early breast cancer (BC) (Untch Lancet Oncol 2016). After a safety analysis showed a higher rate of dose reductions, treatment discontinuations as well as peripheral sensory neuropathy (PSN) with nP 150 mg/m2 w (nP150) compared to P 80mg/m2 w, dose of nP was reduced to 125 mg/m2 w (nP125). The risk-benefit ratio of nP125 was improved over nP150 (von Minckwitz SABCS 2015). We reported follow-up (FU) data on PSN occurrence and resolution. Methods: Pts with untreated BC received P 80mg/m2 w or nP 150/125mg/m2 w followed by four cycles of E 90 mg/m2 plus C 600 mg/m2 q3w, with trastuzumab 6 mg/kg (loading (LD) dose 8 mg/kg) and pertuzumab 420 mg (LD 840 mg) q3w if HER2+. After the end of the study the protocol was amended in order to collect long-term data on PSN outcome as well as on treatment modalities. PSN will be reported according treatment and dose received on day 1. Results: Overall 601 pts received P80; 220 pts nP150 and 385 pts nP125 on day 1. PSN grade 2-4 was observed in 18.8% (n=113/601) of pts treated with P80 and in 41.8% (n=92/220) vs 39.2% (n=151/385) with nP150 and nP125 respectively (p=0.547). Grade 3-4 PSN was reported for 2.7% (n=16/601) of pts in the P80 group and 14.5% (n=32/220) vs 8.1% (n=31/385) in the nP150 vs nP125 group respectively (p=0.018). In 31.8% (36/113), 35.9% (33/92) and 27.2% (41/151), PSN was not resolved at the end of the treatment (EOT); PSN grade 3-4 was not resolved in 37.5% (6/16), 56.3% (18/32) and 58.1% (18/31). After a median FU of 110 weeks after EOT, data on PSN status for pts with unresolved PSN grade 2-4 were available from 30, 22 and 32 pts; 26 pts did not provide update information (n=7 died, n=5 data not yet available, n=14 status unknown). For 63.3% (n=19), 40.9% (n=9) and 56.2% (n=18) of pts, PSN grade 2-4 was resolved to grade 1. Time to resolve (TTR) of PSN grade 2-4 was significantly different between nP150 and nP125 (p Conclusions: nP125 is associated with a lower occurrence of PSN compared to nP150 but higher PSN than P80. If PSN occurred nP125 is associated with a more rapid resolution compared to nP150. Nearly 10.7% had no resolution of PSN so far. Further FU and markers for selecting pts at risk are needed. The trial is supported by Celgene. Table 1. Median time to resolution (mTTR) of PSN to grade 1comparison groupsmTTR n (weeks); [95% CI]P vs nPPnP150nP125grade 2-47 [6-9]8 [6-10]grade 3-49 [4-15]17 [5-123]nP150 vs nP125 grade 2-4 13 [9-15]6 [4-9]grade 3-4 56 [11-170]17 [10-nr]abbreviations: nP, nab-paclitaxel; P, paclitaxel; nr, not reached Citation Format: Furlanetto J, von Minckwitz G, Jackisch C, Schneeweiss A, Aktas B, Denkert C, Wiebringhaus H, Kuemmel S, Warm M, Paepke S, Just M, Hanusch C, Hackmann J, Blohmer J-U, Clemens M, Costa SD, Gerber B, Nekljudova V, Untch M, Loibl S. Peripheral sensory neuropathy occurrence and resolution: Results from the neoadjuvant randomized GeparSepto study (GBG 69) [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P5-16-03.

Introduction The GeparSepto study showed that the substitution of paclitaxel (P) with nab-paclitaxel (nP) followed by epirubicin/cyclophosphamide (EC) as neoadjuvant chemotherapy increased the rate of pathological complete response (pCR) from 29% to 38% (p Patients and Methods In the GeparSepto trial (NCT01583426) patients were randomized in a 1:1 ratio to receive either nP 125mg/m2 or P 80 mg/m2 q1w for 12 weeks followed by 4 cycles of conventionally dosed EC (E: 90mg/m2; C: 600 mg/m2) q3w (Furlanetto et al. Annals Oncol 2016). Patients with HER2+ tumors received trastuzumab 6(8)mg/kg q3w and pertuzumab 420(840)mg q3w concomitantly to all chemotherapy cycles (Loibl et al. Annals Oncol 2016). Patients with untreated, histologically confirmed uni- or bilateral, cT2- cT4d breast carcinoma, and no clinically relevant cardiovascular and other co-morbidities were included. Primary objective was pCR rate (ypT0 ypN0). Secondary objectives were invasive disease-free survival (IDFS), and overall survival (OS) overall and according to stratified subpopulations, amongst other time to event endpoints, quality of life focusing on peripheral sensory neuropathy (PNP), treatment of PNP, and cardiac toxicity, detection of circulating tumor (ct) DNA at the time of surgery and during follow up and correlation with pCR and early relapses. The IDFS analysis is planned after 248 events have occurred. The log-rank test will have 80% power to detect an improvement of the 5 year IDFS from 75% to 81.8% (HR=0.70) at a 2-sided significance level of α=0.05. Results In 69 German centers, 1229 patients were randomly assigned (07/2012 – 12/2013) to receive either nP (606) or P (600). nP was given for the majority of cycles at a dose of 150mg/m2 to 179 patients and at a dose of 125mg/m2 to 426 patients. Follow-up is still ongoing. The expected number of events will be awaited for October 2017. Conclusion Neoadjuvant GeparSepto study demonstrated a significantly higher pCR rate when patients received nP instead of P as part of an anthracycline/taxane based sequential chemotherapy. The expected long-term results will help to assess the overall benefit of nP in BC and the surrogate value of pCR for survival endpoints. Citation Format: Schneeweiss A, Jackisch C, Schmatloch S, Aktas B, Denkert C, Schem C, Wiebringhaus H, Kümmel S, Rhiem K, Warm M, Fasching PA, Just M, Hanusch C, Hackmann J, Blohmer JU, Gerber B, Furlanetto J, von Minckwitz G, Nekljudova V, Loibl S, Untch M. Survival analysis of the prospectively randomized phase III GeparSepto trial comparing neoadjuvant chemotherapy with weekly nab-paclitaxel with solvent-based paclitaxel followed by anthracycline/cyclophosphamide for patients with early breast cancer – GBG69 [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr GS3-05.

Background: We previously demonstrated that the majority of women ≤45 years experienced chemotherapy-induced ovarian failure (CIOF) after CT for EBC. Age, CT regimen, duration and dose-density influenced the rate of CIOF. The regain of premenopausal Follicle-Stimulating Hormone (FSH) and Estradiol (E2) levels after chemotherapy is not equivalent to fertility restoration. The Anti-Muellerian Hormone (AMH) assessment seems to be more accurate than other hormones in predicting the ovarian reserve. FSH, E2 and AMH have been prospectively assessed in young patients receiving (neo)adjuvant CT. Methods: 740 patients (pts) aged ≤45yrs treated with anthracycline or taxane-based CT for EBC from 4 German neoadjuvant/adjuvant trials were included. Blood samples were collected at baseline before CT (N=740), end of treatment (EOT n=740), 6 (n=177), 12 (n=113), 18 (n=69), 24 (n=47) months (m) after EOT. Only the full set of samples of a given patient was included. FSH, E2 and AMH were centrally assessed. Postmenopausal hormone levels of FSH and E2 according to the central laboratory were defined as FSH>12.4IU/l and E2 Results: Median age was 40yrs (range 21-45); 57.2% had BMI 18.5- Conclusion: Nearly 70% of women regain premenopausal hormone levels of FSH and E2 within 2 years after end of CT. Despite that, only less than one third maintain their fertility potential as predicted by AMH. AMH is a very sensitive marker for the prediction of fertility function after CT for EBC. Table 1 Median and range of FSH, E2 and AMH levels per time pointsTimepointFSH,IU/lE2, ng/mLAMH, ng/ml% of pts with AMH levels above dtBaseline6.0 [dt-142.7]88.0 [dt-2375.0]0.96 [dt-16.18]95.4EOT76.1 [1.9-225.0]dt [dt-632.0]dt [dt -3.11]15.66 m41.4 [1.1-190.6]10.0 [dt-929.0]dt [dt -3.11]26.112 m28.7 [1.1-146.0]11.0 [dt-947.0]dt [dt -2.81]29.218 m20.6 [0.8-172.3]19.0 [dt-624.0]dt [dt -1.89]34.824 m16.30 [dt-93.9]44.0 [dt-11795.0]dt [dt -1.75]38.3Abbreviations: dt, detectable threshold, EOT, end of treatment; m, month; pts, patients. Detectable threshold: FSH Citation Format: Furlanetto J, Thode C, Huober J, Denkert C, Bassy M, Hanusch C, Jackisch C, Kümmel S, Schneeweiss A, Untch M, Fasching PA, Karn T, Marmé F, van Mackelenbergh M, Müller V, Schem C, von Minckwitz G, Strik D, Nekljudova V, Loibl S. Changes in hormone levels (E2, FSH, AMH) and fertility of young women treated with neoadjuvant chemotherapy (CT) for early breast cancer (EBC) [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr PD7-09.

Background Pre-clinical data and initial results from clinical studies point to the added benefit of CDK4/6 inhibition when combined with anti-HER2 tx. The current study is designed to evaluate the added benefit of palbociclib when given in combination with anti-HER2 and endocrine tx maintenance in the 1st†line setting of metastatic HER2+HR+ breast cancer. Trial design PATINA is an international, open-label, pivotal Phase III study. Primary objective is to demonstrate that the combination of palbociclib with anti-HER2 plus endocrine tx is superior to anti-HER2 plus endocrine tx in prolonging PFS. Sample size is 496 pts. The study starts after completion of 6-8 cycles of chemotherapy-containing anti-HER2 tx for metastatic breast cancer in the 1st line setting. Pts are eligible provided they are without evidence of disease progression by local assessment (i.e. CR, PR or SD). To account for the need for less intense tx regimens for a subset of pts diagnosed with HER2+ER+ disease, clinicians may recommend the combination of trastuzumab with either a taxane or vinorelbine prior to study initiation. Clinicians might also choose a non-pertuzumab option for pts previously treated with pertuzumab in the neo(adjuvant) setting. Secondary objectives include measures of tumor control (OR, CBR, DOR), OS, safety and QOL. The translational science main objective is to compare PFS estimates according to PIK3CA mutation status assessed by cfDNA analysis. Endocrine tx options are AI or fulvestrant. Premenopausal pts must receive ovarian suppression. The study has a 90% power to detect a hazard ratio of 0.667 in favor of the palbociclib arm. Pts approached to participate in AFT-38 will be asked to indicate on the informed consent forms whether remaining biospecimens and clinical data from the control arm of the study can be shared with the Mastering Breast Cancer (MBC) Initiative. The overarching purpose of the MBC is to create a mechanism for understanding the natural history of metastatic breast cancer by cataloguing longitudinally studied tumor-specific markers and treatment effects. ClinicalTrials.gov Identifier: NCT02947685 Citation Format: Metzger-Filho O, Mandrekar S, Loibl S, Ciruelos E, Gianni L, Lim E, Miller K, Huang C, Koehler M, Francis P, Valagussa P, Goel S, Prat A, Goetz M, Loi S, Krop I, Carey L, Lanzillotti J, Winer E, Tripathy D, DeMichele A. PATINA: A randomized open label phase III trial to evaluate the efficacy and safety of palbociclib + anti HER2 therapy + endocrine therapy vs anti HER2 therapy + endocrine therapy after induction treatment for hormone receptor positive, HER2 positive metastatic breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr OT3-05-07.

Background: Cell cycle inhibition is a proven target for novel cancer therapeutics. Palbociclib (P) is an orally active inhibitor of CDK4/6, and arrests the cell cycle at the G1-S transition. P in combination with endocrine therapy (ET) has demonstrated efficacy in phase II and III randomized trials for patients with newly diagnosed and recurrent hormone receptor positive/HER2 negative (HR+/HER2-) metastatic breast cancer (MBC), and is approved in these settings. Given confirmed benefits of P and ET for MBC, the PALLAS study was designed to determine if the addition of P to adjuvant ET improves outcomes over ET alone in HR+/HER2- early breast cancer. Trial Design: PALLAS is an international open-label phase III trial randomizing (1:1) patients (pts) to 2 years of P (125 mg daily, 21 days on 7 days off in a 28-day cycle) combined with at least 5 years of provider choice ET (AI, tamoxifen, +/- LHRH agonist), versus ET alone. The primary objective of the study is to compare invasive disease-free survival (iDFS) for the combination of P and ET, versus ET alone. Secondary objectives include comparison of iDFS excluding cancer of non-breast origin, DRFS, LRRFS, OS, as well as safety. The principal objective of the translational investigations is to determine the predictive or prognostic utility of defined genomic subgroups with respect to iDFS and OS. Additional objectives include evaluation of cfDNA and tissue biomarkers predictive of benefit or resistance, pharmacogenomics, adherence, and patient-reported QOL. Eligible pts are pre- or post-menopausal women or men with stage II-III, HR+/HER2- breast cancer. Patients may have already initiated ET, but must be randomized within 12 months of diagnosis and 6 months of initiation of adjuvant ET. Trial sample size is 4600 pts and stage IIA pts will be capped at a total accrual of 1000 pts. Interim analyses for safety, futility/efficacy and sample size re-estimation are planned. PALLAS opened in 9/2015 and accrual is ongoing. Contact information: emayer@partners.org Key words: palbociclib, CDK4/6 inhibition, HR+/HER2- early breast cancer, adjuvant endocrine therapy. Citation Format: Mayer E, DeMichele A, Gnant M, Barry W, Pfeiler G, Metzger O, Burstein H, Miller K, Rastogi P, Loibl S, Goulioti T, Zardavas D, Fesl C, Koehler M, Huang-Bartlett C, Huang X, Piccart M, Winer E, Wolff A. PALLAS: PALbociclib CoLlaborative Adjuvant Study: A randomized phase 3 trial of palbociclib with standard adjuvant endocrine therapy versus standard adjuvant endocrine therapy alone for HR+/HER2- early breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr OT3-05-08.

Background: Although endocrine therapy (ET) is recommended as first-line therapy for hormone receptor (HR)-positive, HER2-negative metastatic breast cancer (MBC) up to 50% of patients receive chemotherapy in this setting. Meanwhile new targeted treatment options for combination with ET have been developed and endocrine-based therapy with the CDK4/6 inhibitor Palbociclib (P) improves the progression free survival (PFS) of ET alone by about 50%. So far, there is no data comparing chemotherapy with or without maintenance ET and ET in combination with P as first-line therapy. Patients included in clinical trials are often criticized not to mirror the general breast cancer population and every-day clinical practice due to rigid inclusion and exclusion criteria, limited number of treatment options, strict monitoring intervals and study assessments. Methods: PADMA trial is a so called low intervention trial with no rigid inclusion and exclusion criteria, and study assessments.Patients with first-line HR+/HER2- MBC who are candidate for mono-chemotherapy will be eligible to receive either P plus ET per label or mono-chemotherapy per investigator´s choice with or without maintenance ET (1:1 randomization). Primary objective is to compare the time-to-treatment failure (TTF) for patients randomized to receive the mono-chemotherapy treatment strategy versus those randomized to receive P and ET. TTF is defined as time from randomization to discontinuation of treatment due to disease progression, treatment toxicity, patient's preference, or death. Main secondary objectives are progression free survival, overall survival at 36 months, amongst other time to event endpoints as well as toxicity and compliance. All patients receive a specific mobile device (PADMA-Phone) and a validated wearable device (ActiWatch) in order to collect data regarding sleep and activity levels, patient well-being and health care utilization (number and duration of phone calls, and patient visits to investigator site) for assessment of daily monitoring treatment impact (DMTI). Results: Overall, 360 patients will be accrued to show an improved TTF for P in combination with ET compared to mono-chemotherapy of investigator´s choice with or without maintenance ET. Recruitment will start in QIII/2017 and is planned for approximately 18 months in 100 sites in Germany, Spain, Poland, Italy, France, UK and Canada. Conclusions: The aim of PADMA is to demonstrate that an endocrine-based strategy consisting of ET plus P is superior to a chemotherapy-based strategy as first-line therapy in women with HR+/HER2- MBC in a real world setting. Assessment of patient-reported outcome, health care utilization, and sleep and activity levels will deliver important information on the differences between endocrine-based and chemotherapy-based treatment. Citation Format: Loibl S, Barinoff J, Seiler S, Decker T, Denkert C, Hardy-Bessard A-C, Senkus-Konefka E, Cognetti F, Palmieri C, Gelmon K, Luebbe K, Furlanetto J, Mueller V, Mundhenke C, Schmidt M, von Minckwitz G, Uhlig M, Burchardi N, Thill M. A randomized, open-label, multi-center phase IV study evaluating palbociclib plus endocrine treatment versus a chemotherapy-based treatment strategy in patients with hormone receptor-positive, HER2-negative metastatic breast cancer in a real world setting (PADMA) [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr OT3-05-04.

Background: We previously reported that nab-paclitaxel (nP) increases the pathological complete response (pCR, ypT0 ypN0) rate when it replaces solvent-based paclitaxel (P) as part of a sequential taxane followed by epirubicin/cyclophosphamide (EC) neoadjuvant chemotherapy for patients with early breast cancer (Untch et al. SABCS 2014). Here, we report efficacy and safety of patients being treated either with 150 mg/m2 nab-paclitaxel (nP150) before an amendment or with 125 mg/m2 nab-paclitaxel (nP125) thereafter in comparison to solvent-formulated paclitaxel at 80 mg/m2 (P80). Methods: In the GeparSepto study (NCT01583426), 1207 patients were randomized to either nP150 or P80 q1w for 12 weeks followed by 4 cycles of conventionally dosed EC (E: 90mg/m2; C: 600 mg/m2) q3w. The primary objective of the study was to compare the pCR rate (pCR, ypT0 ypN0). Patients with untreated, histologically confirmed uni- or bilateral, cT2- cT4d carcinoma, and no clinically relevant cardiovascular and other co-morbidities were included. Patients with HER2+ tumors received trastuzumab (loading dose 8mg/kg; 6 mg/kg) plus pertuzumab (loading dose 840 mg; 420 mg) q3w concomitantly to all chemotherapy cycles. After a safety analysis showed a higher rate of dose reductions and treatment discontinuations with nP150 compared to P80, weekly dose of nP was reduced to 125 mg/m2. Results: nP was given for the majority of cycles at a dose of 150 mg/m2 to 179 patients and at a dose of 125 mg/m2 to 426 patients. Treatment characteristics were fairly balanced between these two sequential cohorts as well as compared to 601 patients receiving P80 except for HER2 status (HER2-positive: nP150 22%, nP125 37% and P80 33%) and Ki67 ( Conclusions: Risk-benefit ratio of nP125 was improved over nP150 with better drug adherence and RTDI, lower frequency of PNP but a higher pCR rate. It should therefore be considered as the preferred schedule when nP is used as neoadjuvant treatment for primary breast cancer. The trial was financially supported by Celgene and Roche. Citation Format: von Minckwitz G, Untch M, Jakisch C, Schneeweiss A, Conrad B, Aktas B, Denkert C, Eidtmann H, Weibringhaus H, Kümmel S, Hilfrich J, Warm M, Paepke S, Just M, Hanusch C, Hackmann J, Blohmer J-U, Clemens M, Costa SD, Gerber B, Nekljudova V, Loibl S. nab-paclitaxel at a dose of 125 mg/m2 weekly is more efficacious but less toxic than at 150 mg/m2. Results from the neoadjuvant randomized GeparSepto study (GBG 69). [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P1-14-11.

Background: The PI3K/Akt/mTOR pathway is frequently activated in breast cancer (BC) and is important for the oncogenic function of HER2. Buparlisib is an oral pan-PI3K inhibitor that targets all 4 isoforms of class I PI3K (a, b, g, d). Clinical activity was observed with buparlisib in patients (pts) with advanced BC as a single agent, and in combination with endocrine and anti-HER2 treatment. Methods: NeoPHOEBE (NCT01816594) is a phase II, randomized, double-blind, parallel-cohort study of neoadjuvant buparlisib/placebo plus trastuzumab and weekly paclitaxel in women with, untreated primary HER2-positive BC. Pts were stratified upfront into 2 independent cohorts according to PIK3CA mutation status. Other eligibility criteria: tumor size >2 cm; unilateral disease; available tumor tissue for central review of estrogen receptor (ER), HER2 status, and PIK3CA genotype; known PIK3CA mutation status; and ECOG PS ≤1. Pts in each cohort (PIK3CA mutant or wild-type [wt]) were randomized (1:1) to receive continuous daily buparlisib (100 mg) or placebo and weekly trastuzumab (4 mg/kg loading dose then 2 mg/kg) for 6 weeks, followed by continuous daily buparlisib (80 mg) or placebo with weekly trastuzumab (2 mg/kg) and weekly paclitaxel (80 mg/m2) for 12 weeks. Study treatment was followed by surgery. Stratification at randomization was based on PIK3CA (mutant vs wt) and ER (positive vs negative) status. The primary endpoint was pathologic complete response (pCR; ypT0) rate at time of surgery. The key secondary endpoint was objective response rate (ORR) at the end of week 6. Other secondary endpoints included pCR by other definitions, ORR prior to surgery, pCR and objective response by ER status, percent of pts with node-negative disease at surgery, rate of breast conserving surgery, and safety, as well as pCR by PTEN expression, Ki67 level, apoptosis rates, percentage of tumor infiltrating lymphocytes (TIL), and by phenotype of 50% TIL at baseline. The sample size is based on a minimax 2-stage randomized phase II design with a prospective control. This design allowed for early stopping if the desired efficacy was not observed after stage 1. Both cohorts were powered (80%) to detect a clinically meaningful increase in pCR of 18% at a one-sided significance level (α=0.15). Results: Between 9/2013 and 10/2014 50 pts were randomized in 38 sites in 4 countries. Recruitment was suspended due to toxicity in 10/2014. Median age was 50 years, 42 pts had a PIK3CA wt and 8 a PIK3CA mutant tumor, 62% of pts presented with HER2+/ER+, 90% with ductal or ductal-lobular invasive, and 62% with G3 tumors; 86% had Ki67 >20%; 9 pts reported a serious adverse event including 3 pts with hepatotoxicity. Overall 14/50 (28 %) pts developed grade 3-4 liver enzyme elevation, of whom 9 (64%) recovered to at least grade1. Final safety and efficacy data on the primary endpoint (pCR) and biomarker data will be presented at the meeting. Conclusions: The NeoPHOEBE study investigates for the first time the efficacy of adding a pan-PIK3 inhibitor to a taxane/trastuzumab-based neoadjuvant therapy in pts with primary HER2-positive BC with or without a PIK3CA mutation. Citation Format: Loibl S, de la Pena L, Nekljudova V, Zardavas D, Michiels S, Denkert C, Rezai M, Bermejo B, Lee S-C, Turri S, Urban P, Kümmel S, Lux M, Piccart M, von Minckwitz G, Baselga J, Loi S. Phase II, randomized, parallel-cohort study of neoadjuvant buparlisib (BKM120) in combination with trastuzumab and paclitaxel in women with HER2-positive, PIK3CA mutant and PIK3CA wild-type primary breast cancer – NeoPHOEBE. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P1-14-01.

Background: The BRCA1-like copy number (CN) profile can be used as a biomarker to predict which stage III breast cancer patients benefit from myeloablative, DNA double-strand-break (DSB)-inducing chemotherapy. In addition, a BRCA1-like gene expression classifier, derived from the BRCA1-like CN profile, can predict which patient group will achieve an increased pathological complete remission rate on a standard neoadjuvant regimen complemented with carboplatin/veliparib. A non-myeloablative, dose-dense schedule of epirubicin, paclitaxel and cyclophosphamide (ETC) is used in the clinic to treat stage III patients. Since ETC contains an intensified dose of DNA DSB-inducing cyclophosphamide, we tested the BRCA1-like CN profile as a predictive biomarker for ETC benefit in the GAIN trial. Methods: The GAIN trial was a prospective, multi-center, non-blinded, randomized phase III trial. Eligibility comprised histologically confirmed invasive breast cancer with at least one positive axillary or internal mammary lymph node and no signs of distant metastases. The allocated adjuvant treatment was intensified chemotherapy with sequential E (150 mg/m2), T (225 mg/m2) and C (2500, after amendment 2000 mg/m2) each 3 cycles every 2 weeks (ETC) or concurrent E (112.5 mg/m2) and C (600 mg/m2) for 4 cycles every 2 weeks followed by 10 cycles of weekly T (67.5 mg/m2) combined with 4 cycles of capecitabine (2000mg/m2) on day 1-14 in a 3-weekly cycle (EC-TX). Only the triple negative patients were used for these analyses. For samples with good quality DNA extracted from formalin-fixed paraffin-embedded tumor tissue, a library was prepared and sequenced on an Illumina HiSeq2000 platform. Copy number estimates were extracted from the sequence data by normalizing GC-content and mappability corrected read counts to the average read count. These CN profiles were classified as either BRCA1-like or non-BRCA1-like using a previously established shrunken centroid classifier with an established cut-off. Disease-free survival (DFS) and overall survival (OS) were estimated using the Kaplan-Meier method, the difference in survival was analysed using log-rank tests. Multivariate analyses were done by generating Cox regression models with important prognostic factors. Results: Out of 424 triple negative patients, 166 patients with available tissue and a tumour cell content of at least 60% were analysed for BRCA1-like status and included in the analyses (classified as BRCA1-like: n=122). Based on clinicopathological characteristics, these patients were similar to the total group of triple negative participants. In the BRCA1-like patients, there was no significant difference in DFS or OS between ETC and EC-TX (log-rank tests n.s.). In accordance, Cox regression models confirmed these findings. Conclusion: In contrast to the predictive value of the BRCA1-like profile in myeloablative chemotherapy, it could not predict survival benefit for a non-myeloablative, non-platinum-/veliparib-containing regimen in this study population. An intensified dose of cyclophosphamide resulted in similar outcomes in BRCA1-like patients as addition of capecitabine to standard chemotherapy. These results help to define the appropriate application of the BRCA1-like profile as a predictive biomarker. Citation Format: van Rossum AGJ, Schouten PC, Weber KE, Nekljudova V, Denkert C, von Minckwitz G, Karn T, Möbus VJ, Linn SC, Loibl S, Marmé F. BRCA1-like profile as predictive biomarker in non myeloablative chemotherapy (GAIN study). [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P3-07-28.

Background: Phosphatidylinositol 3-kinase mutations (PIK3CA) are common in breast cancer (BC). Mutations are predominantly found in hot-spots located in the helical and kinase domains (exons 9 and 20). We recently demonstrated that PIK3CA mutations predict lower pathological complete response (pCR) to double blockade with trastuzumab/lapatinib in HER2+ve primary BC. Methods: We evaluated PIK3CA mutations in 293/403 HER2+ve tumors of participants of the neoadjuvant GeparSepto (G7) study (Untch et al. SABCS 2014). The G7 study investigated the effect of exchanging paclitaxel for nab-paclitaxel prior to EC. All patients received trastuzumab and pertuzumab. The G7 study showed a significantly higher pCR rate in patients receiving nab-paclitaxel. HER2, hormone receptors (HR), Ki67 and tumor infiltrating lymphocytes (TILs) were centrally assessed prior to randomization. PIK3CA mutations in exons 9 and 20 were evaluated in formalin-fixed, paraffin embedded core biopsies taken before therapy using deep targeted massive parallel sequencing with a minimum coverage of 500 and a mean coverage of 6520 and 6346 per amplicon, (exon9 and exon 20). Only non-synonymous mutations in the coding region that were called at variant allele frequency ≥10% were taken into consideration. Only cases with a tumor cell content of ≥20% were included. Results: In the G7 study, 396 patients with HER2+ve BC have been randomized from 06/2012 to 01/2014 and started treatment. From these 293 could be sequenced. Median age in the analyzed cohort was 49 years (range 22-75); most tumors were cT1-2 (89.9%); cN0 (54.4%); ductal invasive (88.7%), grade 3 (53.9%), HR+ve (69.6%), Ki67>20% (69.3%), LPBC-negative (83.2%). Overall, 22.2% of the tumors were found to have a PIK3CA mutation, 20.1% in HR+ve and 27.0% in HR-ve. Overall, the pCR rate was significantly lower in the PIK3CA mutant tumors compared to the wild type (wt) group (47.7% vs. 66.7%; p=0.009). This effect was seen both in the HR+ve (43.9% vs. 61.3%; p=0.052) and the HR-ve population (54.2% vs. 80.0%; p=0.029). There was also a significant difference in pCR according to PIK3CA mutation status dependant on the taxane. In the nab-paclitaxel group, pCR rates were significantly lower in patients with PIK3CA mutations compared to those without PIK3CA mutations (38.7% vs. 72.0%; p=0.001), whereas in the paclitaxel group, there was no significant difference between patients with and without a PIK3CA mutation (55.9% vs. 60.9%; p=0.690). The respective interaction could be demonstrated in univariate (p=0.039) as well as multivariate regression analysis (p=0.010) after adjusting for known baseline factors. Conclusion: Patients with PIK3CA mutant HER2+ve BC have a significantly lower pCR rate compared to patients with wt tumors. In contrast to the results with double anti-HER2 blockade consisting of trastuzumab/lapatinib, the effect was evident irrespective of the HR status. In addition, PIK3CA mutation status was significantly associated with higher pCR following nab-paclitaxel. The project has partly been funded within the EU-FP7 project RESPONSIFY No 278659 and the German Cancer Consortium (DKTK). Citation Format: Loibl S, Budczies J, Weichert W, Furlanetto J, Stenzinger A, Pfarr N, von Minckwitz G, Jackisch C, Schneeweiss A, Fasching P, Schmatloch S, Aktas B, Nekljudova V, Weber K, Untch M, Denkert C. PIK3CA mutations predict resistance to trastuzumab/pertuzumab and nab-paclitaxel in primary HER2-positive breast cancer – Massive parallel sequencing analysis of 293 pretherapeutic core biopsies of the GeparSepto study. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P3-07-03.

Background: In routine clinical practice chemotherapy (CT) doses are frequently capped at a body surface area (BSA) of 2.0 m2 or adjusted to an ideal weight (i.e. [body length in cm - 10%] + 40% [current weight-ideal weight]) for obese patients (BMI>30 according to WHO) due to safety reasons. There are no data on CT dosing within intense dose-dense regimen for obese patients. Therefore, a retrospective analysis of the GAIN study population has been conducted. Methods: Between August 2004 and July 2008 a total of 3023 patients were enrolled in the GAIN study, a randomized phase III adjuvant trial, comparing two types of dose-dense regimen. Patients were randomized to intense dose-dense ETC (Epirubicin 150 mg/m2, Paclitaxel 225 mg/m2, Cyclophosphamide 2500-2000 mg/m2, i.v. q15 for 3 cycles) or EC followed by T plus capecitabine (X) (EC-TX) (E 112.5 mg/m2 + C 600 mg/m2, i.v. q15 for 4 cycles followed by T 67.5 mg/m2 i.v. q8 for 10 weeks + X: 2000 mg/m2 p. o. day 1-14, q22 for 4 cycles). An adjustment of CT dose to an ideal weight for obese patients was implemented by a protocol amendment. Yet some patients received a dose adjustment by capping at 2.0 m2. We retrospectively evaluated a total of 543 patients with a BMI>30. Data on BSA and dose adjustment were collected from case report forms. Toxicities were compared between patients who received CT according to an unadjusted or adjusted BSA using the 2-sided exact test of Fisher. Disease-free survival (DFS) and overall survival (OS) were calculated using the Kaplan-Meier method and the log-rank test. Results: Overall, 18.0% (n=543) of patients in the GAIN study were obese: 30.9% (n=168) of them received CT according to an unadjusted BSA. For the remainder BSA was adjusted to ideal weight or was capped at 2.0 m2 (69.1%; n=375). A total of 14.5% (n=24) of obese patients receiving full dose of chemotherapy vs 6.4% (n=24) of obese patients with an adjusted BSA experienced febrile neutropenia (p=0.005) and 9.6% (n=16) vs 2.9% (n=11) high grade thrombopenia (p=0.002). Overall, 16.7% (n=28) vs 10.1% (n=38) had a thromboembolic event (p=0.034), which was high grade in 12.5% (n=21) vs 6.4% (n=24), respectively (p=0.027) and 3.0% (n=5) vs 0.3% (n=1) experienced high grade hot flushes (p=0.012). The only significant differences in favor of the non-adjusted group were for dizziness (4.2% [n=7] vs 10.7% [n=40]; p=0.013), diarrhea (18.5% [n=31] vs 26.9% [n=101]; p=0.039) and an increase in serum creatinine (6.8% [n=11] vs 14.0% [n=52]; p=0.019). No differences in DFS and OS were observed between the two groups (5year DFS 81.9% [CI 74.9%-87.2%] vs 80.8% [76.3%-84.6%]; p=0.850; 5year OS 86.4% [79.9%-90.9%] vs 88.3% [84.4%-91.3%]; p=0.491). Conclusion: This analysis of patients treated with a dose-dense regimen showed that obese patients who received CT according to their real BSA have a higher risk of severe toxicities, in particular of febrile neutropenia, high grade thrombopenia and high grade thromboembolic events. Therefore, a dose adjustment of intense dose-dense CT should be performed for obese patients to avoid life-threatening complications. Citation Format: Furlanetto J, Eiermann W, Marmé F, Reimer T, Reinisch M, Schmatloch S, Stickeler E, Thomssen C, Untch M, Denkert C, von Minckwitz G, Nekljudova V, Loibl S, Möbus V. Higher rate of severe toxicities in obese patients receiving dose-dense chemotherapy according to unadjusted body mass index – Results of the prospectively randomized GAIN study. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P1-13-04.

Background: TNBC patients with homologous recombination (HR) deficient tumors have significantly higher pathologic complete response (pCR, ypT0/is ypN0) rates when treated with platinum-based chemotherapy regimens than TNBC patients whose tumors are HR non-deficient. We performed a pooled analysis of 5 phase II studies that included patients with TNBC treated with neoadjuvant platinum-based chemotherapy to better estimate the pCR rates amongst HR deficient and HR non-deficient tumors. Methods: Patients with TNBC and known HR deficiency status from the following clinical trials were available for analysis: PrECOG 0105 (N=72), NCT00148694/NCT00580333 (N=50), NCT01372579 (N=26), TBCRC 008 (N=18). Neoadjuvant chemotherapy regimens included 1) carboplatin, gemcitabine, iniparib, 2) cisplatin with or without bevacizumab 3) carboplatin, eribulin, 4) carboplatin, nab-paclitaxel, with or without vorinostat. HR deficiency status was defined as a high HRD score (42 or higher) and/or presence of a BRCA1/2 tumor mutation (tBRCA). Logistic regression models were used to adjust for study effects. The addition of data from the TNBC platinum-treated arm of GeparSixto (n=101) to this pooled analysis will be available at the time of presentation bringing the total sample size to 267. Results: pCR was achieved in 51 patients (31%) and 104 patients (63%) were HR deficient (31 with high HRD score and tBRCA mutation, 67 with high HRD score only, and 6 with tBRCA mutation only). Patients with HR deficient tumors were more likely to achieve a pCR than those with HR non-deficient tumors: 44% vs. 8% (p Likelihood of pCR adjusting for studyModel #Predictor VariablePopulation (n)Adjusted Odds RatioLower 95% CIUpper 95% CIP Value1HR DeficiancyAll (166)12.54.237.3 Conclusion: HR deficiency status is a robust predictor of pCR across different neoadjuvant platinum-based regimens. This pooled analysis suggests that HRD can be used to identify TNBC patients with a high probability of obtaining pCR with a platinum-based neoadjuvant chemotherapy regimen. Citation Format: Telli ML, McMillan A, Ford JM, Richardson AL, Silver DP, Isakoff SJ, Kaklamani VG, Gradishar W, Stearns V, Connolly RM, Loibl S, Elkin EP, Timms K, Hartman A-R, von Minckwitz G. Homologous recombination deficiency (HRD) as a predictive biomarker of response to neoadjuvant platinum-based therapy in patients with triple negative breast cancer (TNBC): A pooled analysis. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P3-07-12.

Background: The incidence of brain metastases (BM) in breast cancer patients is rising and has become a major clinical challenge. So far, limited therapeutic options and insights into the biology of BM exist since only a few studies analyzed exclusively data of breast cancer patients. In order to improve this situation, our multicenter registry was initiated in 2014: Brain Metastases in Breast Cancer Network Germany (BMBC, GBG79). Materials and Methods: Patients with BM diagnosed since 2000, a history of breast cancer and no history of other malignant or neurologic disease can be included. Registration is allowed retrospectively as well as prospectively into a web–based database ("MedCodes"). Characteristics of the primary tumor, metastatic disease and BM as well as treatment details are documented. For this first analysis, 548 patients from 39 German centers were included. Results: Median age at first diagnosis of BM was 55 years (25 – 90 years). 43% of patients (233/548) were HER2 positive, 19% (n=105) were triple–negative and 25% (n= 138) had luminal primary tumors indicating a selection of patients with specific tumor biology who develop BM. 54 % of the patients (n=267) had up to three BM whereas 45% (n=223) had more than three BM. 19% of patients (n=106) had BM without evidence of extracranial disease. 27% of the patients (n=146) underwent surgery of the BM. Of these patients, 61% (n= 89) were treated with whole brain radiotherapy and 16% (n=23) with stereotactic radiotherapy. In patients without surgery (n=397), 73% (n=289) received whole brain radiotherapy and 7% (n=28) stereotactic radiotherapy. Median time from diagnosis of primary breast cancer to BM was 38.5 month for the entire cohort (CI95% 35.4 – 43.3). The time from first diagnosis to BM was shorter for triple–negative patients (20.9 month, CI95% 15.5 – 25.9) compared with patients with HER2–positive (37.0 month, CI95% 30.5 – 42.0) or luminal tumors (48.3 month, CI95% 38.2 – 54.0) (p Conclusion: This is so far the largest analysis of breast cancer patients with BM treated in Germany. In this cohort, triple–negative subtype or more than three BM were associated with shorter survival from the diagnosis of BM. HER2 positive patients with no HER2 directed therapy after the diagnosis of BM showed a shorter survival. The recruitment of the registry is ongoing and we aim to include more than 1000 patients by the end of 2015. Citation Format: Witzel I, Loibl S, Laakmann E, Augustin D, Flock F, Dohmen H-H, Durmus G, Frank M, Hesse T, Ignatov A, Kühn T, Neunhöffer T, Park-Simon T-W, Schmidt M, Stefek A, Weide R, Würschmidt F, Fehm T, Moebus V, von Minckwitz G, Burchardi N, Mueller V. Brain metastases in breast cancer network Germany (BMBC, GBG 79): First analysis of 548 patients from the multicenter registry. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P6-17-08.

Background: The epigenetic profile of triple-negative breast cancer (TNBC) showed a wide prevalence of MGMT promoter methylation.Aberrant methylation of MGMT seems to be an independent predictor of poor survival in patients with basal-like breast cancer. Moreover, patients with MGMT-negative basal-like tumors who received cyclophosphamide had asignificantly improved DFS and OS compared with MGMT-positive tumors.However, the impact of MGMT methylation in the context of modern therapy concepts is not clear. Methods: We retrospectively evaluated 174 TNBC tumors of patients enrolled into the neoadjuvantGeparSixtotrial from 08/2011 to 12/2012. Patients were randomized to receive 18 weeks of neoadjuvant treatment with paclitaxel (80mg/m2/week) and non-pegylated liposomal doxorubicin (20mg/m2/week) with or without addition of carboplatin (AUC 2.0-1.5/week).Hormone-receptor status, HER2status, and Ki67 were centrally confirmed prior to randomization. We defined pathological complete response (pCR)as ypT0/is ypN0. MGMT promoter methylation status was determined by PCR using EZ DNA Methylation Kit™ (Zymo Research); TNBCtumors were considered to be methylated if they had an average methylation ≥10%, some tumors were considered borderline due to high heterogeneity among GpC islands.We investigated the effect of MGMT methylation on pCR and its correlation with baseline characteristics. Results: A total of210 tumors from the TNBC cohort of the GeparSixtotrial(n=315) were available with a tumor content >20%. In 174 tumors the methylation assay was performed successfully. The number of tumorswith methylated MGMT was similar in carboplatin vs. non-carboplatin treated cohorts. In the carboplatin group 19.3% (17/88) of TNBC were methylated, 65.5% (58/88)unmethylated, and 14.8% (13/88) borderline.In the non-carboplatin group 20.9% (18/86) of TNBC were methylated, 62.8% (54/86)unmethylated, and 16.3% (14/86) borderline.In the entire cohort,there was no association between MGMT methylation status and pCR (p=0.522).Non-carboplatin cohort: 33.3% (6/18) of patients with methylated MGMT achieved pCR vs. 51.9% (28/54) of unmethylatedand 21.4% (3/14) of borderline (p=0.079).Carboplatin cohort: 52.9% (9/17) of patients with methylated MGMT achieved pCR vs. 55.2% (32/58) of unmethylatedand 76.9% (10/13) of borderline (p=0.320). In TNBC patients with methylated MGMT, the addition of carboplatin resulted in a 20% increased pCR rate (p=0.241). Conclusion: In this study no statistically significant association between MGMT methylation andpCR was found.Patients with MGMT methylation seemed to have a lower possibility to achieve a pCR and the addition of carboplatin seemed to reverse this effect. However, a clear classification of the borderline MGMT samples and further studies in larger series of TNBC are warranted. Citation Format: Fontanella C, Gehlhaar C, Denkert C, Schneeweiss A, Heppner B-I, Koch I, Blohmer J-U, Jackisch C, Lederer B, Fasching PA, Müller V, Untch M, Aprile G, Puglisi F, Nekljudova V, Heppner F, von Minckwitz G, Loibl S. Predictive value of O6-methylguanine-DNA methyltransferase (MGMT) promoter gene methylation in triple-negative breast cancer patients receiving carboplatin. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P3-07-55.

Background: GAIN-2 compares the effectiveness and safety of a predefined intense dose-dense regimen (EnPC) vs. a dose-dense regimen with modification of single doses depending on individual hematological and non-hematological toxicities (dtEC-dtD) (NCT01690702). Moreover, the Trastuzumab substudy compares the subcutaneous administration of the drug to the abdominal wall vs. thigh. Methods: The primary objective of the GAIN-2 trial is to compare the invasive disease-free survival (iDFS) in patients with high-risk primary breast cancer (luminal A ≥4 N+; luminal B N+; HER2+ and TNBC N0/N+). Patients are randomized between EnPC (epirubicin 150 mg/m2 q2w x 3, nab-Paclitaxel 330 mg/m2 q2w x 3, cyclophosphamide 2000 mg/m2 q2w x 3) or dtEC-dtD (dd/tailored epirubicin/cyclophosphamide q2w x 4 followed by dd/tailored docetaxel q2w x 4) Two safety interim analyses after 200 (Noeding et al. Ann Oncol 2014) and 900 patients who have completed chemotherapy were planned. We present the results of the second safety analysis. In addition to the standard analyses for hematological and non-hematological toxicities, any affections of the cranial nerves as well as the rate of macula degenerations and anaphylactic reactions are of special interest. Results: Between 09/2012 and 05/2015 a total of 1473 patients have been randomized (EnPC n=734; dtEC-dtD n=739). Among those, 84 patients have been included in the trastuzumab substudy. No safety data are currently available for the substudy. Median age was 52 years and median body-mass-index 26. In terms of hematological adverse events, the rate of febrile neutropenia grade 3-4 (12% vs. 8%) and thrombopenia grade 3-4 (12% vs. 5%) was significantly increased in the EnPC arm. As for non-hematological side effects, there were significantly more patients developing an increase in alkaline phosphatase (59% vs. 40%), ALAT (69% vs. 59%), peripheral sensory neuropathy (83% vs. 68%), arthralgia (63% vs. 49%), myalgia (48% vs. 41%) and bone pain (25% vs. 17%) in the EnPC arm, whereas nosebleed (10% vs. 25%), edema (13% vs. 26%) and hand-foot syndrome (12% vs. 28%) were more common in the dtEC-dtD arm. We observed two treatment related deaths, both in the dtEC-dtD arm (cause of death: acute respiratory distress syndrome and pneumonia). There were no differences between the treatment arms for the toxicities of special interest. In the EnPC arm, overall 30% of the patients required dose-reductions due to hematological toxicities compared with only 10% in the dtEC-dtD arm (p Conclusion: This interim safety analysis from a prospectively randomized trial investigating iddEnPC with predefined doses and a toxicity adapted idd/tailored strategy (dtEC-dtD) showed no additional or unexpected safety signals in the iddEnPC or dtEC-dtD arm. Therefore, no modifications in the conduction of the study are necessary and the study continues as expected. Citation Format: Möbus V, Lück H-J, Forstbauer H, Wachsmann G, Ober A, Schneeweiss A, Christensen B, von Abel E, Grischke E-M, Höffkes H-G, Klare P, Yon-Dschun K, Schmatloch S, Furlanetto J, Burchardi N, von Minckwitz G, Loibl S. GAIN-2: Adjuvant phase III trial to compare intense dose-dense (idd) treatment with EnPC to tailored dose-dense (dt) therapy with dtEC-dtD for patients with high-risk early breast cancer: Results of the second safety interim analyses. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P1-13-05.

Background: Currently, axillary surgery for breast cancer is considered as staging procedure that does not seem to influence breast cancer mortality, since the risk of developing metastasis depends mainly on the biological behaviour of the primary. Based on this, the postsurgical therapy should be considered on the basis of biologic tumor characteristics rather than nodal involvement. Trial design: The goal of INSEMA is to show that early-stage breast cancer patients with reduced extent of axillary surgery are not inferior regarding invasive disease-free survival (IDFS) outcome. Patients with planned breast-conserving surgery (BCS) will be first randomized (1:4 ratio) to either no axillary surgery or axillary sentinel lymph node biopsy (SLNB). Patients with SLNB and pN+(sn) status will be secondly randomized (1:1 ratio) to either SLNB alone or completion axillary lymph node dissection (ALND) in cases with less than three involved nodes (one or two macrometastases). Primary objective: -IDFS after BCS (non-inferiority question) Inclusion criteria: -Written informed consent -Histologically confirmed unilateral primary invasive carcinoma of the breast (core biopsy) -Age at least 35 years -Preoperative imaging techniques with estimated tumor size of maximal 5 cm (iT1/iT2 irrespective of hormone sensitivity or HER2 status) -Clinically and sonographically tumor-free axilla prior to core biopsy -In cases with cN0 and iN+, a negative core biopsy or fine needle aspiration biopsy of the suspected lymph node is required -No clinical evidence for distant metastasis (M0) -Planned breast-conserving surgery (R0 resection) with postoperative external whole-breast irradiation (conventional fractionation or hypofractionation) Statistics: The calculated total case number for per-protocol analyses is 6,740 (5,940 German and 800 Austrian patients), the expected total number of randomized patients is 7,095. Time lines: -First patient in: September 2015 -Last patient in: August 2019 -Final analysis: End of 2024 Present accrural: In June 2016, more than 1.000 patients were recruited in Germany and Austria. Citation Format: Reimer T, von Minckwitz G, Loibl S, Hildebrandt G, Nekljudova V, Schneider-Schranz C, Gerber B. Comparison of axillary sentinel lymph node biopsy versus no axillary surgery in patients with early-stage invasive breast cancer and breast-conserving surgery: A randomized prospective surgical trial. The Intergroup-Sentinel-Mamma (INSEMA)-trial [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr OT2-04-02.

Introduction Addition of carboplatin to anthracycline/taxane-based neoadjuvant chemotherapy has shown to improve pathological complete response (pCR; ypT0 ypN0) rates in patients with triple-negative breast cancer in two large phase II studies (GeparSixto: von Minckwitz et al. Lancet Oncol 2014; CALGB 40603: Sikov et al. J Clin Oncol 2015). Participants of the GeparSixto study with triple-negative tumors showed an improvement of pCR rate from 36.9 to 53.2% by the addition of carboplatin (p=0.005); however, no statistically significant difference in pCR rate was observed in the HER2-positive subgroup (36.8 vs 32.8%, respectively). A greater benefit with carboplatin was observed in patients with BRCA mutations or a high homologous recombination deficiency (HRD score) in the tumor (pCR rate of 30% compared to 10% for patients without HRD). So far, it is unknown whether these effects on pCR translate into a survival benefit for the patients. We here report an early survival analysis of the GeparSixto study. Patients and Methods In the GeparSixto trial (NCT01426880), patients were treated for 18 weeks with paclitaxel 80mg/m2 q1w and non-pegylated-liposomal doxorubicin (NPLD) 20mg/m2 q1w. Patients with TNBC (N=315) received concurrently bevacizumab 15mg/kg i.v. q2w until surgery. Patients with HER2+ disease (N=273) received concurrently trastuzumab 6(8)mg/kg q3w and lapatinib 750mg daily. All patients were randomized 1:1 to receive concurrently carboplatin AUC 1.5-2.0 q1w vs no carboplatin, stratified by subtype (HER2+ vs TNBC). Carboplatin dose was reduced from AUC 2.0 to 1.5 by an amendment after 330 patients. Primary objective was pCR rate (ypT0 ypN0). Loco-regional invasive recurrence free survival (LRRFS), distant-disease- free survival (DDFS), invasive disease-free survival (IDFS), and overall survival (OS) were secondary objectives. Results 595 patients were recruited (8/2011 - 12/2012) in 51 German centers. 296 patients were randomly assigned to receive carboplatin and 299 to no additional carboplatin, of whom 295 and 293 started treatment, respectively. So far, 82 events have been reported after a median of 28 months follow-up. Analysis of updated events by treatment arm in the full study population as well as in the TNBC and HRD subgroups will be presented. Conclusion Even if the GeparSixto study was not powered to show carboplatin effects on survival, the expected results will help to assess the overall benefit of carboplatin in TNBC and the power of pCR to predict for DFS and OS. Citation Format: von Minckwitz G, Loibl S, Schneeweiss A, Salat CT, Rezai M, Zahm D-M, Klare P, Blohmer J-U, Tesch H, Khandan F, Fasching PA, Jakisch C, Nekljudova V, Untch M. Early survival analysis of the randomized phase II trial investigating the addition of carboplatin to neoadjuvant therapy for triple-negative and HER2-positive early breast cancer (GeparSixto). [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr S2-04.

Background: Cell cycle inhibition is a target of interest for novel cancer therapeutics. Palbociclib (P) is an orally active inhibitor of CDK4/6 which arrests the cell cycle at the G1-S transition. P has demonstrated efficacy in phase II and III randomized trials for first-line and pre-treated hormone receptor positive/HER2 negative (HR+/HER2-) metastatic breast cancer (MBC), with hazard ratios 0.42-0.49 (Finn et al, Lancet Oncol 2015, Turner et al, NEJM 2015), and is approved in combination with letrozole as first-line therapy for HR+/HER2- MBC. Given confirmed benefits of P and endocrine therapy for MBC, the PALLAS study was designed to determine if the addition of P to adjuvant endocrine therapy (ET) improves outcomes over ET alone in HR+/HER2- early breast cancer. Trial Design: PALLAS is an international open label phase III trial randomizing patients to 2 years of P (125 mg daily, 21 days on 7 days off in a 28-day cycle) combined with at least 5 years of provider choice ET (AI, tamoxifen, +/- LHRH agonist), versus ET alone. The primary objective of the study is to compare invasive disease-free survival (iDFS) for the combination of P and ET versus ET alone. Secondary objectives include comparing iDFS excluding cancer of non-breast origin, DRFS, LRRFS, OS, as well as safety. The principal translational science objective is to determine the predictive or prognostic utility of defined genomic subgroups with respect to iDFS and OS. Additional translation objectives include evaluation of tissue and blood biomarkers predictive of benefit or resistance, cfDNA, pharmacogenomics, adherence, BMI, and patient-reported QOL. Eligible patients (pts) may be pre- or post-menopausal, have stage II-III breast cancer, HR+/HER2- by ASCO CAP guidelines, and have recovered from prior therapies. Pts may have already initiated ET, but randomization must occur within 12 months of diagnosis and 6 months of initiation of ET. An FFPE block must be received at the central sample repository for eligibility. Total planned accrual to the trial is 4600 pts, providing 85% power to detect a 25% risk reduction in iDFS from ET alone using a stratified logrank test with an overall one-sided alpha = 0.025. Pts will be randomized 1:1 stratified by stage, receipt of prior chemotherapy, age, and geographic location. Interim analyses for safety, futility/efficacy and sample size re-estimation are planned. PALLAS will open in 9/2015; current accrual will be updated at time of presentation. Citation Format: Mayer E, DeMichele A, Dubsky P, Barry W, Metzger O, Symmans WF, Burstein H, Miller K, Wolff A, Rastogi P, Loibl S, von Minckwitz G, Goulioti T, Zardavas D, Fesl C, Koehler M, Huang Bartlett C, Chen L, Piccart M, Winer E, Gnant M. PALLAS: PAlbociclib Collaborative Adjuvant Study: A randomized phase 3 trial of palbociclib with adjuvant endocrine therapy versus endocrine therapy alone for HR+/HER2- early breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr OT1-03-21.

Background: Ki67 has been suggested as a marker for diagnosis of luminal A and B breast carcinomas. Interestingly, on one hand a multitude of studies have described significant results for Ki67 as a prognostic marker, while on the other hand the analytical validation and standardization of this marker has been a challenge. The best parameter for Ki67 interobserver performance is the interclass correlation coefficient (ICC). ICC values between 0.59 and 0.92 have been reported. Recently a minimum ICC of 0.8 has been suggested as a goal for the international ring trial and as a prerequisite for introduction of Ki67 into clinical practice. However, this suggested ICC is not derived from analysis of data, and the amount of pathologist variance that is allowed for meaningful biomarker results is still not defined. Methods: This study is based on a total of 9069 tumor samples from three large clinical cohorts (IBCSG VIII+IX, BIG1-98, and GeparTrio). In a systematic modeling approach, we introduced different amounts of variance to previously generated central pathology Ki67 datasets by simulation of a total of 1800 different pathologist evaluations for each study cohort. These evaluations were grouped into groups with defined ICCs, ranging from very good concordance (ICC=0.9) to extremely poor concordance (ICC=0.1). For each of the simulated pathologist evaluations, all possible Ki67 cutoffs were systematically evaluated using the web-based software Cutoff Finder (http://molpath.charite.de/cutoff/). As endpoints, we used DFS for all three study cohorts as well as pCR for the neoadjuvant cohort. Results: For the neoadjuvant GeparTrio study, the different groups with ICCs of 0.8, 0.6 and 0.4 showed a very similar performance resulting in significant analyses for prediction of pCR across a wide range of cutoffs. The odd ratios for pCR were slightly lower with lower ICC. Even with an extremely low ICC of 0.2, 99% of the analyses had one or more significant cutpoints. The survival endpoint DFS was shown to be very stable despite increased interpathologist variance in all three clinical cohorts. Even with a poor ICC of 0.4, the majority of cutpoints were significant for DFS. For IBCSG VIII+IX 85% of the analyses with an ICC of 0.4 had one or more significant cutpoints for Ki67. In the large BIG 1-98 dataset (n=6090) even an ICC of 0.2 resulted in one or more significant DFS cutpoints in 100% of the analyses. Comparable results were obtained if the analysis was restricted to luminal tumors. Conclusion: Our results suggest that Ki67 is extremely robust to pathologist variation. Even if less than 40% of the variance is attributable to true Ki67-based proliferation (ICC Citation Format: Denkert C, Budczies J, Regan M, Loibl S, Dell'Orto P, von Minckwitz G, Mastropasqua M, Mehta K, Müller V, Kammler R, Pfitzner BM, Fasching PA, Viale G. Systematic analysis and modulation of Ki67 interobserver variance in 9069 patients from three clinical trials – How much pathologist concordance is needed for meaningful biomarker results?. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P5-07-02.

Background: Lucitanib is a potent, oral inhibitor of the tyrosine kinase activity of Fibroblast Growth Factor Receptors 1-3 (FGFR1-3), Vascular Endothelial Growth Factor Receptors 1-3 (VEGFR1-3) and Platelet-Derived Growth Factor Receptors α/β (PDGFRα/β). FGF aberrancy, as defined by amplification of either FGFR1, or 11q (containing FGF ligands 3, 4, CCND1, and 19), or both, is a hallmark genomic alteration that can be observed in up to 25% of patients with breast cancer. In a phase I clinical trial of lucitanib at daily doses of 5 to 20 mg, heavily pretreated patients with advanced breast cancer patients and FGF aberrancy experienced an objective response rate (ORR) of 50% and a median progression-free survival (PFS) over 9 months (Soria et al, 2014). This compelling clinical activity has led to the initiation of a global clinical development program for lucitanib in breast cancer. Trial design: this is a phase II trial testing the efficacy of lucitanib at the dose of 15 mg daily in patients with ER+/HER2- metastatic breast cancer who have received at least one first-line systemic anticancer therapy in the metastatic setting. After informed consent, metastatic tissue (fresh biopsy or archival) is centrally evaluated by FISH for FGFR1- and/or 11q- amplification. Based on FISH results, patients are allocated to cohort 1 (FGFR1-amp), cohort 2 (11q-amp) or cohort 3 (neither). Patients with dual amplification are allocated to cohort 1. The primary objective is to evaluate the ORR of single agent lucitanib in the three cohorts. Secondary objectives include clinical benefit rate, PFS, safety and pharmacokinetics in addition to exploratory biomarker analyses. A Simon two-stage design will be used for each of the cohorts to test the null hypothesis that the ORR is 5% or less versus 20% using a one-sided test with 5% level of significance and 90% power. In each cohort separately, an initial 21 patients with measurable disease at baseline will be assessed at the end of stage 1. If at least 2 patients respond per the pre-specified criteria, this cohort will accrue additional 20 patients. The null hypothesis will be rejected if there are at least 5 responders among all 41 patients. Eligibility Criteria: ER+/HER2- metastatic breast cancer who have received at least a first line of systemic anticancer therapy and no more than 2 line of chemotherapy with or without targeted therapy in the metastatic setting and have ECOG performance status ≤ 2. Patients with uncontrolled hypertension and at risk of developing hypertension related complications are not eligible. Conclusion: FINESSE is a phase II trial testing lucitanib, a multikinase inhibitor, in three selected populations in order to investigate the ORR in FGFR1 or 11q amplified or non-amplified populations and to explore the role of FGFR1 or 11q amplifications through correlative translational analyses. As of May 21st 2015, 40 patients have been enrolled, 19 of them in the FGFR1-amplified arm. Citation Format: Andre F, Daly F, Azim Jr HA, Agrapart V, Fumagalli D, Gingras I, Guitart M, Lange A, Turner NC, Pierrat M-J, Loibl S, Poirot C, Curigliano G, Loi S, Pallis A, Piccart M, Cortes J. FINESSE - An open, 3-cohort, phase II trial testing oral administration of lucitanib in patients with FGFR1-amplified or non-amplIfied oestrogeN rEceptor poSitive metaStatic breast cancEr. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr OT1-03-03.

Background: The BOLERO-2 study demonstrated a relevant benefit for patients who received everolimus in addition to exemestane in patients who progressed during/after a non steroidal aromatase inhibitor (NSAI), which led to approval of everolimus in this indication. However, in routine use a high rate of intolerability due to side effects is reported. The most common side effect of everolimus is mucositis with a reported high rate of intolerability especially during the first 12 weeks of treatment. Mucositis is also considered to be the leading cause for treatment discontinuation not related to tumor progression. In the neoadjuvant GeparQuinto study, a dose-escalation schema was successfully used to improve tolerability of everolimus together with cytotoxic agents. Methods: DESIREE (NCT02387099) is a randomized, double-blind, phase II study of everolimus in addition to exemestane in patients who progressed during or after NSAI. Patients will be randomized in a 1:1 ratio to receive either everolimus 10 mg/day (week 1-3: 4x2.5 mg/day, blinded; week 4-24: 10mg/day, open according to label) or an escalating dose of everolimus as follows: week 1: 1x2.5 mg verum + 3x placebo/day; week 2: 2x2.5 mg verum + 2x placebo/day; week 3: 3x2.5 mg verum + 1x placebo/day; week 4-24: 10 mg/day (open according to label). The primary aim of the study is to evaluate the incidence of the first episode of mucositis grade 2-4 (WHO's oral toxicity scale) any time during a 12 week period after start of everolimus treatment. Secondary objectives are to compare the cumulative rate of mucositis grade 2-4 at 24 weeks after start of treatment, the cumulative rate of mucositis grade 1 and any grade at 12 and 24 weeks after start of treatment, the rate of patients on 10 mg daily at 12 weeks and 24 weeks after start of treatment, the clinical benefit rate after 24 weeks, safety, time to onset of grade ≥2 mucositis, the cumulative everolimus dose at 4 weeks, the relative dose intensity for everolimus, and quality of life using the FACT-B and the QSDQ questionnaire. Biomaterial (whole blood, serum, plasma and optional primary tumor/metastasis tissue) will be collected to evaluate potential biomarkers predicting safety and compliance. Overall, 156 evaluable patients (78 in each arm) are required to detect a clinically relevant difference of 20% in the mucositis rate between treatment arms using a continuity-corrected χ2-test on a significance two sided level alpha of 0.2 and a power of 90%. The rate was estimated to be 40% and 20% in the control arm and the treatment arm, respectively. Results: The study will be conducted in up to 60 German centers. Recruitment will start in June 2015. Enrollment is planned to be completed within 24 months. Conclusion: The combination of everolimus and exemestane has shown to improve the outcome of patients with metastatic breast cancer. In the DESIREE trial a dose-escalating schema will be employed to enhance patient compliance and tolerability necessary to achieve an adequate dose-intensity. Citation Format: Loibl S, Furlanetto J, Barinoff J, Bauerschlag D, Herr D, Lübbe K, Maass N, Müller V, Mundhenke C, Schmidt M, Schwedler K, Thill M, Gkantiragas I, Burchardi N, von Minckwitz G. DESIREE - A multicenter, randomized, double-blind, phase II study to evaluate the tolerability of an induction dose escalation of everolimus in patients with metastatic breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr OT1-03-08.

Background:The association between pathological complete remission (pCR) in the breast and clinical/pathological parameters is well established, whereas the role of these parameters in the prediction of residual axillary involvement after NACT is unclear. The goal is to identify a subset of patients who do not need axillary treatment. We used data from Arm B of the SENTINA trial to analyze this association. Methods:Patients from arm B of the SENTINA trial with clinically and sonographically unsuspicious axillary nodes but with histologically proven involvement of SLNs prior to NACT were analyzed. All patients had SLNB and axillary dissection after NACT. Univariate analyses were performed to evaluate the association between clinical/pathological parameters and axillary involvement after NACT. Results:Arm B of the SENTINA study contained 360 patients, 318 of which were evaluable with respect to the above parameters. After NACT 71/318 (22.3%) patients had involved SLNs or non-SLNs; 71/318 (22.3%) had a pCR in the breast. We observed a significant association between pCR in the breast and negative ER status, negative PR status, positive HER2 status, triple negative (TN) status, tumor size before and after NACT, multifocality, lobular morphology and axillary involvement after NACT. Regarding residual axillary burden only the associations with lobular morphology, extracapsular invasion, multifocality, positive HER2 status and pCR in the breast were statistically significant. Conclusion:Our analysis demonstrates that patients enrolled in the SENTINA trial with clinically and sonographically unsuspicious axillary nodes but proven histological involvement of SLNs prior to NACT have positive axillary nodes in 22.3 % after NACT. This rate is confirming similar results from other groups. Although we found statistically significant associations between pCR in the breast and clinical/pathological parameters, only the association between lobular type, extracapsular invasion, positive HER2 status and pCR in the breast and residual axillary involvement after NACT were statistically significant. We cannot clearly identify a subset of patients for whom axillary treatment after NACT could be safely omitted if SLNs were positive. Our data are well in line with recently presented data demonstrating that the association between pCR in the breast and free axillary nodes after NACT is particularly strong in patients with TN and HER2 positive tumors. This question will be addressed in future trials currently under development. Citation Format: Kolberg H-C, Liedtke C, Bauerfeind I, Fehm T, Fleige B, Hauschild M, Helms G, Lebeau A, Schmatloch S, Schrenk P, Schwentner L, Stäbler A, Loibl S, Untch M, Kühn T. Residual axillary involvement in early breast cancer in patients with positive sentinel nodes after neoadjuvant chemotherapy (NACT) [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr PD8-02.

Background In the GeparNuevo trial, the PD-L1 inhibitor durvalumab increased the rate of pathologic complete response (pCR; ypT0 ypN0) in triple-negative breast cancer if treatment started in a two-week window before neoadjuvant taxane/anthracycline chemotherapy (61 % pCR vs. 41%; p = 0.048; Loibl et al. ASCO 2018). Overall, pCR rates increased only numerically from 53 % to 44 % (p = 0.281). Herein, we aimed to evaluate the predictive value of PD-L1 immunohistochemistry in pre-therapeutic core biopsies. In addition, we identified dynamics in gene expression using repeated biopsies. Patients and Methods 174 patients were randomized to receive durvalumab or placebo with neoadjuvant chemotherapy. In the window part, 117 patients received a single dose of durvalumab (or placebo) before chemotherapy. Core biopsies were taken at three times: pre-treatment (“A”; N=174), after the window part (“B”; N=88) and after 12 weeks of nab-Paclitaxel (“C”; N=33). PD-L1 immunohistochemistry in A-biopsies (Ventana SP263 Assay) was recorded as percentage of cells with membranous staining in tumor cells and lymphocytes (TILs). We defined a tumor as PD-L1 high if ≥ 25 % of either compartment was stained. Ki-67 was stained on all available A, B and C biopsies (MIB-1, Dako, 1:100) and recorded as the percentage of tumor cells with nuclear staining. We profiled all available biopsies with targeted RNASeq using the HTG EdgeSeq platform (Oncology Biomarker panel, 2560 genes). Sequencing (IonTorrent S5) was successful in 162 A-, 79 B- and 31 C-biopsies. Results PD-L1 expression was high in 24 % of A-biopsies and was predictive for pCR in the complete cohort (OR 2.561; 1.183-5.554; p = 0.017). PD-L1 status of the TILs, but not of the tumor cells, was predictive (OR 1.313; 1.040-1.656; P= 0.022). The effect was not specific for durvalumab treatment. Higher levels of Ki-67 were predictive for pCR in B- biopsies in all patients (OR 1.399; 1.053-1.858; P =0.021) and in the placebo arm, but not in the durvalumab arm. Ki-67 levels in C-biopsies were not predictive; neither was the change in Ki-67 between pre-treatment and later time points (B vs. A or C vs. A). In a differential mRNA expression analysis (A vs. B), we found seven differentially expressed genes after one dose of durvalumab. We observed strong effects on gene expression after taxane treatment (A vs. C), but no significant difference according to treatment. These genes were associated with biological processes involved in therapy response. The pre-treatment levels of 12 of 69 markedly differentially expressed genes were associated with worse response to chemotherapy. Conclusion In A-biopsies, PD-L1 in TILs was predictive for response, and in B-biopsies, Ki-67 was predictive, but neither marker could specifically predict response to durvalumab. We observed limited effects of a single half-dose of durvalumab on global gene expression, but could identify substantial differential expression after taxane treatment. The evaluation of gene expression dynamic offers a promising approach for the identification of resistance-associated markers. The study was financially supported by AstraZeneca and Celgene Citation Format: Sinn BV, Loibl S, Karn T, Untch M, Kunze CA, Weber KE, Treue D, Wagner K, Hanusch CA, Klauschen F, Fasching PA, Huober J, Zahm D-M, Jackisch C, Thomalla J, Blohmer J-U, van Mackelenbergh M, Rhiem K, Felder B, von Minckwitz G, Burchardi N, Schneeweiss A, Denkert C. Pre-therapeutic PD-L1 expression and dynamics of Ki-67 and gene expression during neoadjuvant immune-checkpoint blockade and chemotherapy to predict response within the GeparNuevo trial [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr PD5-05.

Background: CDK4/6 inhibition combined with endocrine therapy (ET) is now the standard of care for advanced hormone receptor (HR) positive breast cancer patients (pts). Previous ctDNA analysis of paired pre-treatment (pre-T) and end of treatment (EoT) plasma samples from the PALOMA-3 trial of the CDK4/6 inhibitor P with/without F demonstrated that acquired PIK3CA, ESR1, RB1 and rare growth factor receptor mutations (mut) likely contribute to resistance (Turner et al, ASCO 2018, Abstract 1001). We now report results from an extended ctDNA analysis of paired PALOMA-3 plasma samples using hybridization capture-based, next-generation sequencing (NGS) assay covering 87 breast cancer, HR signaling, and cell cycle-related genes. Methods: Pre-/post-menopausal pts whose disease progressed after prior ET (N=521) were randomized 2:1 to receive F 500 mg + P (125 mg/d, 3 wk on/1 wk off) or placebo. Cell-free DNA extracted from paired plasma samples (n=194) was analyzed with a custom 87-gene NGS assay, to identify single nucleotide variants and copy number amplification (CNA), with molecular barcoding, high NGS coverage (10,000-20,000 reads per nucleotide position), and background error correction. Differences in ctDNA mut frequencies detected in P+F compared to F alone were assessed and their association to clinical outcome estimated. Results: Blinded assay qualification and droplet digital PCR validation suggested a mut detection frequency cutoff at 0.3%. A high coefficient of correlation with previously presented data was observed for ESR1 and PIK3CA variants (r=0.94 and 0.97, respectively), with acquisition of PIK3CA and ESR1 mutations at EoT in P+F and F groups. Gene level mut analysis of EoT plasma revealed no significant difference between P+F vs F alone (Table), although there was an increase in RB1 mutations in P+F consistent with previous data. Other acquired muts at EoT (SMAD4, NOTCH2, and CDKN1B) were observed at low frequencies. Muts in CDK4 and CDK6 were rarely observed (< 1% of pts), regardless of treatment arm. Detected Variants, Frequency, n (%) P+FF GenePre-TEoTPre-TEoTPre-T pvalEoT pvalPIK3CA47(37)51(40)19(28)22(33)0.2660.352ESR136(28)45(35)19(28)24(36)11TP5330(24)33(26)23(34)25(37)0.1280.137RB12(2)9(7)2(3)2(3)NA0.336PTEN5(4)7(6)3(4)3(4)11AKT17(6)7(6)2(3)2(3)0.7210.721 Conclusions: Our results corroborate the previously reported results demonstrating that genomic profiles of treatment resistant cancer are similar between P + F and F therapy. Expanded analysis of cell-cycle genes identified no new recurrently mutated genes, and confirmed that RB1 mutations are selected at low frequency after P+F treatment. Alterations in cell cycle genes may not be a common mechanism of resistance to CDK4/6 inhibitors in HR+ HER2- advanced breast cancer. Sponsor: Pfizer Citation Format: O'Leary B, Lira ME, Huang S, Deng S, Xie T, Kinong JK, Hardwick J, Rejto P, Liu Y, Huang X, Huang Bartlett C, André F, Loibl S, DeMichele A, Cristofanilli M, Turner NC. Longitudinal ctDNA sequencing using an expanded genomic panel in the PALOMA3 trial of palbociclib plus fulvestrant [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr PD2-02.