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Purpose: In KATHERINE, adjuvant T-DM1 reduced risk of disease recurrence or death by 50% compared with trastuzumab in patients with residual invasive breast cancer after neoadjuvant therapy (NAT) comprised of HER2-targeted therapy and chemotherapy. This analysis aimed to identify biomarkers of response and differences in biomarker expression before and after NAT. Experimental Design: Exploratory analyses investigated the relationship between invasive disease-free survival (IDFS) and HER2 protein expression/gene amplification, PIK3CA hotspot mutations, and gene expression of HER2, PD-L1, CD8, predefined immune signatures, and Prediction Analysis of Microarray 50 intrinsic molecular subtypes, classified by Absolute Intrinsic Molecular Subtyping. HER2 expression on paired pre- and post-NAT samples was examined. Results: T-DM1 appeared to improve IDFS versus trastuzumab across most biomarker subgroups, except the HER2 focal expression subgroup. High versus low HER2 gene expression in residual disease was associated with worse outcomes with trastuzumab [HR, 2.02; 95% confidence interval (CI), 1.32–3.11], but IDFS with T-DM1 was independent of HER2 expression level (HR, 1.01; 95% CI, 0.56–1.83). Low PD-L1 gene expression in residual disease was associated with worse outcomes with trastuzumab (HR, 0.66; 95% CI, 0.44–1.00), but not T-DM1 (HR, 1.05; 95% CI, 0.59–1.87). PIK3CA mutations were not prognostic. Increased variability in HER2 expression was observed in post-NAT versus paired pre-NAT samples. Conclusions: T-DM1 appears to overcome HER2 resistance. T-DM1 benefit does not appear dependent on immune activation, but these results do not rule out an influence of the tumor immune microenvironment on the degree of response.

PURPOSE: There is a lack of level I evidence to guide radiotherapy recommendations for patients receiving neoadjuvant chemotherapy for breast cancer. We utilized four neoadjuvant chemotherapy trials to determine which patients benefit from regional nodal irradiation (RNI). MATERIALS AND METHODS: We obtained data from NSABP B-18, B-27, B-40, and B-41 clinical trials. B-40 and B-41 allowed RNI at physician’s discretion. We evaluated local-regional recurrence (LRR), distant recurrence (DR), disease-free survival (DFS), and overall survival (OS). Kaplan-Meier, Peto-Peto, Chi-squared, Fisher exact, and Wilcoxon rank-sum tests were used for survival estimates and comparison. RESULTS: Median follow-up for B-18, B-27, B-40, and B-41 was 13.7, 9.7, 4.5, and 5.1 years, respectively, including 742, 2254, 1154, and 504 patients for analysis. On multivariable analysis, factors significantly associated with RNI included tumor size, ypN status, and tumor subtype; Hispanic patients were less likely to receive RNI. Patients with ypN+HER2+ disease who received RNI had improved OS. B-40 patients with ypN+HR+ disease had improved LRR. On multivariable analysis for the B-40 and B-41 study population, RNI was not associated with significantly improved OS, DFS, DR, or LRR. CONCLUSION: RNI was associated with a clinical benefit for patients with ypN+HER2+ and ypN+HR+ disease. RNI was not significantly associated with a clinically beneficial outcome for the entire cohort. Prospective phase III clinical trials are needed to establish guidelines for patients who should receive RNI following neoadjuvant treatment, and action is necessary to eliminate the disparity in care delivery shown for Hispanic women.

BackgroundThe cardiotoxic effects of doxorubicin, trastuzumab, and other anticancer agents are well known, but molecular genetic testing is lacking for the early identification of patients at risk for therapy-related cardiac toxicity.MethodsUsing the Agena Bioscience MassARRAY system, we genotyped TRPC6 rs77679196, BRINP1 rs62568637, LDB2 rs55756123, RAB22A rs707557, intergenic rs4305714, LINC01060 rs7698718, and CBR3 rs1056892 (V244M) (previously associated with either doxorubicin or trastuzumab-related cardiotoxicity in the NCCTG N9831 trial of anthracycline-based chemotherapy ± trastuzumab) in 993 patients with HER2+ early breast cancer from the NSABP B-31 trial of adjuvant anthracycline-based chemotherapy ± trastuzumab. Association analyses were performed with outcomes of congestive heart failure (N = 29) and maximum decline in left ventricular ejection fraction (LVEF) using logistic and linear regression models, respectively, under an additive model with age, baseline LVEF, and previous use of hypertensive medications as covariates.ResultsAssociations of maximum decline in LVEF in the NCCTG N9831 patients did not replicate in the NSABP B-31 patients. However, TRPC6 rs77679196 and CBR3 rs1056892 were significantly associated with congestive heart failure, p < 0.05, with stronger associations observed in patients treated with chemotherapy only (no trastuzumab) or in the combined analysis of all patients relative to those patients treated with chemotherapy + trastuzumab.ConclusionsTRPC6 rs77679196 and CBR3 rs1056892 (V244M) are associated with doxorubicin-induced cardiac events in both NCCTG N9831 and NSABP B-31. Other variants previously associated with trastuzumab-related decline in LVEF failed to replicate between these studies.

Background NSABP B-42 evaluated extended letrozole therapy (ELT) in postmenopausal breast cancer patients who were disease-free after 5 years of aromatase inhibitor-based (AI) therapy. Seven-year results demonstrated a non-statistically significant trend in disease-free survival (DFS) in favor of ELT. We present 10-year outcome results. Methods In this double-blind, phase 3 trial, patients with stage I-IIIA hormone receptor-positive breast cancer, disease-free after 5 years of an AI or tamoxifen followed by an AI, were randomized to 5 years of letrozole or placebo. Primary endpoint was DFS, defined as time from randomization to breast cancer recurrence, second primary malignancy, or death. All statistical tests are two-sided. Results Between 09/06 and 01/10, 3,966 patients were randomized (letrozole: 1,983; placebo: 1,983). Median follow-up time for 3,923 patients included in efficacy analyses was 10.3 years. There was statistically significant improvement in DFS in favor of letrozole compared to placebo (Hazard Ratio [HR]=0.85; 95%CI 0.74-0.96, p-value = 0.01, 10-year DFS: placebo = 72.6%, letrozole = 75.9%, absolute difference 3.3%). There was no difference in the effect of letrozole on overall survival (OS) (HR = 0.97, 95%CI 0.82-1.15, p-value = 0.74). Letrozole significantly reduced breast cancer-free interval (BCFI) events (HR = 0.75, 95%CI 0.62-0.91, p-value = 0.003, absolute difference in cumulative incidence: 2.7%) and distant recurrences (DR) (HR = 0.72, 95%CI 0.55-0.92, p-value = 0.01, absolute difference: 1.8%). The rates of osteoporotic fractures and arterial thrombotic events did not differ between treatment groups. Conclusions The beneficial effect of ELT on DFS persisted at 10 years. Letrozole also significantly improved BCFI and DR without improving OS. Careful assessment of potential risks and benefits is necessary for selecting appropriate candidates for ELT. Clinical Trials registration NCT00382070

Roughly 50% of newly diagnosed breast cancer is stage 1, the majority being ER/PR positive, HER2- negative. Genomic assays such as Oncotype DX® have identified patients with reduced distant metastasis and lack of chemotherapy benefit, allowing patients to avoid excess toxicity. These genomic assays have been shown to be prognostic for local-regional recurrence (LRR). The de-escalation of therapy is of interest to patients, providers, and payers. Low risk, as identified by both the use of Oncotype and Mammaprint® is associated with low LRR after lumpectomy and breast radiotherapy. TRIAL DESIGN: In the DEBRA trial, we hypothesized that breast-conserving surgery (BCS) alone is non-inferior to BCS plus radiotherapy for in-breast cancer control and breast preservation in women intending appropriate endocrine therapy for stage 1 (ER and/or PR-positive, HER2-negative, and Oncotype DX Recurrence Score [RS] low) breast cancer. Stratification is by age (1-2 cm), and RS 18, making them ineligible for the study. An extra step in the accrual process will require us to register 1,714 patients to ensure our final randomized cohort is 1,670 patients. Accrual: Screen 1,714 to randomize 1,670 into the study. Contact information: Protocol: CTSU member website: https://www.ctsu.org. NRG Oncology Pgh Clinical Coordinating Dpt: 1-800-477-7227 or ccd@nsabp.org. Support: U10CA180868, U10CA180822. NCT04852887. Citation Format: Julia White, Stewart J Anderson, Eleanor ER Harris, Eleftherios P Mamounas, Daniel G Stover, Patricia A Ganz, Reshma Jagsi, Reena S Cecchini, Carmen Bergom, Valerie Theberge, Mahmoud El-Tamer, Rich C Zellars, Dean A Shumway, Guang-Pei Chen, Thomas B Julian, Norman Wolmark. Evaluating de-escalation of breast radiation (DEBRA) following lumpectomy for breast conservative treatment of stage 1, hr+, HER2-, RS ≤18 breast cancer: NRG-BR007 a phase III trial [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 P3-18-04.

Over the last decade, rates of risk-reducing prophylactic mastectomy (PM) have risen dramatically. A topic of debate regarding the procedure is whether to use sentinel lymph node biopsy (SLNB) at the time of PM and what factors might predict for such need. In order to assess the rate of identifying presence of occult invasive breast cancer in the PM specimen, we performed a retrospective review of the pathology findings from a single-surgeon case-series of PM.Patients undergoing PM between January 2013 and June 2019 at Orlando Health Cancer Institute were identified for a retrospective chart review. Demographic, clinical, and histopathological data from the surgical procedure were collected and analyzed for the incidence of occult invasive breast cancer in the PM specimen.A total of 146 consecutive patients with PM were identified; 120 (82.2%) underwent contralateral PM (CPM) and 26 (17.8%) underwent bilateral PM (BPM). Final pathology of the 172 PM specimens identified 4 (3.3%) with lobular carcinoma in situ, 3 (2.5%) with atypical ductal hyperplasia, and 2 (1.7%) with atypical lobular hyperplasia and 2 (1.7%) with intraductal papilloma. No invasive malignancy was detected in any of the 172 PM specimens.The absence of occult invasive carcinoma in 172 consecutive PM specimens suggests a limited clinical utility in routinely performing SLNB in this setting. This study also suggests that use of preoperative breast MRI imaging could offer a potential non-invasive tool to detect occult malignancy and select patients who can safely undergo omission of SLNB at the time of PM.

Background: Pertuzumab, a monoclonal antibody targeting subdomain II of HER2 and blocking dimerization, was approved by the FDA in 2013 as neoadjuvant therapy in combination with trastuzumab + chemotherapy for HER2+ locally advanced or early-stage breast cancer patients (pts). TCHP (Docetaxel/Carboplatin/Trastuzumab/Pertuzumab) is a popular, non-anthracycline neoadjuvant therapy. In the TRYPHAENA trial, pathologic complete response (pCR) rate was 63.6% with 6 cycles of neoadjuvant TCHP (47.5% in ER+/PR+ and 81.1% in ER-/PR- tumors). We previously reported (SABCS 2015) our institutional experience with neoadjuvant TCHP in 75 pts with operable/locally advanced HER2+ breast cancer (10/2013 - 12/2015). Now we report our updated experience of 230 pts (10/2013 - 12/2019) with neoadjuvant chemotherapy + dual anti-HER2 therapy. Patients & Methods: Medical record search identified HER2+ pts (T1c-T3/N0-3 or Tany/N1-3) treated with neoadjuvant chemotherapy + dual anti-HER2 therapy from 10/2013 to 12/2019. Collected information included pt and tumor characteristics at diagnosis, details of neoadjuvant therapy, clinical, radiologic, & pathologic assessment of tumor response, type of breast and axillary nodal surgery, and long-term disease outcomes. Results: 230 pts (229 female, 1 male) met the inclusion criteria; median age: 52 yrs (range 25-79); Clinical stage: I (2%), II (78%) , III (20%); ER+ and/or PR+ 70% ; ER-/PR- 30%. 228 pts received TCHP and 2 pts AC then THP. 170 pts (74%) received 6 cycles of TCHP without dose reduction; 49 pts (21%) received 6 cycles, but with dose reduction (most commonly due to diarrhea, nausea, neutropenia, and anemia); 11 pts (5%) received < 6 cycles (7 of those also needed dose reduction). Mean left ventricular ejection fraction was 62.0% pre-treatment, and 60.9% post-treatment. Of the 230 pts who underwent breast surgery (1 had no breast primary at presentation), 86 pts (38%) had breast conserving surgery, 19 (8%) unilateral mastectomy, and 124 (54%) bilateral mastectomy. Axillary assessment was by SLNB in 75% and ALND in 25% (with/without SLNB). Among 138 pts with cN0 and axillary assessment, 124 had SLNB (4 had + nodes), 14 had ALND (11 had + nodes). Among 91 pts with cN1-3, 47 had SLNB (1 had + nodes) and 44 had ALND (27 had + nodes). Overall pCR rate (ypT0/Tis, ypN0) was 59%. pCR rate was 50% for ER+ and/or PR+, and 79% for ER-/PR-. pCR by Stage: I (50%), II (60%), III (55%). At median follow-up of 2.9 years, 221 pts (96%) were alive with no evidence of disease; 8 pts (3.5%) have experienced recurrence (6 distant, 1 locoregional, 1 unknown site), and 1 pt died after developing AML as the only event. The table below presents details on the 8 pts who suffered recurrence: 4 had clinical stage II disease, and 4 clinical stage III. All pts had hormone receptor + tumors at diagnosis. 7 of 8 pts (88%) with recurrence did not have pCR at surgery. Most common sites of distant metastases as first event were liver and bone. Of the 8 pts with recurrence, 6 are alive with disease (median follow-up 2.8 years). There was 1 death due to disease progression, and 1 pt was lost to follow-up. Conclusions: Our updated results continue to demonstrate the clinical safety and efficacy of neoadjuvant therapy with TCHP for operable/locally advanced HER2+ breast cancer. Our pCR rates are similar to those observed in the TRYPHAENA trial. Longer follow-up is required to evaluate the long-term clinical outcomes with this regimen. Recurrence DataPatient NumberAge at DiagnosisDate of DiagnosisHormone Receptor at DiagnosisClinical Stage at DiagnosisType of Breast SurgerypCRPathologic Stage at SurgeryDate of RecurrenceTime to Metastases (Years)Site of Recurrence16511/19/14PositivecT2N1 (IIB)Left MastectomyYesypT0N0 (0)4/6/172.4Liver, Bone2366/15/15PositivecT2N0 (IIA)Bilateral MastectomyNoypT3N0 (IIB)3/19/182.8Liver3546/29/15PositivecT2N3 (IIIC)Left MastectomyNoypT1bN1a (IIA)10/2/194.3Bone4577/1/15PositivecT2N3 (IIIC)Left LumpectomyNoypT1cN1a (IIA)2/4/193.6Bone, Soft Tissue5568/20/15PositivecT2N0 (IIA)Left LumpectomyNoypT1aN0 (IA)6/28/182.8Lymph Node6264/29/16PositivecT4N0 (IIIB)Bilateral MastectomyNoypT2N1 (IIB)12/13/171.6Liver7539/27/16PositivecT3N3 (IIIC)Bilateral MastectomyNoypT3N3 (IIIC)Not KnownNot KnownNot Known8319/3/17PositivecT2N1 (IIB)Bilateral MastectomyNo (clinical progression)ypT3N2a (IIIC)6/25/180.8Lungs Citation Format: Nirja Shah, Nikita Shah, Said Baidas, Ana Cuesta-Fernandez, Marc Demers, Maria Demori, Tomas Dvorak, Rachel Eisenberg, Terrence Gross, Danielle Henry, Michael Kahky, Patrick Kelly, Swathy Kolli, Regan Rostorfer, Jeffrey Smith, Cameron Swanick, Eleftherios Mamounas. Clinical outcomes with neoadjuvant chemotherapy plus dual anti-HER2 therapy in patients with operable/locally advanced breast cancer: Single institution experience [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS10-42.

Expression of human epidermal growth factor receptor 2 (HER2) in breast cancer defines a subset of patients (∼15%-20%) who are candidates for anti-HER2 therapies, most notably, trastuzumab, pertuzumab, antibody drug conjugates (eg, T-DM1), and tyrosine kinase inhibitor (TKI) drugs (eg, lapatinib and neratinib), all of which have dramatically changed the prognosis for this aggressive subtype of breast cancer. A roundtable meeting of the Breast Cancer Therapy Expert Group (BCTEG) was convened in March 2018 in an effort to discuss and clarify, from the perspective of the practicing community oncologist, recent developments in the diagnosis and treatment of HER2-positive (HER2+) breast cancer. Members of the group selected 4 key topics for discussion prior to the meeting, including diagnosis of HER2+ disease, and its treatment in the neoadjuvant, adjuvant, and metastatic settings. Approved testing methods, such as immunohistochemistry and fluorescence in situ hybridization, are used to demonstrate overexpression and/or amplification of HER2 in breast tumors, and established clinical guidelines are used to appropriately define treatment plans for patients with HER2+ disease. The panel acknowledges a range of treatment options now available for treatment of HER2+ breast cancer in the neoadjuvant, adjuvant, and advanced/metastatic settings, although it is noted that many controversies remain, including the optimal sequence of therapies, the most appropriate treatment(s) for subsets of patients with HER2+ disease (eg, hormone receptor-negative or -positive/HER2+), and uncertainties surrounding the diagnosis and definition of HER2+ disease. The current report summarizes the discussion of the BCTEG panel on this topic.

Background The phase 3 KATHERINE trial demonstrated significantly improved invasive disease–free survival with adjuvant trastuzumab emtansine (T‐DM1) versus trastuzumab in patients with HER2‐positive early breast cancer and residual invasive disease after neoadjuvant chemotherapy plus HER2‐targeted therapy. Methods Patients who received taxane‐ and trastuzumab‐containing neoadjuvant therapy (with/without anthracyclines) and had residual invasive disease (breast and/or axillary nodes) at surgery were randomly assigned to 14 cycles of adjuvant T‐DM1 (3.6 mg/kg intravenously every 3 weeks) or trastuzumab (6 mg/kg intravenously every 3 weeks). The European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire–Core 30 (QLQ‐C30) and breast cancer module (QLQ‐BR23) were completed at screening, at day 1 of cycles 5 and 11, within 30 days after study drug completion, and at 6‐ and 12‐month follow‐up visits. Results Of patients who were randomly assigned to T‐DM1 (n = 743) and trastuzumab (n = 743), 612 (82%) and 640 (86%), respectively, had valid baseline and ≥1 postbaseline assessments. No clinically meaningful changes (≥10 points) from baseline in mean QLQ‐C30 and QLQ‐BR23 scores occurred in either arm. More patients receiving T‐DM1 reported clinically meaningful deterioration at any assessment point in role functioning (49% vs 41%), appetite loss (38% vs 28%), constipation (47% vs 38%), fatigue (66% vs 60%), nausea/vomiting (39% vs 30%), and systemic therapy side effects (49% vs 36%). These differences were no longer apparent at the 6‐month follow‐up assessment, except for role functioning (23% vs 16%). Conclusion These data suggest that health‐related quality of life was generally maintained in both study arms over the course of treatment., Patient‐reported outcomes are reported from the randomized, phase 3 KATHERINE trial, which demonstrated significantly improved invasive disease–free survival with adjuvant T‐DM1 compared with trastuzumab in patients who had residual invasive disease following neoadjuvant chemotherapy plus HER2‐targeted therapy. Patients who are treated with T‐DM1 have a greater incidence of any grade and grade ≥3 adverse events compared with trastuzumab‐treated patients; however, these adverse events appear to have a minimal impact on patient‐reported quality of life.

Background: Patients with HER2-positive early breast cancer with residual invasive disease after neoadjuvant chemotherapy (NACT) + HER2-targeted therapy have a higher risk of recurrence and death than those with pathologic complete response. In the phase III KATHERINE study, adjuvant T-DM1 reduced the risk of recurrence or death by 50% vs H in this population. Data from KATHERINE subgroups are reported here, including patients treated with non-anthracycline (AC) vs AC based NACT, patients with small tumors (cT1cN0) who typically do not receive neoadjuvant treatment, and patients with particularly higher-risk tumors defined by nodal involvement and hormone-receptor status. Methods: Eligible patients had HER2-positive early breast cancer, received taxane- and H-containing neoadjuvant therapy ± AC followed by surgery, and had residual invasive disease in the breast and/or axillary nodes. Patients received 14 cycles of adjuvant T-DM1 (3.6 mg/kg IV q3w) or H (6 mg/kg IV q3w) and endocrine and/or radiation therapy per local standards. The primary endpoint was invasive disease-free survival (IDFS), defined as time from randomization to the first occurrence of ipsilateral locoregional or contralateral invasive breast cancer recurrence, distant recurrence, or death from any cause. In this exploratory analysis, efficacy subpopulations were derived from the intent-to-treat population and safety data were reported for patients who received ≥1 dose of study treatment. Results: In the non-AC v AC based NACT analysis (N=1486), some patient characteristics were imbalanced. For non-AC/AC based NACT, respectively, these included: region (North America; 60.6% v 11.0%), race (Asian; 12.8% v 7.4%), ECOG PS 1 (28.0% v 15.7%); neoadjuvant HER2-based therapy (H + pertuzumab; 46.6% v 9.8%), and neoadjuvant carboplatin/cisplatin (78.7 v 2.3%). Benefit was observed with T-DM1 regardless of neoadjuvant AC use (Table). The all-grade incidence of selected AEs with T-DM1 including hepatotoxicity, peripheral neuropathy, hemorrhage, IRR/hypersensitivity, and cardiac dysfunction was similar between non-AC and AC NACT groups. There was a small increase in the non-AC group in all-grade thrombocytopenia (32.5% v 27.4%) and pulmonary toxicity (6.7% vs 1.7%). There was an increased incidence of grade ≥3 AEs (39.9% vs 21.7%) in the non-AC vs the AC group with T-DM1 which was likely driven by an increase in thrombocytopenia (10.4% v 4.3%) and peripheral sensory neuropathy (4.3% vs 0.5%). However, the percentage of patients with AEs leading to T-DM1 withdrawal in the non-AC vs AC groups (19.6% v 17.5%) was similar, as was the percentage with AEs leading to T-DM1 dose reduction (14.1% v 11.6%). In patients with cT1N0 tumors (n=77), baseline characteristics were well-balanced for H v T-DM1. There were only 6 IDFS events in this subgroup overall; none were observed with T-DM1 (Table). In the analysis of particularly higher-risk tumors, all subgroups showed a benefit with T-DM1; the number of patients was small in some subgroups (Table). Conclusions: T-DM1 provides clinical benefit regardless of prior non-AC vs AC based NACT, and in subgroups with small or particularly higher-risk tumors. There was an increased incidence of grade ≥3 AEs with T-DM1 in the non-AC vs the AC group but these did not result in increased treatment discontinuation and were likely driven by the imbalance in prior therapy. Table 1. Risk of IDFS event in patients treated with non-AC versus AC based NACT, patients with small tumors, and patients with particularly higher-risk tumors.Unstratified hazard ratio of IDFS (95% confidence interval [CI])Patients treated with non-AC vs AC based NACT (N=1,486)Non-AC-based NACT: H (n=179) vs T-DM1 (n=164)0.43 (0.22–0.82)AC-based NACT: H (n=564) vs T-DM1 (n=579)0.51 (0.38–0.67)Patients with small (cT1cN0) tumors (N=77)H (n=32) vs T-DM1 (n=45)6 events with H; 0 events with T-DM1(hazard ratio not applicable due to zero events in T-DM1 arm)Tumor subgroups defined by nodal and HR status (N=957)Inoperable; any HR or ypN statusH (n=190)T-DM1 (n=185)3-year IDFS event-free rate, % (95% CI)60.2 (52.7–67.8)76.0 (70.0–82.4)Unstratified hazard ratio (95% CI)0.54 (0.37–0.80)Operable; ypN positive and HR negativeH (n=52)T-DM1 (n=58)3-year IDFS event-free rate, % (95% CI)69.5 (56.1–82.9)76.0 (64.5–87.5)Unstratified hazard ratio (95% CI)0.72 (0.35–1.50)Operable; ypN positive and HR positiveH (n=167)T-DM1 (n=168)3-year IDFS event-free rate, % (95% CI)77.2 (70.2–84.1)91.4 (86.6–96.2)Unstratified hazard ratio (95% CI)0.43 (0.25–0.75)Operable; ypN0 and HR negativeH (n=68)T-DM1 (n=69)3-year IDFS event-free rate, % (95% CI)77.2 (66.5–87.9)91.1 (84.3–97.9)Unstratified hazard ratio (95% CI)0.43 (0.17–1.06) Citation Format: Max S Mano, Sibylle Loibl, Eleftherios P. Mamounas, Gunter von Minckwitz, Chiun-Sheng Huang, Michael Untch, Norman Wolmark, Irene L. Wapnir, Youngsen Yang, Alison K. Conlin, Sherko Kümmel, Mahasti Saghatchian, Michael P. DiGiovanna, Claudia Strunk, Martina Zimovjanova, Chunyan Song, Haying Liu, David Tesarowski, Steven Blotner, Lisa H. Lam, Melanie Smitt, Charles E. Geyer Jr. Adjuvant trastuzumab emtansine (T-DM1) vs trastuzumab (H) in patients with residual invasive disease after neoadjuvant therapy for HER2-positive breast cancer: KATHERINE subgroup analysis [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P3-14-01.

Background The Adjuvant Zoledronic Acid (ZA) study in early breast cancer (AZURE) showed correlation between a non-amplified MAF gene in the primary tumor and benefit from adjuvant zoledronic acid (ZA). Adverse ZA outcomes occurred in MAF-amplified patients. NSABP B-34 is a validation study. Methods A retrospective analysis of MAF gene status in NSABP B-34 was performed. Eligible patients were randomly assigned to standard adjuvant systemic treatment plus 3-years oral clodronate (1600mg/daily) or placebo. Tumors were tested for MAF gene amplification, and analyzed for their relationship to clodronate for disease-free survival (DFS) and overall survival (OS) in MAF non-amplified patients. All statistical tests were 2-sided. Results . MAF status was assessed in 2,533 available primary tumor samples from 3,311 patients. Of these, 37 withdrew consent; in 77 samples no tumor was found; 536 assays did not meet quality standards, leaving 1,883 (77.8%) evaluable for MAF assay by fluorescence in situ hybridization (947 from placebo, and 936 from clodronate arms). At 5 years, in MAF non-amplified patients receiving clodronate, DFS improved by 30% (hazard ratio =0.70, 95% confidence interval = 0.51-0.94, P=0.02). OS improved at 5 years (hazard ratio =0.59, 95% confidence interval = 0.37–0.93, P=0.02) remaining statistically significant for clodronate throughout study follow-up. Conversely, adjuvant clodronate in women with MAF-amplified tumors was not associated with benefit, but possible harm in some subgroups. Association between MAF status and menopausal status was not seen. Conclusions Non-amplified MAF showed statistically significant benefits (DFS and OS) with oral clodronate, supporting validation of the AZURE study.

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, previous studies have found that women with residual disease have a substantially higher risk of recurrence than women with other subtypes of breast cancer. Additionally, other recent studies have found that therapeutic blockade of PD-L1 binding by atezolizumab has resulted in relevant anti-tumor efficacy. 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), nodal status (positive; negative), and PD-L1 status (positive; negative or indeterminate) 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. As of 7-8-19, 279/1,520 pts have been randomized. NCT03281954 Support: Genentech/Roche. Citation Format: Charles E Geyer Jr., Sibylle Loibl, Priya Rastogi, Sabine Seiler, Joseph P Costantino, Valentina Nekljudova, Patricia Cortazar, Peter C Lucas, Carsten Denkert, Eleftherios P Mamounas, Christian Jackish, Norman Wolmark. 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 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr OT2-04-08.

Purpose NSABP B-41, a phase three randomized trial, evaluated neoadjuvant lapatinib, trastuzumab, or the combination with chemotherapy in patients with HER2-positive operable breast cancer. Though no significant difference in pathologic complete response (pCR) was found among the three arms, pCR was associated with prolonged survival. We analyzed tumor intrinsic subtypes with Prediction Analysis of Microarray 50 in a subset of B-41 patients to determine their value in predicting HER2-targeting benefit. Methods Pearson’s Chi square test and logistic regression were used to compare pCR in the breast and nodes (ypT0/Tis ypN0). Kaplan–Meier estimates and Cox models were used to compare event-free and overall survival among subtypes. Results Intrinsic subtypes were determined in 271 baseline core biopsy samples. The pCR rate among patients with HER2-enriched (HER2E) subtype was greater compared to other subtypes combined (120/197, 60.9% versus 19/74, 25.7%; p

The increased use of neoadjuvant chemotherapy (NCT) has enabled higher rates of breast-conserving surgery (BCS) as well as provided prognostic information for women with breast cancer. High pathological complete response (pCR) rates question the requirement for surgery, with its attendant morbidity. In order to avoid surgery, the ability to predict pCR prior to it must be very high. Trimodality imaging alone is inadequate to predict pCR prior to surgery. We hypothesize that performing core-needle biopsy (bx) of the tumor bed in addition to trimodality imaging in patients (pts) having had a clinical complete response (cCR) will increase the ability to predict pCR. Utilizing predetermined imaging response criteria of complete or near-complete response coupled with a stereotactic core-needle bx of the tumor bed, BR005 aims to determine the predictive value of imaging followed by tumor bed bx for pCR and demonstrate its reproducibility across a multi-institutional setting. Methods: 175 pts with operable focal or multifocal (T1-T3), stage II/IIIA invasive ductal carcinoma (all receptor subtypes) will be entered. Pts must have completed a minimum of 8 wks of standard NCT and achieved a complete or near-complete radiologic tumor response on breast imaging with mammogram, ultrasound, and MRI, and undergo BCS. Following cCR and prior to surgery, pts will undergo a stereotactic-vacuum-assisted breast bx with clip placement. The primary endpoint is the proportion of pts with post-NCT neg image-directed bx who have a pCR. Residual cancer burden scores and core bx pathology will be collected along with trimodality imaging data. Evaluation after 135 pts will allow for the possibility of early termination of the study. Results will provide the first step toward a paradigm change in the treatment of breast cancer, enabling a study to assess the criteria for successful avoidance of surgery in pts with high response rates to NCT. Accrual as of 6-15-18: 39 (22.3%). Support: U10CA180868, -180822, UG1CA189867. Citation Format: Basik M, Costantino JP, De Los Santos JF, Umphrey HR, Julian TB, Mamounas EP, White JR, Lucas PC, Wagner JL, Tjoe JA, Thompson AM, Wolmark N. Phase II trial assessing accuracy of tumor bed biopsies in predicting pathologic response in patients with clinical/radiological complete response after neoadjuvant chemotherapy in order to explore the feasibility of breast-conserving surgery without surgery: NRG Oncology BR005 [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 OT1-09-01.

Introduction: The 21-gene Breast Recurrence Score® (RS) in the randomized NSABP B-20, SWOG S8814, and TAILORx studies predicted chemotherapy (CT) benefit for pts with N0 and N+ disease. Endocrine therapy was not inferior to chemoendocrine therapy in 6,711 randomized TAILORx pts with RS 11-25 and N0 disease. We characterized BCSM for the TAILORx-defined RS groups (0-10, 11-15, 16-20, 21-25, and 26-100) in the large population-based SEER study of pts treated based on RS results. Methods: RS results were provided electronically to SEER registries per their linkage methods (Petkov npj Breast Cancer 2016). Eligible pts were diagnosed Jan 2004 - Dec 2014 with N0 and N+(N1mic, 1-3 positive nodes[N1]), HR+, HER2-negative BC, and had no prior malignancy or multiple tumors, with follow-up information through Dec 2015. BCSM estimates by reported CT use yes vs. no/unknown were computed, and must be interpreted cautiously given lack of randomization. Results: There were 80,605 pts with RS results; 70,087 with N0 disease, 4,336 with N1mic, and 6,182 with N1. Median follow-up was 49 months, with 20,151 pts followed >76 months. 1,020 pts had experienced breast cancer death. There was a significant positive association between higher RS results and increased BCSM (p Table N0; CT Use No (N=55726)N0; CT Use Yes (N=14361)N1; CT Use No (N=3810)N1; CT Use Yes (N=2372)RS 0-10n139823891005283 9-y BCSM1.4% (1.0%, 2.1%)2.1% (0.7%, 5.9%)2.2% (1.0%, 4.8%)1.4% (0.4%, 4.6%)RS 11-15n1675810661193453 9-y BCSM2.0% (1.5%, 2.6%)2.7% (1.3%, 5.4%)1.5% (0.8%, 3.1%)4.4% (1.4%, 13.6%)RS 16-20n144842719992587 9-y BCSM2.2% (1.7%, 2.8%)1.9% (1.1%, 3.0%)3.8% (1.6%, 8.5%)4.2% (1.6%, 10.9%)RS 21-25n67043544397431 9-y BCSM3.9% (3.0%, 5.0%)3.4% (2.6%, 4.6%)7.1% (4.1%, 12.1%)5.7% (2.9%, 11.2%)RS 26-100n37986643223618 9-y BCSM8.8% (7.4%, 10.4%)7.0% (5.9%, 8.4%)15.2% (8.7%, 25.9%)10.8% (7.2%, 16.2%) Conclusion: In both N0 and N+ disease (up to 3 positive nodes), low RS results identify more than 70% of BC patients with excellent long-term outcomes and no apparent CT benefit, and high RS results (26-100) identifies an important minority of patients where CT reduces BCSM. Real-world evidence from SEER reconfirms that the 21-gene assay is prognostic and strongly suggests it is predictive of CT benefit, irrespective of nodal status. Citation Format: Hortobagyi GN, Shak S, Sledge, Jr. GW, Winer EP, Albain KS, Mamounas EP, Jakubowski DM, Petkov VI, Wolmark N. Breast cancer-specific mortality (BCSM) in patients (pts) with node-negative (N0) and node-positive (N+) breast cancer (BC) guided by the 21-gene assay: A SEER-genomic population-based study [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 P3-11-02.

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.

TPS613 Background: Approximately 50% of newly diagnosed breast cancers are stage 1, with the majority being ER/PR-positive, HER2-negative. Genomic assays such as the Oncotype DX® have identified patients (pts) with reduced risk of distant metastasis and without benefit from chemotherapy added to endocrine therapy, freeing them from excess toxicity. Genomic assays are also recognized as prognostic for in-breast recurrence (IBR) after BCS and could similarly allow de-escalation of adjuvant radiotherapy (RT). Reducing overtreatment is of interest to pts, providers, and payers. Methods: We hypothesize that BCS alone is non-inferior to BCS plus RT for in-breast recurrence and breast preservation in women intending endocrine therapy (ET) for stage 1 breast cancer (ER &/or PR positive, HER2-negative with an Oncotype DX Recurrence Score [RS] of ≤18). Stratification is by age (1-2cm), & (RS 18, making them ineligible for the study. In the accrual process, pts will be required to register (1,714 pts) to ensure that our final randomized cohort is 1,670 pts. Current accrual (2-2-2022) is 52 screened and 45 randomized. Support: U10CA180868, -180822, NCT04852887. Clinical trial information: NCT04852887.

1007 Background: Prospective and retrospective studies of patients (pts) with oligometastatic (OM) disease have supported that metastases (mets) directed treatment (MDT) with SBRT or SR in addition to standard of care systemic therapy (SOC ST) can improve progression-free (PFS) and overall survival (OS) compared with SOC ST alone. However, randomized evidence in oligometastatic breast cancer (OMBC) are lacking. NRG-BR002, a randomized Phase IIR/III trial, sought to determine the efficacy of SOC ST + MDT (SBRT or SR) as first line treatment of OMBC. Methods: OMBC pts with ≤ 4 extracranial mets on standard imaging with controlled primary disease were eligible if on first line SOC ST for ≤ 12 months without progression. Pts were randomized (1:1) to ARM 1 – SOC ST (mainly chemotherapy, endocrine therapy, anti-HER2) or ARM 2 – SOC ST with MDT of all mets. Stratification included mets number (1 vs > 1), ER/PR and Her2 status, and chemotherapy use. Phase IIR targeted sample size was 128 total/116 eligible pts, for 92% power and 1-sided significance level = 0.15 to determine if adding MDT shows a signal for improved PFS (hazard ratio [HR] = 0.55, corresponding to median PFS (mPFS) from 10.5 to 19 months), in order to continue to the full phase III trial for OS. PFS and OS were estimated by Kaplan-Meier and arms compared with log-rank. Results: 125 of the 129 pts randomized were eligible (ARM 1 = 65, ARM 2 = 60). Key characteristics included median age 54, 79% ER+ or PR+/HER2-, 13% HER2+, 8% triple negative. 60% had 1 metastasis and 20% presented synchronously with primary disease. Following randomization, systemic therapy was delivered to 95% in ARM 1 and 93% in ARM 2; ablation: SBRT 93%, SR 2%, and 5% none. The median follow-up was 30 mo. The mPFS (70% CI) in ARM 1 was 23 mo (18, 29) and 19.5 mo (17, 36) in ARM 2; 24 and 36-mo PFS (70% CI) for ARM 1 were 45.7% (38.9, 52.5) and 32.8% (26.0, 39.5) compared with 46.8 (39.2, 54.3) and 38.1 (29.7, 46.6) in ARM 2; HR (70% CI): 0.92 (0.71, 1.17); and 1-sided log-rank p = 0.36. As PFS did not show signal, OS reporting is included: median OS was not reached in either arm; 36-mo OS (95% CI) in ARM 1 71.8% (58.9, 84.7) and ARM 2 68.9% (55.1, 82.6; 2-sided log-rank p = 0.54). Analysis of first failure showed new mets outside index area (Arm 1) /RT field (Arm 2) developed similarly in both arms at 40%. There were fewer new mets inside treated/index area for Arm 2 6.7% vs ARM 1 29.2%, respectively. There were no grade 5 treatment-related adverse events (AEs), 1 grade 4 AE in ARM 1, and 9.7% and 5.3% grade 3 AEs in ARMS 1 and 2, respectively. Circulating tumor cell counts (0 vs ≥1) at baseline were similar in both arms and were not prognostic HR (95% CI): 1.04 (0.54, 2.02). Conclusions: The addition of MDT to SOC ST did not show signal for improved PFS, nor OS difference in patients with OMBC. The trial will not proceed to the Phase III component. Clinical trial information: NCT02364557.

PURPOSE Preclinical studies report that trastuzumab (T) can boost radiotherapy (RT) effectiveness. The primary aim of the B-43 trial was to assess the efficacy of RT alone vs concurrent RT plus T in preventing recurrence of ipsilateral breast cancer (IBTR) in women with ductal carcinoma in situ (DCIS). PATIENTS AND METHODS Eligibility: Eastern Cooperative Oncology Group (ECOG) performance status 0 or 1, DCIS resected by lumpectomy, known estrogen receptor (ER) and/or progesterone receptor (PgR), and human epidermal growth factor receptor 2 (HER2) status by centralized testing. Whole-breast RT was given concurrently with T. Stratification was by menopausal status, adjuvant endocrine therapy plan, and nuclear grade. Definitive intent-to-treat primary analysis was to be conducted when either 163 IBTR events occurred or all accrued patients were on study ≥ 5 years. RESULTS There were 2,014 participants who were randomly assigned. Median follow-up time as of December 31, 2019, was 79.2 months. At primary definitive analysis, 114 IBTR events occurred: RT arm, 63 and RT plus T arm, 51 (hazard ratio [HR], 0.81; 95% CI, 0.56 to 1.17; P value = .26). There were 34 who were invasive: RT arm, 18 and RT plus T arm, 20 (HR, 1.11; 95% CI, 0.59 to 2.10; P value = .71). Seventy-six were DCIS: RT arm, 45 and RT plus T arm, 31 (HR, 0.68; 95% CI, 0.43 to 1.08; P value = .11). Annual IBTR event rates were: RT arm, 0.99%/y and RT plus T arm, 0.79%/y. The study did not reach the 163 protocol-specified events, so the definitive analysis was triggered by all patients having been on study for ≥ 5 years. CONCLUSION Addition of T to RT did not achieve the objective of 36% reduction in IBTR rate but did achieve a modest but statistically nonsignificant reduction of 19%. Nonetheless, this trial had negative results. Further exploration of RT plus T is needed in HER2-positive DCIS before its routine delivery in patients with DCIS resected by lumpectomy.

PURPOSE: Accrual to clinical trials that challenge well-established treatment paradigms represents a unique challenge. Physician opinions on investigation of a novel approach to breast cancer treatment, in which patients with complete response to neoadjuvant chemotherapy are offered omission of lumpectomy, is unknown. NRG-CC006 sought to describe physician attitudes toward a novel approach to breast cancer treatment. METHODS: We recruited 18 participants in the fields of surgery, medical oncology, and radiation oncology to participate in semi-structured telephone interviews. Main outcomes are qualitative themes associated with omission of surgery. RESULTS: Of 18 interview participants, specialty and gender were evenly represented across surgery, medical oncology, and radiation oncology. Qualitative themes included general attitudes toward treatment de-escalation, stakeholder considerations, and trial/protocol considerations. The vast majority of participants expressed interest in investigation of omission of surgery, with all participants endorsing need for further investigation into treatment de-escalation. Stakeholder considerations in opening such a trial emphasized need for multidisciplinary involvement, and particularly, the unique role of surgeons as gatekeepers in breast cancer treatment. Finally, participants endorsed a need for further foundational studies to develop ways to predict complete pathologic response to chemotherapy without surgical intervention. CONCLUSIONS: Physicians expressed interest in investigating a novel approach to breast cancer treatment that would omit surgery in complete responders to neoadjuvant chemotherapy. Multidisciplinary input, and specifically surgeon engagement, will be key to the success of future investigations. Ongoing work to develop approaches to predict pathologic complete response accurately is needed to achieve the promise of this idea. CLINTRIALS #: BR005: NCT03188393 June 13, 2017

Our objective was to validate the NSABP 8-gene trastuzumab-benefit signature, developed and initially validated in NRG Oncology/NSABP B-31 in Alliance/NCCTG N9831. The B-31 and N9831 trials demonstrated the benefit of adding trastuzumab to chemotherapy in the adjuvant setting for HER2+ breast cancer patients. NSABP investigators utilized gene expression profiles of N9831 patients (N = 892) to blindly assign patients to large-, moderate-, or no-trastuzumab benefit groups and then NCCTG investigators assessed the degree of trastuzumab benefit using Cox models adjusted for age, nodes, estrogen receptor/progesterone receptor status, tumor size, and grade. Hazard ratios and 2-sided P values for recurrence-free survival of the predicted large- (n = 387), moderate- (n = 401), and no-benefit (n = 104) groups, based on the 8-gene signature were 0.47 (95% CI = 0.31 to 0.73, P < .001), 0.60 (95% CI = 0.39 to 0.92, P = .02), and 1.54 (95% CI = 0.59 to 4.02, P = .38), respectively (Pinteraction = .02), providing validation of the 8-gene signature in an independent study.

Triple-negative breast cancer (TNBC), defined as breast cancer lacking expression of estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2 (HER2), accounts for up to 20% of all breast cancer, and it occurs at a higher frequency in younger, African American, and Hispanic women. Compared to breast cancers that are hormone receptor and/or HER2 positive, TNBC has an aggressive clinical course and worse prognosis. Because TNBC is by definition unresponsive to endocrine therapy (eg, tamoxifen, aromatase inhibitors) and HER2-directed therapies (eg, trastuzumab), chemotherapy continues to play an important role. TNBC constitutes a molecularly heterogeneous group of tumors that can vary in response to treatment, and clinical management can be challenging, particularly for the practicing community oncologist, for whom breast cancer may be only one of many tumor types encountered. In January 2020, the Breast Cancer Therapy Expert Group (BCTEG) convened a roundtable discussion on the topic of advances in the treatment of TNBC. Topics discussed included histopathologic classification/definition of TNBC, neoadjuvant strategies, adjuvant chemotherapy (with special emphasis on management of patients who do not experience a pathologic complete response), and treatment of metastatic disease. Also reviewed was the wide range of emerging pathways and therapies currently under investigation to expand TNBC treatment options, including immunotherapies and poly(ADP-ribose) polymerase (PARP) inhibitors. This article summarizes the BCTEG discussion and highlights the key opinions relating to the treatment of patients with TNBC.

PURPOSE Adjuvant trastuzumab reduces invasive breast cancer (IBC) recurrence and risk for death in patients with HER2-amplified or overexpressing IBC. A subset of patients in the landmark trastuzumab adjuvant trials who originally tested HER2-positive but were HER2-negative by central HER2 testing appeared to possibly benefit from trastuzumab. The objective for the NSABP B-47 trial was to determine whether the addition of trastuzumab to adjuvant chemotherapy (CRx) would improve invasive disease-free survival (IDFS) in patients with HER2-negative breast cancer. PATIENTS AND METHODS A total of 3,270 women with high-risk primary IBC were randomly assigned to CRx with or without 1 year of trastuzumab. Eligibility criteria included immunohistochemistry (IHC) score 1+ or 2+ with fluorescence in situ hybridization ratio (FISH) < 2.0 or, if ratio was not performed, HER2 gene copy number < 4.0. CRx was either docetaxel plus cyclophosphamide or doxorubicin and cyclophosphamide followed by weekly paclitaxel for 12 weeks. RESULTS At a median follow-up of 46 months, the addition of trastuzumab to CRx did not improve IDFS (5-year IDFS: 89.8% with CRx plus trastuzumab [CRxT] v 89.2% with CRx alone; hazard ratio [HR], 0.98; 95% CI, 0.76 to 1.25; P = .85). These findings did not differ by level of HER2 IHC expression, lymph node involvement, or hormone-receptor status. For distant recurrence-free interval, 5-year estimates were 92.7% with CRxT compared with 93.6% for CRx alone (HR, 1.10; 95% CI, 0.81 to 1.50; P = .55) and for overall survival (OS) were 94.8% with CRxT and 96.3% in CRx alone (HR, 1.33; 95% CI, 0.90 to 1.95; P = .15). There were no unexpected toxicities from the addition of trastuzumab to CRx. CONCLUSION The addition of trastuzumab to CRx did not improve IDFS, distant recurrence-free interval, or OS in women with non-HER2–overexpressing IBC. Trastuzumab does not benefit women without IHC 3+ or FISH ratio-amplified breast cancer.

BACKGROUND: Several studies have reported a high risk of local disease recurrence (LR) and locoregional disease recurrence (LRR) in patients with breast cancer after neoadjuvant chemotherapy (NCT) ...

Background: There is increasing emphasis in providing high-value care. Value can be interpreted as a ratio of quality of care delivered and the cost to provide that care. We set out to evaluate the value of our care by defining a set of quality metrics (points) for each patient, then evaluating our cost to the payors to the deliver this care. Methods: Patients with clinical Stage IA breast cancer managed completely at our Cancer Center between 1/1/2014 and 12/31/2014 were identified from cancer registry. An IRB-approved retrospective review of clinical charts and financial data was performed. Based on The Advisory Board Company metrics, a set of 18 quality measures was developed. These included process measures (time to initial biopsy, rate of needle biopsy, time to pathology reports, ER/PR and HER2 assessment, pathology synoptic report generation, time to surgery or neoadjuvant chemotherapy), treatment measures (performance of sentinel node biopsy, administration of chemotherapy for ER- or HER2+ disease, administration of radiation for lumpectomy or pN2/pN3 disease after mastectomy, administration of endocrine therapy for ER+ disease), and complication measures (flap complication after reconstruction, chemotherapy ER visits and inpatient admissions). Depending on the treatment pathway, patients were eligible for a different number of quality points. A patient received a quality point if they were eligible for the measure and met it. Financial review identified actual technical revenue received by the hospital, and apportioned it accordingly to the various revenue centers. Revenue was included for 365 days after the date of first contact, and was used as a proxy for cost to the payors. All patients were included regardless of type of insurance or free-care. Results: There were 110 patients treated. All patients (100%) underwent surgery (lumpectomy 69%; mastectomy 5%, mastectomy with reconstruction 26%). Chemotherapy was delivered in 20% of patients (neoadjuvant 13%; adjuvant 7%). Radiation therapy was delivered in 57% of patients. Most common treatment pathways were lumpectomy with radiation (46%), mastectomy with reconstruction alone (18%), and lumpectomy alone (14%). Number of potential quality points depended on care pathway, and ranged from 6 to 15 per patient. There were 939 quality points achieved out of possible 1104 (85%) in the entire cohort. Quality ratios per patient varied from 55% to 100%. Lowest quality measure was time-to-surgery Conclusions: We have established a model to assess the value of breast cancer care provided as cost of care delivered per quality point achieved. To improve our value proposition to the payors, and ultimately to our patients, we plan to focus on improving our compliance with the quality measures, monitor care pathway utilization, and identify opportunities to lower the cost of care. Citation Format: Dvorak T, Rostorfer R, Smith J, Coltey D, Waters J, Mamounas E. Evaluation of quality, cost, and value in clinical stage IA 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 P4-12-10.

Background:Better tools are needed to estimate the risk of local recurrence (LR; DCIS or invasive) after breast-conserving surgery (BCS) for pts with DCIS in order to inform treatment decisions. Traditional clinico-pathologic (CP) factors, e.g., age and tumor size, provide an average LR risk derived from clinical trials and population studies. The Oncotype DX 12-gene DCIS Score assay has been validated to provide individual 10 yr LR risk estimates (Solin JNCI 2013; Rakovitch BCRT 2015). Previously we reported the impact of the DCIS Score result on radiotherapy (RT) recommendations including the pre-assay LR risk and RT recommendation and the change in RT recommendation from pre- to post-assay (Manders Ann Surg Oncol 2016).Recently a patient specific meta-analysis (MA) combined data from E5194 and Ontario DCIS Cohort (ODC) adjusting for pertinent clinico-pathologic factors to provide refined prediction estimates of LR risk after BCS alone (Rakovitch ASCO 2017). Herein we applied these risk estimates integrating DS, tumor size and patient age with adjustment for diagnosis in the year 2000 or later to refine estimates of LR in DCIS patients from the Manders et al study. Methods: 13 U.S. sites enrolled pts with DCIS treated with BCS alone from 3/2014 to 5/2015. Pts with LCIS but no DCIS, invasive BC, or planned mastectomy were excluded. Data were prospectively collected on CP factors, physician estimates of LR risk, and DCIS Score. Refined estimates of 10-yr risk of LR are presented by DCIS Score result category (0-38; 39-54; 55-100), age group (≥50 vs 1-2.5; >2.5 cm). Results: Of the 127 pts enrolled, median age was 60 yr,79.5% were postmenopausal. Median size was 8mm & 39% were ≤5mm. Median margin width was 3.0mm. ER and PR by IHC were positive in 89% and 78% of pts, respectively. For patients ≥50 yr with tumors ≤1 cm and low risk DS, the 10-yr LR risk ranges from 5.3-10.0%. A high DS result is associated with a higher 10-yr median predicted risk of LR in all subsets (table 1). The DCIS Score integrated with tumor size and patient age and the adjustment for diagnosis in 2000 or later provided risk estimates that are often lower than those provided by the DCIS Score alone without adjustment for diagnostic year. Using DS alone the percentage of patients with risk of LR Conclusions: Integration of the DCIS Score assay, that provides individual risk estimates of LR, with patient age and DCIS tumor size and adjusting for diagnosis in 2000 or later, provides refined estimates of 10-yr LR risk after BCS alone for DCIS. This integration enhances prognostic LR risk estimates and frequently provides lower risk estimates with which to guide individualized treatment decisions. Distribution of 10-year risk of local recurrence using DCIS Score (DS), tumor size, and age, adjusting for diagnosis in 2000 or later. Low DS (1-2.5≥50249.5 (7.3-12.6)914.2 (12.9-15.6)519.6 (16.5-20.4) < 50216.4 (16.1-16.7)220.4 (19.8-21.1)122.2 (22.2-22.2)>2.5≥50515.7 (14.9-23.7)0 138.4 (38.4-38.4) Citation Format: Manders JB, Solin LJ, Leonard CE, Mamounas EP, Lu R, Turner M, Baehner FL, White J. Refined estimates of local recurrence risk in a clinical utility study: Integrating the DCIS score, patient age and DCIS tumor size [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 P4-15-09.

This phase III post-NC trial evaluates if CWRNRT post-Mx or whole breast irradiation (WBI) with RNRT after BCS significantly reduces the IBCR-FI rate in pts with PPAx nodes that are pathologically negative after NC. Secondary aims are OS, LRR-FI, DR-FI, DFS-DCIS, second primary cancer, and comparison of RT effect on cosmesis in reconstructed Mx pts. Correlative science examines RT effect by tumor subtype, molecular outcome predictors for residual disease, and predictors for the degree of reduction in loco-regional recurrence. Methods: Clinical T1-3, N1 IBC PPAx nodes (FNA or core needle biopsy) pts complete ≥8 weeks of NC (anthracycline and/or taxane). HER2+ pts receive anti-HER2 therapy. Following NC, BCS or Mx, sentinel node biopsy (≥2 nodes) and/or Ax dissection with histologically negative nodes is performed. ER/PR and HER-2neu status before NC is required. Pts may receive appropriate adjuvant systemic therapy. Radiation credentialing with a facility questionnaire/case benchmark is required. Random assignment for Mx pts is to no CWRNRT or CWRNRT and for BCS pts to WBI or WBI+RNRT. Statistics: 1,636 pts are to be enrolled over 5 yrs (definitive analysis at 7.5 yrs). Study is powered at 80% to test that RT reduces the annual hazard rate of events for IBCR-FI by 35% for an absolute risk reduction of 4.6% (5-yr cumulative rate). Intent-to-treat analysis with 3 interim analyses (43, 86, and 129 events) and a 4th/final analysis at 172 events. Pt-reported outcomes focusing on RT effect will be provided by 736 pts before random assignment and at 3, 6, 12, and 24 mos. Accrual as of 6-21-18 is 967 (59.11%). Contacts: Protocol: CTSU member website https://www.ctsu.org. Questions: NRG Oncology Pgh Clin Coord Dpt: 1-800-477-7227 or ccd@nsabp.org. Pt entry: OPEN at https://open.ctsu.org or the OPEN tab on CTSU member website. NCT01872975 Support: U10 CA-2166; -180868, -180822; 189867; Elekta Citation Format: Mamounas EP, Bandos H, White JR, Julian TB, Khan AJ, Shaitelman SF, Torres MA, Vicini FA, Ganz PA, McCloskey SA, Paik S, Gupta N, Li XA, DiCostanzo DJ, Curran WJ, Wolmark N. Phase III trial to determine if chest wall and regional nodal radiotherapy (CWRNRT) post mastectomy (Mx) or the addition of RNRT to whole breast RT post breast-conserving surgery (BCS) reduces invasive breast cancer recurrence-free interval (IBCR-FI) in patients (pts) with pathologically positive axillary (PPAx) nodes who are ypN0 after neoadjuvant chemotherapy (NC): NRG Oncology/NSABP B-51/RTOG 1304 [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 OT2-04-01.

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: Lapatinib (L), a HER2 signaling, tyrosine kinase inhibitor, demonstrated numerically higher pCR in NSABP B-41 when added to paclitaxel (AC→P) and trastuzumab (T) following doxorubicin + cyclophosphamide (62% v 52.5%). We previously validated an 8-gene signature that predicted the degree of T benefit in NSABP B-31 and NCCTG9831. The purpose of this study is to determine the association of pCR with the 8- gene T-benefit groups, enabling the possibility of stratifying patients (pts) who do or do not receive benefit from L. Methods: Normalized B-41 nCounter® Breast Cancer 360 gene expression data was used to define the three T-benefit groups: large-, moderate-, and no-. The 8-gene signature was modified to use only 7 genes because one of the 8 genes was not included in the nCounter code set. The ability of the 7-gene signature to predict T benefit was equivalent to the 8-gene signature when tested in B-31. Comparisons within each treatment arm were made with Fisher's exact test. Results: The pCR rates were significantly different among the three groups in the AC→P+T arm: Large: 24/28 (86%); Moderate: 13/32 (41%); and No: 1/9 (11%); p Conclusions: The significant association of the modified 8-gene benefit groups with pCR in the AC→P+T arm suggests this signature could identify pts who may benefit from dual HER2-targeted neoadjuvant therapy. This could be tested in a meta-analysis including other neoadjuvant trials. Support: Lombardi CCC; BCRF; GSK; P30CA051008; Genentech; NSABP Table 1.pCR rates in trastuzumab benefit groups in NSABP B-41pCR rates in Breast and NodesTreatmentNo BenefitIntermediateLarge BenefitEntire Cohortp valueAC→P+T1/9 (11.1%)13/32(40.6%)24/28 (85.7%)38/69 (55.1%) Citation Format: Nan Song, Xiaoqing E. Tan, Ying Wang, Rim S. Kim, Hanna Bandos, Gong Tang, Eleftherios Mamounas, Charles E. Geyer, Priya Rastogi, Samuel A. Jacobs, Ashok Srinivasan, Peter C. Lucas, Soonmyung Paik, Norman Wolmark, Sandra M. Swain, Katherine L. Pogue-Geile. Association of pCR and the 8-gene signature: NRG Oncology/NSABP B-41 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 532.

502 Background: The 70-gene MammaPrint (MP) assay predicts risk of distant recurrence (DR) in hormone-receptor positive early-stage breast cancer and classifies cancers as Low Risk or High Risk. NSABP B-42 evaluated ELT in patients (pts) who had completed 5 yrs of adjuvant endocrine therapy (tx). The primary objective was to determine the utility of MP to identify pts enrolled in NSABP B-42 who are likely to benefit from ELT. Methods: A total of 1,866 pts from B-42 had available MP results. Primary endpoint is DR. Secondary endpoints are disease-free survival (DFS) and breast cancer-free interval (BCFI). For the primary analysis, pts were classified as High Risk (MP-H) (MP score ≤0.000) or Low Risk (MP-L) (MP score > 0.000). Exploratory analyses were performed for MP-L subcategories: MP Ultralow Risk (MP-UL) (MP score > 0.355) and MP-L but not MP-UL (MP-LNUL) (MP score > 0.000, ≤0.355). Likelihood ratio test based on stratified Cox proportional hazards (PH) model was used for treatment by risk group interaction. Stratified log-rank test was used to compare treatment groups. Hazard ratios and 95% CI were computed based on the stratified Cox PH model. Results: Among 1,866 pts, 706 (38%) were MP-H and 1,160 (62%) were MP-L. Of the MP-L, 252 (22%) were MP-UL. There were no significant differences in the distribution of patient and tumor characteristics between the MP group and the rest of the B-42 cohort, except for HER2 status. ELT effect was more pronounced in the MP cohort than in the overall B-42 population. For DR, there was statistically significant ELT benefit in MP-L (HR = 0.43, 95% CI 0.25-0.74, p = 0.002), but not MP-H (HR = 0.65, 0.34-1.24, p = 0.19) (interaction p = 0.38). For DFS, there was statistically significant ELT benefit in MP-L, but not MP-H (interaction p = 0.015). Similar findings were observed for BCFI (interaction p = 0.006). Within subcategories of MP-L, there was statistically significant ELT benefit in MP-LNUL, but not in MP-UL for all three endpoints, however the power in MP-UL was limited due to low number of pts (Table). Clinical trial information: 00382070. Conclusions: Statistically significant ELT benefit was observed for MP-L, but not MP-H. The treatment by risk group interaction was not statistically significant for DR, but it was for DFS and BCFI. The benefit appears to be stronger in MP-LNUL than in MP-UL. NCT: 00382070. Support: U10CA180868, -180822, U24CA196067; Novartis; Agendia.[Table: see text]

501 Background: The BCI HOXB13/IL17BR ratio (BCI-H/I) has been shown to predict endocrine tx (ET) and extended ET (EET) benefit. We examined the effect of BCI-H/I for EET benefit prediction in NSABP B-42, evaluating extended letrozole tx (ELT) in HR+ breast cancer patients (pts) who completed 5 yrs of ET. Methods: All pts with available primary tumor tissue were eligible. Primary endpoint was recurrence-free interval (RFI). Secondary endpoints were distant recurrence (DR), breast cancer-free interval (BCFI), and disease-free survival (DFS). Stratified Cox proportional hazards model was used. Due to a non-proportional effect of ELT on DR, time-dependent secondary analyses (≤4y, >4y) were performed. Likelihood ratio test evaluated treatment by BCI-H/I interaction. Results: In 2,179 pts analyzed (60% N0; 62% AI only; 80% HER2-), 45% were BCI-H/I-High and 55% BCI-H/I-Low. ELT showed an absolute 10y benefit of 1.6% for RFI (HR=0.77, 95% CI 0.57-1.05, p=0.10) (BCI-H/I-Low: 1.1% [HR=0.69, 0.43-1.11, p=0.13]; BCI-H/I-High: 2.4% [HR=0.83, 0.55-1.26, p=0.38]; interaction p=0.55). There was no statistically significant ELT by BCI-H/I interaction for BCFI (BCI-H/I-Low: HR=0.53, 0.36-0.78, p=0.001; BCI-H/I-High: HR=0.85, 0.60-1.21, p=0.36; interaction p=0.07) or for DFS (BCI-H/I-Low: HR=0.75, 0.58-0.95, p=0.017; BCI-H/I-High: HR=0.81, 0.64-1.04, p=0.09; interaction p=0.62). Before 4y, there was no statistically significant ELT benefit on DR in either BCI-H/I group. After 4y, BCI-H/I-High pts had statistically significant ELT benefit on DR (HR: 0.29, 0.12-0.69, p=0.003), while BCI-H/I-Low pts were less likely to benefit (HR: 0.68, 0.33-1.39, p=0.28) (interaction p=0.14). Conclusions: BCI-H/I prediction of ELT benefit on RFI was not confirmed. In time-dependent DR analyses, BCI-H/I-High pts had statistically significant benefit from ELT after 4y, while BCI-H/I-Low pts did not. Observed ELT benefit on BCFI in BCI-H/I-Low pts was primarily driven by second primary breast cancers. Additional follow-up is needed to further characterize BCI-H/I predictive ability in this study. Support: U10CA180868, -180822, U24CA196067; Novartis; Biotheranostics. Clinical trial information: NCT00382070. [Table: see text]

Background: Extending adjuvant endocrine therapy (tx) after 5 yrs of tamoxifen (Tam) with either Tam or an AI improves disease-free survival (DFS) in early-stage breast cancer (BC). However, optimal duration of adjuvant AI tx beyond 5 yrs is unknown. NSABP B-42 aimed to determine whether 5 yrs of letrozole (L) v placebo (P) improves DFS in patients (pts) who have completed 5 yrs of hormonal tx (with either AI or TAM→AI). Methods: Postmenopausal pts with stage I-III, hormone-receptor (+) BC, disease-free after 5 yrs of either AI or Tam for ≤3 years→AI for the remainder of 5 yrs, were randomized to L 2.5 mg or P daily for an additional 5 yrs. Stratification was by pathological nodal status, prior adjuvant Tam or not, and baseline dexa T scores (>-2.0, ≤-2.0 SD). Primary endpoint was DFS including local, regional, distant recurrence (DR), second primary cancers, and deaths from any cause as first event. Secondary endpoints included overall survival (OS), BC-free interval (BCFI including recurrence or contralateral BC as first event), DR, osteoporotic fractures (OF), and arterial thrombotic (AT) events. Differences in DFS, OS, BCFI, DR, OF, and AT between L and P were assessed by the stratified log-rank tests and Cox proportional hazards models. Statistical significance level for DFS was set at 0.0418 as per statistical plan. Results: From 9/06-1/10, 3966 pts were randomized (34% were Conclusions: After 5 yrs of an AI or TAM→AI, the beneficial effect of extended tx with 5 yrs of L on DFS did not reach statistical significance. There was no significant improvement in OS with L but L provided a significant improvement in BCFI and DR. Support: U10CA180868, -180822; UG1CA189867; Novartis. Citation Format: Mamounas EP, Bandos H, Lembersky BC, Geyer, Jr CE, Fehrenbacher L, Graham ML, Chia SL, Brufsky AM, Hennessy BT, Soori GS, Dakil SR, Seay TE, Wade, III JL, McCarron EC, Paik S, Swain SM, Wickerham DL, Wolmark N. A randomized, double-blinded, placebo-controlled clinical trial of extended adjuvant endocrine therapy (tx) with letrozole (L) in postmenopausal women with hormone-receptor (+) breast cancer (BC) who have completed previous adjuvant tx with an aromatase inhibitor (AI): Results from NRG Oncology/NSABP B-42 [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 S1-05.

Background: The use of molecular tools for prognosis and prediction of CT benefit in EBC has increased the complexity of decision making. The 21-gene RS (Oncotype DX) is included in the ASCO (2007) and NCCN guidelines (2006) for prognosis (risk of distant recurrence [DR]) and prediction of CT benefit in N0, ER+ EBC. In 2015, the NCCN added that the RS assay could be considered for select patients with 1-3 N+, ER+ EBC. Recently the ASCO BC biomarker/guideline group (J Clin Oncol 2016) advised that the “clinician should not use the 21-gene RS to guide decisions” and called the evidence quality “intermediate” and the recommendation “moderate” based on review of 2 N+ studies. It also advised no change in N+ clinical practice until the prospective SWOG S1007 study (RxPONDER) matures in several years. These discordant recommendations have led to major confusion among physicians, pts and payers. To address this controversy we herein report a comprehensive analysis of the body of evidence regarding the clinical utility of the RS in N+, ER+ EBC. Methods: All published studies involving N+, ER+ EBC with RS data were analyzed by type of study design and category of trial (validation, supportive, decision impact, cost-effectiveness, and prospective outcomes). Results: 30 studies provided clinical evidence supporting the value and utility of the RS in N+, ER+ pts. 7 studies employed a prospective-retrospective design or were prospective outcomes with clinical utility in >8000 N+ pts (Table). 23 additional studies assessed the impact of RS on CT decisions or cost-effectiveness. Study in N+/ER+Type of studyNEndpoints/resultsSWOG S8814 (Lancet Oncol 2010)Pro-retro36710-year DFS and BCSS: RS predicts risk of DFS event, BC death, and CT benefit (none to slightly worse if very low risk RS and 1-3 N+)TransATAC (JCO 2010)Pro-retro3069-year DR: RS predicts risk of DR in pts treated with ET without CTECOG E2197 (JCO 2008)Pro-retro2325-year DR: RS predicts DR risk in CT+ET treated ptsNSABP B-28 (ASCO-BCS 2012)Pro-retro106510-year DRFI: RS predicts DR risk in CT+ET treated ptsPACS-01 (ASCO 2014)Pro-retro5305-year DRFI/DFS: RS predicts DR risk in CT+ET treated ptsSEER (npj BC 2016)Prospective outcomes46915-year BCSM: RS predicts BCSM; pts with RS Conclusions: The 21-gene RS has now been studied in >10,000 N+, ER+ EBC pts across 30 studies worldwide, including 2 prospective outcomes studies in >5000 pts, confirming that the RS consistently identifies low risk 1-3 N+ pts in whom CT can effectively and safely be avoided. This evidence suggests that ER+ pts with few N+ and low RS should have a discussion of the pros and cons of adjuvant CT until the results of RxPONDER provide a definitive answer in several years. Citation Format: Mamounas E, Goldstein L, Penault-Llorca F, Roche H, Gluz O, Harbeck N, Nitz U, O'Shaughnessy J, Albain K. Chemotherapy (CT) decision in patients (pts) with node-positive (N+), ER+, early breast cancer (EBC) in the wake of new ASCO guideline – A different take on the evidence for the 21-gene recurrence score (RS) assay [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 P1-07-02.

Background: Preclinical evidence has shown that in xenograft models with estrogen receptor (ER)+/HER2+ breast cancer, signaling through the ER pathway can be enhanced in the presence of anti-HER2 treatment and lead to treatment resistance. Concurrent targeting of ER and HER2 has led to enhanced treatment efficacy and complete tumor disappearance. We hypothesized that targeting ER with endocrine therapy concurrently with chemotherapy plus dual HER2 inhibition will not be antagonistic and can overcome ER-mediated resistance and result in higher pCR as neoadjuvant treatment of ER+/HER2+ breast cancer. NRG Oncology/NSABP B-52 is a phase III, multicenter, randomized neoadjuvant therapy trial designed to determine whether the addition of estrogen deprivation to neoadjuvant therapy consisting of docetaxel, carboplatin, trastuzumab, and pertuzumab (TCHP+Est-Dep) yields a greater rate of pCR (breast and nodes) than TCHP alone. Methods: A total of 315 patients (pts) were randomly assigned between January 15, 2014 and March 17, 2016 to receive neoadjuvant therapy consisting of TCHP with or without estrogen deprivation therapy. Pts with locally advanced, hormone receptor-positive, HER2+ invasive breast cancer with no evidence of metastatic disease were eligible. Premenopausal women randomized to estrogen deprivation therapy received ovarian function suppression with goserelin (LHRH agonist) or equivalent plus an aromatase inhibitor (AI). Postmenopausal women received an AI. The determination of pCR (breast and nodes) was defined as the absence of any invasive component in the resected breast specimen and all resected lymph nodes following completion of neoadjuvant therapy. Following the intent-to-treat principle, the difference between the rates of pCR (breast and nodes) was tested using the binomial test for the difference between two proportions. The study was designed to have a statistical power of 80% to detect an increase in the pCR rate from 45% in the TCHP alone group to 60% in the TCHP+Est-Dep group. Results: The groups were balanced, with 57% clinically node positive and 50% premenopausal. Assessments for pCR were available from 308 of 315 randomized patients. The pCR (breast and nodes) for TCHP alone and TCHP+Est-Dep were 40.9% and 46.1%, respectively (p=0.36). The pCR (breast) were 44.2% and 47.4%, respectively (p=0.57). Grade 3/4 toxicities included diarrhea (23%, Conclusion: The addition of estrogen deprivation to neoadjuvant chemotherapy is not antagonistic. It improved pCR rates numerically, but the improvement was not statistically significant. The combination did not increase toxicity and may be a reasonable approach since all patients will receive endocrine therapy after neoadjuvant therapy. Correlative science studies including evaluation of residual cancer burden (RCB) and long-term outcomes will help define the role of estrogen deprivation in the treatment of HER2+ early breast cancer. Support: U10CA180868, -180822; UG1CA189867, Genentech. Citation Format: Rimawi MF, Cecchini RS, Rastogi P, Geyer, Jr CE, Fehrenbacher L, Stella PJ, Dayao Z, Rabinovitch R, Dyar SH, Flynn PJ, Baez-Diaz L, Paik S, Swain SM, Mamounas EP, Osborne CK, Wolmark N. A phase III trial evaluating pCR in patients with HR+, HER2-positive breast cancer treated with neoadjuvant docetaxel, carboplatin, trastuzumab, and pertuzumab (TCHP) +/- estrogen deprivation: NRG Oncology/NSABP B-52 [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 S3-06.

Background: Pertuzumab, a monoclonal antibody targeting subdomain II of HER2 and blocking dimerization , was approved by the FDA in 2013 for use in combination with trastuzumab and docetaxel as neoadjuvant therapy for pts with HER2+, locally advanced, inflammatory or early-stage breast cancer (>2cm and/or node-positive). This accelerated approval was based on results from the NeoSphere and the TRYPHAENA trials. In NeoSphere, pathologic complete response in the breast and nodes [pCR] was 39.3% after 4 cycles of neoadjuvant pertuzumab/trastuzumab/docetaxel. In TRYPHAENA, pCR was 63.6% among 76 patients treated with 6 cycles of neoadjuvant TCHP(47.5% in pts with ER+and/or PR+/HER2+ tumors and 81.1% in those with ER-/PR-/HER2+ tumors). Aside from TRYPHAENA, we have limited information on clinical outcomes, with neoadjuvant TCHP. Here we report our institutional experience at UF Health Cancer Center, Orlando (UFHCC) with Neoadjuvant TCHP in patients with operable or locally advanced breast cancer. Patients and Methods: After IRB approval, electronic medical record search was performed in order to identify HER2+ patients with tumors T2-T4/N0-3 or Tany/N1-3, treated with neoadjuvant TCHP between 10/13 and 5/16. Information from chart review included patient and tumor characteristics at the time of diagnosis , details of neoadjuvant chemotherapy plus anti-HER2 therapy, clinical, radiologic and pathologic assessment of tumor response to neoadjuvant TCHP, type of breast and axillary nodal surgery, surgical outcomes as well as disease outcomes. Results: 76 patients (75 female, 1 male) met the inclusion criteria; median age: 52 yrs; 83% of pts presented with clinical stage II and 17% with clinical stage III; 62% were ER+ and/or PR+ and 38% were ER-/PR-negative. 49 patients received all planned 6 cycles without dose reduction. The remaining 27 patients required dose reduction due to rash, diarrhea, nausea, vomiting, neuropathy or neutropenia; 5 patients requested dose reduction due to poor quality of life and fatigue; 2 patients required dose delay due to asymptomatic cardio-toxicity with ≥ 10% drop in EF. None had symptomatic CHF; 37% of patients underwent breast conserving surgery, 7% unilateral mastectomy and 55% bilateral mastectomy. Surgical lymph node assessment was performed after neoadjuvant chemotherapy and included sentinel lymph node biopsy (SLNB) in 74%, axillary dissection (ALND) in 8% or both in 18% of pts. Overall pCR rate (ypT0/is, ypN0) was 63.2%. pCR rate was 53.1% in pts with ER+ and/or PR+ tumors and 79.3% in those with ER-/PR- tumors. pCR by stage was 61% for Stage IIA, 65% for Stage IIB, 67% for Stage IIIA and 71% for Stage IIIC. Toxicity profile was consistent with what has been observed in the TRYPHAENA trial with fatigue, nausea, vomiting and neuropathy being the more commonly noted grade 3/4 toxicities. With median follow up of 18 months, all patients are disease-free with no documented recurrences observed. Conclusion: Our clinical experience with neoadjuvant TCHP confirms the efficacy and safety data from the TRYPHAENA trial in a single-institution, tertiary care center setting. Citation Format: Tariq R, Ajaz B, Shah N, Mamounas E, Moroose R. A single-institution clinical experience with neoadjuvant docetaxel/carboplatin/trastuzumab/pertuzumab (TCHP): A safety and efficacy analysis [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 P5-16-28.

Late disease recurrence (more than 5 years after initial diagnosis) represents a clinical challenge in the treatment and management of estrogen receptor-positive breast cancer (BC). An international workshop was convened in Toronto, Canada, in February 2018 to review the current understanding of late recurrence and to identify critical issues that require future study. The underlying biological causes of late recurrence are complex, with the processes governing cancer cell dormancy, including immunosurveillance, cell proliferation, angiogenesis, and cellular stemness, being integral to disease progression. These critical processes are described herein as well as their role in influencing risk of recurrence. Moreover, observational and interventional clinical trials are proposed, with a focus on methods to identify patients at risk of recurrence and possible strategies to combat this in patients with estrogen receptor-positive BC. Because the problem of late BC recurrence of great importance, recent advances in disease detection and patient monitoring should be incorporated into novel clinical trials to evaluate approaches to enhance patient management. Indeed, future research on these issues is planned and will offer new options for effective late recurrence treatment and prevention strategies.

We retrospectively assessed association of stromal tumor-infiltrating lymphocytes (sTILs) with clinical outcomes and molecular variables reportedly predictive of trastuzumab-benefit in National Surgical Adjuvant Breast and Bowel Project B-31 (N = 2130). sTILs were assessed in 1581 eligible B-31 cases utilizing all available hematoxylin and eosin slides. Mean concordance between main reviewer and six other pathologists was 90.8% in 100 cases. Cox regressions were used to calculate hazard ratios (HRs). In chemotherapy and trastuzumab added to chemotherapy arms, increases in sTILs, as a semicontinuous variable (combined arms HR = 0.42, 95% confidence interval = 0.27 to 0.64, two-sided P

Disease recurrence (locoregional, distant) exerts a significant clinical impact on the survival of estrogen receptor–positive breast cancer patients. Many of these recurrences occur late, more than 5 years after original diagnosis, and represent a major obstacle to the effective treatment of this disease. Indeed, methods to identify patients at risk of late recurrence and therapeutic strategies designed to avert or treat these recurrences are lacking. Therefore, an international workshop was convened in Toronto, Canada, in February 2018 to review the current understanding of late recurrence and to identify critical issues that require future study. In this article, the major issues surrounding late recurrence are defined and current approaches that may be applicable to this challenge are discussed. Specifically, diagnostic tests with potential utility in late-recurrence prediction are described as well as a variety of patient-related factors that may influence recurrence risk. Clinical and therapeutic approaches are also reviewed, with a focus on patient surveillance and the implementation of extended endocrine therapy in the context of late-recurrence prevention. Understanding and treating late recurrence in estrogen receptor–positive breast cancer is a major unmet clinical need. A concerted effort of basic and clinical research is required to confront late recurrence and improve disease management and patient survival.

Background: CALGB (Alliance) 40603 measured the effects of adding carboplatin (Cb) and/or bevacizumab (Bev) to standard neoadjuvant chemotherapy (weekly paclitaxel x 12 then doxorubicin/cyclophosphamide every 2 weeks x 4) on pathologic complete response (pCR) rates in stage II-III triple-negative breast cancer (TNBC). As previously reported (Sikov et al, JCO 2015), pCR breast (ypT0/is) and pCR breast/axilla (pCR Br/Ax) (ypT0/isN0) rates increased from 46% to 60% and 41% to 54%, respectively, with Cb and from 48% to 59% and 44% to 52%, respectively, with Bev. Secondary endpoints included event-free survival (EFS) and overall survival (OS). Methods: EFS is measured from study entry to ipsilateral invasive breast or locoregional recurrence, distant recurrence or death from any cause and OS from study entry to death from any cause in all patients (pts) who started study treatment. Pts without an event were censored as of their last clinical assessment. Hazard ratios (HR) were calculated for pts who achieved pCR vs. not and for pts assigned to receive drug (Cb or Bev) vs. not. All p-values are 2-sided. Results: 443 pts started study treatment. Median follow-up was 39 months (range 28-66). 110 EFS events and 77 deaths have been reported. At 3 yrs, overall EFS was 74.1% and OS 83.2%. Pts who achieved pCR breast had 3-yr EFS of 84.8% vs. 61.8% for those who did not. Table 1 shows the association between pCR and pCR or minimal residual invasive disease (Residual Cancer Burden Class I (RCB I), Symmans et al, JCO 2007) and outcomes; p-values for all comparisons Table 1 pCR BreastpCR Br/AxpCR Br/Ax or RCB IYes/No N (%)231 (52%)/212 (48%)207 (47%)/236 (53%)266 (60%)/177 (40%)EFS-HR0.33 (0.22-0.50)0.30 (0.19-0.46)0.29 (0.20-0.43)OS-HR0.28 (0.17-0.46)0.20 (0.11-0.36)0.21 (0.13-0.34) Pts assigned to Cb vs. not had 3-yr EFS 76.5% vs. 71.6% and OS 81.9% vs. 84.6%. Pts assigned to Bev vs. not had 3-yr EFS 75.5% vs. 72.9% and OS 85.5% vs. 80.9%. Table 2 shows HRs by assigned treatment: Table 2 CbBevN (Yes/No)225/218222/221EFS - HR0.84 (0.58-1.22) p=0.360.80 (0.55-1.17) p=0.25OS - HR1.15 (0.74-1.79) p=0.530.76 (0.49-1.19) p=0.23 Conclusions: Pts with TNBC who achieved pCR with study treatment had significantly better EFS and OS than pts who did not, consistent with findings from a published meta-analysis (Cortazar et al, Lancet 2014); the addition of RCB I did not weaken this association. Our study was not powered to assess the impact of Cb or Bev on these endpoints. While our findings are consistent with predictions from the meta-analysis as to the impact of raising the pCR rate on EFS (Berry-Hudis, JAMA Oncology 2015), the wide confidence intervals illustrate the challenge of conclusively demonstrating a correlation between pCR increment and EFS benefit, especially as the control pCR rate rises. While the addition of Bev has failed to improve long-term outcomes in TNBC in large randomized adjuvant trials, our results support ongoing and planned neoadjuvant and adjuvant studies designed to further assess the value of Cb-containing regimens in stage II-III TNBC. Support: U10s - CA180821, CA180882, CA180820, CA076001, CA025224, CA180868, CA180888. Citation Format: Sikov WM, Berry DA, Perou CM, Singh B, Cirrincione CT, Tolaney SM, Somlo G, Port ER, Qamar R, Sturtz K, Mamounas E, Golshan M, Bellon JR, Collyar D, Hahn OM, Carey LA, Hudis CA, Winer EP. Event-free and overall survival following neoadjuvant weekly paclitaxel and dose-dense AC +/- carboplatin and/or bevacizumab in triple-negative breast cancer: Outcomes from CALGB 40603 (Alliance). [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 S2-05.

Background: In the management of DCIS clinicians and patients (pts) must choose between the various options for breast conservation treatment based on an assessment of local recurrence (LR) risk. Traditional clinicopathologic (CP) factors such as age, size, grade, margin width or comedo necrosis, provide an average LR risk derived from clinical trials and population studies. The Oncotype DX® 12-gene assay for DCIS gives individual 10-yr LR risk estimates and has now been validated in two studies in a total of 893 pts. We report the 2nd study assessing the impact of the DCIS Score result on XRT recommendations. In addition, surveys assessing pt and physician confidence will provide insight into the overall clinical utility of the DCIS Score result. Baseline characteristics including the pre-assay LR risk and XRT recommendation are described here; final results on change in XRT recommendation from pre- to post-assay and distribution of the score across the CP factors will be presented. Methods: 13 U.S. sites enrolled pts with DCIS from 3/2014-5/2015. Pts with LCIS but no DCIS, invasive BC, or planned mastectomy were excluded. Data were prospectively collected on CP factors, physician estimates of LR risk, DCIS score, and pre/post XRT recommendation. Each pt had a surgeon and radiation oncologist complete study surveys. Pt surveys were also administered pre/post assay for decision conflict and the STAIT anxiety survey. The LR risk estimates and XRT recommendations were analyzed for all physicians as well as by specialty. Descriptive statistics summarized study variables. 95% Clopper-Pearson Exact CIs were calculated for percent change in XRT recommendation. McNemar's test was used to determine if the proportion of pts had a significant change in XRT recommendation post assay. Paired t-tests were used to compare physician estimates of recurrence risk pre/post assay. Results: Of the 121 pts enrolled, median age was 61y (34-83) and 80.2% were postmenopausal. Median size was 8mm and 40% were < 5mm; 22.3% were grade 1, 51.2% grade 2, and 26.4% grade 3. Comedo necrosis was noted in 55.4% and 19% had multiple foci. Median margin width was 3mm and 47.1% had margins 1-3mm. ER and PR by IHC were positive in 88.4% and 75.2% of pts. Among the 242 MD risk assessments, mean 10-yr LR risk was 14.8% (range 4-50%) for any LR; 14.2% for surgeons and 15.3% for radiation oncologists. The pre-assay XRT recommendation was 70.2%; 68.6% for surgeons and 71.9% for radiation oncologists. Conclusions: The role of new molecular tools such as the DCIS Score assay that provide individual risk estimates for LR on treatment decisions is evolving. The DCIS pts enrolled in the study reveal inclusion of baseline features like higher nuclear grade (26%), comedo necrosis (55%) and margin width of 1-3mm (47%) that have historically been associated with XRT use. This represents a continued broadening of the assay use from the predominantly lower risk DCIS cohort in the 1st validation study (E5194). The impact on XRT decisions is critical to establishing the clinical utility of the assay. The decision impact analysis, differences in use of the assay among surgeons and radiation oncologists and the impact on overall confidence with the treatment decision will be presented. Citation Format: Manders JB, Kuerer HM, Smith BD, McCluskey C, Farrar WB, Frazier TG, Li L, Leonard CE, Carter DL, Chawla S, Medeiros LE, Guenther JM, Castellini LE, Buchholz DJ, Mamounas EP, Wapnir IL, Horst KC, Chagpar A, Evans SB, Riker AI, Vali FS, Solin LJ, Jablon L, Recht A, Sharma R, Lu R, Sing AP, Hwang ES, White J. The 12-gene DCIS score assay: Impact on radiation treatment (XRT) recommendations and clinical utility. [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 P5-17-03.

Background: Increasing use of NCT regimens and improved selection of appropriate candidates has increased rates of pCR and has raised the question of whether surgical removal of the primary tumor is required for these patients (pts). To avoid surgery, the ability to predict pCR after NCT must be very accurate. Breast imaging alone (even when it includes mammogram, ultrasound, and breast MRI), is inadequate to achieve this. We hypothesized that performing core needle biopsy (bx) of the tumor bed in addition to tri-modality imaging in pts who have clinical complete response (cCR) to NCT will increase the ability to predict pCR. Methods: NRG-BR005 was planned as a two-stage Phase II trial, designed to assess the accuracy of post-NCT stereotactic tumor bed bx for pCR (absence of both invasive and DCIS residual disease), in pts with cCR and radiologic complete response (rCR)/near rCR by tri-modality imaging. Pts with operable (T1-T3, stage I/IIIA) invasive ductal carcinoma were eligible. Pts must have completed NCT and achieved a cCR as well as rCR/near rCR by mammography (mass ≤1 cm and no malignant microcalcifications), ultrasound (mass ≤2cm), and MRI (no mass with rapid rise or washout kinetics). Pts underwent marker-directed stereotactic multiple-core needle bx of the tumor bed with marker placement to facilitate BCS. The primary endpoint was the negative predictive value (NPV) of the bx, defined as the number of pts with a negative bx and confirmed pCR at BCS divided by the total number of pts with a negative bx. A bx detection NPV of >90% was required to support the feasibility of foregoing BCS. We also calculated the sensitivity of bx, defined as the number of pts with positive bx who had residual tumor at BCS divided by the total pts with residual tumor at BCS. The point estimate and 95% confidence intervals (CI) for these parameters were calculated using the exact method. Planned accrual was 175 pts in order to obtain 35 pts who had residual tumor at surgery. Results: From 8/17 to 6/19, 105 pts were accrued. As of 7/31/19, 98 pts were evaluable for analysis. Pts were 62.2% white, 87.7% non-Hispanic or Latino, 44.9% estrogen receptor-positive, and 44.9% HER2 positive. Among evaluable pts, 36 had residual disease at surgery. Stereotactic bx was positive in 18/36 pts (50%). Stereotactic bx was negative for all 62 pts who achieved pCR. NPV of the bx was 77.5% (95% CI: 66.8% to 86.1%) indicating that a negative bx provided incorrect diagnosis in 22.5% of pts. Sensitivity of the bx was 50% (95% CI: 32.9% to 67.1%) indicating that when disease was present, the bx detected it only 50% of the time. Complications from bx were reported in 7/98 evaluable pts (7.1%) (6 post-procedure hematomas, 1 breast pain). Conclusions: In the current findings of NRG-BR005, bx did not achieve an NPV of >90% and identified only 50% of the pts who had residual disease at surgery following NCT. The findings do not support breast-conserving treatment without surgery based on the study criteria for cCR and rCR/near rCR and negative tumor bed bx. Further analyses including central review of the tri-modality imaging and assessment of the imaging algorithm with and without the addition of bx are underway. Once these analyses are combined with information on biologic subtypes, a new prediction model may be defined. Support: U10CA180868, U10CA180822. Citation Format: Mark Basik, Reena S Cecchini, Jennifer F De Los Santos, Heidi R Umphrey, Thomas B Julian, Eleftherios P Mamounas, Julia White, Peter C Lucas, Christa Balanoff, Antoinette R Tan, Joseph J. Weber, David A Edmonson, Ursa A. Brown-Glaberman, Emilia J. Diego, Mediget Teshome, Cindy B Matsen, Samantha A Seaward, Irene L. Wapnir, Jamie L Wagner, Judy A Tjoe, Alastair M Thompson, Norman Wolmark. Primary analysis of NRG-BR005, a phase II trial assessing accuracy of tumor bed biopsies in predicting pathologic complete response (pCR) in patients with clinical/radiological complete response after neoadjuvant chemotherapy (NCT) to explore the feasibility of breast-conserving treatment without surgery [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr GS5-05.

Background: In the NSABP B-42 trial we aimed to determine whether 5 yrs of letrozole (L) v placebo (P) improves DFS in patients (pts) who have completed 5 yrs of hormonal therapy (tx). 3966 postmenopausal pts with stage I-III, hormone-receptor+ BC, disease-free after 5 yrs of an AI or tamoxifen (TAM) for ≤3 years → AI for the remainder of 5 yrs, were randomized to L 2.5 mg or P daily for an additional 5 yrs. In the primary analyses the beneficial effect of extended tx with 5 yrs of L did not reach statistical significance on disease-free survival (DFS). There was no significant improvement in overall survival (OS) with L, but L did provide a significant improvement in breast-cancer-free interval (BCFI) and distant recurrence (DR). The updated results based on the data received as of April 30, 2019, are presented here. Methods: Stratification was by pathological nodal status, prior adjuvant TAM or not, and baseline dexa T scores (>-2.0, ≤-2.0 SD). Primary endpoint was DFS including local, regional, distant recurrence, second primary cancers, and deaths from any cause as first event. Secondary endpoints included OS, BCFI (including recurrence or contralateral BC as first event), DR, osteoporotic fractures (OF), and arterial thrombotic (AT) events. Differences in DFS, OS, BCFI, DR, OF, and AT between L and P were assessed by the stratified log-rank tests and Cox proportional hazards models. Statistical significance level was set at 0.05. Results: Median follow-up for 3923 pts included in the current analyses was 9.3 yrs. As of 4/30/19, 890 DFS events had occurred (L=411, P=479); L resulted in a statistically significant increase in DFS v P (HR=0.84; 95% CI 0.74, 0.96; p=0.011); 10-yr DFS was L=76.1% and P=72.1%. The effect of L was statistically significantly different for pts with baseline T score ≤-2.0 (HR=0.63; 95% CI 0.49, 0.82) v those with a score >-2.0 (HR=0.93; 95% CI 0.80, 1.09) (interaction p=0.013). 495 deaths occurred (L=243, P=252); there was no statistically significant difference in OS with L v P (HR=0.97, 95% CI 0.82, 1.16; p=0.77); 10-yr OS was L=86.1% and P=85.5%. 413 BCFI events occurred (L=178, P=235); L v P resulted in a statistically significant 26% decrease in BCFI events (HR=0.74, 95% CI 0.61, 0.91; p=0.003); 10-yr cumulative incidence (Cum In) of BCFI was L=10.3% v P=13.3%. 229 DRs occurred (L=96, P=133); L v P resulted in a statistically significant 29% reduction in DR (HR=0.71, 95% CI 0.55, 0.93; p=0.01); 10-yr Cum In of DR was L=5.7% v P=7.5%. There were 209 OF (L=109, P=100). There were no significant differences in time to OF with L v P (P=0.46). Cum In of OF through 10 yrs was L=6.5% v P=6.4%. There were 154 AT events (L=82, P=72). Treatment with L did not result in an overall statistically significant increase in AT events compared to P (p=0.38). Cum In of AT through 10 yrs was L=4.7% v P=4.1%. Conclusions: The effect of extended tx with 5 yrs of L on DFS persisted in the updated analyses and reached statistical significance. There was no significant improvement in OS with L, but L continued to provide a significant improvement in BCFI and DR. Support: U10CA180868, -180822; UG1CA189867; Korea Health Technology R&D Project; Novartis. Citation Format: Eleftherios P Mamounas, Hanna Bandos, Barry C Lembersky, Jeon Hyeon Jeong, Charles E Geyer, Jr, Priya Rastogi, Louis Fehrenbacher, Mark L Graham, Stephen K Chia, Adam M Brufsky, Janice M Walshe, Gamini S Soori, Shaker R Dakhil, Thomas E Seay, James L Wade, III, Edward C McCarron, Soonmyung Paik, Sandra M Swain, D Lawerence Wickerham, Norman Wolmark. Ten-year results from NRG Oncology/NSABP B-42: A randomized, double-blinded, placebo-controlled clinical trial of extended adjuvant endocrine therapy with letrozole (L) in postmenopausal women with hormone-receptor+ breast cancer (BC) who have completed previous adjuvant therapy with an aromatase inhibitor (AI) [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr GS4-01.

Background Adjuvant systemic therapy reduces risk of distant recurrence (DR) and breast cancer death. In addition, adjuvant systemic therapy reduces risk of loco-regional recurrence (LRR). We examined the magnitude of the effect of adjuvant systemic therapy (tamoxifen, chemotherapy, and chemotherapy + trastuzumab) in reducing incidence rates and cumulative incidence rates of LRR as first event in nine recent NSABP randomized trials that were conducted from 1981 to 2005 and included a total of 21,815 patients. Methods Nine NSABP clinical trials of adjuvant (or neoadjuvant) systemic therapy, in which a reduction in LRR or DR was observed, were included in the analysis (NSABP B-13, B-14, B-19, B-20, B-21, B-27, B-28, B-30, and B-31). The cumulative incidence rates of LRR as the first disease-free survival (DFS) event were estimated and compared across treatment arms via log-rank tests. The sub-distribution proportional hazards models were applied to estimate the reduction in incidence rate of LRR from adjuvant systemic therapies. The corresponding magnitude of reduction in the incidence rate of any DFS event was estimated from Cox proportional hazards models. Results Across all nine clinical trials, adjuvant systemic therapy resulted in reductions in LRR that were comparable to or greater than the reductions in DFS events (Table). The observed reductions in LRR with adjuvant chemotherapy were of greater magnitude in trials of node-negative patients (35-58%) than in trials of node-positive patients (13-15%). Reductions in LRR were of similar magnitude with adjuvant chemotherapy as with adjuvant tamoxifen. In B-27, the sequential addition of neoadjuvant or adjuvant docetaxel to neoadjuvant AC reduced LRR rates by 27%. The addition of trastuzumab to adjuvant chemotherapy decreased LRR rates by 34%. Conclusions Rates of LRR have steadily declined over time in NSABP adjuvant clinical trials. This decline can be attributed to improvements in surgical and radiotherapy techniques but is also the result of the use of increasingly effective adjuvant systemic therapy. NSABP TrialPopulationTreatment ComparisonHR(95%CI)DFSHR(95%CI)LRR10-yr Cum Incidence of LRR(%)Log rank p-valueB-13 (n=1,084)N(-) / ER(-)MF v No Adj Rx0.66 (0.55,0.79)0.42 (0.29-0.62)5.9 v 13.5 Citation Format: Eleftherios P Mamounas, Gong Tang, Qing Liu, Jong-Heyon Jeong, Thomas B Julian, Priya Rastogi, Charles E Geyer, Sandra M Swain, Soonmyung Paik, D Lawrence Wickerham, Joseph P Costantino, Norman Wolmark. Effect of adjuvant systemic therapy in reducing rates of loco-regional recurrence in early-stage breast cancer: Results from nine NSABP randomized phase III trials [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P5-21-01.

Purpose Considerable molecular heterogeneity exists among human epidermal growth factor receptor 2 (HER2) –positive breast cancer regarding gene expression and mutation profiling. Evidence from preclinical, clinical neoadjuvant, and metastatic clinical trials suggested that PIK3CA mutational status and PAM50 intrinsic subtype of a tumor were markers of response to anti-HER2 therapies. We evaluated the predictive value of these two biomarkers in the adjuvant setting using archived tumor blocks from National Surgical Adjuvant Breast and Bowel Project (NSABP) trial B-31. Patients and Methods Expression data for 49 genes using the nCounter platform were used to generate PAM50 intrinsic subtypes for 1,578 archived tumor blocks from patients in the B-31 trial. Six PIK3CA hotspot mutations were examined by mass spectrometry of the primer extension products in a randomly selected subset (n = 671). We examined the heterogeneity of trastuzumab treatment effect across different subsets defined by each marker using Cox regression and disease-free survival as the end point. Results Seven hundred forty-one (47.0%) of 1,578 tumors were classified as HER2-enriched (HER2E) subtype, and 166 (24.7%) of 671 tumors had PIK3CA mutations. Hazard ratios (HRs) for trastuzumab in HER2E and other subtypes were 0.44 (95% CI, 0.34 to 0.58; P < .001) and 0.47 (95% CI, 0.35 to 0.62; P < .001), respectively (interaction P = .67). HRs for trastuzumab in PIK3CA wild-type and mutated tumors were 0.51 (95% CI, 0.37 to 0.71; P < .001) and 0.44 (95% CI, 0.24 to 0.82; P = .009), respectively (interaction P = .64). Conclusion Unlike results seen in the metastatic and neoadjuvant clinical trials, PIK3CA and PAM50 intrinsic subtypes were not predictive biomarkers for adjuvant trastuzumab in NSABP B-31. These data suggest that results from the metastatic and neoadjuvant setting may not be always applicable to the adjuvant setting.

Purpose Positive interim analysis findings from four large adjuvant trials evaluating trastuzumab in patients with early-stage human epidermal growth factor receptor 2 (HER2) –positive breast cancer were first reported in 2005. One of these reports, the joint analysis of North Central Cancer Treatment Group NCCTG N9831 (Combination Chemotherapy With or Without Trastuzumab in Treating Women With HER2-Overexpressing Breast Cancer) and the National Surgical Adjuvant Breast and Bowel Project NSABP B-31 (Doxorubicin and Cyclophosphamide Plus Paclitaxel With or Without Trastuzumab in Treating Women With Node-Positive Breast Cancer That Overexpresses HER2), was updated in 2011. We now report the planned definitive overall survival (OS) results from this joint analysis along with updates on the disease-free survival (DFS) end point. Methods In all, 4,046 patients with HER2-positive operable breast cancer were enrolled to receive doxorubicin and cyclophosphamide followed by paclitaxel with or without trastuzumab in both trials. The required number of events for the definitive statistical analysis for OS (710 events) was reached in September 2012. Updated analyses of overall DFS and related subgroups were also performed. Results Median time on study was 8.4 years. Adding trastuzumab to chemotherapy led to a 37% relative improvement in OS (hazard ratio [HR], 0.63; 95% CI, 0.54 to 0.73; P < .001) and an increase in 10-year OS rate from 75.2% to 84%. These results were accompanied by an improvement in DFS of 40% (HR, 0.60; 95% CI, 0.53 to 0.68; P < .001) and increase in 10-year DFS rate from 62.2% to 73.7%. All patient subgroups benefited from addition of this targeted anti-HER2 agent. Conclusion The addition of trastuzumab to paclitaxel after doxorubicin and cyclophosphamide in early-stage HER2-positive breast cancer results in a substantial and durable improvement in survival as a result of a sustained marked reduction in cancer recurrence.

Background: Abnormalities of the PI3kinase/AKT/mTOR signaling network are common in BC. This pathway is associated with resistance to endocrine therapies among HR+ tumors. Everolimus, an mTOR-inhibitor, increases the biological activity of endocrine therapy. S1207 evaluates the role of everolimus in combination with endocrine therapy in the adjuvant setting. Methods: Specific aims/ design: Randomized phase III double-blinded, placebo-controlled trial. Primary objective is to assess whether the addition of everolimus to standard adjuvant endocrine therapy improves invasive disease-free survival (DFS) among patients with high risk, HR+ BC. Secondary objectives include overall survival, distant recurrence-free survival, safety, adherence and QoL. Patients are randomized to receive standard adjuvant endocrine therapy in combination with one year of everolimus (10 mg PO daily) or placebo. Submission of tissue specimens/blood samples is required for translational studies Eligibility criteria: Patients with histologically confirmed HER2-negative and HR+ invasive BC treated with surgery, adjuvant chemotherapy and radiation therapy (if indicated) are eligible if they have: node-negative disease and tumors >2cm and a recurrence score (RS) >25; 1-3 positive nodes and RS >25 or grade 3 in the absence of RS; >4 positive lymph nodes regardless of RS. Patients >1 positive lymph node after completing neoadjuvant chemotherapy are eligible. Statistics/Target accrual:Parallel randomization design with equal allocation to the two treatment groups, the study will randomize 3,500 patients. All analyses are intent-to-treat with the primary analysis conducted 3 years after the last patient is randomized. The study has 90% power (with 2-sided α=0.05) to detect an effective hazard ratio of 0.75 for everolimus versus placebo, corresponding to a gain in DFS of approximately 4.3% at 5 years. All patients will be followed for 10 years. Support: NIH/NCI NCTN Grants CA180888, 180819, 180868, 180821,180822 189867, and in part by Novartis Clinical trial information: NCT01674140. Citation Format: Chavez-MacGregor M, Barlow WE, Pusztai L, Goetz MP, Rastogi P, Ganz PA, Mamounas EP, Paik S, Bandos H, Gralow J, Lew DL, Hortobagyi GN. Phase III randomized, placebo-controlled clinical trial evaluating the use of adjuvant endocrine therapy +/- one year of everolimus in patients with high-risk, hormone receptor (HR) positive and HER2-negative breast cancer (BC): SWOG/NRG/Alliance S1207 (NCT01674140). [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 OT1-03-11.