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Background: High-grade DCIS with immune infiltrates may represent lesions that are able to be kept in check by the immune system, but still are at risk for progression to invasive disease. We and others have demonstrated that the presence of T cells, and in particular the spatial proximity of CD8+/PD-1+ T cells and PD-L1+ cells predicts response to chemotherapy and PD-1 inhibitors in the setting of invasive triple negative breast cancer. DCIS with high-risk features (e.g. large, palpable, high grade, HR-, or HER2+) often have T cell infiltrates. We hypothesized that it might be possible to potentiate the immune response in high-risk DCIS with immune checkpoint blockade. Since mortality for DCIS is extremely low, we proposed an intralesional pembrolizumab (pembro) treatment approach to avoid systemic adverse effects. In a phase 1 dose escalation study of single agent pembro we found 2 doses of 8 mg, administered intralesionally 2-3 wks apart, was tolerable, induced immunological changes within the DCIS lesions, but had little clinical benefit. Herein, we expanded the number of injections to 4 and also tested a combination with mRNA-2752 (Moderna), an mRNA-based therapeutic encoding a T cell co-stimulator OX40L, and pro-inflammatory cytokines IL-23 and IL-36 gamma, to determine if we could find a dose that was both tolerable and elicited anti-tumor responses. Methods Women eligible for this study had DCIS with at least 2 of the following high-risk features: age< 45; high grade, extensive comedonecrosis; palpable mass; hormone receptor negative [HR-]; HER2+; size >5 cm, or microinvasion. A dose expansion cohort was performed using 4 doses of 8 mg pembro, 2-3 wks apart (n=5). We then combined pembro with mRNA-2752 (n=8 cases), initially at 8 and 4 mg, respectively. Dose reductions were implemented based on AEs. Patients received an MRI before and after 2 injections, spaced 2-3 wks apart. A total of 4 injections were allowed. Core biopsy or surgery was conducted after the last MRI. Results We observed an increase in T cell density in the dose expansion cohort (pembro only), except when there was a paucity of T cells in the pre-treatment biopsy. However, only 1 patient in this cohort demonstrated a reduction in lesion size (clinically and on MRI). As of 22SEP22, 8 patients have received the combination of pembro and mRNA-2752; 7 are evaluable. Two patients with minimal T cell infiltrates at baseline (both HR+) failed to respond, based on imaging or pathology. 4/5 patients with moderate to high T cell infiltrates at baseline had partial (2) or complete responses (2) based on imaging (surgery pending), one of whom had absence of DCIS on post-therapy core biopsy and a clear MRI 4 months later. Correlative studies (immune cell densities, spatial proximities) will be presented at the meeting along with complete data (including post-treatment pathology) on the first 8 patients. Side effects were independent of response and included Gr1/2 fever, myalgias, and fatigue starting within 12 hours of injection (3-4 days), enlargement of regional nodes by day 2, and Gr 1/2 erythema and induration of the breast starting at 4 days and lasting 4-20 days. Earlier onset and persistence of symptoms with subsequent exposure required dose reductions for the majority of patients to maintain tolerability (avoid fevers over 39.4°C, intense erythema and swelling of the breast lasting > 4 days). No AEs were higher than grade 2. Conclusion: The combination of intralesional pembro and mRNA-2752 demonstrated modulation of the tumor immune microenvironment and robust antitumor activity in high-risk DCIS (typically HR- or HER2+) with existing T cell infiltrates. This is an ongoing study; the optimal Phase 2 dose for the combination will be based on the totality of evolving safety and translational data. Citation Format: Laura J. Esserman, Alexa Glencer, Kirithiga Ramalingam, Christopher J. Schwartz, Alexander Borowsky, Gillian L. Hirst, Rachel Woody, Nicole Schindler, Nola M. Hylton, Michael Campbell. Intralesional injection of anti-PD-1 (pembrolizumab) and OX40L/IL-23/IL-36 mRNAs (mRNA-2752) results in regression of DCIS characterized by lymphocytic infiltrates [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr OT1-20-02.

Supplementary Table 2

Ductal carcinoma in situ (DCIS) is a biologically heterogenous entity with uncertain risk for invasive ductal carcinoma (IDC) development. Standard treatment is surgical resection often followed by radiation. New approaches are needed to reduce overtreatment. This was an observational study that enrolled patients with DCIS who chose not to pursue surgical resection from 2002 to 2019 at a single academic medical center. All patients underwent breast MRI exams at 3- to 6-month intervals. Patients with hormone receptor–positive disease received endocrine therapy. Surgical resection was strongly recommended if clinical or radiographic evidence of disease progression developed. A recursive partitioning (R-PART) algorithm incorporating breast MRI features and endocrine responsiveness was used retrospectively to stratify risk of IDC. A total of 71 patients were enrolled, 2 with bilateral DCIS (73 lesions). A total of 34 (46.6%) were premenopausal, 68 (93.2%) were hormone-receptor positive, and 60 (82.1%) were intermediate- or high-grade lesions. Mean follow-up time was 8.5 years. Over half (52.1%) remained on active surveillance without evidence of IDC with mean duration of 7.4 years. Twenty patients developed IDC, of which 6 were HER2 positive. DCIS and subsequent IDC had highly concordant tumor biology. Risk of IDC was characterized by MRI features after 6 months of endocrine therapy exposure; low-, intermediate-, and high-risk groups were identified with respective IDC rates of 8.7%, 20.0%, and 68.2%. Thus, active surveillance consisting of neoadjuvant endocrine therapy and serial breast MRI may be an effective tool to risk-stratify patients with DCIS and optimally select medical or surgical management.Significance:A retrospective analysis of 71 patients with DCIS who did not undergo upfront surgery demonstrated that breast MRI features after short-term exposure to endocrine therapy identify those at high (68.2%), intermediate (20.0%), and low risk (8.7%) of IDC. With 7.4 years mean follow-up, 52.1% of patients remain on active surveillance. A period of active surveillance offers the opportunity to risk-stratify DCIS lesions and guide decisions for operative management.

The increased detection and treatment of early stage breast cancer as well as ductal carcinoma in situ (DCIS) has not led to significant survival benefits. Therefore, the current standard treatment of DCIS is questionable. An informed evidence-based treatment strategy, and likely de-escalation from the current standards requires new prognostic models built from more comprehensive characterization with objective criteria. Parallel profiling of the molecular landscape and micro-environment in pure DCIS remains challenging due to histological heterogeneity and the inevitable reliance on small archived specimens. Leveraging recent methodological advances, we characterized the mutational, transcriptional, histological and microenvironmental landscape across multiple micro-dissected regions from 39 cases to generate a multi-modal breast precancer atlas. The histological architecture was associated with grade, adiposity, and intrinsic expression subtypes. Similar to previous findings, high-grade lesions had higher mutational burden, including TP53 mutations, while low-grade lesions had more frequent 16q losses and GATA3 mutations. Multi-region analysis revealed most somatic alterations, including whole genome duplication events, were clonal, but genetic divergence increased with distance between regions. In 7/12 evaluable cases, somatic mutations in putative driver genes affected a subset of regions only. This genetic heterogeneity often accompanied phenotypic heterogeneity and regions with low risk features (Normal-like, Luminal A) occurred earlier than those with high-risk features (Her2-like, Basal or necrosis) according to the phylogenetic analysis. The immune-environment was evaluated using multiplex immuno-histochemistry to measure relative stromal and epithelial densities of B lymphocyte (B-cell), T lymphocyte (T-cell) and regulatory T cells (T-reg) and identify 3 immune-states: Active, Suppressed and Excluded (lower epithelial density). All states included both DCIS and adjacent benign regions, and none associated with intrinsic subtypes. The Excluded state was enriched in high-grade DCIS and, compared to benign areas, more likely acquired in DCIS, showing transcriptional evidence of stronger immune-suppression and possible evasion. The breast pre-cancer atlas therefore reveals correlated levels of phenotypic and genotypic heterogeneity, including at sub-histological resolution. These uniquely integrated observations will help scope future studies, prioritize candidate markers for progression risk modelling and identify functional similarities in precursor lesions from other types of adenocarcinomas.

HER2-targeted therapy dramatically improves outcomes in early breast cancer. Here we report the results of two HER2-targeted combinations in the neoadjuvant I-SPY2 phase 2 adaptive platform trial for early breast cancer at high risk of recurrence: ado-trastuzumab emtansine plus pertuzumab (T-DM1/P) and paclitaxel, trastuzumab and pertuzumab (THP). Eligible women have >2.5 cm clinical stage II/III HER2+ breast cancer, adaptively randomized to T-DM1/P, THP, or a common control arm of paclitaxel/trastuzumab (TH), followed by doxorubicin/cyclophosphamide, then surgery. Both T-DM1/P and THP arms ‘graduate’ in all subtypes: predicted pCR rates are 63%, 72% and 33% for T-DM1/P (n = 52), THP (n = 45) and TH (n = 31) respectively. Toxicity burden is similar between arms. Degree of HER2 pathway signaling and phosphorylation in pretreatment biopsy specimens are associated with response to both T-DM1/P and THP and can further identify highly responsive HER2+ tumors to HER2-directed therapy. This may help identify patients who can safely de-escalate cytotoxic chemotherapy without compromising excellent outcome., HER2-targeted therapy improves patient’s outcome in early breast cancer. Here, the authors present the efficacy and biomarker analysis of two HER2-targeted combinations (ado-trastuzumab emtansine plus pertuzumab and paclitaxel, trastuzumab and pertuzumab) in the context of the neoadjuvant I-SPY2 phase 2 adaptive platform trial for early breast cancer at high risk of recurrence.

Ductal carcinoma in situ (DCIS) is a biologically heterogenous entity with uncertain risk for invasive ductal carcinoma (IDC) development. Standard treatment is surgical resection often followed by radiation. New approaches are needed to reduce overtreatment. This was an observational study that enrolled patients with DCIS who chose not to pursue surgical resection from 2002 to 2019 at a single academic medical center. All patients underwent breast MRI exams at 3- to 6-month intervals. Patients with hormone receptor–positive disease received endocrine therapy. Surgical resection was strongly recommended if clinical or radiographic evidence of disease progression developed. A recursive partitioning (R-PART) algorithm incorporating breast MRI features and endocrine responsiveness was used retrospectively to stratify risk of IDC. A total of 71 patients were enrolled, 2 with bilateral DCIS (73 lesions). A total of 34 (46.6%) were premenopausal, 68 (93.2%) were hormone-receptor positive, and 60 (82.1%) were intermediate- or high-grade lesions. Mean follow-up time was 8.5 years. Over half (52.1%) remained on active surveillance without evidence of IDC with mean duration of 7.4 years. Twenty patients developed IDC, of which 6 were HER2 positive. DCIS and subsequent IDC had highly concordant tumor biology. Risk of IDC was characterized by MRI features after 6 months of endocrine therapy exposure; low-, intermediate-, and high-risk groups were identified with respective IDC rates of 8.7%, 20.0%, and 68.2%. Thus, active surveillance consisting of neoadjuvant endocrine therapy and serial breast MRI may be an effective tool to risk-stratify patients with DCIS and optimally select medical or surgical management. Significance: A retrospective analysis of 71 patients with DCIS who did not undergo upfront surgery demonstrated that breast MRI features after short-term exposure to endocrine therapy identify those at high (68.2%), intermediate (20.0%), and low risk (8.7%) of IDC. With 7.4 years mean follow-up, 52.1% of patients remain on active surveillance. A period of active surveillance offers the opportunity to risk-stratify DCIS lesions and guide decisions for operative management.

BACKGROUND We proposed that a test for sensitivity to the adjuvant endocrine therapy component of treatment for patients with stage II-III breast cancer (SET2,3) should measure transcription related to estrogen and progesterone receptors (SETER/PR index) adjusted for a baseline prognostic index (BPI) combining clinical tumor and nodal stage with molecular subtype by RNA4 (ESR1, PGR, ERBB2, and AURKA). PATIENTS AND METHODS Patients with clinically high-risk, hormone receptor-positive (HR+), human epidermal growth factor receptor 2 (HER2)-negative (HR+/HER2-) breast cancer received neoadjuvant taxane-anthracycline chemotherapy, surgery with measurement of residual cancer burden (RCB), and then adjuvant endocrine therapy. SET2,3 was measured from pre-treatment tumor biopsies, evaluated first in an MD Anderson Cancer Center (MDACC) cohort (n = 307, 11 years' follow-up, U133A microarrays), cut point was determined, and then independent, blinded evaluation was carried out in the I-SPY2 trial (n = 268, high-risk MammaPrint result, 3.8 years' follow-up, Agilent-44K microarrays, NCI Clinical Trials ID: NCT01042379). Primary outcome measure was distant relapse-free survival. Multivariate Cox regression models tested prognostic independence of SET2,3 relative to RCB and other molecular prognostic signatures, and whether other prognostic signatures could substitute for SETER/PR or RNA4 components of SET2,3. RESULTS SET2,3 added independent prognostic information to RCB in the MDACC cohort: SET2,3 [hazard ratio (HR) 0.23, P = 0.004] and RCB (HR 1.77, P < 0.001); and the I-SPY2 trial: SET2,3 (HR 0.27, P = 0.031) and RCB (HR 1.68, P = 0.008). SET2,3 provided similar prognostic information irrespective of whether RCB-II or RCB-III after chemotherapy, and in both luminal subtypes. Conversely, RCB was most strongly prognostic in cancers with low SET2,3 status (MDACC P < 0.001, I-SPY2 P < 0.001). Other molecular signatures were not independently prognostic; they could effectively substitute for RNA4 subtype within the BPI component of SET2,3, but they could not effectively substitute for SETER/PR index. CONCLUSIONS SET2,3 added independent prognostic information to chemotherapy response (RCB) and baseline prognostic score or subtype. Approximately 40% of patients with clinically high-risk HR+/HER2- disease had high SET2,3 and could be considered for clinical trials of neoadjuvant endocrine-based treatment.

Introduction: One of the principal limiting factors to achieving cures in patients with cancer is drug resistance. Drug repositioning is the application of FDA-approved drug compounds for novel indications beyond the scope of the drug’s original intended use. This approach offers advantages over traditional drug development by reducing development costs and providing shorter paths to approval, as drug safety has already been established during the drug’s original regulatory process. One approach for computational drug repositioning involves generating a disease gene expression signature and then identifying a drug that can reverse this disease signature. In this study, we extracted drug resistance signatures from the I-SPY 2 TRIAL by comparing gene expression profiles of responder and non-responder patients stratified by treatment and molecular subtype. We then applied our drug repositioning pipeline to predict compounds that can reverse the gene expression profiles of these drug resistance signatures. We hypothesize that reversing these drug resistance signatures will resensitize tumors to treatment and improve patient outcome. Methods: We first generated the drug resistance signatures by performing differential expression between responders (RCB 0/I) and non-responders (RCB III) within treatment arms and molecular subtypes. An optimal log fold-change cutoff was selected for each signature by identifying the cutoff that best separates the responder and non-responder samples using k-means clustering. We then applied our drug repositioning pipeline to identify compounds that significantly reverse these signatures using the drug perturbation profiles generated in a breast cancer cell line in the Connectivity Map v2 dataset. Briefly, the pipeline uses a non- parametric, rank-based pattern-matching strategy based on the Kolmogorov-Smirnov (KS) statistic to assess the enrichment of resistance genes in a ranked drug gene expression list. Significance of each prediction is estimated from a null distribution of scores generated from random gene signatures. Results: We found that few individual genes are shared among the resistance signatures across the treatment arms and molecular subtypes, with the most common genes present in only 5/17 of the treatment arm and molecular subtype groups. At the pathway-level, however, we found that immune-related pathways are generally enriched among the responders and estrogen-response pathways are generally enriched among the non-responders. Although most of our drug predictions are unique to treatment arms and molecular subtypes, our drug repositioning pipeline identified the selective estrogen receptor degrader (SERD) fulvestrant as a compound that can potentially reverse resistance across a majority of the treatment arms and molecular subtypes. Conclusion: We applied our drug repositioning pipeline to identify novel agents to sensitize drug-resistant tumors in the I-SPY 2+ clinical trial and identified a SERD, fulvestrant, as a potential candidate for multiple molecular subtypes and treatment arms. Citation Format: Katharine Yu, Amrita Basu, Christina Yau, Denise Wolf, Gillian Hirst, Laura Sit, Nicholas O’Grady, Thelma Brown, I-SPY 2 TRIAL Investigators, Angela DeMichele, Don Berry, Nola Hylton, Doug Yee, Laura Esserman, Laura van 't Veer, Marina Sirota. Computational drug repositioning for the identification of new agents to sensitize drug-resistant breast tumors across treatment arms and molecular subtypes [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 PS11-04.

Author(s): Magbanua, MJM; Swigart, LB; Wu, H-T; Hirst, GL; Yau, C; Wolf, DM; Tin, A; Salari, R; Shchegrova, S; Pawar, H; Delson, AL; DeMichele, A; Liu, MC; Chien, AJ; Tripathy, D; Asare, S; Lin, C-HJ; Billings, P; Aleshin, A; Sethi, H; Louie, M; Zimmermann, B; Esserman, LJ; van 't Veer, LJ | Abstract: BackgroundPathologic complete response (pCR) to neoadjuvant chemotherapy (NAC) is strongly associated with favorable outcome. We examined the utility of serial circulating tumor DNA (ctDNA) testing for predicting pCR and risk of metastatic recurrence.Patients and methodsCell-free DNA (cfDNA) was isolated from 291 plasma samples of 84 high-risk early breast cancer patients treated in the neoadjuvant I-SPY 2 TRIAL with standard NAC alone or combined with MK-2206 (AKT inhibitor) treatment. Blood was collected at pretreatment (T0), 3 weeks after initiation of paclitaxel (T1), between paclitaxel and anthracycline regimens (T2), or prior to surgery (T3). A personalized ctDNA test was designed to detect up to 16 patient-specific mutations (from whole-exome sequencing of pretreatment tumor) in cfDNA by ultra-deep sequencing. The median follow-up time for survival analysis was 4.8 years.ResultsAt T0, 61 of 84 (73%) patients were ctDNA positive, which decreased over time (T1: 35%; T2: 14%; and T3: 9%). Patients who remained ctDNA positive at T1 were significantly more likely to have residual disease after NAC (83% non-pCR) compared with those who cleared ctDNA (52% non-pCR; odds ratio 4.33, Pn= 0.012). After NAC, all patients who achieved pCR were ctDNA negative (nn= 17, 100%). For those who did not achieve pCR (nn= 43), ctDNA-positive patients (14%) had a significantly increased risk of metastatic recurrence [hazard ratio (HR) 10.4; 95% confidence interval (CI) 2.3-46.6]; interestingly, patients who did not achieve pCR but were ctDNA negative (86%) had excellent outcome, similar to those who achieved pCR (HR 1.4; 95% CI 0.15-13.5).ConclusionsLack of ctDNA clearance was a significant predictor of poor response and metastatic recurrence, while clearance was associated with improved survival even in patients who did not achieve pCR. Personalized monitoring of ctDNA during NAC of high-risk early breast cancer may aid in real-time assessment of treatment response and help fine-tune pCR as a surrogate endpoint of survival.

Background: Metastatic staging imaging is not recommended for asymptomatic patients with stage I–II breast cancer. Greater distant metastatic disease risk may warrant baseline imaging in patients with stage II–III with high-risk biologic subtypes. NCCN Guidelines recommend considering CT of the chest, abdomen, and pelvis (CT CAP) and bone scan in appropriate patients. CT CAP and bone scan are considered standard of care (SoC), although PET/CT is a patient-centered alternative. Methods: Data were available for 799 high-risk patients with clinical stage II–III disease who initiated screening for the I-SPY2 trial at 4 institutions. A total of 564 complete records were reviewed to compare PET/CT versus SoC. Costs were determined from the payer perspective using the national 2018 Medicare Physician Fee Schedule and representative reimbursements to the University of California, San Francisco (UCSF). Incremental cost-effectiveness ratio (ICER) measured cost of using PET/CT per percent of patients who avoided a false-positive (FP). Results: The de novo metastatic disease rate was 4.6%. Imaging varied across the 4 institutions (PP=.0009). Mean time between incidental finding on baseline imaging to FP determination was 10.8 days. Mean time from diagnosis to chemotherapy initiation was 44.3 days with SoC versus 37.5 days with PET/CT (P=.0001). Mean cost per patient was $1,132 (SoC) versus $1,477 (PET/CT) using the Medicare Physician Fee Schedule, with an ICER of $31. Using representative reimbursements to UCSF, mean cost per patient was $1,236 (SoC) versus $1,073 (PET/CT) for Medicare, and $3,083 (SoC) versus $1,656 (PET/CT) for a private payer, with ICERs of −$15 and −$130, respectively. Conclusions: Considerable variation exists in metastatic staging practices. PET/CT reduced FP risk by half and decreased workup of incidental findings, allowing for earlier treatment start. PET/CT may be cost-effective, and at one institution was shown to be cost-saving. Better alignment is needed between hospital pricing strategies and payer coverage policies to deliver high-value care.

Background: The SET2,3 index combines an accurate measure of transcription related to both estrogen and progesterone receptors (SETER/PR index) with a baseline prognostic index (BPI) derived from c-T Stage, c-N status and molecular subtype by RNA4 (ESR1, PGR, ERBB2, and AURKA). SET2,3 index was translated from a microarray-based signature to a customized hybridization assay that yields highly reproducible results from routine pathology tissue blocks. Methods: The SET2,3 index was calculated from microarray data prepared from baseline biopsies of HR+/HER2- cancers prior to neoadjuvant taxane-anthracycline chemotherapy followed by adjuvant endocrine therapy in: 1) a test set of 307 samples from the MDACC cohort with 8 years median follow-up (Affymetrix U133A microarrays, Symmans et al JAMA 2011), and 2) an independent blinded validation set of 268 high-risk Mammaprint (MP) samples from the I-SPY2 clinical trial with 3.8 years median follow-up (Agilent 44K microarrays, Agendia). The cut-point for high versus low SET2,3 was defined in the MDACC cohort and then tested in the I-SPY2 cohort. Association between the SET2,3 index and distant relapse-free survival (DRFS) was evaluated in each cohort using multivariate Cox regression models. One model adjusted for residual cancer burden (RCB) after neoadjuvant chemotherapy and its interaction with the SET2,3 index, also including treatment arm (experimental vs. control) in the I-SPY 2 trial. Another model adjusted for other prognostic gene expression signatures (GES) for recurrence score (RS), MP, or endopredict (EP) in the MDACC cohort, and actual MP in the I-SPY2 trial. A third model tested the ability of prognostic GES to substitute for RNA4 subtype (part of BPI) or SETER/PR index as components of the SET2,3 index. Results: Predicted sensitivity to endocrine therapy (SET2,3) and response to neoadjuvant chemotherapy (RCB) were independently prognostic, with nonsignificant (NS) interaction term, in multivariate analyses of the MDACC study: SET2,3 HR 0.26 (p=0.016); RCB HR 2.04 (p Conclusions: SET2,3 index of endocrine transcriptional activity in a pre-treatment core biopsy added independent significant prognostic information to any baseline prognostic score and response to neoadjuvant chemotherapy. Approximately 40% of clinical or genomic (MP) high-risk HR+/HER2- cancers had high SET2,3 index, and their response to neoadjuvant chemotherapy (RCB class) was not prognostic. This suggests that SET2,3 index might be used to select appropriate candidates for endocrine-based neoadjuvant treatments in clinical trials. Citation Format: Lili Du, Christina Yau, Lamorna Brown-Swigart, Rebekah Gould, Gillian L Hirst, I-SPY2 Consortium, Marieke van der Noordaa, Isabelle Bedrosian, Rachel M Layman, Vicente Valero, Laura van't Veer, Laura Esserman, W. Fraser Symmans. Prognostic contribution of predicted sensitivity to endocrine therapy (SET) prior to neoadjuvant chemotherapy for stage II-III hormone receptor-positive and HER2-negative (HR+/HER2-) breast cancer [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 P2-11-04.

Introduction: Ductal carcinoma in situ (DCIS) is a pre-malignant lesion but 14-53% will not progress to an invasive cancer. Large, well characterized DCIS datasets with long term follow up are sparse, and there is uncertainty regarding the long term effects of various treatment modalities on subsequent breast events (SBE). Here, we analyze trends identified in the SBE rates from patients treated at two large academic breast care centers in California, UCSF and UCSD. Methods: Institutional Cancer Registries were used to collect demographic, clinical, imaging and pathologic data. Patients aged 18 years and older without any prior history of breast disease whose first diagnosed breast neoplasm was DCIS and who had at least 6 months of follow up were included. Only SBE beyond 6 months after initial diagnosis were included. All mastectomy types and associated adjuvant treatment were grouped. All patients not undergoing surgery were grouped. Differences between patients in the various treatment groups were assessed using χ2, Student’s t-test, and one-way ANOVA. Poisson regression was used to compare differences in SBE rates between treatment groups. For analysis, follow up times were divided into three 5 years periods (0-5, 6-10, 11-15 years) after initial DCIS diagnosis. Results: 2730 patients - 1575 (57.7%) at UCSF and 1155 (42.3%) at UCSD - were diagnosed between 1985 and 2017 and included in the study. 1910 (70.0%) underwent breast conserving surgery (BCS), 672 (24.6 %) had mastectomy, 144 (5.3%) did not have surgery, and 4 (0.1%) had missing surgery status. 623 (22.8%) received adjuvant endocrine therapy (ET), 2081 (76.2%) did not and 26 (1.0%) had missing adjuvant endocrine therapy status. 1092 (40.0%) received adjuvant radiation therapy (RT), 1619 (59.3%) did not and 19 (0.7%) had unknown radiation therapy status. Median follow up time for all patients was 7.9 years. 305 patients were diagnosed with SBE. Of these, 144 (47.2%) were in situ and 147 (48.2%) were invasive including 16 (5.2%) metastatic lesions, and 14 (4.6%) had missing invasiveness. Of the 289 patients who did not have a metastatic second lesion, 176 (60.9%) SBE were ipsilateral, 88 (30.4%) were contralateral, and 25 (8.7%) had missing SBE laterality. The overall incidence (i) for any SBE over the entire study period was 1.4%/yr. Compared to women who were treated with BCS alone (N=642, i=2.14%/yr, 95% CI 1.76-2.51), SBE rates were lower in women undergoing BCS with RT (N=719, i=1.13%/yr, 95% CI 0.87-1.40, p Conclusion: This large two-center registry study reveals that the rate of invasive and in situ SBE after an initial DCIS diagnosis are comparable. The effect of each treatment modality on SBE incidence rates are consistent with other published studies, with the notable exception of BCS and ET which requires deeper investigation. As expected, local treatment affects mostly ipsilateral events within the first 5 years after initial diagnosis, without impacting the rate of contralateral SBE. Complementary molecular and cellular profiling of selected specimens are underway to help build a more precise BSE risk model and prevent overtreatment. Citation Format: Thomas O'Keefe, Christina Yau, Eliza Jeong, Emma Iaconetti, Paul Kim, Ann Griffin, Joseph McGuire, Rita Mukhtar, Laura Esserman, Olivier Harismendy, Gillian L. Hirst. Risk of subsequent events after initial diagnosis of ductal carcinoma in situ - A large multi-center registry study [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 P5-08-05.

Background: Ductal carcinoma in situ (DCIS) now represents nearly a quarter of newly diagnosed breast cancers in the United States. Standard-of-care treatment for DCIS is aggressive local therapy consisting of either mastectomy or breast conserving surgery with radiation. However, DCIS mortality is low regardless of initial treatment, suggesting opportunities to explore a spectrum of treatment options. With these treatment options, there is the potential to create risk-adapted treatment plans, but the question of how to assess risk remains. Molecular tests can help to personalize treatment by stratifying disease sub-types and providing prognosis. One such tool is the Oncotype DX® Breast DCIS Score, a risk measure which was validated in a meta-analysis of 773 patients from the E5194 and Ontario DCIS Cohort studies. Along with calculating a Breast DCIS Score™ from the expression levels of 12 genes, the test provides a predicted 10-year risk of local recurrence from the score result, age, and tumor size for patients who receive breast conserving surgery alone. Understanding how such a tool might impact decision-making will inform its implementation. Eligibility & trial design: The ATHENA Breast Health Network is a consortium of the five University of California Medical centers. Through ATHENA, patients with histologically confirmed DCIS and no concurrent invasive cancer are approached to participate in the Athena DCIS Registry. Patients in the registry facing an active management decision are eligible to participate in the Oncotype DX® DCIS prospective study. Specific aims: The primary aim of the study is to determine whether the additional diagnostic information (i.e. the DCIS Score™) impacts patient treatment decisions and physician recommendation. Additional goals are to correlate the DCIS Score™ with mammographic findings, pathological variables, and treatment recommendations, and to estimate risk within each DCIS Score™ group. Participants and their physicians answer survey questions both before and after receiving the score to evaluate the impact of the DCIS Score™ on treatment recommendations and decisions. Statistical methods: The study will assess the percentage of patients who thought the DCIS risk score influenced their treatment decision. The study will also assess whether a significant proportion of physicians changed their recommendations after considering the DCIS Score™ using the chi-square test. Similarly, the patients’ preferred treatment option pre- and post- test surveys will be evaluated. In addition, the concordance between physicians’ and patients’ choices will be assessed by the Kappa statistic before and after the score. The patients’ and physicians’ confidence levels in their treatment recommendation and decision pre- and post- test will be compared using a Wilcoxon signed-rank test, as well as the percentage of patients and physicians who are glad they used the test. In addition, the study will assess whether the DCIS test influences a patient’s perception of their recurrence risk by comparing the self-reported 10-year breast cancer recurrence risk in their pre- and post- test questionnaires using a Wilcoxon signed-rank test. Current and target accrual: The current accrual across all sites in the Oncotype study is 94 patients. The target accrual for the initial pilot phase data is defined as the first 100 patients accrued. If interested in learning more about the study, please contact Rita Mukhtar, MD (Rita.Mukhtar@ucsf.edu). Citation Format: Jane M Wei, Paul Kim, Cheryl Ewing, Jasmine Wong, Laura J Esserman, Michael D Alvarado, Abimbola O Olusanya, Skye Stewart, Ashley Tydon, Parima Daroui, Jeffrey V Kuo, Hannah L Park, Karen T Lane, Eliza Jeong, Kelsey Brown, Ava Hosseini, Barbara A Parker, Sarah L Blair, Athena Breast Health Network Investigators, Frederick Baehner, Olivier Harismendy, Antonia Petruse, Carlie K Thompson, Helena R Chang, Alexander D Borowsky, Christina Yau, Gillian L Hirst, Richard J Bold, Rita A Mukhtar. Use of Oncotype DX DCIS for disease management in a prospective DCIS registry [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 OT3-09-01.

Background: Machine learning relies on algorithms that learn patterns in large, complex datasets to predict outcomes. The adaptive, neoadjuvant I-SPY 2 TRIAL evaluates novel agents added to standard therapy, and identifies their most responsive subtype. While previously proposed genes/signatures reflecting an agent’s mechanism of action predicted pathologic complete response (pCR) in some treatment arms/subtypes, not all arms had strong predictive biomarkers. We leverage machine learning to explore the limitations of using only known mechanisms of action in predicting pCR, and the extent to which biology outside known drug action improves response prediction in the first 10 arms of the trial. Methods: Our study involves 986 patients with pre-treatment gene expression and pCR data across 10 treatment arms including inhibitors of HER2: neratinib (N), pertuzumab (P), TDM1/P; AKT (MK-2206; M); IGF1R (ganitumab); HSP90 (ganetespib); PARP/DNA repair (veliparib/carboplatin; VC); ANG1/2 (AMG386); immune checkpoints (pembrolizumab; Pembro); and a shared control arm (Ctr). Each arm/receptor subtype group was evaluated independently for groups with at least 20 patients (n=19), with 25% of data held out as independent test sets. We implemented a 3-fold cross validation technique with 10 repeats using Random Forest ensemble algorithm with recursive feature elimination. In combination with clinical data, a three-pronged feature-selection approach was employed: (1) restricted to mechanism of action genes: AKT/PI3K/HER (m=10 genes), IGF1 (m=11), HSP90 (m=88), DNA repair (m=79), TIE1/2 (m=11), and immune (m=61), as well as HER2 amplicon genes; (2) expanded to include targeted pathways for all 10 agents/combinations plus ESR1 and proliferation genes (m=339); (3) an unbiased whole genome approach (m=17,990). Models were considered predictive if AUROC ≥ 0.75, Sensitivity ≥ 0.6 and Specificity ≥ 0.6 in cross validation and independent test sets. Results: Table 1 summarizes the results of our analysis (Yes=predictive; NA=no/insufficient data). Prediction of pCR using only genes reflecting the known mechanism of the drug succeeded in 5 subgroups, with DNA repair genes predicting VC response and immune genes predicting Pembro response in HR+HER2- and HR-HER2- subsets, and AKT/PI3K/HER + HER2 amplicon genes predicting (P) response in HR+HER2+ patients. Expansion of the feature set to include genes associated with all mechanisms of action of all drugs proved sufficient to produce good predictive models in 8 of 19 subgroups. Examples include DNA repair + immune genes predicting response to ganitumab in HR+HER2- and to (N) in HR+HER2+. An unbiased approach using all data yielded predictive power in 8 of 19 subgroups, including 5 with no predictive models from the first two approaches. Examples include HR-HER2- (N) predictors enriched for metabolic, cell division and membrane protein proteolytic processes; HR+HER2+ TDM1/P enriched for metabolic, stress response and cell cycle processes; and HR-HER2- MK-2206 predictors containing Ser/Thr kinases. In total, we identify predictive biomarkers in 14 of 19 subgroups across the three feature selection approaches. Conclusion: Our results suggests that hypothesis driven analysis restricted to assumed mechanisms of action of the experimental agents may be insufficient, and that exploration of possible off target effects may be needed to understand the underlying biology of response or resistance. Table 1. Model results across feature selection approachesHR+HER2-HR-HER2-HR+HER2+HR-HER2+Number of PatientsMechanism of ActionAll Mechanisms of ActionUnbiasedNumber of PatientsMechanism of ActionAll Mechanisms of ActionUnbiasedNumber of PatientsMechanism of ActionAll Mechanisms of ActionUnbiasedNumber of PatientsMechanism of ActionAll Mechanisms of ActionUnbiasedneratinib (pan anti-HER)NA32NoNoYes42NoYesYes23NoNoYespertuzumab (anti-HER2)NANA29YesYesNoNATDM1/Pertuzumab (anti-HER2)NANA35NoNoYesNAMK−2206 (AKT inhibitor)28NoNoNo32NoNoYesNANAganitumab (IGFR inhibitor)58NoYesNo48NoNoNoNANAganetespib (HSP90 inhibitor)48NoYesYes45NoNoNoNANAvelirapib/carboplatin (PARP inhibitor/DNA damage)33YesYesNo39YesYesNoNANAAMG386 (ANG1/2 inhibitor)62NoYesYes53NoNoNoNANApembrolizumab (immune checkpoint inhibitor)38YesYesNo29YesNoNoNANAHER2+ controlNANANANAHER2- control94NoNoYes84NoNoNoNANA Citation Format: Rosalyn W. Sayaman, Denise M. Wolf, Christina Yau, Julie Wulfkuhle, Emanuel Petricoin, Lamorna Brown-Swigart, Smita M. Asare, Gillian L. Hirst, Laura Sit, Nicholas O'Grady, Diane Hedistian, I-SPY 2 TRIAL Consortium, Laura J. Esserman, Mark A. LaBarge, Laura J van 't Veer. Application of machine learning to elucidate the biology predicting response in the I-SPY 2 neoadjuvant breast cancer trial [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 P1-21-08.

Background: A variety of investigational HER2-inhibitor agents/combinations have been tested in I-SPY 2, including neratinib (N), TDM1 combined with pertuzumab (P) (TDM1/P), and trastuzumab (H) combined with pertuzumab (H/P; prior to this combination becoming standard of care), all with trastuzumab as control (Ctr). All three experimental arms graduated, showing improved efficacy over control in one or more receptor subsets (HR+HER2+, HR-HER2+, or/and HER2+). Here we assess 10 biomarkers in the HER2, ER/PR, and proliferation pathways on multiple levels of resolution (expression, protein, phospho-protein) as predictors of response in these four arms, hypothesizing that highly HER2-activated, proliferative tumors may be more sensitive to HER2-inhibition than those that are more luminal and quiescent. Methods: 192 HER2+ patients were considered in this analysis: (31 Ctr, 65 N, 52 TDM1/P, and 44 H/P). 10 biomarkers relating to HER2, ER, or proliferation were evaluated from pre-treatment biopsies: HER2 IHC (n=145), 3 expression signatures (n=192), BluePrint subtype (n=192), and 5 protein/phospho-protein analytes by RPPA (n=175). Each biomarker was tested for association with pCR in the whole population and within each arm using a logistic model. This analysis was adjusted for HR status and treatment arm as covariates, and performed within receptor subtypes. This analysis does not adjust for multiplicities of other biomarkers. Results: In the population as a whole, HER2 and HER2-signaling biomarkers, evaluated at multiple levels of resolution: IHC, total-/phospho-protein by RPPA, and mRNA (HER2 amplicon module) - are highly correlated (rho=0.8 [0.65-0.92]). Higher HER2 levels and activity are associated with response: HER2 IHC 3+ status (LR p=0.00032), total quantitative ERBB2 protein by RPPA (LR p=5.4E-09), ERBB2 activation levels (LR p=6.58E-06 (pERBB2 (Y1248)) and 9.95E-06 (pEGFR Y1173)), and the ERBB2 amplicon expression signature (LR p=2.38E-08). In contrast, higher average ER/PR expression associates with non-response to HER2-targeted therapy (LR p=4.28E-08). Both HER2 and ER/PR signaling phenotypes are captured by BluePrint subtyping; and consistent with the individual pathway markers, tumors classified Luminal-type had a lower pCR rate relative to those classified as Her2-type (or Basal-type) (LR p=4.84E-11). These associations all retain significance in a model adjusting for HR status and treatment arm, and in the HR+HER2+ subset. In addition, we quantitatively assessed proliferation markers at the total protein (RPPA: Ki67), phospho-protein (pAURKA) and mRNA (proliferation signature Module11_Prolif) levels. All three proliferation biomarkers predict response overall; but this association is strongest within the HR+HER2+ subset (LR p=0.0012 (Module11_prolif), 0.0036 (pAURK), and 0.045 (Ki67)). None of the biomarkers tested were associated with response in the HR-HER2+ subset. Numbers are small within individual arms. Within the HR+HER2+ subtype, higher HER2 and lower ER/PR is observed in responders in all experimental arms; but the proliferation markers Module11_Prolif (LR p=0.0031) and Ki67 total protein (LR p=0.0029) are associated with response to TDM1/P but not H/P or N. Conclusion: High HER2 signaling at the expression, protein, and phospho-protein levels, and low ER signaling, all predict response to HER2-inhibition across treatment arms. Proliferation markers may be useful for prioritizing therapies in the HR+HER2+ subset. Citation Format: Denise M Wolf, Christina Yau, Julia Wulfkuhle, Lamorna Brown-Swigart, Smita M. Asare, Gillian L. Hirst, Laura Sit, Jane Perlmutter, I-SPY 2 TRIAL Consortium, Minetta Liu, John Park, Angela DeMichele, Douglas Yee, Don Berry, Laura Esserman, Emanuel Petricoin, Laura van t' Veer. HER2 signaling, ER, and proliferation biomarkers predict response to multiple HER2-targeted agents/combinations plus standard neoadjuvant therapy in the I-SPY 2 trial [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 P4-10-02.

Purpose Standard treatment for ductal carcinoma in situ (DCIS) involves surgical excision and radiation treatment, and often adjuvant endocrine therapy (ET). However, this may constitute overtreatment for some women. The purpose of this neoadjuvant ET study in patients with biopsy-proven DCIS was to evaluate the relationship between the primary outcome of upstaging at surgery (invasive disease) and changes in the pre- and post-ET MRI appearances of both (1) lesion and (2) background parenchymal enhancement (BPE), with the goal to better inform de-escalated therapy. Methods Outcomes of patients with DCIS who were prospectively enrolled in a neoadjuvant ET trial between 2002 and 2009 were retrospectively analyzed with IRB approval. All patients had dynamic contrast-enhanced breast MRI prior to and following an average of 3.1 months of ET (range 1.9 – 5 months), followed by surgical excision within one year of the second MRI. Pathology reports were used to confirm initial biopsy results and to determine the nature and extent of disease postoperatively. Surgeon and radiologist’s reports were used to assess improvement of lesion after ET based on 1) less prominently enhancing pattern or 2) reduction in size of DCIS lesion after treatment. BPE response to ET on imaging was assessed by two radiologists specialized in breast imaging who compared pre- and post-ET MRI’s, blinded to all imaging reports. The change in BPE of the ipsilateral breast with treatment was scored subjectively as increased, decreased, or unchanged. Readers reached a consensus on discordant classifications of the change in BPE. The correlation between imaging change (of lesion and BPE) and incidence of invasive ductal carcinoma (IDC) at surgery was determined using Fisher’s exact test. Results: Of 34 patients evaluated, six (18%) had IDC at surgery. The prevalence of IDC in each group is shown in Table 2. Those with improvement of lesion on MRI had a lower likelihood of IDC at surgery compared to patients with no imaging improvement (Table 2, p= 0.048). Addition of change in BPE to the evaluation of lesion improvement significantly increased the chance of identifying specific patients who were much more likely to have an underlying invasive cancer at surgery (Table 2, p= 0.032). The risk of having IDC at surgery was considerably higher in the group whose lesion was assessed as not improved and who had decreased BPE scores on MRI (Table 2, p= 0.018). Conclusion: In our unique population of patients with mostly ER+ DCIS receiving pre-operative endocrine therapy, the combination of lack of lesion improvement and reduction in BPE score in blinded reads was significantly associated with the finding of invasive disease at surgical excision. This result may reflect the unmasking of a more aggressive lesion in those with underlying IDC and help identify patients with a higher likelihood of the presence of IDC at surgery. Although this study is small, it suggests that risk-stratifying patients with DCIS based on lesion and parenchymal imaging features associated with treatment response may aid in tailoring therapy for DCIS. We are testing this prospectively in an active surveillance cohort. Table 1. Incidence of IDC at surgery depending on image features (n= 34)Improvement of lesion in MRINo Improvement of lesion in MRIP-value (Fisher’s Exact Test)& No Reduction in BPE& Reduction in BPE& No Reduction in BPE& Reduction in BPEIncidence of IDC at surgery (n)0204Incidence of Not IDC at surgery (n)121024%IDC at surgery when assessing lesion only (%)9.1%40%0.048*%IDC at surgery when assessing lesion AND BPE (%)0%16.7%0%50%0.032*%IDC at surgery when assessing lesion AND BPE (%)8.3%50%0.018* Citation Format: Paul Kim, Heather I. Greenwood, Rita I. Freimanis, Gillian L Hirst, Megan Fischer-Colbrie, Jessica Gibbs, Nola M Hylton, Christina Yau, Eun-Sil Shelley Hwang, Laura J. Esserman, Rita A Mukhtar. Improved early stratification of invasive cancer risk using MRI in a ductal carcinoma in-situ short-term active surveillance cohort treated with neoadjuvant endocrine therapy [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 P6-16-06.

Background: Previous studies have independently validated the prognostic relevance of residual cancer burden (RCB) after neoadjuvant chemotherapy. We used results from several independent cohorts in a pooled patient-level analysis to evaluate the relationship of RCB with long-term prognosis across different phenotypic subtypes of breast cancer, to assess generalisability in a broad range of practice settings. Methods: In this pooled analysis, 12 institutes and trials in Europe and the USA were identified by personal communications with site investigators. We obtained participant-level RCB results, and data on clinical and pathological stage, tumour subtype and grade, and treatment and follow-up in November, 2019, from patients (aged ≥18 years) with primary stage I–III breast cancer treated with neoadjuvant chemotherapy followed by surgery. We assessed the association between the continuous RCB score and the primary study outcome, event-free survival, using mixed-effects Cox models with the incorporation of random RCB and cohort effects to account for between-study heterogeneity, and stratification to account for differences in baseline hazard across cancer subtypes defined by hormone receptor status and HER2 status. The association was further evaluated within each breast cancer subtype in multivariable analyses incorporating random RCB and cohort effects and adjustments for age and pretreatment clinical T category, nodal status, and tumour grade. Kaplan-Meier estimates of event-free survival at 3, 5, and 10 years were computed for each RCB class within each subtype. Findings: We analysed participant-level data from 5161 patients treated with neoadjuvant chemotherapy between Sept 12, 1994, and Feb 11, 2019. Median age was 49 years (IQR 20–80). 1164 event-free survival events occurred during follow-up (median follow-up 56 months [IQR 0–186]). RCB score was prognostic within each breast cancer subtype, with higher RCB score significantly associated with worse event-free survival. The univariable hazard ratio (HR) associated with one unit increase in RCB ranged from 1·55 (95% CI 1·41–1·71) for hormone receptor-positive, HER2-negative patients to 2·16 (1·79–2·61) for the hormone receptor-negative, HER2-positive group (with or without HER2-targeted therapy; p

Background: In previous work we leveraged the I-SPY2 trial to create treatment response predictive subtypes (RPS) incorporating tumor biology beyond clinical HR/HER2, to better predict drug responses in an expanded treatment landscape that includes platinum agents, dual HER2-targeting regimens and immunotherapy [1]. We showed that best performing schemas incorporate Immune, DRD and HER2/Luminal phenotypes, and that treatment allocation based on these would increase the overall pCR rate to 63% from 51% using HR/HER2-based treatment selection. The RPS schema has been selected for prospective evaluation in I-SPY2. Using the RPS, one would prioritize platinum-based therapy for HER2-/Immune-/DRD+, immunotherapy for HER2-/Immune+, and dual-anti-HER2 for HER2+ that are not luminal. HER2+/Luminal patients have low response rates to dual-anti-HER2 therapy but may respond better to anti-AKT. However, there is still a considerable ‘biomarker-negative’ group of resistant cancers (HER2-/Immune-/DRD-) with very low pCR rates to all tested agents, that require a new therapeutic approach. Here we characterize the protein signaling architecture of these tumors to identify new target candidates. Methods: 987 I-SPY 2 patients from 10 arms of the trial were considered for this analysis. All have gene expression, pCR and RPS; 944 have distant recurrence free survival (DRFS) data; and 736 have reverse phase protein array (RPPA) data from laser capture microdissected tumor epithelium. These data – known collectively as the I-SPY2-990 mRNA/RPPA Data Resource - were recently made public on NCBI’s Gene Expression Omnibus [GEO: GSE196096]. We focus on HER2-/Immune-/DRD- tumors, applying Wilcoxon and t-tests to identify phosphoproteins that differ between HR+HER2-/Immune-/DRD- and other HR+HER2- tumors; and between TN/Immune-/DRD- and other TNs. The Benjamini-Hochberg (BH) method is used to adjust p-values for multiple hypothesis testing. In addition, the Kaplan-Meier method is used to estimate DRFS. Results: 201/736 I-SPY 2 patients with RPPA data are classified HER2-/Immune-/DRD- (HR+HER2-: n=138; TN: n=63). Of these, 8.5% (17/201) achieved pCR. Non-responding HER2-/Immune-DRD- had worse outcomes than responders (~75% vs. ~95% DRFS at 5 years). 60/139 phospho-proteins differ significantly between HR+HER2-/Immune-/DRD- and other HR+HER2- tumors (n=122). These tumors are relatively ‘cold’, in that 90% (54/60) of the phosphoprotein activities characterizing this group are at lower levels than in the overall HR+HER2- population; including immune (e.g. pPDL1, pJAK/STAT) and proliferation (e.g., Ki67, CyclinB1, pAURK) endpoints. Phosphoproteins showing higher levels in this subset include ERBB2 (BH p=1.7E-06), Cyclin D1 (BH p=1.4E-05), pAR (BH p=1.4E-05), and ER (BH p=3E-04). Within the TN subset, only 3/139 phospho-proteins differed significantly between TN/Immune-/DRD- and other TN tumors (n=189). These were all immune-related (pPDL1, pSTAT1, and HLA DR), with lower expression in the TN/Immune-/DRD- group. Conclusion: HR+HER2- and TN patients who are Immune-Low and DRD-Low have very low pCR rates to all tested therapeutics in I-SPY2 including standard chemotherapy, platinum, and immunotherapy. Senolytics (possibly targeting Cyclin D1), HER2low agents, and AR modulators may overcome resistance in HR+HER2-/Immune-/DRD-, whereas an immune activator beyond checkpoint inhibition is suggested for TN/Immune-/DRD- patients. [1] Wolf et. al., Redefining Breast Cancer Subtypes to Guide Treatment Prioritization and Maximize Response: Predictive Biomarkers across 10 Cancer Therapies. Cancer Cell 2022 Citation Format: Denise M. Wolf, Christina Yau, Julia Wulfkuhle, Rosa I. Gallagher, Lamorna A. Brown Swigart, Gillian L. Hirst, Jean-Philippe Coppe, Mark Jesus M. Magbanua, Rosalyn Sayaman, I-SPY2 Investigators, Laura Sit, Nola M. Hylton, Angela DeMichele, Donald A. Berry, Lajos Pusztai, Douglas Yee, Laura J. Esserman, Emanuel F. Petricoin, Laura Van ’t Veer. PD5-04 Characterizing the HER2-/Immune-/DNA repair (DRD-) response predictive breast cancer subtype: the hunt for new protein targets in a high-needs population with low response to all I-SPY2 agents [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr PD5-04.

Background: The detection of circulating tumor DNA (ctDNA) may serve as an early predictor of response and recurrence. In this study, we used a tumor-informed ctDNA test to monitor clinical outcomes in patients with high-risk hormone receptor-positive HER2-negative (HR+HER2-) tumors who received neoadjuvant chemotherapy (NAC) on the I-SPY 2 trial (NCT01042379). Methods: We collected blood samples at pretreatment, during (at 3 and 12 weeks after initiation of paclitaxel-based treatment with or without an investigational drug), after NAC prior to surgery, 4 weeks after surgery, and annually until clinical diagnosis of recurrence. Cell-free DNA was isolated from plasma (N=329 samples) and ctDNA was detected using a personalized, tumor-informed multiplex polymerase chain reaction next generation sequencing-based test (SignateraTM). All patients were at high risk for recurrence by MammaPrint. The response endpoints were pathologic complete response (pCR) and residual cancer burden (RCB), and the survival endpoint was event-free survival (EFS). Results: This analysis included 66 patients with HR+HER2- breast cancer who had blood samples collected before, during, after NAC and had at least one blood sample after surgery with sufficient plasma for analysis. 57.1% (32/56) had grade III disease; 72.4% (42/58) were node-positive; 36.2% (21/58) had T3/T4 disease; and 33.3% (22/66) were MammaPrint High 2. The percent ctDNA positivity rates at pretreatment, after NAC prior to surgery, and 4 weeks after surgery were 79.7% (47/59), 6.5% (4/62), and 2% (1/50), respectively. Significantly higher ctDNA positivity rates at pretreatment were observed in patients with larger tumors (95% in T3/T4 vs. 69% in T1/T2, Fisher’s exact p=0.0387), higher grade tumors (94% in Grade III vs. 67% in Grade I/II, p=0.0147) and by MammaPrint score (100% in High 2 vs. 71% in High 1, p=0.0052). In this high-risk HR+/HER2- cohort, 10/66 (15.2%) achieved pCR/RCB 0, who were all ctDNA-negative at surgery. 56/66 (84.8%) had no-PCR, with RCB I (limited residual cancer), II (moderate) and III (extensive) in 7 (10.6%), 31 (47.0%) and 18 (27.3%), respectively. ctDNA-positivity after paclitaxel-based treatment was significantly associated with RCB II/III status (Fisher’s exact p=0.01). All patients in this cohort with persistent ctDNA subsequently had RCB II or III at surgery. 47 patients had paired samples collected after NAC prior to surgery and at 4 weeks after surgery. Of the 47, 91.5% (43/47) were ctDNA-negative at both time points and 8.5% (4/47) were discordant; 1 was ctDNA-negative and later tested ctDNA-positive, while 3 were ctDNA-positive and later tested ctDNA-negative. 61/66 patients had EFS data with a median of 1.6 years of follow up (range: 0.6 to 5.6). 5 tested ctDNA-positive in at least one time point after surgery. Of these, 2 experienced a recurrence (one local relapse and one distant metastasis) and both tested positive at the time of recurrence. For the patient who developed a distant recurrence it was the only blood sample available at a follow-up time point; for the patient who developed a local recurrence, blood from two earlier follow-up time points had tested negative. To date, no recurrences have been observed in those whose test(s) after surgery were negative for ctDNA. Conclusions: The persistence of ctDNA during neoadjuvant therapy is associated with the extent of residual disease in a cohort of patients with HR+HER2- breast cancer in the I-SPY 2 trial and thus may be useful in identifying patients who are not having an optimal response to therapy. I-SPY 2.2 will test whether ctDNA has utility in redirecting therapy to improve surgical outcome and subsequent prognosis. Citation Format: Mark Jesus M. Magbanua, Hope Rugo, Lamorna A. Brown Swigart, Ziad Ahmed, Gillian L. Hirst, Denise M. Wolf, Ruixiao Lu, Ekaterina Kalashnikova, Derrick Renner, Angel Rodriguez, Minetta C. Liu, Christina Yau, Laura J. Esserman, Laura Van ’t Veer, Angela DeMichele. Monitoring for response and recurrence in neoadjuvant-treated hormone receptor-positive HER2-negative breast cancer by personalized circulating tumor DNA testing [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P5-05-05.

I-SPY2 is an adaptively randomized phase 2 clinical trial evaluating novel agents in combination with standard-of-care paclitaxel followed by doxorubicin and cyclophosphamide in the neoadjuvant treatment of breast cancer. Ganitumab is a monoclonal antibody designed to bind and inhibit function of the type I insulin-like growth factor receptor (IGF-1R). Ganitumab was tested in combination with metformin and paclitaxel (PGM) followed by AC compared to standard-of-care alone. While pathologic complete response (pCR) rates were numerically higher in the PGM treatment arm for hormone receptor-negative, HER2-negative breast cancer (32% versus 21%), this small increase did not meet I-SPY’s prespecified threshold for graduation. PGM was associated with increased hyperglycemia and elevated hemoglobin A1c (HbA1c), despite the use of metformin in combination with ganitumab. We evaluated several putative predictive biomarkers of ganitumab response (e.g., IGF-1 ligand score, IGF-1R signature, IGFBP5 expression, baseline HbA1c). None were specific predictors of response to PGM, although several signatures were associated with pCR in both arms. Any further development of anti-IGF-1R therapy will require better control of anti-IGF-1R drug-induced hyperglycemia and the development of more predictive biomarkers.

Introduction: Standard treatment for ductal carcinoma in situ (DCIS) involves surgical excision with radiation and often endocrine therapy. However, not all DCIS progresses to invasive ductal carcinoma (IDC); thus, surgical intervention may constitute overtreatment for DCIS that has low risk for progressing to IDC. A period of active surveillance (AS) with magnetic resonance imaging (MRI) monitoring may offer the opportunity to stratify lesions with high and low risk for invasion and to avoid overtreatment of DCIS. The purpose of this study was to characterize the outcomes of a cohort of women who elected to go on AS to avoid surgical intervention and to identify whether clinical and imaging features would identify patients who should convert to operative management. Methods: The clinicopathologic variables and outcomes of patients with DCIS who prospectively enrolled in MRI monitoring studies between 2002 and 2019 were retrospectively analyzed with IRB approval. We included 64 cases among 63 women who declined standard operative management for DCIS and had at least two breast MRIs. Clinicopathologic data and physician recommendations regarding continuing surveillance versus converting to operative management were recorded from the medical record. Those who had surgical excision showing IDC were considered to have progressed; those with only DCIS at excision or no operative intervention were considered to have stable disease. Results: Women in the cohort were an average of 53.6 years (29.8 - 78.9) old, and nearly all cases of DCIS with estrogen receptor (ER) status were ER+ (98.3%). Of the 64 cases in the cohort, 57 received endocrine therapy (89.1%). Average length of time on AS was 2.7 years (.2 – 11.9) with a median of 3 (2 – 18) MRIs performed and mean follow-up time 5.6 years (0.9 – 15.3). A total of 31 cases (48.4%) eventually had surgical excision while 33 (51.6%) remained on AS. There were 17 cases with IDC at surgery (26.6%). The IDC was an average of 1.5 cm (0.1 – 9.0) and most commonly ER + (88.2%), HER2 + (53.3%), grade 2 (58.9%), and node negative (82.4%). Only 7 women did not take endocrine therapy, but 3 of those women had IDC (42.9%). In 15 of the 17 cases with IDC (88.2%), the physician noted concern for progression in their clinic note and recommended surgical excision. This occurred a mean of 1.9 years (0.2 – 6.5) from the start of AS, with 47%, 67%, and 87% of cases identified within 1, 2 and 3 years from the start of AS. Suspicion of progression was based on an increase in lesion size or prominence on MRI and/or increase in calcifications on mammography. Of those that were identified as good candidates to continue AS with no concern for progression (n = 49), 16 chose to undergo surgical excision (32.7%) and 2 had IDC (4.1%). Conclusion: After over a decade of following women who seek alternatives to surgery for DCIS, we have identified clinicopathologic and imaging features that discriminate good candidates for AS and endocrine risk reducing therapy from those best treated with surgical excision. In our cohort of mostly ER+ patients receiving endocrine therapy on AS, over half of the cohort (51.6%) avoided surgical intervention. Her2 status, Oncotype DCIS, and Mammaprint scores of IDC is in process and will be presented. Our data support the study of AS as a method to stratify the risk of IDC and avoid overtreatment. We will present a personalized AS algorithm (based on biology and imaging) that we intend to prospectively test in the ATHENA network and NCI funded MCL consortium. Table 1: Cohort CharacteristicsFull Cohort (n=64)No evidence of IDC (n=47)IDC at surgery (n=17)Age at Diagnosis (years)53.6 (29.8 - 78.9)52.9 (29.8 - 74.5)55.5 (41.9 - 78.9)Time on AS (years)2.7 (.2 - 11.9)2.8 (.2 - 11.9)2.2 (.3 -5.9)Follow-Up (years)5.6 (0.9 - 15.3)Menopausal StatusPremenopausal26 (40.6%)22 (46.8%)4 (23.5%)Postmenopausal35 (54.7%)24 (51.1%)11 (64.7%)Unknown3 (4.7%)1 (2.1%)2 (11.8%)Breast CompositionFatty4 (6.3%)3 (6.4%)1 (5.9%)Scattered14 (21.9%)9 (19.1%)5 (29.4%)Heterogeneous27 (42.2%)19 (40.4%)8 (47.1%)Extreme17 (26.5%)14 (29.8%)3 (17.6%)Unknown2 (3.1%)2 (4.3%)0 (0.0%)ER StatusPositive57 (89.1%)41 (87.2%)16 (94.1%)Negative1 (1.6%)0 (0.0%)1 (5.9%)Unknown6 (9.3%)6 (12.8%)0 (0.0%)PR StatusPositive50 (78.1%)36 (76.6%)14 (82.3%)Negative5 (7.8%)3 (6.4%)2 (11.8%)Unknown9 (14.1%)8 (17.0%)1 (5.9%)GradeHigh20 (31.3%)15 (31.8%)5 (29.4%)Intermediate32 (50.0%)21 (44.6%)11 (64.7%)Low10 (15.6%)9 (19.1%)1 (5.9%)Unknown2 (3.1%)2 (28.5%)0 (0.0%Hormone TherapyYes57 (89.1%)43 (91.5%)14 (82.4%)No7 (10.9%)4 (8.5%)3 (17.6%) Citation Format: Case Brabham, Rita Mukhtar, April Liang, Paul Kim, Gillian Hirst, Amrita Basu, Heather Greenwood, Rita Freimanis, Alexander Borowsky, Shelley Hwang, Rick Baehner, Gregor Krings, Nola Hylton, Laura Esserman. Active surveillance for DCIS: Clinical outcomes at 5.6 years mean follow-up [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 PS1-03.

HSP90 inhibitors destabilize oncoproteins associated with cell cycle, angiogenesis, RAS-MAPK activity, histone modification, kinases and growth factors. We evaluated the HSP90-inhibitor ganetespib in combination with standard chemotherapy in patients with high-risk early-stage breast cancer. I-SPY2 is a multicenter, phase II adaptively randomized neoadjuvant (NAC) clinical trial enrolling patients with stage II-III breast cancer with tumors 2.5 cm or larger on the basis of hormone receptors (HR), HER2 and Mammaprint status. Multiple novel investigational agents plus standard chemotherapy are evaluated in parallel for the primary endpoint of pathologic complete response (pCR). Patients with HER2-negative breast cancer were eligible for randomization to ganetespib from October 2014 to October 2015. Of 233 women included in the final analysis, 140 were randomized to the standard NAC control; 93 were randomized to receive 150 mg/m2 ganetespib every 3 weeks with weekly paclitaxel over 12 weeks, followed by AC. Arms were balanced for hormone receptor status (51–52% HR-positive). Ganetespib did not graduate in any of the biomarker signatures studied before reaching maximum enrollment. Final estimated pCR rates were 26% vs. 18% HER2-negative, 38% vs. 22% HR-negative/HER2-negative, and 15% vs. 14% HR-positive/HER2-negative for ganetespib vs control, respectively. The predicted probability of success in phase 3 testing was 47% HER2-negative, 72% HR-negative/HER2-negative, and 19% HR-positive/HER2-negative. Ganetespib added to standard therapy is unlikely to yield substantially higher pCR rates in HER2-negative breast cancer compared to standard NAC, and neither HSP90 pathway nor replicative stress expression markers predicted response. HSP90 inhibitors remain of limited clinical interest in breast cancer, potentially in other clinical settings such as HER2-positive disease or in combination with anti-PD1 neoadjuvant chemotherapy in triple negative breast cancer.Trial registration: www.clinicaltrials.gov/ct2/show/NCT01042379

Background: Patients achieving a pathologic complete response (pCR) following neoadjuvant therapy have significantly improved event-free survival relative to those who do not; and pCR is an FDA-accepted endpoint to support accelerated approval of novel agents/combinations in the neoadjuvant treatment of high risk early stage breast cancer. Previous studies have shown that recurrence risk increased with increasing burden of residual disease (as assessed by the RCB index). As well, these studies suggest that patients with minimum residual disease (RCB-I class) also have favorable outcomes (comparable to those achieving a pCR) within high risk tumor subtypes. In this study, we assess whether integrating RCB with MRI functional tumor volume (FTV), which in itself is prognostic, can improve prediction of distant recurrence free survival (DRFS); and identify a subset of patients with minimal residual disease with comparable DRFS as those who achieved a pCR. Imaging tools can then be used to identify the subset that will do well early and guide the timing of surgical therapy. Method: We performed a pooled analysis of 596 patients from the I-SPY2 TRIAL with RCB, pre-surgical MRI FTV data and known follow-up (median 2.5 years). We first assessed whether FTV predicts residual disease (pCR or pCR/RCB-I) using ROC analysis. We applied a power transformation to normalize the pre-surgical FTV distribution; and assessed its association with DRFS using a bi-variate Cox proportional hazard model adjusting for HR/HER2 subtype. We also fitted a bivariate Cox model of RCB index adjusting for subtype; and assessed whether adding pre-surgical FTV to this model further improves association with DRFS using a likelihood ratio (LR) test. For the Cox modeling, penalized splines approximation of the transformed FTV and RCB index with 2 degrees of freedom was used to allow for non-linear effects of FTV and RCB on DRFS. Result: Pre-surgical MRI FTV is significantly associated with DRFS (Wald p Conclusion: Pre-surgical MRI FTV is effective at predicting minimal residual disease (RCB0/I) in the I-SPY 2 TRIAL. Despite the association between FTV and RCB, FTV appears to provide independent added prognostic value (to RCB and subtype), suggesting that integrating MRI volume measures and RCB into a composite predictor may improve DRFS prediction. Citation Format: Hylton NM, Symmans WF, Yau C, Li W, Hatzis C, Isaacs C, Albain KS, Chen Y-Y, Krings G, Wei S, Harada S, Datnow B, Fadare O, Klein M, Pambuccian S, Chen B, Adamson K, Sams S, Mhawech-Fauceglia P, Magliocco A, Feldman M, Rendi M, Sattar H, Zeck J, Ocal I, Tawfik O, Grasso LeBeau L, Sahoo S, Vinh T, Yang S, Adams A, Chien AJ, Ferero-Torres A, Stringer-Reasor E, Wallace A, Boughey JC, Ellis ED, Elias AD, Lang JE, Lu J, Han HS, Clark AS, Korde L, Nanda R, Northfelt DW, Khan QJ, Viscusi RK, Euhus DM, Edmiston KK, Chui SY, Kemmer K, Wood WC, Park JW, Liu MC, Olopade O, Tripathy D, Moulder SL, Rugo HS, Schwab R, Lo S, Helsten T, Beckwith H, Haugen PK, van't Veer LJ, Perlmutter J, Melisko ME, Wilson A, Peterson G, Asare AL, Buxton MB, Paoloni M, Clennell JL, Hirst GL, Singhrao R, Steeg K, Matthews JB, Sanil A, Berry SM, Abe H, Wolverton D, Crane EP, Ward KA, Nelson M, Niell BL, Oh K, Brandt KR, Bang DH, Ojeda-Fournier H, Eghtedari M, Sheth PA, Bernreuter WK, Umphrey H, Rosen MA, Dogan B, Yang W, Joe B, I-SPY 2 TRIAL Consortium, Yee D, Pusztai L, DeMichele A, Asare SM, Berry DA, Esserman LJ. Refining neoadjuvant predictors of three year distant metastasis free survival: Integrating volume change as measured by MRI with residual cancer burden [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-07-03.

Introduction: Diagnostic metastatic staging imaging (SI) for asymptomatic stage I-II patients (pts) is not routinely recommended, but is warranted in stage II-III pts with high risk biological subtypes, where previous trials have shown up to a 15% rate of de novo metastatic disease. NCCN guidelines endorse CT CAP and bone scan (STD) for stage III pts, but not PET/CT, and PET/CT is not covered in most parts of the country. We present data on the performance and value of PET/CT. Methods: Data were available for 799 high risk clinical stage II-III pts screened for I-SPY2 at UCSF, Uminn, UAB, and Georgetown. Of these, 564 pts ranging in age from 25-81 (median = 48) had complete records that were retrospectively reviewed for SI and potential false positives (FP), defined as incidental findings on SI proven benign by subsequent workup. Economic evaluation was conducted from the payer perspective using the mean national 2018 Medicare Physician Fee Schedule and representative costs from the UCSF billing department. The incremental cost effectiveness ratio (ICER) measured the cost of using PET/CT per percent patient (pt) who avoided a FP. Results: The rate of de novo metastatic disease was 4.8% (38/799), range 3.6-6.4%. Of the 564 pts with complete records, diagnostic SI varied significantly among the four sites (p < 0.0001). STD was used for most pts at UAB (92.8%, 141/152) and Georgetown (85.7%, 54/63), while PET/CT was used for most pts at UCSF (86.6%, 226/261) and Uminn (63.6%, 56/88). Chest X-ray was used for 29.5% (26/88) at Uminn. There were significantly more pts with FP in the group that received STD (22.1%, 51/231) vs. PET/CT (11.1%, 33/298) (p < 0.05). Mean time between incidental finding on SI to determination of FP was 10.8 days. When controlling for institution, mean time from cancer diagnosis to initiation of neoadjuvant chemotherapy was significantly different between STD (44.3 days) and PET/CT (37.5 days) groups (p < 0.05). When aggregating the four sites using mean costs from the 2018 Medicare Physician Fee Schedule, the mean cost/pt was $1132 for STD vs. $1477 for PET/CT. The mean increase in price from baseline SI costs due to FP workup was $216 (23.6%) for STD vs. $65 (4.6%) for PET/CT. The ICER was $31 per percent pt who avoided a FP. When analyzing UCSF pts alone using representative reimbursements from Medicare, the mean cost/pt was $1236 for STD vs. $1081 for PET/CT; using representative reimbursements from Anthem Blue Cross, the mean cost/pt was $3080 for STD vs. $1662 for PET/CT. The ICERs were -$10 and -$95 per percent pt who avoided a FP, respectively. Conclusion: As compared to STD metastatic staging workup, PET/CT added value by decreasing FP two-fold. This reduced direct costs of FP workup procedures that took a mean time of 10.8 days to resolve. PET/CT also accelerated treatment start. Reducing the chance of FP workup for metastatic disease is of enormous value to pts. Our data establish the value of PET/CT for staging in our high risk clinical stage II-III trial population and highlight the need for alignment between hospital pricing strategies and payer coverage policies in order to deliver high value care to pts. Citation Format: Hyland CJ, Varghese F, Yau C, Beckwith H, Khoury K, Varnado W, Hirst G, Chien J, Yee D, Isaacs C, Forero-Torres A, Esserman L, Melisko M, I-SPY2 Consortium. The use of 18F-FDG PET/CT as an initial staging procedure for stage II-III breast cancer reduces false positives, costs, and time to treatment: A multicenter value analysis in the I-SPY2 trial [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P5-15-01.

Background: Expression-based signatures have been shown to predict neoadjuvant therapy response; but further studies are needed to deconvolve the contribution of different immune cell types. The I-SPY 2 TRIAL is a standing neoadjuvant platform trial which evaluates experimental agents/combinations when added to standard chemotherapy. In this study, we compared published T/B cell-related signatures at 3 different levels of resolution as predictors of response in the I-SPY 2 TRIAL: (1) a combined T/B-cell co-expression module, correlated with general lymphocytic infiltrate, (2) individual T-cell and a B-cell specific signatures derived from purified immune cells and refined using tumor expression, and (3) 9 T cell subpopulation-specific signatures, including a CD8+ T resident memory phenotype (TRM) and a CD8+ T effector memory subset (TEM), generated from microdroplet-based single cell (sc) RNA sequencing of over 6000 tumor associated CD3+ T cells. Methods: Expression data from 989 I-SPY 2 patients randomized to one of 9 possible experimental arms or the standard chemotherapy control were available for analysis. Pre-treatment biopsies were assayed using Agilent gene expression arrays. All I-SPY 2 biomarker analyses follow a pre-specified analysis plan. We used logistic modeling to assess each signature as a predictor of pCR within each arm (likelihood ratio test p Results: In the population as a whole, immune signatures predict response across multiple classes of agents (8/10 arms), including the checkpoint inhibitor Pembrolizumab (Pembro). However, the cell-type and subpopulation-specific signatures most predictive of response vary by subtype and agent. For instance, the T/B-cell co-expression module associates with response to Pembro and the Angiopoetin-1/-2 inhibitor AMG-386 in both HR-HER2- and HR+ERHHER2- subtypes. However, in the HR-HER2- subtype, the T-cell signature and the sc-derived CD8-TRM signature are most predictive; whereas in the HR+HER2- subtype, it is the B-cell, CD8-TRM and a novel CD4 signature that are most strongly associated with response. In the HER2+ subtype, the T/B-cell module and B-cell signature is associated with response to the AKT-inhibitor MK2206. Interestingly, among the sc-derived signatures, it is the CD8-TEM and multiple CD4 population-specific signatures, rather than CD8-TRM, that associate with response. Conclusion: Our exploratory study suggests that immune signatures are associated with response to multiple I-SPY 2 experimental agents and implicates different immune cell types as response-predictive within breast cancer subtypes. Single cell sequencing derived population specific signatures may help further de-convolute how different immune cell types contribute to therapy responsiveness. Citation Format: Yau C, Wolf DM, Campbell M, Savas P, Lin S, Brown-Swigart L, Hirst G, Asare S, Zhu Z, I-SPY 2 TRIAL Consortium, Loi S, DeMichele A, Yee D, Berry D, Esserman L, van 't Veer L. Expression-based immune signatures as predictors of neoadjuvant targeted-/chemo-therapy response: Experience from the I-SPY 2 TRIAL of ˜1000 patients across 10 therapies [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-10-06.

Background: The explosion in new treatment options targeting immune checkpoints, HER signaling, DNA repair deficiency, AKT, and other pathways calls for updated breast cancer subtypes beyond HR and HER2 status to predict which patients will respond to which treatments. Here we leverage the I-SPY 2 TRIAL biomarker program over the past 8 years across 10 treatment arms to elucidate a minimal set of biomarkers that may improve response prediction in a modern treatment context, and to investigate which new patient phenotypes are identified by these response-predictive biomarkers. Methods: 986 patients were considered in this analysis. Treatments included paclitaxel alone (or with trastuzumab (H) in HER2+) or combined with investigational agents: veliparib/carboplatin (VC); neratinib; MK2206; ganitumab; ganetespib; AMG386; TDM1/pertuzumab (P); H/P; and pembrolizumab (Pembro). 24 prospectively defined, mechanism-of-action and pathway-based expression and phospho-protein signatures/biomarkers assayed from pre-treatment biopsies were previously found to be predictive in a particular agent/arm in pre-specified analysis. Here we evaluate these biomarkers in all patients. We assessed association between each biomarker and response in the population as a whole and within each arm and HR/HER2 subtype using a logistic model. To identify optimal dichotomizing thresholds for select biomarkers, 2-fold cross-validation was repeated 500 times. Our analysis is exploratory and does not adjust for multiplicities. Results: Our initial set of 24 predictive biomarkers reflects DNA repair deficiency (n=2), immune activation (n=7), ER signaling (n=2), HER2 signaling (n=4), proliferation (n=2), phospho-activation of AKT/mTOR (n=2), and ANG/TIE2 (n=1) pathways, among others. Biomarkers reflecting similar biology are correlated and cluster together. We make use of this correlation structure to reduce the dimensionality of the biomarker set to five predictive signals: proliferation, DNA repair deficiency (DRD), immune-engaged (Immune+), luminal/ER (lum), and HER2-activated. These biomarkers, when dichotomized, identify patient groups with differential predicted sensitivities to I-SPY 2 agents and are present at different proportions within receptor subtypes. For instance, in the HER2- subset, Immune+/DRD+ patients are predicted sensitive to both VC and Pembro, and account for 39% of TN, but only 12% of HR+HER2-. On the other end of the spectrum, only 17% of TN are Immune-/DRD-, compared to the majority (56%) of HR+HER2-. There are also subsets of patients positive for only one marker. For the HER2+ subset, 67% are HER2-activated+, and 25% lum+; of these HER2-activated+ patients are more likely to be Immune+ (44%), vs 23% in lum+. HER2-activated+/Immune+ patients have higher predicted sensitivity to HER2-targeted agents than lum+ or Immune- patients. In all, these molecular phenotypes predict sensitivity to one or more I-SPY 2 investigational agents for 75% of the ˜ 1000 patients. Conclusion: Molecular phenotypes reflecting proliferation, immune engagement, HER2-activation, luminal/ER-signaling, and DNA repair deficiency may provide a roadmap to guide treatment prioritization for emerging therapeutics. Citation Format: Wolf DM, Yau C, Wulfkuhle J, Petricoin E, Campbell M, Brown-Swigart L, Hirst G, Asare S, Zhu Z, Lee EP, Delson A, Pohlmann P, I-SPY 2 TRIAL Consortium, Hylton N, Liu MC, Symmans F, DeMichele A, Yee D, Berry D, Esserman L, van 't Veer L. Identifying breast cancer molecular phenotypes to predict response in a modern treatment landscape: Lessons from ˜1000 patients across 10 arms of the I-SPY 2 TRIAL [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-10-02.

ObjectivesIn this paper, we discuss leveraging cloud-based platforms to collect, visualize, analyze, and share data in the context of a clinical trial. Our cloud-based infrastructure, Patient Repository of Biomolecular Entities (PRoBE), has given us the opportunity for uniform data structure, more efficient analysis of valuable data, and increased collaboration between researchers.Materials and MethodsWe utilize a multi-cloud platform to manage and analyze data generated from the clinical Investigation of Serial Studies to Predict Your Therapeutic Response with Imaging And moLecular Analysis 2 (I-SPY 2 TRIAL). A collaboration with the Institute for Systems Biology Cancer Gateway in the Cloud has additionally given us access to public genomic databases. Applications to I-SPY 2 data have been built using R Shiny, while leveraging Google's BigQuery tables and SQL commands for data mining.ResultsWe highlight the implementation of PRoBE in several unique case studies including prediction of biomarkers associated with clinical response, access to the Pan-Cancer Atlas, and integrating pathology images within the cloud. Our data integration pipelines, documentation, and all codebase will be placed in a Github repository.Discussion and conclusionWe are hoping to develop risk stratification diagnostics by integrating additional molecular, magnetic resonance imaging, and pathology markers into PRoBE to better predict drug response. A robust cloud infrastructure and tool set can help integrate these large datasets to make valuable predictions of response to multiple agents. For that reason, we are continuously improving PRoBE to advance the way data is stored, accessed, and analyzed in the I-SPY 2 clinical trial.

We investigated whether serial measurements of circulating tumor DNA (ctDNA) and functional tumor volume (FTV) by magnetic resonance imaging (MRI) can be combined to improve prediction of pathologic complete response (pCR) and estimation of recurrence risk in early breast cancer patients treated with neoadjuvant chemotherapy (NAC). We examined correlations between ctDNA and FTV, evaluated the additive value of ctDNA to FTV-based predictors of pCR using area under the curve (AUC) analysis, and analyzed the impact of FTV and ctDNA on distant recurrence-free survival (DRFS) using Cox regressions. The levels of ctDNA (mean tumor molecules/mL plasma) were significantly correlated with FTV at all time points (p p p = 0.25). In contrast, ctDNA-positivity after NAC provided significant additive value to FTV in identifying patients with increased risk of metastatic recurrence and death (p = 0.004). In this pilot study, we demonstrate that ctDNA and FTV were correlated measures of tumor burden. Our preliminary findings based on a limited cohort suggest that ctDNA at surgery improves FTV as a predictor of metastatic recurrence and death. Validation in larger studies is warranted.

Background: We compared the predictive and prognostic value of ctDNA dynamics in high-risk hormone receptor-positive/HER2-negative (HR+/HER2-) and triple negative breast cancer (TNBC) receiving neoadjuvant chemotherapy (NAC) enrolled in the I-SPY 2 trial (NCT01042379). To our knowledge, this is the largest ctDNA study in breast cancer in the neoadjuvant setting. Methods: Blood samples were collected at pre-treatment (T0), during treatment (T1 at 3 weeks, and T2 at 12 weeks) and after NAC (T3 at 24 weeks) from 106 HR+/HER2- and 97 TNBC patients. Plasma samples (n=734) were analyzed using a personalized and tumor-informed mPCR NGS-based ctDNA test (SignateraTM). Patients, all high risk for recurrence by MammaPrint, received paclitaxel-based treatment +/- experimental therapy followed by anthracycline. The median follow-up was 3.0 years (0.5 to 6.5). The predictive and prognostic value of ctDNA dynamics and status at different timepoints were examined. Our analysis is exploratory and does not adjust for other biomarkers. Results: Pretreatment ctDNA positivity (Fisher p Conclusions: The predictive value of ctDNA for prediction of pCR and RCB differed between subtypes (HR+/HER2- vs. TNBC), while similar prognostic value was observed. In TNBC, early clearance of ctDNA at 3 weeks was a significant predictor of favorable response to NAC. Compared to patients who were ctDNA-positive after NAC, ctDNA-negative status in both subtypes was associated with improved DRFS even in patients with residual cancer (no pCR or RCB-II/III). These findings could inform on the design of future studies that seek to demonstrate the utility of ctDNA in the curative setting. Predictive and prognostic significance of ctDNA in early breast cancer in the neoadjuvant setting HR+HER2- (n=106) TNBC (n=97) Predictive value for prediction of pCR and RCB Fisher p-value Fisher p-value Early ctDNA clearance (between T0 and T1) and pCR 0.4521 Citation Format: Mark Jesus Mendoza Magbanua, Lamorna Brown Swigart, Derrick Renner, Svetlana Shchegrova, Gillian L. Hirst, Christina Yau, Denise M. Wolf, Hsin-Ta Wu, Ekaterina Kalashnikova, Amy L. Delson, A. Jo Chien, Debu Tripathy, Smita Asare, Raheleh Salari, Angel Rodriguez, Bernhard Zimmermann, Himanshu Sethi, Alexey Aleshin, Paul Billings, Rita Nanda, Hope S. Rugo, Laura J. Esserman, Minetta C. Liu, Angela DeMichele, Laura van 't Veer. Comparison of the predictive and prognostic significance of circulating tumor DNA in patients with high risk HER2-negative breast cancer receiving neoadjuvant chemotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr LB111.

Using pre-treatment gene expression, protein/phosphoprotein and clinical data from the I-SPY2 neoadjuvant platform trial (NCT01042379), we create alternative breast cancer subtypes incorporating tumor biology beyond clinical hormone-receptor (HR) and Human Epidermal Growth Factor Receptor-2 (HER2) status to better predict drug responses. We assess predictive performance of mechanism-of-action biomarkers from ~990 patients treated with 10 regimens targeting diverse biology. We explore >11 subtyping schemas and identify treatment-subtype pairs maximizing pathologic complete response (pCR) rate over the population. The best performing schemas incorporate Immune, DNA-repair and HER2/Luminal phenotypes. Subsequent treatment allocation increases overall pCR rate to 63% from 51% using HR/HER2-based treatment selection. pCR gains from reclassification and improved patient selection are highest in HR+ subsets (>15%). As new treatments are introduced, the subtyping schema determines the minimum response needed to show efficacy. This data platform provides an unprecedented resource and supports the usage of response-based subtypes to guide future treatment prioritization.

The combination of PD-L1 inhibitor durvalumab and PARP inhibitor olaparib added to standard paclitaxel neoadjuvant chemotherapy (durvalumab/olaparib/paclitaxel [DOP]) was investigated in the phase II I-SPY2 trial of stage II/III HER2-negative breast cancer. Seventy-three participants were randomized to DOP and 299 to standard of care (paclitaxel) control. DOP increased pathologic complete response (pCR) rates in all HER2-negative (20%-37%), hormone receptor (HR)-positive/HER2-negative (14%-28%), and triple-negative breast cancer (TNBC) (27%-47%). In HR-positive/HER2-negative cancers, MammaPrint ultra-high (MP2) cases benefited selectively from DOP (pCR 64% versus 22%), no benefit was seen in MP1 cancers (pCR 9% versus 10%). Overall, 12.3% of patients in the DOP arm experienced immune-related grade 3 adverse events versus 1.3% in control. Gene expression signatures associated with immune response were positively associated with pCR in both arms, while a mast cell signature was associated with non-pCR. DOP has superior efficacy over standard neoadjuvant chemotherapy in HER2-negative breast cancer, particularly in a highly sensitive subset of high-risk HR-positive/HER2-negative patients.

The AKT inhibitor MK2206 (M) was evaluated in I-SPY 2 and graduated in the HER2+, HR−, and HR− HER2+ signatures. We hypothesized that AKT signaling axis proteins/genes may specifically predict response to M and tested 26 phospho-proteins and 10 genes involved in AKT-mTOR-HER signaling; in addition, we tested 9 genes from a previous study in the metastatic setting. One hundred and fifty patients had gene expression data from pretreatment biopsies available for analysis (M: 94, control: 56) and 138 had protein data (M: 87, control: 51). Logistic modeling was used to assess biomarker performance in pre-specified analysis. In general, phospho-protein biomarkers of activity in the AKT-mTOR-HER pathway appeared more predictive of response to M than gene expression or total protein biomarkers in the same pathway; however, the nature of the predictive biomarkers differed in the HER2+ and TN groups. In the HER2+ subset, patients achieving a pCR in M had higher levels of multiple AKT kinase substrate phospho-proteins (e.g., pmTOR, pTSC2). In contrast, in the TN subset responding patients had lower levels of AKT pathway phospho-proteins, such as pAKT, pmTOR, and pTSC2. Pathway mutations did not appear to account for these associations. Additional exploratory whole-transcriptome analysis revealed immune signaling as strongly associated with response to M in the HER2+ subset. While our sample size is small, these results suggest that the measurement of particular AKT kinase substrate phospho-proteins could be predictive of MK2206 efficacy in both HER2+ and TN tumors and that immune signaling may play a role in response in HER2+ patients.

Background Systematic cancer screening has led to the increased detection of pre-malignant lesions (PMLs). The absence of reliable prognostic markers has led mostly to over treatment resulting in potentially unnecessary stress, or insufficient treatment and avoidable progression. Importantly, most mutational profiling studies have relied on PML synchronous to invasive cancer, or performed in patients without outcome information, hence limiting their utility for biomarker discovery. The limitations in comprehensive mutational profiling of PMLs are in large part due to the significant technical and methodological challenges: most PML specimens are small, fixed in formalin and paraffin embedded (FFPE) and lack matching normal DNA. Methods Using test DNA from a highly degraded FFPE specimen, multiple targeted sequencing approaches were evaluated, varying DNA input amount (3–200 ng), library preparation strategy (BE: Blunt-End, SS: Single-Strand, AT: A-Tailing) and target size (whole exome vs. cancer gene panel). Variants in high-input DNA from FFPE and mirrored frozen specimens were used for PML-specific variant calling training and testing, respectively. The resulting approach was applied to profile and compare multiple regions micro-dissected (mean area 5 mm2) from 3 breast ductal carcinoma in situ (DCIS). Results Using low-input FFPE DNA, BE and SS libraries resulted in 4.9 and 3.7 increase over AT libraries in the fraction of whole exome covered at 20x (BE:87%, SS:63%, AT:17%). Compared to high-confidence somatic mutations from frozen specimens, PML-specific variant filtering increased recall (BE:85%, SS:80%, AT:75%) and precision (BE:93%, SS:91%, AT:84%) to levels expected from sampling variation. Copy number alterations were consistent across all tested approaches and only impacted by the design of the capture probe-set. Applied to DNA extracted from 9 micro-dissected regions (8 PML, 1 normal epithelium), the approach achieved comparable performance, illustrated the data adequacy to identify candidate driver events (GATA3 mutations, ERBB2 or FGFR1 gains, TP53 loss) and measure intra-lesion genetic heterogeneity. Conclusion Alternate experimental and analytical strategies increased the accuracy of DNA sequencing from archived micro-dissected PML regions, supporting the deeper molecular characterization of early cancer lesions and achieving a critical milestone in the development of biology-informed prognostic markers and precision chemo-prevention strategies.

PURPOSEThe phosphatidylinositol 3-kinase/Akt/mammalian target of rapamycin is a key pathway of survival and therapeutic resistance in breast cancer. We evaluated the pan-Akt inhibitor MK-2206 in combination with standard therapy in patients with high-risk early-stage breast cancer.PATIENTS AND METHODSI-SPY 2 is a multicenter, phase II, open-label, adaptively randomized neoadjuvant platform trial that screens experimental therapies and efficiently identifies potential predictive biomarker signatures. Patients are categorized by human epidermal growth factor receptor 2 (HER2), hormone receptor (HR), and MammaPrint statuses in a 2 × 2 × 2 layout. Patients within each of these 8 biomarker subtypes are adaptively randomly assigned to one of several experimental therapies, including MK-2206, or control. Therapies are evaluated for 10 biomarker signatures, each of which is a combination of these subtypes. The primary end point is pathologic complete response (pCR). A therapy graduates with one or more of these signatures if and when it has an 85% Bayesian predictive probability of success in a hypothetical phase III trial, adjusting for biomarker covariates. Patients in the current report received standard taxane- and anthracycline-based neoadjuvant therapy without (control) or with oral MK-2206 135 mg/week.RESULTSMK-2206 graduated with 94 patients and 57 concurrently randomly assigned controls in 3 graduation signatures: HR-negative/HER2-positive, HR-negative, and HER2-positive. Respective Bayesian mean covariate-adjusted pCR rates and percentage probability that MK-2206 is superior to control were 0.48:0.29 (97%), 0.62:0.36 (99%), and 0.46:0.26 (94%). In exploratory analyses, MK-2206 evinced a numerical improvement in event-free survival in its graduating signatures. The most significant grade 3-4 toxicity was rash (14% maculopapular, 8.6% acneiform).CONCLUSIONThe Akt inhibitor MK-2206 combined with standard neoadjuvant therapy resulted in higher estimated pCR rates in HR-negative and HER2-positive breast cancer. Although MK-2206 is not being further developed at this time, this class of agents remains of clinical interest.

Pathologic complete response (pCR) to neoadjuvant chemotherapy (NAC) is strongly associated with favorable outcome. We examined the utility of serial circulating tumor DNA (ctDNA) testing for predicting pCR and risk of metastatic recurrence in 84 high-risk early breast cancer patients treated in the neoadjuvant I-SPY 2 TRIAL. Cell-free DNA (cfDNA) was isolated from 291 plasma samples collected at pretreatment (T0), 3 weeks after initiation of paclitaxel (T1), between paclitaxel and anthracycline regimens (T2), or prior to surgery (T3). A personalized ctDNA test was designed to detect 16 patient-specific mutations (from whole exome sequencing of pretreatment tumor) in cfDNA by ultra-deep sequencing. At T0, 61 of 84 (73%) patients were ctDNA-positive, which decreased over time (T1-35%; T2-14%; T3-9%). Patients who remained ctDNA-positive at T1 were significantly more likely to have residual disease after NAC (83% non-pCR) compared to those who cleared ctDNA (52% non-pCR; OR 4.33, P=0.012). After NAC, all patients who achieved pCR were ctDNA-negative (n=17, 100%). For those who did not achieve pCR (n=43), ctDNA-positive patients (14%) had significantly increased risk of metastatic recurrence (HR 10.4; 95% CI, 2.3–46.6); interestingly, patients who did not achieve pCR but were ctDNA-negative (86%) had excellent outcome, similar to those who achieved pCR (HR 1.4; 95% CI, 0.15–13.5). Lack of ctDNA clearance was a significant predictor of poor response and metastatic recurrence, while clearance was associated with improved survival regardless of pCR status. Personalized monitoring of ctDNA during NAC may aid in real-time assessment of treatment response and help fine-tune pCR as a surrogate endpoint of survival.

The combination of PD-L1-inhibitor durvalumab and PARP-inhibitor olaparib (DOP) in addition to standard neoadjuvant chemotherapy was investigated in the phase II I-SPY2 platform trial of stage II/III HER2-negative breast cancer. Seventy-three HER2-negative participants were randomized to DOP and 299 to standard of care control. DOP graduated in all subtypes, increasing pCR rates in all HER2-negative (22 to 37%), HR-positive/HER2-negative (14% to 28%), TNBC (27% to 47%). In HR-positive/HER2-negative cancers, pCR rate in MammaPrint ultra high (MP2) cases was considerably higher than MP1, 64% vs 22%. Overall,12.3% of patients in the experimental arm experienced immune-related grade 3 adverse events vs. 1.3% in control. Gene expression signatures associated with immune response were positively associated with pCR in both arms, while a mast cell signature was associated with non-pCR. DOP has potential benefits over standard neoadjuvant therapy in HER2-negative early breast cancer, particularly in a highly sensitive subset of high-risk HR-positive/HER2-negative patients.

Ionising radiation (IR) is a recognised carcinogen responsible for cancer development in patients previously treated using radiotherapy, and in individuals exposed as a result of accidents at nuclear energy plants. However, the mutational signatures induced by distinct types and doses of radiation are unknown. Here, we analyse the genetic architecture of mammary tumours, lymphomas and sarcomas induced by high (56Fe-ions) or low (gamma) energy radiation in mice carrying Trp53 loss of function alleles. In mammary tumours, high-energy radiation is associated with induction of focal structural variants, leading to genomic instability and Met amplification. Gamma-radiation is linked to large-scale structural variants and a point mutation signature associated with oxidative stress. The genomic architecture of carcinomas, sarcomas and lymphomas arising in the same animals are significantly different. Our study illustrates the complex interactions between radiation quality, germline Trp53 deficiency and tissue/cell of origin in shaping the genomic landscape of IR-induced tumours., Mutational signatures induced by ionising radiation remain largely unexplored. Here in TP53 mutant mice, the authors characterise the genomic landscape of tumours induced by high- and low-energy radiation.

Background: Pathological complete response (pCR) is accepted by FDA as a surrogate endpoint for accelerated approval of targeted agents in combination with chemotherapy based on better long-term outcomes compared to residual disease (Cortazar 2014). Methods: The multi-center, adaptively-randomized I-SPY2 platform trial uses pCR as the primary endpoint to identify investigational agents that will improve outcomes in women with stage 2/3 breast cancer with high risk of early recurrence, across all signatures, based on hormone receptor (HR), HER2, and 70-gene (MammaPrint) status. For patients with HR+ HER2- tumors, only 70-gene (Mammaprint) high-risk patients are enrolled. To date, 1200+ patients have been randomized to one of 14 arms: control (paclitaxel followed by AC); veliparib/carboplatin; neratinib; MK2206; trebananib; trastuzumab/pertuzumab; ado-trastuzumab emtansine/pertuzumab; pembrolizumabx4; ganitumab/metformin; ganetespib; PLX-3397. 7 agents graduated in at least one signature (> 85% probability of success in a 300-patient phase III confirmatory trial); 2 did not graduate; 1 stopped for toxicity, and 3 are enrolling (patritumab/trastuzumab, talazoparib/irinotecan, pembrolizumabx8). Local pathologists were centrally trained using the Residual Cancer Burden (RCB) assessment to ensure uniform evaluation and response classification; RCB 0 = pCR. Results: We evaluated the relationship between pCR and event free (EFS) and distant disease free survival (DDFS) in the first 522 pts (median follow-up:2.5 years). 180 pts achieved pCR (36%) while 338 did not (RCB=1-3). There were 82 EFS and 65 DRFS events. Over the entire group (including all arms), pCR was highly associated with 3-year EFS (p 3-year survival (pCR group)Hazard Ratio OverallOverallHR+/HER2-HER2+TNBCEFS97%0.08 (0.03-0.23)0.14 (0.02-1.04)0 (NA)0.11 (0.03-0.37)DDFS98%0.08 (0.03-0.26)0.17 (0.01-1.23)0 (NA)0.09 (0.02-0.40) Conclusions: The first long-term efficacy results from the I-SPY2 TRIAL demonstrate that achieving pCR is a very strong surrogate endpoint for improved EFS and DDFS in a high-risk population, across all treatment arms, regardless of subtype. I-SPY2 shows substantially lower estimated EFS hazards for patients achieving pCR, compared to the 5 yr EFS hazard ratio for pCR vs not in Cortazar (hazard ratio 0.49), demonstrating important differences between a metaanalysis compared to a platform trial with uniform high-risk eligibility, standardized pathology assessment, and multiple targeted therapies. Our data support the use of pCR as a primary endpoint for accelerated approval of new drugs if EFS is evaluated in the same population. Based on these findings, the I-SPY2 TRIAL will test whether therapy can be deescalated or escalated for individual patients with the goal of achieving pCR for all. Citation Format: Yee D, DeMichele A, Isaacs C, Symmans F, Yau C, Albain KS, Hylton NM, Forero-Torres A, van't Veer LJ, Perlmutter J, Rugo HS, Melisko M, Chen Y-Y, Balassanian R, Krings G, Datnow B, Hasteh F, Tipps A, Weidner N, Zhang H, Tickman R, Thornton S, Ritter J, Amin K, Klein M, Chen B, Keeney G, Ocal T, Feldman M, Klipfel N, Sattar H, Mueller J, Gwin K, Baker G, Kallakury B, Zeck J, Duan X, Ersahin C, Gamez R, Troxell M, Mansoor A, Grasso LeBeau L, Sams S, Wisell J, Wei S, Harada S, Vinh T, Stamatakos MD, Tawfik O, Fan F, Adams A, Rendi M, Minton S, Magliocco A, Sahoo S, Fang Y, Hirst G, Singhrao R, Asare SM, Wallace AM, Chien AJ, Ellis ED, Han HS, Clark AS, Boughey JC, Elias AD, Nanda R, Korde L, Murthy R, Lang J, Northfelt D, Khan Q, Edmiston KK, Viscusi R, Haley B, Kemmer K, Zelnak A, Berry DA, Esserman LJ. Pathological complete response predicts event-free and distant disease-free survival in the I-SPY2 TRIAL [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr GS3-08.