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Breast cancer; Cancer Càncer de mama; Càncer Cáncer de mama; Cáncer The METRIC study (NCT#0199733) explored a novel antibody–drug conjugate, glembatumumab vedotin (GV), targeting gpNMB that is overexpressed in ~40% of patients with triple-negative breast cancer (TNBC) and associated with poor prognosis. The study was a randomized, open-label, phase 2b study that evaluated progression-free survival (PFS) of GV compared with capecitabine in gpNMB-overexpressing TNBC. Patients who had previously received anthracycline and taxane-based therapy were randomized 2:1 to receive, GV (1.88 mg/kg IV q21 days) or capecitabine (2500 mg/m2 PO daily d1–14 q21 days). The primary endpoint was RECIST 1.1 PFS per independent, blinded central review. In all, 327 patients were randomized to GV (213 treated) or capecitabine (92 treated). Median PFS was 2.9 months for GV vs. 2.8 months for capecitabine. The most common grade ≥3 toxicities for GV were neutropenia, rash, and leukopenia, and for capecitabine were fatigue, diarrhea, and palmar-plantar erythrodysesthesia. The study did not meet the primary endpoint of improved PFS over capecitabine or demonstrate a relative risk/benefit improvement over capecitabine. Funding provided by Celldex Therapeutics, Inc.

The NCCN Guidelines for Breast Cancer include up-to-date guidelines for clinical management of patients with carcinoma in situ, invasive breast cancer, Paget disease, phyllodes tumor, inflammatory breast cancer, male breast cancer, and breast cancer during pregnancy. These guidelines are developed by a multidisciplinary panel of representatives from NCCN Member Institutions with breast cancer–focused expertise in the fields of medical oncology, surgical oncology, radiation oncology, pathology, reconstructive surgery, and patient advocacy. These NCCN Guidelines Insights focus on the most recent updates to recommendations for adjuvant systemic therapy in patients with nonmetastatic, early-stage, hormone receptor–positive, HER2-negative breast cancer.

Purpose: Patients with triple-negative breast cancer (TNBC) with homologous recombination deficient tumors achieve significantly higher pathologic complete response (pCR) rates when treated with neoadjuvant platinum-based therapy. Tumor-infiltrating lymphocytes (TIL) are prognostic and predictive of chemotherapy benefit in early stage TNBC. The relationship between TILs, BRCA1/2 mutation status, and homologous recombination deficiency (HRD) status in TNBC remains unclear. Experimental Design: We performed a pooled analysis of five phase II studies that included patients with TNBC treated with neoadjuvant platinum-based chemotherapy to evaluate the association of TILs with HRD status (Myriad Genetics) and tumor BRCA1/2 mutation status. Furthermore, the relationship between pathologic response assessed using the residual cancer burden (RCB) index and HRD status with adjustment for TILs was evaluated. Results: Among 161 patients, stromal TIL (sTIL) density was not significantly associated with HRD status (P = 0.107) or tumor BRCA1/2 mutation status (P = 0.391). In multivariate analyses, sTIL density [OR, 1.23; 95% confidence interval (CI), 0.94–1.61; P = 0.139] was not associated with pCR, but was associated with RCB 0/I status (OR 1.62; 95% CI, 1.20–2.28; P = 0.001). HRD was significantly associated with both pCR (OR 12.09; 95% CI, 4.11–44.29; P = 7.82 × 10−7) and RCB 0/I (OR 10.22; 95% CI, 4.11–28.75; P = 1.09 × 10−7) in these models. Conclusions: In patients with TNBC treated with neoadjuvant platinum-based therapy, TIL density was not significantly associated with either tumor BRCA1/2 mutation status or HRD status. In this pooled analysis, HRD and sTIL density were independently associated with treatment response, with HRD status being the strongest predictor.

Background: Avelumab, a human IgG1 anti–PD-L1 monoclonal antibody, has shown antitumor activity and a manageable safety profile in several tumor types. Talazoparib, an orally available PARP inhibitor, is approved for the treatment of patients with deleterious or suspected deleterious germline BRCA1/2-mutated HER2− locally advanced (LA) or metastatic (M) breast cancer (BC). Preclinical data suggest that PARP inhibitors may have synergistic activity when administered in combination with immune checkpoint inhibitors. We report results from patients with LA/MBC enrolled in the phase 1b/2, multicohort JAVELIN PARP Medley study (NCT03330405). Methods: In phase 1b (cohort 1), patients with advanced solid tumors who had received ≥1 prior standard of care chemotherapy (CT) regimen were treated with avelumab 800 mg IV every 2 weeks (Q2W) in combination with talazoparib 1.0 mg orally once daily (QD) (dose de-escalation to 0.75 or 0.5 mg permitted following toxicity). In 2 phase 2 cohorts, eligible patients had either LA/M triple-negative BC (TNBC, cohort 2A) or LA/M hormone receptor positive (HR+), HER2−, DNA damage repair defect-positive BC (cohort 2B). Patients in cohort 2A had received 0 to 2 prior CT regimens (no progression on prior platinum-based CT) and patients in cohort 2B had received prior standard of care hormone therapy in either the adjuvant and/or LA/M setting followed by 0 to 2 prior CT regimens (no progression on prior platinum-based CT). The primary endpoint for phase 1b was first-cycle dose-limiting toxicities (DLTs) and for phase 2 was objective response (investigator assessed per RECIST v1.1). Adverse events (AEs) were characterized using National Cancer Institute Common Terminology Criteria for AEs v4.03. Results: By the data cutoff on December 24, 2018, 34 patients had been treated in cohorts 1 and 2. Twelve patients with advanced solid tumors were treated in cohort 1 (including 2 patients with TNBC); 3 patients (25.0%) had a first-cycle DLT: grade 3 neutropenia, (n=1) and grade 3 thrombocytopenia, (n=2). Best overall response (BOR) was partial response (PR) in 1 patient, stable disease (SD) in 3, progressive disease (PD) in 6, and non-complete response/non-PD in 1 patient with metastatic castration-resistant prostate cancer and non-measurable disease at baseline; 1 patient was not evaluable for response. Both patients with TNBC had a BOR of SD and remained on treatment for ≥9 months. Objective response rate in this pre-treated and heterogenous population was 8.3% (95% CI, 0.2, 38.5). Based on the phase 1b data, the recommended phase 2 dose was avelumab 800 mg Q2W and talazoparib 1 mg QD. By data cutoff, 22 patients had been treated in cohorts 2A (n=19) and 2B (n=3); median age was 56 and 50 years, respectively. In cohort 2A, 12 patients were evaluable for disease assessment; BOR was PR in 1, SD in 6, and PD in 5. All 3 patients in cohort 2B were non-evaluable for response at data cutoff. Treatment-related AEs (TRAEs) of any grade occurred in 11 patients (91.7%) in cohort 1, and 18 (94.7%) patients in cohort 2A. In cohort 2A, the most common TRAEs were anemia (57.9%), nausea (26.3%), fatigue (21.1%) and thrombocytopenia (21.1%); 9 patients (47.4%) had grade ≥3 TRAEs. There were no treatment-related deaths. Safety data from cohort 2B are not reported owing to low patient numbers. Observed pharmacokinetic (PK) data for avelumab 800 mg Q2W were similar to simulated data derived from a population PK model developed using 10 mg/kg dosing. Conclusions: Avelumab 800 mg Q2W administered in combination with talazoparib 1 mg QD in patients with advanced solid tumors, showed preliminary antitumor activity and a manageable safety profile, which was comparable to the safety profiles of the single agents. The study is ongoing; updated safety and efficacy data, and biomarker data will be presented. Citation Format: Timothy A Yap, Panagiotis Konstantinopoulos, Melinda L. Telli, Smita Saraykar, J Thaddeus Beck, Matthew D. Galsky, Jame Abraham, David R. Wise, Mustafa Khasraw, Gabor Rubovszky, Mikhail Dvorkin, Anil A Joy, Mateusz Opyrchal, Daria Stypinski, Colombe Chappey, Ross Stewart, Rossano Cesari, Anita Scheuber, Aditya Bardia. JAVELIN PARP Medley, a phase 1b/2 study of avelumab plus talazoparib: Results from advanced breast cancer cohorts [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 P1-19-03.

A randomized phase II study comparing surgical excision versus NeOadjuvant Radiotherapy followed by delayed surgical excision of Ductal carcinoma In Situ (NORDIS) Breast radiotherapy (RT) for DCIS has been studied only in the adjuvant setting, following lumpectomy surgery. Adjuvant RT reduced invasive recurrences by 52% in the combined analysis of the two largest DCIS trials NSABP B-17/B-24, and reduced recurrences even for low or intermediate grade DCIS in the RTOG 9804 trial (recurrence 0.9% with RT versus 6.7% without RT). The mechanism of action is hypothesized to be elimination of occult disease and/or inhibition of neoplastic transformation in normal breast tissue. Trial Design To understand the ablative effects of RT on pure DCIS, we are conducting a prospective randomized trial comparing histopathological findings of surgical excision (Arm 1) to neoadjuvant partial breast irradiation (neoRT) followed by delayed surgical excision (Arm 2) for patients with core needle biopsy proven DCIS. Arm 1 will provide a reference group for upstaging to invasive cancer, molecular markers and pathological-radiological correlations. Arm 2 participants will receive 6 Gy daily x 5 to the intact tumor with a 0.5 cm margin of normal tissue. Surgical excision will be delayed 12-16 weeks to allow for the radioablative effects to occur and radiation-induced inflammation to subside. Specific Aims To determine if neoRT can completely ablate at least 30% of pure DCISTo determine if DCIS subtypes exhibit differential sensitivity to neoRTTo determine the radiation-induced treatment effects; wound complication rates; radiological Eligibility Women 18 years of age or older with DCIS diagnosed on vacuum assisted core needle biopsy who intend to receive breast conserving surgery are eligible, excluding those with a prior history of ipsilateral breast cancer. The imaging abnormality must be mammographic microcalcifications and/or MRI non-mass enhancement measuring Statistics A total of 50 patients will be recruited. Upstaging to invasive cancer is anticipated to be approximately 10% in the reference group. With 25 subjects in each arm, we will have 80% power to detect a 30% or higher improvement in the DCIS complete response rate following neoRT. Accrual Opened to accrual June 1, 2019 Contact wapnir@stanford.edu Wapnir IL, Dignam JJ, Fisher B, et al. Long-term outcomes of invasive ipsilateral breast tumor recurrences after lumpectomy in NSABP B-17 and B-24 randomized clinical trials for DCIS. J Natl Cancer Inst. 2011;103(6):478-488. doi:10.1093/jnci/djr027. McCormick B, Winter K, Hudis C, et al. RTOG 9804: a prospective randomized trial for good-risk ductal carcinoma in situ comparing radiotherapy with observation. J Clin Oncol. 2015;33(7):709-715. doi:10.1200/JCO.2014.57.9029. Citation Format: Irene Wapnir, Wendy DeMartini, Kimberly Allison, Kimberly Stone, Frederick Dirbas, Carol Marquez, Debra Ikeda, Sunita Pal, Jacqueline Tsai, Rachel Yang, Robert West, Alex McMillan, Melinda Telli, Kathleen Horst. A randomized phase II study comparing surgical excision versus NeOadjuvant Radiotherapy followed by delayed surgical excision of Ductal carcinoma In Situ (NORDIS) [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 OT3-09-04.

BACKGROUND: Anti-PD-1 checkpoint inhibitor (CPI) monotherapy has demonstrated modest activity in pre-treated mTNBC, with single digit objective response rates (ORR) observed. Our prior data suggests that local electroporation after intratumoral administration of tavokinogene telseplasmid (IT-tavo-EP), a plasmid encoding the proinflammatory cytokine IL-12, can render CPI non-responsive pre-treated mTNBC sensitive to CPI therapy. The phase II KEYNOTE-890/OMS-I141 study was therefore designed to evaluate IT-tavo-EP and IV pembrolizumab in patients with mTNBC previously treated with chemotherapy +/- CPI therapy. METHODS: Patients with histologically confirmed inoperable locally advanced or metastatic TNBC with at least 1 line of prior systemic therapy for advanced disease, including prior CPI therapy, were eligible. Patients were required to have RECIST v1.1 measurable disease with at least 1 anatomically distinct cutaneous or subcutaneous lesion accessible for intratumoral injection and electroporation. Scans were obtained every 12 weeks. Patients received pembrolizumab 200 mg IV on day 1 of each 3-week cycle and IT-tavo-EP at a concentration of 0.5 mg/mL and dose volume of ~1/4 of the calculated lesion volume to the accessible lesion(s) on days 1, 5, and 8 every 6 weeks. The primary endpoint of this open-label, non-randomized phase II trial is ORR by investigator review. Secondary endpoints include safety and tolerability of the combined therapy, duration of response, progression-free survival (PFS), immune PFS and overall survival. The correlation between changes in the immune cell subsets and response to treatment was also evaluated. RESULTS: At the time of abstract submission, 16 of the planned 25 patients have been enrolled and 11 patients completed a post-treatment RECIST v1.1 assessment at the initial 12-week evaluation or discontinued prior to assessment. Patients had a median of 3 prior lines of therapy for advanced disease. Partial responses have been observed in 3 patients (ORR 27.3%), including a deep confirmed response in a patient with multiple liver, bone, skin and nodal metastases and a short disease-free interval following neoadjuvant chemotherapy. Regression of IT-tavo-EP untreated lesions have been observed. Treatment was well tolerated and any grade treatment emergent adverse events (AEs) regardless of attribution were observed in 11 of 16 (68.8%) [grade ≥3 in 6 of 16 (37.5%)]. Only one grade ≥3 AE was attributed to pembrolizumab and none were attributed to IT-tavo or EP. Patients demonstrated immunological responses in blood consistent with an IL-12-associated mechanism of action, including on-treatment reduction of peripheral gMDSC suppressors. Additional biomarker analysis of patient tumor and blood samples are ongoing. CONCLUSIONS: When compared to the results of KEYNOTE-086, which demonstrated a 5.3% ORR in pretreated mTNBC patients with pembrolizumab monotherapy, our preliminary data from patients who have reached an assessment time-point suggests that IT-tavo-EP may enhance sensitivity to pembrolizumab in this patient population. Updated data will be presented. Citation Format: Melinda L. Telli, Irene Wapnir, Bianca Devitt, Katharine Cuff, Hatem Soliman, Shaveta Vinayak, David A. Canton, Christopher Twitty, Kellie Malloy Foerter, Rohit Joshi. Phase 2, open-label study of intratumoral tavokinogene telseplasmid (tavo) plus electroporation in combination with intravenous pembrolizumab therapy in patients with inoperable locally advanced or metastatic triple-negative breast cancer (mTNBC) (KEYNOTE- 890/OMS-I141) [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P3-09-04.

PURPOSE: To understand genetic testing use and decision making among patients with high genetic risk. MATERIALS AND METHODS: A survey of breast cancer survivors was administered online by a hereditary cancer nonprofit organization, Facing Our Risk of Cancer Empowered, from October 2017 to March 2018. RESULTS: Of 1,322 respondents, 46% had breast cancer at age < 45 years, 61% had a first-degree relative with cancer, and 84% underwent genetic testing, of whom 56% had a risk-associated pathogenic variant. Most (86%; 95% CI, 84% to 88%) tested respondents were very satisfied with their testing decision, versus 34% (95% CI, 27% to 41%) of untested respondents. Factors that encouraged testing included relatives’ cancer risk (75%; 95% CI, 73% to 78%), clinicians’ recommendations (68%; 95% CI, 66% to 71%), and potential treatment implications (67%; 95% CI, 64% to 69%). Factors that discouraged testing included insurance concerns (14%; 95% CI, 12% to 16%), cost (14%; 95% CI, 12% to 16%), and discrimination (9%; 95% CI, 7% to 11%). Thirty-nine percent (95% CI, 36% to 41%) recalled hearing from a clinician that genetic discrimination is illegal. Respondents often recalled clinicians informing them about inheritance patterns (65%; 95% CI, 62% to 67%), surgical implications (65%; 95% CI, 63% to 68%), and other cancer risks (66%; 95% CI, 63% to 68%) but less often that results could have potential implications for clinical trial eligibility (38%; 95% CI, 36% to 42%) or targeted therapies (14%; 95% CI, 12% to 16%). Patients who had genetic counseling were twice as likely to recall clinicians informing them about all queried topics. Results did not vary by diagnosis year. CONCLUSION: Among patients with high genetic risk, clinicians’ recommendations, potential treatment implications, and protections against discrimination were motivating factors to undergo genetic testing, but fewer than half recalled clinicians providing all this information, and this did not improve over time. Clinicians influence testing decisions and should inform patients about legal protections and treatment implications.

Background: Talazoparib, a PARP1 inhibitor, is active in germline BRCA1/2 mutant advanced HER2-negative breast cancer, but its activity beyond BRCA1/2 less well understood. The Talazoparib Beyond BRCA clinical trial treated 20 patients with germline (g) or somatic (s) mutations in HR pathways genes other than BRCA1/2, which included PALB2, CHEK2, ATM, BRIP1, RAD50, ATR, PTEN, and FANCA. Talazoparib treatment was associated with a 31% overall response rate in patients with breast cancer, including tumor regression from baseline as best response in 6 out of 6 patients treated gPALB2 mutations. We now present the results of additional genomic studies to further characterize treatment responses and resistance mechanisms. Methods: Primary and metastatic tumor biopsies were assessed using the commercially-available next-generation sequencing HRD assay (Myriad). Panel gene sequencing of tumors was performed for 108 genes associated with genomic instability. Loss-of-heterozygosity (LOH) was assessed in tumors. Tumor/normal exome sequencing identified pre-treatment somatic variants. Circulating-tumor DNA at baseline and disease progression was assessed by targeted panel sequencing and plasma whole exome sequencing. Results: Of the 18 HRD assays performed, 3 failed and were thus excluded. Seven patients had HRD analysis performed on both primary and metastatic tumors. For these patients the HRD score was significantly higher in the metastasis versus the primary (means 46.2 versus 36.5, p = 0.018 by paired t-test). By panel sequencing of tumors (n=18) the most common alterations detected included mutations in PIK3CA (n=8), PALB2 (n=6), ATM (n=5), KRAS (n=4), PTEN (n=5) and TP53 (n=4). In all cases except one, the HR-associated mutation used as entry criteria were detected. LOH analysis showed that of tumors with gPALB2 mutations, 3 of the 6 had LOH for PALB2, and an additional two tumors had 2 independent PALB2 mutations suggesting bi-allelic inactivation. The one remaining tumor had an uncertain LOH result due to test failure. Thus, it is likely that most, if not all, of the tumors in our cohort with gPALB2 mutations had complete inactivation of PALB2 gene function. Other detected mutations that were associated with LOH included all sTP53 mutations (n=4), all gCHEK2 mutations (n=3), gFANCA (n=1), all sRB1 mutations (n=3) and NF1 (n=1). Of the three gATM mutations one had LOH, while the others had two independent mutations, suggestive of bi-allelic inactivation. sATM mutations were associated with LOH in a breast cancer and with 2 independent (possibly bi-allelic) mutations in a non-breast cancer. Additional results from ctDNA targeted sequencing and plasma whole exome sequencing of baseline and progression samples will be presented. Conclusions: In this proof-of-concept phase II study, talazoparib demonstrated activity in HER2-negative advanced breast cancer patients with a HR pathway mutation beyond BRCA1/2, especially in patients with gPALB2 mutations and high HRD scores. These additional genomic analyses provide evidence that HRD scores may be significantly higher in metastatic samples compared to primary tumors. Also, we detected either LOH or bi-allelic inactivation for most HR-associated mutations used to determine eligibility. These findings may inform selection of patients for PARP inhibitor monotherapy beyond BRCA1/2. Citation Format: Joshua J Gruber, Anosheh Afghahi, Alyssa Hatton, Wyatt Gross, Jessica Foran, Alex McMillan, James M Ford, Melinda L Telli. Genomic analysis from the talazoparib beyond BRCA clinical trial: Homologous recombination (HR) deficiency scores, loss-of-heterozygosity and mutations in non-BRCA1/2 mutant tumors with other HR mutations [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 PD10-12.

Purpose: To assess talazoparib activity in germline BRCA1/2 mutation carriers with advanced breast cancer. Patients and Methods: ABRAZO (NCT02034916) was a two-cohort, two-stage, phase II study of talazoparib (1 mg/day) in germline BRCA mutation carriers with a response to prior platinum with no progression on or within 8 weeks of the last platinum dose (cohort 1) or ≥3 platinum-free cytotoxic regimens (cohort 2) for advanced breast cancer. Primary endpoint was confirmed objective response rate (ORR) by independent radiological assessment. Results: We enrolled 84 patients (cohort 1, n = 49; cohort 2, n = 35) from May 2014 to February 2016. Median age was 50 (range, 31–75) years. Triple-negative breast cancer (TNBC) incidence was 59% (cohort 1) and 17% (cohort 2). Median number of prior cytotoxic regimens for advanced breast cancer was two and four, respectively. Confirmed ORR was 21% [95% confidence interval (CI), 10–35; cohort 1] and 37% [95% CI, 22–55; cohort 2]. Median duration of response was 5.8 and 3.8 months, respectively. Confirmed ORR was 23% (BRCA1), 33% (BRCA2), 26% (TNBC), and 29% (hormone receptor–positive). The most common all-grade adverse events (AE) included anemia (52%), fatigue (45%), and nausea (42%). Talazoparib-related AEs led to drug discontinuation in 3 (4%) patients. In an exploratory analysis, longer platinum-free interval was associated with higher response rate in cohort 1 (0% ORR with interval 6 months). Conclusions: Talazoparib exhibited promising antitumor activity in patients with advanced breast cancer and germline BRCA mutation.

Introduction: Triple negative breast cancer (TNBC) accounts for approximately 15% of breast cancer diagnoses and is associated with a higher risk of recurrence and more aggressive course in the metastatic setting. Emerging data suggest that some patients with TNBC benefit from immune-based therapies targeting the anti-programmed cell death protein 1 (PD-1)/PD-1 ligand 1 (PD-L1) axis, but success has been limited in poorly immunogenic tumors. Thus, combination therapies that drive an influx of CD8+ tumor infiltrating lymphocytes (TILs) and/or upregulate PD-L1 expression are required to increase response rates to these therapeutics. Intratumoral injection of plasmid IL-12 (tavokinogene telseplasmid; tavo) followed by electroporation (IT-tavo-EP) is a gene therapy approach that drives local expression of the proinflammatory cytokine, interleukin-12 (IL-12). Local expression of IL-12 is hypothesized to result in increased TILs and enhanced expression of proinflammatory cytokines, resulting in conversion of poorly-immunogenic/low TIL TNBC tumors into highly inflamed immunologically active lesions while demonstrating a high safety profile. Methods: OMS-I140 is a phase I, non-randomized, open-label study of IT-tavo-EP in patients with inoperable locally advanced, metastatic and/or treatment-refractory TNBC (NCT02531425). Eligible patients have pre-treated TNBC and at least 2 anatomically distinct cutaneous or subcutaneous lesions accessible for injection and electroporation, with or without other regional or distant metastases. 10 patients are planned for enrollment. IT-tavo-EP is administered on Days 1, 5 and 8 of a single 28-day cycle. Tavo is injected intratumorally (based on tumor volume) at a concentration of 0.5 mg/mL and immediately followed by co-localized electroporation (6 pulses at 1500 V/cm with 1-second intervals). Tumor biopsies are obtained at baseline and post-treatment on day 28 of both treated and untreated lesions to determine if this therapy can promote a pro-inflammatory molecular and histologic signature. Pain scores and adverse events are recorded. Results: To date, nine patients have completed study therapy. Reported treatment-related adverse events include pain associated with electroporation (grade 1) in 8 patients and fatigue (grade 1) in 1 patient. Median pain score (range 0-10) immediately after treatment was 2 (range 0-10) and 5 minutes post-treatment was 0 (range 0-6). In some patients, treatment-related increases in CD8+ TIL density have been observed by intratumoral chromogenic staining. Further immune profiling is being conducted to characterize the tumor microenvironment pre- and post-therapy. A subset of patients with treatment refractory TNBC received anti-PD-1 monotherapy as their immediate next therapy with clinical response observed. Updated data will be presented. Conclusions: Our data suggest that IT-tavo-EP is a safe and tolerable TIL stimulating therapy in TNBC. Further study of IT-tavo-EP in combination with pembrolizumab in pretreated metastatic TNBC is planned. Citation Format: Telli ML, Zablotsky K, Le MH, Canton D, Browning E, Bannavong D, Gargosky S, Wapnir I. Intratumoral tavokinogene telseplasmid and electroporation in pre-treated inoperable locally advanced or recurrent triple-negative breast cancer [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 P2-09-11.

Background: Emerging data suggest that some patients with TNBC could benefit from the addition of immune-based therapy. This observation is in part due to the significant association between distinct tumor-infiltrating lymphocytes (TILs) and prognosis in TNBC. Efforts to comprehensively characterize the immune microenvironment of TNBCs are critically important to gain a better understanding of the immune landscape and how it influences response to both standard chemotherapy and immunotherapy. We previously assessed both stromal TILs (sTILs) and intraepithelial TILs (iTILs) from pre-treatment tumor samples from patients enrolled on a phase II study of neoadjuvant gemcitabine, carboplatin and iniparib (PrECOG 0105; NCT00813956). We found that both iTILS and sTILS significantly associated with pathologic response. Furthermore, we assessed a novel 'in silico flow cytometry' gene expression-based method, CIBERSORT, designed to assess overall immune content and deconvolute the relative levels of distinct leukocyte subsets in tumors. Specific leukocyte subsets significantly associated with pCR included activated memory CD4+ T cells, CD8+ T cells and M1 macrophages (all p Methods: We performed SPARTA - Spatial Perception And Regional Tumor Analysis - a multiplexed immunohistochemistry-based technology with data visualization and analysis modules that is designed to capture clinically relevant information about the tumor microenvironment in 72 pre-treatment FFPE tumor sections from patients enrolled on PrECOG 0105. SPARTA was used to test and analyze the coordinated expression of PD-L1, PD-1, CD45RO, CD4, CD8 and HLA-DRA in the study cohort from whole slide scanned images. Pathologic response at the time of surgery was evaluated using the residual cancer burden index. Germline BRCA1 and BRCA2 status was known for all patients. Results: Of 72 samples, 67 were evaluable for SPARTA analysis. Within a subset of tumors separately profiled by both SPARTA (FFPE/IHC microscopy) and CIBERSORT (Frozen/RNA GEP), we found significant correlation for clinically relevant TIL subpopulations, including for CD8+ T cells (r=0.83, p Conclusions: Spatial mapping of the immune microenvironment in primary TNBC reveals distinct immune cell populations associated with response to neoadjuvant platinum-based therapy. Citation Format: Telli ML, Vinayak S, Khododoust MS, Gruber JJ, Ford JM, Sanchez P, Banayan N, Azimi S, Tumeh PC, Newman AM, Alizadeh AA. Spatial mapping of the immune microenvironment in primary triple-negative breast cancer (TNBC) and association with neoadjuvant therapy response [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr PD5-12.

Background gpNMB is an internalizable transmembrane protein overexpressed in ˜40% of TNBC, and associated with a worse prognosis. Preclinical data implicates gpNMB in tumor invasion and metastasis. GV is a novel ADC designed to deliver monomethyl auristatin E (MMAE) to gpNMB-overexpressing cells. Prior phase 1/2 studies suggested promising activity of GV in gpNMB-overexpressing TNBC. Methods In the METRIC trial (NCT#01997333), patients (pts) with mTNBC were randomized 2:1 to GV (1.88 mg/kg IV q21 days) or capecitabine (2,500 mg/m2 PO daily d1-14 q21 days) until disease progression or intolerance. Key eligibility criteria included: gpNMB over-expression (>25% tumor cells positive by central immunohistochemistry of archival tissue); estrogen and progesterone receptor expression Results From Feb 2014 to Aug 2017, 327 women were randomized at 120 institutions to GV (n=218) or capecitabine (n=109). Pretreatment characteristics were well balanced between arms: median age of 55 years; 77% visceral disease; 2.4 years median duration of disease at study entry; 1 median prior anticancer regimen for metastatic disease. At the cut-off for final data analysis (Nov 30, 2017), 21 pts remained on treatment and 98 pts were alive. For GV vs. capecitabine based on independent central review, median PFS was 2.9 (95% CI: 2.8, 3.5) vs. 2.8 (95% CI: 1.6, 3.2) months (HR=0.95; p=0.76); median OS was 8.9 (95% CI: 7.9, 10.5) vs. 8.7 (95% CI: 6.9, 10.8) months (HR=1.06; p=0.73); ORR was 16% (95% CI: 11.1, 22.4) vs. 15% (95% CI: 8.6, 23.5); and median DOR was 5.6 (95% CI: 3.0, 7.8) vs. 4.2 (95% CI: 3.0, 12.2) months. A post-hoc subgroup analysis suggested the greatest benefit from GV was in potentially taxane-sensitive disease (i.e., not previously rechallenged or >6 months progression-free interval following last taxane). The incidence of grade ≥ 3 treatment-related adverse events (TRAEs) was 58% in the GV arm and 37% in the capecitabine arm. The most common grade ≥ 3 TRAEs were neutropenia (27%), rash (15%), and leukopenia (9%) in the GV arm, and diarrhea (14%) and palmar-plantar erythryodysesthesia (8%) in the capecitabine arm. There was 1 fatal TRAE of neutropenic sepsis in the GV arm and none in the capecitabine arm. Conclusion The METRIC study evaluating GV in mTNBC did not meet the primary efficacy endpoint of improved PFS over capecitabine. While anticancer activity was seen with GV, it was comparable to capecitabine with no therapeutic advantage of GV in terms of ORR, PFS, or OS. The safety profile of GV was consistent with prior experience with no new safety signals identified. Citation Format: Vahdat LT, Forero-Torres A, Schmid P, Blackwell K, Telli ML, Melisko M, Holgado E, Moebus V, Cortes J, Fehrenbacher L, Montero AJ, Ma C, Nanda R, Wright GS, He Y, Bagley RG, Halim A, Turner CD, Yardley DA. METRIC: A randomized international phase 2b study of the antibody-drug conjugate (ADC) glembatumumab vedotin (GV) in gpNMB-overexpressing, metastatic, triple-negative breast cancer (mTNBC) [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P6-20-01.

Triple negative breast cancer (TNBC) accounts for 10-20% of breast cancer diagnoses and is associated with a high risk of recurrence and a more aggressive course in the metastatic setting. Emerging data suggest that some patients with TNBC could benefit from the addition of immune-based therapy due to the important role of tumor infiltrating lymphocytes (TILs) on outcome. Reports show that early-stage TNBC patients with at least 50% TILs demonstrate longer disease-free survival. Additionally, immune-modulating therapies, like the anti-PD-1/PD-L1 monoclonal antibodies, have demonstrated modest activity in the pre-treated metastatic TNBC population with objective response rates (ORR) Citation Format: Telli ML, Wapnir I, Vinayak S, Chang J, Alemany C, Twitty C, Gargosky S. A phase 2 study of intratumoral tavokinogene telseplasmid (tavo) plus electroporation with pembrolizumab in patients with inoperable locally advanced or metastatic triple negative breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr OT2-06-03.

These NCCN Guidelines Insights highlight the updated recommendations for use of multigene assays to guide decisions on adjuvant systemic chemotherapy therapy for women with hormone receptor–positive, HER2-negative early-stage invasive breast cancer. This report summarizes these updates and discusses the rationale behind them.

Purpose: Triple-negative breast cancer (TNBC) is an aggressive disease with limited therapeutic options. Antibodies targeting programmed cell death protein 1 (PD-1)/PD-1 ligand 1 (PD-L1) have entered the therapeutic landscape in TNBC, but only a minority of patients benefit. A way to reliably enhance immunogenicity, T-cell infiltration, and predict responsiveness is critically needed. Patients and Methods: Using mouse models of TNBC, we evaluate immune activation and tumor targeting of intratumoral IL12 plasmid followed by electroporation (tavokinogene telseplasmid; Tavo). We further present a single-arm, prospective clinical trial of Tavo monotherapy in patients with treatment refractory, advanced TNBC (OMS-I140). Finally, we expand these findings using publicly available breast cancer and melanoma datasets. Results: Single-cell RNA sequencing of murine tumors identified a CXCR3 gene signature (CXCR3-GS) following Tavo treatment associated with enhanced antigen presentation, T-cell infiltration and expansion, and PD-1/PD-L1 expression. Assessment of pretreatment and posttreatment tissue from patients confirms enrichment of this CXCR3-GS in tumors from patients that exhibited an enhancement of CD8+ T-cell infiltration following treatment. One patient, previously unresponsive to anti–PD-L1 therapy, but who exhibited an increased CXCR3-GS after Tavo treatment, went on to receive additional anti–PD-1 therapy as their immediate next treatment after OMS-I140, and demonstrated a significant clinical response. Conclusions: These data show a safe, effective intratumoral therapy that can enhance antigen presentation and recruit CD8 T cells, which are required for the antitumor efficacy. We identify a Tavo treatment-related gene signature associated with improved outcomes and conversion of nonresponsive tumors, potentially even beyond TNBC.

PURPOSE The aim of this work is to update key recommendations of the ASCO guideline adaptation of the Cancer Care Ontario guideline on the selection of optimal adjuvant chemotherapy regimens for early breast cancer and adjuvant targeted therapy for breast cancer. METHODS An Expert Panel conducted a targeted systematic literature review guided by a signals approach to identify new, potentially practice-changing data that might translate into revised guideline recommendations. RESULTS The Expert Panel reviewed abstracts from the literature review and identified one article for inclusion that reported results of the phase III, open-label KATHERINE trial. In the KATHERINE trial, patients with stage I to III human epidermal growth factor receptor 2 (HER2)–positive breast cancer with residual invasive disease in the breast or axilla after completing neoadjuvant chemotherapy and HER2-targeted therapy were allocated to adjuvant trastuzumab emtansine (T-DM1; n = 743) or to trastuzumab (n = 743). Invasive disease–free survival was significantly higher in the T-DM1 group than in the trastuzumab arm (hazard ratio, 0.50; 95% CI, 0.39 to 0.64; P < .001), and risk of distant recurrence was lower in patients who received T-DM1 than in patients who received trastuzumab (hazard ratio, 0.60; 95% CI, 0.45 to 0.79). Grade 3 or higher adverse events occurred in 190 patients (25.7%) who received T-DM1 and in 111 patients (15.4%) who received trastuzumab. RECOMMENDATIONS Patients with HER2-positive breast cancer with pathologic invasive residual disease at surgery after standard preoperative chemotherapy and HER2-targeted therapy should be offered 14 cycles of adjuvant T-DM1, unless there is disease recurrence or unmanageable toxicity. Clinicians may offer any of the available and approved formulations of trastuzumab, including trastuzumab, trastuzumab and hyaluronidase-oysk, and available biosimilars. Additional information can be found at www.asco.org/breast-cancer-guidelines

This selection from the NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines) for Bladder Cancer focuses on the clinical presentation and workup of suspected bladder cancer, treatment of non-muscle-invasive urothelial bladder cancer, and treatment of metastatic urothelial bladder cancer because important updates have recently been made to these sections. Some important updates include recommendations for optimal treatment of non-muscle-invasive bladder cancer in the event of a bacillus Calmette-Guerin (BCG) shortage and details about biomarker testing for advanced or metastatic disease. The systemic therapy recommendations for second-line or subsequent therapies have also been revised. Treatment and management of muscle-invasive, nonmetastatic disease is covered in the complete version of the NCCN Guidelines for Bladder Cancer available at NCCN.org. Additional topics covered in the complete version include treatment of nonurothelial histologies and recommendations for nonbladder urinary tract cancers such as upper tract urothelial carcinoma, urothelial carcinoma of the prostate, and primary carcinoma of the urethra.

Background Talazoparib (1 mg/day) exhibited promising efficacy and safety in patients with advanced breast cancer during ABRAZO (NCT02034916); this study evaluated patient-reported outcomes (PROs). Patients and methods ABRAZO is a two-cohort, two-stage, phase 2 study of talazoparib in patients with advanced breast cancer after a response to prior platinum-based therapy (cohort 1 [C1], n = 49) or ≥3 platinum-free cytotoxic-based regimens (cohort 2 [C2], n = 35). PROs were assessed on day 1 (baseline), every 6 weeks for an initial 24 weeks, and every 12 weeks thereafter until progression, using the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire Core 30 (QLQ-C30) and its breast cancer module, QLQ-BR23. Results Global health status/quality of life (GHS/QoL) was maintained from baseline across all time points for both C1 and C2. For C1 and C2, median time to deterioration (TTD) of GHS/QoL (95% confidence interval [CI]) was 2.8 (2.1, 3.0) and 5.5 (4.2, 5.7) months, respectively. Median TTD for all QLQ-C30 functional scales for C1 and C2 ranged 2.1–3.1 months and 4.2–5.6 months, respectively; median TTD for all QLQ-BR23 symptom scales ranged 2.6–4.0 months and 4.2–5.6 months, respectively. There were no statistically significant differences in estimated overall change from baseline in the GHS/QoL scale for both cohorts (C1: −2.6 [95% CI, −7.8, 2.5]; C2: 1.2 [95% CI, −5.5, 8.0]). Significant overall improvements in the breast symptoms and arm symptoms and the future perspective of patients in C1 and C2 were observed, despite the statistically significant and clinically meaningful overall deterioration among patients regarding their role functioning (in C1) and dyspnoea symptoms (in C2). Conclusion Despite the statistically significant and clinically meaningful overall deterioration among patients regarding their role functioning (in C1) and dyspnoea symptoms (in C2), patients in both C1 and C2 reported significant overall improvements in their breast symptoms, arm symptoms and future perspective, and their GHS/QoL was maintained from baseline.

Purpose This multicenter phase II trial evaluated lurbinectedin (PM01183), a selective inhibitor of active transcription of protein-coding genes, in patients with metastatic breast cancer. A unicenter translational substudy assessed potential mechanisms of lurbinectedin resistance. Patients and Methods Two arms were evaluated according to germline BRCA1/2 status: BRCA1/2 mutated (arm A; n = 54) and unselected ( BRCA1/2 wild-type or unknown status; arm B; n = 35). Lurbinectedin starting dose was a 7-mg flat dose and later, 3.5 mg/m2 in arm A. The primary end point was objective response rate (ORR) per Response Evaluation Criteria in Solid Tumors (RECIST). The translational substudy of resistance mechanisms included exome sequencing (n = 13) and in vivo experiments with patient-derived xenografts (n = 11) from BRCA1/2-mutated tumors. Results ORR was 41% (95% CI, 28% to 55%) in arm A and 9% (95% CI, 2% to 24%) in arm B. In arm A, median progression-free survival was 4.6 months (95% CI, 3.0 to 6.0 months), and median overall survival was 20.0 months (95% CI, 11.8 to 26.6 months). Patients with BRCA2 mutations showed an ORR of 61%, median progression-free survival of 5.9 months, and median overall survival of 26.6 months. The safety profile improved with lurbinectedin dose adjustment to body surface area. The most common nonhematologic adverse events seen at 3.5 mg/m2 were nausea (74%; grade 3, 5%) and fatigue (74%; grade 3, 21%). Neutropenia was the most common severe hematologic adverse event (grade 3, 47%; grade 4, 10%). Exome sequencing showed mutations in genes related to the nucleotide excision repair pathway in four of seven tumors at primary or acquired resistance and in one patient with short-term stable disease. In vivo, sensitivity to cisplatin and lurbinectedin was evidenced in lurbinectedin-resistant (one of two) and cisplatin-resistant (two of three) patient-derived xenografts. Conclusion Lurbinectedin showed noteworthy activity in patients with BRCA1/2 mutations. Response and survival was notable in those with BRCA2 mutations. Additional clinical development in this subset of patients with metastatic breast cancer is warranted.

Purpose To update key recommendations of the ASCO guideline adaptation of the Cancer Care Ontario guideline on the selection of optimal adjuvant chemotherapy regimens for early breast cancer and adjuvant targeted therapy for breast cancer. Methods An Expert Panel conducted targeted systematic literature reviews guided by a signals approach to identify new, potentially practice-changing data that might translate to revised practice recommendations. Results The Expert Panel reviewed phase III trials that evaluated adjuvant capecitabine after completion of standard preoperative anthracycline- and taxane-based combination chemotherapy by patients with early-stage breast cancer HER2-negative breast cancer with residual invasive disease at surgery; the addition of 1 year of adjuvant pertuzumab to combination chemotherapy and trastuzumab for patients with early-stage, HER2-positive breast cancer; and the use of neratinib as extended adjuvant therapy for patients after combination chemotherapy and trastuzumab-based adjuvant therapy with early-stage, HER2-positive breast cancer. Recommendations Patients with early-stage HER2-negative breast cancer with pathologic, invasive residual disease at surgery following standard anthracycline- and taxane-based preoperative therapy may be offered up to six to eight cycles of adjuvant capecitabine. Clinicians may add 1 year of adjuvant pertuzumab to trastuzumab-based combination chemotherapy in patients with high-risk, early-stage, HER2-positive breast cancer. Clinicians may use extended adjuvant therapy with neratinib to follow trastuzumab in patients with early-stage, HER2-positive breast cancer. Neratinib causes substantial diarrhea, and diarrhea prophylaxis must be used. Additional information can be found at www.asco.org/breast-cancer-guidelines .

Purpose: We sought to evaluate whether pathologic nodal response was predictive of outcomes in women aged ≤40 years with breast cancer treated with neoadjuvant chemotherapy (NAC). Methods: A total of 220 patients treated with NAC between 1991 and 2015 were retrospectively reviewed. Pathologic complete response (pCR) was defined as no evidence of residual invasive tumor in the breast and lymph nodes (LNs) (ypT0/Tis ypN0); partial response if there was no tumor in the LNs but residual tumor in the breast (ypT+ ypN0) or residual tumor in the LNs (ypT0/Tis ypN+); and limited response if there was residual tumor in both the breast and the LNs (ypT+ ypN+). Kaplan-Meier and Cox proportional hazards analyses were performed to identify factors predictive for overall survival (OS). Results: A total of 155 patients were included. Following NAC, 39 patients (25.2%) achieved pCR, 57 (36.8%) achieved a partial response (either ypT+ ypN0 or ypT0/Tis ypN+), and 59 (38.1%) had a limited response. A total of 22 patients (14.2%) experienced local failure, 20 (12.9%) experienced regional failure, and 59 (38.1%) experienced distant failure. Median OS for patients who achieved pCR was not reached, and was significantly worse for patients who had residual disease in the breast and/or LNs (P

Purpose The mammalian target of rapamycin inhibitor everolimus targets aberrant signaling through the PI3K/AKT/mammalian target of rapamycin pathway, a mechanism of resistance to anti-estrogen therapy in estrogen receptor (ER)–positive breast cancer. We hypothesized that everolimus plus the selective ER downregulator fulvestrant would be more efficacious than fulvestrant alone in ER-positive metastatic breast cancer resistant to aromatase inhibitor (AI) therapy. Patients and Methods This randomized, double-blind, placebo-controlled, phase II study included 131 postmenopausal women with ER-positive, human epidermal growth factor receptor 2–negative, AI-resistant metastatic breast cancer randomly assigned to fulvestrant (500 mg days 1 and 15 of cycle 1, then day 1 of cycles 2 and beyond) plus everolimus or placebo. The study was designed to have 90% power to detect a 70% improvement in median progression-free survival from 5.4 months to 9.2 months. Secondary end points included objective response and clinical benefit rate (response or stable disease for at least 24 weeks). Prophylactic corticosteroid mouth rinses were not used. Results The addition of everolimus to fulvestrant improved the median progression-free survival from 5.1 to 10.3 months (hazard ratio, 0.61 [95% CI, 0.40 to 0.92]; stratified log-rank P = .02), indicating that the primary trial end point was met. Objective response rates were similar (18.2% v 12.3%; P = .47), but the clinical benefit rate was significantly higher in the everolimus arm (63.6% v 41.5%; P = .01). Adverse events of all grades occurred more often in the everolimus arm, including oral mucositis (53% v 12%), fatigue (42% v 22%), rash (38% v 5%), anemia (31% v. 6%), diarrhea (23% v 8%), hyperglycemia (19% v 5%), hypertriglyceridemia (17% v 3%), and pneumonitis (17% v 0%), although grade 3 to 4 events were uncommon. Conclusion Everolimus enhances the efficacy of fulvestrant in AI-resistant, ER-positive metastatic breast cancer.

Background: Talazoparib (TALA; 1 mg/d) was well tolerated and exhibited promising antitumor activity in ABRAZO, a 2-cohort, 2-stage, open-label phase 2 study (NCT02034916) in patients (pts) with locally advanced or metastatic breast cancer and gBRCA1/2 mutations following platinum-based therapy (cohort 1 [C1]) or ≥3 platinum-free cytotoxic-based regimens (cohort 2 [C2]). This analysis evaluates health-related quality of life (QoL) for both cohorts. Methods: QoL was assessed on day 1 (baseline) and every 6 weeks for the initial 24 weeks and every 12 weeks thereafter, or sooner if progression was clinically suspected, using the EORTC QLQ-C30 and its breast cancer module, QLQ-BR23. For all scales, results were summarized using descriptive statistics for each cohort and at each time point, based on Characters (max 3400 including title, body and table [including spaces]): 3363 No abbreviations in title; title sentence case; define acronyms; no figures Category: Psychosocial, QOL, and Educational Aspects – Other 2 observed values and changes from baseline (clinically meaningful defined as ≥10-point change from baseline). Time to deterioration (TTD; defined as ≥10-point decrease in global health status [GHS]/functional scales or increase in symptom scales) analyses using survival analysis methods were carried out on the GHS/functional scales of QLQ-C30 and symptom scales of QLQ-BR23. Results:GHS was maintained from baseline across all time points for both C1 and C2 except at week 24 in C2, when a statistically significant but not clinically meaningful improvement in GHS was observed. In C1, statistically significant and clinically meaningful improvement was observed at specific time points in 4 functional scales (body image, week 6; sexual functioning, week 24; sexual enjoyment, week 36; and future perspective, weeks 6, 18, and 24) and in 3 symptom scales (dyspnea, week 24; insomnia, week 24; and breast symptoms, weeks 6 and 36). Statistically significant and clinically meaningful deterioration in C1 was observed in 2 functional scales (emotional functioning, week 12 and end of treatment, and role functioning, end of treatment) and in 1 symptom scale (fatigue, week 6). In C2, statistically significant and clinically meaningful improvement was observed at specific time points in 4 functional scales (role functioning, week 24; social functioning, week 24; sexual enjoyment, week 18; and future perspective, weeks 6, 12, and 18) and in 5 symptom scales (nausea/vomiting, week 18; pain, weeks 12, 18, and 24; insomnia, week 24; breast symptoms, weeks 12 and 18; and arm symptoms, week 48). For C2, no statistically significant and clinically meaningful deterioration was observed for any functional or symptoms scales across all time points, except in the dyspnea symptom scale at week 18. For C1 and C2, the median (95% confidence interval) TTD of GHS was 2.8 (2.1-3.0) and 5.5 (4.2-5.7) months, respectively. The median TTD for all QLQ-C30 functional scales for C1 and C2 ranged 2.1-3.1 and 4.2-5.6 months, respectively; the median TTD for all QLQ-BR23 symptoms scales ranged 2.6-4.0 and 4.2-5.6 months, respectively. Conclusions: The QoL of TALA-treated patients during ABRAZO was maintained. QoL is being evaluated among atients with germline BRCA1/2 mutated advanced BC treated with TALA vs physician's choice chemotherapy in the phase 3 EMBRACA trial (NCT01945775). Citation Format: Hurvitz SA, Turner NC, Telli ML, Rugo HS, Mailliez A, Ettl J, Grischke E-M, Mina LA, Balmaña J, Fasching PA, Tudor C, Quek RGW, Hannah AL, Robson ME, Wardley AM. Health-related quality of life during a phase 2 study of talazoparib in patients with advanced breast cancer and germline BRCA1/2 mutations (ABRAZO) [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P5-19-05.

Background: CB-839 is a first-in-class oral highly selective inhibitor of glutaminase (GLS), a mitochondrial enzyme that plays a key role in cancer cell metabolism. Triple negative breast cancer (TNBC) has high GLS expression and demonstrates high glutamine utilization and glutamine dependence in clinical and preclinical studies. CB-839 has monotherapy antitumor activity in vitro and in vivo in preclinical models of TNBC, and also demonstrates synergistic anti-cancer activity with the standard of care agent paclitaxel (Pac). In an ongoing Phase 1 study, CB-839 combined with Pac (Pac-CB) is being evaluated in patients (pts) with metastatic TNBC. We previously reported that Pac-CB was well-tolerated and active in heavily pre-treated TNBC pts, including those previously refractory to taxane treatment for metastatic disease. We report here updated results from this ongoing study. Methods: Pts with refractory metastatic TNBC (prior taxane therapy allowed) received escalating doses of CB-839 (400-800 mg BID) in combination with full dose Pac of 80 mg/m2 Days 1, 8, 15 every 28 days. After demonstration of safety and tolerability, an expansion cohort was opened at the CB-839 recommended phase 2 dose of 800 mg PO BID. Results: As of the May 2017 data cut, 45 pts have enrolled across the dose escalation and expansion cohorts (7 pts at 400 mg, 12 at 600 mg, and 26 at 800 mg). 15 pts (33%) have received ≥5 prior lines of systemic therapy for metastatic disease (median 3 prior lines), and 39 pts (87%) have received prior taxane therapy. The Pac-CB regimen has been well tolerated with the most frequent treatment-related Grade ≥3 AEs being neutropenia (24%), anemia (7.6%), fatigue (2.6%), WBC decreased (2.6%), and peripheral neuropathy (2.6%). At CB-839 doses ≥600 mg BID (n=27 RECIST-evaluable), the ORR has been 22% and disease control rate (DCR=CR+PR+SD) 59%; in the subgroup of pts refractory to previous taxane therapy (n=19) the ORR has been 21% (4 pts) and DCR 47% (9 pts). The highest ORR in this study has been seen in pts of African ancestry (AA, n=11 RECIST evaluable) with an ORR of 36% (4 pts) and DCR 55% (6 pts), with all 4 AA responders being refractory to prior taxane treatment for advanced/metastatic disease. Conclusions: TNBC has elevated glutamine metabolism that requires mitochondrial GLS. In TNBC pts with heavy pretreatment and previous taxane exposure, the combination of CB-839 with Pac has demonstrated clinical activity including a 21% ORR in pts refractory to taxane. Notably, in patients of African ancestry, a population reported to have especially high glutamine utilization in TNBC tumors, the encouraging ORR of 36% suggests a potential genetic association with treatment response. The Pac-CB regimen has been well tolerated in late line TNBC pts, including a Gr 3 neuropathy signal of only 2.6%. A Phase 2 study, CX-839-007, has been initiated to further evaluate the activity and safety of Pac-CB in pts with TNBC, including defined cohorts of pts with 1st line and 3rd line+ metastatic disease in pts of African and non-African ancestry. Responses in relation to genetic background, molecular subtype of TNBC and glutamine biology will be studied. Citation Format: Kalinsky K, Harding JJ, DeMichele A, Infante JR, Gogineni K, Owonikoko TK, Isakoff S, Iliopoulos O, Patel MR, Munster P, Telli ML, Jenkins Y, Fiji GP, Whiting SH, Meric-Bernstam F. Phase 1 study of CB-839, a first-in-class oral inhibitor of glutaminase, in combination with paclitaxel in patients with advanced triple negative breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr PD3-13.

Background: ATR is a critical regulator of the cellular response to replication stress; it signals DNA damage repair, mediated through homologous recombination. Many cancers depend on ATR to survive DNA damage. M6620 is a potent, selective inhibitor of ATR that augments the anticancer activity of cisplatin in preclinical triple-negative breast cancer (TNBC) models. Given the high prevalence of TP53 mutations in TNBC and limited platinum responsiveness in patients lacking a BRCA1/2 mutation, this study was designed to evaluate the safety and efficacy of M6620 in combination with cisplatin in an expansion cohort of patients with BRCA1/2 wild-type advanced/metastatic TNBC. Methods: Eligible patients had advanced/metastatic ER-, PR-, and HER2- breast cancer with 0-2 prior non–platinum-based therapies and measurable disease per RECIST 1.1. First line patients were eligible if relapse occurred ≥3 months after prior (neo)adjuvant chemotherapy. Of a maximum 50 patients planned for enrollment, ≥30 were required to have BRCA1/2 germline wild-type status and basaloid molecular subtype tumors on central testing. Patients received intravenous cisplatin 75 mg/m2 on day 1 with intravenous M6620 140 mg/m2 on days 2 and 9 of each 21-day cycle. In patients intolerant of cisplatin or at investigator's discretion, cisplatin could be switched to carboplatin AUC 5 with M6620 90 mg/m2. Results: At the time of abstract submission, 35 female patients were enrolled in this study; 18 patients with confirmed BRCA1/2 wild-type and basaloid metastatic TNBC who received ≥1 cycle of study drug and had ≥1 baseline scan and ≥1 on-treatment scan at the time of the data cut were included in the primary efficacy analysis. Median progression-free survival (PFS) was 4.1 months (90% CI, 1.6-6.9 months). PFS was ≥ 6 months in 2 patients and ≥ 3 months in 8 patients. Preliminary unconfirmed objective response [complete response or partial response (PR)] was observed in 38.9% (90% CI, 19.9%-60.8%) of patients. All 7 patients with preliminary objective response had PR as best overall response; the longest duration of response was 183 days. Response was ongoing in 4 patients with PR at the time of data cutoff. Grade ≥3 related treatment-emergent adverse events occurred in 16 of 35 patients: neutropenia (n=8), anemia (n=5), vomiting (n=4), nausea (n=3), and, in 1 patient each, thrombocytopenia, neutrophil count decreased, platelet count decreased, hypokalemia, generalized weakness, rigors, and acute kidney injury. Conclusions: Combination of M6620 and cisplatin shows encouraging antitumor activity and tolerability in patients with advanced/metastatic TNBC. The study is ongoing; updated safety and efficacy results will be presented. Citation Format: Telli ML, Lord S, Dean E, Abramson V, Arkenau H-T, Murias C, Becerra C, Tang R, Penney MS, Pollard J, Conboy G, Fields SZ, Shapiro G, Tolaney SM. ATR inhibitor M6620 (formerly VX-970) with cisplatin in metastatic triple-negative breast cancer: Preliminary results from a phase 1 dose expansion cohort (NCT02157792) [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 OT2-07-07.

Background: Talazoparib (TALA) is a dual-mechanism poly (ADP-ribose) polymerase (PARP) inhibitor that traps PARP on DNA. Efficacy results of this phase 2 trial were previously presented (Turner et al, ASCO 2017, abstract 1007). This study included sparse pharmacokinetic (PK) sampling for patients through cycle 4 of therapy. Exploratory analyses included assessment of exposure versus parameters of efficacy and safety. Methods: ABRAZO (NCT02034916) was a parallel-cohort, open-label phase 2 study of TALA (1 mg/d) following (i) platinum-based therapy (cohort 1) or (ii) ≥3 platinum-free cytotoxic-based regimens (cohort 2) in patients with locally advanced or metastatic breast cancer and germline BRCA1/2 mutation. Sparse PK sampling was performed on day 1 of cycles 1-4, consisting of a predose sample collected ≤60 minutes prior to dosing and 2 postdose samples collected ≥30 minutes after dosing (time of food ingestion prior to the dose was collected). The collection times of the 2 postdose samples were separated by ≥2 hours. Efficacy parameters included radiographic progression-free survival (rPFS) by central review and objective response rate (ORR). Safety parameters included incidence of overall adverse events (AEs) and grade ≥3 AEs. Individual AUCs (area under concentration-time curves) for exposure-response analyses were predicted by population PK analyses. Results: Patients were divided into AUC tertiles: low (median, 109.0 ng*hr/mL; n=27), intermediate (median, 170.8 ng*hr/mL; n=27), and high (median, 219.2 ng*hr/mL; n=27). Median rPFS was 5.3 months (95% confidence interval [CI], 3.1, 8.3) in the lowest AUC tertile, 5.6 months (95% CI, 3.7, 8.4) in the intermediate AUC tertile, and 5.3 months (95% CI, 3.9, 5.6) in the highest AUC tertile. The ORR was 22.2% (95% CI, 8.6, 42.3) in the lowest AUC tertile, 25.9% (95% CI, 11.1, 46.3) in the intermediate AUC tertile, and 37.0% (95% CI, 19.4, 57.6) in the highest AUC tertile. AEs of any grade were reported in 11 patients (40.7%) in the lowest AUC tertile, 21 patients (77.8%) in the intermediate AUC tertile, and 22 patients (81.5%) in the highest AUC tertile. Grade ≥3 AEs were reported in 8 patients (29.6%) in the lowest AUC tertile and in 18 patients (66.7%) in the intermediate and highest AUC tertiles. The most common AEs in all 3 exposure tertiles were anemia, thrombocytopenia, and neutropenia. Conclusions: Median rPFS did not change with increasing systemic exposure. There may be a trend to higher ORR in patients with highest systemic exposure. A larger percentage of patients experienced AEs with elevated systemic exposure. Increased response rates with greater exposure does not translate to improved rPFS. These results should be interpreted with caution due to the low patient numbers in each cohort. Citation Format: Telli ML, Turner NC, Mailliez A, Ettl J, Grischke E-M, Mina LA, Balmaña J, Hurvitz SA, Wardley AM, Fasching PA, Tudor C, Nguyen L, Hannah AL, Robson ME, Rugo HS. ABRAZO: Exposure-efficacy and -safety analyses of breast cancer patients with germline BRCA1/2 mutations receiving talazoparib in a phase 2 open-label 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 P1-14-03.

Purpose: Based on promising preclinical data, we conducted a single-arm phase II trial to assess the clinical benefit rate (CBR) of neratinib, defined as complete/partial response (CR/PR) or stable disease (SD) ≥24 weeks, in HER2mut nonamplified metastatic breast cancer (MBC). Secondary endpoints included progression-free survival (PFS), toxicity, and circulating tumor DNA (ctDNA) HER2mut detection. Experimental Design: Tumor tissue positive for HER2mut was required for eligibility. Neratinib was administered 240 mg daily with prophylactic loperamide. ctDNA sequencing was performed retrospectively for 54 patients (14 positive and 40 negative for tumor HER2mut). Results: Nine of 381 tumors (2.4%) sequenced centrally harbored HER2mut (lobular 7.8% vs. ductal 1.6%; P = 0.026). Thirteen additional HER2mut cases were identified locally. Twenty-one of these 22 HER2mut cases were estrogen receptor positive. Sixteen patients [median age 58 (31–74) years and three (2–10) prior metastatic regimens] received neratinib. The CBR was 31% [90% confidence interval (CI), 13%–55%], including one CR, one PR, and three SD ≥24 weeks. Median PFS was 16 (90% CI, 8–31) weeks. Diarrhea (grade 2, 44%; grade 3, 25%) was the most common adverse event. Baseline ctDNA sequencing identified the same HER2mut in 11 of 14 tumor-positive cases (sensitivity, 79%; 90% CI, 53%–94%) and correctly assigned 32 of 32 informative negative cases (specificity, 100%; 90% CI, 91%–100%). In addition, ctDNA HER2mut variant allele frequency decreased in nine of 11 paired samples at week 4, followed by an increase upon progression. Conclusions: Neratinib is active in HER2mut, nonamplified MBC. ctDNA sequencing offers a noninvasive strategy to identify patients with HER2mut cancers for clinical trial participation. Clin Cancer Res; 23(19); 5687–95. ©2017 AACR.

Purpose: In germline BRCA1 or BRCA2 (BRCA1/2) mutation carriers, restoration of tumor BRCA1/2 function by a secondary mutation is recognized as a mechanism of resistance to platinum and PARP inhibitors, primarily in ovarian cancer. We evaluated this mechanism of resistance in newly diagnosed patients with BRCA1/2-mutant breast cancer with poor response to neoadjuvant platinum-based therapy. Experimental Design: PrECOG 0105 was a phase II neoadjuvant study of gemcitabine, carboplatin, and iniparib in patients with stage I–IIIA triple-negative or BRCA1/2 mutation–associated breast cancer (n = 80). All patients underwent comprehensive BRCA1/2 genotyping. For mutation carriers with moderate or extensive residual disease after neoadjuvant therapy, BRCA1/2 status was resequenced in the residual surgical breast tumor tissue. Results: Nineteen patients had a deleterious germline BRCA1/2 mutation, and four had moderate residual disease at surgery. BRCA1/2 sequencing of residual tissue was performed on three patients. These patients had BRCA1 1479delAG, 3374insGA, and W1712X mutations, respectively, with LOH at these loci in the pretreatment tumors. In the first case, a new BRCA1 mutation was detected in the residual disease. This resulted in a 14–amino acid deletion and restoration of the BRCA1 reading frame. A local relapse biopsy 4 months later revealed the identical reversion mutation, and the patient subsequently died from metastatic breast cancer. Conclusions: We report a BRCA1 reversion mutation in a patient newly diagnosed with triple-negative breast cancer that developed over 18 weeks of platinum-based neoadjuvant therapy. This was associated with poor therapy response, early relapse, and death. Clin Cancer Res; 23(13); 3365–70. ©2017 AACR.

These NCCN Guidelines Insights highlight the important updates/changes to the surgical axillary staging, radiation therapy, and systemic therapy recommendations for hormone receptor-positive disease in the 1.2017 version of the NCCN Guidelines for Breast Cancer. This report summarizes these updates and discusses the rationale behind them. Updates on new drug approvals, not available at press time, can be found in the most recent version of these guidelines at NCCN.org.

Since the identification of the BRCA1 and BRCA2 genes over two decades ago, considerable progress has been made in elucidating the role of defective DNA repair in the pathogenesis of triple-negative breast cancer (TNBC). Here, we discuss the significance of recent advances in our understanding of homologous recombination (HR) deficiency, emerging HR deficiency biomarkers, and novel clinical approaches for exploiting HR deficiency in TNBC. Recent preclinical and clinical studies have implicated homologous recombination (HR) pathway defects as viable targets in TNBC. New treatment strategies have emerged to exploit defective HR pathways, including platinum salts and poly (ADP-ribose) polymerase (PARP) inhibitors. Early clinical experience with these agents has been promising, though response rates are variable and resistance through a variety of mechanisms can occur. Platforms to identify signatures of HR deficiency have gained increased attention and are being investigated as a tool for guiding treatment selection. While a HR-deficient phenotype is increasingly recognized as being present in a significant portion of TNBCs, it is only recently that these advances are beginning to be translated into the clinical setting. Clinical studies are ongoing that will help to define the role of therapies targeting defective DNA repair pathways and biomarkers of HR deficiency in TNBC.

Background: CB-839 is a first-in-class highly selective inhibitor of GLS, a key enzyme in the utilization of glutamine by cancer cells. TNBC has high GLS expression and is very dependent upon GLS-mediated conversion of glutamine to glutamate for tumor cell growth. CB-839 has antitumor activity in vitro and in vivo in preclinical models of TNBC. Recent studies demonstrate that glutamine utilization can contribute to resistance to paclitaxel, a therapy frequently used to treat TNBC patients. Paclitaxel sensitivity is dependent on down-regulation of the glutamine transporter, SLC1A5, and over-expression of SLC1A5 causes paclitaxel resistance. Consistent with these observations, inhibition of glutamine metabolism with CB-839 has demonstrated strong antitumor activity in combination with paclitaxel. CX-839-001 is an ongoing Phase 1 trial of CB-839 as monotherapy and in combination with approved agents. We previously reported pharmacodynamic studies demonstrating robust inhibition of GLS in pt blood and tumors and excellent tolerability of CB-839 monotherapy in a variety of tumor types including TNBC. In light of the preclinical rationale and monotherapy tolerability a combination arm was opened testing CB-839 with paclitaxel (Pac-CB) in patients with advanced TNBC. We report here updated results on the Pac-CB dose escalation and expansion cohorts. Methods: Patients with refractory advanced/metastatic TNBC (prior taxane therapy allowed) received escalating doses of CB-839 (400-800 mg BID) in combination with a fixed weekly Pac dose of 80 mg/m2 Days 1, 8, 15 of a 28 day cycle. Upon demonstration of safety and tolerability, an expansion cohort of TNBC pts was opened. Results: To date, 15 pts have received Pac-CB at three dose levels of CB-839: 7 pts at 400 mg BID, 5 at 600 mg BID and 3 at 800 mg BID with the latter dose level not completed. 40% of enrolled patients have received >5 prior lines of systemic therapy for adv/met disease, and 10 pts have received prior taxane therapy including 5 in the adv/met setting. The Pac-CB combination has been well tolerated with one DLT during dose escalation (G4 neutropenia at 400 mg BID) and a low rate of dose reductions (2 for Pac and 1 for CB-839). Of 15 pts, the best overall response rate (BORR, see Table) has been PR in 20% (3 pts), SD in 47% (7 pts) and PD in 33% (5 pts) with 5 patients remaining on study. At doses ≥600 mg BID (n=8) the BORR is 38% (3 pts), and disease control rate (CR + PR + SD) is 88% (7 pts). All 3 pts with PRs have received prior Pac, including 2 pts with disease that was refractory to Pac in the advanced/metastatic setting. Conclusions: The Pac-CB combination has been well tolerated and has demonstrated clinical activity in heavily pre-treated pts with TNBC. At doses ≥600 mg BID, BORR has been 38% and DCR 88%. Notably, PRs have occurred in pts with prior Pac therapy, including 2 pts with Pac-refractory disease in the adv/met setting. Updated data on the escalation and expansion cohorts will be presented. Dose LevelTotal400 mg BID600 mg BID800 mg BIDRECIST Response Evaluable (N)15753PR3 (20%)02 (40%)1 (33%)SD7 (47%)3 (43%)2 (40%)2 (67%)DCR (CR+PR+SD)10 (67%)3 (43%)4 (80%)3 (100%)PD5 (33%)4 (57%)1 (20%)0 Citation Format: DeMichele AM, Harding JJ, Telli ML, Münster P, McKay RR, Iliopoulos O, Whiting S, Orford KW, Bennett MK, Mier JW, Owonikoko TK, Patel MR, Kalinsky K, Carvajal RD, Infante JR, Merit-Bernstam F. Phase 1 study of CB-839, a small molecule inhibitor of glutaminase (GLS), in combination with paclitaxel (Pac) in patients (its) with triple negative breast cancer (TNBC) [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P6-11-05.

Background: Poly(ADP-ribose) polymerase (PARP) inhibitors block DNA damage repair and may thereby enhance the clinical activity of DNA-damaging chemotherapy. Homologous recombination is defective in BRCA1/2-mutated tumors, leading to more error-prone mechanisms of DNA repair and increased sensitivity to PARP inhibition. V is a potent PARP inhibitor that enhances the antitumor activity of platinum agents in preclinical models. This phase 2 trial (NCT01506609) investigated the safety and efficacy of V+C/P or V+ temozolomide (TMZ) vs Plc+C/P in pts with locally recurrent or metastatic breast cancer harboring a BRCA1 or BRCA2 mutation. Results of the V+C/P and Plc+C/P arms are presented; V+TMZ results will be presented separately. Methods: Pts ≥18 years with histologically confirmed locally recurrent or metastatic breast cancer were randomized 1:1:1 to: 1) V 40 mg BID D1–7+TMZ, 28-D cycle; 2) V 120 mg BID D1–7+C AUC 6, D3 and P 175 mg/m2, D3, 21-D cycle; or 3) Plc BID D1–7+C/P. Key eligibility criteria included deleterious BRCA1/2 mutation, ≤2 prior chemotherapies for metastatic disease, no prior platinum agent, and no CNS metastases. Randomization was stratified by hormone receptor status, prior cytotoxic therapy, and ECOG PS. The primary endpoint was progression-free survival (PFS) per RECIST 1.1 of each V arm vs Plc+C/P by independent review. Primary analysis occurred at the 112th PFS event in the V+C/P and Plc+C/P arms. Overall survival (OS), objective response rate (ORR), tolerability, and quality of life were also evaluated. Results: A total of 196 pts (193 BRCA+ per central lab) were randomized to receive double-blinded V+C/P (n=97) or Plc+C/P (n=99). Baseline demographics and disease characteristics were balanced across all treatment arms. Median study drug exposure was 10 cycles for Plc+C/P and 12 cycles for V+C/P. The V+C/P arm demonstrated numeric improvements for both PFS and OS compared to the Plc+C/P arm; improvement in ORR was statistically significant (Table 1). There was no meaningful increase of toxicity with addition of V. The most common treatment-emergent adverse events (AEs) with Plc+C/P or V+C/P were neutropenia (74%/74%), thrombocytopenia (70%/71%), and nausea (58%/71%). Grade ≥3 AEs in ≥30% of pts were neutropenia (55%/56%) and thrombocytopenia (26%/31%), respectively. There was no difference in the use of G-CSF with addition of V. Significant improvements in fatigue, pain, and insomnia (all P Conclusions: This is the first randomized phase 2 trial of a PARP inhibitor in combination with platinum-based therapy for treatment of BRCA1/2-mutated advanced breast cancer. V+C/P demonstrated significantly higher ORR and symptom improvement compared to Plc+C/P, with nonsignificant trends for improved OS and PFS. Phase 3 trials are ongoing. Table 1Efficacy (ITT population – BRCA mutation)Plc+C/P, n=98V+C/P, n=95HR (95% CI); P valuePFS(mo, 95% CI)12.3 (9.3–14.5)14.1 (11.5–16.2)0.789 (0.536–1.162); 0.231OS (mo, 95% CI)25.0 (18.1–34.8)28.5 (22.4–NR)0.725 (0.468–1.121); 0.148ORR, % (95% CI)61.3 (49.7–71.9)77.8 (66.4–86.7)P=0.027 Citation Format: Han HS, Diéras V, Robson ME, Palácová M, Marcom PK, Jager A, Bondarenko I, Citrin D, Campone M, Telli ML, Domchek SM, Friedlander M, Kaufman B, Ratajczak C, Coates A, Bonnet P, Qin Q, Qian J, Giranda VL, Shepherd SP, Isakoff SJ, Puhalla S. Efficacy and tolerability of veliparib (V; ABT-888) in combination with carboplatin (C) and paclitaxel (P) vs placebo (Plc)+C/P in patients (pts) with BRCA1 or BRCA2 mutations and metastatic breast cancer: A randomized, phase 2 study [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr S2-05.

Background: TNBC patients with homologous recombination (HR) deficient tumors have significantly higher pathologic complete response (pCR, ypT0/is ypN0) rates when treated with platinum-based chemotherapy. TILs are prognostic and predictive of chemotherapy benefit in TNBC. Interestingly, recent data suggests that HR deficient TNBCs and BRCA1/2 mutant ovarian cancers may be enriched for immune cell infiltration. Thus, we performed a pooled analysis of 5 phase II studies that included patients with TNBC treated with neoadjuvant platinum-based chemotherapy to evaluate the association of TILs with HR deficiency status and tumor BRCA1/2 mutation status. Methods: 166 patients with TNBC and known HR deficiency status from the following clinical trials were available for analysis: PrECOG 0105 (N=72), NCT00580333 (N=32), NCT01372579 (N=26), TBCRC 008 (N=18) and NCT00148694 (N=18). Neoadjuvant chemotherapy regimens included 1) carboplatin, gemcitabine, iniparib, 2) cisplatin with or without bevacizumab 3) carboplatin, eribulin, 4) carboplatin, nab-paclitaxel, with or without vorinostat. HR deficiency status was defined as a high HRD score (42 or higher) and/or presence of a BRCA1/2 tumor mutation (tBRCA). Digitized pre-treatment core biopsy H&E sections were reviewed and scored by two blinded expert breast cancer pathologists using the international TIL working group guidelines. The density (%) of both intratumoral TILs (iTILs) and stromal TILs (sTILs) was recorded by deciles (n=122 thus far, additional cases to be included in final analysis). Results: Among 122 patients, pCR was achieved in 36 patients (29.5%) and 71 tumors (58.2%) were HR deficient. In total, 24 patients (19.7%) patients had a deleterious BRCA1/2 mutation. Among all tumors, iTIL and sTIL median densities were 0% (range 0-20) and 10% (range 0-80), respectively, and were not statistically different in HR deficient versus non-deficient tumors (iTIL p=0.746; sTIL p=0.159). The same absent association was observed for tBRCA mutation status (iTIL p=0.607; sTIL p=0.315) and binary HRD score (iTIL p=0.879; sTIL p=0.364). Updated results with additional cases scored for TILs will be reported at time of presentation. Additional analyses assessing the relationship between TILs and pCR/residual cancer burden adjusting for HRD status and other clinical variables will also be included at the time of presentation. Conclusion: Several previous studies have reported that TILs are significantly associated with response to standard chemotherapy regimens when given in the neoadjuvant setting. Measures of genomic instability and DNA repair deficiency, including HRD, have been shown to be robust predictors of response to chemotherapy, including platinum containing regimens. It is unclear if TILs will be predictive in a similarly robust way for response to platinum-containing regimens. Results of this study suggest TIL density and HR deficiency status may be independent and non-overlapping. Final analysis including additional cases will be included in the final presentation.Background: TNBC patients with homologous recombination (HR) deficient tumors have significantly higher pathologic complete response (pCR, ypT0/is ypN0) rates when treated with platinum-based chemotherapy. TILs are prognostic and predictive of chemotherapy benefit in TNBC. Interestingly, recent data suggests that HR deficient TNBCs and BRCA1/2 mutant ovarian cancers may be enriched for immune cell infiltration. Thus, we performed a pooled analysis of 5 phase II studies that included patients with TNBC treated with neoadjuvant platinum-based chemotherapy to evaluate the association of TILs with HR deficiency status and tumor BRCA1/2 mutation status. Methods: 166 patients with TNBC and known HR deficiency status from the following clinical trials were available for analysis: PrECOG 0105 (N=72), NCT00580333 (N=32), NCT01372579 (N=26), TBCRC 008 (N=18) and NCT00148694 (N=18). Neoadjuvant chemotherapy regimens included 1) carboplatin, gemcitabine, iniparib, 2) cisplatin with or without bevacizumab 3) carboplatin, eribulin, 4) carboplatin, nab-paclitaxel, with or without vorinostat. HR deficiency status was defined as a high HRD score (42 or higher) and/or presence of a BRCA1/2 tumor mutation (tBRCA). Digitized pre-treatment core biopsy H&E sections were reviewed and scored by two blinded expert breast cancer pathologists using the international TIL working group guidelines. The density (%) of both intratumoral TILs (iTILs) and stromal TILs (sTILs) was recorded by deciles (n=122 thus far, additional cases to be included in final analysis). Results: Among 122 patients, pCR was achieved in 36 patients (29.5%) and 71 tumors (58.2%) were HR deficient. In total, 24 patients (19.7%) patients had a deleterious BRCA1/2 mutation. Among all tumors, iTIL and sTIL median densities were 0% (range 0-20) and 10% (range 0-80), respectively, and were not statistically different in HR deficient versus non-deficient tumors (iTIL p=0.746; sTIL p=0.159). The same absent association was observed for tBRCA mutation status (iTIL p=0.607; sTIL p=0.315) and binary HRD score (iTIL p=0.879; sTIL p=0.364). Updated results with additional cases scored for TILs will be reported at time of presentation. Additional analyses assessing the relationship between TILs and pCR/residual cancer burden adjusting for HRD status and other clinical variables will also be included at the time of presentation. Conclusion: Several previous studies have reported that TILs are significantly associated with response to standard chemotherapy regimens when given in the neoadjuvant setting. Measures of genomic instability and DNA repair deficiency, including HRD, have been shown to be robust predictors of response to chemotherapy, including platinum containing regimens. It is unclear if TILs will be predictive in a similarly robust way for response to platinum-containing regimens. Results of this study suggest TIL density and HR deficiency status may be independent and non-overlapping. Final analysis including additional cases will be included in the final presentation. Citation Format: Telli ML, Badve S, Vinayak S, Silver DP, Isakoff SJ, Kaklamani VG, Gradishar WJ, Stearns V, Connolly RM, Ford JM, Adams S, Garber JE, Evans B, Timms K, Wenstrup R, Richardson AL. Evaluation of tumor infiltrating lymphocytes (TILs) and their association with homologous recombination deficiency and BRCA1/2 mutation status in triple-negative breast cancer (TNBC): A pooled analysis [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P6-09-09.

Veliparib is an orally administered poly(ADP-ribose) polymerase inhibitor that is being studied in Phase I–III clinical trials, including Phase III studies in non-small-cell lung cancer, ovarian cancer and breast cancer. Tumor cells with deleterious BRCA1 or BRCA2 mutations are deficient in homologous recombination DNA repair and are intrinsically sensitive to platinum therapy and poly(ADP-ribose) polymerase inhibitors. We describe herein the design and rationale of a Phase II trial investigating whether the addition of veliparib to temozolomide or carboplatin/paclitaxel provides clinical benefit over carboplatin/paclitaxel with placebo in patients with locally recurrent or metastatic breast cancer harboring a deleterious BRCA1 or BRCA2 germline mutation (Trial registration: EudraCT 2011-002913-12, NCT01506609).

Background and Objective: Trastuzumab (Herceptin)-based chemotherapy regimens play a prominent role in treatments of breast cancer, but a significant number of patients develop cardiac disfunction during the therapy. In this study, we examined whether human induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) could serve as an effective platform to study this particular cardiotoxicity. Methods and Results: We assessed the effects of trastuzumab on structural and functional properties in three control iPSC-CMs from healthy individuals and found that clinically relevant doses of trastuzumab (1 μM) significantly reduced the contraction velocity (-7.4%, P < 0.01) and calcium amplitude (-14.1%, P < 0.01) in iPSC-CMs without inducing cardiomyocyte death or sarcomeric structural abnormalities. RNA-sequencing analysis revealed mitochondrial dysfunction and altered cardiac energy metabolism pathway as primary causes of this cardiotoxicity. Subsequently, we found that significant reductions in basal, maximal, and ATP-linked oxygen consumption (-19.8%, -10.7%, and -19.0%, respectively, P < 0.01 for all) and cellular ATP content (-10.3%, P < 0.01) in iPSC-CMs after trastuzumab treatment. Next, we recruited seven breast cancer patients with trastuzumab therapy, including five patients diagnosed with trastuzumab-induced cardiac dysfunction and generated iPSCs from these patients. We found that contraction velocity and maximal oxygen consumption were more severely reduced by trastuzumab in iPSC-CMs generated from patients who experienced severe cardiac dysfunction from trastuzumab therapy, compared to iPSC-CMs generated from patients who did not experience cardiac dysfunction (-16.6% vs. -1.4%, and -29.4% vs. -3.7%, respectively, P < 0.01 for all). Lastly, we demonstrated that metabolic modulation with AMPK activators, such as metformin, could avert the detrimental effects of trastuzumab in iPSC-CMs. Conclusion: Our results indicate that human iPSC-CM model can recapitulate the clinical phenotype of trastuzumab-induced cardiac dysfunction, and therefore targeting altered metabolism may be a promising therapeutic approach for treating this cardiotoxicity.

Over a century ago, it was reported that immunization with embryonic/fetal tissue could lead to the rejection of transplanted tumors in animals. Subsequent studies demonstrated that vaccination of embryonic materials in animals induced cellular and humoral immunity against transplantable tumors and carcinogen-induced tumors. Therefore, it has been hypothesized that the shared antigens between tumors and embryonic/fetal tissues (oncofetal antigens) are the key to anti-tumor immune responses in these studies. However, early oncofetal antigen-based cancer vaccines usually utilize xenogeneic or allogeneic embryonic stem cells or tissues, making it difficult to tease apart the anti-tumor immunity elicited by the oncofetal antigens vs. graft-vs.-host responses. Recently, one oncofetal antigen-based cancer vaccine using autologous induced pluripotent stem cells (iPSCs) demonstrated marked prophylactic and therapeutic potential, suggesting critical roles of oncofetal antigens in inducing anti-tumor immunity. In this review, we present an overview of recent studies in the field of oncofetal antigen-based cancer vaccines, including single peptide-based cancer vaccines, embryonic stem cell (ESC)- and iPSC-based whole-cell vaccines, and provide insights on future directions.

Background: Molecular targeted chemotherapies have been shown to significantly improve the outcomes of patients who have cancer, but they often cause cardiovascular side effects that limit their use and impair patients’ quality of life. Cardiac dysfunction induced by these therapies, especially trastuzumab, shows a distinct cardiotoxic clinical phenotype in comparison to the cardiotoxicity induced by conventional chemotherapies. Methods: We used the human induced pluripotent stem cell–derived cardiomyocyte (iPSC-CM) platform to determine the underlying cellular mechanisms in trastuzumab-induced cardiac dysfunction. We assessed the effects of trastuzumab on structural and functional properties in iPSC-CMs from healthy individuals and performed RNA-sequencing to further examine the effect of trastuzumab on iPSC-CMs. We also generated human induced pluripotent stem cells from patients receiving trastuzumab and examined whether patients’ phenotype could be recapitulated in vitro by using patient-specific iPSC-CMs. Results: We found that clinically relevant doses of trastuzumab significantly impaired the contractile and calcium-handling properties of iPSC-CMs without inducing cardiomyocyte death or sarcomeric disorganization. RNA-sequencing and subsequent functional analysis revealed mitochondrial dysfunction and altered the cardiac energy metabolism pathway as primary causes of trastuzumab-induced cardiotoxic phenotype. Human iPSC-CMs generated from patients who received trastuzumab and experienced severe cardiac dysfunction were more vulnerable to trastuzumab treatment than iPSC-CMs generated from patients who did not experience cardiac dysfunction following trastuzumab therapy. It is important to note that metabolic modulation with AMP-activated protein kinase activators could avert the adverse effects induced by trastuzumab. Conclusions: Our results indicate that alterations in cellular metabolic pathways in cardiomyocytes could be a key mechanism underlying the development of cardiac dysfunction following trastuzumab therapy; therefore, targeting the altered metabolism may be a promising therapeutic approach for trastuzumab-induced cardiac dysfunction.

554 Background: TALA is a poly(ADP-ribose) polymerase inhibitor approved as monotherapy for adult pts with g BRCA1/2-mutated HER2-negative locally advanced/metastatic BC. We report biomarker analyses from a phase 2, nonrandomized, single-arm, open-label study (NEOTALA; NCT03499353) evaluating the efficacy and safety of TALA in the neoadjuvant setting for pts with early g BRCA1/2-mutated HER2− BC. Efficacy and safety results are presented separately. Methods: The biomarker analysis population was all pts treated with TALA for whom biomarker results are available. To support molecular eligibility, blood was tested using BRCAnalysis CDx (Myriad Genetics). Baseline tumor tissue was retrospectively tested using FoundationOne CDx, with BRCA1/2 zygosity assessed using somatic-germline-zygosity (SGZ; Sun et al. JCO PO, 2018). Germline mutational status of 14 non- BRCA DNA damage response (DDR) genes was retrospectively assessed in baseline saliva samples using Ambry CustomNext-Cancer. Mutations were defined as known/likely pathogenic/deleterious variants, including copy number alterations (CNAs). Association between mutational status of MYC or RAD21 and primary endpoint pathological complete response (pCR) as per Independent Central Review was investigated with logistic regression. Results: Of 52 evaluable tumor samples from 61 treated pts, 39 (75%) and 13 (25%) pts exhibited BRCA1 and BRCA2 mutations, respectively; 1 (2%) pt exhibited mutations in both genes, and 1 (2%) pt had mutations in neither. BRCA loss of heterozygosity (LOH) was seen in 42/43 (98%) evaluable BRCA-mutant tumors. Of 45 pts evaluable centrally for both germline and tumor, 44/45 (98%) pts exhibited the same BRCA mutation in tumor as originally detected in germline, with the remaining pt exhibiting a g BRCA1 mutation, but lacking a tumor BRCA mutation. None of 49 saliva-evaluable pts exhibited non- BRCA germline DDR mutations. TP53 (51 [98%] pts) was the most frequently mutated gene in tumors. MYC and RAD21 (each 14 [27%] pts) were the most frequent CNAs. No evidence of association between mutational status of MYC or RAD21 and pCR was found (odds ratio=0.39, 95% CI 0.12-2.30). Based on a cutoff of ≥16%, genomic LOH was elevated in 24/27 (89%) tumors evaluable for both gLOH and pCR, precluding assessment of the potential association of gLOH high/low status with pCR. Conclusions: Tumor BRCA mutations were evident in nearly all pts in the biomarker analysis population, with BRCA LOH evident in all but 1 BRCA-mutated tumor. No pts had non- BRCA germline DDR gene mutations; tumor TP53 mutations were near-universal. MYC and RAD21 each exhibited CNAs in 27% of tumors, with no association with pCR. These results support the central role of BRCA mutations in tumor pathobiology in this indication. Clinical trial information: NCT03499353.

TPS1109 Background: PALB2 (Partner and Localizer of BRCA2) plays a critical role in the maintenance of genomic integrity through its role in the Fanconi anemia and homologous recombination DNA repair pathways. Our recently reported phase II clinical trial (Gruber, et al. JCO 2019) showed that talazoparib monotherapy was associated with single agent activity in germline PALB2 (gPALB2) mutation-associated advanced breast cancers. Of 5 patients with a germline PALB2 mutation, all 5 had reduction in target lesions > 20% with 3 of 5 achieving a RECIST 1.1 response. All patients had visceral metastases and were heavily pretreated; one response occurred in a patient with 8 prior lines of therapy for metastatic breast cancer. Clinical activity of the PARP inhibitor olaparib was also demonstrated in breast cancer patients with gPALB2 mutations in the Olaparib Expanded trial (TBCRC 048). Thus, we believe there is significant value in generating additional PARP inhibitor monotherapy data in subjects with advanced PALB2 mutation-associated breast cancer. We propose this phase II trial to better estimate the rate of RECIST 1.1 objective response in this patient population. Methods: This is a single-arm, two-stage, non-randomized study to assess the objective response rate (ORR) of talazoparib monotherapy in patients with PALB2 mutation-associated advanced breast cancer. Eligible subjects will be adults with inoperable locally advanced or metastatic breast cancer with a germline or somatic PALB2 mutation with 0-3 prior therapies for advanced disease. Eligible patients must have a deleterious or suspected deleterious mutation in PALB2 on a CLIA approved commercial germline or next generation sequencing tumor assay. Study treatment is talazoparib 1 mg PO daily. In stage 1, ORR will be assessed after 15 patients; if at least 2 responses are observed then an additional 15 patients will be enrolled; if less than 2 responses are observed the study will be terminated. The primary objective is to evaluate whether talazoparib monotherapy can induce a 30% ORR in subjects with advanced breast cancer associated with a PALB2 mutation. Response will be assessed by RECIST 1.1. Secondary objectives include safety, PFS, clinical benefit rate, and patient-reported quality-of-life. Exploratory endpoints will assess for the presence of PALB2 loss-of-heterozygosity, biallelic mutations, correlation of ctDNA profile with treatment response and the correlation of germline versus somatic mutations with response rate. This trial is currently activated and enrolling at Stanford Cancer Center and it is expected that 4 additional sites will be added. Conclusion: This trial will evaluate gPALB2 as a biomarker for PARP inhibitor monotherapy in advanced or metastatic HER2- breast cancer. Clinical trial information: pending .

505 Background: Talazoparib (TALA) is a poly(ADP-ribose) polymerase inhibitor approved as monotherapy for treating adult patients (pts) with g BRCA1/2-mutated HER2-negative locally advanced or metastatic BC. Methods: This phase 2, non-randomized, single-arm, open-label study (NCT03499353) evaluated the efficacy and safety of TALA in the neoadjuvant setting for pts with early g BRCA1/2-mutated HER2− BC. Primary endpoint was evaluation of pathologic complete response (pCR) as assessed by Independent Central Review (ICR) after completing 24 weeks of neoadjuvant TALA monotherapy 1 mg QD (0.75 mg for moderate renal impairment) followed by surgery. Secondary endpoints included pCR by investigator (INV) and residual cancer burden (RCB) by ICR (RCB: 0 [pCR], I [minimal], II [moderate], III [extensive]). The evaluable population included pts who received at least 80% of the TALA dose prescribed at treatment start and underwent breast surgery and pCR assessment, plus those who progressed before pCR could be assessed. The intent-to-treat (ITT) population included all pts who received at least 1 dose of TALA. Results: Of 61 pts treated with TALA (ITT and safety populations), 48 comprised the evaluable population. All pts had triple-negative BC. 60 pts had adenocarcinoma and 1 had squamous cell histology, with the following staging: I=20, II=27, III=14. Mean age was 44.6 years, mean duration of 4.5 wks since disease onset, mean duration of treatment of 23.3 wks, and mean overall relative dose intensity of 84.5% (ITT population). pCR (assessed by ICR and INV) and RCB (by ICR) for the evaluable and ITT populations are shown in the table below. Ten (16.4%) patients discontinued treatment due to progressive disease. One pt had a disruption of treatment as a result of COVID-19 restrictions, 2 pts for other reasons: to undergo surgery early and consent withdrawal; 9 patients received

Patients with triple-negative breast cancer (TNBC), defined as lacking expression of the estrogen and progesterone receptors (ER/PR) and amplification of the HER2 oncogene, often have a more aggressive disease course than do patients with hormone receptor-positive breast cancer, including higher rates of visceral and central nervous system metastases, early cancer recurrences and deaths. Triple-negative breast cancer is associated with a young age at diagnosis and both African and Ashkenazi Jewish ancestry, the latter due to three common founder mutations in the highly penetrant cancer susceptibility genes BRCA1 and BRCA2 (BRCA1/2). In the past decade, there has been a surge both in genetic testing technology and in patient access to such testing. Advances in genetic testing have enabled more rapid and less expensive commercial sequencing than could be imagined only a few years ago. Massively parallel, next-generation sequencing allows the simultaneous analysis of many different genes. Studies of TNBC patients in the current era have revealed associations of TNBC with mutations in several moderate penetrance breast cancer susceptibility genes, including PALB2, BARD1, BRIP1, RAD51C and RAD51D. Interestingly, many of these genes, like BRCA1/2, are involved in homologous recombination DNA double-stranded repair. In this review, we summarize the current understanding of pathogenic germline gene mutations associated with TNBC and the early detection and prevention strategies for women at risk of developing this high-risk breast cancer subtype. Furthermore, we discuss recent the advances in targeted therapies for TNBC patients with a hereditary predisposition, including the role of poly (ADP-ribose) polymerase (PARP) inhibitors in BRCA1/2 mutation-associated breast cancers.

Background: Poly-ADP-ribose polymerase (PARP) inhibition induces synthetic lethality in tumor cells bearing deleterious mutations in the genes BRCA1/2. Talazoparib (BMN 673) is a novel, dual-mechanism PARP inhibitor that potently inhibits the PARP enzyme and effectively traps PARP on DNA. Talazoparib has shown promising single-agent anti-tumor efficacy in several BRCA1/2 mutation-associated advanced cancers. The efficacy of PARP inhibition in BRCA1/2 wild-type TNBC with HR defects and in breast tumors with mutations in other non-BRCA1/2 HR pathway genes is currently unknown. Trial Design & Eligibility: This Phase 2 trial (TBB) explores the activity of single agent talazoparib in BRCA1/2 wild-type BC patients using an optimal Simon two-stage design. Eligible subjects will be assigned to one of two parallel cohorts: 1) Cohort A: Subjects (n=29) with advanced TNBC with underlying HR defects as assessed by the HRD assay and, 2) Cohort B: Subjects (n=29) with advanced HER2-negative BC with a somatic or germline deleterious mutation in a non-BRCA1/2 HR pathway gene. Gene mutations of interest are: PTEN, PALB2, CHEK2, ATM, NBN, BARD1, BRIP1, RAD50, RAD51C, RAD51D, MRE11, ATR, Fanconi anemia complementation group of genes (FANCA, FANCC, FANCD2, FANCE, FANCF, FANCG, FANCL). Other key eligibility criteria include metastatic disease treated with at least one prior line of chemotherapy, no deleterious BRCA1/2 mutation, and no prior platinum exposure. In cohort A, TNBC patients must have a HRD score of ≥ 42. Eligible patients will receive oral talazoparib (1.0 mg/day, 28-day cycles) until disease progression or unacceptable toxicity. Endpoints & Statistical Plan: The primary endpoint is objective response rate (ORR). Secondary endpoints include clinical benefit rate (CBR), progression free survival (PFS), and safety. In this study, we have set a null hypothesis of ≤ 5% objective response rate and alternative response rate of ≥ 20% based on RECIST 1.1. Interim analysis will be performed after accrual of 10 patients in each cohort. If at least one out of the 10 patients responds, then we will accrue 19 additional patients for a total of 29 patients in each cohort. At least four patients have to respond out of the 29 patients in each cohort to declare statistical significance at a one-sided 5% level with 80% power or better. This trial is enrolling patients at Stanford University in California (NCT 02401347). Citation Format: Afghahi A, Chang P-J, Ford JM, Telli ML. The Talazoparib Beyond BRCA (TBB) trial: A phase II clinical trial of talazoparib (BMN 673) in BRCA1 and BRCA2 wild-type patients with (i) advanced triple-negative breast cancer (TNBC) and homologous recombination deficiency (HRD) as assessed by myriad genetics HRD assay, and (ii) advanced HER2-negative breast cancer (BC) with either a germline or somatic mutation in homologous recombination (HR) pathway genes. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr OT2-05-04.

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

1549 Background: While germline pathogenic variants (PVs) in BRCA1/2 account for a large proportion of hereditary breast cancer (BC), PVs in PALB2, CHEK2 and ATM are increasingly detected. However, the phenotype and clinical features of invasive BC with these PVs have not been fully described. Methods: We identified patients with a PV or likely PV in PALB2, CHEK2 or ATM tested clinically at Stanford between 2014 - 2019 who provided informed consent to be included in a prospective cancer genetics registry. Data on baseline demographics, genetic testing history, and clinicopathologic features of diagnosed BC were collected. For patients with a subsequent diagnosis of metastatic BC, we calculated disease-free interval (DFI). Results: 130 patients met inclusion criteria for analysis: ATM (N=39), CHEK2 (N=58), PALB2 (N=33). Nearly all (98.5%) were women, with 2 male BC in ATM carriers. Non-Hispanic White ethnicity was most common in ATM (64.1%, 95% CI 48.4%-77.3%) and CHEK2 carriers (69.0%, 95% CI 56.1%-79.4%), but comprised only 39.4% (95% CI 24.7%-56.4%) in PALB2 carriers. Asian/Pacific Islander (24.2%, 95% CI 12.6%-41.3%) and Hispanic (30.3%, 95% CI 17.3%-47.5%) ethnicities were enriched among PALB2 mutation carriers. In total, 97.7% learned of their PV status only after a preceding diagnosis of BC and 43.1% were diagnosed with BC at age ≤ 45. Data regarding invasive BC subtypes, incidence of subsequent primary BC, and metastatic recurrence are listed below in the table. Additional data on stage, grade and sites of metastatic spread will be presented. Conclusions: We observed clinically important differences in the spectrum of BC subtypes among carriers of ATM, CHEK2 and PALB2 PVs, in addition to racial/ethnic differences with Asian/Pacific Islander and Hispanic ethnicity enriched among carriers of PALB2 PVs. [Table: see text]

Two PARP1 inhibitors, olaparib and talazoparib, garnered regulatory approvals for the treatment of advanced HER2-negative breast cancer associated with a germline BRCA1 or BRCA2 mutation in 2018. The approvals were based on a prolongation of progression-free survival with PARP inhibitor monotherapy compared to non-DNA damaging single agent chemotherapy in the 1st - 4th line metastatic setting. While the availability of these therapies has increased therapeutic options for this group of patients, median progression-free survival ranged from 7 - 8.6 months and no overall survival advantage has been observed to date. While response rates with PARP inhibitor monotherapy are high, development of resistance remains a significant clinical problem. Further, how PARP inhibitor monotherapy compares with platinum-based chemotherapy in this group of patients has been unclear. The recently reported phase III BROCADE 3 clinical trial examining carboplatin and paclitaxel with the addition of veliparib or placebo added important insights. This was the first phase III trial in patients with advanced germline BRCA1 and BRCA2 mutation-associated HER2-negative breast cancer that examined the use of a PARP inhibitor combined with DNA damaging chemotherapy in the 1st-3rd line setting followed by blinded monotherapy after discontinuation of chemotherapy. The median progression-free survival was significantly prolonged with the addition of veliparib (14.5 versus 12.6 months) with 26% of patients in the veliparib arm remaining progression-free at 36 months. Median overall survival was 33.5 months in the veliparib arm compared to 28.2 months in placebo with 44% of patients in the placebo arm crossing over to receive veliparib after disease progression. While important differences exist between these three trials, BROCADE 3 has reported the longest progression-free and overall survival to date with PARP inhibitor therapy in advanced germline BRCA1 and BRCA2 mutation-associated breast cancer. Beyond BRCA1 and BRCA2, PARP inhibitors are also being investigated in homologous recombination deficient advanced breast cancer in a number of clinical trials. In the Talazoparib Beyond BRCA study, high clinical activity was noted in germline PALB2 mutation carriers. The Olaparib Expanded trial is ongoing. Citation Format: ML Telli. Clinical indications of PARP1 inhibitors and other targets [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 ES12-1.

Purpose There are currently no targeted therapies approved for triple-negative breast cancer (TNBC). A tumor necrosis factor α ( TNFα)–based gene expression signature (GS) predictive of sensitivity to LCL161, inhibitor of apoptosis antagonist, was translated into a clinical assay and evaluated in a neoadjuvant trial. Patients and Methods Women with localized TNBC (T2/N0–2/M0) were prospectively stratified by GS status and randomly assigned (1:1) to receive oral LCL161 (1,800 mg once per week) and intravenous paclitaxel (80 mg/m2 once per week; combination arm) or paclitaxel alone (control arm) for 12 weeks, followed by surgery. The primary objective was to determine whether neoadjuvant LCL161 enhances efficacy of paclitaxel, defined by > 7.5% increase in the pathologic complete response (pCR, breast) rate, stratified by GS. Results Of 209 patients enrolled (207 with valid GS scores), 30.4% had GS-positive TNBC. In the GS-positive group, pCR was higher in the combination versus the control arm (38.2% v 17.2%), with 88.8% posterior probability of > 7.5% increase in pCR. However, in the GS-negative group, the pCR was lower in the combination group (5.6% v 16.4%), with 0% posterior probability of > 7.5% increase in pCR. A higher incidence of grade 3 or 4 adverse events in the combination arm included neutropenia (24.5%) and diarrhea (5.7%). Overall, 19 patients (18.1%) in the combination arm discontinued treatment because of adverse events, including pyrexia (n = 5), pneumonia (n = 4), and pneumonitis (n = 4), versus five patients (4.9%) in the control arm. Conclusion This neoadjuvant trial provides evidence supporting a biomarker-driven targeted therapy approach for selected patients with GS-positive TNBC and demonstrates the utility of a neoadjuvant trial for biomarker validation and drug development, but also highlights toxicity risk. Future neoadjuvant clinical trials should carefully weigh these considerations for targeted therapy development in biomarker-defined TNBC.

Triple-negative breast cancer (TNBC) is associated with worse outcomes relative to other breast cancer subtypes. Chemotherapy remains the standard-of-care systemic therapy for patients with localized or metastatic disease, with few biomarkers to guide benefit. We will discuss recent advances in our understanding of two key biological processes in TNBC, homologous recombination (HR) DNA repair deficiency and host anti-tumor immunity, and their intersection. Recent advances in our understanding of homologous recombination (HR) deficiency, including FDA approval of PARP inhibitor olaparib for BRCA1 or BRCA2 mutation carriers, and host anti-tumor immunity in TNBC offer potential for new and biomarker-driven approaches to treat TNBC. Assays interrogating HR DNA repair capacity may guide treatment with agents inducing or targeting DNA damage repair. Tumor infiltrating lymphocytes (TILs) are associated with improved prognosis in TNBC and recent efforts to characterize infiltrating immune cell subsets and activate host anti-tumor immunity offer promise, yet challenges remain particularly in tumors lacking pre-existing immune infiltrates. Advances in these fields provide potential biomarkers to stratify patients with TNBC and guide therapy: induction of DNA damage in HR-deficient tumors and activation of existing or recruitment of host anti-tumor immune cells. Importantly, these advances provide an opportunity to guide use of existing therapies and development of novel therapies for TNBC. Efforts to combine therapies that exploit HR deficiency to enhance the activity of immune-directed therapies offer promise. HR deficiency remains an important biomarker target and potentially effective adjunct to enhance immunogenicity of ‘immune cold’ TNBCs.

Purpose: Tumor-infiltrating lymphocytes (TIL) in pretreatment biopsies are associated with improved survival in triple-negative breast cancer (TNBC). We investigated whether higher peripheral lymphocyte counts are associated with lower breast cancer–specific mortality (BCM) and overall mortality (OM) in TNBC. Experimental Design: Data on treatments and diagnostic tests from electronic medical records of two health care systems were linked with demographic, clinical, pathologic, and mortality data from the California Cancer Registry. Multivariable regression models adjusted for age, race/ethnicity, socioeconomic status, cancer stage, grade, neoadjuvant/adjuvant chemotherapy use, radiotherapy use, and germline BRCA1/2 mutations were used to evaluate associations between absolute lymphocyte count (ALC), BCM, and OM. For a subgroup with TIL data available, we explored the relationship between TILs and peripheral lymphocyte counts. Results: A total of 1,463 stage I–III TNBC patients were diagnosed from 2000 to 2014; 1,113 (76%) received neoadjuvant/adjuvant chemotherapy within 1 year of diagnosis. Of 759 patients with available ALC data, 481 (63.4%) were ever lymphopenic (minimum ALC Conclusions: Higher peripheral lymphocyte counts predicted lower mortality from early-stage, potentially curable TNBC, suggesting that immune function may enhance the effectiveness of early TNBC treatment. Clin Cancer Res; 24(12); 2851–8. ©2018 AACR.