Translational Breast Cancer Research Consortium Research Articles

Neratinib and ado-trastuzumab emtansine for pretreated and untreated human epidermal growth factor receptor 2 (HER2)-positive breast cancer brain metastases: Translational Breast Cancer Research Consortium trial 022

Treatment options for human epidermal growth factor receptor 2 (HER2)-positive breast cancer brain metastases (BCBMs) remain limited. We previously reported central nervous system (CNS) activity for neratinib and neratinib-capecitabine. Preclinical data suggest that neratinib may overcome resistance to ado-trastuzumab emtansine (T-DM1) when given in combination. In Translational Breast Cancer Research Consortium (TBCRC) 022's cohort 4, we examined the efficacy of neratinib plus T-DM1 in patients with HER2-positive BCBM. In this multicenter, phase II study, patients with measurable HER2-positive BCBM received neratinib 160 mg daily plus T-DM1 3.6 mg/kg intravenously every 21 days in three parallel-enrolling cohorts [cohort 4A-previously untreated BCBM, cohorts 4B and 4C-BCBM progressing after local CNS-directed therapy without (4B) and with (4C) prior exposure to T-DM1]. Cycle 1 diarrheal prophylaxis was required. The primary endpoint was the Response Assessment in Neuro-Oncology-Brain Metastases (RANO-BM) by cohort. The overall survival (OS) and toxicity were also assessed. Between 2018 and 2021, 6, 17, and 21 patients enrolled in cohorts 4A, 4B, and 4C. Enrollment was stopped prematurely for slow accrual. The CNS objective response rate in cohorts 4A, 4B, and 4C was 33.3% [95% confidence interval (CI) 4.3% to 77.7%], 35.3% (95% CI 14.2% to 61.7%), and 28.6% (95% CI 11.3% to 52.2%), respectively; 38.1%-50% experienced stable disease for ≥6 months or response. Diarrhea was the most common grade 3 toxicity (22.7%). The median OS was 30.2 [cohort 4A; 95% CI 21.9-not reached (NR)], 23.3 (cohort 4B; 95% CI 17.6-NR), and 20.9 (cohort 4C; 95% CI 14.9-NR) months. We observed intracranial activity for neratinib plus T-DM1, including those with prior T-DM1 exposure, suggesting synergistic effects with neratinib. Our data provide additional evidence for neratinib-based combinations in patients with HER2-positive BCBM, even those who are heavily pretreated.

ETHAN: A phase II study comparing different endocrine therapies for male breast cancer.

TPS632 Background: Male breast cancer is a rare disease, and most cases are hormone receptor-positive (HR+). Due to a lack of clinical trials, male breast cancer has historically been treated based on data extrapolated from women. However, there are substantial knowledge gaps in the comparative efficacy, safety, and patient-reported outcomes of endocrine therapies for male breast cancer. While tamoxifen is the current standard of care, additional data are warranted for aromatase inhibitors (AI), gonadal suppression, and cyclin-dependent kinase 4/6 (CDK4/6) inhibitors. Methods: This is an open-label, multicenter, randomized, phase II trial designed to evaluate different endocrine therapies in men with HR+ and human epidermal growth factor receptor 2 (HER2)-negative breast cancer. A total of 60 men will be enrolled across nine (9) sites within the Translational Breast Cancer Research Consortium (TBCRC). Key eligibility criteria include male sex and stage I, II, or III HR+/HER2- breast cancer before surgical resection of the primary tumor and axillary nodes. Key exclusion criteria include prior anti-cancer therapy for the current breast cancer or any other malignancy within the past 12 months, and inflammatory breast cancer. The trial has two phases. The first phase is a window of opportunity component in which newly diagnosed men are randomized 1:1:1 to either tamoxifen (Arm A), anastrozole (Arm B), or anastrozole plus degarelix (Arm C) given for three weeks. The primary endpoint for the window phase is Ki-67 reduction from the baseline diagnostic biopsy to the research biopsy at the end of the window phase. The second phase consists of neoadjuvant treatment, in which the tamoxifen group is randomized 1:1 to tamoxifen (Arm D) versus tamoxifen plus abemaciclib (Arm E), and the anastrozole alone (Arm B) and anastrozole plus degarelix (Arm C) groups are merged and then randomized 1:1 to anastrozole plus degarelix (Arm F) versus anastrozole plus degarelix plus abemaciclib (Arm G). The duration of the neoadjuvant phase is four (4) months, and the primary endpoint of this phase is residual cancer burden (RCB) index at time of surgery. The trial is powered for the RCB endpoint in a 2 x 2 factorial design to detect a 0.6 unit decrease in RCB index with 80% power and alpha=10%. For the Ki-67 endpoint, we assume an approximately 50% reduction in Arms A and B; Arm C will be of interest if it leads to ≥80% reduction in Ki-67. Secondary endpoints include: estradiol and testosterone levels at baseline, end of window, and during neoadjuvant phase; preoperative endocrine prognostic index (PEPI) score at surgery; adverse events; and patient-reported outcomes (including quality of life). Tumor tissue will be collected for correlative analyses. The study opened to enrollment at Dana-Farber in October 2023, and additional sites will open in 2024. Clinical trial information: NCT05501704 .

Abstract PO2-20-01: The STOP-HER2 Trial: A Phase 2 Study of Stopping Trastuzumab - Outcomes in Patients with HER2+ Metastatic Breast Cancer (TBCRC 062)

Abstract BACKGROUND: Anti-HER2 therapies have transformed the trajectory for patients with HER2-positive (HER2+) MBC. A subset of patients with HER2+ MBC do exceptionally well and remain on maintenance anti-HER2 therapy for many years. However, current therapy is non-curative and patients are treated indefinitely. While these therapies often are well-tolerated, they may cause significant toxicities, are expensive, and typically require frequent infusion and provider visits. Case reports and retrospective series demonstrate that some patients may do well after stopping anti-HER2 treatment. We currently lack prospective data on the likelihood of clinical impact of successful treatment discontinuation, outcomes among patients who progress and restart HER2-directed therapy, and tools to predict who may safely stop therapy. In this study, we will enroll pts with an exceptional response to anti-HER2 therapy. Pts may elect to either continue or stop anti-HER2 therapy and will be followed clinically and radiographically on a protocol-specified schedule. Considering the central role of patients in choosing the study intervention arm, and the unique nature of stopping therapy as a treatment intervention, patient advocates have been deeply involved in the study design to ensure patient concerns are being heard and addressed. We will retrospectively assess minimal residual disease (MRD), measured in plasma, as a biomarker of ongoing response, in a step toward shifting the treatment paradigm for pts with HER2+ MBC. METHODS: STOP-HER2 is a prospective, non-randomized, phase II, multicenter study of either continuation (cohort 1) or cessation (cohort 2) of anti-HER2 therapy in exceptional responders with HER2+ MBC. Eligible patients must have biopsy-proven HER2+ MBC by ASCO/CAP guidelines and must have been receiving first-line anti-HER2 therapy for MBC for at least 3 years without evidence of progressive disease (PD) as determined by the treating investigator. Patients with prior brain-only PD or oligo-PD outside the brain are eligible at least 2 years after local treatment to the central nervous system (CNS) and in absence of subsequent PD. Up to fifty-two participants will be enrolled into cohort 2, and an additional thirty participants enrolled into the cohort 1, at 10 US sites within the Translational Breast Cancer Research Consortium. Co-primary endpoints are the 1-year progression-free survival (PFS) in cohorts 2 and 1, separately. Secondary endpoints include the clinical benefit rate upon re-initiation of anti-HER2 therapy for patients in cohort 2 experiencing PD after treatment discontinuation; and 3-year overall survival in both cohorts. Correlative endpoints include MRD status at baseline and the correlation between MRD dynamics and outcomes. Patient-reported outcomes will be collected and analyzed, including quality of life, illness intrusiveness, financial toxicity, anxiety, and decision regret. The study will use a two-stage design to assess the primary objective of estimating the rate of participants who are free of progression at one year after discontinuing anti-HER2 therapy. If 50% or less are free of progression at one year, stopping HER2 therapy would not be considered a viable treatment plan (null hypothesis). The study is designed to have 80% power to reject the null hypothesis at the 10% type I error rate when 68% of exceptional responders are free of progression at one year after stopping HER2 therapy. STOP-HER2 began enrollment in Q2 2023 (NCT05721248). Citation Format: Heather Parsons, Kathryn Ruddy, Stefania Morganti, Karen Smith, Victoria Attaya, Eliza Kallfelz, Michelle DeMeo, Jamie LaScala, Shirley Mertz, Teri Pollastro, Patricia Spears, Adam Brufsky, Chau Dang, Susan Dent, Ahmed Elkhanany, WIlliam Gwin, Ciara O'Sullivan, Kathy Miller, Sara Nunnery, Elaine Walsh, Anna Maria Storniolo, Sara Tolaney, Nabihah Tayob, Antonio Wolff, Eric Winer, Mothaffar Rimawi, Ian Krop, Nancy Lin. The STOP-HER2 Trial: A Phase 2 Study of Stopping Trastuzumab - Outcomes in Patients with HER2+ Metastatic Breast Cancer (TBCRC 062) [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO2-20-01.

Abstract PS03-07: Morphometric signature identifies ductal carcinoma in situ of the breast with low risk of progression to invasive breast cancer

Abstract Background. Ductal carcinoma in situ (DCIS) is a frequently found precursor of invasive breast cancer (IBC). However, the majority of DCIS will never progress to IBC. As we cannot distinguish yet which DCIS will remain indolent (‘harmless’) from those that might progress in the future to IBC, almost all women with DCIS are intensively treated by surgery, often followed by radiotherapy. This brings an urgent clinical need to learn distinguishing harmless from potentially progressive DCIS to save many women with indolent DCIS the burden of unnecessary overtreatment. Aim. We aimed to investigate if the geometry and spatial configuration of DCIS ducts in Hematoxylin-Eosin (H&E) stained tissue sections are related to the risk of progression of DCIS to ipsilateral IBC (iIBC). Methods. We obtained data from a population-based cohort of women diagnosed with primary DCIS between 1989 and 2004 in the Netherlands, treated with breast conserving surgery (BCS) only and a median follow-up time of 12 years. A nested case-control study (n=689) was designed in which patients diagnosed with iIBC recurrences during follow-up were considered as “cases” (n= 226) and those with no subsequent iIBC as “controls” (n=463). The DCIS and stroma regions were digitally annotated on H&E-stained whole slide images (WSIs) by a pathologist as ground truth for the deep learning neural network of HALO AI module (IndicaLabs). We developed a computational pipeline to automatically detect and measure stroma areas, DCIS ducts, and the nucleus of their cells. We validated the accuracy of DCIS detection in H&Es WSIs from an external study, in which DCIS regions were digitally annotated by an independent pathologist (Translational Breast Cancer Research Consortium, TBCRC). We classified cases and controls according to morphological measurements using logistic ridge regression with double-loop cross-validation, followed by hierarchical clustering. The risk of subsequent iIBC after primary DCIS diagnosis was evaluated by multivariate Cox proportional hazards models. Results. The accuracy of DCIS detection performed by the computational pipeline was compared with pathologist annotations in 20 slides from the TBCRC study. Results showed a satisfactory DCIS overlap area agreement of 0.76 (0.68 – 0.83). We applied the DCIS computational pipeline on the case-control series. We obtained 15 morphological measurements for each DCIS duct, such as duct area, cell density, distance between ducts, average nucleus area, etc. We calculated 8 distribution parameters from each measurement in each WSI, including median and range. After leaving out redundant variables, 55 unique morphometric variables were obtained, representing the heterogeneity of DCIS ducts per WSI. The c lassifier revealed a median area-under the curve (AUC) of 0.66 (0.55-0.77) to predict 5-years free of iIBC, 0.59 (0.50-0.67) to predict 10-years and 0.60 (0.52-0.68) to predict 15-years. The 30 variables with the highest association with outcome were used to build four morphometric signatures. Signature number 1, which is characterized by lesions with small-sized ducts, a lower number of cells and a lower DCIS/stroma area ratio, showed a significant lower risk of developing iIBC compared to the other three signatures in a multivariate Cox regression model including grade, ER, COX-2 and HER2 expression: HR = 0.56 (0.28-0.78 95%CI). Conclusion. We developed a computational pipeline able to detect and measure DCIS ducts in H&E WSIs with high accuracy and reproducibility. DCIS lesions presenting the morphometric signature of small-sized DCIS ducts have a very low chance to progress to invasive breast cancer. After successful validation, our morphometric method will serve as a robust and easy to implement biomarker for de-escalation strategies in DCIS, and as such, could limit unnecessary overtreatment in the near future. Citation Format: Marcelo Sobral-Leite, Simon Castillo, Shiva Vonk, Xenia Melillo, Noomie Lam, Brandi de Bruijn, Yeman Hagos, Joyce Sanders, Mathilde Almekinders, Lindy Visser, Emilie Groen, Carolien Van der Borden, Petra Kristel, Ercan Caner, Leyla Azarang, Yinyin Yuan, Renee Menezes, Esther Lips, Jelle Wesseling, Grand Challenge PRECISION Consortium. Morphometric signature identifies ductal carcinoma in situ of the breast with low risk of progression to invasive breast cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PS03-07.

Abstract PO5-26-11: The Breast Cancer Research Foundation Drug Research Collaborative – A unique and innovative model for industry-funded, academically driven research to advance the field of breast cancer

Abstract The Breast Cancer Research Foundation (BCRF) is committed to preventing and curing breast cancer through groundbreaking research. In pursuit of this mission, the BCRF launched the Drug Research Collaborative (DRC) in 2016—a pioneering program designed to bridge the gap between academic investigators and access to investigational therapies, thereby fostering greater academic-driven research in breast cancer. The DRC's primary objective is to fund independent, innovative, and high-quality investigator-initiated trials (IITs) and pre-clinical/translational research projects. In conventional drug development, industry-sponsored registration trials play a crucial role, leaving limited resources and scope for exploratory and translational IITs that fall outside the industry's drug approval strategy. Additionally, industry-funded IIT research faces challenges such as reputational risks, perceived influence during internal review processes, intellectual property (IP) concerns, and logistics/program management burdens. The BCRF-DRC program addresses these challenges by issuing requests for proposals to generate creative and unbiased ideas, which are then vetted through an academic review process involving leading breast cancer experts. The most promising research projects are selected for further advancement. The BCRF-DRC program is facilitated by the BCRF research staff, providing project management, while the Translational Breast Cancer Research Consortium (TBCRC), founded by the BCRF and also supported by Susan G. Komen, supports the clinical trial aspects of the program. Since its inception, the BCRF-DRC has expanded from one to three industry partners, securing a total funding of $25 million for 15 projects, including seven clinical trials and eight pre-clinical projects. This abstract reports on the ongoing progress and outcomes achieved by these three programs. The BCRF-DRC represents a revolutionary paradigm in research funding and collaboration by harnessing the collective power of industry partners, philanthropic organizations, and academic institutions. Through this collaborative effort, the BCRF-DRC provides a unique platform for researchers to accelerate the translation of scientific discoveries into effective clinical interventions, thus making significant strides in the field of breast cancer in the coming decades. By empowering academic investigators, fostering unbiased research, and addressing the limitations of industry-funded IITs, the BCRF-DRC is revolutionizing breast cancer research and driving the development of novel interventions. This abstract highlights the transformative potential of the BCRF-DRC program and its contribution to advancing breast cancer treatments and ultimately improving patient outcomes. The success of this collaborative model serves as a testament to the power of multi-sector partnerships and the pivotal role they play in shaping the future of breast cancer research. Citation Format: Unnati Jariwala, Dorraya El-Ashry, Judy Garber, Larry Norton. The Breast Cancer Research Foundation Drug Research Collaborative – A unique and innovative model for industry-funded, academically driven research to advance the field of breast cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO5-26-11.

Evaluation of Alisertib Alone or Combined With Fulvestrant in Patients With Endocrine-Resistant Advanced Breast Cancer

Aurora A kinase (AURKA) activation, related in part to AURKA amplification and variants, is associated with downregulation of estrogen receptor (ER) α expression, endocrine resistance, and implicated in cyclin-dependent kinase 4/6 inhibitor (CDK 4/6i) resistance. Alisertib, a selective AURKA inhibitor, upregulates ERα and restores endocrine sensitivity in preclinical metastatic breast cancer (MBC) models. The safety and preliminary efficacy of alisertib was demonstrated in early-phase trials; however, its activity in CDK 4/6i-resistant MBC is unknown. To assess the effect of adding fulvestrant to alisertib on objective tumor response rates (ORRs) in endocrine-resistant MBC. This phase 2 randomized clinical trial was conducted through the Translational Breast Cancer Research Consortium, which enrolled participants from July 2017 to November 2019. Postmenopausal women with endocrine-resistant, ERBB2 (formerly HER2)-negative MBC who were previously treated with fulvestrant were eligible. Stratification factors included prior treatment with CDK 4/6i, baseline metastatic tumor ERα level measurement (<10%, ≥10%), and primary or secondary endocrine resistance. Among 114 preregistered patients, 96 (84.2%) registered and 91 (79.8%) were evaluable for the primary end point. Data analysis began after January 10, 2022. Alisertib, 50 mg, oral, daily on days 1 to 3, 8 to 10, and 15 to 17 of a 28-day cycle (arm 1) or alisertib same dose/schedule with standard-dose fulvestrant (arm 2). Improvement in ORR in arm 2 of at least 20% greater than arm 1 when the expected ORR for arm 1 was 20%. All 91 evaluable patients (mean [SD] age, 58.5 [11.3] years; 1 American Indian/Alaskan Native [1.1%], 2 Asian [2.2%], 6 Black/African American [6.6%], 5 Hispanic [5.5%], and 79 [86.8%] White individuals; arm 1, 46 [50.5%]; arm 2, 45 [49.5%]) had received prior treatment with CDK 4/6i. The ORR was 19.6%; (90% CI, 10.6%-31.7%) for arm 1 and 20.0% (90% CI, 10.9%-32.3%) for arm 2. In arm 1, the 24-week clinical benefit rate and median progression-free survival time were 41.3% (90% CI, 29.0%-54.5%) and 5.6 months (95% CI, 3.9-10.0), respectively, and in arm 2 they were 28.9% (90% CI, 18.0%-42.0%) and 5.4 months (95% CI, 3.9-7.8), respectively. The most common grade 3 or higher adverse events attributed to alisertib were neutropenia (41.8%) and anemia (13.2%). Reasons for discontinuing treatment were disease progression (arm 1, 38 [82.6%]; arm 2, 31 [68.9%]) and toxic effects or refusal (arm 1, 5 [10.9%]; arm 2, 12 [26.7%]). This randomized clinical trial found that adding fulvestrant to treatment with alisertib did not increase ORR or PFS; however, promising clinical activity was observed with alisertib monotherapy among patients with endocrine-resistant and CDK 4/6i-resistant MBC. The overall safety profile was tolerable. ClinicalTrials.gov Identifier: NCT02860000.

Abstract P6-08-07: Reasons for Reduced Willingness to Participate in Clinical Trials During the COVID-19 Pandemic: The Translational Breast Cancer Research Consortium (TBCRC) 057 Survey

Abstract Background: Historically, less than 10% of adult patients with cancer enroll in clinical trials, however, enrollment dropped further at the onset of the COVID-19 pandemic. Barriers to trial participation during the pandemic have not been reported. As part of the TBCRC 057 survey on the impact of the pandemic on willingness to participate in breast cancer trials, we assessed reasons for reluctance to participate in trials during the pandemic. Methods: US residents who self-reported a breast cancer diagnosis were eligible to complete the online survey 8/6/21-9/30/21. Respondents indicated whether they were current trial participants and, if not, their willingness to consider participating in a trial during the pandemic using a 5-point scale (0-not at all willing to 4-definitely willing). Respondents who were not current trial participants and who were not “definitely willing” to consider participation during the pandemic were characterized as “reluctant” and asked to select reasons for their reluctance from a checklist. Pandemic-related anxiety was assessed on an 11-point scale (0-no anxiety to 10-worst anxiety possible). Respondents indicated how the option to conduct trial activities online would affect their decision to participate in a trial (much less likely, somewhat less likely, would not affect my decision, somewhat more likely, or much more likely). In exploratory analyses, we evaluated whether pandemic-related anxiety and favorable reactions towards opportunities to conduct trial activities online were associated with reluctance to consider trial participation during the pandemic due to fear of SARS-CoV-2 exposure. Means were compared with two sample t-tests and proportions with Fisher’s exact tests. Results: Of 385 survey respondents, 185 (48%) were characterized as reluctant to consider trial participation during the pandemic. Among these 185, median age was 55 (range 25-80), 85.7% were non-Hispanic White, 48.1% had metastatic disease and 44.2% received care at academic centers. Reasons for reluctance to consider trial participation during the pandemic cited by ≥15% of the 185 reluctant respondents are shown in the Table. Respondents who selected fear of exposure to SARS-CoV-2 as a reason for their reluctance to consider participating in a trial during the pandemic had higher mean pandemic-related anxiety (7.0 vs 5.2, p&amp;lt; 0.001). These respondents were more likely to indicate telemedicine doctor visits (p=0.01), virtual consents (p=0.001) and online study questionnaires (p=0.001) would make them somewhat or much more likely to participate in trials than respondents who did not select fear of exposure to SARS-CoV-2 as a reason for their reluctance. Conclusions: Reasons for reluctance of patients with breast cancer to consider participation in clinical trials during the pandemic are multifactorial. Although concerns about safety and efficacy remain prominent, fear of exposure to SARS-CoV-2 drives unwillingness to participate in &amp;gt;25% of reluctant patients. Trial accrual may benefit from incorporation of electronic activities when possible. Table Citation Format: Karen L. Smith, Carolyn Mead-Harvey, Gina L. Mazza, Albert E. Holler, Eileen Shinn, Elizabeth Frank, Michelle Melisko, Cyd Eaton, Jeannine M. Salamone, Teri Pollastro, Patricia Spears, Antonio C. Wolff, Gabrielle B. Rocque. Reasons for Reduced Willingness to Participate in Clinical Trials During the COVID-19 Pandemic: The Translational Breast Cancer Research Consortium (TBCRC) 057 Survey [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P6-08-07.

Abstract PD7-03: Translational Breast Cancer Research Consortium Trial 022: Neratinib and Trastuzumab-Emtansine for HER2+ Breast Cancer Brain Metastases (BCBM)

Abstract PURPOSE: Treatment options for patients (pts) with HER2+ BCBM remain limited. We previously reported that neratinib monotherapy is associated with a volumetric central nervous system objective response rate (CNS ORR) of 8%, whereas the combination of neratinib and capecitabine resulted in a volumetric CNS ORR of 49% (in lapatinib-naïve pts). Preclinical data suggest that neratinib may overcome resistance to trastuzumab-emtansine (T-DM1) and that the combination has potential CNS efficacy. Here, we report results of neratinib plus T-DM1 in pts with HER2+ BCBM. PATIENTS AND METHODS: In this prospective, multicenter, phase II study, pts with measurable HER2+ BCBM received neratinib 160 mg orally once daily plus T-DM1 3.6 mg/kg IV every 21 days in three parallel-enrolling cohorts. Cohort 4A enrolled pts with previously untreated brain metastases. Cohort 4B enrolled pts with BCBM progressing after prior local CNS-directed therapy without prior exposure to T-DM1. Cohort 4C enrolled pts with BCBM progressing after prior local CNS-directed therapy who had previous exposure to T-DM1. Diarrhea prophylaxis with colestipol and loperamide was required during cycle 1. Cohorts 4A and 4B were single-stage with a planned enrollment of 20 patients; cohort 4C had a two-stage design, with a requirement for at least 1 of the first 9 pts to achieve a response in order to enroll a total of 24 patients. The primary endpoint was Response Assessment in Neuro-Oncology-Brain Metastases (RANO BM) in each cohort separately. Correlative studies included patient-reported outcomes (PROs) for gastrointestinal toxicity. RESULTS: We enrolled 6, 17, and 21 patients to cohorts 4A, 4B, and 4C, during 11/07/2018 – 11/01/2021. Enrollment was stopped prematurely due to slow accrual. Across Cohorts 4A-4C, the median number of prior lines of chemotherapy prior to enrollment was 2 (range 1-10); 25% received prior lapatinib and no patients received prior tucatinib. In cohorts 4B and 4C (prior CNS-treated cohorts), 33% had prior CNS surgery and &amp;gt;94% had prior CNS radiation. Among evaluable patients, CNS ORR in cohorts 4A (n=6), 4B (n=16), and 4C (n=21) was 50.0% (95% CI 18.8- 81.2%), 25.0% (95% CI 8.3-52.6%), and 38.1% (95% CI 19.0-61.3%), respectively. Median (range) number of cycles completed for 4A, 4B, and 4C was 4.5 (1-15), 4 (range 0-49+), and 6 (0-23); three patients on Cohort 4B remain on protocol therapy (cycles 14, 45, and 49). The overall survival at 12-months for cohorts 4A, 4B, and 4C was 83.3% (95% CI, 58.3-100%), 86.2% (95% CI 70-100%), and 83.3% (95% CI 67.6-100%). Diarrhea was the most common grade 3 toxicity (19.0–33.3% across cohorts); one grade 4 liver function event occurred in cohort 4B. Updated efficacy results will be reported at the meeting; PRO analyses are ongoing. CONCLUSION: Intracranial activity was observed for the combination of neratinib plus T-DM1 across all three enrolled cohorts, including those with prior T-DM1 exposure, suggesting synergistic effects of this treatment combination. Our data provide additional evidence for consideration of neratinib-based combinations in pts with HER2+ BCBM. Citation Format: Rachel Freedman, Siyang Ren, Nabihah Tayob, Rebecca Gelman, Karen L. Smith, Raechel Davis, Alyssa Pereslete, Victoria Attaya, Christine Cotter, Wendy Y. Chen, Cesar Augusto Santa-Maria, Catherine Van Poznak, Beverly Moy, Adam M. Brufsky, Michelle Melisko, Ciara C. O’Sullivan, Nadia Ashai, Yasmeen Rauf, Julie Nangia, Dario Trapani, Jennifer Savoie, Robyn Burns, Antonio C. Wolff, Eric Winer, Mothaffar Rimawi, Ian Krop, Nancy U. Lin. Translational Breast Cancer Research Consortium Trial 022: Neratinib and Trastuzumab-Emtansine for HER2+ Breast Cancer Brain Metastases (BCBM) [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr PD7-03.

Abstract P1-07-02: Using clinical characteristics and molecular markers to predict the risk of subsequent ipsilateral breast events after excision of DCIS

Abstract PURPOSE To examine incremental values of estrogen receptor (ER) status, body mass index (BMI), menopausal status, and a previously reported multi-gene classifier over commonly used clinical factors (i.e. age, tumor grade, comedonecrosis, surgical margins, and treatment) in predicting risk of any ipsilateral recurrence (IR) event within five years after DCIS diagnosis. METHODS A derivation cohort consisted of participants in the Translational Breast Cancer Research Consortium (TBCRC) 038, a retrospective multicenter cohort study in women undergoing surgical resection for DCIS between 01/01/1998 and 02/29/2016 (n=216). The validation cohort, the Repository of Archival Human Breast Tissue (RAHBT) at Washington University School of Medicine, provided cases meeting the same eligibility criteria as TBCRC038 (n=97). Participants in both cohorts had RNA-seq data and either developed IR 1-5y after initial DCIS diagnosis or were free from subsequent breast events for at least five years. The previously reported 812-gene classifier had been developed from a subset of the TBCRC038 samples using a negative-binomial regression model to identify differentially expressed genes in the primary tumor associated with subsequent recurrence events. This classifier has been shown to be highly correlated with 5-year invasive, DCIS, and all breast cancer events, and validated in the RAHBT cohort. Cox proportional hazards regression was used to estimate hazard ratios (HRs) of IR in the TBCRC038 cohort (76 with IR). The clinical score was developed using clinical predictors (aforementioned clinical factors and ER) and their regression coefficients from the model with the maximum predictive accuracy (e.g. c-index) and the minimum number of predictors; the summary score integrated the clinical score and multi-gene classifier. Predictive performance of both clinical and summary scores was validated in the RAHBT cohort (20 with IR). RESULTS In the TBCRC cohort derivation set, we used a multivariable model based on clinical factors alone (clinical score) and found that ER status, but not BMI or menopausal status, was independently associated with a higher IR risk (HR=2.06, 95% CI 1.18-3.58). Adding the multi-gene classifier to the clinical factors-based model (summary score) in the TBCRC038 test set increased predictive accuracy (c-index 0.68 to 0.70), with the genomic classifier-adjusted HR of 14.96 (95% CI 8.64-25.91). The summary score had higher predictive performance for IR risk than clinical score alone (c-index 0.82 vs. 0.70). In the RAHBT validation samples, model performance was similarly improved using summary scores clinical factors-based model plus multigene classifier as compared to clinical scores along (c-index 0.74 vs. 0.58). CONCLUSION Combining clinical factors and a multigene classifier provided more accurate risk estimates of IR within five years after excision of DCIS than clinical factors alone. Figure 1. Observed and predicted recurrence-free survival in the first five years after initial DCIS diagnosis in the RAHBT validation cohort, by risk groups defined by clinical scores (left) and clinical score plus multigene classifier (right). Citation Format: Ying Liu, Siri H. Strand, Lorraine King, Bryan Harmon, Fergus J. Couch, Kristalyn Gallagher, Mark Kilgore, Shi Wei, Angela DeMichele, Tari King, Priscilla F. McAuliffe, Jeffrey Marks, Carlo Maley, Robert West, E Shelley Hwang, Graham A. Colditz. Using clinical characteristics and molecular markers to predict the risk of subsequent ipsilateral breast events after excision of DCIS [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P1-07-02.

Molecular classification and biomarkers of clinical outcome in breast ductal carcinoma in situ: Analysis of TBCRC 038 and RAHBT cohorts.

Ductal carcinoma in situ (DCIS) is the most common precursor of invasive breast cancer (IBC), with variable propensity for progression. We perform multiscale, integrated molecular profiling of DCIS with clinical outcomes by analyzing 774 DCIS samples from 542 patients with 7.3 years median follow-up from the Translational Breast Cancer Research Consortium 038 study and the Resource of Archival Breast Tissue cohorts. We identify 812 genes associated with ipsilateral recurrence within 5 years from treatment and develop a classifier that predicts DCIS or IBC recurrence in both cohorts. Pathways associated with recurrence include proliferation, immune response, and metabolism. Distinct stromal expression patterns and immune cell compositions are identified. Our multiscale approach employed in situ methods to generate a spatially resolved atlas of breast precancers, where complementary modalities can be directly compared and correlated with conventional pathology findings, disease states, and clinical outcome.

Abstract OT1-18-08: Randomized phase II trial of pembrolizumab/carboplatin vs. carboplatin alone for breast cancer with chest wall recurrence: TBCRC044

Abstract Background: A significant number of patients with breast cancer may develop chest wall recurrence, which can be difficult to treat, and is associated with a poor prognosis. Given the inflammatory nature of chest wall disease, and the association of chest wall disease with lymphovascular invasion, we hypothesized that immunotherapy may be beneficial in this setting. Furthermore, combining immunotherapy and chemotherapy may have a synergistic effect; indeed, the combination of the anti-programmed cell death 1 (PD-1) antibody, pembrolizumab, with chemotherapy has been approved for metastatic triple negative breast cancer (TNBC). Consequently, in this study, we are evaluating the combination of pembrolizumab/carboplatin vs. carboplatin alone for chest wall recurrence. Trial design: This is a phase II study of patients with chest wall disease from breast cancer. Patients are randomized in a 2:1 manner to pembrolizumab/carboplatin x 6 cycles (Arm A) with the option to continue pembrolizumab +/- carboplatin after 6 cycles (Arm Ax) vs. carboplatin alone (Arm B) with the option to cross-over to pembrolizumab +/- carboplatin on progression (Arm Bx). Carboplatin is dosed at AUC 5 IV every 3 weeks, and pembrolizumab at 200 mg IV every 3 weeks. Trastuzumab may be continued with study treatment in patients with HER2 positive disease. Imaging scans (CT chest, abdomen, and pelvis, and bone scan) occur at baseline and every 3 cycles. Chest wall biopsies and peripheral blood is collected at baseline and after completing 2 cycles of treatment for correlative studies. Eligibility criteria: Patients must have chest wall disease from breast cancer. Distant metastases are allowed. TNBC, hormone receptor positive/HER2 negative disease (after 2 prior hormone therapies), and HER2 positive disease (progressed on standard HER2 directed treatment) are eligible. Any number of prior lines of chemotherapy are acceptable, including a prior platinum chemotherapy in the absence of disease progression on the platinum. Specific Aims: Primary aim is to determine disease control rate in the chest wall and other distant sites at 18 weeks of treatment with RECIST 1.1. Secondary aims including determining toxicity, progression-free survival, response based on irRECIST, and response based on tumor PD-L1 expression. Exploratory aims include studying changes in: 1) immune composition of tumor and peripheral blood, 2) peripheral blood cell-free DNA and circulating tumor cells, 3) soluble PD-L1 expression, and 4) association of MYC with PD-1 and immune markers, based on preclinical data demonstrating that MYC upregulates these markers. Statistical Methods: 84 patients (Arm A: 56, Arm B: 28) are being enrolled at 7 sites in the Translational Breast Cancer Research Consortium. The study is powered to identify a 20% difference in disease control rates between Arms A and B (HR 0.52, α= 0.10, ß=0.20). A futility analysis will occur for Arm B after 18 patients are enrolled to allow for early closure if lack of efficacy. Accrual: Present accrual is 57 patients (Arm A: 39, Arm B: 18). (NCT03095352). This trial is partly funded by grants from Merck and University of California San Francisco. Contact information: Neelima Vidula, MD, Massachusetts General Hospital, nvidula@mgh.harvard.edu Citation Format: Neelima Vidula, Rita Nanda, Kathy Miller, Leisha Emens, Vandana Abramson, Ben Park, Minetta C. Liu, Andrei Goga, Hope Rugo. Randomized phase II trial of pembrolizumab/carboplatin vs. carboplatin alone for breast cancer with chest wall recurrence: TBCRC044 [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr OT1-18-08.

Local Therapy Outcomes and Toxicity From the ATEMPT Trial (TBCRC 033): A Phase II Randomized Trial of Adjuvant Trastuzumab Emtansine Versus Paclitaxel in Combination With Trastuzumab in Women With Stage I HER2-Positive Breast Cancer

Human epidermal growth factor receptor 2 (HER2)-directed therapy improves local control among women with HER2-positive breast cancer. This retrospective analysis evaluates the safety and efficacy of radiation therapy (RT) among patients receiving adjuvant trastuzumab emtansine (T-DM1) or paclitaxel (T) plus trastuzumab (H) in the ATEMPT (Adjuvant Trastuzumab Emtansine Versus Paclitaxel in Combination With Trastuzumab) trial; Translational Breast Cancer Research Consortium (TBCRC) 033. Patients with stage I HER2-positive breast cancer were randomized 3:1 to receive adjuvant T-DM1 or TH after mastectomy or breast-conserving surgery (BCS). Breast RT was required after BCS and permitted after mastectomy. Patients receiving T-DM1 began RT after 12 weeks of therapy and received RT concurrently with T-DM1. Patients receiving TH began RT after paclitaxel, but concurrent with trastuzumab. RT records were retrospectively reviewed to determine details of radiation delivery and acute RT-related toxicity. Protocol therapy was initiated by 497 patients. Among the 299 BCS patients, 289 received whole breast RT (WBRT) and 10 partial breast. Among WBRT patients, 40.2% in the T-DM1 arm and 41.5% of TH patients received hypofractionated (≥2.5 Gy/fraction) RT. Eight mastectomy patients received RT, all conventional fractionation. Skin toxicity (grade ≥2) was seen in 33.9% of patients in the T-DM1 arm and 23.2% in the TH arm (P = .11). In conventionally fractionated WBRT patients, 44.7% had a grade ≥2 skin toxicity compared with 17.9% of patients receiving hypofractionation (P < .001). Five patients experienced pneumonitis after RT (T-DM1: n = 4, 1.0%; TH: n = 1, 0.9%). Three-year invasive disease-free survival was 97.8% for T-DM1 (95% confidence interval, 96.3-99.3) and 93.4% for TH (95% confidence interval, 88.7-98.2). Among the 18 invasive disease-free survival events, 7 were isolated locoregional recurrences (2, T-DM1; 5, TH). RT was well-tolerated when given concurrently with either T-DM1 or TH. Among BCS patients, hypofractionation resulted in lower grade ≥2 acute skin toxicity even with concurrent anti-HER2 therapy. Although follow-up was short, local recurrences were uncommon, attesting to the efficacy of HER2-directed therapy combined with RT.

Multi-center randomized study of pembrolizumab/carboplatin versus carboplatin alone in patients with chest wall disease from breast cancer: TBCRC 044.

TPS1111 Background: Chest wall recurrence is a subtype of breast cancer that is challenging to treat, and associated with a short duration of response to treatment and an increased risk of development of distant metastases. Given the inflammatory nature of this disease and the association of chest wall disease with lymphovascular invasion, which is correlated with higher programmed cell death 1 (PD-1) expression, we hypothesized that immunotherapy may be beneficial as treatment. Combinations of immunotherapy and chemotherapy have a synergistic effect and demonstrated efficacy in the treatment of metastatic triple negative breast cancer (TNBC). This study is evaluating the efficacy of pembrolizumab, an anti-PD-1 antibody, in combination with carboplatin, in patients with chest wall infiltration from breast cancer. This drug combination has shown efficacy in advanced lung cancer. Methods: This is a multicenter, 2:1 randomized phase II study of pembrolizumab/carboplatin (Arm A, 56 patients) vs. carboplatin (Arm B, 28 patients) in 84 patients with chest wall disease from breast cancer, with or without distant metastases. Patients may have TNBC, hormone receptor positive/HER2 negative (following receipt of 2 prior hormone therapies), or HER2 positive breast cancer (with option to continue trastuzumab on study). Pembrolizumab is administered as 200 mg IV every 3 weeks, and carboplatin as AUC 5 IV every 3 weeks. Patients on Arm A may continue pembrolizumab +/- carboplatin (Arm Ax) after completion of 6 cycles of treatment, while patients in Arm B can cross-over to pembrolizumab (+/- carboplatin) on progression (Arm Bx). Patients must have adequate organ function, performance status ≤ 2, and may have received any number of lines of prior chemotherapy. Patients undergo serial chest wall photography and imaging (CT chest, abdomen, and pelvis, and bone scan) at baseline and every 6 weeks, as well as blood collection for correlative studies and chest wall biopsies at baseline and after 2 cycles of treatment. The primary endpoint is disease control rate (RECIST 1.1) at 18 weeks of treatment, and the study is powered to determine a 20% difference in disease control rates between arms (HR 0.52, a = 0.10, ß = 0.20). An interim analysis will occur for Arm B after 18 patients are enrolled, with a stopping rule for futility. Secondary endpoints include progression-free survival, toxicity (NCI CTCAE), and response based on irRECIST and tumor programmed death ligand 1 (PD-L1) expression. Exploratory objectives include evaluating changes in soluble PD-L1, tumor and peripheral blood immune composition, circulating tumor cells and cell-free DNA, and MYC oncogene expression. This study (NCT03095352) is open at 7 sites in the Translational Breast Cancer Research Consortium (TBCRC). 52 patients are enrolled. Grant funding is provided by Merck and UCSF. Clinical trial information: NCT03095352 .

Trial in progress: A phase 1b/2 study of the PARP inhibitor niraparib in combination with trastuzumab in patients with metastatic HER2+ breast cancer (TBCRC 050).

TPS1098 Background: Approximately 20% of breast cancers (BC) express the human epidermal growth factor receptor 2 (HER2). Although HER2-directed therapies result in improved patient outcome, resistance ultimately occurs. Poly (ADP-Ribose) polymerase (PARP) inhibitors are currently indicated in cancers that express germline mutations in the DNA repair proteins BRCA1/2 due to their synthetic lethality against the homologous recombination repair (HR) pathway. In addition to its role in DNA damage repair, PARP1 has also been implicated in other cellular functions, including co-activation of genes such as NF-κB, which regulate tumor proliferation and HER2 drug resistance. Our group identified that HER2+ BC overexpress the PARP1 and phospho-p65 protein. In HER2+ BC cells and animal models, PARP inhibitors initiated apoptosis independent of a DNA repair deficiency, via inhibition of NF-kB signaling. Key proteins (p65, IKK-α) of the NF-κB-mediated growth pathways were reduced and IκBα was increased in the presence of PARPi, implicating another oncologic pathway in which HER2+ BC cells may be dependent. Methods: The study is a phase 1b/2, multicenter, single arm clinical trial evaluating the safety and efficacy of niraparib 200 mg orally days 1-21 with trastuzumab 6 mg/kg (cycle 1 loading dose of 8 mg/kg) intravenously on day 1 of a 21-day cycle for patients with unresectable or metastatic HER2+ BC. Eligible patients include metastatic HER2+ BC, progression on at least 1 prior HER2-targeted therapy, measurable disease, ECOG PS 0-1, and LVEF ≥ 50%. Stable/treated CNS disease allowed. Prior PARPi and known germline BRCA 1/2 excluded. Forty patients will be enrolled at 7 US sites within the Translational Breast Cancer Research Consortium. The primary objectives are determining the dose-limiting toxicity (DLT) of the combination and assessing the objective response rate. The phase 1b cohort has been completed (N=6). Enrollment in phase 2 began February 2021 with a total accrual goal of 40. Gehan’s two-stage design will be used assuming the response rate is at least 24% and the response rate will be estimated with Clopper-Pearson exact method. Correlative aims include assessing blood and tissue biomarkers (e.g. PARP1, p65, phosphor-p65, let-7a miRNA, NF-kB, ctDNA, etc.) for association with clinical benefit and to predict response to therapy. Clinical trial information: NCT03368729 .

Abstract OT-13-09: Translational breast cancer research consortium 044 trial: Randomized phase 2 study of pembrolizumab and carboplatin versus carboplatin alone for chest wall recurrence of breast cancer

Abstract Background: Chest wall recurrence may occur in up to 30% of patients with breast cancer, and is associated with a high morbidity and mortality. We hypothesized that immunotherapy may be beneficial in this setting because of the inflammatory nature of this disease, and the association of chest wall disease with lymphovascular invasion. Combination immunotherapy and chemotherapy may have a synergistic effect. In this study, we combined pembrolizumab, an anti-programmed cell death 1 (PD-1) antibody with carboplatin, in patients with chest wall disease. This combination has previously been shown to be effective in advanced lung cancer. Trial design: This is a 2:1 randomized phase II study of pembrolizumab and carboplatin (Arm A) versus carboplatin alone (Arm B) in patients with chest wall involvement from breast cancer. Pembrolizumab is dosed at 200 mg IV every 3 weeks, and carboplatin is dosed at AUC 5 IV every 3 weeks. Patients on Arm A have the option to continue on pembrolizumab alone after 6 cycles of combination treatment (Arm Ax). Patients on Arm B have the option to cross-over to pembrolizumab (+/- carboplatin) after 6 cycles of carboplatin alone (Arm Bx). Patients with HER2 positive disease may continue trastuzumab in addition to the study treatment. Patients undergo chest wall biopsies and peripheral blood collection for correlative studies at enrollment and after 2 cycles of treatment, and also imaging with CT chest, abdomen, and pelvis, and bone scan every 3 cycles. Eligibility criteria: Patients must have chest wall involvement from breast cancer, with or without distant metastases. Patients may have triple-negative breast cancer, hormone receptor positive, HER2- disease (after two prior lines of hormone therapy), or refractory HER2 positive disease. Patients may have received any number of lines of prior chemotherapy. A prior platinum is allowed as long as there was not disease progression on this agent. Specific Aims: 1. (Primary aim) Disease control rate in the chest wall and other distant sites at 18 weeks of treatment using RECIST 1.1 criteria, 2. progression-free survival, 3. toxicity, 4. response based on tumor PD-L1 expression, and 5. response based on irRECIST. Exploratory aims include evaluating: 1. Soluble PD-L1 expression, 2. changes in tumor and peripheral blood immune composition, 3. peripheral blood circulating tumor cells, 4. peripheral blood cell-free DNA, and 5. the association of MYC with PD-1 and TIM-3 on tumor cells, based on preclinical data to suggest that MYC may upregulate these inflammatory markers. Statistical Methods: 84 patients (56 in Arm A and 28 in Arm B) are being enrolled at 7 sites in the Translational Breast Cancer Research Consortium. The study is powered to determine a 20% difference in disease control rates between arms (HR 0.52, α= 0.10, ß=0.20). A futility analysis was originally planned to occur for Arm B after 18 patients are enrolled, but a subsequent amendment has enabled an earlier assessment after 14 patients were enrolled. Accrual: Present accrual is 40 patients. (NCT03095352). This trial is funded in part by Merck and a Development Program Grant from the University of California San Francisco. Contact information: Neelima Vidula, MD, Massachusetts General Hospital, nvidula@mgh.harvard.edu Citation Format: Neelima Vidula, Rita Nanda, Kathy Miller, Paula Pohlmann, Vandana Abramson, Leisha A. Emens, Ben H. Park, Minetta C. Liu, Andrei Goga, Hope S. Rugo. Translational breast cancer research consortium 044 trial: Randomized phase 2 study of pembrolizumab and carboplatin versus carboplatin alone for chest wall recurrence of breast cancer [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 OT-13-09.

Abstract PD5-08: The human tumor atlas network (HTAN) breast pre cancer atlas: A multi-omic integrative analysis of ductal carcinoma in situ (DCIS) and correlation with clinical outcomes

Abstract Introduction. As nonobligate precursors of invasive disease, pre-cancers provide a unique vantage point from which to study the molecular pathways and evolutionary dynamics that lead to the development of life-threatening cancers. Ductal carcinoma in situ (DCIS) is the most commonly diagnosed precursor of breast cancer, with variable propensity for invasive progression. In order to address the problems of over- and under-treatment, we performed a multimodal, integrated profile of DCIS with clinical outcomes with which to develop and validate predictors of invasive progression. Methods. We present observations on DNA, RNA, and protein expression on two independent patient cohorts of DCIS, diagnosed from 1981 to 2014, from the Translational Breast Cancer Research Consortium (TBCRC 038) and the Washington University Repository of Archival Human Breast Tissue (RAHBT). Patients initially diagnosed with DCIS, with either DCIS or invasive recurrence (cases; mean follow up 5.8 years) were matched to those without recurrence (controls; mean follow up 10.3 years), based upon age at diagnosis and year of diagnosis. Results. We present genomic and cellular changes that correlate with both disease states and patient outcomes in DCIS. DCIS can be clustered by classification systems developed for IBC. Specific immune cell types and pathways correlate with longitudinal outcome. Luminal cell adhesion and metabolism pathways are upregulated in controls and cases, respectively. Highly multiplexed ion beam imaging (MIBI) was used to validate RNA seq findings, and to provide single cell-level spatial context for molecular alterations.Conclusion. We have performed an integrated multi-omic analysis of DCIS and associated tumor micorenvironment. Our multi-scale approach employs in situ methods to generate a spatially resolved atlas of breast precancers where different modalities can be directly compared to each other, and correlated with conventional pathology findings and clinical outcome. The PreCancer Atlas represents a complex multi-modal database for DCIS study, whose design allows for future discovery and hypothesis generation. Table 1. Breast Pre-cancer Atlas Multi-scale Characterization AssaysAssayScaleType of DataIntegration and validation with other assaysRNA-seq (Single duct, single cell, TME)Cell, duct, organ, normal tissue1. Whole transcriptome gene expression profiling per single duct (also enabling CNV and cell type prediction)2. Whole transcriptome gene expression profiling per single duct1. Prediction of CNV confirmed by DNA-seq (single duct) and FISH (single cell)2. Prediction of cell type composition (Cibersort) confirmed by multiplex IHC and multicolor flow cytometryLow-pass whole genome DNA-seqDuct and adjacent normalCNV profiling per single ductAnalysis of CNV supported by RNA-seq (single duct) and MIBI (single cell)Whole genome sequencingDuct and adjacent normalMutation status per single ductMutational analysis confirmed by RNA-seqMultiplex IHC (MIBI &amp; Cyclic multicolor)Cell1. Cell type2. Proteomic analysisAnalysis of cell type supported by RNA-seq of ducts (Cibersort) and single cellsH&amp;E MorphometricsCell, duct, organSpatial location of cell types, organization of ductsAnalysis of H&amp;E images correlated with FISH data Citation Format: Shelley Hwang, Siri H Strand, Belen Rivero, Lorraine King, Tyler Risom, Bryan Harmon, Fergus Couch, Kristalyn Gallagher, Mark Kilgore, Shi Wei, Angela DeMichele, Tari King, Priscilla McAuliffe, Julie Nangia, Ana Maria Storniolo, Alastair Thompson, Gaorav Gupta, Joanna Lee, Jennifer Tseng, Robyn Burns, ChunFang Zhu, Magda Matusiak, Shirley X Zhu, Jason Wang, Jose Seoane, Jen Tappenden, Daisy Ding, Dadong Zhang, Jingqin Luo, Sujay Vennam, Sushama Varma, Lunden Simpson, Luis Cisneros, Timmothy Hardman, Lauren Anderson, Cody Straub, Sucheta Srivastava, Deb J Veis, Christina Curtis, Rob Tibshirani, Robert Michael Angelo, Allison Hall, Kouros Owzar, Kornelia Polyak, Carlo Maley, Jeff Marks, Graham Colditz, Robert B West. The human tumor atlas network (HTAN) breast pre cancer atlas: A multi-omic integrative analysis of ductal carcinoma in situ (DCIS) and correlation with clinical outcomes [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 PD5-08.

CTNI-02. TBCRC049: A PHASE II STUDY TO ASSESS THE SAFETY AND EFFICACY OF THE COMBINATION OF TUCATINIB, TRASTUZUMAB AND CAPECITABINE FOR THE TREATMENT OF LEPTOMENINGEAL METASTASIS IN HER2 POSITIVE BR1AST CANCER

Abstract Treatment options for patients with leptomeningeal metastasis (LM) from HER2-positive breast cancer (HER2+ BC) are limited and prognosis is poor. Tucatinib is an oral, potent, HER2 specific tyrosine kinase inhibitor with good tolerability and combinatory anti-tumor activity, including partial responses in heavily treated patients and those with brain metastases (BM). This is a phase 2 single-arm study to evaluate the efficacy of tucatinib, trastuzumab and capecitabine in HER2+ BC with newly-diagnosed LM. CNS disease will be evaluated at screening and every 6 weeks by neuroaxis MRI, CSF cytology, and neurological assessments per RANO-LMD (adapted) and RANO-BM criteria. Extra-CNS disease will be evaluated at screening and every 12 weeks by CT scan per RECIST criteria. All patients will be followed for survival. Symptom burden and quality of life assessments, as well as correlative blood and CSF samples, will be collected. Eligible patients include adults with HER2+ BC, KPS &amp;gt; 50, and newly-diagnosed, untreated LM (defined as positive CSF cytology and/or radiographic evidence of LM, plus clinical signs/symptoms). Patients with treated or concurrent/new BM are allowed. Patients treated with capecitabine within the last 12 months are excluded. This study has a Gehan-like design with an interim futility analysis and overall intent to estimate OS. For the interim analysis, success is defined as CNS PFS for 12 weeks. Enrollment will end if fewer than two successes are observed in the first 15 patients. Secondary endpoints include safety, CNS PFS at 12 weeks, RR in CNS and extra-CNS, and symptom burden/quality of life. The regimen will be considered worthy of future study if the median OS is &amp;gt; 4.4 months. Fourteen of 30 patients have accrued thus far. The study is active at multiple Translational Breast Cancer Research Consortium sites around the country.

Immunotherapy and chemotherapy combination for chest wall disease: TBCRC 044 trial.

TPS1114 Background: Immunotherapy combined with chemotherapy is being studied in metastatic breast cancer, and may have durable outcomes. Chest wall recurrence represents a difficult to treat subtype of breast cancer with a poor prognosis, with lymphovascular invasion in the primary tumor a significant risk factor. Given the inflammatory nature of this disease and the association of programmed cell death 1 (PD-1) expression with lymphovascular invasion, we hypothesized that the combination of pembrolizumab, an anti-PD-1 antibody, with carboplatin may be effective as treatment for breast cancer chest wall recurrences. Methods: This randomized phase II study is enrolling 84 patients with breast cancer involving the chest wall, who may also have distant metastases. Patients receive treatment with pembrolizumab 200 mg and carboplatin AUC 5 every 3 weeks for 6 cycles (Arm A, n = 56) followed by maintenance pembrolizumab +/- carboplatin (Arm Ax), or carboplatin AUC 5 every 3 weeks for 6 cycles (Arm B, n = 28) with an option to cross-over to pembrolizumab +/- carboplatin on progression (Arm Bx). Patients with all disease subtypes, triple-negative, hormone receptor positive/HER2- after 2 prior lines of hormone therapy, and HER2+ disease (with the option to continue trastuzumab) are eligible, with no limit on the number of prior therapies. Prior platinum chemotherapy is allowed in the absence of overt disease progression. Patients undergo clinical assessment with every cycle of treatment including chest wall photography, scans (CT chest, abdomen, and pelvis) every 2 cycles, and have peripheral blood and chest wall biopsies collected at baseline and the start of cycle 3 for correlative studies. The primary endpoint is the disease control rate in the chest wall and distant sites at 18 weeks of treatment based on RECIST 1.1. The study is powered to determine a 20% difference in disease control between arms (hazard ratio 0.52, α = 0.10, β = 0.20). Additional endpoints include response by tumor programmed death ligand 1 (PD-L1) status and irRECIST, progression-free survival, and toxicity. Chest wall tumor samples will be analyzed for changes in tumor immune composition, and PD-L1 and MYC oncogene expression, based on preclinical data to suggest that PD-L1 may be upregulated by MYC. Peripheral blood samples will be evaluated for changes in PD-L1 expression, cell-free DNA, and circulating tumor cells with treatment. The study is enrolling patients at 7 sites within the Translational Breast Cancer Research Consortium (TBCRC), with current enrollment of 38/84 patients. Clinical trial information: NCT03095352 .

A phase II trial of atezolizumab (anti-PD-L1) with carboplatin in patients with metastatic triple-negative breast cancer (mTNBC).

TPS1112 Background: Patients with metastatic triple negative breast cancer (mTNBC) have limited treatment options. Recent studies with a PD-L1 inhibitor and taxane based chemotherapy have demonstrated an increase in median progression free survival (PFS) in mTNBC. While taxanes target microtubules, platinum agents directly alkylate DNA and may generate additional neoantigens to enhance anti-tumor immunity via immune checkpoint inhibition. In this study, we are evaluating the combination of carboplatin with and without atezolizumab in patients with mTNBC. Serial biopsies are poised to help elucidate biological differences in responders and nonresponders. As optimal timing of adding checkpoint inhibition to chemotherapy is debatable, the randomized, crossover design will give insight into whether priming mTNBCs with DNA damaging chemotherapy results in cellular and immune changes that lead to a greater likelihood of response. Methods: This is a randomized phase II multicenter study at seven sites within the Translational Breast Cancer Research Consortium (TBCRC). Patients with mTNBC, ECOG 0-1, and 0-1 prior regimens for mTNBC are eligible. 106 patients will be randomized 1:1 to receive atezolizumab 1200 mg plus carboplatin AUC 6 (n = 53; Arm A) or carboplatin AUC 6 alone (n = 53; Arm B) every 3 weeks until intolerable toxicity or disease progression occurs. Patients receiving carboplatin alone have the option to cross over to atezolizumab upon progression (Arm Bx). Patients will undergo clinical assessment every cycle, and tumor assessment every 3 cycles with CT scan of the chest, abdomen, and pelvis and bone scan. Core biopsies of a metastatic lesion are performed at baseline and at progression. The primary endpoint is median progression free survival (PFS) with 95% confidence intervals based on RECIST 1.1. The sample size of 106 with 1:1 randomization is powered to detect a 1.5-month difference in PFS between arms (α = 0.10, β = 0.20). Secondary endpoints include overall response rate (ORR), duration of response (DOR), clinical benefit rate, and overall survival. The PFS, ORR, and DOR will also be measured by irRECIST to account for delayed effects of atezolizumab on tumor burden. The quantification of tumor infiltrating lymphocytes (TILs) will study the prognostic effects of TILs on PFS in patients receiving atezolizumab. Biopsy-derived PD-L1 expression by IHC and RNA-seq will assess treatment-induced changes, define triple-negative subtypes, and evaluate for resistance mechanisms. To date, 89 of 106 patients are enrolled. Clinical trial information: NCT03206203 .

Abstract OT2-04-05: Pembrolizumab in combination with carboplatin versus carboplatin alone in breast cancer patients with chest wall disease: Translational Breast Cancer Research Consortium (TBCRC) 44 trial

Abstract Background: Chest wall recurrence can occur as a complication of breast cancer. This type of breast cancer is difficult to treat with short-lived responses to therapy, and associated with the development of distant metastases. Better therapies are needed in this setting. Immune checkpoint inhibition is being explored in breast cancer, with an immunotherapy agent currently approved for triple-negative breast cancer (TNBC). We hypothesize that pembrolizumab, an anti-programmed cell death 1 (PD-1) antibody, may be effective in treating chest wall recurrence of breast cancer given the inflammatory nature of this disease and high expression of PD-1 seen in tumors with lymphovascular invasion that may predispose patients to chest wall recurrence. Platinum chemotherapy may augment anti-tumor immunity, with the combination of pembrolizumab and carboplatin shown to be effective in advanced lung cancer. This study is evaluating the efficacy of pembrolizumab and carboplatin for breast cancer patients with chest wall disease. Methods: In this phase II study, 84 patients are being randomized 2:1 to treatment with pembrolizumab in combination with carboplatin (Arm A) versus carboplatin alone (Arm B) with an option to cross over to pembrolizumab alone (Arm Bx) on progression. Pembrolizumab is dosed at 200 mg IV every 3 weeks, and carboplatin is dosed at AUC 5 IV every 3 weeks. Patients may have TNBC, hormone receptor positive (HR)+/HER2- breast cancer that has progressed on 2 prior lines of hormone therapy, or refractory HER2+ breast cancer (may continue herceptin). Patients may have distant metastases, but must have surgically unresectable disease. Prior chest wall radiation is allowed. The primary endpoint is to determine the disease control rate (chest wall and distant sites) at 18 weeks of treatment. Patients undergo chest wall assessments with photography of skin lesions with every cycle of treatment, and imaging (CT chest, abdomen, and pelvis, and bone scan) every 2 cycles to evaluate for progression. The study is powered to determine a 20% difference in disease control rates between arms A and B (hazard ratio of 0.52, α= 0.10, β= 0.20). Secondary endpoints include response stratified by tumor programmed death ligand 1 (PD-L1) expression, progression free survival, response by irRECIST, and toxicity. The study incorporates many translational studies using chest wall biopsy tissue collected at baseline and after 2 cycles of treatment, as well as correlative blood tests, including assessing changes in tumor and blood PD-L1 expression, circulating cell-free DNA, circulating tumor cells, soluble PD-L1 expression, and changes in the expression of MYC, an oncogene that may upregulate the expression of PD-1. Patients are currently being enrolled at 7 sites in the TBCRC. As of July 2019, 30 patients are enrolled. This study is supported by Merck and the TBCRC. (NCT03095352). Citation Format: Neelima Vidula, Rita Nanda, Kathy Miller, Vandana Abramson, Paula Pohlmann, Adam Brufsky, Ben Park, Minetta Liu, Andrei Goga, Hope S. Rugo. Pembrolizumab in combination with carboplatin versus carboplatin alone in breast cancer patients with chest wall disease: Translational Breast Cancer Research Consortium (TBCRC) 44 trial [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr OT2-04-05.