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Background: The introduction of immune checkpoint inhibitors (ICI) to standard neoadjuvant chemotherapy regimens has been shown to significantly improve outcomes in patients with triple negative breast cancer and is being investigated for high-risk hormone receptor-positive (HR+)/human epidermal growth factor-2 negative (HER2-) breast cancer. Preclinical evidence suggests radiation therapy (RT) can stimulate intra-tumoral T cell infiltration and enhance the expression and immune detection of tumor-specific neoantigens. This phase II pilot randomized study (NCT04443348) aims to evaluate the safety and efficacy of two different doses of preoperative primary tumor RT boost when combined with neoadjuvant pembrolizumab, then followed by standard neoadjuvant chemotherapy. Dual co-primary endpoints include determining the pathologic complete response (pCR) rate in the non-irradiated and pathologically confirmed metastatic axillary lymph node(s) in each treatment arm and quantifying tumor-infiltrating T lymphocytes in on-treatment (C1D14) tumor biopsies. We hypothesize that high-dose RT will increase the proportion of tumors with high T cell infiltration (i.e., top quartile) from 25% to 55%. Secondary endpoints include measuring residual cancer burden, evaluating tolerability of the regimen, and assessing quality of life. Exploratory endpoints include evaluation of treatment-associated changes in the tumor immune microenvironment, circulating immune cell analyses, and circulating tumor DNA kinetics. Methods: The study plans to enroll 128 participants with either triple negative (n=80) or high-risk HR=/HER2- (n=48) breast cancer who will be randomized to receive no, low (9 Gy), or high (24 Gy) dose of preoperative RT boost, after which 24 participants of either breast cancer subtype will be enrolled to an exploratory high dose proton therapy boost cohort. The eligibility criteria include patients who have biopsy-proven, axillary lymph node-positive breast cancer that is either triple negative (defined as ER< 10%, PR< 10%, and HER2-negative) or high-risk HR+/HER2- (grade III or having a high-risk genomic assay score). Study treatment is given in 6-week cycles, with 400 mg Pembrolizumab given on day 1 of each cycle. For those participants randomized to receive a preoperative RT boost, treatment is delivered in 3 fractions (3 × 3 Gy or 3 × 8 Gy) over consecutive business days, where one of the fractions is given on the same day as C1D1 Pembrolizumab. Standard neoadjuvant chemotherapy begins on C1D15 with paclitaxel (plus carboplatin for triple negative) administered weekly for 12 weeks, and then starting on C3D15, dose-dense doxorubicin/cyclophosphamide is administered every 2 weeks for 8 weeks. Following neoadjuvant treatment, participants will receive standard breast surgery (including removal of the pathologically confirmed metastatic lymph node) followed by adjuvant pembrolizumab, radiation therapy, and standard-of-care systemic therapy as clinically indicated. Tissue samples from the primary tumor and biopsy-proven lymph node are taken at baseline, C1D14, and at the time of surgery. There are eleven blood collection timepoints throughout the neoadjuvant and adjuvant settings. Participants will be followed for 2 years after surgery to assess safety and durability of responses. Results: This study has accrued 12 participants to date, including 10 with triple negative breast cancer and 2 with high-risk HR+/HER2- breast cancer. Formal results for this study are forthcoming, as the trial is actively accruing at 6 institutions, with plans to open at 3 more within the year. For persons with a specific interest in this trial, please contact Joseph Connolly, Multi-Center Coordinator, at jconnolly28@mgh.harvard.edu. Citation Format: Joseph J. Connolly, Laura M. Spring, Alphonse G. Taghian, Michele Gadd, Laura Warren, Ana C. Garrido-Castro, Tari King, Elizabeth A. Mittendorf, Jose P. Leone, Dana L. Casey, Lisa Carey, Tiffany A. Traina, Yara Abdou, Atif Khan, George Plitas, Jean Wright, Cesar Augusto Santa-Maria, Lisa Jacobs, Rachel Blitzblau, E Shelley Hwang, Carey Anders, Ian Krop, Antonio C. Wolff, Alastair M. Thompson, Elyssa Denault, Gaorav Gupta, Alice Ho. TBCRC-053: P-RAD: A Randomized Study of Preoperative Chemotherapy, Pembrolizumab and No, Low or High Dose RADiation in Node-Positive, HER2-Negative Breast Cancer [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 OT3-15-01.

Background: The prognosis for advanced/metastatic triple negative breast cancer (TNBC) remains poor and novel therapeutic strategies are urgently needed to improve outcomes. Insulin resistance and obesity contribute to cancer progression and are independent predictors of worse survival after TNBC diagnosis. Chemotherapy worsens insulin resistance, body mass index, and multiple other metabolic parameters which can paradoxically limit treatment efficacy and survival. Methionine aminopeptidase 2 (MetAP2/p67) is overexpressed in many tumor types and MetAP2 inhibitors exhibit broad anti-tumor activity. Additionally, MetAP2 inhibitors improve insulin resistance, reduce adiposity, and normalize levels of adipokines, attenuating the effects of metabolic dysfunction on tumor growth. Evexomostat (SDX-7320) is a second-generation MetAP2 inhibitor designed to improve drug-like properties and minimize central nervous system toxicities. Evexomostat improved insulin sensitivity, reduced fat mass and normalized adipokine levels in preclinical models of obesity, and reduced tumor growth in preclinical models of TNBC. In phase 1 trials, MetAP2 inhibition combined with chemotherapy was safe and well tolerated, while evexomostat monotherapy partially restored insulin sensitivity, reduced angiogenic factors as well as adipokines and showed anti-metastatic effects in patients with advanced solid tumors. The goal of this phase 2 study is to test whether evexomostat in combination with eribulin chemotherapy prevents worsening of insulin resistance and augments tumor response in patients with metastatic TNBC and concomitant metabolic dysfunction. Methods: This is a single-center, placebo-controlled phase 2 randomized control trial of evexomostat, a MetAP2 inhibitor, in combination with eribulin chemotherapy. Eligible patients must have histologically confirmed metastatic TNBC, measurable disease or ≥1 predominantly lytic bone lesion, baseline metabolic dysfunction defined as hemoglobin A1c >5.5% and/or BMI ≥30 kg/m2, have received ≤2 prior lines of therapy in the advanced/metastatic setting, have ECOG performance status ≤1, and adequate organ function. Patients with uncontrolled or insulin-dependent type II diabetes, or who require combination antihyperglycemic therapy are excluded. During the safety run-in period, 15 patients will be assigned to receive evexomostat 49 mg/m2 every 2 weeks in combination with eribulin 1.4 mg/m2 administered on days 1 and 8 of a 21-day cycle. Upon safety confirmation, an additional 40 patients will be randomized 2:1 to receive evexomostat or placebo in combination with eribulin. The primary endpoint is metabolic efficacy assessed by change in Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) score. Secondary endpoints include objective response rate, progression-free survival, duration of response, safety and tolerability, patient-reported outcomes, changes in metabolic markers, and changes in body composition parameters. Historically, HOMA-IR scores double during chemotherapy, and this trial will test whether evexomostat will attenuate the expected rise in HOMA-IR. Specifically, the trial will have >90% power to detect a difference between a 1.5-fold change in HOMA-IR in the control arm versus no change in the investigational arm while controlling the Type I error at 5%. This trial opened to accrual in July 2022. A total accrual of 61 patients is planned with a goal of 55 evaluable patients. For any inquiries/questions, please contact Sherry Shen at shens1@mskcc.org. Clinical trial registry number: pending Funding, study drug evexomostat and other support provided by: SynDevRx, Inc. Citation Format: Sherry Shen, Anna Whalen, Mark E. Robson, Larry Norton, Tiffany A. Traina, Neil M. Iyengar. The ARETHA Study: A phase 2 randomized control trial of Eribulin with Evexomostat (SDX-7320) or placebo for patients with metastatic triple-negative breast cancer and metabolic dysfunction [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 OT2-17-02.

Background. Patients (pts) with early triple negative breast cancer (eTNBC) are at increased risk of breast cancer recurrence and death. Recent studies have focused on escalation of therapy, with current treatment standard of at least five drugs – and associated toxicities - for eTNBC. Though presence of residual disease after neoadjuvant therapy (NAT) as measured by residual cancer burden (RCB) helps guide addition of adjuvant treatment, more effective tools to tailor therapy are limited. Persistence of circulating tumor DNA (ctDNA) in the setting of residual disease is associated with high risk of distant recurrence. However, more sensitive minimal residual disease (MRD) assays are needed to potentially guide optimization of systemic therapy. Methods. TBCRC 030 is a phase II randomized study of 12 weeks of NAT single agent cisplatin or paclitaxel for stage II-III TNBC, followed by surgery. The primary objective of the parent study was to correlate baseline biomarker for homologous recombination deficiency and RCB by study arm. From this group, responders (RCB 0/1) and non-responders (RCB 2/3) from both study arms who did not receive additional NAT prior to surgery were selected for analysis from the study cohort, matched on baseline nodal status and tumor size. As a post hoc study amendment, available pts were followed for event free survival (EFS). Plasma samples were collected prior to treatment initiation (W0), at three weeks (W3), and at twelve weeks, prior to surgery (W12). Whole genome sequencing (WGS) was performed on primary tumor tissue to identify somatic mutations and design for each pt a tumor-informed, ctDNA assay tracking up to 1000 mutations to detect MRD. Detection limit was computed for each tested sample as previously described. For each sample assayed, we report tumor fraction (TFx) when MRD was detected and the detection limit at 90% power when MRD was not detected. Results. Of 139 study pts, 68 had complete tissue and plasma samples and no receipt of additional NAT. Of these, 22 were responders. These responders, and 22 matched non-responders were identified for analysis. Data from 22 pts – 11 responders, 11 non-responders - are described here; full analysis on all 44 pts will be presented at the meeting. Personalized ctDNA assays were designed targeting 434 to 1000 variants (median 1000) and applied to 66 plasma samples. At W0, 100% (22/22) were positive for ctDNA; 73% (16/22) and 55% (12/22) were positive at W3, and W12, respectively. In pts with T1-T2 tumors median TFx was 4.1e-3(7.8e-6, 3.4e-2) and 4.7e-1(4.3e-2, 9.0e-1) in pts with T3-T4 tumors. TFx decreased from W0 to W3 and from W0 to W12 in responders (Table 1). By W12, ctDNA had cleared in 7/8 pts with RCB 0, 1/3 with RCB 1, 2/8 with RCB 2, and 0/3 with RCB 3. Overall, ctDNA levels were broad with median TFx of 1.5e-3 (range 2.9e-6 to 0.90). Detection limit at 90% power for all tested samples was a median of 8.8e-6 (range 9.9e-7 to 6.8e-3). To investigate whether ctDNA persistence after NAT was associated with BC recurrence, we analyzed a separate group of all 8 pts with known recurrence and with complete data and samples. All pts had persistent ctDNA at W12 (median TFx 6.8e-3, [2.9e-6 to 6.6e-2]). Conclusions. After 3 weeks of NAT for eTNBC, ctDNA TFx decreased, with a 3900-fold change in responders and 18-fold change in non-responders. By W3, TFx for most pts with RCB 0/1 were below the 1 in 10,000 limit of detection for many currently available assays, emphasizing the need for sensitive tests to potentially guide therapy. Additional studies will determine if ctDNA-guided approaches in eTNBC can improve pt outcomes. Table 1: Tumer Fraction and Tumer Fraction Fold Change by Response to Neoadjuvant Therapy Citation Format: Heather A. Parsons, Timothy Blewett, Xiangying Chu, Sainetra Sridhar, Katheryn Santos, Kan Xiong, Vandana Abramson, Ashka Patel, Ju Cheng, Adam M. Brufsky, Justin Rhoades, Jeremy Force, Ruolin Liu, Tiffany A. Traina, Lisa Carey, Mothaffar Rimawi, Ahmed Elkhanany, Vered Stearns, Jennifer M. Specht, Harold Burstein, Antonio C. Wolff, Eric Winer, Nabihah Tayob, Ian Krop, Todd Golub, Erica L. Mayer, Viktor Adalsteinsson. PD11-06 Circulating tumor DNA association with residual cancer burden after neoadjuvant therapy in triple negative breast cancer in TBCRC 030 [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 PD11-06.

Background: Providers and patients alike are unaware of the racial disparities that exist in triple-negative breast cancer (TNBC), which occurs at twice the rate in women of the African Diaspora (WAD) compared to White American women. WAD tend to be diagnosed at a more advanced stage, use under-resourced health care settings or encounter bias in their care, and experience higher rates of TNBC-related mortality. An historically difficult-to-treat breast cancer subtype, the TNBC landscape is changing with an influx of clinical data and newly approved treatments. An educational initiative was designed to heighten awareness of new therapies, including antibody drug conjugates, empower patients in their care, and to align on addressing disparities in TNBC care. Methods: Two, 1-hour online, interactive, video-based programs were designed for patients and providers. The patient/caregiver program was hosted on CancerCoachLive in April, 2022 and the provider program on OMedLive in May, 2022 and remains on-demand until May 2023. With a focus on addressing disparities in care, 78% of patients/caregivers attending the patient program were of African descent. The initiative was conducted in collaboration with TOUCH, the Black Breast Cancer Alliance and the National Breast Cancer Foundation. Four real-world patient accounts of TNBC navigation and management were embedded in the patient program; and represented women of Caucasian, African, and Native American ethnicity. While practice and knowledge gaps among HCPs, and knowledge gaps of patients were assessed, we report on the analysis of ‘tethered’, behavioral, practice pattern, and perception questions assessed across the patient and provider programs. Results: As of June 2022, 200 providers and 29,389 patients/caregivers participated in the ongoing activities. Post education, participants in the provider program anticipated the education would positively impact practice behavior (86%) while patients/caregivers reported greater confidence in discussions with their treatment team (92%). Pre- and post-evaluation of strategies addressing disparities revealed improvements in ‘ensuring access to care through integration of care coordinators or social worker as part of the healthcare team.’ Provider assessment of barriers to enrollment in clinical trials uncovered the top barrier as ‘lack of trials at my institution’ (33%) and the top barrier to integration of new therapies as ‘lack of knowledge regarding evidence-based strategies’ (44%). Misalignments in patient-provider perceptions were observed. ‘Patient lack of interest’ was a provider-identified barrier to clinical trials, yet 60% of patients/caregivers reported that they were ‘very likely’ to participate in a clinical trial if eligible. Similarly, differences were seen in the ranking of topics of highest interest regarding treatment decisions. Lastly, patient- vs provider-identified care challenges were not aligned. Themes from the real-world patient accounts provided greater context for the misalignments observed. Conclusions: Assessment and alignment of patient-provider care perceptions has potential to impact clinical practice behaviors, patient/caregiver communication and confidence, and treatment/clinical trial knowledge for effective TNBC management. This educational partnership facilitated assessment of attitudes, perceptions, and barriers to care that can further guide how disparities in care for patients with TNBC are addressed. This ‘tethered’ approach to education was successful in empowering patients in shared decision-making, initializing changes in clinical practice, and gaining patient-provider insights in TNBC management. This activity was supported by an educational grant from Gilead Sciences, Inc Citation Format: Tariqa Ackbarali, Ricki Fairley, Tiffany A. Traina. Uncovering gaps in patient-provider perceptions of triple-negative breast cancer care: Addressing disparities through education-advocacy partnerships [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 P6-08-06.

Introduction: Despite recent treatment advances, the prognosis for patients diagnosed with locally recurrent inoperable or metastatic triple-negative breast cancer (TNBC) remains poor. Single-agent chemotherapy has been the mainstay of treatment for metastatic TNBC for many years, with very limited treatment options for patients who are not candidates for anti-PD-1/PD-L1 therapy; consequently, there remains an urgent unmet need. Trophoblast cell surface protein 2 (TROP2) is a type I transmembrane glycoprotein highly expressed on various solid tumors, including breast. Datopotamab deruxtecan (Dato-DXd) is an antibody-drug conjugate (ADC) composed of a humanized anti-TROP2 IgG1 monoclonal antibody covalently linked to an exatecan derivative (DXd) – a highly potent topoisomerase I inhibitor payload – via a stable, tumor-selective, tetrapeptide-based cleavable linker. Dato-DXd has previously been evaluated in TROPION-PanTumor01 (NCT03401385) – an ongoing Phase I clinical trial across multiple advanced solid tumors, including heavily-pretreated, metastatic TNBC. As of the July 30, 2021 cut-off date, the objective response rate (ORR) by blinded independent central review (BICR) was 34% (15/44) in all patients with TNBC and 52% (14/27) in those patients treatment-naïve to topoisomerase I inhibitor-based ADC therapies, with measurable disease (per RECIST 1.1) at baseline. Furthermore, a manageable safety profile was reported, with no new safety signals identified; low grade nausea and stomatitis were most frequent, with neutropenia and diarrhea being uncommon. The aim of the phase 3 TROPION-Breast02 trial is to evaluate the efficacy and safety of Dato-DXd versus investigator’s choice of chemotherapy (ICC) in patients with TNBC who are not candidates for PD-1/PD-L1 inhibitor therapy. Methods: TROPION-Breast02 (NCT05374512) is an ongoing Phase 3, open-label, randomized study of Dato-DXd versus ICC in first-line treatment of patients with locally recurrent inoperable or metastatic TNBC. Approximately 600 patients will be randomized 1:1 to receive either Dato-DXd 6 mg/kg IV every three weeks or ICC (paclitaxel, nab-paclitaxel, carboplatin, capecitabine, or eribulin mesylate). Patients ≥18 years with histologically/cytologically confirmed TNBC who have not received prior chemotherapy or targeted systemic therapy for metastatic or locally recurrent inoperable disease are eligible for inclusion. Patients are also required to have an ECOG PS of 0 or 1 and be eligible for treatment with one of the ICC options per investigator assessment. Patients must have ≥1 measurable lesion per RECIST v1.1 not previously irradiated, along with a formalin-fixed and paraffin-embedded tumor sample available. Those with a previously treated neoplastic spinal cord compression or clinically inactive brain metastases can be included. Key exclusion criteria are history of another primary malignancy; persistent toxicity from previous anti-cancer treatments; uncontrolled infections; current/prior interstitial lung disease/pneumonitis or clinically severe pulmonary function compromise; clinically significant corneal disease; and prior treatment with topoisomerase I inhibitors, TROP2-targeted therapy, or the same chemotherapy agent chosen for on-study ICC. The dual primary endpoints are progression free survival (PFS) per RECIST 1.1 by BICR, and OS. Secondary endpoints include ORR, duration of response, PFS by investigator assessment, time to deterioration for patient-reported outcomes, time to first subsequent therapy, time to second subsequent therapy, time to second progression or death, pharmacokinetics and immunogenicity of Dato-DXd, and safety. Recruitment for this study is ongoing as of June 2022. Citation Format: Rebecca Dent, David W. Cescon, Thomas Bachelot, Kyung Hae Jung, Zhi-Ming Shao, Shigehira Saji, Tiffany A. Traina, Petra Vuković, Darlington Mapiye, Micah Maxwell, Peter Schmid, Javier Cortés. TROPION-Breast02: Phase 3, open-label, randomized study of first-line datopotamab deruxtecan versus chemotherapy in patients with locally recurrent inoperable or metastatic TNBC who are not candidates for anti-PD-(L)1 therapy [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr OT1-03-05.

Supplementary Figure 1 - PDF file 44K, Supplementary Figure 1A-D. Median hormone levels at baseline, C2 and EOS

Supplementary Table S1. Pharmacokinetic parameters for enzalutamide administered as a single oral dose administered on day 1 to women with breast cancer and and on day 49 to men with prostate cancer; Supplementary Table S2. Pharmacokinetic parameters for enzalutamide and its active metabolite in patients taking enzalutamide 160 mg once daily to steady state; Supplementary Table S3. Most common grade ≥3 adverse events in more than one patient in the safety population.

Relationships between aromatase inhibitor plasma exposures (AUCtau) and concentrations of (A, B) estradiol and (C, D) estrone in individual patients. Red lines indicate expected estrogen levels with anastrozole or exemestane use

Purpose: Tigatuzumab (TIG), an agonistic anti-DR5 antibody, triggers apoptosis in DR5+ human tumor cells without crosslinking. TIG has strong in vitro/in vivo activity against basal-like breast cancer cells enhanced by chemotherapy agents. This study evaluates activity of TIG and chemotherapy in patients with metastatic triple-negative breast cancer (TNBC).Experimental Design: Randomized 2:1 phase II trial of albumin-bound paclitaxel (nab-PAC) ± TIG in patients with TNBC stratified by prior chemotherapy. Patients received nab-PAC weekly × 3 ± TIG every other week, every 28 days. Primary objective was within-arm objective response rate (ORR). Secondary objectives were safety, progression-free survival (PFS), clinical benefit, and TIG immunogenicity. Metastatic research biopsies were required.Results: Among 64 patients (60 treated; TIG/nab-PAC n = 39 and nab-PAC n = 21), there were 3 complete remissions (CR), 8 partial remissions (PR; 1 almost CR), 11 stable diseases (SD), and 17 progressive diseases (PD) in the TIG/nab-PAC arm (ORR, 28%), and no CRs, 8 PRs, 4 SDs, and 9 PDs in the nab-PAC arm (ORR, 38%). There was a numerical increase in CRs and several patients had prolonged PFS (1,025+, 781, 672, 460, 334) in the TIG/nab-PAC arm. Grade 3 toxicities were 28% and 29%, respectively, with no grade 4–5. Exploratory analysis suggests an association of ROCK1 gene pathway activation with efficacy in the TIG/nab-PAC arm.Conclusions: ORR and PFS were similar in both. Preclinical activity of TIG in basal-like breast cancer and prolonged PFS in few patients in the combination arm support further investigation of anti-DR5 agents. ROCK pathway activation merits further evaluation. Clin Cancer Res; 21(12); 2722–9. ©2015 AACR.See related article by Paoletti et al., p. 2771

Supplementary Data from PIK3CA Mutation Associates with Improved Outcome in Breast Cancer

Supplementary Legend - PDF file 22K, Supplementary Legend

Supplementary figure legends

Supplementary Figure 2 - PDF file 275K, Supplementary Figure 2A-D. Changes in hormone levels over time per patient; responders (stable disease >6 months) highlighted in red

Purpose: Several lines of evidence support targeting the androgen signaling pathway in breast cancer. Enzalutamide is a potent inhibitor of androgen receptor signaling. Preclinical data in estrogen-expressing breast cancer models demonstrated activity of enzalutamide monotherapy and enhanced activity when combined with various endocrine therapies (ET). Enzalutamide is a strong cytochrome P450 3A4 (CYP3A4) inducer, and ETs are commonly metabolized by CYP3A4. The pharmacokinetic (PK) interactions, safety, and tolerability of enzalutamide monotherapy and in combination with ETs were assessed in this phase I/Ib study.Experimental Design: Enzalutamide monotherapy was assessed in dose-escalation and dose-expansion cohorts of patients with advanced breast cancer. Additional cohorts examined effects of enzalutamide on anastrozole, exemestane, and fulvestrant PK in patients with estrogen receptor–positive/progesterone receptor–positive (ER+/PgR+) breast cancer.Results: Enzalutamide monotherapy (n = 29) or in combination with ETs (n = 70) was generally well tolerated. Enzalutamide PK in women was similar to prior data on PK in men with prostate cancer. Enzalutamide decreased plasma exposure to anastrozole by approximately 90% and exemestane by approximately 50%. Enzalutamide did not significantly affect fulvestrant PK. Exposure of exemestane 50 mg/day given with enzalutamide was similar to exemestane 25 mg/day alone.Conclusions: These results support a 160 mg/day enzalutamide dose in women with breast cancer. Enzalutamide can be given in combination with fulvestrant without dose modifications. Exemestane should be doubled from 25 mg/day to 50 mg/day when given in combination with enzalutamide; this combination is being investigated in a randomized phase II study in patients with ER+/PgR+ breast cancer. Clin Cancer Res; 23(15); 4046–54. ©2017 AACR.

Purpose: Circulating tumor cells (CTC) are prognostic in metastatic breast cancer (MBC). We tested whether EpCAM-based capture system (CellSearch) is effective in patients with triple-negative (TN) MBC, and whether CTC apoptosis and clustering enhances the prognostic role of CTC.Experimental Design: CTC enumeration and apoptosis were determined using the CXC CellSearch kit at baseline and days 15 and 29 in blood drawn from TN MBC patients who participated in a prospective randomized phase II trial of nanoparticle albumin-bound paclitaxel (nab-paclitaxel) with or without tigatuzumab. Association between levels of CTC and patient outcomes was assessed using logistic regression, Kaplan–Meier curves, and Cox proportional hazards modeling.Results: Nineteen of 52 (36.5%), 14 of 52 (26.9%), and 13 of 49 (26.5%) patients who were evaluable had elevated CTC (≥5 CTC/7.5 mL whole blood) at baseline and at days 15 and 29, respectively. Patients with elevated versus not elevated CTC at each time point had worse progression-free survival (PFS; P = 0.005, 0.0003, 0.0002, respectively). The odds of clinical benefit response for those who had elevated versus low CTC at baseline and days 15 and 29 were 0.25 (95% CI: 0.08–0.84; P = 0.024), 0.19 (95% CI: 0.05–0.17; P = 0.014), and 0.06 (95% CI: 0.01–0.33; P = 0.001), respectively. There was no apparent prognostic effect comparing CTC apoptosis versus non-apoptosis. Presence of CTC cluster at day 15 and day 29 was associated with shorter PFS.Conclusions: CTC were detected using CellSearch assay in approximately one-third of TN MBC patients. Elevated CTC at baseline and days 15 and 29 were prognostic, and reductions in CTC levels reflected response. Clin Cancer Res; 21(12); 2771–9. ©2015 AACR.See related article by Forero-Torres et al., p. 2722

Supplementary Figure 1-5. Supplementary Figure 1. Example of cluster image using the CellSearch® system. Supplementary Figure 2. REMARK diagram of the 19 patients who had elevated CTC (Group B/C) at baseline that were used to study "CTC-response". Supplementary Figure 3. PFS for TIG-treated patients versus the control group according to baseline CTC levels: CTC

Individual and mean plasma exposures (AUCtau or Cmin) to endocrine therapies alone or in combination with enzalutamide. Note: Box plots provide the mean (red line), median (black line), and 25%/75% quartiles with whiskers to the last point within 1.5-times interquartile range. Sample sizes are reported in Table 2 in the article.

CCR Translation for the Article from PIK3CA Mutation Associates with Improved Outcome in Breast Cancer

Purpose: In breast cancer, somatic mutations in the PIK3CA gene are common. The prognostic implication of these activating mutations remains uncertain as moderately sized studies have yielded variable outcomes. Our aim was to determine the prognostic implications of PIK3CA mutations in breast cancer.Experimental Design: Archival formalin-fixed paraffin-embedded primary breast tumors, from 590 patients selected for known vital status with a median follow-up of 12.8 years and a tumor >1 cm, were genotyped for PIK3CA mutations. Mutation rates and associations between mutation site and clinicopathologic characteristics were assessed. Progression-free survival, overall survival, and breast cancer–specific survival were examined using Kaplan-Meier or competing risk methodology.Results: PIK3CA mutation is identified in 32.5% of breast cancers. PIK3CA mutation significantly associates with older age at diagnosis, hormone receptor positivity, HER2 negativity, lower tumor grade and stage, and lymph node negativity. Patients with PIK3CA mutated tumors have significant improvement in overall survival (P = 0.03) and breast cancer–specific survival (P = 0.004). Analysis for PIK3CA mutation site-specific associations reveals that the H1047R kinase domain mutation highly associates with node negativity (P = 0.007), whereas helical domain hotspot mutations associate with older age at diagnosis (P = 0.004).Conclusion: This study defines the positive prognostic significance of PIK3CA mutations. This work is clinically relevant, as it will significantly affect the design of clinical trials planned for phosphatidylinositol 3-kinase–targeted therapy. Future work may define a population of older age breast cancer patients in whom therapy can be minimized. (Clin Cancer Res 2009;15(16):5049–59)

Supplementary Table 1 - PDF file 4K, Supplementary Table 1. Median hormone levels at baseline, start of cycle 2 (C2), and end of study (EOS) and the percent change in levels from baseline to C2 and C2 to EOS

1. Supplemental Data: Differential of Toxicity and Eligibility Critique.; 2. Supplemental Figure 1: Gene Expression in Patients With Response to Therapy.

Supplementary Table 1. Table illustrating the criteria with which a cell was considered viable, or apoptotic either due to positive M-30 staining and/or visual evidence of apoptosis (nucleic condensat). Legend: Y= Yes, N= No

Mutations in homologous recombination (HR) genes, including

PurposeTo examine circulating tumor DNA (ctDNA) and its association with residual cancer burden (RCB) using an ultrasensitive assay in patients with triple-negative breast cancer (TNBC) receiving neoadjuvant chemotherapy (NAT).Patients and MethodsWe identified responders (RCB-0/1) and matched non-responders (RCB-2/3) from the phase II TBCRC 030 prospective study of neoadjuvant paclitaxel vs. cisplatin in TNBC. We collected plasma samples at baseline, three weeks, and twelve weeks (end of therapy). We created personalized ctDNA assays utilizing MAESTRO mutation enrichment sequencing. We explored associations between ctDNA and RCB status and disease recurrence.ResultsOf 139 patients, 68 had complete samples and no additional NAT. Twenty-two were responders and 19 of those had sufficient tissue for whole-genome sequencing. We identified an additional 19 non-responders for a matched case-control analysis of 38 patients using a MAESTRO ctDNA assay tracking 319-1000 variants (median 1000) to 114 plasma samples from 3 timepoints. Overall, ctDNA positivity was 100% at baseline, 79% at week 3, and 55% at week 12. Median tumor fraction (TFx) was 3.7 × 10−4(range: 7.9 × 10−7to 4.9 × 10−1). TFx decreased 285-fold from baseline to week 3 in responders and 24-fold in non-responders. Week 12 ctDNA clearance correlated with RCB: clearance was observed in 10/11 patients with RCB-0, 3/8 with RCB-1, 4/15 with RCB-2, and 0/4 with RCB-3. Among 6 patients with known recurrence five had persistent ctDNA at week 12.ConclusionNAT for TNBC reduced ctDNA TFx by 285-fold in responders and 24-fold in non-responders. In 58% (22/38) of patients, ctDNA TFx dropped below the detection level of a commercially available test, emphasizing the need for sensitive tests. Additional studies will determine if ctDNA-guided approaches can improve outcomes.

Androgen receptor (AR) inhibitor therapy is a developing treatment for AR-positive breast cancer (BC) with ongoing clinical trials. AR splice variant-7 (AR-V7) is a truncated variant of AR that leads to AR inhibitor therapy resistance in prostate cancer; recent studies have identified AR-V7 in BC and theorized that AR-V7 can have a similar impact. This study assessed the prevalence and clinicopathologic features associated with AR-V7 in a large BC cohort. BC samples were evaluated by MSK-Fusion targeted RNAseq for AR-V7 detection and MSK-IMPACT targeted DNAseq, including triple-negative tumors with no driver alteration and estrogen receptor-positive/ESR1 wildtype tumors progressing on therapy. Among 196 primary and metastatic/recurrent cases (196 RNAseq, 194DNAseq), 9.7% (19/196) were AR-V7 positive and 90.3% (177/196) AR-V7 negative. All AR-V7 positive BC were AR-positive by immunohistochemistry (19/19). The prevalence of AR-V7 by receptor subtype (N = 189) was: 18% (12/67) in ER-/PgR-/HER2-negative BC, 3.7% (4/109) in ER-positive/HER2-negative BC, and 15.4% (2/13) in HER2-positive BC; AR-V7 was detected in one ER-positive/HER2-unknown BC. Apocrine morphology was observed in 42.1% (8/19) of AR-V7 positive BC and 3.4% (6/177) AR-V7 negative BC (P

Background: Chemotherapy remains the mainstay of treatment for early-stage triple negative breast cancer (TNBC), yet targetable drivers of interest are under investigation. A subset of TNBCs express the androgen receptor (AR) and exhibit androgen-dependent growth. The AR-antagonist enzalutamide (ENZA) has shown activity in patients with metastatic AR+ TNBC. In this study, the feasibility of adjuvant ENZA in early-stage, AR+ TNBC was assessed (NCT02750358). As reported previously, this study met its primary endpoint of feasibility (Traina et al., ASCO 2019). Here we report secondary survival endpoints. Methods: In this single-arm, open-label, multi-center trial, patients with stage I-III, AR≥1% TNBC (ER/PR Citation Format: Elaine M Walsh, Ayca Gucalp, Sujata Patil, Marcia Edelweiss, Dara S Ross, Pedram Razavi, Shanu Modi, Neil M Iyengar, Rachel Sanford, Tiffany Troso-Sandoval, Mila Gorsky, Jackie Bromberg, Pamela Drullinsky, Diana Lake, Serena Wong, Patricia DeFusco, Nicholas Lamparella, Ranja Gupta, Tasmila Tabassum, Leigh Ann Boyle, Artavazd Arumov, Tiffany A Traina. Adjuvant enzalutamide for the treatment of early-stage androgen-receptor positive, triple negative breast cancer: A feasibility study [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 P1-14-03.

Background: The addition of anti-programmed death 1/ligand 1 (anti-PD-1/L1) improves progression-free survival when combined with chemotherapy in PD-L1-positive triple-negative MBC. However, novel combination therapies are needed to improve efficacy in hormone receptor positive (HR+) MBC, or in patients with PD-L1-negative disease. Dual ICB with nivolumab (anti-PD-1) and ipilimumab (anti-CTLA-4) has not been studied in depth in MBC despite its success in other solid tumors. Furthermore, MBCs often express the androgen receptor (AR), which can be targeted therapeutically. AR blockade agents have been shown to stimulate thymic production of naïve T-cell clones. It is proposed that ICB in conjunction with AR blockade may facilitate thymopoeisis and subsequent activation of novel, tumor-reactive T-cell clones. Trial design: This is a phase II, open-label trial investigating the combination of ICB (nivolumab 240mg IV q2w; ipilimumab 1mg/kg IV q6w) and AR blockade (bicalutamide, 150mg PO daily) in MBC. Two cohorts will be studied: AR-positive TNBC [ > 1% by IHC, constituting ~50% of TNBCs]; and HR+ MBC (of which the great majority are AR-positive). Eligibility: Patients must have RECIST1.1 measurable disease, ECOG performance score 0-1, and adequate hematological and hepatic function. Subjects may have received no more than 1 prior non-curative chemotherapy. Specific aims: Subjects will be assessed for clinical benefit by iRECIST criteria and safety by CTCAE v4.0, with clinical efficacy defined as >20% improvement in week 24 clinical benefit rate, over historical control (30% per EMBRACE clinical trial). Statistical analysis will be performed by a Simon 2-stage design to minimize futility (n = 46/cohort, stage I: n = 15). As exploratory aims, thymic generation of T-cells will be measured via quantitative deep sequencing of T-cell receptors (TcR, ImmunoSEQ assay), TcR excision circles (TRECs), and flow cytometry using markers of recent thymic emigration. Present accrual: As of 7/8/2021, n=19 subjects are enrolled (4 TNBC, 15 HR+). The trial is open at Providence Cancer Institute (Portland, OR) and Memorial Sloan Kettering Cancer Center (New York, NY). Target accrual: stage I: n=15 per arm; a maximum of 138 patients (46 per cohort) may be enrolled in expansion cohorts. Contact: Dr. David Page (David.page2@providence.org) Clinicaltrials.gov#: NCT03650894 Citation Format: David B Page, Krystle L Collins, Brie Chun, Zhaoyu Sun, William L Redmond, Maritza Martel, Yaping Wu, Nicole Moxon, Staci L Mellinger, Walter J Urba, Tiffany A Traina, Ayca Gucalp. A phase II study of dual immune checkpoint blockade (ICB) plus bicalutamide to enhance thymic T-cell production and immunotherapy response in metastatic breast cancer (MBC) [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 OT1-18-04.

AimsThe most appropriate timing of exercise therapy to improve cardiorespiratory fitness (CRF) among patients initiating chemotherapy is not known. The effects of exercise therapy administered during, following, or during and following chemotherapy were examined in patients with breast cancer.Methods and resultsUsing a parallel-group randomized trial design, 158 inactive women with breast cancer initiating (neo)adjuvant chemotherapy were allocated to receive (1:1 ratio): usual care or one of three exercise regimens—concurrent (during chemotherapy only), sequential (after chemotherapy only), or concurrent and sequential (continuous) (n = 39/40 per group). Exercise consisted of treadmill walking three sessions/week, 20–50 min at 55%–100% of peak oxygen consumption (VO2peak) for ≈16 (concurrent, sequential) or ≈32 (continuous) consecutive weeks. VO2peak was evaluated at baseline (pre-treatment), immediately post-chemotherapy, and ≈16 weeks after chemotherapy. In intention-to-treat analysis, there was no difference in the primary endpoint of VO2peak change between concurrent exercise and usual care during chemotherapy vs. VO2peak change between sequential exercise and usual care after chemotherapy [overall difference, −0.88 mL O2·kg−1·min−1; 95% confidence interval (CI): −3.36, 1.59, P = 0.48]. In secondary analysis, continuous exercise, approximately equal to twice the length of the other regimens, was well-tolerated and the only strategy associated with significant improvements in VO2peak from baseline to post-intervention (1.74 mL O2·kg−1·min−1, P < 0.001).ConclusionThere was no statistical difference in CRF improvement between concurrent vs. sequential exercise therapy relative to usual care in women with primary breast cancer. The promising tolerability and CRF benefit of ≈32 weeks of continuous exercise therapy warrant further evaluation in larger trials.

Introduction: A significant proportion of aTNBC patients carry homologous recombination defects associated with platinum sensitivity. Olaparib is an approved PARP inhibitor (PARPi) for germline BRCA (gBRCA) associated early and metastatic breast cancer as well as maintenance therapy in platinum-sensitive ovarian cancer irrespective of gBRCA status. PARPi enhances immune response via cGAS/STING activation and is synergistic with anti-PD-1 blockade in preclinical models without overlapping toxicities. Here, the efficacy of maintenance olaparib (O) +/- durvalumab (D) in aTNBC patients following clinical benefit from platinum chemotherapy is investigated (NCT03167619). Methods: Eligible pts had aTNBC with investigator-assessed clinical benefit (SD, PR, CR) after a minimum of 3 q3-weekly or 6 q1-weekly cycles of platinum-based chemotherapy in the 1st or 2nd line treatment setting. Patients were randomized 1:1 to receive O 300 mg BID daily or O 300mg BID daily + D 1.5g IV q4 wks. The study was a non-comparator trial; randomization aimed to reduce bias. Tumors were evaluated by RECIST1.1 at baseline and q8 wks. Known gBRCA carriers were limited to 10. The primary endpoint was progression-free survival (PFS). Secondary endpoints were disease control rate (DCR), clinical benefit rate (CBR), and overall survival (OS). Results: From 2/4/2019-12/24/2020, 45 pts were randomized (23 pts in O arm; 22 in O+D arm). 82.2% received platinum as 1st line therapy and 82% received a platinum-doublet. As of data cutoff (6/30/2021), median follow-up of 9.8m (7.2-15.1), the median PFS was 3.95m (p= 0.0023; 95% CI 2.55-6.13) with O monotherapy. The median PFS was 6.1 mos (p= Citation Format: Sarah L. Sammons, Tira J. Tan, Young Hyunk Im, Tiffany A. Traina, Carey Anders, Ezekiel Renzulli, Sung-Bae Kim, Rebecca Dent. PD11-12 DORA: A Phase II, Multicenter, International, Non-Comparator Study of Olaparib (O) +/- Durvalumab (D) as a chemotherapy-free maintenance strategy in Platinum tReated Advanced Triple-Negative Breast Cancer (aTNBC) [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 PD11-12.

PURPOSE: Cancer survivors frequently report significant forgetfulness, but standard neuropsychological tests often fail to detect primary memory deficits. Past research has suggested survivors may misattribute forgetfulness to memory decay rather than impairments in initial encoding, but no studies have tested whether this pattern is evident in older survivors, who are more vulnerable to age-related memory difficulties. We examined whether long-term breast cancer survivors treated in older adulthood demonstrate deficits in initial encoding, as opposed to increased rates of memory decay, relative to non-cancer controls. METHODS: Three hundred twenty-eight breast cancer survivors age 60 and above, 5–15 years post-treatment, and 162 age-matched non-cancer controls completed list learning and narrative memory assessments at four time-points over 2 years. Performance on learning trials and delayed recall was analyzed at each time-point to assess group differences in memory encoding, and memory decay was assessed by analyzing changes in performance across delays. RESULTS: Univariate ANCOVAs correcting for age and education showed that survivors had worse initial encoding performance across multiple time-points, which were compensated for with multiple learning trials to produce recall performance comparable to controls. There were no significant group differences in memory decay. CONCLUSIONS: Older long-term breast cancer survivors exhibit a consistent pattern of initial encoding deficits, but memory retention was comparable to controls. Future research should consider the role of encoding deficits and age-related factors when evaluating cognitive function in older survivors. IMPLICATIONS FOR CANCER SURVIVORS: Commonly reported memory problems may stem from encoding deficits in older long-term cancer survivors.

Immunotherapy for the treatment of programmed death-ligand 1 (PD-L1) positive locally advanced or metastatic triple negative breast cancer may benefit patients with metaplastic breast cancer (MpBC). Previous study of PD-L1 in MpBC scored tumor cells (TCs), different from Food and Drug Administration-approved scoring methods. We sought to define PD-L1 expression in MpBCs and to evaluate concordance of 3 PD-L1 assays. Primary, treatment naive MpBC treated at our Center from 1998 to 2019 were identified. PD-L1 expression was assessed using SP142, E1L3n, and 73-10. We evaluated PD-L1 expression on tumor infiltrating immune cells (IC) and also in TCs. For each assay, we scored PD-L1 expression using ≥1% IC expression according to the IMpassion130 trial criteria and using combined positive score (CPS) ≥10 according to the KEYNOTE-355 trial cutoff. A total of 42 MpBCs were identified. Most MpBC had PD-L1 positivity in ≥1% IC with all 3 assays (95%, 95%, 86%) in contrast to a maximum 71% with a CPS ≥10. PD-L1 IC expression was comparable between the SP142 and 73-10 assays and was lowest with E1L3n. PD-L1 TC expression was lowest using SP142. The overall concordance for IC scoring was 88% while 62% had concordant CPS. For each assay, the results of the 2 scoring algorithms were not interchangeable. The SP142 assay showed distinct expression patterns between IC (granular, dot-like) and TC (membranous) while 73-10 and E1L3n showed membranous and/or cytoplasmic expression in both IC and TC. Most MpBC in our cohort were positive for PD-L1 indicating eligibility for anti-PD-L1/programmed death-1 immunotherapy.

Background: Trophoblast cell-surface antigen-2 (Trop-2) is highly expressed in many epithelial tumors, including triple-negative breast cancer (TNBC). Sacituzumab govitecan (SG) is an antibody-drug conjugate composed of an anti-Trop-2 antibody coupled to SN-38, an active metabolite of irinotecan, via a unique hydrolyzable linker that allows for SN-38 release intracellularly and in the tumor microenvironment (bystander effect). Preclinical studies have shown a great range of efficacy with SG in mice bearing tumors with low, moderate, and high Trop-2 expression levels. We report subgroup analyses by Trop-2 expression from ASCENT, a randomized, phase 3 confirmatory study of SG versus standard-of-care chemotherapy in patients with metastatic TNBC (mTNBC). Methods: In the global, multicenter, open-label, phase 3 ASCENT study (NCT02574455), 529 patients with mTNBC refractory to or relapsing after at least 2 prior chemotherapies were randomized 1:1 to receive SG (10 mg/kg intravenously on days 1 and 8 every 21 days) or single-agent treatment of physician’s choice (capecitabine, eribulin, vinorelbine, or gemcitabine) until disease progression or unacceptable toxicity. The primary endpoint was progression-free survival (PFS) measured by central independent review per RECIST v1.1. Secondary endpoints included objective response rate (ORR) per RECIST v1.1, duration of response, overall survival (OS), and safety. Exploratory endpoints included biomarker assessments, including Trop-2 and BRCA1/2. Trop-2 expression was assessed using a validated immunohistochemistry assay. Results: Subgroup analyses by biomarker expression including Trop-2 and BRCA1/2 were performed, and outcomes by PFS, OS, ORR, and safety results will be reported. Conclusions: These analyses will provide further insights into the relationship of Trop-2 expression and the activity of SG in previously treated patients with mTNBC. Citation Format: Sara A. Hurvitz, Sara M. Tolaney, Kevin Punie, Delphine Loirat, Mafalda Oliveira, Kevin Kalinsky, Amelia Zelnak, Philippe Aftimos, Florence Dalenc, Sagar Sardesai, Erika Hamiltion, Priyanka Sharma, Sabela Recalde, Eva Ciruelos Gil, Tiffany Traina, Joyce O'Shaughnessy, Javier Cortés, Michaela Tsai, Linda Vahdat, Véronique Diéras, Lisa Carey, Hope S. Rugo, David M. Goldenberg, Quan Hong, Martin Olivo, Loretta M. Itri, Aditya Bardia. Biomarker evaluation in the phase 3 ASCENT study of sacituzumab govitecan versus chemotherapy in patients with metastatic triple-negative 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 GS3-06.

Background: Patients (pts) with metastatic triple-negative breast cancer (mTNBC) who have brain metastases represent a poor prognosis cohort with a high unmet clinical need. Sacituzumab govitecan (SG) is an antibody-drug conjugate composed of an anti-Trop-2 antibody coupled to SN-38, an active metabolite of irinotecan, via a unique hydrolyzable linker that allows for SN-38 release intracellularly and in the tumor microenvironment (bystander effect). SN-38 can cross the blood-brain barrier and is a drug partner in central nervous system (CNS) disease regimens (PMID: 18784279; PMID: 26080460). Although antibody-based therapy raises concerns regarding CNS penetration, activity with SG has been seen in intracranial xenograft models (Brenner Neurooncol Adv 2019). In a subgroup analysis from ASCENT, the efficacy and safety of SG were evaluated in pts with stable brain metastases. Methods: In the phase 3 ASCENT study (NCT02574455), 529 pts with mTNBC refractory to or relapsing after at least 2 prior chemotherapies were randomized 1:1 to receive SG (10 mg/kg IV on days 1 and 8 every 21 days) or single-agent treatment of physician’s choice (TPC; capecitabine, eribulin, vinorelbine, or gemcitabine) until disease progression or unacceptable toxicity. Brain MRIs were required in pts with known brain metastases who were eligible if they had stable CNS disease for ≥4 wk by MRI. Per protocol, stable disease was defined as ≥2 wk from discontinuation of antiseizure medication and corticosteroid dose (≤20 mg prednisone equivalent) that was stable or decreasing for ≥2 wk before randomization. In these pts, brain MRIs were required throughout the study. The primary endpoint was progression-free survival (PFS) per independent central review (RECIST v1.1) in brain metastases-negative pts. Secondary endpoints included PFS per investigator assessment, PFS in the full population (in pts with/without brain metastases) by central review, objective response rate (ORR), overall survival (OS), and safety. Results: Overall, 61 of 529 (12%) enrolled pts had stable brain metastases at screening and were randomized to SG (n=32) or TPC (n=29). Median age was 53 y for SG and 51 y for TPC; all pts were female and had a median of 5 prior anticancer regimens. In this subset, median PFS was 2.8 mo (95% CI, 1.5-3.9) for SG vs 1.6 mo (95% CI, 1.3-2.9) for TPC by central review, and median OS was 6.8 mo (95% CI, 4.7-14.1) for SG vs 7.5 mo (95% CI, 4.7-11.1) for TPC. ORR for SG vs TPC, respectively, was 3% (1/32) vs 0% by central review, with a clinical benefit rate of 9.4% vs. 3.4%. Stable disease was achieved in 15 (47%) pts with SG vs 9 (31%) pts with TPC. In 53 pts who received at least 1 dose of treatment (SG, n=30; TPC, n=23), any-grade treatment-emergent adverse events (>20% with SG) for SG vs TPC were fatigue (63% vs 52%), diarrhea (50% vs 13%), neutropenia (43% vs 35%), nausea (43% vs 26%), decreased appetite (30% vs 17%), decreased neutrophil count (33% vs 22%), anemia (23% vs 35%), alopecia (23% vs 13%), and constipation (23% vs 22%). There were no treatment-related deaths. Two pts treated with SG are continuing study treatment for 16.2 and 6.3 mo as of the data cutoff date. Conclusions: Data interpretation in this population with poor prognosis is limited by the small sample size. In this exploratory analysis of pts with brain metastases from the phase 3 ASCENT study, SG was numerically better than TPC for tumor response and PFS but not OS. The safety profile was similar to that of the population without brain metastases for both study arms. SG is currently under clinical investigation for pts undergoing elective craniotomy for breast cancer with brain metastases or recurrent glioblastoma (NCT03995706) based on promising preclinical and intracranial clinical data. Citation Format: Véronique Diéras, Robert Weaver, Sara M. Tolaney, Aditya Bardia, Kevin Punie, Adam Brufsky, Hope S. Rugo, Kevin Kalinsky, Tiffany Traina, Leonard Klein, Delphine Loirat, Filipa Lynce, Brooke Daniel, Foluso Ademuyiwa, Sara A. Hurvitz, David M. Goldenberg, Quan Hong, Martin Olivo, Loretta M. Itri, Lisa Carey. Subgroup analysis of patients with brain metastases from the phase 3 ASCENT study of sacituzumab govitecan versus chemotherapy in metastatic triple-negative 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 PD13-07.

Introduction: U3-1402 is a novel, investigational ADC directed against HER3, which is widely expressed in breast cancer. Safety and preliminary antitumor activity of U3-1402 was previously reported in this ongoing, phase 1/2 clinical trial (NCT02980341/JapicCTI-163401). Here we report updated safety data from the dose escalation/dose finding (DE/DF) and phase 2 dose expansion parts, and we present for the first time efficacy data for patients in the expansion part with HR+/HER2− MBC with high or low levels of HER3 expression. Methods: In DE/DF, U3-1402 was administered intravenously (IV) Q2W or Q3W at doses ranging from 1.6 to 8.0 mg/kg. Patients had HER3-expressing advanced/unresectable disease refractory/intolerant to standard treatment or for which no standard treatment was available. In the expansion part, U3-1402 was administered IV Q3W to patients with HER3-high (4.8 or 6.4 mg/kg) or HER3-low (6.4 mg/kg) HR+/HER2− MBC or with HER3-high triple-negative breast cancer (TNBC; 6.4 mg/kg). Primary objectives included safety and efficacy of U3-1402; secondary objectives included correlative biomarker and pharmacokinetics analyses. Archival or pretreatment tissue obtained in the 6 months prior to U3-1402 treatment was analyzed by IHC for HER3 expression. Results: As of March 2020, all 4 expansion cohorts had completed enrollment. In the DE/DF and expansion parts combined, 172 patients received ≥1 dose of U3-1402 (114 [66%] had HR+/HER2− MBC). Median age was 56 y (range, 30-83 y); 123 (72%) and 49 (28%) patients had an ECOG PS of 0 or 1, respectively. Patients received a median of 6 (range, 1-14) prior systemic therapies. Median treatment duration of U3-1402 was 5 mo (range, 1-30 mo). 101 patients (59%) discontinued because of progressive disease, and 15 (9%) discontinued because of an AE. The most common grade ≥3 treatment-emergent AEs reported were decreased neutrophil count (43 patients [25%]), decreased platelet count (39 patients [23%]), decreased white blood cell count (28 patients [16%]), and anemia (31 patients [18%]). Nine patients (5%) experienced treatment-related interstitial lung disease according to central adjudication, including one grade 5 event. At data cutoff, 85 patients in the HR+/HER2− expansion part were evaluable for efficacy by blinded independent central review. Among 33 patients with HR+/HER2− HER3-high MBC treated with 4.8 mg/kg, 10 (30%) had a response (all partial responses [PRs]), with a clinical benefit rate (CBR; complete response + PR + stable disease for ≥6 mo) of 45% (15/33). Among 31 patients with HER3-high MBC treated with 6.4 mg/kg, 3 (10%) had a response (all PR) with a CBR of 16% (5/31). Among 21 patients with HER3-low MBC treated with 6.4 mg/kg, 6 (29%) had a response (all PRs) with a CBR of 33% (7/21). TNBC data are immature at the time of abstract data cutoff; efficacy by HR status will be provided in the presentation. Membrane HER3 expression levels were dynamic; they varied between archival and pretreatment biopsies and decreased on treatment with U3-1402. Across the doses evaluated, the U3-1402 AUC and Cmax of the total antibody, intact ADC, and released payload were approximately dose proportional, with minimal accumulation after multiple doses; the released payload Cmax was highest in cycle 1 and decreased in later cycles. Conclusions: In this heavily pretreated MBC population, U3-1402 demonstrated clinically meaningful antitumor activity in HR+/HER2− MBC with high or low levels of HER3 expression. The safety profile of U3-1402 was consistent with that previously reported, with 9% of patients discontinuing because of AEs. Clinical data pertaining to patients with TNBC and correlative analyses (including association of HER3 expression with response) will be presented. Citation Format: Ian Krop, Kan Yonemori, Shunji Takahashi, Kenichi Inoue, Takahiro Nakayama, Hiroji Iwata, Tatsuya Toyama, Yutaka Yamamoto, Masato Takahashi, Akihiko Osaki, Shigehira Saji, Yasuaki Sagara, Joyce O’Shaughnessy, Tiffany Traina, Shoichi Ohwada, Zhenhao Qi, Yang Qiu, Hiroshi Onuma, Om Sharma, Sabeen Mekan, Norikazu Masuda. Safety and efficacy results from the phase 1/2 study of U3-1402, a human epidermal growth factor receptor 3 (HER3)-directed antibody drug conjugate (ADC), in patients with HER3-expressing metastatic breast cancer (MBC) [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 PD1-09.

Summary Background Palbociclib added to endocrine therapy improves progression-free survival in hormone-receptor-positive, HER2-negative, metastatic breast cancer. The PALLAS trial aimed to investigate whether the addition of 2 years of palbociclib to adjuvant endocrine therapy improves invasive disease-free survival over endocrine therapy alone in patients with hormone-receptor-positive, HER2-negative, early-stage breast cancer. Methods PALLAS is an ongoing multicentre, open-label, randomised, phase 3 study that enrolled patients at 406 cancer centres in 21 countries worldwide with stage II–III histologically confirmed hormone-receptor-positive, HER2-negative breast cancer, within 12 months of initial diagnosis. Eligible patients were aged 18 years or older with an Eastern Cooperative Oncology Group performance score of 0 or 1. Patients were randomly assigned (1:1) in permuted blocks of random size (4 or 6), stratified by anatomic stage, previous chemotherapy, age, and geographical region, by use of central telephone-based and web-based interactive response technology, to receive either 2 years of palbociclib (125 mg orally once daily on days 1–21 of a 28-day cycle) with ongoing standard provider or patient-choice adjuvant endocrine therapy (tamoxifen or aromatase inhibitor, with or without concurrent luteinising hormone-releasing hormone agonist), or endocrine therapy alone, without masking. The primary endpoint of the study was invasive disease-free survival in the intention-to-treat population. Safety was assessed in all randomly assigned patients who started palbociclib or endocrine therapy. This report presents results from the second pre-planned interim analysis triggered on Jan 9, 2020, when 67% of the total number of expected invasive disease-free survival events had been observed. The trial is registered with ClinicalTrials.gov (NCT02513394) and EudraCT (2014-005181-30). Findings Between Sept 1, 2015, and Nov 30, 2018, 5760 patients were randomly assigned to receive palbociclib plus endocrine therapy (n=2883) or endocrine therapy alone (n=2877). At the time of the planned second interim analysis, at a median follow-up of 23·7 months (IQR 16·9–29·2), 170 of 2883 patients assigned to palbociclib plus endocrine therapy and 181 of 2877 assigned to endocrine therapy alone had invasive disease-free survival events. 3-year invasive disease-free survival was 88·2% (95% CI 85·2–90·6) for palbociclib plus endocrine therapy and 88·5% (85·8–90·7) for endocrine therapy alone (hazard ratio 0·93 [95% CI 0·76–1·15]; log-rank p=0·51). As the test statistic comparing invasive disease-free survival between groups crossed the prespecified futility boundary, the independent data monitoring committee recommended discontinuation of palbociclib in patients still receiving palbociclib and endocrine therapy. The most common grade 3–4 adverse events were neutropenia (1742 [61·3%] of 2840 patients on palbociclib and endocrine therapy vs 11 [0·3%] of 2903 on endocrine therapy alone), leucopenia (857 [30·2%] vs three [0·1%]), and fatigue (60 [2·1%] vs ten [0·3%]). Serious adverse events occurred in 351 (12·4%) of 2840 patients on palbociclib plus endocrine therapy versus 220 (7·6%) of 2903 patients on endocrine therapy alone. There were no treatment-related deaths. Interpretation At the planned second interim analysis, addition of 2 years of adjuvant palbociclib to adjuvant endocrine therapy did not improve invasive disease-free survival compared with adjuvant endocrine therapy alone. On the basis of these findings, this regimen cannot be recommended in the adjuvant setting. Long-term follow-up of the PALLAS population and correlative studies are ongoing. Funding Pfizer.

Purpose: To determine whether the androgen receptor (AR) inhibitor, enzalutamide, improves effectiveness of endocrine therapy (ET) in hormone receptor–positive (HR+) breast cancer. Patients and Methods: In this phase II trial, patients with HR+/HER2 normal advanced/metastatic breast cancer were randomized 1:1 to exemestane 25 mg with placebo or exemestane 50 mg with enzalutamide 160 mg daily (NCT02007512). Two parallel cohorts enrolled patients with 0 (cohort 1) or 1 (cohort 2) prior ET for advanced disease. Progression-free survival (PFS) was the primary endpoint in the intent-to-treat (ITT) population of each cohort. Biomarkers were evaluated in an exploratory analysis. Results: Overall, 247 patients were randomized (cohort 1, n = 127 and cohort 2, n = 120). PFS was not improved in either cohort of the ITT population [HR, 0.82 (95% confidence interval (CI), 0.54–1.26); P = 0.3631 for cohort 1 and HR, 1.02 (95% CI, 0.66–1.59); P = 0.9212 for cohort 2]. In cohort 1, high levels of AR mRNA were associated with greater benefit of enzalutamide (Pinteraction = 0.0048). This effect was particularly apparent in patients with both high levels of AR mRNA and low levels of ESR1 mRNA [HR, 0.24 (95% CI, 0.10–0.60); P = 0.0011]. The most common any grade adverse events in the enzalutamide arms were nausea (39%) in cohort 1 and fatigue (37%) in cohort 2. Conclusions: Enzalutamide with exemestane was well tolerated. While PFS was not improved by the addition of enzalutamide to exemestane in an unselected population, ET-naïve patients with high AR mRNA levels, particularly in combination with low ESR1 mRNA levels, may benefit from enzalutamide with exemestane.

Chemotherapy with or without immunotherapy remains the mainstay of treatment for triple-negative breast cancer (TNBC). A subset of TNBCs express the androgen receptor (AR), representing a potential new therapeutic target. This study assessed the feasibility of adjuvant enzalutamide, an AR antagonist, in early-stage, AR-positive (AR +) TNBC.This study was a single-arm, open-label, multicenter trial in which patients with stage I-III, AR ≥ 1% TNBC who had completed standard-of-care therapy were treated with enzalutamide 160 mg/day orally for 1 year. The primary objective of this study was to evaluate the feasibility of 1 year of adjuvant enzalutamide, defined as the treatment discontinuation rate of enzalutamide due to toxicity, withdrawal of consent, or other events related to tolerability. Secondary endpoints included disease-free survival (DFS), overall survival (OS), safety, and genomic features of recurrent tumors.Fifty patients were enrolled in this study. Thirty-five patients completed 1 year of therapy, thereby meeting the prespecified trial endpoint for feasibility. Thirty-two patients elected to continue with an optional second year of treatment. Grade ≥ 3 treatment-related adverse events were uncommon. The 1-year, 2-year, and 3-year DFS were 94%, 92% , and 80%, respectively. Median OS has not been reached.This clinical trial demonstrates that adjuvant enzalutamide is a feasible and well-tolerated regimen in patients with an early-stage AR + TNBC. Randomized trials in the metastatic setting may inform patient selection through biomarker development; longer follow-up is needed to determine the effect of anti-androgens on DFS and OS in this patient population.

PURPOSE: Rash develops in approximately 50% of patients receiving alpelisib for breast cancer, often requiring dose modifications. Here, we describe the clinicopathologic, laboratory, and management characteristics of alpelisib-related dermatologic adverse events (dAEs). METHODS: A single center retrospective analysis was conducted. Data were abstracted from electronic medical records. RESULTS: A total of 102 patients (mean age 56 years, range 27-83) receiving alpelisib most frequently in combination with endocrine therapy (79, 77.5%) were included. We identified 41 (40.2%) patients with all-grade rash distributed primarily along the trunk (78%) and extremities (70%) that developed approximately within two weeks of treatment initiation (mean 12.8 ± 1.5 days) and lasted one-week (mean duration 7.1 ± 0.8 days). Of 29 patients with documented morphology of alpelisib-related dAEs, 26 (89.7%) had maculopapular rash. Histology showed perivascular and interface lymphocytic dermatitis. All-grade rash correlated with an increase in serum eosinophils from 2.7% to 4.4%, p

Background Endocrine therapies and CDK4/6 inhibitors have dramatically improved outcomes for patients with hormone receptor-positive (HR+) metastatic breast cancer (MBC). To help inform treatment decisions among healthcare providers (HCPs) caring for patients with MBC, we have developed and regularly updated an online treatment decision support tool that provides recommendations from multiple breast cancer experts for specifically defined patient scenarios. Here we report data for HR+/HER2- MBC cases entered into the tool since 2016, capturing self-reported practice trends from HCPs compared with matched treatment recommendations from experts. Methods For the most recent MBC treatment tool (published October 2018), 5 breast cancer experts provided treatment consultation for 549 unique MBC case scenarios based on a simplified set of variables: disease phenotype, previous systemic therapy, visceral crisis (yes/no), rate of disease progression, and the presence or absence of germline BRCA1/2 mutations. HCPs used selection menus to enter patient and disease factors based on these variables along with their intended treatment plan. When completed, the experts’ treatment recommendations for that specific patient case were shown to the HCPs at which time they were asked to indicate if the expert recommendations changed their planned treatment. Results From October 2018 through June 2019, 603 HCPs entered 1127 patient case scenarios, including 581 HR+/HER2- MBC cases, in the most recent online tool. A comparison of expert and HCP treatment choices for select HR+/HER2- MBC case scenarios from the October 2016 and October 2018 tool is shown in the Table. In the setting of HR+/HER2- MBC, among those HCPs whose planned treatment differed from the consensus expert recommendation, 55% indicated that they would change their original choice of treatment. Conclusions CDK4/6 inhibitors have had a large impact on expert treatment recommendations for patients with HR+/HER2- MBC. However, data from this online treatment decision support tool suggest ongoing differences in practice between experts and community HCPs in this setting. For many cases entered into the tool, the practice of the majority of HCPs differed from expert consensus (Table). Consensus expert recommendations in this online tool changed the intended treatment plan of many using it and, therefore, can help optimize the care of patients with MBC. A detailed analysis of overall community practice trends for HR+/HER2- MBC along with a comparison of expert and HCP practice for different case scenarios will be presented. HR+/HER2- MBC Case Scenarios (no visceral crisis)Expert Consensus Recommendation (%)Expert Consensus Recommendation (%)HCP Practice Matched Expert Consensus Recommendation, % (n)HCP Practice Matched Expert Consensus Recommendation, % (n)2016201820162018de novoCDK4/6i + AI (100)CDK4/6i + AI (100)23 (111)32 (188)Previous (neo)adjuvant AICDK4/6i + FULV (92)CDK4/6i + FULV (90)22 (54)17 (77)Previous CDK4/6i + AIFULV (82)FULV ± EVE (92)0 (14)18 (40)Previous AI and CDK4/6i + FulvEVE + EXE (87)EVE + EXE (73)63 (19)28 (18) Citation Format: Timothy Quill, Sara Hurvitz, Kathy D. Miller, Ruth O'Regan, Tiffany A. Traina, Rachael Andrie, Kevin L. Obholz, Mohammad Jahanzeb. Treatment patterns for metastatic hormone receptor-positive breast cancer: Comparing expert and community practice [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P4-14-07.

BACKGROUND: A subset of TNBC expresses a luminal signature and demonstrates AR-dependence. Enzalutamide (ENZA), an AR-antagonist, has activity with metastatic AR+ TNBC, with a clinical benefit rate of 33% (Traina et al, JCO 2018). We recently demonstrated that one year (y) of adjuvant ENZA is feasible in early stage, AR+ TNBC, with no new safety signals observed (Traina ASCO 2019). Fatigue was the most common, treatment (tx)-related, adverse event of any grade according to investigator assessment (24%). Here we report per-protocol planned secondary analyses of PROs during one year of ENZA including quality of life (QoL), fatigue, and self-reported physical activity (NCT02750358). METHODS: Eligible patients have Stage I-III, ER/PR RESULTS: Between 5/2016 and 6/2018, 50 patients were enrolled. As of 6/27/19, 34 patients completed 1y of ENZA; 15 patients are off tx: recurrence (3), toxicity (5), nonadherence (4), and consent withdrawal (3). Patients evaluable for PRO (N): baseline (50), 12 weeks (43) and 52 weeks (34). Median scores on FACT-B and fatigue scales remained stable over the course of adjuvant ENZA in the 1st year of therapy (Table). Self-reported exercise increased during this period. Table. Median scores (range) for PROs during 1 year of adjuvant ENZATime PointBaselineWeek 12Week 52FACT-G88.0 (53.5-105.0)82.0 (36.4-105.0)89.5 (58.0-105.0)Breast Cancer Subscale28.5 (15.6-39.0)29.0 (9.0-40.0)29.0 (19.0-40.0)Total118.0 (77.0-141.0)111.0 (45.4-145.0)121.0 (83.0-145.0)FACT-B trial outcome index73.0 (43.0-92.0)73.0 (25.7-96.0)76.9 (51.0-96.0)FACIT43.0 (17.0-52.0)39.0 (10.0-52.0)43.0 (11.0-52.0)Total Exercise (min/week)120 (0-1260)152 (0-3120)180 (0-2580) CONCLUSIONS: Patient reported outcomes of health related QOL remain stable when ENZA is administered for 1 year in the adjuvant setting. Self-reported time spent engaged in physical exercise increased numerically during 1y of therapy. During presentation, additional analyses will be reported including QOL at additional time points, relationship of FACT-B score with FACIT fatigue score and exercise, and QOL changes in relation to relative dose intensity of ENZA, toxicity and off study reason. Citation Format: Tiffany A Traina, Lee W Jones, Victoria Blinder, Jessica Scott, Leigh Ann Boyle, Artavazd Arumov, Tina Alano, Sujata Patil, Patricia DeFusco, Nicholas Lamparella, Mark Robson, Ayca Gucalp. Patient-reported outcomes (PROs) during one year of adjuvant enzalutamide for the treatment of early stage androgen receptor positive (AR+) triple negative breast cancer [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P5-12-09.

Background: Male breast cancer is rare, with approximately 2,600 cases diagnosed annually in the United States. Data are scant regarding the genomics and pathophysiology of male breast cancer, especially in the metastatic setting, requiring most treatment recommendations in male breast cancer to be made by inference from breast cancer in women. Methods: We performed prospective genomic profiling of primary and metastatic tumor samples from men with breast cancer treated at Memorial Sloan Kettering Cancer Center using the MSK-IMPACT targeted-DNA-sequencing panel for somatic mutations. Comprehensive demographic, clinical, and pathologic data were collected on all included patients. Statistics are descriptive. Results: Genomic sequencing was performed on 45 samples from 41 men (31 primary samples and 14 from metastatic sites). Median age at time of sample collection was 61 years, with a range of 27-92 years. Thirty-seven (90.2%) men had ER+/HER2- breast cancer, 3 (7.3%) had ER+/HER2+ breast cancer and 1 (2.4%) had triple negative disease. Thirty-nine (95.1%) had ductal carcinoma, and no cases of lobular carcinoma were identified. Forty patients underwent germline testing, and 12 (30%) were found to have pathogenic germline mutations (6 BRCA2 mutations, 2 BRCA1 mutations [one of whom had a concurrent CHEK2 mutation], and one mutation each in PALB2, MUTYH, and MSH6). Overall, the pattern of genomic alterations in male breast cancer was similar that in women. Twelve (29.3%) patients had PIK3CA mutations, 9 (22%) had GATA3 mutations, 3 (7.3%) had TP53 mutations, 3 (7.3%) had ARID1A mutations, 3 (7.3%) had KMT2C mutations, 2 (4.9%) had FOX1A mutations, 2 (4.9%) had RB1 mutations, and 2 (4.9%) had TERT promoter hotspot mutations. Eleven (26.8%) patients had CCND1 amplification, 8 (19.5%) had MYC amplification, 6 (14.6%) had FGFR1 amplification, and 5 (12.2%) had MDM2 amplification. All other findings were present in ≤ 1 patient. All included patients had normal mutational burden, and all samples were microsatellite stable. PIK3CA mutations occurred in 33% of primary samples vs. 15% of metastatic samples, CCND1 amplification occurred in 23% of primary samples vs. 38% of metastatic samples, and TERT hotspot promoter mutations were found only in metastatic samples. Of note, we observed a single ESR1 D538G mutation in the metastatic sample of a patient with significant prior exposure to aromatase inhibitors in the adjuvant and metastatic settings. We further found concurrent ERBB2 mutation and amplification in the post-treatment metastatic samples of an ER+/HER2- patient, who was treated with neratinib for 14 weeks with clinical response. Lastly, we report a heavily pretreated patient with metastatic secretory breast carcinoma who was found to have an ETV6-NTRK3 fusion gene. This patient was treated with a first-generation TRK inhibitor and continues to exhibit an ongoing clinical response at 8.6 months. Conclusions: Based on our data, the overall genomic landscape of male breast cancer appears comparable to that of breast cancer in women, as has been previously reported. However, despite the small number of metastatic cases examined, several previously unreported and treatment-informing signatures were discovered, especially in those patients with less common male breast cancer variants. Further study is warranted to confirm these findings in a larger cohort. Citation Format: Joshua Z Drago, Cristian Serna-Tamayo, Carlos H Dos Anjos, David N Brown, Shanu Modi, Komal Jhaveri, David B Solit, Tiffany A Traina, Sarat Chandarlapaty, Jorge S Reis-Filho, Mark E Robson, Ayca Gucalp, Pedram Razavi. Genomic profiling of primary and metastatic breast cancer in men [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P4-17-01.

PURPOSE The PALLAS study investigated whether the addition of palbociclib, an oral CDK4/6 inhibitor, to adjuvant endocrine therapy (ET) improves invasive disease-free survival (iDFS) in early hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2–) breast cancer. In this analysis, we evaluated palbociclib exposure and discontinuation in PALLAS. METHODS Patients with stage II-III HR+, HER2– disease were randomly assigned to 2 years of palbociclib with adjuvant ET versus ET alone. The primary objective was to compare iDFS between arms. Continuous monitoring of toxicity, dose modifications, and early discontinuation was performed. Association of baseline covariates with time to palbociclib reduction and discontinuation was analyzed with multivariable competing risk models. Landmark and inverse probability weighted per-protocol analyses were performed to assess the impact of drug persistence and exposure on iDFS. RESULTS Of the 5,743 patient analysis population (2,840 initiating palbociclib), 1,199 (42.2%) stopped palbociclib before 2 years, the majority (772, 27.2%) for adverse effects, most commonly neutropenia and fatigue. Discontinuation of ET did not differ between arms. Discontinuations for non–protocol-defined reasons were greater in the first 3 months of palbociclib, and in the first calendar year of accrual, and declined over time. No significant relationship was seen between longer palbociclib duration or ≥ 70% exposure intensity and improved iDFS. In the weighted per-protocol analysis, no improvement in iDFS was observed in patients receiving palbociclib versus not (hazard ratio 0.89; 95% CI, 0.72 to 1.11). CONCLUSION Despite observed rates of discontinuation in PALLAS, analyses suggest that the lack of significant iDFS difference between arms was not directly related to inadequate palbociclib exposure. However, the discontinuation rate illustrates the challenge of introducing novel adjuvant treatments, and the need for interventions to improve persistence with oral cancer therapies.

BackgroundIt has previously been shown that immune checkpoint blockade (ICB) with anti-programmed death 1/ligand 1 (anti-PD-1/L1) improves survival when combined with chemotherapy in PD-L1-positive first-line triple-negative metastatic breast cancer (MBC). Given the lower efficacy of ICB in hormone receptor positive (HR+) or PD-L1-negative disease, and in later lines of therapy, novel combinations are necessary. Dual ICB with nivolumab (anti-PD-1) and ipilimumab (anti-CTLA-4) has shown success in other solid tumors but has not been extensively studied in MBC. Furthermore, MBCs often express the androgen receptor (AR), which can be targeted to modulate immune response. AR blockade may stimulate thymic production of naïve T-cell clones by modulating the Notch pathway,1 whereas ICB can amplify the immune activity of recent thymic emigrants by blocking PD-1-mediated peripheral tolerance.2MethodsThis is an open-label, Simon 2-stage phase II trial investigating the dual ICB (nivolumab 240mg IV q2w; ipilimumab 1mg/kg IV q6w) and AR blockade (bicalutamide, 150mg PO daily) in MBC. Two cohorts will be studied: AR-positive TNBC [ > 1% by IHC, constituting ~50% of TNBCs]; and HR+ MBC (of which the great majority are AR-positive). Eligible patients must have RECIST1.1 measurable disease, Eastern Cooperative Oncology Group performance score 0 or 1, adequate hematological/hepatic function, and received no more than 1 prior course of non-curative chemotherapy. Target accrual is n=15 per arm (stage I), with a maximum of 46 patients per cohort. Current cohort accrual n=15 HR+ and n=5 TNBC. The primary endpoint is week 24 clinical benefit by iRECIST criteria, with success defined as >20% improvement over historical control (30% per EMBRACE clinical trial).3 Safety will be evaluated by CTCAE v4.0. Biomarkers of recent thymic activation will be evaluated via quantitative deep sequencing of T-cell receptors (TcR, ImmunoSEQ assay), TcR excision circles (TRECs), and flow cytometry using markers for recent thymic emigration (CD3+CD45RA+CD45RO-CD31+)Trial RegistrationNCT03650894. The trial is open at Providence Cancer Institute (Portland, OR) and Memorial Sloan Kettering Cancer Center (New York, NY).ReferencesVelardi E, Tsai JJ, Holland AM, et al. Sex steroid blockade enhances thympoesis modulating notch signaling. J Exp Med 2014;211(12):2341–49.Thangavelu G, Parkman JC, Ewen CL, et al. Programmed death-1 is required for systemic self-tolerance in newlygenerated T cells during the establishment of immune homeostasis. Journal of autoimmunity 2011;36(3–4):301–12.Kaufman PA, Awada A, Twevles C, et al. Phase III open-label randomized study of eribulin mesylate versus capecitabine in patients with locally advanced or metastatic breast cancer previously treated with an anthracycline and a taxane. J Clin Oncol 2015;33(6):594–601.Ethics ApprovalThis study was approved by the IRB department and Providence Portland Medical Center, Clinical Trials Department for study NCT03650894.ConsentWritten, informed consent is obtained from each participant.

Purpose: While chemotherapy remains the standard treatment for triple-negative breast cancer (TNBC), identifying and managing chemoresistant tumors has proven elusive. We sought to discover hallmarks and therapeutically actionable features of refractory TNBC through molecular analysis of primary chemoresistant TNBC specimens. Experimental Design: We performed transcriptional profiling of tumors from a phase II clinical trial of platinum chemotherapy for advanced TNBC (TBCRC-009), revealing a gene expression signature that identified de novo chemorefractory tumors. We then employed pharmacogenomic data mining, proteomic and other molecular studies to define the therapeutic vulnerabilities of these tumors. Results: We reveal the RAS-GTPase-activating protein (RAS-GAP) RASAL2 as an upregulated factor that mediates chemotherapy resistance but also an exquisite collateral sensitivity to combination MAP kinase kinase (MEK1/2) and EGFR inhibitors in TNBC. Mechanistically, RASAL2 GAP activity is required to confer kinase inhibitor sensitivity, as RASAL2-high TNBCs sustain basal RAS activity through suppression of negative feedback regulators SPRY1/2, together with EGFR upregulation. Consequently, RASAL2 expression results in failed feedback compensation upon co-inhibition of MEK1/2 and EGFR that induces synergistic apoptosis in vitro and in vivo. In patients with TNBC, high RASAL2 levels predict clinical chemotherapy response and long-term outcomes, and are associated via direct transcriptional regulation with activated oncogenic Yes-Associated Protein (YAP). Accordingly, chemorefractory patient-derived TNBC models exhibit YAP activation, high RASAL2 expression, and tumor regression in response to MEK/EGFR inhibitor combinations despite well-tolerated intermittent dosing. Conclusions: These findings identify RASAL2 as a mediator of TNBC chemoresistance that rewires MAPK feedback and cross-talk to confer profound collateral sensitivity to combination MEK1/2 and EGFR inhibitors.

Background: The pivotal phase III ASCENT trial demonstrated improved survival outcomes associated with sacituzumab govitecan (SG), an anti-trophoblast cell-surface antigen 2 (anti-Trop-2) antibody-drug conjugate linked with the topoisomerase-inhibitor SN-38, over single-agent chemotherapy treatment of physician's choice (TPC) in previously treated metastatic triple-negative breast cancer (mTNBC). This prespecified, exploratory biomarker analysis from the ASCENT trial evaluates the association between tumor Trop-2 expression and germline BRCA1/2 mutation status with clinical outcomes. Patients and methods: Patients with mTNBC refractory to or progressing after two or more prior chemotherapies, with one or more in the metastatic setting, were randomized to receive SG (10 mg/kg intravenously days 1 and 8, every 21 days) or TPC (capecitabine, eribulin, vinorelbine, or gemcitabine) until disease progression/unacceptable toxicity. Biopsy or surgical specimens were collected at study entry to determine Trop-2 expression level using a validated immunohistochemistry assay and histochemical scoring. Germline BRCA1/2 mutation status was collected at baseline. Results: Of 468 assessable patients, 290 had Trop-2 expression data [64% (n = 151 SG) versus 60% (n = 139 TPC)] and 292 had known BRCA1/2 mutation status [63% (n = 149 SG) versus 61% (n = 143 TPC)]. Median progression-free survival in SG- versus TPC-treated patients was 6.9, 5.6, and 2.7 months versus 2.5, 2.2, and 1.6 months for high, medium, and low Trop-2 expression, respectively. Median overall survival (14.2, 14.9, and 9.3 months versus 6.9, 6.9, and 7.6 months) and objective response rates (44%, 38%, and 22% versus 1%, 11%, and 6%) were numerically higher with SG versus TPC in patients with high, medium, and low Trop-2 expression, respectively. Efficacy outcomes were numerically higher with SG versus TPC in patients with and without germline BRCA1/2 mutations. Conclusions: SG benefits patients with previously treated mTNBC expressing high/medium Trop-2 compared with standard-of-care chemotherapy and regardless of germline BRCA1/2 mutation status. The small number of patients with low Trop-2 expression precludes definitive conclusions on the benefit of SG in this subgroup., SCOPUS: ar.j, info:eu-repo/semantics/published

Purpose/Objective(s) We hypothesize that there is an oligoprogressive state in metastatic cancer, in which disease control can be improved with local therapy to progressive lesions only. This study therefore evaluated the impact of stereotactic body radiotherapy (SBRT) to sites of oligoprogression in patients with metastatic non-small-cell lung cancer (NSCLC) and breast cancer with 1-5 progressive lesions. Materials/Methods We enrolled patients with metastatic NSCLC or breast cancer who received ≥ 1 line of systemic therapy and had oligoprogressive lesions amenable to SBRT. There was no upper limit of non-progressive lesions. Oligoprogression was defined as Response Evaluation or Positron Emission Tomography Response Criteria in Solid Tumors documented progression ≤ 5 individual lesions. Stratification factors included number of progressive sites (1 vs. 2-5), prior systemic therapy (immunotherapy vs. other), primary tumor (NSCLC vs. breast), and tumor marker status (driver mutation and hormone receptor status). Patients were randomized 1:1 between SBRT to all progressive sites plus palliative standard of care (SOC) vs. palliative SOC only. Systemic therapy was per physician's discretion. The primary endpoint was progression-free survival (PFS). We used a randomized phase II design with a one-sided alpha of 0.05 and a power of 0.80, yielding a target accrual of 160 patients. PFS was compared using one-sided stratified log-rank test. One interim analysis was planned. Results From January 2019 to May 2021, 102 patients were randomized - 58 NSCLC (30 in the SBRT arm) and 44 breast (22 in each arm). Median age was 67. Most patients (75%) had > 1 site of oligoprogression and 47% had > 5 total metastatic lesions. Fifty-five (54%) patients received immunotherapy. The majority of NSCLC (86%) did not harbor an actionable driver mutation and 32% of breast cancer were triple negative. Baseline factors were balanced between arms. At a median follow-up of 51 weeks, 71 patients progressed and 30 died. Median PFS was 22 weeks in the SBRT arm vs. 10 weeks in the palliative SOC arm (p=0.005). This was driven entirely by the PFS benefit from SBRT in the NSCLC patients (44 weeks with SBRT vs. 9 weeks with SOC; p=0.004). No difference in median PFS was seen in the breast cohort (18 weeks with SBRT vs. 17 weeks with SOC; p=0.5). In multivariable Cox model inclusive of stratification factors, age, sex, lines of systemic therapy, and change of systemic therapy, the PFS benefit of SBRT remained substantial in the NSCLC cohort (Hazard Ratio: 0.38; 95% CI: 0.18-77; p=0.007). Grade ≥2 adverse events occurred in 8 patients in the SBRT arm, including 1 grade 3 pneumonitis. Conclusion Inthis pre-planned interim analysis of the first and largest randomized trial of radiotherapy for oligoprogressive metastatic NSCLC and breast cancer, we demonstrated the benefit of SBRT to sites of oligoprogression on overall PFS, meeting the primary endpoint. The mechanism of the differential benefits between NSCLC and breast cohorts merits further evaluation.

12022 Background: Late alopecia is defined as incomplete hair regrowth > 6 months following cytotoxic chemotherapy or from initiation of endocrine therapy. It has been reported in up to 25-30% of cancer survivors and is associated with decreased quality of life and reduced dose intensity of cancer therapies. Minoxidil is an aminopyridine potassium channel opener, resulting in vasodilation and premature entry of resting hair follicles into the anagen (growth) phase and increase in hair follicle size. This study aims to assess clinical outcomes and adverse events of oral minoxidil for the treatment of cancer therapy-related late alopecia. Methods: We retrospectively assessed all women with late alopecia treated with oral minoxidil (1.25 mg daily) evaluated at an oncodermatology referral program between 1/2018-5/2021. Outcomes were assessed by standardized photography (4 views) and trichoscopy (HairMetrix, Canfield Scientific, Inc.). Trichoscopy recorded hair density (hair count/cm2) and hair thickness (shaft diameter) at uniform frontal and occipital target areas (12 and 36 cm midline from the glabella, respectively). Adverse events were recorded and graded using CTCAE v5.0. Descriptive statistics were used to summarize the patient demographics and clinical characteristics. Changes in trichoscopy measurements from baseline to follow-up were estimated using paired t-tests. Results: Two hundred and sixteen patients (mean age 57.8±13.7) were included for analysis. Thirty-one (14%) received chemotherapy alone, 65 (30%) endocrine monotherapy, and 120 (56%) chemotherapy followed by endocrine therapy. The majority of patients (n = 170, 79.1%) had a history of breast cancer. Standardized photography assessments (n = 119) after a median of 105 days (IQR = 70) on oral minoxidil revealed clinical improvement in 88 (74%). Trichoscopy assessments (n = 42) after a median of 91 days (IQR = 126) demonstrated increased frontal hair density (124.2 vs 153.2 hairs/cm2, p = 0.008) and occipital hair density (100.3 vs 123.5 hairs/cm2, p = 0.004). There was no statistically significant difference in average frontal or occipital hair thickness (69.3 vs 67.3 μm, p = 0.22, and 70.3 vs 69.9 μm, p = 0.84, respectively). No patients reported discontinuation of oral minoxidil due to adverse effects. Conclusions: Oral minoxidil may benefit both frontal and occipital late alopecia in cancer survivors treated with cytotoxic and/or endocrine therapy. This regimen was well tolerated by patients. Prospective, controlled studies are needed to confirm these observations.

Androgen receptor (AR) inhibitor therapy is a developing treatment for AR-positive breast cancer (BC) with ongoing clinical trials. AR splice variant-7 (AR-V7) is a truncated variant of AR that leads to AR inhibitor therapy resistance in prostate cancer; recent studies have identified AR-V7 in BC and theorized that AR-V7 can have a similar impact. This study assessed the prevalence and clinicopathologic features associated with AR-V7 in a large BC cohort. BC samples were evaluated by MSK-Fusion targeted RNAseq for AR-V7 detection and MSK-IMPACT targeted DNAseq, including triple-negative tumors with no driver alteration and estrogen receptor-positive/ESR1 wildtype tumors progressing on therapy. Among 196 primary and metastatic/recurrent cases (196 RNAseq, 194DNAseq), 9.7% (19/196) were AR-V7 positive and 90.3% (177/196) AR-V7 negative. All AR-V7 positive BC were AR-positive by immunohistochemistry (19/19). The prevalence of AR-V7 by receptor subtype (N = 189) was: 18% (12/67) in ER-/PgR-/HER2-negative BC, 3.7% (4/109) in ER-positive/HER2-negative BC, and 15.4% (2/13) in HER2-positive BC; AR-V7 was detected in one ER-positive/HER2-unknown BC. Apocrine morphology was observed in 42.1% (8/19) of AR-V7 positive BC and 3.4% (6/177) AR-V7 negative BC (P 0.00001). Notably, AR-V7 was detected in 2 primary BC and 7 metastatic/recurrent BC patients with no prior endocrine therapy. We conclude that positive AR IHC and apocrine morphology are pathologic features that may indicate testing for AR-V7 is warranted in both primary and metastatic BC in the appropriate clinical context. The study findings further encourage the assessment of AR-V7 as a predictive biomarker for AR antagonist benefit in ongoing clinical BC trials.

Background Locally advanced and metastatic breast cancer remains a challenge to treat. With emerging study results, it is important to interpret the available clinical data and apply the evidence offering the most effective treatment to the right patient. Poly(ADP Ribose) Polymerase (PARP) inhibitors are a new class of drug and their role in the treatment of locally advanced and metastatic breast cancer is being established. Objectives To determine the efficacy, safety profile, and potential harms of Poly(ADP-Ribose) Polymerase (PARP) inhibitors in the treatment of patients with locally advanced or metastatic breast cancer. The primary outcome of interest was overall survival; secondary outcomes included progression-free survival, tumour response rate, quality of life, and adverse events. Search methods On 8 June 2020, we searched the Cochrane Breast Cancer Group Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE via OvidSP, Embase via OvidSP, World Health Organization International Clinical Trials Registry Platform (WHO ICTRP) search portal and ClinicalTrials.gov. We also searched proceedings from the major oncology conferences as well as scanned reference lists from eligible publications and contacted corresponding authors of trials for further information, where needed. Selection criteria We included randomised controlled trials on participants with locally advanced or metastatic breast cancer comparing 1) chemotherapy in combination with PARP inhibitors, compared to the same chemotherapy without PARP inhibitors or 2) treatment with PARP inhibitors, compared to treatment with other chemotherapy. We included studies that reported on our primary outcome of overall survival and secondary outcomes including progression-free survival, tumour response rate, quality of life, and adverse events. Data collection and analysis We used standard methodological procedures defined by Cochrane. Summary statistics for the endpoints used hazard ratios (HR) with 95% confidence intervals (CI) for overall survival and progression-free survival, and odds ratios (OR) for response rate (RR) and toxicity. Main results We identified 49 articles for qualitative synthesis, describing five randomised controlled trials that were included in the quantitative synthesis (meta-analysis). A sixth trial was assessed as eligible but had ended prematurely and no data were available for inclusion in our meta-analysis. Risk of bias was predominately low to unclear across all studies except in regards to performance bias (3/5 high risk) and detection bias for the outcomes of quality of life (2/2 high risk) and reporting of adverse events (3/5 high risk). High-certainty evidence shows there may be a small advantage in overall survival (HR 0.87, 95% CI 0.76 to 1.00; 4 studies; 1435 patients). High-certainty evidence shows that PARP inhibitors offer an improvement in PFS in locally advanced/metastatic HER2-negative, BRCA germline mutated breast cancer patients (HR 0.63, 95% CI 0.56 to 0.71; 5 studies; 1474 patients). There was no statistical heterogeneity for these outcomes. Subgroup analyses for PFS outcomes based on trial level data were performed for triple-negative breast cancer, hormone-positive and/or HER2-positive breast cancer, BRCA1 and BRCA2 germline mutations, and patients who had received prior chemotherapy for advanced breast cancer or not. The subgroup analyses showed a persistent PFS benefit regardless of the subgroup chosen. Pooled analysis shows PARP inhibitors likely result in a moderate improvement in tumour response rate compared to other treatment arms (66.9% vs 48.9%; RR 1.39, 95% CI 1.24 to 1.54; 5 studies; 1185 participants; moderate-certainty evidence). The most common adverse events reported across all five studies included neutropenia, anaemia and fatigue. Grade 3 or higher adverse events probably occur no less frequently in patients receiving PARP inhibitors (59.4% for PARP arm versus 64.5% for non-PARP arm, RR 0.98, 95% CI 0.91 to 1.04; 5 studies; 1443 participants; moderate-certainty evidence). Only two studies reported quality of life outcomes so this was not amenable to meta-analysis. However, both studies that did assess quality of life showed PARP inhibitors were superior compared to physician's choice of chemotherapy in terms of participant-reported outcomes. Authors' conclusions In people with locally advanced or metastatic HER2-negative, BRCA germline mutated breast cancer, PARP inhibitors offer an improvement in progression-free survival, and likely improve overall survival and tumour response rates. This systematic review provides evidence supporting the use of PARP inhibitors as part of the therapeutic strategy for breast cancer patients in this subgroup. The toxicity profile for PARP inhibitors is probably no worse than chemotherapy but more information is required regarding quality of life outcomes, highlighting the importance of collecting such data in future studies. Future studies should also be powered to detect clinically important differences in overall survival and could focus on the role of PARP inhibitors in other relevant breast cancer populations, including HER2-positive, BRCA-negative/homologous recombination repair-deficient and Programmed Death-Ligand 1 (PDL1) positive.