Timing of exercise therapy when initiating adjuvant chemotherapy for breast cancer: a randomized trial

AIMS

The 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 RESULTS

Using 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).

CONCLUSION

There 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.

Adjuvant enzalutamide for the treatment of early-stage androgen-receptor positive, triple-negative breast cancer: a feasibility study

PURPOSE

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.

METHODS

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.

RESULTS

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.

CONCLUSION

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.

A phase 1b/2 study of the BET inhibitor ZEN-3694 in combination with talazoparib for treatment of patients with TNBC without gBRCA1/2 mutations

1023

Background: Metastatic triple negative breast cancer (mTNBC) is an aggressive and heterogeneous cancer with limited therapeutic options. PARP inhibitors (PARPi), approved to treat patients with HER2- breast cancer with a germline BRCA1/2 (gBRCA1/2) mutation, have not shown efficacy in homologous recombination repair (HRR) proficient tumors. In pre-clinical models, the BET inhibitor (BETi) ZEN-3694 sensitizes wild-type (WT) BRCA1/2 tumors to PARPi through downregulation of HRR gene expression, providing a rationale for combination therapy. We previously reported results from the Ph 1b portion of the trial evaluating the combination of ZEN-3694 plus talazoparib, in TNBC patients without gBRCA1/2 mutations; here we present results from the completed Ph 1b/2 study. Methods: A Ph 1b dose finding portion (n = 15) was followed by a single arm Ph 2 Simon 2-stage portion (n = 17+20 (37)). The primary endpoint of the Ph 1b portion of the study was safety and recommended Ph 2 dose (RP2D). The secondary endpoints were pharmacokinetics (PK), pharmacodynamics (PD), and clinical benefit rate (CBR = confirmed objective response rate (ORR) + stable disease > 16 weeks). Ph 2 measured CBR as the primary endpoint, ORR and duration of response (DOR) as key secondary endpoints. Eligibility criteria for Ph 1b included TNBC (ER/PR < 10%, HER2-), WT gBRCA1/2, and > 1 prior cytotoxic regimen for mTNBC, and in the Ph2 portion ER/PR < 1% and < 2 prior cytotoxic regimens for mTNBC. Patients were dosed daily in continuous 28 day cycles until disease progression or unacceptable toxicity. Adverse events, PK, and PD in whole blood and tissue biopsies were assessed. Response endpoints were assessed per RECIST 1.1 every 2 cycles. Results: RP2D was determined to be 48mg qd ZEN-3694 plus 0.75mg qd talazoparib. The most common AE for the Ph 1b/2 study was thrombocytopenia (TCP) (55% any grade, 34% G3/4), which was managed with dose holds and reductions. Dose intensity analysis showed average daily doses of ZEN-3694 and talazoparib could be maintained above 40mg and 0.5mg, respectively, over 8 cycles. Robust target engagement was demonstrated using BET-dependent and HRR transcripts assessed in paired tumor biopsies. Ph 2 portion of the trial met its primary endpoint with a CBR of 30% (11/37). For the Ph 1b/2 trial, investgator assessed ORR was 22% (11/50), including 2 CR, CBR was 35% (18/51) and the median DOR was 24 weeks. For the subset of TNBC at diagnosis patients (no history of HR+ disease), ORR was 32% (11/34), and CBR was 44% (15/34). Conclusions: Combination of ZEN-3694 and talazoparib demonstrated anti-cancer activity in pretreated mTNBC WT gBRCA1/2 patients. All confirmed responses were observed in TNBC at diagnosis patients, whose tumors are expected to be more sensitive to the combination due to their basal-like properties. The trial is being expanded to Ph. 2b to accrue an additional 80 TNBC at diagnosis patients. Clinical trial information: NCT03901469.

Oral minoxidil for the treatment of late alopecia in cancer survivors

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 splice variant-7 in breast cancer: clinical and pathologic correlations

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.

Abstract P1-14-03: Adjuvant enzalutamide for the treatment of early-stage androgen-receptor positive, triple negative breast cancer: A feasibility study

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 &lt;1%, HER2 negative) who had completed standard of care therapy were treated with ENZA 160 mg/day orally for 1 year. Patients who completed 1 year had an option to remain on adjuvant ENZA for another year. Toxicity was graded using National Cancer Institute Common Toxicity Criteria (NCI CTCAE) v4. The primary endpoint of this study was to evaluate feasibility of adjuvant ENZA, defined as the discontinuation rate due to toxicity, withdrawal of consent, other events related to tolerability or patient preference. The study was designed to discriminate between feasibility rates of 50% and 70% and was considered feasible if ≥29 out of 46 patients received ENZA for one year without discontinuation. Secondary endpoints included DFS, OS, safety, patient reported outcomes and correlative science. Patients who had disease progression (PD) during year 1 of ENZA without treatment discontinuation due to the above reasons were not included in the primary feasibility analysis but were included in secondary endpoint analyses for survival. Results: 50 patients enrolled on study from 05/2016 - 06/2018. The median age was 58 years (range 34-81 years); 8% had a germline BRCA1/2 (n=3) or PALB2 (n=1) mutation. 38% had stage I disease at diagnosis, 48% stage II and 14% stage III. 74% had grade 3 tumors. 94% of all patients received prior systemic chemotherapy, 81% of whom received prior anthracycline-taxane. 38% (n=19) were treated with prior neoadjuvant chemotherapy and 32% of those patients (n=6) achieved a pCR. Of those who did not achieve a pCR, 69% received adjuvant capecitabine. 47 patients were evaluable for the study endpoint and 35 patients completed 1 year of ENZA thereby meeting the prespecified trial endpoint for feasibility. 32 patients elected to continue into a second year of treatment. After a median follow-up of 140 weeks (range 4 - 236 weeks), 8 patients had a DFS event: 7 TNBC recurrences and 1 new primary breast cancer. The 1-year DFS was 94% (95% CI: 87 - 100%), 2-year DFS was 92% (95% CI: 84 - 99.8%) and the 3-year DFS was 80% (95% CI: 67 - 94%). The median DFS and OS have not yet been reached. Two patients died of TNBC recurrence after 55 and 59 weeks. There were no new or unexpected toxicities observed at study completion. Conclusion: This single-arm trial previously met its primary endpoint of feasibility in patients with early-stage AR+ TNBC. In this relatively high-risk, albeit highly selected patient population, the 3-year DFS measured 80% (95% CI: 67 - 94%) with an adjuvant endocrine therapy approach. Efforts to determine the optimal biomarker for AR+ TNBC are ongoing, so that patients most likely to respond to AR-antagonists in both the early and metastatic setting may be identified. Biomarker data from this study including PD-L1 status and tumor sequencing will be reported at the time of presentation.Funding and drug support for this study was provided by Astellas Pharma Global Development Inc./Pfizer Inc.

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.

Abstract OT1-18-04: 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)

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 [ &gt; 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 &gt;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.

399 A phase II study of nivolumab, ipilimumab, plus androgen receptor blockade with bicalutamide to enhance thymic T-cell production and immunotherapy response in metastatic breast cancer

Background

It 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.2

Methods

This 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 Registration

NCT03650894. The trial is open at Providence Cancer Institute (Portland, OR) and Memorial Sloan Kettering Cancer Center (New York, NY).

References

Velardi 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 Approval

This study was approved by the IRB department and Providence Portland Medical Center, Clinical Trials Department for study NCT03650894.

Consent

Written, informed consent is obtained from each participant.

Abstract PS11-10: A Phase 1b/2 Study of the BET inhibitor ZEN003694 in combination with talazoparib for treatment of patients with TNBC without gBRCA1/2 mutations

Background: Metastatic triple-negative breast cancer (TNBC) is an aggressive and heterogeneous cancer with limited therapeutic options. PARP inhibitors (PARPi) are approved to treat breast cancer harboring germline BRCA1/2 (gBRCA1/2) mutations and have not shown efficacy in homologous recombination DNA repair (HRR) proficient tumors. In pre-clinical models, the BET inhibitor (BETi) ZEN003694 sensitizes wild-type BRCA1/2 tumors to PARPi through downregulation of HRR gene expression, providing a rationale for combination therapy. We report initial results from a Ph 1b/2 trial evaluating the combination of ZEN003694 and the PARPi, talazoparib, in TNBC patients without gBRCA1/2 mutations.

Methods: A Ph 1b dose-finding segment will be followed by a single-arm Ph 2 Simon 2-stage segment. Ph 1b evaluated several dose combinations of ZEN003694 and talazoparib, with safety and recommended Ph 2 dose (RP2D) as primary endpoints and pharmacokinetics (PK), pharmacodynamics (PD), and clinical benefit rate (CBR = Objective response rate (ORR) + stable disease &gt; 4 months) as secondary endpoints. The Ph 2 segment has CBR as the primary endpoint and progression free survival (PFS) and duration of response as secondary endpoints. Eligibility criteria included TNBC (ER/PR &lt; 10% and not a candidate for endocrine therapy), HER2-, wild-type gBRCA1/2, and &gt; 1 prior chemotherapy regimen for metastatic disease. Patients were dosed daily in continuous 28-day cycles until disease progression or unacceptable toxicity. Dose limiting toxicity (DLT) period was one cycle. Adverse events (AE), PK, and PD in whole blood and tissue biopsies were assessed. Response endpoints were assessed per RECIST 1.1 every 2 cycles.

Results: Findings of the Ph 1b are reported. 15 patients with a median 3 lines of prior therapy in the metastatic setting were enrolled in 3 dose-finding cohorts. RP2D was determined to be 48mg ZEN003694 plus 0.75mg talazoparib. Across the cohorts, the most common AE was thrombocytopenia (TCP) (73%) with 53% G3/4 (Table 1). G4 TCP was the DLT and 1 DLT patient required a platelet transfusion. TCP could be managed to G1/2 levels with intermittent dose holds and reductions. Other G1/2 AEs included fatigue, anorexia, neutropenia, nausea, dysgeusia, and photophobia. Dose intensity analysis showed average daily doses of ZEN003694 and talazoparib could be maintained above 40mg and 0.5mg, respectively, over 4 cycles. Exposures of ZEN003694 and talazoparib were dose proportional with no drug-drug PK interactions. At RP2D, PD assessment by a whole blood mRNA assay for BET-dependent genes demonstrated robust down-regulation of CCR1, IL1RN, and IL8 to &lt; 50% of baseline for &gt; 8 h. Expression of HRR genes, RAD51 and BRCA1, in whole blood also decreased for &gt; 8 h. Analysis of an on-treatment biopsy showed robust and durable BET target modulation assessed by comparing RNA sequence data with a reference BET dependent signature. Across the 3 cohorts, ORR by Investigator was 38% (5/13), including 1 CR and 4 PRs, and CBR was 57% (8/14). 6 of the 15 patients are ongoing as of data analysis date (2-9 cycles), with 1 patient responding for &gt; 6 months.

Conclusions: Combination of ZEN003694 and talazoparib demonstrated anti-cancer activity in pretreated metastatic TNBC patients without gBRCA1/2 mutations. TCP is frequent but manageable with dose adjustments. PK is predictable, and PD data show meaningful target engagement. The Ph 2 part of the trial is currently ongoing.

Grade 3/4 Adverse EventsCohort 1(1mg talazoparib + 48mg ZEN003694)N=6Cohort 2(0.75 mg talazoparib + 48mg ZEN003694)N=6Cohort 3(1mg talazoparib + 36mg ZEN003694)N=3Thrombocytopenia3 (G3), 2 (G4, DLT)1 (G3), 1 (G4, DLT)1 (G3)Diarrhea1 (G3)00Neutropenia01 (G3)0

Citation Format: Philippe Aftimos, Mafalda Oliveira, Kevin Punie, Valentina Boni, Erika Hamilton, Ayca Gucalp, Payal Shah, Lida Mina, Priyanka Sharma, Lisa Bauman, Eric Campeau, Sarah Attwell, Margo Snyder, Karen Norek, Akos Czibere, Yanke Yu, Michael H Silverman, Sanjay Lakhotia, Susan Domchek, Jennifer Litton, Mark Robson. A Phase 1b/2 Study of the BET inhibitor ZEN003694 in combination with talazoparib for treatment of patients with TNBC without gBRCA1/2 mutations [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS11-10.

Phase II trial of bicalutamide in combination with palbociclib for the treatment of androgen receptor (+) metastatic breast cancer

1017

Background: Genome-wide transcriptional analysis has identified a unique subset of androgen receptor (AR) +, estrogen receptor (ER)/progesterone receptor (PR)- breast cancer (BC). The functional role of AR was confirmed initially in preclinical models demonstrating that androgen-driven growth could be abrogated by antiandrogen therapy. TBCRC011 established the safety and efficacy of inhibiting AR with bicalutamide (B) in patients (pts) with AR+/ER/PR- metastatic BC (MBC) with a median progression free survival (PFS) of 12 weeks (wks) (95% CI, 11–22 wks). In preclinical data, palbociclib (P) has been shown to reduce growth of AR+/ER/PR- MDA-MB-453 BC cells. It has been shown that AR+ triple negative BC (TNBC) expresses a luminal profile and has intact Rb protein, the target of P activity. We conducted this Phase I/II trial of the AR inhibitor B in combination with the CDK4/6 inhibitor P in pts with AR+/ER/PR/HER2- BC (NCT02605486) to test the hypothesis that androgen blockade, paired with CDK4/6 inhibition would have increased efficacy in pts with androgen-dependent BC. Methods: Postmenopausal pts with AR+ TN MBC defined as IHC ≥ 1% nuclear staining (DAKO, Clone AR441 (5/2016-11/2016) then Ventana AR SP107 (11/2016-6/2018), ECOG ≤2, measurable/non-measurable disease were eligible for enrollment. Any number of prior regimens was permitted. Pts received B 150 mg daily and P 125 mg daily 3 wks on 1 wk off. Pts were evaluated for toxicity every 2-4 wks and for response every 8-12 wks. Primary endpoint: 6 month (mo) PFS. Secondary endpoints: clinical benefit rate, toxicity, correlative studies to better characterize AR+ TNBC. A Simon 2-stage minimax design that discriminates between 6 mo PFS rates of 20% and 40% was used. If ≥ 11/33 pts were PF at 6 mo then B+P would warrant further study. Results: As of 1.1.20 33 pts were enrolled on study with median (med) age 67 (42-79), performance status 0 (0-1). Number of pts with visceral metastases: 20, measurable disease: 22. AR% 1-9: 3, 10-50: 6; 51-100: 24. Med prior lines for MBC: 3 (0-9). Best response: (31 evaluable pts): 11 pts PF at 6mo: 10 SD > 6mo, 1 PR. Med wks on study: 14 (2-101). Toxicity > 10% grade >3 related: Number of pts with leukopenia: 21, neutropenia: 21, lymphocytopenia: 6, thrombocytopenia: 3. One pt with febrile neutropenia. One death due to disease progression within 30 days off study. Conclusions: In this selected subset of pts with AR+ TN MBC, this study met its prespecified endpoint with 11 pts PF at 6 mo on B 150 mg + P 125 mg. B+P has been well tolerated with no unexpected toxicity observed. Clinical trial information: NCT02605486 .

Abstract P4-17-01: Genomic profiling of primary and metastatic breast cancer in men

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.

A phase 2 clinical trial assessing the efficacy and safety of pembrolizumab and radiotherapy in patients with metastatic triple-negative breast cancer

BACKGROUND

The current study was conducted to evaluate the efficacy and safety of pembrolizumab-mediated programmed cell death protein 1 inhibition plus radiotherapy (RT) in patients with metastatic triple-negative breast cancer who were unselected for programmed death-ligand 1 expression.

METHODS

The current study was a single-arm, Simon 2-stage, phase 2 clinical trial that enrolled a total of 17 patients with a median age of 52 years (range, 37-73 years). An RT dose of 3000 centigrays (cGy) was delivered in 5 daily fractions. Pembrolizumab was administered intravenously at a dose of 200 mg within 3 days of the first RT fraction, and then every 3 weeks ± 3 days until disease progression. The median follow-up was 34.5 weeks (range, 2.1-108.3 weeks). The primary endpoint of the current study was the overall response rate (ORR) at week 13 in patients with unirradiated lesions measured using Response Evaluation Criteria in Solid Tumors (RECIST; version 1.1). Secondary endpoints included safety and progression-free survival. Exploratory objectives were to identify biomarkers predictive of ORR and progression-free survival.

RESULTS

The ORR for the entire cohort was 17.6% (3 of 17 patients; 95% CI, 4.7%-44.2%), with 3 complete responses (CRs), 1 case of stable disease, and 13 cases of progressive disease. Eight patients died prior to week 13 due to disease progression. Among the 9 women assessed using RECIST version 1.1 at week 13, 3 (33%) achieved a CR, with a 100% reduction in tumor volume outside of the irradiated portal. The CRs were durable for 18 weeks, 20 weeks, and 108 weeks, respectively. The most common grade 1 to 2 toxicity (assessed according to the National Cancer Institute Common Terminology Criteria for Adverse Events, version 4.0) was dermatitis (29%). Four grade 3 adverse events were attributed to pembrolizumab: fatigue, lymphopenia, and infection. No were no grade 4 adverse events or treatment-related deaths reported.

CONCLUSIONS

The combination of pembrolizumab and RT was found to be safe and demonstrated encouraging activity in patients with poor-prognosis, metastatic, triple-negative breast cancer who were unselected for programmed death-ligand 1 expression. Larger clinical trials of checkpoint blockade plus RT with predictive biomarkers of response are needed.

Efficacy and Safety of Gemcitabine With Trastuzumab and Pertuzumab After Prior Pertuzumab-Based Therapy Among Patients With Human Epidermal Growth Factor Receptor 2-Positive Metastatic Breast Cancer: A Phase 2 Clinical Trial

IMPORTANCE

Taxanes with trastuzumab and pertuzumab for initial treatment of human epidermal growth factor receptor 2 (ERBB2, formerly HER2)-positive metastatic breast cancer is associated with improved progression-free survival (PFS) and overall survival. While continued use of trastuzumab in therapeutic combinations after disease progression is standard, the efficacy of continuing pertuzumab is unknown.

OBJECTIVE

To evaluate the efficacy and safety of pertuzumab in combination with gemcitabine and trastuzumab after prior treatment with pertuzumab for ERBB2-positive metastatic breast cancer.

DESIGN, SETTING, AND PARTICIPANTS

This is a phase 2 single-arm clinical trial of dual anti-ERBB2 therapy after prior treatment with pertuzumab. The study took place at a single academic center from March 2015 to April 2017 among women with ERBB2-positive metastatic breast cancer, prior pertuzumab-based treatment, and 3 or fewer prior chemotherapy regimens. Data were analyzed between January 2019 and March 2019.

INTERVENTION

Treatment consisted of gemcitabine, 1200 mg/m2 (later amended to 1000 mg/m2) on days 1 and 8 every 3 weeks, plus trastuzumab (8-mg/kg loading dose, then 6 mg/kg) and pertuzumab (840-mg loading dose, then 420 mg) once every 3 weeks.

MAIN OUTCOMES AND MEASURES

The primary end point was 3-month PFS. Based on prior trials, a target rate of 70% or higher was selected as the promising progression-free rate at 3 months. Secondary outcomes included safety, tolerability, and overall survival.

RESULTS

A total of 45 patients (median [range] age, 57.1 [31.7-77.2] years) were enrolled; 22 (49%) were treated in the second-line setting, and 23 (51%) were treated in the third-line setting or beyond. Of these, 22 (49%) received prior trastuzumab emtansine (T-DM1). At a median (range) follow-up of 27.6 (8.3-36.0) months, 3-month PFS was 73.3% (95% CI, 61.5%-87.5%). Overall, median PFS was 5.5 months (95% CI, 5.4-8.2 months). Treatment was well tolerated, with no occurrences of febrile neutropenia or symptomatic left ventricular systolic dysfunction.

CONCLUSIONS AND RELEVANCE

In this phase 2 trial, treatment with gemcitabine, trastuzumab, and pertuzumab after prior pertuzumab-based therapy for ERBB2-positive metastatic breast cancer was associated with a 3-month PFS rate of 73.3% and was well tolerated. Continuation of pertuzumab beyond progression was associated with apparent clinical benefit.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT02252887.

Mammographic screening in male patients at high risk for breast cancer: is it worth it?

PURPOSE

To investigate the utility of mammography for breast cancer screening in a population of males at increased risk for breast cancer.

METHODS

In this HIPAA-compliant institutional review board-approved single-institution study, mammography records and clinical data of 827 male patients who underwent digital mammography from September 2011-July 2018 were analyzed via the electronic medical record. 664 of these men presented with masses, pain, or nipple discharge and were excluded from this study. The remaining 163 asymptomatic men with familial and/or personal history of breast cancer, or with a known germline mutation in BRCA, underwent screening mammography and were included in this analysis.

RESULTS

163 asymptomatic men (age: mean 63 years, range 24-87 years) underwent 806 screening mammograms. 125/163 (77%) had a personal history of breast cancer and 72/163 (44%) had a family history of breast cancer. 24/163 (15%) were known mutation carriers: 4/24 (17%) BRCA1 and 20/24 (83%) BRCA2. 792/806 (98%) of the screening mammograms were negative (BI-RADS 1 or 2); 10/806 (1.2%) were classified as BI-RADS 3, all of which were eventually downgraded to BI-RADS 2 on follow-up. 4/806 (0.4%) mammograms were abnormal (BI-RADS 4/5): all were malignant. The cancer detection rate in this cohort was 4.9 cancers/1000 examinations.

CONCLUSIONS

In our cohort, screening mammography yielded a cancer detection rate of 4.9 cancers/1000 examinations which is like the detection rate of screening mammography in a population of women at average risk, indicating that screening mammography is of value in male patients at high risk for breast cancer.

Adjuvant enzalutamide for the treatment of early-stage androgen receptor-positive (AR+) TNBC

546

Background: A subset of TNBC is dependent on AR signaling. Enzalutamide (ENZA), an AR-antagonist, has activity in patients (pts) with metastatic AR+ TNBC, with a clinical benefit rate of 33%. This study tests the feasibility of adjuvant ENZA for the treatment (tx) of early stage, AR+ TNBC. We now report the primary endpoint (endpt) and safety. Methods: Eligible pts have centrally confirmed, Stage I-III, ER/PR < 1%, HER2(-), AR ≥1% BC and completed all planned surgery, chemotx and radiation (RT) < 6 months of tx start. AR testing by IHC per MSK methods. Tx consists of ENZA 160mg daily for 1 year (y) with the option to extend tx to 2y. Toxicity per NCI CTCAEv4 every (q) 4 weeks (wk) for 12 wk, then q3 months. Primary endpt: feasibility of 1y ENZA defined as the discontinuation rate due to toxicity, consent withdrawal or tolerability. 50 pts are enrolled to have 46 evaluable pts required to discriminate between feasibility of 50% and 70%, with type I error 5% and 88% power. Pts who have disease progression (PD) or die during 1st y of ENZA and do not have tx discontinuation due to the above will not be included in the primary analysis. If 29 pts complete 1y, adjuvant ENZA will be deemed feasible. Secondary endpts: safety and 3y DFS and OS. Exploratory endpts: PROs and biomarker development. Results: Between 5/2016-6/2018, 50 pts were enrolled. Pt and tumor characteristics (N = 50): Median age 55y (33-81); Stage: I 20 (40%), II 23 (46%), III 7 (14%); Grade (gr): 2 = 26%, 3 = 74%. AR > 10% = 35 (70%), AR ≤10% = 15 (30%). Chemotx 47/50 (94%): Neoadjuvant (neo) 40%, Adjuvant (adj) 60%; Anthracycline/Taxane-based 38/47 (81%), Platinum 1/47 (2%), Docetaxel/Cyclophosphamide 3/47 (6%), other 5/47 (11%). 13/19 who received neo tx failed pCR; 9/13 (69.2%) received adj capecitabine. RT: 38/50 (76%). 27 pts completed 1y of tx. 7 pts will be evaluable by 6/1/19. 1 pt to complete 1y 6/21/19. 15 pts are off tx: PD (3), toxicity (5), noncompliance (4), withdrawal of consent (3). Tx-related AEs, any gr, > 10% (N = 50): fatigue (48%), hot flashes (22%), headache (18%), hyperglycemia (18%), nausea (18%), WBC decreased (16%), dizziness (14%), arthralgia (12%), dyspnea (12%). Tx-related, gr 3 AEs: fatigue (6%), hyperglycemia (2%), hypertension (2%). No gr 4/5 AEs or seizures. 11 pts had dose reduction. Conclusions: Feasibility of adjuvant ENZA will be fully evaluable in 4/2019 and is anticipated to meet the prespecified statistical expectations for primary endpt. ENZA is well tolerated following locoregional tx and standard of care systemic tx. Secondary analyses and correlatives are ongoing to define the role of AR in TNBC. Clinical trial information: NCT02750358.

Improving risk assessment of obesity-associated breast cancer

1544

Background: Elevated body mass index (BMI) is associated with increased risk of estrogen receptor (ER)-positive postmenopausal breast cancer. The risk is also elevated in women with a normal BMI but excess body fat. These risks may be driven by breast white adipose tissue inflammation (WATi), which is associated with elevated aromatase levels and systemic metabolic dysfunction (e.g. hyperinsulinemia). We hypothesized that body fat assessment is superior to BMI for detecting the pathophysiology that promotes obesity-related breast cancer, particularly among normal BMI women. Methods: Non-tumorous breast tissue was collected from women undergoing mastectomy for breast cancer treatment or prevention. Breast WATi was detected by the presence of crown-like structures in the breast, which are composed of a dead/dying adipocyte surrounded by CD68+ macrophages. Body composition was measured prior to mastectomy via dual energy X-ray absorptiometry. Exercise behavior was also assessed prior to surgery using the Godin Leisure Time Exercise Questionnaire. Associations among categorical variables were examined using Χ2 or Fisher’s exact test. Relationships between continuous variables were examined using the Spearman correlation. Results: From April 5, 2016 to August 31, 2018, 100 patients were enrolled; median age 49 (range 29 to 82) years. Breast WATi was present in 56/100 (56%) women and was associated with elevated BMI and body fat levels, breast adipocyte hypertrophy, postmenopausal status, metabolic syndrome and decreased physical activity (P < 0.05). Among 39 women with normal BMI, breast WATi was present in 14 (36%) and was associated with elevated body fat levels, breast adipocyte hypertrophy, dyslipidemia, and decreased physical activity (P < 0.05). There was no statistically significant association between BMI and breast WATi in the normal BMI group. Menopausal status and total fat mass had greater sensitivity and specificity for the detection of breast WATi compared to a BMI-based model (AUC 0.843 vs. 0.779, respectively). Conclusions: Measurement of body fat is superior to BMI for predicting breast inflammation, which has been shown to promote obesity-related breast cancer.

A phase II study of dual immune checkpoint blockade (ICB) plus androgen receptor (AR) blockade to enhance thymic T-cell production and immunotherapy response in metastatic breast cancer (MBC)

TPS1106

Background: ICB (atezolizumab, anti-PD-L1) is known to improve survival when added to chemo, however only in PD-L1-positive, triple-negative MBC. ICB is less effective in hormone receptor positive (HR+) MBC, or when administered following palliative chemo. Novel approaches are required to broaden clinical benefit of ICB, particularly in PD-L1-negative, HR+, or chemo-experienced MBC. Dual ICB with anti-PD-1 (nivolumab) and anti-CTLA-4 (ipilimumab) is associated with enhanced activity in melanoma other malignancies, but has not been explored extensively in MBC. Androgen receptor (AR) blockade, in addition to known direct cytostatic effects in AR-expressing MBCs (50% of TNBC, > 75% of HR+ MBC), may also modulate immune response. AR blockade has been shown experimentally to stimulate thymic production of naïve T-cell clones, which in turn can facilitate de novo anti-tumor immune responses. Concurrent ICB can enhance the activity of these T-cell clones by interfering with PD-1-mediated peripheral tolerance. This combination approach is promising in MBC in light of known AR positivity, and the routine use of lymphodepleting chemo regimens in the curative-intent setting. Methods: This is a phase II trial of dual immune checkpoint blockade (nivolumab 240mg IV q2w; ipilimumab 1mg/kg IV q6w) plus AR blockade (bicalutamide, 150mg PO daily, dose reduction allowed) in triple-negative MBC (cohort A: AR-positive [ > 1% by IHC]; cohort B: AR-negative) or HR+ MBC (cohort C) in subjects who received 0/1 prior chemotherapies in the non-curative setting. Objectives include 24-week clinical benefit rate by iRECIST (primary), safety (CTCAE v4.0), and other response measures (RECIST1.1, PFS, OS). Efficacy for each cohort is defined as > 20% improvement in response over historical control (30% per EMBRACE clinical trial) employing a Simon 2-stage design to minimize futility (n = 46/cohort, stage I n = 15). Thymic generation of T-cells will be measured via quantitative deep sequencing of T-cell receptors (TcR, ImmunoSEQ assay) and TcR excision circles (TRECs), as well as real-time flow cytometry using surrogate cell surface markers of recent thymic emigration. Enrollment has commenced, sites: Earle A. Chiles Research Institute (Portland, OR), Memorial Sloan Kettering Cancer Center (New York, NY). Clinical trial information: NCT03650894.

"A Tool, Not a Crutch": Patient Perspectives About IBM Watson for Oncology Trained by Memorial Sloan Kettering

PURPOSE

IBM Watson for Oncology trained by Memorial Sloan Kettering (WFO) is a clinical decision support tool designed to assist physicians in choosing therapies for patients with cancer. Although substantial technical and clinical expertise has guided the development of WFO, patients' perspectives of this technology have not been examined. To facilitate the optimal delivery and implementation of this tool, we solicited patients' perceptions and preferences about WFO.

METHODS

We conducted nine focus groups with 46 patients with breast, lung, or colorectal cancer with various treatment experiences: neoadjuvant/adjuvant chemotherapy, chemotherapy for metastatic disease, or systemic therapy through a clinical trial. In-depth qualitative and quantitative data were collected and analyzed to describe patients' attitudes and perspectives concerning WFO and how it may be used in clinical care.

RESULTS

Analysis of the qualitative data identified three main themes: patient acceptance of WFO, physician competence and the physician-patient relationship, and practical and logistic aspects of WFO. Overall, participant feedback suggested high levels of patient interest, perceived value, and acceptance of WFO, as long as it was used as a supplementary tool to inform their physicians' decision making. Participants also described important concerns, including the need for strict processes to guarantee the integrity and completeness of the data presented and the possibility of physician overreliance on WFO.

CONCLUSION

Participants generally reacted favorably to the prospect of WFO being integrated into the cancer treatment decision-making process, but with caveats regarding the comprehensiveness and accuracy of the data powering the system and the potential for giving WFO excessive emphasis in the decision-making process. Addressing patients' perspectives will be critical to ensuring the smooth integration of WFO into cancer care.

Phase 1 study of seviteronel, a selective CYP17 lyase and androgen receptor inhibitor, in women with estrogen receptor-positive or triple-negative breast cancer

PURPOSE

Seviteronel (INO-464) is an oral, selective cytochrome P450c17a (CYP17) 17,20-lyase (lyase) and androgen receptor inhibitor with in vitro and in vivo anti-tumor activity. This open-label phase 1 clinical study evaluated safety, tolerability, pharmacokinetics (PK), and activity of once-daily (QD) seviteronel in women with locally advanced or metastatic TNBC or ER+ breast cancer.

METHODS

Seviteronel was administered in de-escalating 750, 600, and 450 mg QD 6-subject cohorts. The 750 mg QD start dose was a phase 2 dose determined for men with castration-resistant prostate cancer in (Shore et al. J Clin Oncol 34, 2016). Enrollment at lower doses was initiated in the presence of dose-limiting toxicities (DLTs). The primary objective of this study was to determine seviteronel safety, tolerability, and MTD. The secondary objectives included description of its PK in women and its initial activity, including clinical benefit rate at 4 (CBR16) and 6 months (CBR24).

RESULTS

Nineteen women were enrolled. A majority of adverse events (AEs) were Grade (Gr) 1/2, independent of relationship; the most common were tremor (42%), nausea (42%), vomiting (37%), and fatigue (37%). Four Gr 3/4 AEs (anemia, delirium, mental status change, and confusional state) deemed possibly related to seviteronel occurred in four subjects. DLTs were observed at 750 mg (Gr 3 confusional state with paranoia) and 600 mg (Gr 3 mental status change and Gr 3 delirium) QD, with none at 450 mg QD. The recommended phase 2 dose (RP2D) was 450 mg QD, and at the RP2D, 4 of 7 subjects reached at least CBR16 (2 TNBC subjects and 2 ER+ subjects achieved CBR16 and CBR24, respectively); no objective tumor responses were reported.

CONCLUSIONS

Once-daily seviteronel was generally well tolerated in women with and 450 mg QD was chosen as the RP2D.

Leptin regulation of the p53-HIF1α/PKM2-aromatase axis in breast adipose stromal cells: a novel mechanism for the obesity-breast cancer link

BACKGROUND/OBJECTIVES

Obesity (body mass index (BMI)⩾30 kg m-2) is associated with an increased risk of estrogen-dependent breast cancer after menopause. Levels of aromatase, the rate-limiting enzyme in estrogen biosynthesis, are elevated in breast tissue of obese women. Recently, the regulation of aromatase by the p53-hypoxia-inducible factor-1α (HIF1α)/pyruvate kinase M2 (PKM2) axis was characterized in adipose stromal cells (ASCs) of women with Li-Fraumeni Syndrome, a hereditary cancer syndrome that predisposes to estrogen-dependent breast cancer. The current study aimed to determine whether stimulation of aromatase by obesity-associated adipokine leptin involves the regulation of the p53-HIF1α/PKM2 axis.

SUBJECTS/METHODS

Human breast ASCs were used to characterize the p53-HIF1α/PKM2-aromatase axis in response to leptin. The effect of pharmacological or genetic modulation of protein kinase C (PKC), mitogen-activated protein kinase (MAPK), p53, Aha1, Hsp90, HIF1α and PKM2 on aromatase promoter activity, expression and enzyme activity was examined. Semiquantitative immunofluorescence and confocal imaging were used to assess ASC-specific protein expression in formalin-fixed paraffin-embedded tissue sections of breast of women and mammary tissue of mice following a low-fat (LF) or high-fat (HF) diet for 17 weeks.

RESULTS

Leptin-mediated induction of aromatase was dependent on PKC/MAPK signaling and the suppression of p53. This, in turn, was associated with an increase in Aha1 protein expression, activation of Hsp90 and the stabilization of HIF1α and PKM2, known stimulators of aromatase expression. Consistent with these findings, ASC-specific immunoreactivity for p53 was inversely associated with BMI in breast tissue, while HIF1α, PKM2 and aromatase were positively correlated with BMI. In mice, HF feeding was associated with significantly lower p53 ASC-specific immunoreactivity compared with LF feeding, while immunoreactivity for HIF1α, PKM2 and aromatase were significantly higher.

CONCLUSIONS

Overall, findings demonstrate a novel mechanism for the obesity-associated increase in aromatase in ASCs of the breast and support the study of lifestyle interventions, including weight management, which may reduce breast cancer risk via effects on this pathway.

Enzalutamide for the Treatment of Androgen Receptor-Expressing Triple-Negative Breast Cancer

Purpose Studies suggest that a subset of patients with triple-negative breast cancer (TNBC) have tumors that express the androgen receptor (AR) and may benefit from an AR inhibitor. This phase II study evaluated the antitumor activity and safety of enzalutamide in patients with locally advanced or metastatic AR-positive TNBC. Patients and Methods Tumors were tested for AR with an immunohistochemistry assay optimized for breast cancer; nuclear AR staining > 0% was considered positive. Patients received enzalutamide 160 mg once per day until disease progression. The primary end point was clinical benefit rate (CBR) at 16 weeks. Secondary end points included CBR at 24 weeks, progression-free survival, and safety. End points were analyzed in all enrolled patients (the intent-to-treat [ITT] population) and in patients with one or more postbaseline assessment whose tumor expressed ≥ 10% nuclear AR (the evaluable subgroup). Results Of 118 patients enrolled, 78 were evaluable. CBR at 16 weeks was 25% (95% CI, 17% to 33%) in the ITT population and 33% (95% CI, 23% to 45%) in the evaluable subgroup. Median progression-free survival was 2.9 months (95% CI, 1.9 to 3.7 months) in the ITT population and 3.3 months (95% CI, 1.9 to 4.1 months) in the evaluable subgroup. Median overall survival was 12.7 months (95% CI, 8.5 months to not yet reached) in the ITT population and 17.6 months (95% CI, 11.6 months to not yet reached) in the evaluable subgroup. Fatigue was the only treatment-related grade 3 or higher adverse event with an incidence of > 2%. Conclusion Enzalutamide demonstrated clinical activity and was well tolerated in patients with advanced AR-positive TNBC. Adverse events related to enzalutamide were consistent with its known safety profile. This study supports additional development of enzalutamide in advanced TNBC.

A Randomized Multicenter Phase II Study of Docosahexaenoic Acid in Patients with a History of Breast Cancer, Premalignant Lesions, or Benign Breast Disease

Obesity, a cause of subclinical inflammation, is a risk factor for the development of postmenopausal breast cancer and is associated with poorer cancer outcomes. Docosahexaenoic acid (DHA), an omega-3 fatty acid, possesses anti-inflammatory properties. We hypothesized that treatment with DHA would reduce the expression of proinflammatory genes and aromatase, the rate-limiting enzyme for estrogen biosynthesis, in benign breast tissue of overweight/obese women. A randomized, placebo-controlled, double-blind phase II study of DHA given for 12 weeks to overweight/obese women with a history of stage I-III breast cancer, DCIS/LCIS, Paget's disease, or proliferative benign breast disease was carried out. In this placebo controlled trial, the primary objective was to determine whether DHA (1,000 mg by mouth twice daily) reduced breast tissue levels of TNFα. Secondary objectives included evaluation of the effect of DHA on breast tissue levels of COX-2, IL1β, aromatase, white adipose tissue inflammation, and gene expression by RNA-seq. Red blood cell fatty acid levels were measured to assess compliance. From July 2013 to November 2015, 64 participants were randomized and treated on trial (32 women per arm). Increased levels of omega-3 fatty acids in red blood cells were detected following treatment with DHA (P < 0.001) but not placebo. Treatment with DHA did not alter levels of TNFα (P = 0.71), or other biomarkers including the transcriptome in breast samples. Treatment with DHA was overall well-tolerated. Although compliance was confirmed, we did not observe changes in the levels of prespecified biomarkers in the breast after treatment with DHA when compared with placebo. Cancer Prev Res; 11(4); 203-14. ©2018 AACRSee related editorial by Fabian and Kimler, p. 187.

Abstract P3-10-04: Obesity and adipose inflammation in men with breast cancer

Background: Elevated body mass index (BMI) is associated with increased risk of hormone receptor (HR)-positive breast cancer in postmenopausal women and worsened outcomes after breast cancer diagnosis. These observations may be partly attributable to adipose inflammation, which is prevalent in the breasts of obese women and is associated with worsened breast cancer survival. In men, some studies have reported obesity to be a risk factor for breast cancer, however the biologic links are not well characterized. Whether adipose inflammation occurs in male breast tissue has not been previously reported. Here we examined the relationships among pre-diagnosis BMI, adipose inflammation, and breast cancer features in men.

Methods: Males diagnosed with stage 0 – III breast cancer who underwent mastectomy at Memorial Sloan Kettering (MSK) between August 1991 – November 2011 were included in this retrospective cohort study. Pre-operative BMI was categorized as normal or underweight (&lt;25), overweight (25 – 29.9), obese (≥30), or morbidly obese (≥40 or ≥35 + co-morbidity). Archived breast tissue was subjected to CD68 immunohistochemistry to detect adipose inflammation, defined by the presence of dead or dying adipocytes surrounded by macrophages – known as crown-like structures of the breast (CLS-B). Clinicopathologic associations with BMI and CLS-B were analyzed by logistic regression and Fisher's exact test.

Results: A total of 141 men were included; median age 63 (range 23 – 96). By BMI category, 25 were normal or underweight, 65 overweight, and 51 obese – of which 19 were morbidly obese. Only 11 men had known BRCA1/2 mutations. Median age at diagnosis was 69 in normal/underweight men versus 63 in obese men and 51 in morbidly obese men (P≤0.05). Among those with invasive tumors, average tumor size was 1.50 cm (± 0.84) in normal/underweight men versus 2.04 (±0.81) in morbidly obese men (P≤0.05). Archived breast tissue was available from 92 (65%) men. Breast adipose inflammation was present in 55 (60%) men, and average BMI was 31 (±8) versus 28 (±5) in men with versus without inflammation, respectively (P=0.07).

Conclusions: Obesity is associated with early onset breast cancer in men. Morbidly obese men were diagnosed with breast cancer at an even younger age and had larger tumors than normal weight individuals. These findings support further studies to investigate mechanisms, such as adipose inflammation, through which obesity may promote breast cancer in men.

Citation Format: Williams S, Parrish JC, Zhou XK, Wang H, Dierickx A, Gucalp A, Dannenberg AJ, Iyengar NM. Obesity and adipose inflammation in men with breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P3-10-04.

A single-arm, phase II study assessing the efficacy of pembrolizumab (pembro) plus radiotherapy (RT) in metastatic triple negative breast cancer (mTNBC)

14

Background: Overall response rates of 13-19% have been reported with checkpoint inhibitor monotherapy in chemotherapy-resistant, PD-L1-positive mTNBC. RT is frequently used to enhance local control in mTNBC and has been reported to induce distant (abscopal) tumor responses when combined with immunotherapy. In this study, we evaluate the safety and efficacy of RT combined with a programmed cell death protein 1 (PD-1) inhibitor, pembro, in a single-arm, two-stage, phase II study in mTNBC. Methods: Eligible women had biopsy-proven mTNBC, ECOG performance status 0-2, and ≥2 measurable sites of metastatic disease with at least one site requiring RT. A total RT dose of 3000 cGy was delivered in 5 daily fractions. Pembro 200 mg was given intravenously within 3 days of first RT fraction, then every 3 weeks +/-3 days until disease progression. The primary endpoint was overall response rate at week 13 in the non-irradiated lesions by RECIST v1.1. Secondary endpoints included safety and overall survival. Tumor biopsies were obtained at baseline and at week 7. PD-L1 expression was not required for study entry. Results: Of the 17 women enrolled, the median age was 52 y (range 37-73y). and the median number of prior chemotherapies received for metastatic disease was 3 (range 0 to 8). Of the 8 women not evaluable at 13 weeks: 5 died secondary to disease-related complications (at weeks 2, 6, 7, 8, and 9) and 3 came off study due to disease progression prior to week 13. Of the 9 women evaluable at week 13, 3 (33%) had a partial response, 1 (11%) had stable disease and 5 (56%) had disease progression. The 3 partial responses represented 60%, 54%, and 34% decreases in tumor burden by RECIST v1.1 and were durable for 31, 21, and ongoing at 22 weeks, respectively. The stable disease response was durable for 22 weeks. Common toxicities were mild and included fatigue, myalgia and nausea. Conclusions: The combination of pembro and RT is well-tolerated. This is a poor prognosis population with 5/17 (29%) of patients dying within 12 weeks of study entry. However, durable responses were observed outside of the RT field in 3/9 (33%) patients who were unselected for PD-L1 expression and evaluable at 13 weeks. Clinical trial information: NCT02730130.

Phase (Ph) 2 stage 1 clinical activity of seviteronel, a selective CYP17-lyase and androgen receptor (AR) inhibitor, in women with advanced AR+ triple-negative breast cancer (TNBC) or estrogen receptor (ER)+ BC: CLARITY-01

1102

Background: Seviteronel (Sevi), an oral selective CYP17-lyase and AR inhibitor that blocks testosterone and estradiol production and competitively antagonizes the AR, is in Ph 2 clinical development for BC and prostate cancer. The primary objective of this ongoing Ph 2 study (NCT02580448) is to estimate the activity of once daily Sevi in women with AR+ TNBC and ER+ BC as measured by clinical benefit rate (CBR) at 16 and 24 weeks (wk), respectively. Methods: Patients (pts) with ER+/HER2-normal metastatic BC following progression of ≥1 prior line of endocrine therapy or TNBC were enrolled with no limit of prior therapies in either cohort. Evaluable pts had AR ≥10% via central IHC staining (TNBC only) and 1 post-baseline scan. Sevi was administered at 450 mg oral daily. Scans were performed every 8 wk. Circulating tumor cell (CTC) enumeration was performed by EPIC CTC analysis. A Simon’s 2-stage design was employed to determine activity (≥2 of 13 CBR16 in TNBC and ≥2 of 12 CBR24 in ER+ BC allow for accrual to Stage 2). Results: As of 4 Oct, 2016, 16 pts with AR+ TNBC (6 evaluable) and 14 pts with ER+ BC (11 evaluable) were enrolled. 67% had visceral metastases; 10% had stable brain metastases. 60% had ≥2 lines of prior therapy for advanced disease. 13 of 14 (93%) TNBC pts who underwent central AR testing had AR ≥10%. Four pts in the TNBC cohort and 8 pts in the ER+ cohort remain on therapy. CBR16 (TNBC) and CBR24 (ER+) was 2 of 6 (33%) and 2 of 11 (18%) allowing Stage 2 accrual in both cohorts. 7 of 10 evaluable pts with CTCs present at baseline had a CTC decline at C2D1, including all that met CBR (-94.3% [-27.5, -100] median [range]). The most common adverse events (≥ 25%) were fatigue (50%), nausea (43%) and decreased appetite (33%); all Grade 1/2. Updated CBR data will be presented at the time of presentation. Conclusions: Sevi Stage 1 activity is suggested by CBRs, along with associated CTC declines in heavily pre-treated pts with high disease burden. The observed safety profile is consistent with on-target pharmacology. Stage 2 enrollment is ongoing. Sevi may provide a novel treatment option for women with AR+ TNBC or ER+ BC. Clinical trial information: NCT02580448.

Overall survival (OS) in patients (Pts) with diagnostic positive (Dx+) breast cancer: Subgroup analysis from a phase 2 study of enzalutamide (ENZA), an androgen receptor (AR) inhibitor, in AR+ triple-negative breast cancer (TNBC) treated with 0-1 prior lines of therapy

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Background: The AR may be a novel therapeutic target for pts with AR-driven TNBC. ENZA, a potent AR inhibitor approved in men with metastatic prostate cancer, was evaluated in this phase 2 study of pts with AR+ TNBC. A genomic signature associated with AR-driven biology was identified; updated OS results in pts treated with 0-1 prior lines of therapy are presented. Methods: This is an open-label, Simon two-stage study (NCT01889238) of ENZA monotherapy in advanced AR+ TNBC (AR > 0% by IHC). Bone-only disease and unlimited prior regimens were allowed; CNS metastases or seizure history were exclusionary. The primary endpoint was clinical benefit rate at 16 weeks (CBR16) in evaluable pts (AR > 10% and ≥1 postbaseline assessment). OS was an exploratory endpoint. Results in intent-to-treat (ITT) and evaluable pts were presented previously (Traina TA et al. J Clin Oncol. 2015;33:1003). Results: 118 pts were enrolled (ITT). CBR16 in 78 evaluable pts was 33.3%. Of the 118 ITT pts, 56 were Dx+ and 62 were Dx–; ≥50% received 0-1 prior lines of therapy (28 Dx+, 37 Dx–). As of 26 Nov 2016 there were 83 deaths (median follow-up 28 mo); median OS (mOS) was 13 mo (95% CI; 8-18). In the Dx+ subgroup there were 32 deaths (mOS 20 mo [95% CI; 13-29]) vs 51 deaths in the Dx– subgroup (mOS 8 mo [95% CI; 5-11]). In pts with 0-1 prior lines of therapy, there were 13 deaths in the Dx+ subgroup (mOS 29 mo [95% CI; 19-not reached] vs 28 in the Dx– subgroup (mOS 10 mo [95% CI; 7-15]). The most common adverse events (AEs) were fatigue and nausea; fatigue was the only grade 3 related AE in > 5% of pts. A multi-covariate Cox analysis identified Dx status (+ vs –) and line of therapy (0-1 vs ≥2) as the only variables significantly associated with OS. Conclusions: In this study, the mOS of pts with Dx+ TNBC who received 0-1 prior lines of therapy appears longer than that of unselected historic controls. ENZA may represent a therapeutic option in pts with AR+ TNBC who would otherwise receive cytotoxic chemotherapy and is currently being evaluated in ENDEAR, a phase 3 study in pts with Dx+ advanced TNBC and 0-1 prior lines of therapy. Clinical trial information: NCT01889238.

Phase II study of gemcitabine (G), trastuzumab (H), and pertuzumab (P) for HER2-positive metastatic breast cancer (MBC) after prior pertuzumab-based therapy

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Background: The combination of taxanes with HP for first line treatment of HER2-positive MBC is associated with improved progression-free (PFS) and overall survival (OS). Treatment per physician’s choice with anti-HER2 therapy after second line therapy is associated with a median PFS of 3 months. While continued use of H in therapeutic combinations after progression on H-based therapy is standard, the efficacy of continuing HP-based treatment after progression on P-based therapy is unknown. Methods: This is a single arm phase II trial of G with HP. Eligible patients (pts) had HER2-positive (IHC 3+ or FISH > 2.0) MBC with prior HP-based treatment and ≤ 3 prior chemotherapies. Pts received G (1200 mg/m2) on days 1 and 8 of a q 3 week (w) cycle, and H (8 mg/kg load → 6 mg/kg) and P (840 mg load → 420 mg) q3w. The primary endpoint is PFS at 3 months. Secondary endpoints include OS, safety and tolerability. An exploratory endpoint is to compare PFS by RECIST criteria versus 18-F FDG-PET response criteria. The study therapy will be considered successful if at least 27/45 (60%) patients are progression free at 3 months. Results: As of 1-27-17, 41 of 45 pts are enrolled; 34 are evaluable at 3 months and 7 have not had 3-month evaluation. At 3 months, 26/34 (76%) are progression free (1 CR, 8 PR, 17 SD); 8 pts progressed. There are no cardiac or febrile neutropenic events to date. 4 pts required G dose reduction (3 grade 3 neutropenia and 1 grade 3 vomiting) and the study was amended to lower initial G dose to 1000 mg/m2. Conclusions: The preliminary 3 month-PFS is 76% in evaluable pts (95% CI 60% to 88%). The updated 3 month-PFS results will be presented. Continuation of P beyond progression is associated with apparent clinical benefit. A randomized trial is justified to confirm this clinically important observation. Clinical trial information: NCT02252887.

Menopause Is a Determinant of Breast Aromatase Expression and Its Associations With BMI, Inflammation, and Systemic Markers

CONTEXT

Most estrogen-dependent breast cancers occur after menopause, despite low levels of circulating estrogens. Breast expression of the estrogen-biosynthetic enzyme, aromatase, is proposed to drive breast cancer development after menopause. However, the effects of menopause on breast aromatase expression are unknown.

OBJECTIVE

To determine the effect of menopause on breast aromatase expression in relation to body mass index (BMI), white adipose tissue inflammation (WATi), and systemic markers of metabolic dysfunction.

DESIGN, SETTING, AND PARTICIPANTS

Cross-sectional study of 102 premenopausal (age 27 to 56) and 59 postmenopausal (age 45 to 74) women who underwent mastectomy for breast cancer treatment/prevention.

OUTCOME

Breast tissue was assessed for the presence of crown-like structures and the expression and activity of aromatase. Systemic markers examined include interleukin (IL)-6, insulin, glucose, leptin, adiponectin, high-sensitivity C-reactive protein (hsCRP), cholesterol, and triglycerides. Multivariable analysis was performed for aromatase messenger RNA (mRNA) in relation to BMI, WATi, and blood markers.

RESULTS

Postmenopausal women had higher BMI and more breast WATi than premenopausal women. Fasting levels of IL-6, glucose, leptin, hsCRP, and homeostatic model assessment 2 insulin resistance score were higher in the postmenopausal group. BMI was positively correlated with aromatase mRNA in both pre- and postmenopausal women. Aromatase levels were higher in breast tissue of postmenopausal women, with levels being higher in inflamed vs noninflamed, independent of BMI. Adipocyte diameter and levels of leptin, hsCRP, adiponectin, and high-density lipoprotein cholesterol were more strongly correlated with aromatase in postmenopausal than premenopausal women.

CONCLUSIONS

Elevated aromatase in the setting of adipose dysfunction provides a possible mechanism for the higher incidence of hormone-dependent breast cancer in obese women after menopause.

A Phase I/Ib Study of Enzalutamide Alone and in Combination with Endocrine Therapies in Women with Advanced Breast Cancer

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.

Metabolic Obesity, Adipose Inflammation and Elevated Breast Aromatase in Women with Normal Body Mass Index

Obesity is associated with breast white adipose tissue (WAT) inflammation, elevated levels of the estrogen biosynthetic enzyme, aromatase, and systemic changes that have been linked to the pathogenesis of breast cancer. Here, we determined whether metabolic obesity, including changes in breast biology and systemic effects, occurs in a subset of women with normal body mass index (BMI). Breast WAT and fasting blood were collected from 72 women with normal BMI (<25 kg/m²) undergoing mastectomy for breast cancer risk reduction or treatment. WAT inflammation was defined by the presence of crown-like structures of the breast (CLS-B) which are composed of dead or dying adipocytes surrounded by macrophages. Severity of inflammation was measured as CLS-B/cm² The primary objective was to determine whether breast WAT inflammation is associated with aromatase expression and activity. Secondary objectives included assessment of circulating factors and breast adipocyte size. Breast WAT inflammation was present in 39% of women. Median BMI was 23.0 kg/m² (range, 18.4-24.9 kg/m²) in women with breast WAT inflammation versus 21.8 kg/m² (range, 17.3-24.6 kg/m²) in those without inflammation (P = 0.04). Breast WAT inflammation was associated with elevated aromatase expression and activity, which increased with severity of inflammation (P < 0.05). Breast WAT inflammation correlated with larger adipocytes (P = 0.01) and higher circulating levels of C-reactive protein, leptin, insulin, and triglycerides (P ≤ 0.05). A subclinical inflammatory state associated with elevated aromatase in the breast, adipocyte hypertrophy, and systemic metabolic dysfunction occurs in some normal BMI women and may contribute to the pathogenesis of breast cancer. Cancer Prev Res; 10(4); 235-43. ©2017 AACRSee related article by Berger, p. 223-25.

Preliminary results from a single-arm, phase II study assessing the efficacy of pembrolizumab plus radiotherapy in metastatic triple negative breast cancer

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Background: Two trials have demonstrated overall response rates of 19% with immune checkpoint inhibitors alone in chemotherapy-resistant triple negative breast cancer (TNBC). Radiation therapy (RT) is frequently used to enhance local control in TNBC and has been reported to induce distant (abscopal) tumor responses when combined with immunotherapy. We evaluate the safety and efficacy of the combination of RT and pembrolizumab, a programmed cell death protein 1 (PD-1) inhibitor, in a single-arm, two-stage, phase II study in metastatic TNBC. Results from the first stage are reported. Methods: Eligibility criteria includes women with biopsy-proven TNBC, ECOG performance status 0-2, ≥ 2 measurable sites of metastatic disease with at least one site requiring RT. A total RT dose of 3000 cGy is delivered in one week in 5 fractions. Pembrolizumab is given intravenously at 200 mg/kg D1+/- 3 days and then every 3 weeks until disease progression as defined by RECIST v 1.1. The primary endpoint is overall response rate at week 13 in the non-targeted, non-irradiated lesions. Secondary endpoints include safety and overall survival. Tumor biopsies are obtained at baseline and at week 7. PD-L1 expression was not required for study entry. Results: Nine patients were enrolled in the first phase and assessed for antitumor activity and safety. Median age was 52 years (range 37-73). Three patients died secondary to disease-related complications (at weeks 2, 6 and 8) and 1 came off study due to disease progression prior to week 13. Of the 5 patients evaluable at week 13, 2 had a partial response, 1 had stable disease and 2 had disease progression. Common toxicities were mild and included fatigue, myalgia and nausea. One grade 3 event was reported - hyperbilirubinemia not attributable to study therapy after one dose of pembrolizumab. Conclusions: The combination of pembrolizumab and RT was well-tolerated in the first stage of a phase II study. Responses were observed outside of the RT fields in 2 of 5 patients who were evaluable at 13 weeks. The contribution of RT to pembrolizumab is unknown and will be investigated in the second stage of the study, which is ongoing. Correlative studies are planned. Clinical trial information: NCT02730130.

Perinephric white adipose tissue inflammation in clear cell renal cell carcinoma (ccRCC)

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Background: High body mass index (BMI) is an established risk factor for developing ccRCC but is associated with better survival in clinical studies. The obesity paradox may be influenced by metabolically healthy patients classified as obese, and metabolically unhealthy patients classified as normal weight. We evaluated white adipose tissue inflammation (WATi) in perinephric fat as a new marker of metabolic dysregulation and examined its association with clinicopathological characteristics. Methods: In July 2015, we established a prospective cohort study at Memorial Sloan Kettering Cancer Center to investigate the prognostic significance of perinephric WATi among patients undergoing nephrectomy. Perinephric WAT is collected during surgery and patients are followed for clinical outcomes. WATi is defined by the presence of dead/dying adipocytes surrounded by macrophages forming crown-like structures (CLS) and detected through immunohistochemistry. Clinicopathological data are abstracted from the electronic medical record. Wilcoxon rank-sum, Chi-square, or Fisher’s exact tests describe the relationship between CLS status and clinicopathological characteristics on the first 38 ccRCC patients. Results: The study cohort had a median age of 56 years (range 47-64 years) and was predominantly male (71%). CLS were detected in 50% of patients, did not differ by age or sex, and were present in all BMI levels; 59% of obese, 38.5% of overweight, and 33% of normal weight patients (p = 0.47). CLS was significantly associated with advanced disease characteristics including higher stage (p = 0.03) and local invasion (p = 0.02). Median tumor size was larger in patients who were CLS+ (3.5 cm, range 2.65-5.75) than CLS- (2.2 cm, range 1.55-3.00; p = 0.02). Conclusions: Perinephric WATi was found in ccRCC patients of all BMI levels and associated with factors related to poor prognosis. Patients with occult inflammation may be at higher mortality risk, regardless of their BMI. Recruitment of additional cases and analyses to examine how CLS influences ccRCC survival are on-going.

Incidence of periprostatic white adipose tissue inflammation in men with prostate cancer

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Background: Obesity, a common cause of chronic inflammation, is associated with an increased risk of high grade, lethal prostate cancer (PC) and poor outcomes. The existence or clinical importance of periprostatic white adipose tissue inflammation (WATi) in patients (pts) with PC has not been previously described. We examined the relationships among periprostatic WATi and 1) tumor clinicopathologic features, and 2) host factors including age, body mass index (BMI), and circulating metabolic factors. Methods: Periprostatic WAT was collected prospectively from men with PC undergoing radical prostatectomy. WATi was defined by the presence of dead/dying adipocytes surrounded by macrophages forming crown-like structures (CLS). Tumor characteristics and host factors were measured. Wilcoxon rank-sum, Chi-square, or Fisher’s exact tests were used to examine the relationship between WATi and tumor and host characteristics. Results: From 11/2011-8/2015, periprostatic WAT was obtained from 169 pts (median age 62 years, range: 39 -77). Fasting blood samples were collected from 154 pts. CLS were present in 84 (49.7%) of pts. Presence of CLS was associated with higher median BMI (P = 0.02); 40/65 (61.5%) obese pts, 36/83 (43.4 %) overweight pts, and 8/21 (38.1 %) normal weight pts had CLS. Pts with CLS were more likely to have high grade prostate cancer (Gleason grade group IV/V, P = 0.02), larger adipocytes (P = 0.004), and positive surgical margins at the time of surgery (P = 0.04). WATi correlated with higher circulating levels of insulin, triglycerides, and leptin/adiponectin ratio, and lower high density lipoprotein cholesterol, compared to pts without WATi (P’s < 0.05). Conclusions: Periprostatic WATi is common in men with PC. It is associated with high grade PC and alterations in systemic factors that contribute to PC development and progression. Periprostatic WATi may represent a therapeutic target for improving PC risk and outcomes.

Abstract P4-21-34: Phase II study of gemcitabine, trastuzumab, and pertuzumab for HER2-Positive metastatic breast cancer after prior pertuzumab-based therapy

Background: The combination of taxanes with trastuzumab (H) and pertuzumab (P) for first line treatment of HER2-positive metastatic breast cancer (MBC) is associated with improved progression-free survival (PFS) and overall survival (OS). Treatment per physician's choice with anti-HER2 therapy after second line therapy is associated with a median PFS of 3 months. While continued use of H in therapeutic combinations after progression on H-based therapy is common, the efficacy of continuing HP-based treatment after progression on P-based therapy is unknown.

Methods: This is a single arm phase II trial of gemcitabine (G) with HP. Eligible patients had HER2-positive (IHC 3+ or FISH ≥ 2.0) MBC with prior HP-based treatment and ≤ 3 prior chemotherapies. Patients received G (1200 mg/m2) on days 1 and 8 of a q 3 week (w) cycle, and H (8 mg/kg load → 6 mg/kg) and P (840 mg load → 420 mg) q3w. The primary endpoint is PFS at 3 months. Secondary endpoints include OS, safety and tolerability. An exploratory endpoint is to compare PFS by RECIST criteria versus 18-F FDG-PET response criteria. Using a Simon optimal 2-stage design, 21 patients were enrolled in stage 1. The successful 3-month PFS rate for stage 1 was set at 57% to allow accrual to stage 2 for a total of 45 patients. The study therapy will be considered successful if at least 27/45 (60%) patients are progression free at 3 months.

Results: As of June 9, 2016, 28 patients are enrolled; 21 are evaluable at 3 months and 7 have not had 3-month evaluation. At 3 months, 16/21 (76%) are progression free; 5 patients have progressed. The 3 month-PFS results for evaluable patients will be updated. There are no cardiac or febrile neutropenic events to date. Initially, 5 of 22 (23%) patients required G dose reduction (4 due to grade 3 neutropenia and 1 due to grade 3 vomiting) and the study was amended to lower initial G dose to 1000 mg/m2.

Conclusions: The preliminary 3 month-PFS is 76% (95% CI 55% to 89%) in evaluable patients, and updated data will be presented. These findings suggest clinical benefit when P is continued beyond progression.

Citation Format: Iyengar NM, Smyth L, Lake D, Gucalp A, Singh JC, Traina TA, DeFusco P, Dickler MN, Fornier MN, Goldfarb S, Jhaveri K, Modi S, Troso-Sandoval T, Argolo D, Jack K, Ulaner G, Jochelson M, Baselga J, Norton L, Hudis CA, Dang CT. Phase II study of gemcitabine, trastuzumab, and pertuzumab for HER2-Positive metastatic breast cancer after prior pertuzumab-based therapy [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P4-21-34.

Abstract PD5-05: Metabolic obesity, adipose inflammation and aromatase: Potential drivers of breast cancer risk in women with normal body mass index

Background: Elevated body mass index (BMI) is associated with increased risk of postmenopausal breast cancer, which may be partly attributable to an inflammation-aromatase axis. Most individuals with elevated BMI harbor white adipose tissue inflammation (WATi), defined by the presence of crown-like structures in the breast (CLS-B). CLS-B are composed of a dead/dying adipocyte surrounded by CD68+ macrophages. This inflammation is associated with activation of NF-κB and elevated expression of aromatase, which could contribute to tumor development. Additionally, WATi correlates with several circulating changes, including hyperinsulinemia, which increase breast cancer risk. Although breast WATi correlates with rising BMI, it is also present in some normal BMI individuals. Beyond inherited germline syndromes, the etiology of breast cancer in individuals with normal BMI is not well understood. Here we examined the impact of breast WATi on breast aromatase expression and circulating factors in women with normal BMI.

Methods: Non-tumorous breast tissue and fasting blood were collected from 72 women with BMI &lt; 25 kg/m2 undergoing mastectomy at MSKCC. Breast inflammation was detected by the presence of CLS-B using CD68 immunohistochemistry. The primary objective was to determine if breast WATi in normal BMI individuals correlates with elevated aromatase levels in the breast, measured by qPCR, western blotting, immunofluorescence and enzyme activity. Secondary objectives included assessment of breast adipocyte size and circulating metabolic and inflammatory factors.

Results: Breast inflammation was present in 39% of women. Median BMI was 23.0 (range 18.4 to 24.9) in women with breast WATi versus 21.8 (range 17.3 to 24.6) in those without inflammation (P=0.04). Aromatase mRNA expression was positively correlated with WATi (CLS-B/cm2; P=0.002). Those with severe WATi had highest aromatase mRNA levels, compared to those with no or mild WATi (P=0.005). Aromatase protein, assessed by measuring adipose stromal cell-specific immunofluorescence or western blotting, and activity were also higher in CLS-B+ cases compared to CLS-B- (P&lt;0.001). Breast WATi correlated with larger adipocytes (P=0.01) and higher circulating levels of C-reactive protein, leptin, insulin, and triglycerides (P&lt;0.05). Insulin resistance, characterized by the homeostasis model (HOMA2-IR), correlated with breast WATi (P=0.004). Finally, leptin, a known inducer of aromatase and driver of cancer growth, correlated with higher breast aromatase levels (P=0.02) and larger adipocytes (P&lt;0.01).

Conclusions: A metabolically unhealthy state occurs in women with inflamed breast adipose despite having a normal BMI. This subclinical inflammatory state is characterized by elevated aromatase in the breast, insulin resistance, and dysplipidemia. The presence of enlarged adipocytes in the breasts of normal BMI women with inflammation suggests a state of hyperadiposity which could not be predicted based on BMI alone. These findings indicate that normal BMI metabolic obesity may be associated with increased cancer risk. Our results suggest that objective measurements of adiposity rather than BMI may help to identify individuals at increased risk for disease.

Citation Format: Iyengar NM, Brown KA, Zhou XK, Subbaramaiah K, Giri DD, Gucalp A, Howe LR, Zahid H, Bhardwaj P, Wendel NK, Falcone DJ, Morrow M, Wang H, Williams S, Pollak M, Hudis CA, Dannenberg AJ. Metabolic obesity, adipose inflammation and aromatase: Potential drivers of breast cancer risk in women with normal body mass index [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr PD5-05.

Abstract P2-08-05: Phase I/II trial of palbociclib in combination with bicalutamide for the treatment of androgen receptor (AR)+ metastatic breast cancer (MBC)

This abstract was withdrawn by the authors.

Obesity and Cancer Mechanisms: Tumor Microenvironment and Inflammation

Purpose There is growing evidence that inflammation is a central and reversible mechanism through which obesity promotes cancer risk and progression. Methods We review recent findings regarding obesity-associated alterations in the microenvironment and the local and systemic mechanisms through which these changes support tumor growth. Results Locally, hyperadiposity is associated with altered adipose tissue function, adipocyte death, and chronic low-grade inflammation. Most individuals who are obese harbor inflamed adipose tissue, which resembles chronically injured tissue, with immune cell infiltration and remodeling. Within this distinctly altered local environment, several pathophysiologic changes are found that may promote breast and other cancers. Consistently, adipose tissue inflammation is associated with a worse prognosis in patients with breast and tongue cancers. Systemically, the metabolic syndrome, including dyslipidemia and insulin resistance, occurs in the setting of adipose inflammation and operates in concert with local mechanisms to sustain the inflamed microenvironment and promote tumor growth. Importantly, adipose inflammation and its protumor consequences can be found in some individuals who are not considered to be obese or overweight by body mass index. Conclusion The tumor-promoting effects of obesity occur at the local level via adipose inflammation and associated alterations in the microenvironment, as well as systemically via circulating metabolic and inflammatory mediators associated with adipose inflammation. Accurately characterizing the obese state and identifying patients at increased risk for cancer development and progression will likely require more precise assessments than body mass index alone. Biomarkers of adipose tissue inflammation would help to identify high-risk populations. Moreover, adipose inflammation is a reversible process and represents a novel therapeutic target that warrants further study to break the obesity-cancer link.

Targeting the androgen receptor in triple-negative breast cancer

Triple-negative breast cancer represents approximately 15%-20% of all newly diagnosed breast cancers, but it accounts for a disproportionate number of breast cancer-related deaths each year. Owing to the lack of estrogen, progesterone, and human epidermal growth factor receptor 2 expression, patients with triple-negative breast cancer do not benefit from generally well-tolerated and effective therapies targeting the estrogen and human epidermal growth factor receptor 2 signaling pathways and are faced with an increased risk of disease progression and poorer overall survival. The heterogeneity of triple-negative breast cancer has been increasingly recognized and this may lead to therapeutic opportunities because of newly defined oncogenic drivers and targets. A subset of triple-negative breast tumors expresses the androgen receptor (AR) and this may benefit from treatments that inhibit the AR-signaling pathway. The first proof-of-concept trial established activity of the AR antagonist, bicalutamide, in patients with advanced AR+ triple-negative breast cancer. Since that time, evidence further supports the activity of other next-generation AR-targeted agents such as enzalutamide. Not unlike in estrogen receptor-positive breast cancer, mechanisms of resistance are being investigated and rationale exists for thoughtful, well-designed combination regimens such as AR antagonism with CDK4/6 pathway inhibitors or PI3K inhibitors. Furthermore, novel agents developed for the treatment of prostate cancer, which reduce androgen production such as abiraterone acetate and seviteronel, are being tested as well. This review summarizes the underlying biology of AR signaling in breast cancer development and the available clinical trial data for the use of anti-androgen therapy in the treatment of AR+ triple-negative breast cancer.