Phase I/II trial of palbociclib, pembrolizumab and letrozole in patients with hormone receptor-positive metastatic breast cancer.

BACKGROUND: CDK4/6 inhibitors modulate immune response in breast cancer. This phase I/II trial was designed to test the safety and efficacy of palbociclib, pembrolizumab and letrozole in women with hormone receptor positive (HR+) human epidermal growth factor receptor 2 negative (HER2-) metastatic breast cancer (MBC). PATIENTS AND METHODS: Women with stage IV HR+ HER2- MBC were enrolled and treated with palbociclib, pembrolizumab and letrozole. Primary end-points were safety, tolerability and efficacy. RESULTS: Between November 2016 and July 2020, 23 patients were enrolled with 20 evaluable for response, including 4 patients in cohort 1 and 16 patients in cohort 2. Cohort 1 median age was 48 years (33-70) and cohort 2 median age was 55 (37-75). Cohort 1 closed early due to limited accrual. Grade III-IV adverse events were neutropenia (83%), leucopaenia (65%), thrombocytopenia (17%) and elevated liver enzymes (17%). In cohort 1, 50% achieved a partial response (PR) and 50% had stable disease (SD). In cohort 2, 31% achieved complete response (CR), 25% had PR and 31% had SD by Response Evaluation Criteria in Solid Tumours version 1.1. Median progression-free survival was 25.2 months (95% confidence interval [CI] 5.3, not reached) and median overall survival was 36.9 months (95% CI 36.9, not reached) in cohort 2 with a median follow-up of 24.8 months (95% CI 17.1, not reached). A correlative immune biomarker analysis was published separately. CONCLUSION: The combination of palbociclib, pembrolizumab and letrozole is well tolerated, and a complete response rate of 31% was identified in HR+ MBC patients who received this combination as front-line therapy. Confirmatory trials are required to better understand the immune-priming effects of CDK4/6 inhibitors.

Characteristics Associated With Functional Changes During Systemic Cancer Treatments: A Systematic Review Focused on Older Adults.

BACKGROUND: Maintaining functional status is important to older adults with cancer, but data are limited on how systemic treatments affect functional status. We systematically reviewed changes in functional status during systemic cancer treatments and identified characteristics associated with functional decline and improvement. METHODS: We searched PubMed, Embase, Web of Science, and Cochrane Register of Controlled Trials for articles examining characteristics associated with functional changes in older adults during systemic cancer treatment published in English between database inception and January 11, 2019 (PROSPERO CRD42019123125). Findings were summarized with descriptive statistics. Study characteristics between older adult-specific and non-older adult-specific studies were compared using the Fisher exact test. RESULTS: We screened 15,244 titles/abstracts and 519 full texts. The final analysis included 44 studies, which enrolled >8,400 patients; 39% of studies focused on older adults (1 study enrolled adults aged ≥60 years, 10 enrolled adults aged ≥65 years, and 6 enrolled adults aged ≥70 years). Almost all studies (98%) used patient-reported outcomes to measure functional status; only 20% used physical performance tests. Reporting of functional change was heterogeneous, with 48% reporting change scores. Older adult-specific studies were more likely to analyze functional change dichotomously (29% vs 4%; P=.008). Functional decline ranged widely, from 6% to 90%. The most common patient characteristics associated with functional decline were older age (n=7 studies), worse performance status (n=4), progressive disease status (n=4), pain (n=4), anemia (n=4), and worse nutritional status (n=4). Twelve studies examined functional improvement and identified 11 unique associated characteristics. CONCLUSIONS: Functional decline is increasingly recognized as an important outcome in older adults with cancer, but definitions and analyses are heterogeneous, leading to a wide range of prevalence. To identify patients at highest risk of functional decline during systemic cancer treatments, trials need to routinely analyze functional outcomes and measure characteristics associated with decline (eg, nutrition).

Phase II study of neratinib in older adults with HER2 amplified or HER2/3 mutated metastatic breast cancer.

OBJECTIVE: The tolerability and efficacy of targeted therapy in older adults with cancer has not been adequately studied. Neratinib is a novel HER1, HER2, HER4 tyrosine kinase inhibitor that has recently been granted FDA approval for treatment of breast cancer. The major toxicity of neratinib is diarrhea, which affects up to 90% of patients. This phase II trial evaluates the safety and tolerability of neratinib in adults ≥60. METHODS: Patients aged 60 or older with histologically proven metastatic breast cancer and HER2 amplification (defined by ASCO/CAP guideline) or HER2/HER3 activating mutation were enrolled to receive neratinib at 240 mg daily in 28-day cycles. The association between tolerability, defined as dose reduction and number of completed courses, and log2 Cancer and Aging Research Group (CARG) toxicity risk score was assessed using a Student's t-test and linear regression, respectively. Response rate, progression free survival, and overall survival were also evaluated. RESULTS: 25 patients were enrolled with median age of 66 (range 60-79). Seventy-six percent of patients were white, 16% Asian, and 8% African-American. Seventy-six percent were patients with hormone receptor (HR) positive metastatic breast cancer (MBC) and 24% were patients with HR negative MBC. Median number of prior lines of metastatic therapy were 3 (range 0-11). 20/25 (80%) had worst grade toxicities ≥2. A total of 9/25 (36%) had grade 3 toxicities including 5/20 (20%) diarrhea, 2/20 (8%) vomiting, and 2/20 (8%) abdominal pain. There were no grade 4 or 5 toxicities. A total of 9/25 (36%) had dose reduction, and 2/25 (8%) discontinued therapy due to toxicity. The association between dose reductions and CARG toxicity score reached borderline statistical significance suggesting a trend with participants with higher CARG toxicity risk scores being more likely to require a dose modification (p = 0.054). 1/25 (4%) had a partial response, 11/25 (44%) had stable disease, 12/25 (48%) had progression of disease, and 1/25 (4%) was not assessed. Median progression free survival (PFS) was 2.6 months (95% CI [2.56-5.26]), and median overall survival (OS) was 17.4 months (95% CI [10.3, NA]). CONCLUSIONS: Neratinib was safe in this population of older adults with HER2 amplified or HER2/3 mutated metastatic breast cancer (BC). Higher CARG toxicity risk score may be associated with greater need for dose adjustments. Future studies are needed to confirm this finding.

Older adult participation in cancer clinical trials: A systematic review of barriers and interventions.

Cancer is a disease of aging and, as the world's population ages, the number of older persons with cancer is increasing and will make up a growing share of the oncology population in virtually every country. Despite this, older patients remain vastly underrepresented in research that sets the standards for cancer treatments. Consequently, most of what we know about cancer therapeutics is based on clinical trials conducted in younger, healthier patients, and effective strategies to improve clinical trial participation of older adults with cancer remain sparse. For this systematic review, the authors evaluated published studies regarding barriers to participation and interventions to improve participation of older adults in cancer trials. The quality of the available evidence was low and, despite a literature describing multifaceted barriers, only one intervention study aimed to increase enrollment of older adults in trials. The findings starkly amplify the paucity of evidence-based, effective strategies to improve participation of this underrepresented population in cancer trials. Within these limitations, the authors provide their opinion on how the current cancer research infrastructure must be modified to accommodate the needs of older patients. Several underused solutions are offered to expand clinical trials to include older adults with cancer. However, as currently constructed, these recommendations alone will not solve the evidence gap in geriatric oncology, and efforts are needed to meet older and frail adults where they are by expanding clinical trials designed specifically for this population and leveraging real-world data.

A Phase II Clinical Trial of Pembrolizumab and Enobosarm in Patients with Androgen Receptor-Positive Metastatic Triple-Negative Breast Cancer.

LESSONS LEARNED: The combination of enobosarm and pembrolizumab was well tolerated and showed a modest clinical benefit rate of 25% at 16 weeks. Future trials investigating androgen receptor-targeted therapy in combination with immune checkpoint inhibitors are warranted. BACKGROUND: Luminal androgen receptor is a distinct molecular subtype of triple-negative breast cancer (TNBC) defined by overexpression of androgen receptor (AR). AR-targeted therapy has shown modest activity in AR-positive (AR+) TNBC. Enobosarm (GTx-024) is a nonsteroidal selective androgen receptor modulator (SARM) that demonstrates preclinical and clinical activity in AR+ breast cancer. The current study was designed to explore the safety and efficacy of the combination of enobosarm and pembrolizumab in patients with AR+ metastatic TNBC (mTNBC). METHODS: This study was an open-label phase II study for AR+ (≥10%, 1+ by immunohistochemistry [IHC]) mTNBC. Eligible patients received pembrolizumab 200 mg intravenous (IV) every 3 weeks and enobosarm 18 mg oral daily. The primary objective was to evaluate the safety of enobosarm plus pembrolizumab and determine the response rate. Peripheral blood, tumor biopsies, and stool samples were collected for correlative analysis. RESULTS: The trial was stopped early because of the withdrawal of GTx-024 drug supply. Eighteen patients were enrolled, and 16 were evaluable for responses. Median age was 64 (range 36-81) years. The combination was well tolerated, with only a few grade 3 adverse events: one dry skin, one diarrhea, and one musculoskeletal ache. The responses were 1 of 16 (6%) complete response (CR), 1 of 16 (6%) partial response (PR), 2 of 16 (13%) stable disease (SD), and 12 of 16 (75%) progressive disease (PD). Response rate (RR) was 2 of 16 (13%). Clinical benefit rate (CBR) at 16 weeks was 4 of 16 (25%). Median follow-up was 24.9 months (95% confidence interval [CI], 17.5-30.9). Progression-free survival (PFS) was 2.6 months (95% CI, 1.9-3.1) and overall survival (OS) was 25.5 months (95% CI, 10.4-not reached [NR]). CONCLUSION: The combination of enobosarm and pembrolizumab was well tolerated, with a modest clinical benefit rate of 25% at 16 weeks in heavily pretreated AR+ TNBC without preselected programmed death ligand-1 (PD-L1). Future clinical trials combining AR-targeted therapy with immune checkpoint inhibitor (ICI) for AR+ TNBC warrant investigation.

Strategies to Improve Participation of Older Adults in Cancer Research.

Cancer is a disease associated with aging. As the US population ages, the number of older adults with cancer is projected to dramatically increase. Despite this, older adults remain vastly underrepresented in research that sets the standards for cancer treatments and, consequently, clinicians struggle with how to interpret data from clinical trials and apply them to older adults in practice. A combination of system, clinician, and patient barriers bar opportunities for trial participation for many older patients, and strategies are needed to address these barriers at multiple fronts, five of which are offered here. This review highlights the need to (1) broaden eligibility criteria, (2) measure relevant end points, (3) expand standard trial designs, (4) increase resources (e.g., institutional support, interdisciplinary care, and telehealth), and (5) develop targeted interventions (e.g., behavioral interventions to promote patient enrollment). Implementing these solutions requires a substantial investment in engaging and collaborating with community-based practices, where the majority of older patients with cancer receive their care. Multifaceted strategies are needed to ensure that older patients with cancer, across diverse healthcare settings, receive the highest-quality, evidence-based care.

Barriers to Participation in Therapeutic Clinical Trials as Perceived by Community Oncologists.

PURPOSE: Despite considerable research on the barriers to enrollment in cancer therapeutic trials, few studies have elicited barriers from the perspective of community physicians, who provide the majority of cancer care. The purpose of this study was to characterize barriers to and facilitators of cancer therapeutic trials as perceived by oncologists in community practices. METHODS: Twenty semistructured interviews were conducted with oncologists at six community sites affiliated with City of Hope National Medical Center from March to June 2018. Responses were recorded digitally and transcribed. Data were analyzed using qualitative content analysis. RESULTS: Of the 20 participants, 4 (20%) were women, 13 (65%) had > 10 years of practice experience, and 16 (80%) reported that < 5% of their patients were enrolled in a therapeutic trial. Participants identified four system-level barriers: lack of appropriate trials for community-based settings, insufficient infrastructure support, restrictive eligibility criteria, and financial limitations; three physician-level barriers: lack of awareness of available trials, lack of knowledge of trial details, and lack of time; and two patient-level barriers: patient burden and negative beliefs/attitudes toward research. Efforts aimed to increase trial availability, clinical trial support personnel, and physician knowledge were identified as major facilitators. CONCLUSION: Community oncologists face numerous complex, multifaceted barriers to cancer therapeutic trial enrollment. Although expanding clinical research beyond the academic setting allows access to a larger and more diverse patient population, increasing generalizability and relevance of trial findings, there remains a substantial need for new strategies to improve cancer research delivery in the community.

Barriers to clinical trial enrollment of older adults with cancer: A qualitative study of the perceptions of community and academic oncologists.

OBJECTIVES: Oncologists can be one of the major barriers to older adult's participation in research. Multiple studies have described academic clinicians' concerns for not enrolling older adults onto trials. Although the majority of older adults receive their cancer care in the community, few studies have examined the unique challenges that community oncologists face and how they differ from oncologist-related barriers in academia. METHODS: Semi-structured interviews were conducted by telephone or face-to-face with 44 medical oncologists (24 academic-based and 20 community-based) at City of Hope from March to June 2018. Interviews explored oncologists' perceptions of barriers to clinical trial enrollment of older adults with cancer. Data were analyzed using qualitative content analysis. RESULTS: Of the 44 participants, 36% were women and 68% were in practice for >10 years. Among the entire sample, stringent eligibility criteria (n = 20) and oncologist concerns for treatment toxicities (n = 15) were the most commonly cited barriers. Compared to academic oncologists, community oncologists more often cited patient attitudes, beliefs, and understanding (n = 9 vs. n = 2) and caregiver burden (n = 6 vs. n = 0). In contrast, compared to community oncologists, academic oncologists more often cited oncologist bias (n = 10 vs. n = 3) and insufficient time/support (n = 4 vs. n = 1). CONCLUSIONS: Differences in perceptions among academic and community oncologists about trials suggest that barriers are multifaceted, complex, and vary by practice setting. Interventions to increase trial accrual among older adults with cancer may benefit from being tailored to address the unique barriers of different practice settings.