Abexinostat in Combination With Pembrolizumab in Patients With Advanced Solid Tumor Malignancies

PRIMARY OBJECTIVES: I. To determine the maximally tolerated and recommended phase 2 dose of abexinostat in combination with anti-PD-1/PD-L1 checkpoint inhibitor (CPI). (Dose escalation) II. To determine the objective response rate (ORR) by Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 criteria in patients treated with abexinostat in combination with CPI in patients with prior primary (cohort A) or acquired (cohort B) resistance to prior CPI treatment. (Dose expansion) SECONDARY OBJECTIVES: I. To determine the objective response rate and median duration of response (DoR) by immune modified (i)RECIST criteria. II. To determine the median progression-free survival (PFS). III. To further characterize the safety profile of the treatment combination. OUTLINE: This is a dose-escalation study of abexinostat. Participants receive abexinostat orally (PO) twice daily (BID) on days 1-21 and pembrolizumab intravenously (IV) on over 30 minutes day 1. Courses repeat every 21 days in the absence of disease progression or unacceptable toxicity. After completion of study treatment, participants are followed up for 90 days.