Study to Evaluate the Safety and Preliminary Efficacy of Ibrutinib and Pembrolizumab in Patients With Chronic Lymphocytic Leukemia (CLL) or Mantle Cell Lymphoma (MCL)

The purpose of this study is to determine the most appropriate dose for the combination of ibrutinib and pembrolizumab and to see if the combination is active for the disease. The study will monitor for any side effects and if the combination of ibrutinib and pembrolizumab works in the cancers being studied. There will be 2 experimental drugs given to the subject in this study. One experimental drug used in this study is called ibrutinib and the second is called pembrolizumab. This is the first time that ibrutinib will be used in combination with pembrolizumab. This combination is considered experimental. Experimental means that it is still being tested to see if it is safe and effective. Ibrutinib is a new drug known as a 'Bruton's Tyrosine Kinase (BTK) inhibitor'. Ibrutinib blocks an enzyme (protein) that affects how certain types of blood cancer cells grow and survive. Blocking this enzyme is a very important mechanism in killing blood cancer cells. Ibrutinib has been approved in the United States, Israel, and the European Union for use in adult patients with mantle cell lymphoma (MCL) and adult patients with chronic lymphocytic leukemia (CLL) who have received at least one prior therapy. Pembrolizumab is an antibody (a type of human protein) that is being tested to see if it will allow the body's immune system to work against tumor cells. Pembrolizumab is approved for use by the U.S. Food and Drug Administration (FDA) for the treatment of adult patients with melanoma (skin cancer) who have received prior treatments. Pembrolizumab is not FDA approved to treat patients with chronic lymphocytic leukemia \[CLL\] and mantle cell lymphoma \[MCL\]. (1) Objective: a. (Phase 1) Assess the safety of fixed dose or, as needed, de-escalated ibrutinib/pembrolizumab in patients with MCL (Cohort A) and CLL (Cohort B) to determine recommended phase 2 dosing. b. (Phase 2A): Assess CR rate of combination ibrutinib/pembrolizumab therapy, in comparison to historical data of ibrutinib monotherapy, in patients with MCL (Cohort C) and CLL (Cohort D). Hypothesis: This is an open-label Phase 1/2A study, which consists of Phase 1 (Safety Assessment Cohorts) utilizing a 3+3 dose de-escalation design and Phase 2A (Expansion Cohorts) utilizing a single arm one-stage design. All patients receive a 28 day lead-in of ibrutinib and thereafter, a treatment 'cycle' is defined as a course of treatment of 21 days starting with the intravenous administration of pembrolizumab on Day 1 of each cycle along with once daily oral intake of ibrutinib on all days. 1. The combination of ibrutinib and pembrolizumab will be safe and well tolerated. 2. The combination of ibrutinib and pembrolizumab will result in higher CR rates compared to historic data of ibrutinib monotherapy in cohorts of CLL and MCL. Secondary Objectives \& Hypotheses (1) Objective: (Phase 2A): Assess duration of response, overall response rate, and duration of stable disease, compared to historical data of single agent ibrutinib, in patients with MCL (Cohort C) and CLL (Cohort D). Hypothesis: The combination of ibrutinib and pembrolizumab will increase duration of response, overall response rate and duration of stable disease when compared to historical data of single agent ibrutinib.