Study to Evaluate the Safety and Efficacy of a Combination of MK-4280 and Pembrolizumab (MK-3475) in Participants With Hematologic Malignancies (MK-4280-003)

Open to people ages 18 years and up

• Has measureable disease, defined as ≥1 lesion that can be accurately measured in 2 dimensions with diagnostic quality cross sectional anatomic imaging (computed tomography or magnetic resonance imaging). Minimum measurement must be >15 mm in the longest diameter or >10 mm in the short axis
• Is able to provide a core or excisional tumor biopsy for biomarker analysis from an archival (within 3 months) or newly obtained biopsy at screening
• Has a performance status of 0 or 1 on the Eastern Cooperative Oncology Group (ECOG)

• Has known clinically active central nervous system (CNS) involvement
• Has received prior therapy with an anti-lymphocyte activation gene-3 (LAG-3) antibody
• Has received chimeric antigen receptors (CAR)-T-cell therapy
• Has received prior anticancer therapy or thoracic radiation therapy within 14 days before the first dose of study treatment
• Has ≥Grade 2 non-hematological toxicities from prior therapy
• Has had a prior anticancer monoclonal antibody within 4 weeks prior to study Day 1 or who has not recovered (i.e., ≤Grade 1 or at baseline) from AEs due to agents administered ≥4 weeks earlier
• Has received a live vaccine within 30 days prior to first dose of study treatment
• Is currently participating and receiving study therapy or has participated in a study of an investigational agent and received study therapy or used an investigational device within 28 days before study Day 1
• Has a diagnosis of immunodeficiency or is receiving chronic systemic steroid therapy or any other form of immunosuppressive therapy within 7 days prior the first dose of study drug
• Has a known additional malignancy that is progressing or requires active treatment with the exception of basal cell carcinoma of the skin, squamous cell carcinoma of the skin, or in situ cervical cancer that has undergone potentially curative therapy
• Has active autoimmune disease that has required systemic treatment in past 2 years (i.e., with use of disease modifying agents, corticosteroids or immunosuppressive drugs)
• Has a history of (non-infectious) pneumonitis that required steroids or current pneumonitis
• Has an active infection requiring intravenous systemic therapy
• Has a known history of human immunodeficiency virus (HIV) infection
• Has known, active hepatitis B or hepatitis C infection
• Is pregnant or breastfeeding, or expecting to conceive or father children within the projected duration of the study, starting with the screening visit through 120 days after the last dose of study treatment
• Has had an allogeneic hematopoetic stem cell/solid organ transplantation within the last 5 years