Epcoritamab for the Treatment of Relapsed or Refractory Post Transplant Lymphoproliferative Disorders

This phase Ib trial tests the safety and effectiveness of epcoritamab in treating patients with post-transplant lymphoproliferative disorder (PTLD) that has come back after a period of improvement (relapsed) or has not responded to previous treatment (refractory). Epcoritamab, a bispecific antibody, binds to a protein called CD3, which is found on T cells (a type of white blood cell). It also binds to a protein called CD20, which is found on B cells (another type of white blood cell) and some lymphoma cells. This may help the immune system kill cancer cells. Giving epcoritamab may be safe and effective in treating patients with relapsed or refractory B-cell PTLD.

PRIMARY OBJECTIVE: I. To assess the safety of treatment with epcoritamab in subjects with PTLD. SECONDARY OBJECTIVES: I. To estimate the Objective Response Rate (ORR), defined as the clinical response (complete response \[CR\] + partial response \[PR\]) after 3 cycles of epcoritamab. II. To estimate the clinical benefit rate (CBR) in subjects with PTLD treated with epcoritamab. III. To estimate the best objective response rate (BOR) in subjects with PTLD treated with epcoritamab. IV. To estimate the progression free survival (PFS) in subjects with PTLD treated with epcoritamab. V. To estimate the duration of complete response (DoCR) in subjects with PTLD treated with epcoritamab. VI. To estimate the overall survival (OS) in subjects with PTLD treated with epcoritamab. EXPLORATORY OBJECTIVES: I. To characterize the peripheral immunophenotype changes through the course of treatment with epcoritamab in subjects with PTLD. II. To describe the relationship of tumor microenvironment characteristics with clinical response to epcoritamab in subjects with PTLD. III. To characterize Epstein-Barr virus (EBV) methylation alterations in EBV positive PTLDs treated with epcoritamab IV. To describe the relationship between metabolic tumor volume and response to epcoritamab in subjects with PTLD. OUTLINE: This is a dose-escalation study of epcoritamab followed by a dose-expansion study. Patients receive epcoritamab subcutaneously (SC) on days 1, 8, 15, and 22 of cycles 1 and 2, days 1 and 15 of cycles 4-9, and day 1 of each subsequent cycle. Cycles repeat every 28 days for up to 12 cycles in the absence of disease progression or unacceptable toxicity. Patients with CR may continue to receive epcoritamab if disease progression occurs within 6 months. Patients with PR or stable disease (SD) continue to receive epcoritamab in the absence of disease progression or unacceptable toxicity. Patients also undergo positron emission tomography (PET)/computed tomography (CT) and blood sample collection throughout the study and may undergo biopsy during screening. After completion of study treatment, patients are followed up at 28 days and then every 3 months for up to 3 years.