Testing the Anti-cancer Drug, Glofitamab, in Patients With Mantle Cell Lymphoma (A Type of Blood Cancer) Whose Disease Returned After CAR-T Cell Therapy

PRIMARY OBJECTIVE: I. To determine the proportion of relapsed/refractory (R/R) mantle cell lymphoma (MCL) patients with an objective response (OR) to glofitamab after prior treatment with chimeric antigen receptor (CAR)-T. SECONDARY OBJECTIVES: I. To describe the proportion of patients with a complete response (CR). II. To describe the progression-free survival (PFS) and overall survival (OS) at 24 months. III. To describe the incidence of grade 3-4 cytokine release syndrome (CRS). IV. To describe the incidence of grade 3-4 neurologic toxicity. V. To describe the relationship between glofitamab clearance at baseline, changes in clearance over time, treatment response, and duration of response. EXPLORATORY OBJECTIVES: I. To evaluate the relationship between circulating tumor deoxyribonucleic acid (DNA) (ctDNA) detection in plasma, treatment response, and duration of response. II. To evaluate the relationship between CAR T-cell levels in plasma, immunophenotype, treatment response, and duration of response. III. To evaluate the relationship between fluorodeoxyglucose positron emission tomography/ computed tomography (FDG PET/CT) interlesional treatment response heterogeneity and survival outcomes. IV. To evaluate the relationship between organ-specific changes in standardized uptake value (SUV) metrics and immune-related adverse events (AEs). OUTLINE: Patients receive obinutuzumab intravenously (IV) on day 1 or on days 1 and 2 of cycle 1 and glofitamab IV over 8 hours on days 8 and 15 of cycle 1 then over 2-8 hours on day 1 of cycles 2-12. Cycles repeat every 21 days for up to 12 cycles in the absence of disease progression or unacceptable toxicity. Additionally, patients undergo blood sample collection and PET/CT throughout the study. After completion of study treatment, patients are followed every 3 months for up to 2 years.