Mosunetuzumab Consolidation Therapy After autoSCT in r/r Aggressive B Cell Lymphoma

Inclusion Criteria for Screening Pre-autoSCT: * Diagnosis of rCD20+ large B cell lymphoma, high-grade B cell lymphoma, transformed B cell lymphoma, primary mediastinal B cell lymphoma, or follicular lymphoma grade 3B. * Planning to undergo autologous stem cell transplantation after two or more prior lines of therapy for lymphoma, including treatment for prior/underlying indolent B-NHL. * At least 18 years of age. * ECOG performance status ≤ 2 * The effects of mosunetuzumab on the developing human fetus are unknown. For this reason, women of childbearing potential and men must agree to use adequate contraception prior to study entry, for the duration of study treatment, and for 3 months following the final dose of mosunetuzumab. Specifically, women must remain abstinent or use contraceptive methods with a failure rate of \<1% per year during the treatment period and for 3 months after the final dose of mosunetuzumab as applicable. Should a woman become pregnant or suspect she is pregnant while participating in this study, she must inform her treating physician immediately. Men treated or enrolled on this protocol with a female partner of childbearing potential or pregnant female partner must also agree to use adequate contraception prior to the study, for the duration of study treatment, and for 3 months following the final dose of mosunetuzumab. * Ability to understand and willingness to sign an IRB approved written informed consent document. Exclusion Criteria for Screenin…