OBINUTUZUMAB THERAPY IN PATIENTS WITH MARGINAL ZONE AND MANTLE CELL LYMPHOMA (2019)

Introduction: Obinutuzumab (OBI) is FDA approved in chronic lymphocytic leukemia and follicular lymphoma, with favorable efficacy profiles noted in both settings. While there was a small subpopulation of marginal zone lymphoma (MZL) and mantle cell lymphoma patients (pts) in the GAUSS trial and GADOLIN/GAUGUIN trials respectively, there is little clinical experience in using OBI in these patient populations outside the context of a clinical trial. We describe a real world experience of OBI use in MZL and MCL pts off clinical trial. Methods: We conducted a retrospective cohort study of all adult pts who received OBI for MZL and MCL at the University of Pennsylvania between 2/2013 and 2/2019. Demographics, duration of therapy, reason for discontinuation, overall response, survival, and toxicities were examined. The primary endpoints were progression-free survival (PFS; defined as time from OBI start to disease progression or regimen change, death due to MZL/MCL or last-follow-up in remission), and overall survival using the Kaplan-Meier method. All other analyses were descriptive. Results: We identified a total of 10 pts for the entire cohort, 6 with MZL and 4 with MCL. The median age at start of OBI was 64 years (Range 50-92). 80% of pts were stage 4, had a median of 2 prior therapies (1 MZL patient treated frontline), median ECOG status 0, and one MZL patient had an MYD88 mutation. One patient was rituximab naïve, but 70% were rituximab refractory. The median number of cycles administered of OBI was 7 (Range 1-31) respectively. 50% of pts received OBI in combination, 3 pts with bendamustine, 1 with chlorambucil, and 1 with ibrutinib. Overall response rate was 90% (10% CR). Median PFS and OS were 11.5 and 13.5 months respectively. Two pts progressed following OBI therapy; one patient with MZL who subsequently was treated with ibrutinib and one with MCL subsequently treated with venetoclax. 50% of pts experienced at least one Adverse event(AE). AEs included: Infusion related reactions (40%), thrombocytopenia (40%), diarrhea (30%), neutropenia (20%), infection (10%). Three pts were on growth factor during OBI administration. One patient discontinued therapy secondarily to an infusion related reaction. Keywords: mantle cell lymphoma (MCL); marginal zone lymphoma (MZL); obinutuzumab. Disclosures: Hughes, M: Consultant Advisory Role: AstraZeneca; Research Funding: Acerta Pharma. Schuster, S: Consultant Advisory Role: Novartis, Nordic Nanovector, Celgene, Merck, Gilead, Pfizer; Honoraria: Genentech, Novartis, Nordic Nanovector, Celgene, Merck, OncLive, Dava Oncology, Physician's Education Source, LLC; Research Funding: Genentech, Novartis, Nordic Nanovector, Celgene, Merck, OncLive, Dava Oncology, Physician's Education Source, LLC. Svoboda, J: Consultant Advisory Role: BMS, Seattle Genetics, KITE, Kyowa, Pharmacyclics; Research Funding: BMS, Regeneron, Merck, Seattle Genetics, TG Therapeuitcs, Pharmacyclics. Nasta, S: Consultant Advisory Role: Celgene; Research Funding: Pharmacyclics, Incyte, Roche, Aileron, Rafael/WF, Debiopharm, Takeda/Millenium; Other Remuneration: Merck: DSMC.