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6 Mosunetuzumab Induces Complete Remissions in Poor Prognosis Non-Hodgkin Lymphoma Patients, Including Those Who Are Resistant to or Relapsing After Chimeric Antigen Receptor T-Cell (CAR-T) Therapies, and Is Active in Treatment through Multiple Lines

Program: General Sessions
Session: Plenary Scientific Session
Hematology Disease Topics & Pathways:
antibodies, Follicular Lymphoma, CRS, Diseases, Biological, Therapies, neurotoxicity, Adverse Events, CAR-Ts, Non-Hodgkin Lymphoma, DLBCL, immunotherapy, Lymphoid Malignancies
Sunday, December 8, 2019, 2:00 PM-4:00 PM
Hall D, Level 2 (Orange County Convention Center)

Stephen J Schuster, MD1, Nancy L Bartlett, MD2*, Sarit Assouline, MD3, Sung-Soo Yoon, MD, PhD4, Francesc Bosch, MD, PhD5, Laurie H Sehn, MD6, Chan Y. Cheah7, Mazyar Shadman, MD, MPH8*, Gareth P Gregory, MBBS (Hons), PhD, FRACP, FRCPA9, Matthew Ku, MBBS, FRACP, FRCPA, PhD10*, Michael C Wei, MD, PhD11, Shen Yin, PhD11, Antonia Kwan, MD, PhD, MRCPCH11*, Kasra Yousefi, MSc12*, Genevive Hernandez, PhD11*, Chi-Chung Li, PhD11*, Carol O’Hear, MD, PhD11* and Lihua E Budde, MD, PhD13

1Lymphoma Program, Abramson Cancer Center, University of Pennsylvania, Philadelphia, PA
2Siteman Cancer Center, Washington University School of Medicine, St. Louis, MO
3Jewish General Hospital, Montreal, QC, Canada
4Seoul National University Hospital, Seoul, Korea, Republic of (South)
5University Hospital Vall d’Hebron, Barcelona, Spain
6BC Cancer Centre for Lymphoid Cancer and University of British Columbia, Vancouver, BC, Canada
7Linear Clinical Research and Sir Charles Gairdner Hospital, Perth, WA, Australia
8Fred Hutchinson Cancer Research Center, Seattle, WA
9Monash Health and School of Clinical Sciences at Monash Health, Monash University, Clayton, VIC, Australia
10St Vincent's Hospital, University of Melbourne, Melbourne, VIC, Australia
11Genentech, Inc., South San Francisco, CA
12Hoffmann-La Roche Limited, Mississauga, ON, Canada
13City of Hope, Duarte, CA

Introduction: Improved treatments are needed for relapsed or refractory (R/R) non-Hodgkin lymphoma (NHL) pts. Options are particularly limited for pts with B-cell NHLs who are R/R to CAR-T therapies or for whom a delay in effective therapy precludes this approach. Mosunetuzumab (M; RG7828) is a full-length, fully humanized immunoglobulin G1 (IgG1) bispecific antibody targeting both CD3 (on the surface of T cells) and CD20 (on the surface of B cells). In an ongoing Phase I/Ib study (GO29781; NCT02500407), promising efficacy and favorable tolerability were observed in R/R NHL pts (Budde et al. ASH 2018; Bartlett et al. ASCO 2019). We report complete remissions (CRs) with M in NHL pts who are R/R to CAR-T therapy, as well as activity with M re-treatment.

Methods: GO29781 is an open-label, multicenter, Phase I/Ib, dose escalation and expansion study of M in R/R B-cell NHL. Data is presented from Group B, in which M is administered with step-up dosing on Days 1, 8, and 15 of Cycle 1, and then as a fixed dose on Day 1 of each subsequent 21-day cycle (maximum 17 cycles). Outcome measures include best objective response rate (ORR) by revised International Working Group criteria, maximum tolerated dose (MTD), and tolerability.

Results: As of June 4, 2019, 218 pts in Group B had received any amount of M. Indolent NHL (iNHL) pts (n=72) were mainly follicular lymphoma (FL, n=69). Aggressive NHL (aNHL) pts (n=141) were mainly diffuse large B-cell lymphoma (DLBCL, n=87) or transformed FL (trFL, n=29). Median prior systemic therapies was 3 (range: 1–14). Twenty-three pts had prior CAR-T therapy (12 DLBCL, 6 trFL, 5 FL), and 16 were efficacy evaluable (7 DLBCL, 5 trFL, 4 FL). ORR and CR rates were 43.8% (7/16) and 25.0% (4/16, 2 DLBCL and 2 FL), respectively. Expansion of previously administered CAR-Ts after M administration was detected by quantitative PCR, in line with the mechanism of action of M.

Dose escalation is ongoing, supported by a positive exposure-response relationship for efficacy and broad therapeutic window with step-up dosing (Li et al. ASH 2019). Among efficacy-evaluable pts across all dose levels, ORR and CR rates were 64.1% (41/64) and 42.2% (27/64) in iNHL pts and 34.7% (41/119) and 18.6% (22/119) in aNHL pts, respectively.

CRs appeared durable, with 25/27 (92.6%) iNHL pts (median time from first CR: 5.8 months; range: 0.2–28.9) and 15/22 (68.2%) aNHL pts (median time from first CR: 8.8 months; range: 0.0–25.4) who achieved CR remaining in remission. Re-treatment with M was allowed in CR pts who relapsed. Four pts, including 1 in Group A who was initially treated with a fixed, non-step-up dosing schedule, received M re-treatment. One CR and 2 partial responses were observed. All three responses are ongoing, with the CR pt in second remission for 314 days.

The MTD of M has not been reached at doses up to 1/2/60mg (Cycle 1 Day 1, 8, and 15). Adverse events (AEs) leading to treatment withdrawal were uncommon (12/218, 5.5%). Cytokine release syndrome (CRS), graded by Lee criteria (Lee et al. Blood 2014;124:188–95), was observed in 28.4% of pts, and was mostly Grade (Gr) 1 (21.1%) or Gr 2 (6.0%); Gr 3 CRS occurred in 1.4% of pts. Most CRS events occurred in Cycle 1; 5 pts (2.7%) had CRS during or after Cycle 2. Three of 218 pts (1.4%) received tocilizumab for CRS management; all 3 events resolved without sequelae (for 1 pt, CRS resolved after the cutoff date). Neurological AEs (NAEs) were reported in 44% of pts (Gr 1, 28.0%; Gr 2, 12.8%; Gr 3, 3.2%). Common NAEs were headache (14.7%), insomnia (10.1%), and dizziness (9.2%). Potential immune effector cell-associated neurotoxicity syndrome (ICANS)-like NAEs of Gr 1 or Gr 2 confusional state occurred in 3 pts (1.4%) during cycles 1 and 2. The frequency of CRS and NAEs did not correlate with M exposure, likely due to step-up dosing, which effectively mitigates acute toxicities and allows administration of higher doses (Bartlett et al. ASCO 2019; Li et al. ASH 2019). Among the 4 pts who were re-treated with M, no CRS was observed and NAEs were reported in 1 pt (Gr 1 headache and insomnia). Among the 23 pts who were R/R to CAR-T therapy, CRS occurred in 5 pts (21.7%; Gr 1, 13.0%; Gr 2, 4.3%; Gr 3, 4.3%) and NAEs in 8 pts (34.8%; Gr 1, 17.4%; Gr 2, 13.0%; Gr 3, 4.3%), with no ICANS-like events.

Conclusions: M has favorable tolerability and durable efficacy in pts with heavily pre-treated R/R B-cell NHL, including CRs in pts with disease progression after CAR-T therapies. Preliminary data support the possibility for re-treatment with M.

Disclosures: Schuster: Celgene: Consultancy, Honoraria, Research Funding; Genentech: Consultancy, Honoraria, Research Funding; Merck: Consultancy, Honoraria, Research Funding; Pharmacyclics: Consultancy, Honoraria, Research Funding; Acerta: Consultancy, Honoraria, Research Funding; AbbVie: Consultancy, Honoraria, Research Funding; Gilead: Consultancy, Honoraria, Research Funding; Nordic Nanovector: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; AstraZeneca: Consultancy, Honoraria; Loxo Oncology: Consultancy, Honoraria; Novartis: Honoraria, Patents & Royalties: Combination CAR-T and PD-1 Inhibitors, Research Funding. Bartlett: Bristol-Myers Squibb: Research Funding; Celgene: Research Funding; Kite Pharma: Research Funding; Merck: Research Funding; Millennium: Research Funding; Pfizer: Research Funding; Pharmacyclics: Research Funding; Gilead: Research Funding; Immune Design: Research Funding; Incyte: Research Funding; Janssen: Research Funding; ADC Therapeutics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Affimed: Research Funding; Autolus: Research Funding; Forty Seven: Research Funding; Genentech, Inc.: Research Funding. Assouline: Janssen: Consultancy, Honoraria, Speakers Bureau; Abbvie: Consultancy, Honoraria; F. Hoffmann-La Roche Ltd: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria, Speakers Bureau. Yoon: Kyowa Hako Kirin: Research Funding; Genentech, Inc.: Research Funding; Novartis: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; MSD: Consultancy; Janssen: Consultancy; Yuhan Pharma: Research Funding. Bosch: Kyte: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Acerta: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Celgene: Honoraria, Research Funding; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Takeda: Honoraria, Research Funding; AstraZeneca: Honoraria, Research Funding; F. Hoffmann-La Roche Ltd/Genentech, Inc.: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau. Sehn: Janssen-Ortho: Consultancy, Honoraria; Janssen-Ortho: Honoraria; Merck: Consultancy, Honoraria; Merck: Consultancy, Honoraria; TG Therapeutics: Consultancy, Honoraria; TG Therapeutics: Consultancy, Honoraria; Lundbeck: Consultancy, Honoraria; Lundbeck: Consultancy, Honoraria; Kite Pharma: Consultancy, Honoraria; Kite Pharma: Consultancy, Honoraria; Acerta: Consultancy, Honoraria; Astra Zeneca: Consultancy, Honoraria; Acerta: Consultancy, Honoraria; Seattle Genetics: Consultancy, Honoraria; Astra Zeneca: Consultancy, Honoraria; TEVA Pharmaceuticals Industries: Consultancy, Honoraria; Seattle Genetics: Consultancy, Honoraria; Morphosys: Consultancy, Honoraria; TEVA Pharmaceuticals Industries: Consultancy, Honoraria; F. Hoffmann-La Roche/Genentech: Consultancy, Honoraria, Research Funding; Morphosys: Consultancy, Honoraria; F. Hoffmann-La Roche/Genentech: Consultancy, Honoraria, Research Funding; Abbvie: Consultancy, Honoraria; Abbvie: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; Apobiologix: Consultancy, Honoraria; Celgene: Consultancy, Honoraria; Gilead: Consultancy, Honoraria; Karyopharm: Consultancy, Honoraria; Takeda: Consultancy, Honoraria; Verastem: Consultancy, Honoraria. Cheah: Janssen: Honoraria; Acerta: Honoraria; F. Hoffmann-La Roche Ltd: Honoraria, Research Funding; AbbVie: Research Funding; Celgene: Research Funding; Gilead: Honoraria; Loxo: Honoraria. Shadman: Mustang Biopharma: Research Funding; Gilead: Research Funding; AbbVIe: Consultancy, Research Funding; Genentech, Inc.: Consultancy, Research Funding; AstraZeneca: Consultancy; Sound Biologics: Consultancy; Pharmacyclics: Consultancy, Research Funding; ADC Therapeutics: Consultancy; Atara: Consultancy; Bigene: Research Funding; Celgene: Research Funding; TG Therapeutics: Research Funding; Verastem: Consultancy; Acerta: Research Funding; Emergent: Research Funding; Sunesis: Research Funding; Merck: Research Funding. Gregory: AbbVie: Research Funding. Wei: Genentech, Inc./F. Hoffmann-La Roche Ltd: Employment, Equity Ownership. Yin: Genentech, Inc: Employment, Equity Ownership. Kwan: Genentech, Inc: Employment, Equity Ownership. Yousefi: F. Hoffmann-La Roche Ltd: Employment. Hernandez: Genentech, Inc.: Employment, Equity Ownership. Li: F. Hoffmann-La Roche Ltd: Employment, Equity Ownership. O’Hear: F. Hoffmann-La Roche Ltd: Equity Ownership; Genentech, Inc.: Employment. Budde: F. Hoffmann-La Roche Ltd: Consultancy.

OffLabel Disclosure: Mosunetuzumab (RG7828) is a full-length, fully humanized immunoglobulin G1 (IgG1) bispecific antibody targeting both CD3 (on the surface of T cells) and CD20 (on the surface of B cells). Mosunetuzumab redirects T cells to engage and eliminate malignant B cells. Mosunetuzumab is an investigational agent.

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