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306 Final Analysis of Keynote-170: Pembrolizumab in Relapsed or Refractory Primary Mediastinal Large B-Cell Lymphoma (PMBCL)Clinically Relevant Abstract

Program: Oral and Poster Abstracts
Type: Oral
Session: 626. Aggressive Lymphomas Prospective Therapeutic Trials: Challenging Populations
Hematology Disease Topics & Pathways:
Clinical Trials, Biological, Adults, Lymphomas, Non-Hodgkin Lymphoma, Clinical Research, Checkpoint Inhibitor, Diseases, Therapies, Lymphoid Malignancies, Study Population
Saturday, December 11, 2021: 5:15 PM

Pier Luigi Zinzani, MD1, Catherine Thieblemont, MD, PhD2, Vladimir Melnichenko3*, Krimo Bouabdallah4*, Jan Waleswski5*, Alejandro Majlis6, Laura Fogliatto7, Alejandro Martin Garcia-Sancho8*, Beth Christian9, Zafer Gulbas10*, Muhit Özcan11, Guilherme Fleury Perini, MD12, Gilles Salles, MD, PhD13, Margaret A. Shipp, MD14, Seth Thompson15*, Samhita Chakraborty15*, Patricia Marinello15* and Philippe Armand16

1IRCCS Azienda Ospedaliero-Universitaria di Bologna Istituto di Ematologia “Seràgnoli” and Dipartimento di Medicina Specialistica, Diagnostica e Sperimentale Università di Bologna, Bologna, Italy
2Hemato-Oncology Department, APHP, Saint-Louis Hospital, Paris, France
3Pirogov National Medical Surgical Center, Moscow, Russian Federation
4Department of Hematology and Cell Therapy, University Hospital, Bordeaux, France
5Maria Sklodowska-Curie National Research Institute of Oncology, European Reference Network, Warszawa, Poland
6Clinica Alemana de Santiago, Vitacura, Chile
7Hospital de Clinicas de Porto Alegre, Porto Alegre, Brazil
8Hematology Department, Hospital Universitario de Salamanca, IBSAL, CIBERONC, Salamanca, Spain
9The James Cancer Hospital and Solove Research Institute, The Ohio State University, Columbus, OH
10Anadolu Medical Center, Gebze, Turkey
11Department of Hematology and Bone Marrow Transplantation Unit, Ankara University Faculty of Medicine, Ankara, Turkey
12Hospital Israelita Albert Einstein, São Paulo, AC, Brazil
13Hématologie, Hospices Civils de Lyon and Université de Lyon, Lyon, France
14Dana-Farber Cancer Institute, Boston, MA
15Merck & Co., Inc., Kenilworth, NJ
16Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA

Introduction: Similar to classical Hodgkin lymphoma, primary mediastinal large B-cell lymphoma (PMBCL) expresses high level of the programmed cell death 1 (PD-1) ligands: PD-L1 and PD-L2. Prior analyses of the phase 2 KEYNOTE-170 (NCT02576990) study demonstrated that monotherapy with the PD-1 inhibitor pembrolizumab had effective antitumor activity and acceptable safety in relapsed/refractory (R/R) PMBCL, leading to FDA approval for adult patients with R/R PMBCL after ≥2 prior therapies. Long-term durability of response with PD-1 blockade in patients with PMBCL, especially those who achieve complete remission (CR), remains a critical clinical question. Here we present updated efficacy and safety of patients with R/R PMBCL in KEYNOTE-170 after ~4 years of follow-up.

Methods: Patients with R/R PMBCL who progressed after or were ineligible for autologous stem cell transplant and received ≥2 prior therapies received pembrolizumab 200 mg every 3 weeks (Q3W) for up to 35 cycles (~2 years). Response assessments were Q12W per 2007 Revised Response Criteria for Malignant Lymphomas. End points included overall response rate (ORR), progression-free survival (PFS), and duration of response (DOR) by investigator assessment; as well as overall survival (OS) and safety. Data cutoff date was October 23, 2020.

Results: At data cutoff, the median duration of follow-up was 48.7 months (range,41.2-56.2). Baseline characteristics of the patients have been previously described (Armand P, et al. J Clin Oncol. 2019; 37(34): 3291-3299). Among all treated patients (N=53), 13 completed 2 years of treatment and 40 patients discontinued, primarily due to progressive disease (n=18). ORR per investigator assessment was 41.5% (95% CI, 30.0-53.7), with 20.8% complete response rate and 20.8% partial response rate. Median DOR was not reached (NR) and 80.6% of patients had a response ≥48 months. Median PFS was 4.3 months (95% CI, 2.8-13.8) and the 48-month PFS rate was 33.0%. Median OS was 22.3 months (95% CI, 7.3-NR) and the 48-month OS rate was 45.3%. At data cutoff, treatment-related adverse events (AEs) of any grade occurred in 30 patients (56.6%); the most commonly reported (incidence >5%) were neutropenia (18.9%), asthenia (9.4%), hypothyroidism (7.5%), and fatigue and pyrexia (5.7% each). Grade 3-4 treatment-related AEs occurred in 22.6% of patients; only neutropenia (n=7) occurred in ≥2 patients. No grade 5 treatment-related AEs occurred.

Conclusions: With 48.7 months of follow-up in heavily pretreated participants with R/R PMBCL, treatment with pembrolizumab monotherapy continued to demonstrate sustained antitumor activity. PFS and OS demonstrated promising trends for long-term survival with no new safety signals identified.

Disclosures: Zinzani: Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Sandoz: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Incyte: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Verastem: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Merck Sharp & Dohme: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; ImmuneDesign: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Bristol Myers Squibb: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; ADC Therapeutics: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Servier: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Kyowa Kirin: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; EUSA Pharma: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; BeiGene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen-Cilag: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; TG Therapeutics Inc: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celltrion: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Portola: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Sanofi: Consultancy, Membership on an entity's Board of Directors or advisory committees; Abbvie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Thieblemont: Bayer: Honoraria; Kyte: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses ; Incyte: Honoraria, Membership on an entity's Board of Directors or advisory committees; Abbvie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses ; Cellectis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses ; Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses ; Hospira: Research Funding; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses , Research Funding; Bristol Myers Squibb/Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses ; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses ; Gilead Sciences: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses . Bouabdallah: Sandoz: Consultancy, Honoraria; Kite/Gilead: Consultancy, Honoraria, Other: Travel/Accommodations/Expenses; Abbvie: Honoraria; Roche: Consultancy, Honoraria, Other: Travel/Accommodations/Expenses; Takeda: Consultancy, Honoraria, Other: Travel/Accommodations/Expenses. Waleswski: Roche: Consultancy, Honoraria, Other: Institution: Research Grant/Funding; Takeda: Consultancy, Honoraria; Servier: Honoraria; Gilead: Consultancy, Honoraria; Amgen: Honoraria; Novartis: Consultancy, Honoraria; GSK/Novartis: Other: Institution: Research Grant/Funding; Abbvie: Consultancy, Honoraria. Fogliatto: AstraZeneca: Speakers Bureau. Martin Garcia-Sancho: Celgene: Honoraria, Other: travel; Celgene/BMS: Consultancy; Janssen: Honoraria, Research Funding; Servier: Consultancy, Honoraria, Other: Travel/Accommodations/Expenses; Gilead: Consultancy, Honoraria; Morphosys: Consultancy; Kyowa Kirin: Consultancy; Clinigen: Consultancy; Eusa Pharma: Consultancy; Novartis: Consultancy; Takeda: Honoraria; Roche: Consultancy, Honoraria, Other: Travel/Accommodations/Expenses; Incyte: Consultancy; Kern Pharma: Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company). Christian: Celgene/BMS: Other: Institution: Research Grant/Funding; Acerta: Other: Institution: Research Grant/Funding; Seattle Genetics: Consultancy, Other: Institution: Research Grant/Funding; Genentech: Consultancy, Other: Institution: Research Grant/Funding; AstraZeneca: Consultancy; VeraStem: Consultancy; Morphosys: Consultancy, Other: Institution: Research Grant/Funding; Triphase: Other: Institution: Research Grant/Funding; Millenium: Other: Institution: Research Grant/Funding; Immunomedics: Other: Institution: Research Grant/Funding; Merck: Other: Institution: Research Grant/Funding. Özcan: Amgen: Honoraria, Other: Travel/Accommodations/Expenses; Janssen: Other: Travel/Accommodations/Expenses, Research Funding; Celgene: Research Funding; Archigen: Research Funding; Roche: Other: Travel/Accommodations/Expenses, Research Funding; Bayer: Research Funding; AstraZeneca: Research Funding; Takeda: Honoraria, Other: Travel/Accommodations/Expenses, Research Funding; Pfizer: Research Funding; BMS: Other: Travel/Accommodations/Expenses; Abbvie: Other: Travel/Accommodations/Expenses, Research Funding; Jazz: Other: Travel/Accommodations/Expenses; Abdi Ibrahim: Other: Travel/Accommodations/Expenses; Sanofi: Other: Travel/Accommodations/Expenses; MSD: Research Funding. Perini: Takeda: Speakers Bureau; Roche: Consultancy, Speakers Bureau; AstraZeneca: Consultancy, Speakers Bureau; Abbvie: Consultancy, Other: Travel/Accommodations/Expenses, Speakers Bureau; MSD: Consultancy, Speakers Bureau; Janssen: Consultancy, Other: Travel/Accommodations/Expenses, Speakers Bureau. Salles: Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Miltenyi: Consultancy; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Debiopharm: Consultancy, Membership on an entity's Board of Directors or advisory committees; Kite/Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees; Genmab: Consultancy, Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb/Celgene: Consultancy, Honoraria; Incyte: Consultancy, Membership on an entity's Board of Directors or advisory committees; Bayer: Honoraria; AbbVie: Consultancy, Honoraria; BeiGene: Consultancy, Membership on an entity's Board of Directors or advisory committees; Loxo: Consultancy, Membership on an entity's Board of Directors or advisory committees; Roche/Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees; Morphosys: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Ipsen: Consultancy; Epizyme: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Rapt: Consultancy, Membership on an entity's Board of Directors or advisory committees; Regeneron: Consultancy, Honoraria; Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees; Velosbio: Consultancy, Membership on an entity's Board of Directors or advisory committees; Allogene: Consultancy. Shipp: Bayer: Other: Institution: Research Grant/Funding; AstraZeneca: Consultancy, Research Funding; Abbvie: Other: Institution: Research Grant/Funding; Immunitas Therapeutics: Consultancy; Merck: Research Funding; Bristol Myers Squibb: Research Funding. Thompson: Merck & Co., Inc.: Current Employment, Other: Current Stockholder. Chakraborty: Merck & Co., Inc.: Current Employment, Other: Current Stockholder. Marinello: Merck & Co., Inc.: Current Employment, Other: Current Stockholder. Armand: Merck: Consultancy, Honoraria, Research Funding; BMS: Consultancy, Honoraria, Research Funding; Pfizer: Consultancy; Affimed: Consultancy, Research Funding; Adaptive: Consultancy, Research Funding; Infinity: Consultancy; ADC Therapeutics: Consultancy; Celgene: Consultancy; Morphosys: Consultancy; Daiichi Sankyo: Consultancy; Miltenyi: Consultancy; Tessa: Consultancy; GenMab: Consultancy; C4: Consultancy; Enterome: Consultancy; Regeneron: Consultancy; Epizyme: Consultancy; AstraZeneca: Consultancy; Genentech: Consultancy, Research Funding; Roche: Research Funding; Tensha: Research Funding; Otsuka: Research Funding; Sigma Tau: Research Funding; IGM: Research Funding; Kite: Research Funding.

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