Subcutaneous Epcoritamab Induces Complete Responses with an Encouraging Safety Profile across Relapsed/Refractory B-Cell Non-Hodgkin Lymphoma Subtypes, Including Patients with Prior CAR-T Therapy: Updated Dose Escalation Data

Introduction: Despite advances in the treatment of B-cell non-Hodgkin lymphoma (B-NHL), more efficacious, less toxic, off-the-shelf therapies are needed for patients (pts) with relapsed or refractory (R/R) disease. Epcoritamab is a novel, subcutaneously (SC) administered bispecific antibody (bsAb) that simultaneously binds to CD3 on T cells and CD20 on B cells, inducing activation and cytotoxic activity of T cells for killing of target lymphoma cells. In an open-label, phase 1/2 trial (NCT03625037), initial data demonstrated an encouraging safety profile and potent single-agent clinical activity, even at low doses, in heavily pretreated pts with R/R B-NHL (Hutchings M. EHA 2020, Poster EP1218). Herein, we present updated dose-escalation data, including initial results for the 48-mg recommended phase 2 dose (RP2D) and for pts with mantle cell lymphoma (MCL). Methods: Adults with R/R CD20+ B-NHL after prior therapy, including an anti-CD20 monoclonal antibody (mAb), receive a SC 1-mL injection of flat-dose epcoritamab in 28-day cycles (q1w: cycles 1-2; q2w: cycles 3-6; q4w thereafter) until disease progression or unacceptable toxicity. Risk mitigation for cytokine release syndrome (CRS) includes starting with priming and intermediate doses and use of corticosteroids. Objectives include dose finding, safety, and antitumor activity. Results: As of July 6, 2020, 67 pts were enrolled, which included 45 pts (67%) with diffuse large B-cell lymphoma (DLBCL), 12 (18%) with follicular lymphoma (FL) and 4 (6%) with MCL. Pts were heavily pretreated, with a median (range) of 3.0 (1-6) prior lines of therapy for pts with DLBCL and 4.5 (1-18) for pts with FL; in total 6 pts had received prior CAR-T therapy. Over one-half of pts (37/67; 55%) were refractory to their most recent systemic therapy; 35/67 (52%) were refractory to their most recent anti-CD20 mAb therapy. At a median overall follow-up of 8.3 months, treatment is ongoing in 25 pts (37%); median follow-up is 8.3 months for pts with DLBCL and 8.8 months for pts with FL. Epcoritamab was well tolerated and there were no discontinuations due to treatment-related adverse events (AEs). The most common treatment-emergent AEs (TEAEs) were pyrexia (70%), local injection-site reactions (48%), and fatigue (45%). With increased doses, TEAEs of special interest were consistent with previous reports: CRS events were all grade 1/2 (58%) with no grade 3/4 CRS events, and limited neurotoxicity was observed (6%; grade 1: 3%; grade 3