Abstract 3732: Peripheral pharmacodynamic activity of epcoritamab as monotherapy and in combination with rituximab + lenalidomide in patients with follicular lymphoma

Abstract Introduction: Epcoritamab (DuoBody®-CD3xCD20) is a subcutaneous IgG1 bispecific antibody that simultaneously binds to CD3 on T cells and CD20 on malignant B cells, inducing activation and cytotoxic activity of T cells to mediate killing of target lymphoma cells. Epcoritamab is approved in the US for the treatment of adults with relapsed/refractory (R/R) diffuse and high-grade large B-cell lymphoma after ≥2 lines of systemic therapy (also approved in Europe, the UK, Japan, and Canada). Here we present the pharmacodynamic effects of epcoritamab as monotherapy (EPCORE NHL-1: NCT03625037) or in combination with rituximab + lenalidomide (R2) (EPCORE NHL-2: NCT04663347) in peripheral blood of patients with follicular lymphoma (FL), a heterogeneous disease for which many patients have an unmet medical need for efficacious, well-tolerated, off-the-shelf therapies. Methods: In EPCORE NHL-1 expansion phase, adults with R/R FL received epcoritamab monotherapy; in EPCORE NHL-2, adults with R/R (arm 2) or newly diagnosed (ND) (arm 6) FL received epcoritamab combined with R2. B-cell markers and T-cell proliferation and activation markers in whole blood were assessed using validated flow cytometry assays. Cytokines in plasma were measured using a validated multiplex immunoassay. Results: Epcoritamab as monotherapy and in combination with R2 induced rapid depletion of circulating peripheral B cells (CD19+) in patients with detectable peripheral B cells at baseline. Additionally, within the first 2 cycles, epcoritamab monotherapy induced a transient elevation of peripheral CD8+ and CD4+ T cells expressing proliferation (Ki67+%) and activation (HLA-DR+% and PD-1+%) markers. R/R and ND patient groups treated with epcoritamab + R2 showed a trend for greater induction of proliferating and activated peripheral T cells. Likewise, elevation in T-cell absolute counts was observed from cycle 2 onward, with a trend of higher levels with epcoritamab + R2 vs epcoritamab monotherapy. In addition, a moderate but transient elevation of circulating cytokines including IFNγ, IL-6, and IL-10 during cycle 1 was observed with epcoritamab monotherapy and epcoritamab + R2. Importantly, IL-6 and IL-10 returned to approximate baseline levels prior to the subsequent dose. Compared with epcoritamab monotherapy, patients treated with epcoritamab + R2 showed a trend for lower median levels of IL-6 peaks 24 hours after the first full dose. Conclusion: The pharmacodynamic activity of epcoritamab combined with R2 in R/R and ND FL was consistent with epcoritamab’s mechanism of action as monotherapy. Epcoritamab + R2 showed a favorable pharmacodynamic profile with a trend toward increased T-cell activation and T-cell elevation, and lower IL-6 levels. These data support the ongoing phase 3 trial of epcoritamab + R2 compared with R2 alone in patients with R/R FL (EPCORE FL-1: NCT05409066). Citation Format: Han Si, Jimin Zhang, Monica Wielgos-Bonvallet, Lorenzo Falchi, Kim Linton, Wojciech Jurczak, David Belada, Işıl Altıntaş, Mariana Sacchi, Elena Favaro, Ali Rana, Daniela Hoehn, David Soong, Christopher W. Chiu, Maria Jure-Kunkel. Peripheral pharmacodynamic activity of epcoritamab as monotherapy and in combination with rituximab + lenalidomide in patients with follicular lymphoma abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (6Suppl): Abstract nr 3732.