Abstract C038: Interim pharmacodynamic analyses of mitazalimab in combination with FOLFIRINOX in first-line metastatic pancreatic ductal adenocarcinoma (mPDAC) identify CD4 effector T cells as a correlate of treatment outcomes

Abstract

Abstract CD40 agonists are being investigated in combination with standard of care chemotherapy as an approach to trigger anti-tumor immunity and improve outcomes for patients with cancer. Preclinical models suggest the importance of appropriate sequencing of chemotherapy and a CD40 agonist. Herein, we report interim pharmacodynamic analyses and their association with outcomes from a Phase 2 study evaluating mitazalimab, a CD40 agonist, in combination with modified (m) FOLFIRINOX chemotherapy as first line therapy in patients with metastatic pancreatic ductal adenocarcinoma (mPDAC). Patients with newly diagnosed mPDAC were treated with mitazalimab on day 1 prior to beginning an every 2-week regimen on day 8 of mFOLFIRINOX followed by mitazalimab 48 hours later. Tumor response was determined by RECIST v1.1 imaging. Peripheral blood was analyzed for selected cytokines and chemokines and by flow cytometry to assess changes in leukocyte subsets including B cells, monocytes, T cells, and NK cells. The neutrophil-to-lymphocyte ratio was determined from complete blood counts. The analysis included 23 patients with associated response data and indicated a mitazalimab-specific contribution to tumor response. Mitazalimab triggered an expected immune response characterized by transient cytokine (IL-8, IP-10, MCP-1, and MIP1b) release and B cell depletion. Chemotherapy provoked a reduction in classical monocytes and proliferating CD4+ T cells. Both mitazalimab and chemotherapy caused a transient reduction in circulating dendritic cells and NK cells. Tumor response was associated with an expansion in the frequency of effector CD4 T cells (p < 0.0001) at day 8 after receiving mitazalimab but did not correlate with neutrophil-to-lymphocyte ratio (p = 0.851). In conclusion, mitazalimab and FOLFIRINOX modulate immune responses in patients with mPDAC in different ways. Interim results of pharmacological analyses identify CD4 effector T cells as a correlate of treatment outcomes suggesting the contribution of mitazalimab to tumor responses. Citation Format: Max M. Wattenberg, Karin Enell Smith, Yago Pico de Coana, David Gomez Jimenez, Malin Carlsson, Sumeet Vijay Ambarkhane, Peter Ellmark, Gregory L. Beatty. Interim pharmacodynamic analyses of mitazalimab in combination with FOLFIRINOX in first-line metastatic pancreatic ductal adenocarcinoma (mPDAC) identify CD4 effector T cells as a correlate of treatment outcomes [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr C038.