Abstract 6746: Biomarker-driven restoration of tumor provisional matrix signaling network reverses resistance to checkpoint inhibition immunotherapy

Abstract Specialized immune niches located in the stroma-tumor junction promote interactions between tumor-resident antigen-presenting cells and effector lymphocytes that are required for immunotherapy efficacy. We have hypothesized that this stromal-based immune crosstalk may be regulated by provisional extracellular matrix signals, analogous to the early-stages of wound healing where provisional matrix hosts robust immune activity. A cardinal provisional matrix remodeling event, the regulated proteolysis of the large proteoglycan versican (VCAN) generates an immunomodulatory fragment (matrikine), versikine, that engages adaptive immunity. We have previously shown that VCAN proteolysis correlates with T-cell infiltration across multiple solid and liquid cancers with the most immune-evasive cancers showing low to negligible rates of VCAN proteolysis (e.g., 0% in pancreatic adenocarcinoma). A recent clinical trial generated informative prospective data linking VCAN proteolysis with immunotherapy outcomes: patients whose metastatic colorectal tumors categorized as VCAN proteolysis-weak (VPW, 60% of cases) demonstrated inferior responses to checkpoint inhibition (CPI, pembrolizumab) and worse outcomes compared to VCAN proteolysis-predominant (VPP, 40%) cases. Leveraging these prospective trial data, we hypothesized that versikine therapy may rationally reverse the immunosuppression associated with the prevalent VPW phenotype. To tailor versikine therapy to specific human biomarker-stratified tumor phenotypes, we studied experimental models replicating partially T-permissive VPW-VCANlo human cancers and poor-prognosis, immune-exclusionary VPW-VCANhi cancers. Across VPW-like tumors, versikine promoted the stromal accumulation of CD40lghiIcoshiFoxp3neg Tfh-like CD4+ T cells that engaged dendritic cells (DC) and CD8+ T cells in “immune triads” even at baseline (prior to CPI), concurrently with the intratumoral expansion of activated CD8+ T cells expressing cytolytic molecules (granzymes, perforin). In VPW-VCANlo tumors, versikine delivered as LNP-mRNA or recombinant protein demonstrated monotherapy activity, dependent on Batf3-lineage DC and CD8+ T cells. When combined with single-agent CPI, versikine cured most VPW-VCANlo tumors with memory to tumor re-challenge. In VPW-VCANhi tumors, versikine synergized with combination immunotherapy modulating “mature DCs enriched in immunoregulatory molecules” (mregDC). Our data provide mechanistic rationale for the biomarker-stratified, therapeutic restoration of a provisional matrix-regulated immune signaling network to reverse resistance to CPI. Moreover, the data highlight the need to reevaluate prior approaches to globally disrupt tumor stroma in favor of biomarker-driven, pathway-focused harnessing of stromal signals that modulate anti-tumor immunity. Citation Format: Daniel J. Lagal, Duncan Hong, Athanasios Papadas, Emma Geatches, George Yacu, Surabhi Naik, Alicia Gibbons, Alexander Cicala, Kersi Pestonjamasp, Peter Toth, Kristina Matkowskyj, Dustin A. Deming, Fotis Asimakopoulos. Biomarker-driven restoration of tumor provisional matrix signaling network reverses resistance to checkpoint inhibition immunotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 6746.