Optimized multidrug therapy remodels the tumor microenvironment and enhances antitumor immunity in microsatellite-stable colorectal cancer

Four low-dose tyrosine kinase inhibitor (TKI)–based ODCs were evaluated in murine AKP CRC organoids, co-culture systems with tumor-associated endothelial cells and immune cells, and in vivo syngeneic models. Among these, ODCDLD1 (regorafenib, vemurafenib, erlotinib HCl, selumetinib) showed the most potent inhibition of tumor organoid viability (~90%), promoted leukocyte infiltration in co-cultures, and significantly upregulated endothelial adhesion molecules (ICAM-1, VCAM-1, E-selectin). In vivo, ODCDLD1 reduced tumor growth comparably to oxaliplatin but with a favorable toxicity profile. Immunofluorescence analysis revealed that both ODCDLD1 and oxaliplatin significantly reduced the population of proliferating cancer cells. Furthermore, ODCDLD1-based treatment recapitulated transcriptomic findings by showing a significant reduction in proliferating myofibroblasts, a key stromal component. Bulk RNA sequencing revealed that ODCDLD1, especially when combined with anti-PD-1, induced an immunologically “hot” tumor microenvironment characterized by enhanced immune cell recruitment, reduced fibroblast and stem-like cell signatures, and upregulation of endothelial markers. Overall design: CRC AKP sc tumors derived from mice treated with different drug combinaitons