biostudies-literatureKrykbaeva INational Cancer InstituteNCI NIH HHS1332-1350https://www.ebi.ac.uk/biostudies/studies/S-EPMC12645833biostudies-literatureUnknown11(10)Checkpoint inhibitors have revolutionized cancer treatment, but resistance remains a significant clinical challenge. Myeloid cells within the tumor microenvironment can modulate checkpoint resistance by either supporting or suppressing adaptive immune responses. Using an anti-PD-1-resistant mouse melanoma model, we show that targeting the myeloid compartment via CD40 activation and CSF1R blockade in combination with anti-PD-1 results in complete tumor regression in a majority of mice. This triple therapy combination was primarily CD40 agonist-driven in the first 24 hours after therapy and showed a similar systemic cytokine profile in human patients as was seen in mice. Functional single-cell cytokine secretion profiling of dendritic cells (DC) using a novel microwell assay identified a CCLCancer immunology researchCombinatorial Immunotherapy with Agonistic CD40 Activates Dendritic Cells to Express IL12 and Overcomes PD-1 Resistance.PMC12645833F30 CA228444U01CA238728U01 CA238728F30CA228444Weiss SAPark KOlino KBridges KKluger HMMcGeary MKMiller-Jensen KAlexander AFKaech SMPizzurro GAEyles JTurner NKrykbaeva IDamsky WBosenberg MLuheshi NMuthusamy VfalseCombinatorial Immunotherapy with Agonistic CD40 Activates Dendritic Cells to Express IL12 and Overcomes PD-1 Resistance.Checkpoint inhibitors have revolutionized cancer treatment, but resistance remains a significant clinical challenge. Myeloid cells within the tumor microenvironment can modulate checkpoint resistance by either supporting or suppressing adaptive immune responses. Using an anti-PD-1-resistant mouse melanoma model, we show that targeting the myeloid compartment via CD40 activation and CSF1R blockade in combination with anti-PD-1 results in complete tumor regression in a majority of mice. This triple therapy combination was primarily CD40 agonist-driven in the first 24 hours after therapy and showed a similar systemic cytokine profile in human patients as was seen in mice. Functional single-cell cytokine secretion profiling of dendritic cells (DC) using a novel microwell assay identified a CCL2023-01-01T00:00:00Z2023 Oct2026-06-05T19:11:42.132Z2026-05-20T03:14:33.872ZS-EPMC126458333747817110.1158/2326-6066.CIR-22-069910.1158/2326-6066.cir-22-0699