Combined KRAS Inhibition and Immune Therapy Generates Durable Complete Responses in an Autochthonous PDAC Model

Abstract Pancreatic ductal adenocarcinoma (PDAC) resists conventional chemo/radiation and immunotherapy (IO). In PDAC, oncogenic KRAS (KRAS*) drives glycolysis in cancer cells to consume available glucose and produce abundant lactate, creating profound immune suppression in the tumor microenvironment. In this study, we combined KRAS* inhibition with agents targeting the major arms of the immunity cycle: CXCR1/2 inhibitor for myeloid cells, antagonistic anti-LAG3 antibody for T cells, and agonistic anti-41BB antibody for dendritic cells. This combination elicited robust antitumor regression in iKPC mice bearing large autochthonous tumors. Whereas untreated mice succumbed within 3 weeks, sustained treatment led to durable complete tumor regression and prolonged survival in 36% of mice at 6 months. Mechanistic analyses revealed enhanced T-cell infiltration and activation, depletion of immunosuppressive myeloid cells, and increased antigen cross-presentation by dendritic cells within the tumor core. These findings highlight the promise of KRAS* inhibitors alongside IO as a potential PDAC treatment avenue, warranting clinical investigation. Significance: Clinically available KRAS* inhibitors and IO agents alleviated the immunosuppressive tumor microenvironment in PDAC. Profound tumor regression and prolonged survival in an autochthonous PDAC model provide a compelling rationale for combining KRAS* inhibition with IO agents targeting multiple arms of the immunity cycle to combat PDAC.