Background: Esophageal adenocarcinoma (EAC) is a leading cause of cancer deaths. Pexidartinib, is a multi-gene tyrosine kinase inhibitor, targeting FLT3, KIT and CSF1R. In particular, pexidartinib by targeting CSF-1R down modulates macrophage mediated pro-survival tumor signaling. Recently, CSF-1R inhibitors have successfully shown to enhance antitumor activity of PD-1/PD-L1 inhibitors by suppressing tumor immune evasion, in multiple solid tumors. Methods: Seventy-two rats underwent an end-to-side esophagojejunostomy to induce gastroesophageal reflux, resulting in EAC carcinogenesis. At 32 weeks postoperatively, tumor bearing animals were randomized to a dose of 30mg/kg of pexidartinib or vehicle control, 5 days on and 2 days off (14 day cycle), for a total of 3 cycles. A PD-1 inhibitor, AUNP-12, at a dose of 3mg/kg or placebo, was administered on day 12 of each cycle. At 38 weeks postoperatively animals were euthanized. Safety and efficacy was evaluated by objective health assessments, pre and posttreatment MRI, RT-PCR, immunofluorescent labeling and a serum cytokine assay. Results: The pexidartinib +/- PD-1 inhibitor (Px+P and Px-P) groups demonstrated no significant difference in daily weight change (p = 0.98) or in mortality (p = 0.59) when compared to vehicle control (V+P and V-P) groups. On post-mortem serum analysis AST (p = 0.01) and ALT (p = 0.001) were elevated, while albumin (p = 0.57) and BUN/creatinine ratio (p = 0.09) were reported within normal ranges, when comparing treatment to placebo groups. Pre to posttreatment, mean MRI tumor volume decreased by 37% and 54% in the Px-P and Px+P animals and increased by 147% and 88% in the V+P and V-P animals, respectively (p = < 0.0001). Overall response rate was 69% and 87% in Px-P and Px+P animals compared to 21% and 13% in V-P and V+P animals, respectively (p = < 0.0001). Downstream gene expression demonstrated upregulation of TNF-α (p = 0.003), IFN-γ (p = 0.002) and IL-6 (p = 0.0001) and downregulation of IL-13 (p = 0.051), IL-10 (p = 0.051), TGF-β (p = 0.024) and Arg-1 (p = 0.0003), in treatment vs. placebo animals. Increased apoptosis (Cas-3 p = 0.0005) and reduced proliferation (Ki-67 p = < 0.0001) were reported in the treatment animals. Higher CD3⁺CD8⁺ T cell densities and CD86/CD206 macrophage ratio was reported in treatment groups compared to placebo (p = < 0.0001). Serum cytokine levels significantly displayed upregulation of TNF-α and IFN-γ and downregulation of IL-4 and IL-10 in the treatment animals compared to the placebo. Conclusions: Overall, this study established a promising combinatorial strategy using a CSF-1R inhibitor to overcome resistance to PD-1/PD-L1 axis blockade in an esophageal cancer model, providing the rationale for future clinical strategies.