Reprogramming the Intrahepatic Cholangiocarcinoma Immune Microenvironment by Chemotherapy and CTLA-4 Blockade Enhances Anti-PD1 Therapy (scRNA-seq)

Intrahepatic cholangiocarcinoma (ICC) has limited therapeutic options and a dismal prognosis. Adding blockade of the PD1 pathway to gemcitabine/cisplatin chemotherapy has recently shown efficacy in biliary tract cancers but with low response rates. Here, we studied the effects of anti-CTLA-4 when combined with anti-PD1 and gemcitabine/cisplatin in orthotopic murine models of ICC. This combination therapy led to substantial survival benefits and reduction of morbidity in two aggressive ICC models that were resistant to immunotherapy alone. Gemcitabine/cisplatin treatment increased tumor-infiltrating lymphocytes and normalized the ICC vessels, and when combined with dual CTLA-4/PD1 blockade, increased the number of activated CD8+Cxcr3+IFN?+ T cells. CD8+T cells were necessary for the therapeutic benefit because the efficacy was compromised when CD8+ T cells were depleted. Expression of Cxcr3 on CD8+ T cells is necessary and sufficient since CD8+ T cells from Cxcr3+/+ but not Cxcr3–/– mice rescued efficacy in T cell?deficient mice. Finally, rational scheduling of anti-CTLA-4 “priming” with chemotherapy followed by anti-PD1 therapy achieved equivalent efficacy with reduced overall drug exposure. These data suggest that this combination approach should be clinically tested to overcome resistance to current therapies in ICC patients. Overall design: We isolated single cells from tumor tissues of 425-ICC in mice that received either gemcitabine/cisplatin (GC, n=2 mice) treatment alone or a combination of GC and dual ICB (anti-PD1 plus anti-CTLA-4, n=3 mice) on day 10 after treatment for single-cell RNA sequencing (scRNA-seq) analysis. A magnetically activated cell sorting (MACS) column was used to obtain CD45+ and CD45– cells from each tumor sample, and then the cells were mixed at a ratio of 1:1 and captured using the 10x Chromium controller.