Immunotherapy has become the standard treatment for many types of cancers, but an increasing number of patients who initially respond to these treatments develop acquired immunotherapy resistance (AIR). Here, we recapitulated the entire process of immunotherapy from response to AIR in mice with non-small cell lung cancer (NSCLC). With implanted tumor organoids derived from these models and serial transplants, we demonstrated that tumor cell-intrinsic mechanisms contributed significantly to AIR. Single-cell RNA sequencing and electron microscope assays revealed that resistant tumor cell-expressing collagens, including Col3a1 and Col6a1, formed multiple physical barriers surrounding tumor cells. Disruption of these barriers by collagenase or knockout of both Col3a1 and Col6a1 in tumor cells could sensitize the tumors of AIR. Mechanistically, the TGFβ pathway was upregulated upon immunotherapy, and treatment with TGFβ significantly increased the expression levels of both Col3a1 and Col6a1 in tumor cells. COL3A1 formed a castle-like barrier for a cluster of tumor cells and prevented T cell infiltration, while COL6A1 formed an armor-like barrier surrounding individual tumor cells to protect them against direct T cell attack. Our data reveal a tumor cell-intrinsic mechanism of AIR, mediated by collagen-containing physical barriers, which immediately suggests a clinical treatment option.
Keywords: NSCLC; acquired resistance; collagens; immunotherapy; physical barrier.