Spatial transcriptomics data of RM9-hSTEAP1 tumor tissues treated with CAR-T cells

Immunosuppressive microenvironments, the lack of immune infiltration, and antigen heterogeneity pose challenges for chimeric antigen receptor (CAR)-T cell therapies applied to solid tumors. Previously, CAR-T cells were armored with immunostimulatory molecules, such as interleukin-12 (IL-12), to overcome this issue, but faced high toxicity. Here, we show that collagen-binding domain-fused IL-12 (CBD-IL-12) secreted from CAR-T cells to target human six transmembrane epithelial antigen of the prostate 1 (STEAP1) is retained within murine prostate tumors. This leads to high intratumoral interferon-γ levels, without hepatotoxicity and infiltration of T cells into non-target organs compared with unmodified IL-12. Both innate and adaptive immune compartments are activated and recognize diverse tumor antigens after CBD-IL-12-armored CAR-T cell treatment. Combination of CBD-IL-12-armored CAR-T cells and immune checkpoint inhibitors eradicated large tumors in an established prostate cancer mouse model. Additionally, human CBD-IL-12-armored CAR-T cells showed potent anti-tumor efficacy in an 22Rv1 xenograft while reducing circulating IL-12 levels compared with unmodified IL-12-armored CAR-T cells. CBD-fusion to potent payloads of CAR-T therapy may remove obstacles to their clinical translation towards elimination of solid tumors. NanoString GeoMx Digital Spatial Profiler (DSP) whole transcriptome analysis (WTA) was performed on RM9-hSTEAP1 tumor samples collected at 10 days after CAR-T cell treatment. PFA-fixed, paraffin embedded tumor blocks were sectioned, and Twelve regions of interest (ROI) were chosen across four different tumor sections in each treated group followed by library preparation and sequencing. A tumor sample in unarmored CAR-T treatment group was not used because the tissue section was damaged.