Cooperative armoring of CAR and TCR T-cells by T cell-restricted IL-15 and IL-21 universally enhances solid tumor efficacy

Chimeric antigen receptor (CAR) and T-cell receptor (TCR) T-cell therapies are effective in a subset of patients with solid tumors, but new approaches are needed to enhance efficacy and universally improve patient outcomes. IL-15 and IL-21 are common cytokine-receptor gamma chain family members with distinct, pleiotropic effects on T-cells and other lymphocytes. We found that self-delivery of these cytokines by CAR or TCR T-cells prevents functional exhaustion by repeated stimulation and limits the emergence of dysfunctional natural killer (NK)-like T-cells. Across different preclinical murine solid tumor models, we observe enhanced regression with each individual cytokine but the greatest anti-tumor efficacy when T-cells are armored with both. Thus, the co-expression of membrane-tethered IL-15 and IL-21 represents a technology to enhance the resilience and function of engineered T-cells against solid tumors and could be applicable to multiple therapy platforms and diseases. T cells from a 28-year-old donor were transduced to express E7-TCR (E7-TCR T cells). We compare E7-TCR T cells with either 1. Tethered IL15 or 2. Tethered IL15/IL21. These T cells were then exposed to continuous antigen (CAE) via CaSki cancer cells in vitro. Cancer cells were replenished Q2-4 days for a total of 14 tumor rechallenges. The samples were analyzed after manufacturing (no tumor exposure, Day0), after 5 exposures (Day12), and after 14 exposured (Day26) using single-cell sequencing. In each sample, we labeled the IL15 cells with TotalSeq-C0251, cat. no. 394661, barcode seq. GTCAACTCTTTAGCG; - IL15/21 cells TotalSeq-C0252, cat. no. 394663, barcode seq. TGATGGCCTATTGGG