Intraperitoneal infusion of NKG2D CAR-NK cells induces endogenous CD8+ T cell activation in patients with advanced colorectal cancer.

Peritoneal metastasis (PM) is a prevalent mode of metastasis in colorectal cancer (CRC) with rapid disease progression and limited treatment options. Locoregional infusion of immune cells have been explored in different types of solid tumors, but the feasibility and safety of locoregional chimeric antigen receptor-natural killer (CAR-NK) cells in treating CRC-PM is still unknown. We report the results of a phase 1 dose-escalation clinical trial (NCT05213195) using intraperitoneal infusion of NKG2D CAR-NK cells in heavily-pretreated patients with CRC-PM, and the immune-modulatory effect of CAR-NK cells was also illustrated using multi-omics analysis and functional validation. Locoregional NKG2D CAR-NK cell therapy showed preliminary efficacy and tolerable toxicity in this study. Of nine patients, three achieved stable disease, and the disease control rate was 33.3%. Notably, CD8⁺ T cells post CAR-NK infusion showed the enrichment of a subset co-expressing CD38 and human leukocyte antigen (HLA)-DR, which were highly clonal and also associated with a cytotoxic phenotype. This activated CD38⁺ HLA-DR⁺ T cell subset, together with their effector phenotype and function, was induced and maintained by the secretome of activated CAR-NK cells. Our data provide evidence supporting the feasibility of locoregionally infused CAR-NK cells to treat patients with CRC-PM, and indicate peripheral immune activation after locoregional CAR-NK therapy.