A feeder cell-free activation and expansion strategy to generate memory-like NK cells sufficient for off-the-shelf multi-dose adoptive cell therapy.

Abstract Adoptive cell therapy (ACT) using NK cells is a promising armament in the fight against cancer. Cytokine induced memory like (CIML) NK cells have been shown in clinical studies to have potent antitumor activity with superior in vivo persistence. Currently, the expansion of NK cells for clinical development is mainly based on feeder cells, which imposes significant regulatory hurdles and increases the costs for manufacturing. We have developed fusion proteins, HCW9201 and HCW9206 comprising of IL-15/IL-18/IL-12 and IL15/IL-7/IL-21, respectively, capable of priming memory-like differentiation and expanding CIML NK cell products without using feeder cells. This “Kick and Expand” strategy allows greater than 100x expansion of CIML NK cells from donor PBMCs in as little as 14 days without the use of exogenous feeder cells. Continued expansion can yield sufficient CIML NK cells for cryopreservation and multiple ACT infusions. The NK cells generated have bona fide memory-like properties: enhanced antitumor activity across multiple cancer cell lines, higher metabolic capacity, stable epigenetic demethylation of the IFN-γ promoter and increased persistence in NSG mice, when compared to conventional NK cells. In conclusion, this “Kick and Expand” process supports generation of abundant CIML NK cells for multiple ACT infusions and provides simpler, more regulatory friendly, off-the-shelf platform for generating NK cell products, including those with chimeric antigen receptor (CAR) constructs.