Abstract 2836: Genome engineered natural killer cell immunotherapy against osteosarcoma

Abstract Over the last decade Chimeric Antigen Receptor based T cell therapy (CAR-T) has developed into an effective immunotherapy for some cancers. Unfortunately, CAR-T cell therapies have several shortcomings and clinical success has primarily been limited to hematological cancers. Challenges of CAR-T cell therapy include tumor immune evasion through loss of target antigen expression by tumor cells and inhibition of CAR-T cell function by tumor expressed inhibitory molecules. Natural killer (NK) cells present an alternative to T cells that could be more effective due to their ability to perform both antigen dependent and independent killing. NK cells have demonstrated antigen specific killing when engineered to express CARs and NK cells also mediate the direct killing of transformed cells with reduced or absent MHC expression. Moreover, NK cells carry out antibody dependent cell mediated cytotoxicity (ACDD) of cells bound by antibodies via the NK cell CD16A receptor. Due to the multiple modalities for cancer cell killing, there is an increased interest in NK cells for cancer immunotherapy. As NK cells are not associated with graft versus host disease, neurotoxicity, long-term autoimmunity, nor cytokine release syndrome, they are more suited for use in allogeneic settings than T cells and have significant clinical potential for use as off-the-shelf products. However, previous publications and clinical trials have demonstrated that the use of unmanipulated NK cells to treat cancer is minimally effective, likely due to limited engraftment, little in vivo expansion or persistence, and suppression by the tumor microenvironment. NK cells activated and expanded with engineered feeder cells expressing membrane bound interleukin-21 (mbIL-21) and 4-1BBL have shown promising results clinically with high-risk myeloid malignancies and preclinically in several solid tumor models. Therefore, we hypothesize that activated/expanded CAR-NK cells that have been genetically edited can be used to successfully treat osteosarcoma, a disease for which patient outcome has not improved in over forty years. Our proposed objectives are to evaluate the baseline response of rested- and activated/expanded-NK cells against various osteosarcoma cell lines, knockout negative regulators of NK cell function (specifically, c-CBL, IL-1R8, and SMAD3), and implement several CARs alone or in combination that optimally activate NK cell antigen-specific killing. Genetically engineered CAR-NK cells will be evaluated for enhanced therapeutic efficacy and safety in osteosarcoma models. Our preliminary data strongly supports the hypothesis that CAR-NK cell-based cancer immunotherapy can be fully realized using activated, genome engineered CAR-NK cells. Citation Format: Gabrielle M. Robbins, Kenta Yamamoto, Joshua Krueger, Walker Lahr, Joseph Skeate, Branden Moriarity. Genome engineered natural killer cell immunotherapy against osteosarcoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2836.