Abstract 4077: Dual-targeted CAR-NK cell therapy: optimized CAR design to prevent antigen escape and elicit a deep and durable response in multiple myeloma

Abstract Introduction: Multiple myeloma (MM) is an incurable hematologic malignancy and new strategies that offer a chance of obtaining long-term progression free survival are urgently needed. MM is associated with profound immune alterations and dysfunction of natural killer (NK) cells have been demonstrated to be crucial factors in MM progression. Myeloma cells are susceptible to killing by natural killer (NK) cells but acquire the ability to elude NK cell surveillance by avoiding recognition and suppressing NK cell function. Given the role of NK cells in the pathogenesis of MM, interest in harnessing NK cells to treat the cancer has been energized by the remarkable success of other adoptive cell therapies such as chimeric antigen receptor (CAR)-T cells. However, relapses associated with residual low-to-negative BCMA-expressing MM cells have been reported, necessitating the identification of additional targets. GPRC5D, expressed on MM cells from primary marrow samples with a distribution independent of BCMA. Methods: To prevent BCMA-antigen escape and elicit a deeper and more durable response in MM, we developed a new multiplexed edited NK cell configuration to restore anti-myeloma NK cell immunity, consisting of anti-BCMA VHH and anti-GPRC5D VHH antibodies, NKG2D and 2B4 co-stimulation signaling domains, and IL-15. Results: Dual targeting BCMA/GPRC5D CAR-NK showed potent in vitro killing of both BCMA+ and GPRC5D+ myeloma cells. Utilizing a repeated rounds of cancer cell clearance assay, BCMA/GPRC5D CAR NK cells showed remarkable persistence and antigen-mediated expansion of CAR-NK cells after more than 4 rounds of tumor cell re-challenges. Moreover, in comparison with single targeted BCMA CAR-NK cells, Dual targeting BCMA/GPRC5D CAR-NK cells effectively lysed BCMA negative target cells. In addition, in BCMA-antigenic escape model, it achieved more sustained tumor control than single targeting BCMA CAR-NK cells. PD-1/PD-L1 axis inhibition has been reported to enhance NK cell activity against MM cells by augmenting NK cell trafficking, immune complex formation, and cytotoxicity against PD-L1-expressing MM cells. We also demonstrated that combination of BCMA/GPRC5D CAR-NK with anti-PDL1-IL15 also showed more persistent tumor control. Conclusions: Our studies demonstrate the development of dual targeting BCMA/GPRC5D CAR NK cells may represent a highly effective off-the-shelf therapeutic product as a monotherapy or in combinations with other immune-regulating agents. Citation Format: Cuiqing Yang, Yifang Wang, Tingting Liu, Chao Wang, Huanyu Wang, Qingyang Wang, Qin Wang, Gang Ye, Renhong Tang, Zhuoxiao Cao. Dual-targeted CAR-NK cell therapy: optimized CAR design to prevent antigen escape and elicit a deep and durable response in multiple myeloma. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4077.