RESUMO
Chimeric antigen receptor (CAR)-modified immune cells have emerged as a promising approach for cancer treatment, but single-target CAR therapy in solid tumors is limited by immune escape caused by tumor antigen heterogeneity and shedding. Natural killer group 2D (NKG2D) is an activating receptor expressed in human NK cells, and its ligands, such as MICA and MICB (MICA/B), are widely expressed in malignant cells and typically absent from healthy tissue. NKG2D plays an important role in anti-tumor immunity, recognizing tumor cells and initiating an anti-tumor response. Therefore, NKG2D-based CAR is a promising CAR candidate. Nevertheless, the shedding of MICA/B hinders the therapeutic efficacy of NKG2D-CARs. Here, we designed a novel CAR by engineering an anti-MICA/B shedding antibody 1D5 into the CAR construct. The engineered NK cells exhibited significantly enhanced cytotoxicity against various MICA/B-expressing tumor cells and were not inhibited by NKG2D antibody or NKG2D-Fc fusion protein, indicating no interference with NKG2D-MICA/B binding. Therefore, the developed 1D5-CAR could be combined with NKG2D-CAR to further improve the obstacles caused by MICA/B shedding.
Assuntos
Neoplasias , Receptores de Antígenos Quiméricos , Humanos , Linhagem Celular Tumoral , Antígenos de Histocompatibilidade Classe I/imunologia , Antígenos de Histocompatibilidade Classe I/metabolismo , Células Matadoras Naturais , Neoplasias/imunologia , Neoplasias/metabolismo , Subfamília K de Receptores Semelhantes a Lectina de Células NK/genética , Subfamília K de Receptores Semelhantes a Lectina de Células NK/metabolismo , Receptores de Antígenos Quiméricos/genética , Receptores de Antígenos Quiméricos/metabolismo , Imunoterapia Adotiva/métodosRESUMO
Chimeric antigen receptor (CAR)-modified T and NK cell immunotherapy is a promising approach for cancer treatment. Due to the lack of tunability in anti-tumor activity, conventional CAR therapies have limited efficacy at low tumor antigen densities. To tune the CAR response to tumor cell surface antigens, we have developed a split CAR using the SpyCatcher-SpyTag system. The SpyCatcher serves as the ectodomain to constitute a SpyCatcher-CAR (SpyCAR), while SpyTag is attached to the antibodies that recognize tumor antigens. With dimerization mediated by SpyCatcher and SpyTag, the number and activation level of SpyCARs recruited by tumor antigens depends on the SpyTag number in the "antibody-SpyTag" fusion protein. The results demonstrated that the increasing number of SpyTags effectively enhanced the cytotoxicity of SpyCAR-NK92 cells against target cells. The development of SpyCAR with tunable cytotoxicity provides a novel strategy for CAR-based tumor immunotherapies.