Chimeric antigen receptor T cells engineered to recognize the P329G-mutated Fc part of effector-silenced tumor antigen-targeting human IgG1 antibodies enable modular targeting of solid tumors.

BACKGROUND

Chimeric antigen receptor (CAR) T cell therapy has proven its clinical utility in hematological malignancies. Optimization is still required for its application in solid tumors. Here, the lack of cancer-specific structures along with tumor heterogeneity represent a critical barrier to safety and efficacy. Modular CAR T cells indirectly binding the tumor antigen through CAR-adaptor molecules have the potential to reduce adverse events and to overcome antigen heterogeneity. We hypothesized that a platform utilizing unique traits of clinical grade antibodies for selective CAR targeting would come with significant advantages. Thus, we developed a P329G-directed CAR targeting the P329G mutation in the Fc part of tumor-targeting human antibodies containing P329G L234A/L235A (LALA) mutations for Fc silencing.

METHODS

A single chain variable fragment-based second generation P329G-targeting CAR was retrovirally transduced into primary human T cells. These CAR T cells were combined with IgG1 antibodies carrying P329G LALA mutations in their Fc part targeting epidermal growth factor receptor (EGFR), mesothelin (MSLN) or HER2/neu. Mesothelioma, pancreatic and breast cancer cell lines expressing the respective antigens were used as target cell lines. Efficacy was evaluated in vitro and in vivo in xenograft mouse models.

RESULTS

Unlike CD16-CAR T cells, which bind human IgG in a non-selective manner, P329G-targeting CAR T cells revealed specific effector functions only when combined with antibodies carrying P329G LALA mutations in their Fc part. P329G-targeting CAR T cells cannot be activated by an excess of human IgG. P329G-directed CAR T cells combined with a MSLN-targeting P329G-mutated antibody mediated pronounced in vitro and in vivo antitumor efficacy in mesothelioma and pancreatic cancer models. Combined with a HER2-targeting antibody, P329G-targeting CAR T cells showed substantial in vitro activation, proliferation, cytokine production and cytotoxicity against HER2-expressing breast cancer cell lines and induced complete tumor eradication in a breast cancer xenograft mouse model. The ability of the platform to target multiple antigens sequentially was shown in vitro and in vivo.

CONCLUSIONS

P329G-targeting CAR T cells combined with antigen-binding human IgG1 antibodies containing the P329G Fc mutation mediate pronounced in vitro and in vivo effector functions in different solid tumor models, warranting further clinical translation of this concept.

Informations de copyright

© Author(s) (or their employer(s)) 2022. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.

Déclaration de conflit d'intérêts

Competing interests: SS, M-RB and A-KK declare that they have no competing interests. DD and CJ declare previous employment and patents with Roche (Switzerland). DD declares current employment, patents, and stock ownership with Innovent Biologics (China) and CJ declares current employment, patents and ownership interest in Athebio AG (Switzerland). K-GS, JB, AF-G, EM, PU and CK declare employment, patents, and stock ownership with Roche (Switzerland). MS received honoraria from AMGEN, BMS, Janssen, Kite/Gilead, Roche, Novartis, Pfizer, Celgene and Takeda. MS received research support from AMGEN, BMS, Janssen, Kite/Gilead, Miltenyi, MorphoSys, Novartis, Roche and Seattle Genetics for work unrelated to the manuscript. MS declare consultancy for AMGEN, Celgene, Janssen, Kite/Gilead, Novartis, and Takeda. SK has received honoraria from TCR2 Inc., Novartis, BMS and GSK. SK and SE are inventors of several patents in the field of immuno-oncology. SK and SE received license fees from TCR2 Inc. and Carina Biotech. SK and SE received research support from TCR2 Inc., Tabby Therapeutics and Arcus Bioscience for work unrelated to the manuscript. P329G-CAR© is a trademark by Roche (Switzerland) and being developed by Roche (Switzerland) and by Innovent Biologics (China).