Dual ON/OFF-switch chimeric antigen receptor controlled by two clinically approved drugs
Menée à l'aide de lignées cellulaires et d'un modèle murin de cancer de la prostate, cette étude met en évidence l'intérêt de lymphocytes CAR-T modifiés de manière à ce que leur activité puisse être régulée par deux médicaments (vénétoclax et lénalidomide) pour réduire le risque d'immunogénicité
T cells can be gene-modified with chimeric antigen receptors (CARs) to recognize and directly kill tumor cells. While CAR T cell therapy has been approved to treat some B cell malignancies, for nonhematological solid tumors toxicity and limited efficacy remain important obstacles. One approach to improve safety and T cell persistence is to incorporate an ON- or OFF-switch directly into the CAR that can be remotely regulated by administration of a small molecule. Here, we have developed an ON-CAR that can be induced by venetoclax as well as an all-in-one ON/OFF-CAR down-regulated by lenalidomide. Both of these small molecules are clinically approved and the switch components are of human origin thus reducing the risk of immunogenicity. The ability to remotely control the activity of chimeric antigen receptors (CARs) with small molecules can improve the safety and efficacy of gene-modified T cells. Split ON- or OFF-switch CARs involve the dissociation of tumor–antigen binding from T cell activation (i.e., CD3ζ) on the receptor (R-) and signaling (S-) chains, respectively, that either associate or are disrupted in the presence of a small molecule. Here, we have developed an inducible (i)ON-CAR comprising the anti-apoptotic B cell lymphoma protein 2 protein in the ectodomain of both chains which associate in the presence of venetoclax. We showed that inducible ON (iON)-CAR T cells respond to target tumors cells in the presence of venetoclax or the BH3 mimetic navitoclax in a dose-dependent manner, while there is no impact of the drugs on equivalent second generation-CAR T cells. Within 48 h of venetoclax withdrawal, iON-CAR T cells lose the ability to respond to target tumor cells in vitro as evaluated by Interferon-gamma (IFNγ) production, and they are reliant upon the presence of venetoclax for in vivo activity. Finally, by fusing a degron sequence to the endodomain of the iON-CAR S-chain we generated an all-in-one ON/OFF-switch CAR, the iONØ-CAR, down-regulated by lenalidomide within 4 to 6 for functionally inactive T cells (no IFNγ production) within 24 h. We propose that our remote-control CAR designs can reduce toxicity in the clinic. Moreover, the periodic rest of iON and iONØ-CAR T cells may alleviate exhaustion and hence augment persistence and long-term tumor control in patients.