由两种临床获批药物控制的双重 ON/OFF 开关嵌合抗原受体

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. , CD3 ) 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 (IFN ) 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 iON -CAR, down-regulated by lenalidomide within 4 to 6 for functionally inactive T cells (no IFN 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 iON -CAR T cells may alleviate exhaustion and hence augment persistence and long-term tumor control in patients.