J Med Chem. 2020 Sep 15. doi: 10.1021/acs.jmedchem.0c01232. Online ahead of print.
Vγ9/Vδ2 T-cells are activated by pyrophosphate-containing small molecules known as phosphoantigens (PAgs). The pres-ence of the pyrophosphate group in these PAgs has limited their drug-like properties due to its instability and polar nature. In this work, we report a novel and short Olefin Grubbs metathesis-mediated synthesis of methylene and difluoromethylene monophosphonate derivatives of the PAg (E)-4-hydroxy-3-methyl-but-2-enyl pyrophosphate (HMBP) as well as their aryloxy diester
phosphonamidate prodrugs, termed ProPAgens. These prodrugs showed excellent stability in human serum (t1/2 > 12 h) and potent activation of Vγ9/Vδ2 T-cells (EC50 ranging from 5 fM to 73 nM), which translated into sub-nanomolar γδ T-cell-mediated eradication of bladder cancer cells in vitro. Additionally, a combination of in silico and in vitro enzymatic assays demonstrated the metabolism of these phosphonamidates to release the unmasked the PAg monophosphonate species. Collectively, this work establishes HMBP monophosphonate ProPAgens as ideal candidates for further investigation as nov-el cancer immunotherapeutic agents.