Toxicological profile and safety pharmacology of a single dose of fibroblast activation protein-α-based doxorubicin prodrug: in-vitro and in-vivo evaluation.

Fibroblast activation protein-α (FAPα) is a promising tumor-associated target expressed by reactive stromal fibroblasts in tumor tissue. FAPα has a postprolyl peptidase activity and can specifically cleave N-terminal benzyloxycarbonyl (Z)-blocked peptides, such as the substrate Z-Gly-Pro-AMC. Doxorubicin (DOX) is an effective antitumor drug, but its application is greatly limited by toxic adverse effects owing to poor tumor selectivity. Based on these facts, we previously designed a FAPα-targeting prodrug of doxorubicin (FTPD) which can be selectively hydrolyzed by FAPα. FTPD can retain potent antitumor efficacy and has favorable tumor targeting. The present study aimed to further evaluate the toxicological profile and the safety pharmacological property of FTPD in vitro and in vivo. The cytotoxicity assay showed that FTPD displayed markedly lower cytotoxicity to 3T3 cells and HEK-293 cells compared with DOX. In the short-term toxicity study, mice treated with 25 mg/kg of FTPD showed no obvious change in the appearance and general behavior, and no case of mortality was observed within 14 days. Unlike DOX, FTPD exhibited reduced toxicity to heart, liver, kidney, spleen as well as peripheral white blood cells in mice. Moreover, open file test and general pharmacology study were also conducted correspondingly in mice and beagle dogs. It was found that FTPD may not produce significant pharmacological effects on spontaneous locomotor activity and cardiovascular-respiratory system except for a transient decreasing in systolic blood pressure. Taken together, the results of this work suggest that FTPD has more favorable toxicological profile and better drug safety compared with its parent drug DOX.