Chemoembolizing hepatocellular carcinoma with microsphere cored with arsenic trioxide microcrystal

Chemoembolization for hepatocellular carcinoma (HCC) is often suboptimal due to multiple involved signaling and lack of effective drugs. Arsenic trioxide (ATO) is a potent chemotherapeutic agent, which can target multiple signaling and have substantial efficacy on HCC. However, its usage is limited due to systemic toxicity. Using ATO-eluting beads/microspheres for chemoembolization can have locoregional drug delivery and avoid systemic exposure but will require high drug load, which has not been achieved due to low solubility of ATO. Through an innovative approach, we generated the transiently formed ATO microcrystals via micronization and stabilized these microcrystals by solvent exchange. By encapsulating ATO microcrystals, but not individual molecules, with poly(lactide-co-glycolic acid) (PLGA), we developed microspheres cored with extremely high dense ATO. The molar ratio between ATO and PLGA was 157.4:1 and drug load was 40.1%, which is 4-20 fold higher than that of reported ATO nano/microparticles. These microspheres sustainably induced reactive oxygen species, apoptosis, and cytotoxicity on HCC cells and reduced tumor growth by 80% via locoregional delivery. Chemoembolization on mice model showed that ATO-microcrystal loaded microspheres, but not ATO, inhibited HCC growth by 60-75%, which indicates ATO within these microspheres gains the chemoembolizing function via our innovative approach.