pH driven precipitation of quisinostat onto PLA-PEG nanoparticles enables treatment of intracranial glioblastoma

Histone deacetylases (HDACs) are known to be key enzymes in cancer development and progression through their modulation of chromatin structure and the expression and post-translational modification of numerous proteins. Aggressive dedifferentiated tumors, like glioblastoma, frequently overexpress HDACs, while HDAC inhibition can lead to cell cycle arrest, promote cellular differentiation and induce apoptosis. Although multiple HDAC inhibitors, such as quisinostat, are of interest in oncology due to their potent in vitro efficacy, their failure in the clinic as monotherapies against solid tumors has been attributed to poor delivery. Thus, we were motivated to develop quisinostat loaded poly(D,L-lactide)-b-methoxy poly(ethylene glycol) nanoparticles (NPs) to test their ability to treat orthotopic glioblastoma. In developing our NP formulation, we identified a novel, pH-driven approach for achieving over 9% (w/w) quisinostat loading. We show quisinostat-loaded NPs maintain drug potency in vitro and effectively slow tumor growth in vivo, leading to a prolonged survival compared to control mice.