Esterase-activatable β-lapachone prodrug micelles for NQO1-targeted lung cancer therapy

Lung cancer is one of the most lethal forms of cancer and current chemotherapeutic strategies lack broad specificity and efficacy. Recently, β-lapachone (β-lap) was shown to be highly efficacious in killing non-small cell lung cancer (NSCLC) cells regardless of their p53, cell cycle and caspase status. Pre-clinical and clinical use of β-lap (clinical form, ARQ501 or 761) is hampered by poor pharmacokinetics and toxicity due to hemolytic anemia. Here, we report the development and preclinical evaluation of β-lap prodrug nanotherapeutics consisting of diester derivatives of β-lap encapsulated in biocompatible and biodegradable poly(ethylene glycol)-b-poly(d,l-lactic acid) (PEG-b-PLA) micelles. Compared to the parent drug, diester derivatives of β-lap showed higher drug loading densities inside PEG-b-PLA micelles. After esterase treatment, micelle-delivered β-lap-dC₃ and -dC₆ prodrugs were converted to β-lap. Cytotoxicity assays using A549 and H596 lung cancer cells showed that both micelle formulations maintained NAD(P)H:quinone oxidoreductase 1 (NQO1)-dependent cytotoxicity. However, antitumor efficacy study of β-lap-dC₃ micelles against orthotopic A549 NSCLC xenograft-bearing mice showed significantly greater long-term survival over β-lap-dC₆ micelles or β-lap-HPβCD complexes. Improved therapeutic efficacy of β-lap-dC₃ micelles correlated with higher area under the concentration-time curves of β-lap in tumors, and enhanced pharmacodynamic endpoints (e.g., PARP1 hyperactivation, γH₂AX, and ATP depletion). β-Lap-dC₃ prodrug micelles provide a promising strategy for NQO1-targeted therapy of lung cancer with improved safety and antitumor efficacy.