Despite growing interest in targeted cancer therapy with small molecule drug conjugates (SMDCs), the short half-life of these conjugates in blood associated with their small size has limited their efficacy in cancer therapy. In this report, we propose a new approach for improving the antitumor efficacy of SMDCs based on nanoparticle-assisted delivery. Ideally, a nanoparticle-based delivery vehicle would prolong the half-life of an SMDC in blood and then release it in response to stimuli in the tumor microenvironment (TME). In this study, PEGylated bilirubin-based nanoparticles (BRNPs) were chosen as an appropriate delivery carrier because of their ability to release drugs in response to TME-associated reactive oxygen species (ROS) through rapid particle disruption. As a model SMDC, ACUPA-SN38 was synthesized by linking the prostate-specific membrane antigen (PSMA)-targeting ligand, ACUPA, to the chemotherapeutic agent, SN38. ACUPA-SN38 was loaded into BRNPs using a film-formation and rehydration method. The resulting ACUPA-SN38@BRNPs exhibited ROS-mediated particle disruption and rapid release of the SMDC, resulting in greater cytotoxicity toward PSMA-overexpressing prostate cancer cells (LNCaP) than toward ROS-unresponsive ACUPA-SN38@Liposomes. In a pharmacokinetic study, the circulation time of ACUPA-SN38@BRNPs in blood was prolonged by approximately 2-fold compared with that of the SMDC-based micellar nanoparticles. Finally, ACUPA-SN38@BRNPs showed greater antitumor efficacy in a PSMA-overexpressing human prostate xenograft tumor model than SN38@BRNPs or the SMDC alone. Collectively, these findings suggest that BRNPs are a viable delivery carrier option for various cancer-targeting SMDCs that suffer from short circulation half-life and limited therapeutic efficacy.
Bibliographical noteFunding Information:
This research was supported by the Global Research Laboratory (GRL) Program (NRF-2012K1A1A2045436) and the Bio & Medical Technology Development Program (NRF-2018M3A9B5023527) through the National Research Foundation of Korea (NRF) funded by the Ministry of Science and ICT and the Korea Health Technology R&D Project (Grant No. HI13C21810301) through the Korea Health Industry Development Institute (HHIDI) funded by the Ministry of Health & Welfare, Republic of Korea.
© 2018 American Chemical Society.