Development of polymer micelles comprising an alkenylboronic acid pinacol ester as boron agents for BNCT.

Due to the fact that it minimizes invasiveness, boron neutron capture therapy (BNCT) may be one of the most elegant cancer therapies. To predict and maximize the therapeutic benefit of BNCT, it is necessary to enhance the deliverability of boron agents toward tumor tissues. Moreover, enhancing traceability for evaluating peak tumor accumulation and tumor-to-normal tissue ratios, which contribute to the estimation of therapeutic efficacy from BNCT, is also highly beneficial in the development of boron agents. In this paper we demonstrate the applicability of a polymer micelle system comprising alkenylboronic acid pinacol ester as a boron agent for BNCT. This micelle system exhibited a 13.3-fold increase in BNCT activity relative to a clinically available boron agent, L-BPA/fructose complex, which is used against murine squamous cell carcinoma (SCCVII). Moreover, polymer micelles may provide a nanospace to encapsulate activatable near-infrared/red fluorophores or indocyanine green contrast agents. Finally, tumor accumulation was visualized via the EPR effect using the in vivo imaging system described here.