Abstract 1368: Preclinical evaluation of NC-6201, an antibody/drug-conjugated micelle incorporating novel hemiasterlin analogue E7974

Abstract

Abstract Background: Antibody-drug conjugates (ADCs) have been recognized as a promising anticancer agent. There have been a lot of registered clinical trials for ADCs. However, not all ADC compounds were successful. To overcome the difficulties and drive the next generation of ADCs, we have recently developed Antibody/Drug-Conjugated Micelle (ADCM) system. ADCM is composed of polyethylene glycol-poly (amino acid derivative) polymers, which can form a micellar nanoparticle spontaneously in aqueous media with a diameter of 20-100 nm. Antibodies are attached to the surface of the nanoparticle, while payloads are incorporated in the inner core at a payload-to-antibody molecular ratio of 100-200. In this study, anti-EGFR monoclonal antibody NCAB001 and novel hemiasterlin analogue E7974 were used as a targeting sensor and a payload of the ADCM (NC-6201), respectively. Here we report the results of in vitro evaluation and in vivo efficacy and toxicity studies. Methods: NC-6201 was prepared as described previously (Japan Patent No.4538666) with slight modification. The antigen affinity and the cytotoxicity of NC-6201 were evaluated using a Biacore system and Cell Counting Kit-8, respectively. NC-6201 was administered intravenously to BALB/c-nu/nu mice xenografted with various human tumor cell lines. Tumor volumes and animal body weights were monitored 2 or 3 times a week. Also, the dose- and schedule-dependency of the antitumor effect were evaluated. Single-dosed toxicological studies of NC-6201 in SD rats and cynomolgus monkeys were performed. Results: NC-6201 showed similar antigen affinity to the unconjugated NCAB001 and had a broad range of in vitro cytotoxicity against a panel of tumor cells. NC-6201 potently suppressed tumor growth in nude mice bearing subcutaneous human tumor xenografts expressing EGFR, such as BxPC-3 (pancreas) and MDA-MB-231 (triple-negative breast) tumor models. The efficacious NC-6201 dose schedules were achieved at one tenth or two fifth of its MTD. In an EGFR-null tumor model, NC-6201 and untargeted micelle incorporating E7974 showed comparable tumor growth inhibition. Overall, NC-6201 at efficacious doses was well tolerated without significant body weight loss, indicating that NC-6201 has an excellent therapeutic window. Relative to E7974, NC-6201 showed an unaltered toxicity profile in rats and monkeys, and the potential for reduced toxicity and an improved therapeutic window. Conclusion: Based on these promising results, NC-6201 is advanced in our project pipeline as a clinical candidate for cancer therapy. Citation Format: Mitsunori Harada, Masami Tsuchiya, Ryusuke Miyazaki, Tadashi Inoue, Ryosuke Tanaka, Yuuki Yanagisawa, Masayoshi Ito, Yu Ito, Kenichiro Naito. Preclinical evaluation of NC-6201, an antibody/drug-conjugated micelle incorporating novel hemiasterlin analogue E7974. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1368.