First-in-human phaseⅠstudy of JPH203 in patients with advanced solid tumors.

Abstract

419 Background: Uptake of amino acids is essential for cancer growth. L-type amino acid transporter-1 (LAT-1) is overexpressed in various cancers, and uptake of LAT-1 substrate amino acids is known to have a critical role in cancer growth. JPH203 is a novel, selective, LAT-1 inhibitor. A first-in-human phase I study of JPH203 was designed to determine the safety, maximum-tolerated dose (MTD) and recommended dose. This study included evaluation of the anti-tumor effect, pharmacokinetics, and pharmacodynamics of JPH203 and analyzed plasma free amino acids. Methods: JPH203 was administered intravenously for 7 days followed by 21 days’ rest at planned doses ranging from 12 to 110 mg/m2 in patients with advanced solid tumors refractory to standard therapy. Before starting this schedule, we confirmed safety of a single dose of JPH203. Dose-limiting toxicity was evaluated during the first cycle, using a 3+3 design. Results: 17 patients were enrolled from January 2015 to August 2016. One patient was discontinued after a single dose of JPH203 because of tumor progression. Dosage was escalated up to 85 mg/m2. Grade 3 liver dysfunction occurred in 1 of 6 patients at 60 mg/m2 and in the first patient at 85 mg/m2. Therefore, it was determined that MTD was 60 mg/m2. Common treatment-related adverse events were increased ALT/AST, malaise, nausea, hypertension and fever of Grade 1 or 2. Partial response was achieved in a patient with biliary tract cancer (BTC) who continued JPH203 for two years without progression. Disease control (PR+SD) was observed in 3 of 5 patients with BTC and 2 of 6 with colorectal cancer. LAT-1 substrate amino acids and branched chain amino acids including LAT-1 substrate amino acids were higher in patients with BTC than in those with other cancers. All patients with disease control had a body mass index more than the median of 20.5 kg/m2. In exploratory analysis, longer survival was achieved in patients with high inhibition of uptake of LAT-1 substrate amino acids, compared with patients with low inhibition of uptake. Conclusions: JPH203 was well tolerated, resulting in promise against BTC. This phase I study suggested that LAT-1 could be targeted in treatment for advanced BTC, because LAT-1 substrate amino acids in plasma tended to remain high. Clinical trial information: UMIN000016546.