Phase II study of NK105, a paclitaxel-incorporating micellar nanoparticle, for previously treated advanced or recurrent gastric cancer

Purpose NK105 is a new drug delivery system formulation for paclitaxel (PTX) whose recommended dose (RD)　is 150 mg PTX equivalent/m² administered every 3 weeks, as determined in a phase I trial. This study aimed to evaluate the efficacy and safety of NK105 in patients with advanced gastric cancer after failure of first-line chemotherapy. Experimental design Eligible patients had measurable disease and one chemotherapeutic regimen except taxane. NK105 (150 mg PTX equivalent/m²) was administered by a 30-minute intravenous infusion every 3 weeks without anti-allergic premedication until disease progression, unacceptable toxicity or patient refusal. The primary efficacy endpoint was best overall response rate (ORR) post baseline. The secondary endpoints were progression-free survival (PFS), time to treatment failure (TTF) and overall survival (OS). All adverse events were reported using CTCAE v3.0. Results Between November 2007 and July 2009, 57 patients were enrolled and 56 were evaluable for efficacy. Two complete responses and 12 partial responses were observed for an ORR of 25%. The median PFS was 3.0 months, the median TTF was 2.8 months, and the median OS was 14.4 months. Drug related toxicity was mainly mild (grades 1–2) to severe (grades 3–4); other data: neutropenia (64.9%); leukopenia (17.5%); lymphopenia (8.8%); neuropathy-sensory (1.8%); fatigue (3.5%); and stomatitis (1.8%). There were no treatment-related deaths. Conclusions This study of NK105 (150 mg PTX equivalent/m²) proves the concept for the modest activity and tolerability of a new drug delivery system formulation for PTX. A phase III trial will be evaluated to clarify survival benefit.