Phase I studies of darinaparsin in patients with relapsed or refractory peripheral T-cell lymphoma: a pooled analysis of two phase I studies conducted in Japan and Korea

OBJECTIVE: Two phase I studies of darinaparsin including Japanese and Korean patients with relapsed/refractory peripheral T-cell lymphoma were performed to evaluate its safety (primary purpose), efficacy and pharmacokinetic profile (ClinicalTrials.gov: NCT01435863 and NCT01689220). METHODS: Patients received intravenous darinaparsin for 5 consecutive days at 200 mg/m(2)/day in 4-week cycles, 300 mg/m(2)/day in 4-week cycles or 300 mg/m(2)/day in 3-week cycles. RESULTS: Seventeen Japanese and 6 Korean patients were enrolled and treated. Drug-related adverse events developed in 18 patients (78%). Dose-limiting toxicity, grade 3 hepatic dysfunction, was reported on Day 15 of cycle 1 in 1 Japanese patient who received 300 mg/m(2)/day. The most common drug-related, grade ≥ 3 adverse events were lymphopenia (9%), neutropenia (9%) and thrombocytopenia (9%). No deaths occurred. In 14 evaluable patients, 1 and 3 patients had complete response and partial response, respectively. The plasma concentration-time profiles of arsenic, a surrogate marker for darinaparsin, were similar between Japanese and Korean patients. No significant difference was found in its pharmacokinetic profile. CONCLUSIONS: These data indicate the good tolerability and potential efficacy of darinaparsin in patients with relapsed/refractory peripheral T-cell lymphoma. Darinaparsin 300 mg/m(2)/day for 5 consecutive days in 3-week cycles is the recommended regimen for phase II study.