Novel organic arsenic molecule darinaparsin: Development of IV and oral forms

Abstract

8501 Background: Darinaparsin (ZIO-101) is a novel organic arsenical active against diverse cancers in vitro, and in vivo. Darinaparsin i.v. activity in lymphoma is being evaluated in a phase II study. Darinaparsin is orally bioavailable; the oral form is being investigated in two phase I studies in patients with advanced malignancies. Methods: Phase II trial is being conducted in patients diagnosed with advanced lymphomas who had ≥ 1 prior therapy. Patients receive 300 mg/m2/day of darinaparsin i.v. for 5 consecutive days every 28 days. Efficacy and safety are evaluated by standard criteria. Phase I oral dose escalation studies are being conducted in patients with advanced malignancies and explore safety, MTD, DLTs and preliminary efficacy of continuous and intermittent dosing schedules. Starting continuous dose is 100 mg BID for 3 weeks with 1 week rest, starting intermittent dose is 300 mg twice weekly for 3 weeks followed by 1 week rest. Results: The phase II study has accrued 28 lymphoma patients (21 non-Hodgkin's, 7 Hodgkin's); median age at baseline 61 years, ECOG ≤2, median number of prior therapies 3. Seventeen subjects have received at least 2 cycles of darinaparsin and are evaluable for efficacy. Of these, 1 subject (PTCL) has achieved a complete response, 3 - partial responses (2 marginal zone, 1 Hodgkin's), and 4 stable disease (2 PTCL, 1 DLBCL, 1 Hodgkin's). A total of 63 cycles of darinaparsin have been administered to subjects with lymphoma. No Gr. 3 or higher drug-related AEs were reported. Two SAEs were considered possibly drug-related (fall; neutropenic fever). Phase I studies accrued 35 patients; median age at baseline 58 years, ECOG ≤2, median number of prior therapies 3. Predominant tumor types include: colorectal (17), pancreatic (3), NHL (3). Current darinaparsin dose levels: continuous 200 mg BID, 2× weekly 900 mg. Of 18 patients evaluable for efficacy, 10 demonstrate SD ≥ 3 cycles. Oral darinaparsin bioavailability is 58%. Drug-related AEs include nausea/vomiting, fatigue, decreased appetite/anorexia. Conclusions: Darinaparsin is active in heavily pretreated patients with advanced lymphoma and has been very well tolerated. Oral darinaparsin is also well tolerated, and shows early activity. [Table: see text]