Phase I clinical trial of the intraperitoneal (IP) administration of a novel nanoparticle formulation of paclitaxel (NTX).

Abstract

2558 Background: IP therapy is an attractive option for patients with IP carcinomatosis as many of these malignancies remain confined IP. Agents whose plasma clearance rates substantially exceed their rates of uptake from the peritoneal cavity are especially suited for IP administration. Pre-clinical studies of a novel formulation of nanoparticulate paclitaxel in animal tumor models demonstrated superior activity and substantially reduced systemic toxicity. This allowed for significant IP doses and concentrations, yet yielded very low systemic concentrations of paclitaxel. We report here the results of a Phase I trial of IP administered NTX. Methods: Patients (ECOG≤2) had relapsed, treatment refractory solid IP tumors and adequate organ function. NTX was administered IP as a bolus injection after 500 ml saline followed by IP administration of up to 2 L of saline. We utilized an accelerated dose escalation scheme until one DLT occurred during cycle 1, followed by a standard dose escalation (3+3 design) based on CTCAE V3 toxicities. The pharmacokinetics of IP administered NTX were characterized in plasma and ascites fluid. Secondary objectives were to define the recommended phase 2 dose of NTX, and characterize preliminary activity and toxicity. Results: 20 patients were treated at dose levels from 50 – 275 mg/M2 q 28 days. Primary malignancy was ovarian cancer (74%). Treatment was well tolerated at all dose levels. Common toxicities potentially related to NTX were: gastrointestinal (68%), constitutional (42%), and pain (42%). Average number of cycles received was 2 (range 1 to 6). Best response was stable disease (4 patients, 21%). Median length of disease stability was 99 days (range 85 to 151 days); median time on study patients with stable disease was 313 days (range 142 to 740 days). All Cmax in plasma were less than 35 ng/mL, with ascites fluid Cmax generally greater than 1000 ng/mL. Conclusions: IP NTX is well tolerated. MTD has not yet been reached. Pharmacokinetic data demonstrate significant, persistent IP exposure to paclitaxel with minimal systemic exposure. Accrual at the 275 mg/M2 dose level continues; updated results will be presented. Further clinical development of NTX is indicated. Clinical trial information: NCT00666991.