Phase II Study of oral capsular 4-hydroxyphenylretinamide (4-HPR/fenretinide) in pediatric patients with refractory or recurrent neuroblastoma: A report from the Children's Oncology Group

Abstract

Purpose: To determine the response rate to oral capsular fenretinide in children with recurrent or biopsy proven refractory high-risk neuroblastoma. Experimental Design: Patients received 7 days of fenretinide: 2475 mg/m2/day divided TID (<18 years) or 1800 mg/m2/day divided BID (≥18 years) every 21 days for a maximum of 30 courses. Patients with stable or responding disease after course 30 could request additional compassionate courses. Best response by course 8 was evaluated in Stratum 1 (measurable disease on CT/MRI +/- bone marrow and/or MIBG avid sites) and Stratum 2 (bone marrow and/or MIBG avid sites only). Results: Sixty-two eligible patients, median age 5 years (range 0.6-19.9), were treated in Stratum 1 (n=38) and Stratum 2 (n=24). One partial response (PR) was seen in Stratum 2 (n=24 evaluable). No responses were seen in Stratum 1 (n=35 evaluable). Prolonged stable disease (SD) was seen in 7 patients in Stratum 1 and 6 patients in Stratum 2 for 4-45+ (median 15) courses. Median time to progression was 40 days (range 17-506) for Stratum 1 and 48 days (range 17-892) for Stratum 2. Mean 4-HPR steady state trough plasma concentrations were 7.25 μM (coefficient of variation 40-56%) at day 7 course 1. Toxicities were mild and reversible. Conclusions: Although neither stratum met protocol criteria for efficacy, 1 PR + 13 prolonged SD occurred in 14/59 (24%) of evaluable patients. Low bioavailability may have limited fenretinide activity. Novel fenretinide formulations with improved bioavailability are currently in pediatric Phase I studies.