A phase I trial of pomalidomide for children with recurrent, progressive/refractory central nervous system (CNS) tumors: A Pediatric Brain Tumor Consortium (PBTC) study.

Abstract

10543 Background: CNS malignancies are the most common solid tumors among children. Novel therapies are needed to help improve the survival outcomes in children with recurrent disease. Pomalidomide is an immunomodulatory agent thought to also function through a combination of anti-angiogenic, anti-inflammatory and cytotoixic activity making it a good candidate to explore in pediatric CNS tumors. Methods: A Phase I trial of pomalidomide was conducted among children ≥ 3 to < 21 years old with recurrent, progressive/refractory CNS tumors using the “rolling 6” dose escalation design. The primary objective was to determine the maximum tolerated dose (MTD) and/or recommended Phase II dose (RP2D) when given orally once daily for 21 consecutive days of a 28-day course. Once the MTD was established, 12 additional patients were enrolled on expansion cohorts based on age and steroid use. Results: 29 children were enrolled and 25 were evaluable for dose limiting toxicity (DLT) evaluation. The MTD was 2.6 mg/m2 (Dose level 2). DLTs observed at dose level 3 (3.4 mg/m2) included diarrhea (n = 1), thrombocytopenia (n = 1) and lung infection (n = 1), all grade 3. The most common toxicities were grade 1 lymphopenia (55%), leukopenia (62%) and thrombocytopenia (38%). There were no obvious differences in tolerability based on age or steroid use. Pharmacokinetics were similar to those observed in adults and increased in a dose-dependent manner. At the RP2D of 2.6 mg/m2, the Cmax was 97.4 ng/mL and the t½ was 4.1 hours. The median number of treatment cycles was 1.6 (0.2-12.3). Two patients, one with an oligodendroglioma and one with anaplastic pleomorphic xanthoastrocytoma, had long term stable disease for 9 and 18+ cycles. No objective responses were observed. Twelve month progression-free and overall-survivals were 5.2+/-3.6% and 12.8+/-8.5%, respectively. Immunologic correlate analyses are ongoing. Conclusions: The RP2D of pomalidomide is 2.6 mg/m2 in children with recurrent brain tumors. Further prospective evaluation of this agent alone or in combination will be necessary to better understand its efficacy in specific pediatric CNS tumor populations. Clinical trial information: NCT02415153.