Abstract
BACKGROUND: Platelet-derived growth factor receptor (PDGFR) signaling has been directly implicated in pediatric high-grade gliomagenesis. This study evaluated the safety and tolerability of crenolanib, a potent, selective inhibitor of PDGFR-mediated phosphorylation, in pediatric patients with high-grade glioma (HGG). METHODS: We used a rolling-6 design to study the maximum tolerated dose (MTD) of once-daily crenolanib administered during and after focal radiation therapy in children with newly diagnosed diffuse intrinsic pontine glioma (DIPG) (stratum A) or with recurrent/progressive HGG (stratum B). Pharmacokinetics were studied during the first cycle at the first dose and at steady state (day 28). Alterations in PDGFRA were assessed by Sanger or exome sequencing and interphase fluorescence in situ hybridization or single nucleotide polymorphism arrays. RESULTS: Fifty evaluable patients were enrolled in the 2 strata, and an MTD of 170 mg/m(2) was established for both. Dose-limiting toxicities were primarily liver enzyme elevations and hematologic count suppression in both strata. Crenolanib AUC(0-48h) and C (MAX) did not differ significantly for crushed versus whole-tablet administration. Overall, PDGFRA alterations were observed in 25% and 30% of patients in stratum A and B, respectively. Neither crenolanib therapy duration nor survival outcomes differed significantly by PDGFRA status, and overall survival of stratum A was similar to that of historical controls. CONCLUSIONS: Children tolerate crenolanib well at doses slightly higher than the established MTD in adults, with a toxicity spectrum generally similar to that in adults. Studies evaluating intratumoral PDGFR pathway inhibition in biomarker-enriched patients are needed to evaluate further the clinical utility of crenolanib in this population.