A phase II prospective study of selumetinib in children with recurrent or refractory low-grade glioma (LGG): A Pediatric Brain Tumor Consortium (PBTC) study.

Abstract

10504 Background: A greater understanding of the Ras-MAP kinase-signaling pathway in pediatric low-grade glioma (LGG) paired with the availability of potent selective inhibitors has enhanced the ability to target this pathway with therapeutic intent. Methods: The PBTC conducted a multi-institutional phase II study (NCT01089101) evaluating selumetinib (AZD6244, ARRY-142886), a MEK I/II inhibitor, in children with recurrent/refractory LGG assigned to 6 strata and treated at 25 mg/m2/dose PO BID for up to two years. Here we present the data from three of these strata. The remaining strata are still accruing patients. Results: Stratum I included children with non-NF-1 and non-optic pathway recurrent/refractory pilocytic astrocytoma (PA) harboring BRAF aberrations (BRAF V600e mutation or the BRAF-KIAA 1549 fusion). Eight of 25 (32%) patients achieved a partial response (PR) with 2-year PFS of 66+/-11%. Two of 7 (29%) patient tumors with a BRAF V600e mutation and 6/18 (33%) with a BRAF KIAA-1549 fusion had a PR. Stratum 3 enrolled NF-1-associated LGG. Tissue for tumor BRAF evaluation was not required for eligibility. Ten of 25 (40%) achieved PR with a 2-year PFS of 96+/-4%. Only one patient progressed while on treatment. Stratum 4 included children with non-NF-1 optic pathway/hypothalamic LGG. Tissue for tumor BRAF evaluation was not required for eligibility. Two of 16 (12.5%) had a PR with a 2-year PFS of 65+/-13%. The BRAF aberration status of the responders in strata 3 and 4 is mostly unknown. All responses were confirmed centrally and seven patients remain on treatment. The most common toxicities were grade 1/2 CPK elevation, diarrhea, hypoalbuminemia, elevated AST and rash. Rare grade 3/4 toxicities included elevated CPK, rash, neutropenia, emesis and paronychia. Conclusions: Selumetinib was effective in treating children with recurrent/refractory LGG, including those with NF-1 associated LGG and PA harboring BRAF V600e mutation or BRAF-KIAA 1549 fusion. Larger prospective studies are necessary to determine the future, specific role of this agent in treating children with LGG harboring specific molecular aberrations. Clinical trial information: NCT01089101.