Selumetinib in paediatric patients with BRAF-aberrant or neurofibromatosis type 1-associated recurrent, refractory, or progressive low-grade glioma: a multicentre, phase 2 trial

BACKGROUND: Pediatric low-grade glioma (pLGG) is the most common central nervous system tumor of childhood. Although overall survival is very good, many children suffer from multiple progressions and functional morbidities. There is no one universally accepted therapy for children with recurrent disease, however, standard cytotoxic chemotherapies are often utilized by most practitioners. The Pediatric Brain Tumor Consortium conducted a multi-institutional phase II study evaluating selumetinib (AZD6244, ARRY-142886), a MAP/ERK Kinase I/II inhibitor, in patients with recurrent, refractory or progressive pLGG assigned to numerous strata. The aim of the study was to evaluate the efficacy of selumetinib in these patients. METHODS: Eligibility required age 3–21 y/o, a Lansky or Karnofsky performance score greater than 60 and the presence of recurrent, refractory or progressive pLGG after at least one standard therapy. Stratum 1 included children with World Health Organization (WHO) grade I pilocytic astrocytoma (PA) harboring either one of the two most common BRAF aberrations (KIAA1549-BRAF fusion or the BRAF(V600E) mutation). Stratum 3 included children with any neurofibromatosis type 1 (NF1)-associated pLGG (WHO grades I and II). Selumetinib was provided as capsules given orally at the recommended phase II dose of 25 mg/m(2) twice daily. The primary endpoint was stratum-specific objective response rate assessd by the local site and sustained for at least 8 weeks. All responses were reviewed centrally and statistical analyses were done as per protocol. Although the trial (NCT01089101) is still ongoing in other strata, enrollment and planned follow-up is compete on both strata 1 and 3. FINDINGS: Between July 25, 2013, and June 12, 2015, 25 eligible and evaluable children were accrued to stratum 1, and between August 28, 2013, and June 25, 2015, 25 eligible and evaluable children were accrued to stratum 3. On stratum 1, 9/25 (36%) patients achieved a partial response (PR). The median follow-up for the 11 patients who have not yet experienced an event is 36.4 months (4.4–50.5; IQR=23.9). On stratum 3, 10/25 (40%) patients achieved a PR with a median follow-up of 48.6 months (8.6–59.1; IQR=12.2) for the 17 subjects without progressions. All patients evaluable for visual acuity had improved or stable vision. The most common attributable toxicities on both strata were grade 1 and 2 CPK elevation, hypoalbuminemia, dyspnea, rash, duodenal ulcer, anemia, dry skin, fatigue and diarrhea. Rare grade 3 toxicities included elevated CPK (n=5), maculopapular rash (n=5), neutropenia (n=3), nausea (n=3), paronychia (n=3), acneiform rash (n=2), diarrhea (n=2), elevated ALT (n=1), decreased ejection fraction (n=1), gastric hemorrhage (n=1), headache (n=1), skin infection (n=1), tooth infection (n=1) and weight gain (n=1). There was only one grade 4 toxicity, lymphopenia. There were no treatment-realted deaths. Patient reported outcomes and quality of life assessments were not part of the current study. INTERPRETATION: Selumetinib is active against recurrent, refractory or progressive PA harboring common BRAF aberrations and NF1-associated pLGG. To our knowledge, this is one of the first prospectively tested and successful molecularly-targeted agents in pLGG. These data not only provide an alternative to standard chemotherapy for these subgroups of patients, but this success has led to an interest in exploring efficacy in patients as a first-line therapy. In fact, these data have directly led to the development of two Children’s Oncology Group phase III studies in newly diagnosed pLGG patients both with and without NF1 comparing standard chemotherapy to selumetinib. The current trial was funded by a National Cancer Institute (NCI) Cancer Therapy Evaluation Program (CTEP) PBTC U01 Grant: 2UM1CA081457 (UM1) and by the American Lebanese Syrian Associated Charities.