10152-PEDT-5 JAPANESE SUBGROUP ANALYSIS OF A PHASE II TRIAL OF DABRAFENIB PLUS TRAMETINIB (D+T) IN BRAF V600-MUTANT PEDIATRIC LOW-GRADE GLIOMA (PLGG) AND RELAPSED/REFRACTORY (R/R) BRAF V600-MUTANT PEDIATRIC HIGH-GRADE GLIOMA (PHGG)

Abstract

Abstract BACKGROUND pLGG is the most common pediatric brain cancer, and BRAF V600 mutation has been detected in ≈17% of cases. pHGGs comprise ≈10% of pediatric central nervous system tumors and are a leading cause of childhood cancer-related death. The result of a phase II global clinical trial (NCT02684058) of D+T vs carboplatin + vincristine (C+V) in first-line BRAF V600-mutant pLGG and single arm D+T in relapsed/refractory (r/r) BRAF V600-mutant pHGG has already been described. Briefly, the primary endpoint was the independently assessed overall response rate, ORR (CR+PR) using RANO criteria. The ORR was 47% (95% CI, 35%-59%) with D+T vs 11% (95% CI, 3%-25%) with C+V (P<.001; odds ratio, 7.2 [95% CI, 2.3-22.4]) in pLGG and 56.1% (95% CI, 39.7%-71.5%) in pHGG. Safety was consistent with the established profile of D+T in other indications. We report results for the Japanese subgroup. RESULTS A total of 6 Japanese pts were included in pLGG (D+T; n=4, C+V; n=2). And a total of 11 Japanese pts with diverse WHO Grade III/IV gliomas were included in r/r pHGG. The best overall response assessed by independent reviewer were as followed; D+T; SD 75% (n=3), PD 25% (n=1), C+V; CR 50% (n=1), PD 50% (n=1) in pLGG and CR 9.1% (n=1), PR 27.3% (n=3), SD 9.1% (n=1), PD 36.4% (n=4) in r/r pHGG. Treatment-related grade ≧3 adverse events were D+T; 25% (n=1) and C+V; 100% (n=2) in pLGG and 27.3% (n=3) in r/r pHGG. DISCUSSION AND CONCLUSIONS Treatment with D+T showed encouraging efficacy in Japanese pLGG and r/r pHGG. Profile of AEs was similar or consistent which is reported in other adult cohorts. Thus, these results suggest that D+T may represent a critical treatment advance for pLGG and r/r pHGG Japanese pts with BRAF V600-mutant.