EPID-10. CNSONTRK STUDY: CLINICAL CHARACTERISTICS AND OUTCOME OF CENTRAL NERVOUS SYSTEM TUMORS HARBORING NTRK GENE FUSIONS

Abstract

Abstract BACKGROUND TRK fusions are detected in less than 2% of central nervous system (CNS) tumors. There are limited data on the clinical course of affected patients. METHODS We conducted an international retrospective cohort study of patients with TRK fusion-driven CNS tumors. Data extracted included demographics, histopathology, TRK gene fusion, treatment modalities and outcomes. The growth modulation index (GMI) was calculated as a ratio of time to progression with TRK inhibitors to time to progression with the prior line of therapy. RESULTS 119 patients with TRK fusion-driven primary CNS tumors were identified. Median age at diagnosis was 4.5 years (range 0.0–78.3); 101 (85.6%) were < 18 and 45.3% were < 3 years of age. The most frequent tumor location was hemispheric (63.8%). Tumor types included 68 high-grade gliomas (HGG; 57.1%), 33 low-grade gliomas (LGG; 27.7%), 5 embryonal tumors (4.2%) and 13 others (10.9%). Median follow-up was 38.5 months (range 0.03–229.3). Pediatric patients had a better prognosis with a median OS of 185.5 months compared to 24.8 months in adults (p< .0001). Patients with LGG also had a better outcome with median OS that was not reached for LGG compared to 99.5 months for HGG and 38.5 months for embryonal tumors (p=0.0012). Out of 16 evaluable treatment regimens with larotrectinib an objective response was reported in 11 (11/16 (68.8%)-4 CR, 5 PR and 2 MR) compared to 38.1% for non-targeted treatment regimens (24/63 (38.1%)-10 CR, 13 PR and 1 MR). The GMI was 2.11 for pediatric patients treated with larotrectinib. CONCLUSIONS We report a large cohort of patients with TRK fusion-driven primary CNS tumors. Children with LGG glioma had a favorable outcome compared to adult and HGG. Larotrectinib appears to be associated with a better response rate and longer duration of response compared to non-targeted therapy.