QOL-26. A RANDOMIZED, DOUBLE-BLIND PHASE 3 STUDY OF VORASIDENIB VS PLACEBO IN PATIENTS WITH MUTANT <i>IDH1/2</i>DIFFUSE GLIOMA (INDIGO): ANALYSIS OF HEALTH-RELATED QUALITY OF LIFE, NEUROCOGNITION AND SEIZURES

Abstract INTRODUCTION The Phase 3 INDIGO study (NCT04164901) is a randomized, double-blind evaluation of vorasidenib, an oral, brain-penetrant inhibitor of mutant isocitrate dehydrogenase (mIDH) 1/2 enzymes, compared with placebo, in patients with grade 2 mIDH1/2 diffuse gliomas, whose only prior treatment was surgery. The primary endpoint, radiographic progression-free survival by blinded independent review committee, and the key secondary endpoint, time-to-next-intervention, were significantly improved with vorasidenib versus placebo. As these patients are young, with several years’ life expectancy, impact of treatments on health-related quality of life (HRQoL), cognition and symptomatic burden is of interest. METHODS HRQoL, assessed by Functional Assessment of Cancer Therapy-Brain (FACTBr) questionnaire, was a secondary endpoint. FACT-Br was collected at baseline, Cycles 2 and 3, then every 3 months. Scores were interpreted using an estimate of clinically meaningful deterioration change from baseline for each arm. Exploratory endpoints included neurocognitive function, assessed by a validated battery of cognitive performance instruments, and seizure frequency and severity, assessed using a subject diary. RESULTS 331 patients were randomized to vorasidenib (n = 168) or placebo (n = 163) (median age, 40.0 years; Karnofsky performance scale = 100, 53.5%; ongoing medical history of seizures, 54.1%). Median follow-up was 14.2 months. No clinically meaningful deterioration from baseline FACT-Br total score and subscales were observed at any timepoint through the median treatment duration (Cycle 13) in either arm. At baseline, active seizures (≥ 1 seizure in the previous 30 days) were reported in 20/168 (11.9%) vorasidenib patients and 20/163 (12.3%) placebo patients. On-treatment seizure frequencies and cognition outcomes will be presented by arm. CONCLUSION INDIGO is the first randomized Phase 3 study of targeted therapy in grade 2 mIDH1/2 diffuse glioma. HRQoL, as measured by FACT-Br, was maintained during treatment with vorasidenib. These data support the clinical benefit of vorasidenib in this patient population for whom chemotherapy and radiotherapy are being delayed.