CTNI-53. A GLOBAL, RANDOMIZED, DOUBLE-BLINDED, PHASE 3 STUDY OF VORASIDENIB VERSUS PLACEBO IN PATIENTS WITH ADULT-TYPE DIFFUSE GLIOMA WITH AN IDH1/2 MUTATION (INDIGO): UPDATED EFFICACY RESULTS

The Phase 3 INDIGO study (NCT04164901) evaluated vorasidenib, an oral, brain-penetrant, dual inhibitor of mutated isocitrate dehydrogenase 1/2 (mIDH1/2), in patients with mIDH1/2 diffuse glioma. The primary endpoint of progression-free survival (PFS) per blinded independent review committee (BIRC), and key secondary endpoint of time to next intervention (TTNI), were met in the positive, preplanned second interim analysis (IA2). The study was unblinded in March 2023 following independent data monitoring committee recommendation. Here, we present results after an additional 6 months of follow-up between the database lock for IA2 (September 6, 2022) and study unblinding (March 7, 2023).

Patients with residual/recurrent grade 2 mIDH1/2 oligodendroglioma or astrocytoma were enrolled (≥12 years; Karnofsky Performance Status ≥80; measurable non-enhancing disease; surgery as only prior treatment; no immediate need of chemoradiotherapy). Patients were randomized 1:1 to vorasidenib 40 mg or placebo daily in 28-day cycles.

Overall, 331 patients were randomized (median age: 40.0 years; oligodendroglioma: 172; astrocytoma: 159). As of March 7, 2023, 123/168 (73%) patients remained on vorasidenib and 72/163 (44%) remained on placebo. PFS per BIRC remained in favor of vorasidenib (HR, 0.35; 95% CI, 0.25–0.49), and was consistent with PFS per investigator assessment (HR, 0.34; 95% CI, 0.23–0.50). Median PFS per BIRC: vorasidenib, not estimable (NE; 95% CI, 22.1–NE); placebo, 11.4 months (95% CI, 11.1–13.9). TTNI also remained in favor of vorasidenib (HR, 0.25; 95% CI, 0.16–0.40). Median TTNI: vorasidenib, NE (95% CI, NE–NE); placebo, 20.1 months (95% CI, 17.5–27.1). No new safety signals emerged.

Vorasidenib is a targeted therapy for patients with predominantly non-enhancing mIDH1/2 diffuse glioma following surgical intervention, as shown in the INDIGO population. These additional 6 months of follow-up confirm the previously reported statistically significant and clinically meaningful improvements in PFS and TTNI with vorasidenib.