INNV-14. OUTCOMES OF PATIENTS WITH ISOCITRATE DEHYDROGENASE-MUTANT WHO GRADE 4 ASTROCYTOMA TREATED WITH TUMOR TREATING FIELDS (TTFIELDS) THERAPY: A REAL-WORLD ANALYSIS

Abstract BACKGROUND Tumor Treating Fields (TTFields) therapy is approved for the treatment of patients with newly diagnosed glioblastoma, based on the EF-14 study which demonstrated improvement in progression free survival and overall survival (OS). EF-14 included patients with the isocitrate dehydrogenase (IDH) mutation (IDHmut), which has since been reclassified as IDHmut WHO grade 4 astrocytoma (Astrocytoma IDHmut/G4) and confers a more favorable prognosis than IDH wild type. However, large real-world datasets are lacking. Here, we report real-world outcomes of patients with Astrocytoma IDHmut/G4 treated with TTFields in the US. METHODS Utilizing electronic health records from the xCures real-world data platform, patients with newly diagnosed Astrocytoma IDHmut/G4 receiving TTFields in the US from January 1 to December 31, 2019 were analyzed and IDH-mut status was confirmed. Survival was analyzed based on IDH-mut status and TTFields usage, with patients categorized into 2 usage groups (minimum 30 days treatment): high (≥50%) and low (<50%) usage. RESULTS Among 1285 patients with known IDH status, 82 had an IDH-mut and were included. The median (range) age of patients was 40.6 (21–75) years, with the majority being men (n=58/71%) and with methylguanine-methyltransferase-promoter methylation (n=48/59%). Median TTFields therapy duration and usage were 9.4 months and 76.8%, respectively. OS at 2 and 4 years was 66% (95% CI: 56–77%) and 44% (34–57%), respectively. Patients with high TTFields usage had increased OS compared to low usage (HR: 0.53 [0.28–1.02], P=0.057, n=80). Among 22 patients with a minimum 4 years of survival, 5 were still on therapy as of the data cutoff. CONCLUSIONS These findings demonstrate the utility of the xCures platform in systematically assessing outcomes for a rare glioma subtype in the real-world setting, and suggests that patients with Astrocytoma IDHmut/G4 may benefit from TTFields therapy. Additional patient follow-up and correlative data will be presented.