CTNI-47. DOSE ESCALATION OF ASTX727 IN ADULT PATIENTS WITH RECURRENT/PROGRESSIVE NON-ENHANCING IDH MUTANT GLIOMAS

Abstract

Abstract BACKGROUND IDH mutant gliomas typically display a hypermethylation pattern known as the glioma CpG island methylator phenotype (G-CIMP) which results in gene activation that promotes gliomagenesis. This study aims to reverse this methylation signature and disrupt tumor growth via treatment with an oral demethylating agent. METHODS This is 2-stage clinical trial investigating oral ASTX727 (decitabine + cedazuridine, a cytidine deaminase inhibitor, as a combination tablet) in patients with recurrent primarily non-enhancing IDH mutant gliomas. The Dose Escalation Stage consisted of a single arm 3 + 3 design. The primary objective was to establish the MTD and assess safety in this patient population. RESULTS Eleven pts (F = 45%, M = 55%) with a median age of 44 yrs (range 26-61 yrs) were enrolled. Two DLTs (grade 4 neutropenia for >72 hrs) were observed in 5 pts enrolled at the starting dose (35 mg decitabine/ 100 mg cedazuridine for 5 consecutive days). Six additional patients were enrolled at dose level -1 (35 mg decitabine/100 mg cedazuridine for 4 consecutive days). There were no DLTs at dose level -1 and this was declared the MTD. Grade ≥ 3 AEs included neutropenia (5 pts), leukopenia (1 pt), lymphopenia (1 pt), hyponatremia (1 pt) and increased ALT (1 pt). Best treatment response was SD in 11 patients. At the time of last follow-up (5/15/23) 10 pts have discontinued treatment (8 for PD, and 2 based on physician decision), 2 pts (18%) have died due to disease progression, 8 pts remain alive and in follow-up, and 1 patient remains on treatment. Median duration on treatment was 212 days (range 36 days – not reached). CONCLUSIONS ASTX727 was well tolerated in patients with recurrent non-enhancing IDH mutant glioma at dose level -1 with no DLTs . A surgical expansion cohort is currently enrolling to confirm drug target engagement and explore pharmacodynamics.