CTIM-16. SAFETY AND PRELIMINARY EFFICACY OF AZD1390 + RADIATION THERAPY FOR GLIOBLASTOMA

Abstract BACKGROUND Glioblastoma is an aggressive cancer; intensity-modulated radiation therapy (IMRT) with concomitant and adjuvant temozolomide is the first-line standard of care. AZD1390, an ataxia telangiectasia mutated kinase inhibitor, aims to augment the efficacy of IMRT without exacerbating neurotoxicity. AZD1390 is optimized for blood–brain barrier penetration, confirmed in healthy volunteers (NCT03215381) and patients with glioblastoma (Phase 0; NCT05182905). This Phase 1, open-label study (NCT03423628) evaluated safety and efficacy of AZD1390 and IMRT in patients with glioblastoma. METHODS Adult patients received escalating once-daily AZD1390 doses with IMRT 35 Gy in 10 fractions over 2 weeks (Arm A, recurrent glioblastoma) or IMRT 60 Gy in 30 fractions over 6 weeks (Arm C, newly-diagnosed O-6-methylguanine-DNA methyltransferase unmethylated glioblastoma). Patients received 2 additional weeks of adjuvant AZD1390 post-IMRT. Primary objective was safety; secondary objectives included efficacy and pharmacokinetics. RESULTS As of Feb 6, 2024, 115 patients (Arm A=75; Arm C=40) received AZD1390 10–900 mg/day. Pharmacokinetics were linear, with a slightly more-than dose-proportional increase and mean elimination half-life ~9–11 hours. Most patients had ≥1 treatment-emergent adverse event (AE), most commonly fatigue (51.3%), nausea (39.1%) and headache (38.3%). Grade ≥3 AZD1390-related AEs occurred in 18/115 patients. The maximum tolerated dose was 400 mg (Arm A) and 300 mg (Arm C). Dose-limiting toxicities included creatinine kinase elevation (Arm A) and radiation skin injury (Arm C). AEs led to AZD1390 discontinuation in 15/115 patients. Safety profiles were mostly consistent across Arms despite different radiation schedules. At target-engaging doses, median overall survival was 12.7 months (95% CI: 10.7–18.9; Arm A) and still maturing (Arm C). CONCLUSIONS Concurrent AZD1390 and IMRT demonstrated manageable safety at doses with known target engagement. Preliminary efficacy is encouraging (Arm A). AZD1390 can potentially act as a radiosensitizer for glioblastoma treatment. Clinical investigation is ongoing.