CTNI-32. PHASE 2 STUDY OF VAL-083 AND RADIOTHERAPY IN NEWLY DIAGNOSED MGMT-UNMETHYLATED GBM

Abstract

Abstract VAL-083 is a novel bi-functional DNA targeting agent that induces inter-strand DNA cross-links at N7-guanine, leading to DNA double-strand breaks and cell death. In vitro and in vivo studies have demonstrated VAL-083 circumvents MGMT-mediated chemoresistance and differentiates it from other therapies used in the treatment of GBM, including temozolomide (TMZ). VAL-083 also acts as a radiosensitizer against GBM cancer stem cells in vitro. A Phase 2 study was conducted to evaluate the safety and tolerability of VAL-083 when administered concurrently with radiation therapy (RT) in newly diagnosed MGMT unmethylated GBM. Stage 1 was a dose-escalation phase to confirm the dose of VAL-083 in this setting. Patients received VAL-083 at 20, 30, or 40 mg/m2/day x 3 days every 21 days in combination with standard radiation treatment (RT) (2 Gy/day, 5 days/week for 6 weeks). Stage 2 was an expansion phase to enroll up to 20 additional patients at the 30 mg/m2/day of VAL-083 with RT. A total of 29 patients were enrolled in the study and completed treatment, with 25 patients receiving 30 mg/m2/day VAL-083. The median number of cycles completed by all patients was 9 (range 2-13). Consistent with our prior experience, myelosuppression was the most common adverse event. Pharmacokinetics (Cmax and AUC) of VAL-083 were broadly linear with respect to dose, and drug half-life was 0.8 hrs. In a sub-group of patients, levels of VAL-083 in CSF were found to be at least as high as those in plasma. The median progression free survival (PFS) for all patients enrolled was 9.3 (95%CI: 6.4-12.0) months. Eighteen (18/29; 62.1%) patients have died, and median overall survival for all patients enrolled was 19.6 (95%CI: 14.0-22.4) months. These results support the potential benefit of VAL-083 as a treatment alternative against GBM tumors with MGMT-mediated resistance to TMZ. Clinicaltrials.gov: NCT03050736.