Abstract CT201: Phase 2 clinical trial of OKN-007 in recurrent malignant glioma

Abstract Background: OKN-007 is a novel nitrone anti-cancer agent. OKN-007 plus Temozolomide (TMZ) increased survival in glioma-bearing mice compared to TMZ alone. Furthermore, OKN-007 increased TMZ sensitivity in both TMZ-sensitive and TMZ-resistant cell lines. Following a phase I study in recurrent glioblastoma (rGBM), we initiated a phase 2 clinical trial (NCT04388475) of OKN-007 combined with TMZ to examine the efficacy, safety, and pharmacokinetic properties of OKN-007 combined with TMZ. Here, we report the safety and efficacy findings of this ongoing trial. Methods: This is a multi-center, open label phase 2 clinical trial in first or second rGBM WHO Grade (Gr) IV. Adult patients with rGBM previously treated with standard radiation and chemotherapy (Stupp regimen) were eligible. Any second-line therapy was acceptable, excluding bevacizumab. Patients were treated with OKN-007, administered intravenously, at 60 mg/kg, three times weekly for 12 weeks, then twice weekly for 12 weeks, then once weekly until progression. TMZ was administered orally, at a dose of 150 mg/m2 (Cycle 1) or 200 mg/m2 (subsequent cycles). An initial 3-patient safety lead-In cohort established the safety of the OKN-007 and TMZ combination in this patient population. Kaplan-Meier analysis was used to determine progression-free (PFS) and overall survival (OS). Additionally, a comparative analysis of PFS and OS for a matched external control rGBM population treated with lomustine in other formal randomized clinical trials was performed. Results: 57 patients were enrolled at study completion. Of 57 patients enrolled, there were no adverse events (AEs) deemed as a dose-limiting toxicity in the safety Lead-In cohort with 3 patients. Median age was 56 years (range, 29-82), and 41 patients were treated with one line of prior anti-cancer therapy and 15 were treated with two prior lines. Eighteen patients experienced 46 SAEs and of these 9 (Gr3 nausea, Gr2 vomiting, Gr3 fatigue, Gr2 infusion related reaction, Gr3 acute liver injury, Gr3 generalized weakening upper and lower extremities, Gr3 bilirubin increase, Gr3 AST and ALT increase) were deemed to be possibly related to administration of OKN-007. For 56 patients receiving the combination of OKN-007 and TMZ, median PFS was 2.2 (95% CI, 1.6-3.6) months vs. 1.8 (95% CI, 1.7-1.9) months in control patients. Median OS was 9.7 (95% CI 7.6-12.5) months vs. 7.2 (95% CI, 6.8-7.8) months (Cox hazard ratio (HR) = 0.68, p = 0.034). 6-month PFS rate was 23.6% (95% CI, 13.5-35.4) vs. 13.0% (95% CI, 10.0-16.4) and 12-month OS rate was 38.1% (95% CI, 25.1-50.9) vs. 26.3% (95% CI, 22.0-30.8), respectively. Conclusions: Our data indicate that the combination therapy of OKN-007 and TMZ appears safe and, compared to standard lomustine therapy, may prolong OS in rGBM. Citation Format: James Battiste, Glenn Lesser, Santosh Kesari, Varun Monga, Tobias Walbert, Kaylyn Sinicrope, Burt Nabors, Jason Schroeder, Eric Wong, Barry D. Anderson, Hyun Sook Kim, Shinwook Kang. Phase 2 clinical trial of OKN-007 in recurrent malignant glioma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT201.