Abstract CT275: A phase 2, randomized, open-label study of onvansertib in combination with standard-of-care (SoC) versus SoC alone for first-line treatment of RAS-mutant metastatic colorectal cancer (mCRC)

Abstract Background: Chemotherapy in combination with bevacizumab (Bev) has been a standard first-line treatment for RAS-mutated mCRC patients for the last 2 decades. The prognosis of these patients remains poor. Onvansertib is an orally available, highly potent, and selective inhibitor of Polo-like kinase 1 (PLK1), currently in clinical development. In a Phase 1b/2 study, onvansertib in combination with FOLFIRI + Bev demonstrated safety and promising efficacy in the second-line treatment of KRAS-mutated mCRC patients (NCT03829410). A subgroup analysis showed that patients not exposed to Bev (Bev-naïve) in the first-line setting had superior clinical benefit compared to Bev-exposed patients. Based on this data, we propose to investigate the combination of onvansertib with SoC (chemo + Bev) in the first-line treatment of RAS-mutated, Bev-naïve mCRC patients. Methods: This exploratory Phase 2, open-label, randomized study is designed to assess the safety, efficacy, pharmacokinetics, and pharmacodynamics of 2 doses of onvansertib (20 mg and 30 mg) in combination with SoC (FOLFIRI + Bev or FOLFOX + Bev) versus SoC alone in patients with RAS-mutated metastatic and unresectable CRC in the first-line setting. Eligible participants must have histologically confirmed mCRC, KRAS or NRAS mutation, no previous systemic therapy in the metastatic setting, ECOG performance status of 0 or 1, measurable disease as defined per RECIST v1. 1. Exclusion criteria include patients with BRAF-V600 mutations or microsatellite instability high/deficient mismatch repair, prior treatment with a VEGF inhibitor, previous oxaliplatin treatment within 12 months prior to randomization. The primary endpoint is objective response as determined according to RECIST v1. 1 by an independent central review. Key secondary endpoints include progression-free survival and duration of response per independent central review. The study will enroll approximately 90 patients. Each patient will be randomized to be treated with onvansertib (20 mg or 30 mg) + SoC or SoC alone. The enrollment period for this study is approximately 12 months. Patients will be followed for overall survival for up to 1 year after the end of treatment. Trial is open and recruiting as of November 2023. This trial is registered as NCT06106308. Citation Format: Heinz-Josef Lenz, Benjamin Kuritzky, Anu Thummala, Stephan Kendall, Ravindranath Patel, Sreenivasa R. Chandana, Alisha H. Bent, Nancy Sherman, Ramanand Arun Subramanian, Fairooz Kabbinavar, Joel Randolph Hecht. A phase 2, randomized, open-label study of onvansertib in combination with standard-of-care (SoC) versus SoC alone for first-line treatment of RAS-mutant metastatic colorectal cancer (mCRC) 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 (7Suppl): Abstract nr CT275.