Onconova Therapeutics, Inc. (NASDAQ: ONTX), shares rose above 37% to 0.586 in the post-market session today after the news that it has earned the U.S. Food and Drug Administration (FDA) clearance for a Phase 1 analysis to continue with ON 123300, a proprietary, differentiated, first-in-class multi-kinase inhibitor, under the Company’s Investigational New Drug Application (IND).
The Phase 1 study will be performed in the United States and will test the efficacy, safety profile, and pharmacokinetics of orally administered ON 123300 as monotherapy at elevated doses beginning at or beyond 40 mg daily for 28 consecutive days. Patients with relapsed/refractory advanced cancer, including but not limited to HR+ HER2-metastatic breast cancer patients with clinical resistance to licensed second-generation CDK4/6 inhibitors, will be included in the study. Once the dose escalation step of the trial is finished and the recommended Phase 2 dose is identified, additional HR+ HER2- postmenopausal metastatic breast cancer patients immune to licensed second-generation CDK4/6 inhibitors will be enrolled. Additional patient cohorts, including but not limited to patients diagnosed with advanced colorectal cancer, and non-lymphoma, Hodgkin’s particularly mantle cell lymphoma, are under consideration.
The development of this U.S. The phase 1 experiment varies from the ongoing research performed in China with ON 123300 by HanX Biopharmaceuticals, Inc., a partner of the firm, which doses patients for 21 days every day. To date, four patients have been enrolled in the HanX study, the second dosing cohort has been opened, and it is expected that patients with advanced cancer will continue to be enrolled at two sites before the recommended Phase 2 dose is identified. Notably, of the three currently approved inhibitors of CDK4/6, two are approved for 21-day cycle dosing and one is approved for 28-day cycle dosing. All three are blockbuster treatments sold by well-known pharmaceutical firms for HR+ HER2-metastatic breast cancer, and all of these licensed therapies include concomitant therapy with an aromatase inhibitor.