Onconova Therapeutics Inc. (NASDAQ:ONTX) has filed an Investigational New Drug application with the FDA for ON 123300, its novel, first-in-class differentiated multi-kinase inhibitor. The company is seeking permission from the IND to commence Phase 1 ON 123300 trial in refractory/relapsed advanced cancer. Onconova is studying the inhibitor in patients with HR+ HER 2-metastatic breast cancer that are nonresponsive to current second-generation CDK4/6 inhibitors.
ON 123300, an advanced cancers alternative treatment
Steven Frutchman, the company’s CEO and President said that ON 123300 presents a proprietary approach for studying advanced cancers based on its action mechanism. He said that they are delighted to have filed the IND on time. They are looking forward to commencing enrolment in the US to complement the ongoing Phase 1 dose-escalation study in China by HanX Biopharmaceuticals.
Onconova’s partner HanX commenced the Phase 1 ON 123300 study in September 2020, it has enrolled three patients. The company expects to continue enrolling advanced refractory/relapsed cancer patients at two sites until they identify the recommended Phase 2 dose. Frutchman said that they are optimistic data from the two studies will deliver important data that will inform late-stage trials.
Evaluating safety and tolerability of ON 123300
Phase 1 ON 123300 study in the US will evaluate the inhibitor’s tolerability, safety, and pharmacokinetics as an oral monotherapy administered at increasing doses from 40 mg or higher daily for 28-day cycles. The company has planned the Phase 1 study for refractory and relapsed advanced cancer patients that include HR+ HER2- metastatic breast cancer patients with clinical resistance to CDK4/6 inhibitors. Once the company identifies the recommended Phase 2 dose, Onconova will enroll ore HR+ Her 2-postmenopausal metastatic breast cancer patients refractory to the current CDK4/6 inhibitors.
Interestingly, the US’s trial design is different from the ongoing HanX study in China, where patients are receiving doses for 21 days. Most importantly, out of the three currently approved second-generation CDK4/6 inhibitors, two have 21-day administering cycles while the other has a 28-day dosing cycle.