Onconova Therapeutics has dosed the first patient in its Phase I/IIa clinical trial of narazaciclib combined with letrozole to treat endometrial cancer.

The multicentre, open-label study will evaluate narazaciclib in combination with letrozole as a second or third-line treatment for patients with recurrent metastatic low-grade endometrioid endometrial cancer (LGEEC).

The company intends to conduct the trial at the study’s principal investigator site, sites affiliated with MD Anderson Cancer Center, US Oncology Research sites, and NYU Langone Health.

The Phase I dose escalation portion of the trial will be initiated first followed by a Phase II expansion cohort.

Determining a recommended Phase II dose (RP2D) by evaluating the safety, tolerability, pharmacokinetics, and pharmacodynamics of the combination is the primary objective of the Phase I portion.

Phase II expansion cohort will enrol over 30 patients and its primary objective is to evaluate the efficacy of the combination at the RP2D, as measured by 24-week progression-free survival.

In addition, exploratory objective of the study is to record the estrogen/progesterone receptor status of participants.

Onconova president and CEO Steven Fruchtman said: “Our recurrent LGEEC programme provides an opportunity to establish narazaciclib as a best-in-class therapy in an indication where clinical proof-of-concept for its mechanism of action has been demonstrated.

“We, therefore, view the programme as a key avenue for value creation and look forward to our Phase I/IIa trial’s preliminary data readout expected later this year.”

A multi-kinase inhibitor, narazaciclib targets CDK 4, CDK 6, and other kinases which are important for cell proliferation and motility.