Enrollment Continues in Study Evaluating ONCT-534 For Advanced Prostate Cancer

A study evaluating a prostate cancer drug is currently enrolling patients with advanced prostate cancer.

Patients continue to be enrolled in a study evaluating the dual-action androgen receptor inhibitor ONCT-534 for the treatment of patients with advanced prostate cancer who are relapsed or refractory to approved androgen receptor pathway inhibitors (ARPIs), according to a news release from clinical-stage biopharmaceutical company Oncternal Therapeutics, Inc.

The first two participating patients, comprising the first and second cohorts of the study, were treated with 40 mg and 80 mg of oral ONCT-534 daily, respectively, while the third and fourth patients, as the study’s third patient cohort, have been enrolled to receive a 160 mg daily oral dose of ONCT-534, according to the news release.

“The ONCT-534-101 investigators are enthusiastic about this study, and we are excited about the enrollment and progress through the initial dosing levels. Reaching the third cohort represents an important milestone for the program, as we believe we are nearing potentially therapeutic doses that may benefit prostate cancer patients who have progressed after treatment with approved ARPI such as (Xtandi), (Zytiga), (Erleada) and (Nubeqa),” said Dr. Salim Yazji, chief medical officer at Oncternal Therapeutics, Inc. in the news release.

Yazji went on to explain the science behind ONCT-534.

“We believe ONCT-534, with its novel mechanism of action involving both the ligand-binding domain and the N-terminal domain of the androgen receptor (AR), may address a significant unmet medical need for patients with advanced metastatic prostate cancer, especially those with splice variants of the AR, mutations in the ligand-binding domain of the AR, or AR amplification, common mechanisms of resistance that may develop to treatment with currently approved AR pathway inhibitors,” Yazji said in the news release.

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The Food and Drug Administration (FDA) designated ONCT-534 as a Fast Track development program for the treatment of patients with relapsed or refractory metastatic castration-resistant (mCRPC) resistant to approve ARPIs in October 2023, according to a prior release from the manufacturer.

Fast Track designation, as the FDA explains on its website, is intended to facilitate development and expedite the review of drugs “to treat serious conditions and fill and unmet medical need. The purpose is to get important new drugs to the patient earlier.”

“It looks like our drug is a very strong candidate for treating these patients who have relapsed from current treatment options. It may potentially have the possibility to extend the survival,” said Ramesh Narayanan, the deputy director of the Center for Cancer Research and the Muirhead Endowed Professor in the College of Medicine at the University of Tennessee Health Science Center and one of the researchers who developed ONCT-534, in an article posted to the University of Tennessee Health Science Center’s website.

The current phase 1/2 ONCT-534-101 study is designed to evaluate the drug’s safety, tolerability and preliminary antitumor activity in its first phase, followed by further evaluation of its safety and antitumor activity with the goal of determining an optimum dose of the treatment, according to the latest announcement from Oncternal Therapeutics, Inc.

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There will be approximately 27 patients enrolled in the first phase of the study, and two cohorts of 16 patients each enrolled in the study’s second phase, according to its listing on clinicaltrials.gov. The study, which started in September 2023, is estimated to be completed in January 2028, according to the listing.

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