Dr. Markowski on the Evaluation of Sabizabulin in mCRPC

Mark C. Markowski, MD, PhD, an assistant professor of Oncology at Johns Hopkins Medicine, discusses the evaluation of sabizabulin (VERU-111) in a phase 1b/2 trial (NCT03752099) in metastatic castration-resistant prostate cancer (mCRPC). 

The phase 1b/2 trial was conducted to determine a maximum tolerated dose and evaluate for preliminary efficacy in men with mCRPC resistant to androgen receptor (AR)–targeting agents.

A dose-escalation design comprised the phase 1 portion of the trial, and it enrolled patients who had previously received 1 prior AR therapy and up to 1 prior therapy with a taxane, Markowski says. Intrapatient dose escalation was permitted, and patients started with a low dose of sabizabulin administered once per day on a 1 week on, 2 weeks off schedule, Markowski explains. Patients who tolerated that dosing schedule moved to a 2 weeks on, 1 week off schedule, and patients who continued to do well moved to daily dosing, Markowski adds.

Investigators established 63 mg of sabizabulin per day, given continuously, as the recommended phase 2 dose. Though a maximum tolerated dose was not reached, the preliminary efficacy observed at the 63 mg dose prompted investigators to move to phase 2 at that level, Markowski continuous. The phase 2 study evaluated a similar patient population as phase 1, though prior chemotherapy was not permitted, and this portion of the trial evaluated prostate-specific antigen response rates and progression-free survival, Markowski concludes.