- Repros Therapeutics is considering shifting focus to the vaginally delivered form of its drug Proellex (telapristone acetate), now that regulators have decided to keep in place a partial clinical hold on the oral version.
- In order for the Food and Drug Administration to potentially lift the hold, Repros will have to provide the agency with a large database of safety information, according to a Monday statement from the company.
- Safety concerns for oral Proellex, which is under investigation as a treatment for uterine fibroids and endometriosis, initially arose nearly a decade ago after some patients receiving the drug demonstrated elevated levels of liver enzymes.
The news is the latest setback in what seems like an endless clinical hold on oral Proellex. U.S. regulators issued a full clinical hold on the drug back in August 2009. Less than a year later, the FDA downgraded the hold to partial, and a low-dose escalating study completed in 2011 came out clear of liver toxicity issues, "suggesting these lower doses avoid the type of adverse events seen at much higher doses in earlier studies," according to Repros in their most recent 10-Q.
Yet, the drugmaker hasn't been able to shake off the partial hold status. In April, the company revealed that the FDA was not lifting the hold, as the agency was in the process of consulting internal agency liver experts about Proellex's safety. While the agency said it would accept more safety information from Repros to help in the decision making process, it appears there's a ways to go in convincing the regulators.
With that in mind, Repros may turn its time and money toward the vaginally administered form of Proellex, which is not under any clinical hold.
"We are encouraged by our clinical studies with our vaginal drug delivery program, which may provide the potential opportunity to differentiate our treatment from other orally-dosed compounds in development or on the market to treat uterine fibroids," Repros' CEO said in a July 17 statement.
"Clinical work done to date suggests that vaginal delivery of telapristone acetate has the potential to yield good efficacy with significantly lower systemic blood levels," he added. "Furthermore, we intend to leverage drug delivery technology that could offer dosing less frequently than once per day."
Investors, however, didn't respond well to the possible pivot. Repros shares plummeted on the news — down more than 45% to 32 cents per share — in Monday morning trading.
Elsewhere in Repros' pipeline, the company is currently wading through a European Medicines Agency decision on its estrogen receptor antagonist enclomiphene for the secondary hypogonadism indication. The drugmaker said it plans to file responses to the EMA for that application in the third quarter.