Shares in Scynexis went into a tailspin yesterday after a trial of lead antifungal drug SCY-078 was halted by order of the FDA on safety grounds.
The regulator ordered the suspension of the study after three healthy volunteers in a phase 1 trial of an intravenous formulation of SCY-078 developed blood clots, and asked the company not to start any further trials until a safety review has been completed.
Scynexis was quick to point out that two phase 2 trials of an oral formulation are still proceeding as planned, but the news gave investors the jitters and its shares lost around a quarter of their value in after-hours trading.
In a statement, the biotech said there had been "three mild-to-moderate thrombotic events in healthy volunteers receiving the IV formulation of SCY-078 at the highest doses and highest concentrations in a phase 1 study."
The possibility that the IV formulation is somehow contributing to the blood clots "cannot be ruled out," it continued, while pointing out the rates of thrombotic events due to intravenous catheters reported in the literature are comparable to those observed in its study.
Scynexis is hoping to meet with the FDA in the second quarter to discuss the prospects for SCY-078, a novel glucan synthase inhibitor that is being developed for serious, invasive fungal infections—85% of which are caused by Candida and Aspergillus species in the U.S. and Europe.
Rising levels of resistance to established antifungals such as azoles and echinocandins have made the development of new drugs hugely important, and Aventis spinout Scynexis was able to capitalize on that when it went public in 2014, largely on the back of prospects for SCY-078.
The company has made much of the fact that SCY-078 is the first IV and oral non-azole antifungal agent with activity against both invasive fungal species. It was originally developed by Merck & Co, which called it MK-3118.
Towards the end of 2016, the company presented data from its phase 1 trial of the IV formulation that had allowed it to select a dose and formulation to take forward in trials. Now, it will have to go back to the FDA to discuss its formulation and dosing plans.