Scynexis’ new antifungal heads to phase 3 for yeast infections

A novel antifungal developed by Scynexis for the yeast infection vulvovaginal candidiasis (VVC) has bested the current standard therapy in a midstage trial and is moving to a phase 3 program.

Scynexis’ CEO Marco Taglietti, M.D., told investors on a conference call that SCY-078 could become a new treatment for the “many VVC patients not currently well served with oral fluconazole” which is currently the drug of choice in most cases.

SCY-078 is a member of the glucan synthase inhibitor class but has a novel triterpenoid structure that Scynexis says means it combines high antifungal activity with the potential to be delivered both intravenously and orally.

Current glucan synthase inhibitors include azole antifungals like fluconazole, as well as newer drugs like Merck’s Cancidas and Astellas Mycamine which have to be delivered intravenously and so are typically reserved for more serious fungal infections.

The efficacy of fluconazole as a VVC treatment can be as low as 55%, and there are currently no approved drugs for recurrent VVC, says Scynexis. In its phase 2b DOVE trial, a twice-daily oral dose of SCY-078 achieved a clinical cure in 14 of 27 patients (52%) after 10 days, compared to 14 of 24 (58%) with fluconazole. And by day 25, the cure rate for Scynexis was 70%, compared to 50% with the comparator drug.

There was also a significant improvement for Scynexis’ drug when it came down to antifungal rescue therapy, which was required in seven fluconazole patients but just one receiving SCY-078.

The biotech is taking the lowest 600-mg dose tested into the phase 3 program, as this provided the best profile in terms of antifungal activity and side effects—with tolerability “substantially improved” in this trial compared to Scynexis’ earlier phase 2a study reported in 2016, Taglietti added.

"We look forward to having our end-of-phase 2 meeting with the FDA and starting our phase 3 registration program for VVC, in which we anticipate oral SCY-078 will be evaluated for superiority versus placebo,” said Taglietti. If those trials are successful, its regulatory review should be swift, as the drug has both qualified infectious disease product (QIDP) and fast track designations from the FDA.

Scynexis is also recruiting patients into two trials looking at the drug’s activity in invasive candidiasis infection (CURES and FURI) with data readouts due before the end of the year, while a study in invasive aspergillosis will get underway this quarter.

Meantime, a new liposomal formulation of the drug for intravenous delivery is in late preclinical development with a first trial due in the coming weeks, and a phase 2b study in invasive candidiasis also scheduled to start in 2018.

Last year, Scynexis was hit hard after three healthy volunteers in a phase 1 trial of its earlier IV formulation of SCY-078 developed blood clots. The drug was originally developed by Merck & Co, which called it MK-3118.