Flex Pharma falls on cramp treatment update

Flex Pharma ($FLKS) saw its shares tumble by 17% premarket this morning on the news that its med had hit trouble in its latest study, although it did have some better news from its chat with the FDA.  

Its discussion with the regulator, which happened last month, saw the thinly traded micro-cap biotech have a pre-IND meeting over its FLX-787 candidate, a topically acting, selective transient receptor potential ion channel agonist in tests for nocturnal leg cramps (NLC), as well as multiple sclerosis, amyotrophic lateral sclerosis, and other disorders.

The company said in a statement today that at that pre-IND meeting, the FDA said that its preferred top target of cramp frequency “could be an acceptable primary efficacy endpoint” for its NLC test.

But the U.S. regulator also said the company should “utilize a parallel design in a planned IND-opening study due to the potential for confounding clinical results caused by carry-over effects, unblinding and other concerns with crossover studies.”

Flex said it was planning a parallel design Phase II in NLC for the first half of next year, after the IND application has been submitted and accepted.

It also posted an update for its exploratory NLC study of FLX-787 oral disintegrating tablet, of which the results were mixed.

In this randomized, blinded, controlled, crossover study, 72 subjects who suffer from nocturnal leg cramps at least four nights per week were enrolled at three clinical sites.

After an initial two-week placebo run-in period, subjects were randomized to either 17 mg ODT FLX-787 or ODT placebo for three weeks. Patients were then crossed over to the other treatment for an additional three weeks.

The biotech said that its “preliminary analysis” of the entire crossover data set “did not demonstrate a statistically significant difference versus placebo” when it came to its prespecified endpoints of muscle cramp frequency, or cramp-free nights.

But the company noted that it believed there were “a number of concerns” that could have messed with its data, or at least the interpretation of it at one of the sites, although these concerns were not made public.

It said if it took these data out, and that the analysis is restricted to patients from the two other sites made up of 37 patients, FLX-787 did manage to show “a strong trend on muscle cramp frequency” against placebo--although it says this comes “despite the limited data set not being adequately powered to show statistical significance.”

In a statement, the company said: “We continue to analyze the data between the sites to determine which of the issues, if any, may be meaningful. We believe that FLX-787 was well-tolerated, with no serious adverse events reported.”

“We believe that the data sets reported here, which include efficacy signals from two exploratory NLC human efficacy studies and a clear dose-response curve in our electrically-induced human cramp model, establish the positive effects of FLX-787 on human muscle cramping,” said Flex Pharma CMO Dr. Thomas Wessel in the statement. “Over the past year we have gained important insights from these exploratory studies regarding subject characteristics, clinical endpoints, dosing and formulation that will inform our human efficacy studies moving forward. We believe the magnitude of beneficial effect found in these studies, as well as in our previously reported efficacy study, bode well for our planned Phase II study.”

Last year the biotech, founded by serial biotech entrepreneur Christoph Westphal, pulled off a $86.4 million IPO--above its expected range. Investors were not happy first thing this morning however, with its shares falling premarket by 16.9% to $9.30 a share.