Gemphire stock sinks as ex-Pfizer LDL drug data disappoint

Gemphire Therapeutics has posted data on its oral inhibitor of cholesterol production. The phase 2b met its primary endpoint but also linked gemcabene to a smaller-than-hoped drop in LDL cholesterol, raising doubts about the commercial viability of the asset. 

Investigators enrolled 105 patients with elevated levels of LDL and randomized them to receive either gemcabene or placebo. Subjects continued to take statins and, in some cases, Merck’s Zetia. After 12 weeks, investigators assessed the change in each patient’s LDL-C from their baseline level.

The 17.2% decline in LDL-C in the gemcabene arm bettered the 5.5% seen in the placebo cohort. But the placebo-adjusted decline of 11.7% is lower than seen in previous studies. An earlier, 8-week phase 2 linked gemcabene to placebo-adjusted declines of greater than 20%, although the participants in that trial had higher starting levels of LDL-C.

Gemphire acknowledged the gap between data from the trials in its release of the top-line results. 

"The magnitude of LDL-C lowering was less than observed in certain prior studies of gemcabene," Gemphire CMO Lee Golden, M.D., said in a statement.

Investors responded to the results by driving down Gemphire’s shares by more than 40% before the market opened. That drop wiped out gains made by Gemphire in the run-up to the release of the data, which had driven its share price up well above the $10 secured for its IPO a year ago.

The IPO teed Gemphire up to take gemcabene through a clutch of phase 2 clinical trials. But it has experienced ups and downs since raising the money. CEO Mina Sooch walked away from the biotech in May. The next month, a phase 2b testing gemcabene in homozygous familial hypercholesterolemia met its primary endpoint, marking the start of a multiweek rise in Gemphire’s stock. The latest phase 2 data brought the rise to a crunching stop. 

Gemphire is now reviewing the data before deciding how to proceed. The Livonia, MI-based biotech is testing gemcabene in a few indications. And the clean safety profile seen in the phase 2 bodes well for gemcabene, provided it can also deliver impressive efficacy data.