Why Hyperion Therapeutics Inc. Shares Popped

Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares of Hyperion Therapeutics , a biopharmaceutical company focused on treatment hepatology disorders and other orphan diseases, jumped as much as 15% after publishing the midstage results of its glycerol phenylbutyrate (GPB) study for the treatment of hepatic encephalopathy (HE) -- a worsening of brain function due to reduced liver function -- in the March 2014 issue of Hepatology.

So what: According to Hyperion's results, which tested 178 patients with liver cirrhosis, "GPB significantly reduced the proportion of patients who experienced a HE event (21% compared to 36%), as well as the time to first HE event." With a hazard ratio of 0.56, this would imply a 44% clinical risk reduction in first-time HE events for those taking GPB. Hyperion notes that since the trial met its primary endpoint it will be moving onto a pivotal phase 3 trial later this year or in early 2015.

Now what: There's no way to construe this as anything but good news for Hyperion. GPB demonstrated a meaningful reduction in HE events and length of time noted to first HE event for studied patients. Although Hyperion estimates that its drug could target some 140,000 cirrhosis patients in the U.S., investors should also understand that HE drug competition can be fierce, and Hyperion's GPB would be in no way guaranteed of gaining significant market share. Furthermore, with Hyperion now valued at six times the peak sales of its lone FDA-approved urea-cycle disorder drug Ravicti, I'd suggest that its shares could be nearing a high-water point.