Shares of BioCryst Fall After Phase III HAE Drug Underwhelms Investors

Shares of North Carolina-based BioCryst Pharmaceuticals are down more than 53% this morning after the company released data from a Phase III trial that has underwhelmed analysts.

BioCryst said its Phase III APeX-2 trial for prevention of hereditary angioedema (HAE) attacks achieved its primary endpoint. That’s normally a signal for investors to buy the stock, but that wasn't the case Tuesday morning. Shares of BioCryst had fallen nearly $4 per share to $3.44 as of 9:53 a.m. The investor exit signals disappointment with the results.

BioCryst said its experimental treatment BCX7353, a selective inhibitor of plasma kallikrein, hit the mark in the late-stage trial, with the 150 mg dose reducing the attack rate in HAE patients by 44% compared to placebo. Additionally, the company said 50% of the patients who took the high dose had a 70% reduction in their HAE attack rate compared to baseline. Patients on the placebo side only saw a 15% reduction, the company said. Also, patients taking the 150 mg dose who had a baseline attack rate of fewer than two attacks per month, saw a reduction in HAE attack rate by 66% compared to placebo. For those patients who had an attack rate greater than two per month, the rate was reduced by 40%.

Those results though don’t stack up to Takeda’s Takhzyro (lanadelumab-flyo), which was approved last year by the U.S. Food and Drug Administration. Takhzyro is also an inhibitor of kallikrein, an enzyme which is chronically uncontrolled in people with HAE. In the Phase III data that led to approval, patients treated with Takhzyro experienced a “statistically significant reduction in mean HAE attack frequency of 87 percent compared to placebo.” In addition to Takhzyro, Takeda also has older treatments for HAE in its pipeline, including Cinryze and Firazyr. Takeda gained all three drugs from its $62 billion acquisition of Shire.

Despite the fact that BCX7353 doesn’t stack up to the Takeda drug, BioCryst Chief Executive Officer Jon Stonehouse put the best face on the results that he could. In a statement, Stonehouse said HAE patients “desperately want access to a cost-effective, convenient, oral therapy to manage their disease.” With the results demonstrated by the 150 mg dose of BCX7353, Stonehouse said his company has a new oral therapy that patients will want to try.

“With successful results from APeX-2, BioCryst is committed to making it easy for HAE patients around the world to access this potentially life-changing oral therapy, and we believe BCX7353 is positioned to become a front-line therapy option,” Stonehouse added.

BioCryst plans to submit a New Drug Application to the FDA in the fourth quarter of 2019 and a Marketing Authorization Application to the European Medicines Agency in the first quarter of 2020.

HAE is a rare, genetic disorder estimated to affect about one in 10,000 to one in 50,000 people worldwide. The condition results in recurrent, localized edema (swelling). The areas of the body most commonly affected are the extremities, gastrointestinal tract and upper airways. The swelling can be debilitating and painful, potentially impacting both work and education for people living with HAE. Swelling of the throat can be life-threatening due to asphyxiation.

BioCryst also pointed to the safety profile of the drug. No drug-related serious adverse events were reported during the trial. The company said that of the 108 patients who completed 24 weeks of study drug treatment, 100 percent continued into the ongoing 48-week extension phase of the trial.