• A small North Carolina-based biotech got a lot smaller Tuesday, despite the company announcing its rare disease drug met the primary goal of a pivotal Phase 3 study.
• The critical hang-up for investors was the efficacy of BioCryst’s BCX7353, an experimental treatment for hereditary angioedema, a rare genetic disease. While the drug significantly outperformed placebo, the reductions in attack rates fell well short of similar results from competing drugs as well as prior Phase 2 data of the drug.
• BioCryst’s stock opened at $3.64, down 51% from Monday’s close. The company said it expects to file for regulatory approval in the U.S. by year’s end and in Europe in early 2020.

Hereditary angioedema, or HAE, causes a protein malfunction that can trigger potentially fatal attacks via swelling in different parts of the body. Several medicines have already been approved to treat the disease, either to prevent the attacks or to less their effect.

While BioCryst may have met its goal in its trial, the reaction from investors and analysts made clear the final results disappointed.

The Phase 3 trial randomized 121 patients between placebo and two dose levels of BCX7353, 110 mg and 150 mg. After 24 weeks of treatment, the low and high doses respectively showed 30% and 44% reductions compared to placebo in reducing attack rates.

The key competitor for BCX7353 is Takeda’s Takhzyro (lanadelumab). Its U.S. approval last August was based on late-stage data showing Takhzyro reduced HAE attacks by 73% as a monthly injection and by 87% when injected every other week. 

BioCryst has framed its drug, which is taken orally, as more convenient. That advantage could make up for modestly lower efficacy results, biotech analysts had said before Tuesday’s readout, but the results now spur questions of whether BioCryst’s drug delivered enough to compete. 

In a note to clients, RBC Capital Markets analyst Brian Abrahams called Tuesday’s results disappointing and below Wall Street’s hopes.

In Abrahams’ view, the data could still lead to an approval but might limit the drug to a niche role as a lower-cost therapy for HAE patients unwilling to try injectable treatment.

BioCryst executives said on a call with analysts they plan to heavily promote the drug for frontline use.

“We’re not going to battle it out with whose drug is better,” said CEO Jon Stonehouse. “We’re going to move the drug to the front of the line and we’re going to get people to try it, and many people are going to have a really good response.”

The company plans to offer a free sample period for patients to try the drug, and sees an opening in the market for a cheaper treatment option before other, more expensive, therapies. 

“These drugs are approaching $600,000 per patient per year,” Stonehouse said. “The flexibility we have here is enormous, and we will take full advantage of that to move our drug into frontline therapy.”

While 121 patients enrolled in the study, only 108 completed it. Five patients discontinued due to treatment-emergent adverse events, four of which were taking BCX7353, according to a company presentation.

It is unclear what happened to the other eight patients who did not complete the study. BioCryst did not respond to multiple requests for comment by time of publication.