BioCryst gets a big boost from its latest HAE data, but it still faces a dangerous high wire act and giant rivals

Jon Stonehouse

A little more than a year ago, shares of Research Triangle Park, NC-based BioCryst $BCRX were crushed by a failed Phase II trial for their lead drug for hereditary angioedema, or HAE. Setbacks like that are not new for BioCryst. But the biotech turned to another HAE drug coming up the pipeline. And on Thursday, researchers detailed their second interim data review of the drug, and won a 31% spike for their stock with an overall positive take on the mid-stage data.

It’s just a snapshot — interim reviews of what is, after all, an interim study can be misleading, if not primarily aimed at boosting a stock — but the biotech did build some badly needed confidence for this latest attempt to develop an important new therapy.

The numbers did not reflect a dose dependent reduction in HAE attacks, which the biotech – somewhat controversially – has been explaining as a misread by trial participants. Researchers are insisting that the patients are recording “transient abdominal adverse events” as symptoms of an HAE attack in the two highest doses.

The details on now 44 patients from the APeX-1 trial:

In the intent-to-treat (ITT) population, corresponding reductions by treatment group were: 125 mg QD, 73% (p=0.004); 250 mg QD, 44% (p=0.090) and 350 mg QD, 45% (p=0.014) compared to placebo.

Obviously, BioCryst has a long way to go before it can pitch a drug like this to regulators. But its backers have been encouraged by the positive sets of data that they have been seeing. A final readout of the Phase II is expected in the third quarter.

Leerink’s Jason Gerberry has been tracking the drug, noting earlier in the year that BioCryst not only has to succeed in trials, it also needs to beat the competition, notably Shire’s Cinryze as well as its experimental late-stage drug SHP643. As an oral drug, BioCryst would have a leg up over injectables. But final safety and efficacy data will still need to be strong, relative to the competition.

After the first cut of the HAE data, Gerberry noted that BioCryst’s drug “compares to stat sig mean reductions (at 12-weeks) in ITT groups for the following competitive agents: 50% for Shire’s Cinryze, 88-100% for Shire’s SHP643 and 67-88% for CSL’s Haegarda.”

Shire’s pivotal data on SHP643 came through just days ago, and remains on the high side.

A 300 mg dose of the drug twice a month delivered an 87% reduction in mean HAE attack frequency, compared to 0% in the placebo group. It hit the primary endpoint with “highly” statistically significant results as well as all the secondaries.

Now Shire will dispatch an NDA to the FDA later this year, leaving little BioCryst to come up from behind with a lot to prove. Another failure for BioCryst would be dealt with harshly.

“These data support our hypothesis regarding the initial findings seen from the first interim analysis,” said Jon Stonehouse, chief executive officer and president of BioCryst. “We are delighted to see that a daily dose of 125 mg of BCX7353 results in a high level of efficacy with an improved tolerability profile compared to the 350 mg dose observed in the first interim analysis. We look forward to completing Part 3 of the trial to select appropriate doses for our pivotal program.”

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