wiegveld schreef op 8 april 2019 20:14:
To win in the Phase 3, BCX7353 must beat a placebo, but how the drug compares to currently approved HAE medicines is also really important.
As mentioned above, HAE patients have treatment options available. Takhzyro, marketed by Takeda (formerly Shire) is the preventive HAE therapy that serves as the best comparable to BioCryst’s BCX7353. Both drugs work by suppressing the same misbehaving protein. Takhzyro is administered via an injection under the skin. It was approved last August and has launched very strongly.
In the pivotal clinical trial that supported Takhzyro’s approval,
an every-two-week injection schedule led to an 87% reduction in the rate of HAE attacks, relative to placebo. When Takhzyro was injected once monthly, the HAE attack rate fell by 73% relative to placebo.
No one expects BCX7353 to beat Takhzyro on efficacy. It doesn’t need to, given the added convenience of a once-daily pill. However, BCX7353 can’t be demonstrably worse, either. How close must it come?
Brian Abrahams, the biotech analyst at RBC (and a BioCryst bull) believes a BCX7353 HAE attack rate reduction in the 55% range or higher will be sufficient for the drug to grab meaningful market share and push BioCryst’s stock price higher. Abrahams views an HAE attack rate reduction greater than 65% as a home-run scenario.
Results that come in 50% or lower might still be sufficient for BioCryst to achieve the primary endpoint of the study, but the meaningfulness of the result will be debated and investors will be disappointed, he added.
One investor who follows BioCryst closely and is slightly more cautious believes the minimum efficacy threshold for real-world success is 60%. He believes a reduction in HAE attack rate in the 50% range will make it very difficult for BCX7353 to compete against Takhzyro.