Stock Watch: Competitive Wrinkles Mar KalVista, Vertex, Ironwood Trial Successes

When KalVista Pharmaceuticals, Inc. announced that its oral plasma kallikrein inhibitor, sebetralstat, met all the endpoints in the Phase III KONFIDENT study of 136 hereditary angioedema (HAE) patients, its stock price soared up by nearly 40% in the premarket. As soon as the market opened for normal trading however, it fell by over 15% to finish the day down by 8%, underperforming the NASDAQ Biotech Index (NBI) by 6%. 

There were a few wrinkles in the study announcement, but these were probably not enough to justify the stock sell-off. For example, the primary endpoint of the start of symptom relief was earlier with the lower dose than with twice that dose although both were significantly quicker than placebo. In the secondary endpoint of time to resolve attack severity from baseline, there appeared to be little difference between the two doses, although again, both were significantly better than placebo. There was also the possibility of some over-billing in the announcement as KalVista’s CEO described sebetralstat as “the first oral on-demand therapy for the treatment of HAE.” BioCryst Pharmaceuticals, Inc