What happened

Shares of Biohaven Pharmaceutical Holding Co Ltd (NYSE:BHVN), a clinical-stage biotech developing an experimental migraine treatment, are getting hammered after the company announced a pivotal trial that failed to impress. The stock was down 29.2% as of 11:28 a.m. EDT Monday.

So what 

Biohaven's lead candidate hit the marks that pivotal study protocols set before it, but the results suggest marketing rimegepant could be an uphill battle. In terms of post-dose pain freedom and freedom from most bothersome symptoms, patients taking the oral CGRP inhibitor reported significant improvements versus a placebo. Unfortunately for Biohaven, the improvements don't appear competitive with pivotal trial results Eli Lilly (NYSE:LLY) released for its acute migraine pain reliever, lasmiditan last summer. 

Person hiding their head under their laptop.

Image source: Getty Images.

It's important to note, these two drugs haven't been studied in a head-to-head trial, so any comparisons need to be taken with a grain of salt. In two identical studies, 19.2% and 19.6% of patients taking rimegepant reported pain freedom two hours after dosing, versus 14.2% and 12% in the corresponding placebo groups. When asked about most bothersome symptoms, 36.6% and 37.6% of patients in the rimegepant group reported relief versus 27.7% and 25.2% among those given a placebo.

Now what

Rimegepant's results are statistically significant, but they look a bit weak compared to lasmiditan's pivotal trial performance. A 200 mg dose of Lilly's candidate led 38.8% of patients to report freedom from pain at two hours, versus 21.3% in the placebo group. The same dose also helped 48.7% of patients report freedom from their most bothersome symptom at two hours, against 33.5% among those given a placebo.

If Biohaven's candidate eventually earns an approval, it could have more than Lilly's lasmiditan to contend with. In February, Allergan (NYSE:AGN) released data for an acute migraine candidate, called ubrogepant, that produced pivotal trial results that were comparable to, and perhaps better than, rimegepant's. 

If rimegepant fizzles, Biohaven doesn't have anything too thrilling in late-stage development to lean on. The company began dosing patients in a mid-stage trial with an obsessive-compulsive disorder candidate late last year, and the company is waiting for word from the FDA that could allow Biohaven to continue developing trigriluzole to treat ataxia. 

Cory Renauer has no position in any of the stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. The Motley Fool has a disclosure policy.