With a phase 3 fail, Biohaven learned the hard way why AstraZeneca dropped a CNS drug in 2018

AstraZeneca wanted to rid itself of a protein inhibitor in 2018 after midstage studies, and now Biohaven Pharmaceuticals has found out why: The experimental treatment failed a phase 3 trial in people with multiple system atrophy (MSA).

To make matters worse, the drug failed secondary measures as well. More analyses are to come, and Biohaven will present full study results at an upcoming scientific meeting, the company said Monday. Investors seemed relatively unaffected by the news, with shares down 1% to $132 a piece as of 10:10 a.m. ET, though Biohaven has an approved drug in Nurtec for migraines, which always helps with pipeline flops.

Similar to investors, Mizuho analysts seemed relatively unfazed by the news. The analysts said expectations were “quite low” for the trial given “investor expectations were fairly guarded.” It “makes sense” to squash further efforts for the drug in MSA, the analysts said Monday. For now, Biohaven can rest easy given the uptake of oral Nurtec, which was given the FDA green light for acute migraine prevention in May.

RELATED: Biohaven picks up AstraZeneca CNS drug, plans phase 3 

The phase 3 trial of 336 patients failed slow disease progression compared to placebo over the course of nearly a year. The primary endpoint was based on a scale that measures functional disability, motor impairment, blood pressure, heart rate and chore-based disability. 

Biohaven licensed the treatment—myeloperoxidase (MPO) inhibitor verdiperstat (then known as AZD3241)—from AstraZeneca for $3 million upfront and about $4 million worth of shares. Another $55 million in regulatory and commercial biobucks and $50 million in sales-based milestones are on the line, according to Securities and Exchange Commission filings. These are pretty small numbers, and perhaps indicative of a small bet being made on a risky asset.

The Big Pharma had originally completed a 32-patient trial in 2016 but decided to cull the drug from further development in the treatment of MSA. The rare and progressive neurodegenerative disorder leads to loss of function and death of certain nerve cells in the brain and spinal cord. Biohaven rolled the dice to see whether it could have better luck, but they've come up with snake eyes.

RELATED: Biohaven flunks Alzheimer's phase 2/3, touts failed subgroup as sign of efficacy

There are no disease-modifying treatments for the debilitating disease that leads to death within a median six to 10 years post-symptom onset. MSA affects between 15,000 and 50,000 Americans, according to the National Institute of Neurological Disorders and Stroke.

Other companies attempting to crack the code for a disease-modifying treatment of MSA include German biotech Modag and South Korean biotech Peptron. Bayer's AskBio also joined the hunt when it acquired gene therapy programs from Brain Neuropathy Bio in January.

While Biohaven's drug failed to move the needle in MSA, the company believes verdiperstat still has a shot in amyotrophic lateral sclerosis (ALS). The biotech thinks targeting brain inflammation "remains strong in other disease states." The drug's trial in ALS is ongoing, and enrollment is slated to end next quarter.

Biohaven is no stranger to hurdles in clinical development. The biotech failed a phase 2/3 study of a different drug candidate in Alzheimer's disease in January.