What happened

Shares of AnaptysBio Inc. (NASDAQ:ANAB), a clinical-stage biotech developing anti-inflammatory drugs, fell 10.2% during Thursday's session before ending the day 7.5% lower. A downgrade from RBC Capital Markets citing recently released peanut allergy results are the culprit.

So what 

Last month, AnaptysBio showed us that a dose of its lead candidate, ANB020, helped six of 13 adults with moderate to severe peanut allergy symptoms tolerate a 500 mg dose of peanut protein two weeks later. In February, Aimmune Therapeutics (NASDAQ:AIMT) presented pivotal trial results from AR101, which helped 67% of pediatric patients tolerate a 600 mg dose of peanut protein. We really can't make apples-to-apples comparisons without a head-to-head study, but it looks like ANB020 could have fierce competition down the road.

Downward sloping chart floating over a person's hand.

Image source: Getty Images.

RBC Capital threw more water on the results by questioning the company's definition of "moderate to severe allergy symptoms" when selecting patients for the study.

Now what

Given the size of the trial -- there were just three patients in the control group -- RBC was probably right to discourage investors from ascribing significant value to ANB020 as a peanut allergy prophylactic.

Fortunately for AnaptysBio, mid-stage eczema results released last October are far more impressive than its peanut performance. Among 12 patients treated with a single dose of ANB020, nine had achieved a 50% or greater symptom improvement at 15 days, and 10 hit the same mark at 57 days.

Last year, Dupixent from partners Sanofi and Regeneron became the first new eczema treatment for patients who can't control their condition with topical steroids. Given the huge unmet need for stronger eczema medicines, it's expected to generate more than $4 billion in annual sales at its peak. It's hard to make comparisons to ANB020 at the moment, but it looks like AnaptysBio's candidate could compete for a significant share of an enormous eczema market in the years ahead.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.