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Here's Why AnaptysBio Inc Rose as Much as 18.5% Today

Maxx Chatsko, The Motley Fool

What happened

Shares of AnaptysBio (NASDAQ: ANAB) rose over 18% after the company announced positive top-line data from an ongoing phase 2a trial investigating the potential of its lead drug candidate to treat a severe form of asthma. The therapeutic antibody, etokimab, demonstrated promise in treating severe eosinophilic asthma, which is characterized by severe inflammation and restriction of air pathways in an individual's lungs. 

The day after receiving a single dose of etokimab, patients averaged an 8% increase in a measure of lung capacity called forced exhaled volume in one second (FEV1) compared to placebo. That advantage increased to an average improvement of 11% on day 64 of the ongoing trial. No serious adverse events were reported, hinting that the drug candidate is well tolerated.

As of 12:22 p.m. EDT, the stock had settled to a 8.4% gain.

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Image source: Getty Images.

So what

AnaptysBio has high hopes for etokimab, which reduces inflammation by blocking the function of interleukin-33. The molecule, produced by the immune system in response to an allergen, triggers the production of a dozen or so other immune cells that cause inflammation -- and that inflammation is generally referred to as allergies, whether caused by ingesting certain foods or inhaling dust mites or pollens. The idea is that blocking interleukin-33 (rather than mopping up all the other molecules triggered by it) should get to the root of the problem and stop inflammation before it can get started.

The drug candidate has had mixed results against various allergic conditions, although that's to be expected considering many inflammatory disease pathways aren't fully understood. For instance, AnaptysBio decided to stop investigating etokimab as a potential treatment for peanut allergies after clinical data disappointed. But it's full-steam ahead in a phase 2b trial against skin disorder eczema, which is currently enrolling 300 patients and should be completed in the second half of 2019. There's also the ongoing phase 2a trial in eosinophilic asthma -- the source of today's news -- and a soon-to-be started phase 2 trial in an inflammatory disorder of the nasal linings called adult chronic rhinosinusitis with nasal polyps.

Now what

AnaptysBio has a promising approach to treating inflammatory diseases, which includes etokimab and one other clinical-stage drug candidate. It also boasts development partnerships with Celgene (inflammation) and Tesaro (oncology).

That said, etokimab will continue to lead the pipeline, and the latest interim data from the phase 2a study in eosinophilic asthma have given investors something to cheer about following the decision to drop the peanut allergy indication. Next up, AnaptysBio will provide follow-up data from day 127 of the asthma trial (likely by the end of the year), and it expects to initiate a phase 2b trial for the indication sometime in 2019. Both events will be important checkpoints for long-term investors.

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Maxx Chatsko has no position in any of the stocks mentioned. The Motley Fool owns shares of and recommends Celgene. The Motley Fool recommends AnaptysBio. The Motley Fool has a disclosure policy.