What happened

Shares of the clinical-stage gene therapy company Voyager Therapeutics (VYGR 1.79%) dropped by as much as 11% in pre-market trading Tuesday morning. The biotech's shares are responding negatively to a regulatory delay for its Huntington's disease candidate, VY-HTT01.

After market close yesterday, Voyager announced that the Food and Drug Administration placed a clinical hold on the experimental gene therapy pending the resolution of certain chemistry, manufacturing, and controls (CMC) matters. The company said it expects to receive further details about the hold from the FDA within 30 days.  

Close up image of a double helix.

Image source: Getty Images.

So what

Huntington's disease is a genetic neurological condition that results in the death of cells within the brain. At present, there are an estimated 30,000 to 40,000 individuals within the U.S. who have this deadly neurological disorder, according to the peer-reviewed research. Moreover, there are no FDA approved drugs or therapies that treat the underlying cause of the disease.

Voyager is thus targeting a rather sizable commercial opportunity with VY-HTT01. This gene therapy will more than likely be a blockbuster product -- with sales of over $1 billion per year -- if it gains market access. Viewed in this light, it's easy to understand why investors aren't too happy about this clinical hold. 

Now what

A clinical hold for CMC matters isn't the end of the world. Far from it. The long and short of it is that VY-HTT01's clinical program should get back on track in the not-so-distant future, perhaps before the end of the year.