What happened

Shares of clinical-stage metabolism specialist Viking Therapeutics (VKTX -2.44%) were up by 12.4%, on abnormally high volume, as of 3:12 p.m. ET Tuesday afternoon. The big gain came after the company announced positive top-line results for VK2809 in its mid-stage trial for biopsy-confirmed non-alcoholic steatohepatitis (NASH), an increasingly common cause of liver transplants in the United States. 

Highlights of the study include a whopping 52% average reduction in liver fat at the drug's highest dose, 85% of VK2809-treated patients achieving at least a 30% reduction in liver fat, and statistically significant decreases in several key biomarkers like LDL-C, triglycerides, and atherogenic lipoproteins. VK2809, in short, appears to have a real chance at becoming a best-in-class treatment for NASH. 

So what

As things stand now, there are no Food and Drug Administration (FDA)-approved treatments for NASH. Current valuation estimates for this untapped drug market range from $30 billion to $50 billion per year. Thus, VK2809 could easily exceed $1 billion a year in sales as an FDA-approved NASH treatment. That's a sizable commercial opportunity for a company with a market cap of less than $2.5 billion at the time of this writing.  

Now what

Is Viking's stock still a buy? The fact that its shares are solidly in the green on a tough day for biotech stocks in general says a lot about the optimism surrounding the company's clinical pipeline. Not only does Viking have a potential best-in-class NASH therapy under development, but it also has an intriguing early-stage weight loss candidate. Aggressive investors, in turn, may want to consider buying this biotech stock before its shares climb even higher.