What happened

Shares of Assembly Biosciences (NASDAQ:ASMB) gained over 41% today after the company announced an update on its hepatitis B virus (HBV) programs. 

The first update, from a phase 2a study evaluating the lead drug candidate ABI-H0731, suggests that the pipeline asset is effective in reducing DNA and RNA signatures of the virus. The second update, from a phase 1b study of a next-generation drug candidate named ABI-H2158, suggests that the asset can reduce the activity of the virus after just 14 days. 

As of 3:53 p.m. EDT, the stock had settled to a 38.2% gain.

A businessman looking at his laptop while riding a cartoon rocket.

Image source: Getty Images.

So what

The two lead candidates of Assembly Biosciences belong to a class of drugs called core inhibitors. The compounds are intended to disrupt HBV replication and the pool of cccDNA -- a type of DNA required for certain viruses to replicate -- that is often permanently lodged in an individual's cells.

The biopharma announced that individuals treated with ABI-H0731 and nucleos(t)ide analogs (Nrtl) achieved a deeper decline in HBV DNA and RNA than those treated with Nrtl alone. The combination also led to steeper declines in the biomarkers thought to indicate the amount of cccDNA present in an individual's cells. 

The update for ABI-H2158 only mentioned that researchers observed "potent antiviral activity" from the drug candidate.

Now what

Assembly Biosciences provided updates from the ongoing clinical trials because each has been accepted into a late-breaking session of the American Association for the Study of Liver Diseases annual meeting on Nov. 11. Management intends to hold a conference call the same day to provide the information to investors, too. A market cap of just $330 million suggests Wall Street isn't too optimistic about the biopharma, but that could change depending on the details of the planned update. Investors will have to wait to find out.