What happened

Shares of Assembly Biosciences (NASDAQ:ASMB) crashed on Friday, plunging 69.4% as of the market close. The huge drop came after the company announced disappointing results Thursday evening from a phase 2 study evaluating vebicorvir (VBR) in treating patients with chronic hepatitis B virus (HBV) infection.

So what

Clinical failures for lead pipeline candidates always cause biotech stocks to plummet. Assembly Biosciences' crash today is just the latest example.

Businessman looking at red stock arrow plunging through floor.

Image source: Getty Images.

The company had hoped that patients who had been treated for at least 12 to 18 months with a combination therapy featuring VBR would have sustained virologic response (SVR) even after discontinuing therapy. That didn't happen, with 39 of 41 patients in the phase 2 study relapsing.

Assembly Biosciences CEO John McHutchison thinks the attempt was worthwhile, though. He stated, "While we are just beginning to analyze the data and this is not the outcome we were hoping for, we firmly believe it was the right experiment to conduct, and the learnings will inform the field and our ongoing development programs."

All isn't lost for Assembly Biosciences. The biotech has other pipeline candidates in clinical testing, and it hasn't thrown in the towel on VBR.

Now what

Assembly Biosciences confirmed that it still expects to begin a pivotal late-stage study of VBR in the first half of 2021, evaluating the drug for chronic suppressive therapy. This study will be conducted with BeiGene, which licensed the rights to VBR in China.

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