Shares of AbbVie (ABBV - Get Report) and Coherus Biosciences (CHRS - Get Report) were moving in opposite directions Monday afternoon after the the U.S. Patent and Trademark Office's Patent Trial and Appeal Board (PTAB) denied Coherus's petition  to invalidate AbbVie's Humira patent.

AbbVie stock was up nearly 6% in afternoon trade as shares of Coherus tumbled about 17%.

The decision makes it unlikely that there will be U.S. biosimilars of Humira before 2023, and "neuters much of the bear argument on AbbVie shares," Jefferies analysts said in a note. 

The firm reiterated a "buy" rating and $90 price target on the stock, noting that AbbVie is its top pick in large cap pharma. 

Coherus nonetheless implied that it would now challenge the patent through the courts. 

"There are additional scientific and legal approaches available to address the various formulation intellectual property challenges, and all of the arguments raised in our  [inter partes review] petition remain available in a District Court proceeding," Coherus CEO Denny Lanfear said in a statement. "Coherus remains committed to launching our Humira biosimilar once approved."

Humira generated $4.06 billion of the company's total $6.39 billion in revenue in the most recent quarter. 

Coherus will hold a conference call about the ruling at 2:30 p.m. EST.