Pfizer's immunology ambitions delayed—again—as JAK drugs fall victim to FDA's protracted safety review

Pfizer and its JAK inhibitors are falling deeper down a regulatory rabbit hole the company itself opened up. 

The FDA has once again pushed back two decisions key to Pfizer's immunology franchise: Xeljanz in ankylosing spondylitis and abrocitinib in atopic dermatitis, the New York pharma said Wednesday.

The latest delay came on top of an initial holdup Pfizer unveiled in April, when the FDA extended those reviews by three months. This time, Pfizer didn’t say whether the FDA had set new deadlines.

The problem stems from none other than Xeljanz itself. In an FDA-mandated safety study, the JAK inhibitor turned up increased risks of major cardiovascular problems and cancers when compared with a TNF inhibitor—either AbbVie’s Humira or Amgen’s Enbrel—in rheumatoid arthritis patients.

RELATED: AbbVie, Lilly atopic dermatitis hopefuls hit with more delays as FDA's JAK inhibitor holdups carry on

In explaining Xeljanz’s and abrocitinib’s extensions, the FDA pointed to its ongoing review of safety data from the Xeljanz postmarketing study, Pfizer said.

“We look forward to hearing from the FDA as we work to bring these important potential treatment options to the appropriate patients,” Michael Corbo, Ph.D., Pfizer’s chief development officer of inflammation & immunology, said in a statement. The company is still confident in both drugs' current risk-benefit profiles, he added.

But the FDA is taking a more cautious approach. As the regulators weigh what the safety data mean, with no sign of progress, fellow JAK inhibitors one after another have found their applications stalled at the agency—sometimes with major commercial consequences.

RELATED: AbbVie's big Rinvoq ambitions—and the larger JAK class—face even more uncertainty with latest FDA delays

Just a few days ago, AbbVie’s Rinvoq and Eli Lilly’s Olumiant, both looking to expand into atopic dermatitis, saw their FDA decisions pushed back for a second time. For Rinvoq, the additional delay followed similar hiccups in psoriatic arthritis and ankylosing spondylitis about a month ago.

As one of the drugs tasked with carrying the immunology torch after Humira loses U.S. exclusivity in 2023, Rinvoq comes with blockbuster expectations. For atopic dermatitis alone, AbbVie is projecting sales of $2 billion for Rinvoq by 2025.

In addition, Incyte’s Jakafi and its topical version, ruxolitinib cream, have also been dragged into the JAK safety swirl. The drugs’ potential uses in chronic graft-versus-host disease and atopic dermatitis, respectively, have been held up at the FDA with new FDA goal dates set for September.

Editor's note: The story has been updated to show that Jakafi and ruxolitinib cream have PDUFA dates in September.