R&D

Pfizer jumps into the heated PhIII race for new-wave JAK inhibitors — but safety frets loom large

Pfizer has racked up a positive slate of Phase III data for its anti-inflammatory JAK1 inhibitor abrocitinib (PF-04965842), which the pharma giant is hoping to steer to the FDA relatively soon as it looks to get into a heated blockbuster race that’s been heavily overshadowed by new safety warnings for the class.

All we’re getting now are some unspecified — though promising — results, with the pharma giant laying claim to a statistically significant result against a placebo for atopic dermatitis. Pfizer, though, wants to go up against some deeply entrenched rivals in a highly competitive field, and there’s no real insight to offer on how that stacks up. 

Abrocitinib is a JAK1 inhibitor, looking to bust into a market dominated by its own franchise drug Xeljanz, with Eli Lilly’s Olumiant angling in for a slice of the pie after the FDA approved on the low dose of the drug after initially rejecting it on safety fears. 

The field was rattled badly more recently when Pfizer noted that the high dose of their blockbuster JAK1/JAK3 inhibitor Xeljanz was linked to a higher rate of blood clots and death. That triggered regulatory warnings on both sides of the Atlantic as they reviewed the situation. And days ago Incyte announced that it will stop co-funding Olumiant as questions about the category abound.

One of the many questions now is whether the safety issue at Pfizer will bleed over to AbbVie, which has its own JAK1, upadacitinib, now under regulatory review for rheumatoid arthritis on both sides of the Atlantic. Gilead also has a lot riding on filgotinib, widely tapped as a potential blockbuster in its own right. 

And now Pfizer gets to join that major league crew.

Here’s what we know:

Their drug, designated a breakthrough therapy by the FDA, hit on the primary endpoint for the Investigator Global Assessment score of clear or almost clear skin and a ≥2 point improvement. The drug also scored on the proportion of patients who achieved at least a 75% or greater change from baseline in their Eczema Area and Severity Index (EASI) score. “The key secondary endpoints were the proportion of patients achieving a 4 point or larger reduction in itch severity measured with the pruritus numerical rating scale and the magnitude of decrease in the pruritus and Symptoms Assessment for Atopic Dermatitis.”

Discontinuation rates for the two doses tested were lower than in the placebo arm, but no details on adverse events were reported.

More Phase III results will be available later in the year.


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VP Oncology Biology
Skyhawk Therapeutics Waltham, MA
Associate Director CMC
Elektroki Boston, MA
Director Process Development
Elektroki Boston, MA
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Recursion Pharmaceuticals Salt Lake City, UT

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