Dive Insight:

Galapagos is under considerable pressure to make filgotinib succeed. Not only is it Galapagos’ most advanced drug — and, by extension, a bellwether of the company’s research and development skills — but it’s also the crux of a $5 billion research pact inked with Gilead in 2019.

Similar to marketed drugs like Pfizer’s Xeljanz, AbbVie’s Rinvoq and Eli Lilly’s Olumiant, filgotinib works by blocking a certain kind of enzyme that spurs inflammation. Though this drug class has proven effective at treating conditions ranging from rheumatoid arthritis to inflammatory bowel disease, it also has safety concerns.

The labels for Xeljanz, Rinvoq and Olumiant, for example, all carry warnings about serious infection, blood clots and malignancy. And earlier this year, a large study found patients given Xeljanz experienced health issues like major heart complications and cancer at a higher incidence than those who got a different kind of anti-inflammation drug.

For filgotinib, the safety concerns were significant enough that the Food and Drug Administration turned down Gilead’s attempt to get it approved as a rheumatoid arthritis treatment. According to Gilead, the FDA questioned whether the benefits of the higher, more effective dose of filgotinib outweighed the risks, and also asked for data from the two ongoing testicular health studies.

Following the rejection, Gilead pulled away from the filgotinib program. The company announced late last year that it would not try again to secure a rheumatoid arthritis approval in the U.S., and that it had handed back to Galapagos rights to develop, manufacture and commercialize the drug in Europe.

Against that backdrop, analysts see the initial data from the testicular health studies as a much-needed bright spot for the filgotinib program. “While the magnitude of the sperm count reduction is surprising, the roughly balanced effect between drug and placebo arms is reassuring,” wrote SVB Leerink analyst Geoffrey Porges.

The big question, though, is how much those data will end up benefiting Galapagos, given the prior setbacks as well as the market competition from Pfizer, AbbVie and Lilly.

“We believe this should take the worst-case scenario off the table,” wrote Brian Abrahams, an analyst at RBC Capital Markets, in a note to Galapagos investors. But, “whether the detailed data will satisfy FDA’s concerns — and, even if they do whether [Gilead] would try to launch the drug in select indications in the U.S. anyway, given the competitive landscape — remains unclear.”

In Europe, regulators first approved Jyseleca last fall for patients with moderate to severe rheumatoid arthritis. Now, they’re also reviewing it as a treatment for ulcerative colitis. Dane Leone, an analyst at Raymond James, believes the interim data from the testicular health studies “bodes well,” both for that review and Galapagos’ peak sales estimate of 500 million euros for the drug.