What happened

Shares of Galapagos NV (GLPG -0.57%) were soaring 17.6% higher as of 11:04 a.m. EDT on Friday. The biotech and its big partner, Gilead Sciences (GILD -0.85%), announced positive results from two late-stage clinical studies evaluating filgotinib in treating rheumatoid arthritis as well as updated safety results for the experimental drug in multiple clinical trials.

So what

The biggest news for Galapagos and Gilead was that filgotinib met the primary and secondary endpoints in the phase 3 Finch 1 study in treating rheumatoid arthritis. Filgotinib went head-to-head against AbbVie's Humira, the top-selling drug in the world, and came out on top. The drug had previously been successful in the phase 3 Finch 2 study.

Two people in a lab with one looking through a microscope

Image source: Getty Images.

Galapagos and Gilead also reported that filgotinib met the primary endpoint in the phase 3 Finch 3 clinical study. In this study, both 100-milligram and 200-milligram doses of filgotinib in combination with methotrexate as well as a 200-milligram dose of filgotinib as a monotherapy achieved greater improvement in rheumatoid arthritis patients than methotrexate alone.

In addition, the two biotechs provided updated safety data from four studies of filgotinib, including three phase 3 Finch trials and the phase 2b Darwin 3 long-term extension study. This data bolstered the chances that filgotinib's safety profile will be satisfactory to regulators in the future.

Actually, all of the updates from Galapagos and Gilead on Friday appeared to point to great prospects for filgotinib to ultimately win regulatory approvals. And that's why Galapagos stock jumped so much. The biotech doesn't have any approved products on the market yet. Filgotinib is its lead pipeline candidate. Gilead Sciences investors were also encouraged by the positive results, with shares of the big biotech rising 2.7% higher as of 11:04 a.m. EDT on Friday.

Check out the latest earnings call transcripts for Gilead Sciences and other companies we cover.

Now what

Although everything is looking great for filgotinib, don't expect a regulatory filing to the U.S. Food and Drug Administration (FDA) anytime soon. Gilead Sciences Chief Scientific Officer John McHutchison stated in the company's Q4 conference call in February that data from the Manta safety study of filgotinib in treating men with ulcerative colitis will be required before submitting the drug for FDA approval.

However, positive results from the Finch studies will enable Gilead and Galapagos to potentially move forward with regulatory filings outside of the U.S. This data should also allow the companies to meet with the FDA and be able to provide more details on when a U.S. filing for filgotinib could be submitted.