- Clinical trial results released Wednesday by Belgian drugmaker Galapagos and its partner Gilead Sciences, while positive, didn't meet what investment banks admitted were high expectations for the drug being studied.
- The results came from a late-stage trial testing two doses of filgotinib, as the drug is known, in two different types of ulcerative colitis patients. According to Gilead and Galapagos, a significantly higher proportion of patients achieved clinical remission after 10 weeks on the higher filgotinib dose when compared with placebo.
- Specifically, the higher dose group saw remission rates of 26% for patients who had never before taken a biologic medicine for their disease and almost 12% for those who had. In the placebo group, the remission rates were 15% and 4%, respectively. Wall Street analysts said the data should help secure an approval in ulcerative colitis — however, they don't know how much the results will help filgotinib stand apart from Pfizer's Xeljanz and AbbVie's Rinvoq, which work in similar ways and have shown similar efficacy in clinical trials.
Filgotinib has become a defining drug for Galapagos. It's what attracted Gilead when the companies began working together in 2015 — a partnership that since sprouted into a $5 billion research deal. It's also key to validating Galapagos' drugmaking capabilities.
Filgotinib had previously shown its merit in rheumatoid arthritis, as late-stage studies found it reduced joint swelling without eliciting some of the safety concerns which have weighed on its drug class, known as JAK inhibitors. Gilead, which holds U.S. rights to the drug, submitted it for approval as a rheumatoid arthritis treatment at the end of last year.
Galapagos, though, believes filgotinib can work across a wide range of immune conditions, including Crohn's disease, uveitis and psoriatic arthritis. Many studies testing the drug in these indications have paused enrollment due to the coronavirus pandemic. Fortunately for Galapagos, the Phase 2b/3 study in ulcerative colitis had already fully enrolled.
The results released Wednesday show the placebo-adjusted clinical remission rate was about 11% for biologic-naive patients on the 200 mg regimen of filgotinib and about 7% for patients who had before taken some kind of biologic. While these were significantly better than the placebo group, the lower, 100 mg dose didn't fare as well by week 10.
The incidence of serious adverse events, meanwhile, was similar across all three groups. Importantly, rates of venous thrombosis and pulmonary embolism, which are two of the safety issues that have loomed over JAK drugs, were "low and comparable across treatment groups in both the induction and maintenance phases of the study," according to the companies.
While hard to compare because of differences in design, patient enrollment and the definition of "clinical remission," the new efficacy data for filgotinib appear roughly on-par with what other JAK inhibitors have shown in ulcerative colitis.
Xeljanz, which was approved for the disease in 2018, showed placebo-adjusted efficacy of 10% to 14% in biologic-naive patients and 8% to 12% in biologic-experienced patients, according to RBC Capital Markets analyst Brian Abrahams. AbbVie's Rinvoq, which was recently cleared for rheumatoid arthritis, had placebo-adjusted remission rates of 6% to 11% in biologic-experienced patients
As such, filgotinib was "not a standout winner, but not a loser either" following its latest ulcerative colitis data, according to Abrahams. RBC models around $4 billion in peak sales for filgotinib across all its potential indications. Investment bank Stifel, meanwhile, predicts that filgotinib at its peak could fetch $4 billion from ulcerative colitis alone.
Others, however, took a more critical view.
Analysts at Credit Suisse covering Arena Pharmaceuticals wrote that the filgotinib data were "largely underperforming efficacy expectations" for the JAK inhibitor class in ulcerative colitis. Arena, notably, is developing a rival ulcerative colitis medicine called etrasimod that works in a different way than JAKs to reduce inflammation.
Galapagos shares were down more than 7% Thursday morning, while Gilead's were relatively unmoved.