CHICAGO – The selective Janus kinase 1 inhibitor filgotinib showed efficacy and safety for patients with rheumatoid arthritis in a phase 3 trial, and efficacy and safety for treating patients with psoriatic arthritis in results from a phase 2 study in two separate reports at the annual meeting of the American College of Rheumatology.
In the phase 3 study, treatment with filgotinib at an oral dosage of 200 mg once daily led to a 66% incidence of American College of Rheumatology 20 (ACR20) responses after 16 weeks of treatment in 147 patients with moderately to severely active rheumatoid arthritis (RA), compared with a 31% rate among 148 patients randomized to receive placebo, a statistically significant improvement for the study’s primary efficacy endpoint,, reported in a at the meeting. The rate of ACR20 responses among the 153 RA patients who received 100 mg/day filgotinib was 58%, reported Dr. Genovese, professor of medicine and director of the rheumatology clinic at Stanford (Calif.) University.
After 24 weeks of daily treatment, the longest duration studied in the trial, ACR20 rates were 69%, 55%, and 35% in the 200-mg, 100-mg, and placebo patients, respectively. Dr. Genovese also reported that after 24 weeks on treatment, the rates of patients achieving low disease activity measured by their disease activity score based on 28 joints and C-reactive protein level (DAS28-CRP) were 48%, 38%, and 21%, respectively, and the percentages of patients achieving complete remission at 24 weeks based on their DAS28-CRP scores were 31%, 26%, and 12%, respectively.
“We were incredibly fortunate to see such positive results. The drug worked very well in very-challenging-to-treat patients,” Dr. Genovese said in an interview. All of the RA patients enrolled in the study had not previously responded to or were intolerant of prior treatment with at least one biologic disease-modifying antirheumatic drug (DMARD), and almost a quarter of enrolled patients had failed prior treatment with at least three different biologic DMARDs. The number of biologic DMARDs a patient had previously received showed no relationship to how well patients responded to filgotinib, he noted.
Dr. Genovese also highlighted the relatively high percentage of patients who achieved low disease activity and remission. The 48% and 31% rates, respectively, of low disease activity and remission among patients treated with the higher filgotinib dosage for 24 weeks “is fairly impressive in patients who did not previously respond to a biologic DMARD,” the researcher said. These findings are similar to data previously reported for upadacitinib, another Janus kinase (JAK) inhibitor that, like filgotinib, is selective for the JAK1 receptor, noted Dr. Genovese, who also was the lead investigator for a phase 3 study of upadacitinib in RA patients ().
The filgotinib data he presented came from the(Filgotinib Versus Placebo in Adults With Active Rheumatoid Arthritis Who Have an Inadequate Response to Biologic Disease-Modifying Anti-Rheumatic Drug[s] Treatment) trial, which was run at 104 sites in 15 countries, including the United States. The results also showed a “favorable safety profile and stable laboratory parameters,” Dr. Genovese reported. Results from two additional phase 3 trials in RA patients are expected in 2019, he said.