MAUI, HAWAII – Filgotinib, the oral Janus kinase (JAK) inhibitor now under Food and Drug Administration review for the treatment of RA, has a better safety profile than some of the approved oral JAK inhibitors, but that’s unlikely to save it from being saddled with a black-box safety warning label, experts agreed at the 2020 Rheumatology Winter Clinical Symposium.
Bruce Jancin/MDedge News
Dr. Roy Fleischmann (L) and Dr. Mark C. Genovese
“There’s probably a class label out there,” according to Mark C. Genovese, MD, professor of medicine and clinical chief of the division of immunology and rheumatology at Stanford (Calif.) University.
He cited the example of upadacitinib (Rinvoq), approved last year as the third oral JAK inhibitor for RA. Even though venous thromboembolic (VTE) events weren’t seen with any significantly increased frequency, compared with placebo, in the upadacitinib development program – unlike for the earlier-approved tofacitinib (Xeljanz) and baricitinib (Olumiant) –the FDA nevertheless required that upadacitinib’s product labeling include this black-box warning: “Thrombosis, including deep vein thrombosis, pulmonary embolism, and arterial thrombosis, have occurred in patients treated with Janus kinase inhibitors used to treat inflammatory conditions.”
“I would fully expect that there’ll be a similar label in the filgotinib package insert saying that VTEs have been seen in other members of the class,” he predicted.
His copanelist Roy Fleischmann, MD, noted that filgotinib displayed a clean long-term safety profile in a pooled analysis of the 24-week results in the 2,088 filgotinib-treated participants in all phase 3 clinical trials for RA. For example, the incidence of herpes zoster in that large treated population was a mere 0.1%.
“Herpes zoster is almost nonexistent across the program,” observed Dr. Fleischmann, a rheumatologist at the University of Texas and medical director of the Metroplex Clinical Research Center, both in Dallas.
That’s consistent with what he’s heard from Japanese investigators about their experience. They tell him that in their studies the incidence of herpes zoster with filgotinib is five times less than with other JAK inhibitors.
The long-term pooled phase 3 filgotinib safety data also show less than a 0.1% incidence of adjudicated VTE/pulmonary embolism through 24 weeks. That’s a substantially lower rate than with tofacitinib or baricitinib, he noted.
The two rheumatologists, long-time observers of the FDA regulatory scene, stressed that they have no inside information regarding what the agency will do about filgotinib. It seems beyond doubt that the JAK inhibitor will be approved. But an open question of practical importance to clinicians is whether the agency will approve only the 100-mg dose or the 200-mg dose as well. The panelists agreed that having access to both would be advantageous since the clinical trials data indicate the higher dose is more effective and this greater efficacy doesn’t come at a cost of additional safety issues.
“If the 100 mg is sufficient, that’s great, but the reality is if you want to push to low disease activity or remission, the 200 mg seems to work better, particularly in patients who’ve already failed TNF [tumor necrosis factor] inhibitors or other biologics,” Dr. Genovese said. “If you’re not having additional safety concerns and you can get additional efficacy, I love the idea of having flexibility.”
Dr. Fleischmann is skeptical that the regulators will see things that way.
“There is a real risk that the FDA will do what it’s done before and say: ‘Well, the 200 works and the 100 works, so we’re going to approve the lower dose.’ But there doesn’t appear to be a big safety difference between 100 and 200. So I can see why they would approve the two doses, but I think that’d be unusual,” according to the rheumatologist.