COPENHAGEN – Baricitinib (Olumiant), a Janus kinase (JAK) inhibitor, significantly increases time to disease flare and decreases frequency of flares in patients with juvenile idiopathic arthritis (JIA), according to the results of a phase 3, placebo-controlled study.

The results support use of baricitinib when biologic or conventional synthetic disease-modifying antirheumatic drugs (DMARDs) fail.

The difference in the proportion of patients who flared between baricitinib and placebo was seen as soon as 4 weeks after half of the patients switched from active drug to placebo, at 3.7% versus 23.5% respectively, reported Athimalaipet Ramanan, MD, from the University of Bristol (England) who presented the findings of the withdrawal, efficacy, and safety study at the annual European Congress of Rheumatology.

“Our patients and parents have been waiting for alternative drugs for JIA, so JAK inhibitors have come at the right time,” he said. “These are really very encouraging findings for families, caregivers, and patients with JIA, to have an effective oral JAK inhibitor for managing these children.”

In reporting the key findings, Dr. Ramanan added that the majority of patients (76%) achieved a JIA-ACR (American College of Rheumatology) 30 score during the 12-week open-label phase and went on to enter the double-blind withdrawal phase of the trial.

Baricitinib 2-mg tablets are already Food and Drug Administration approved for the treatment of adults with moderately to severely active rheumatoid arthritis. This study, sponsored by the drug manufacturer Eli Lilly, aimed to investigate the efficacy and safety in pediatric patients with JIA who have shown an inadequate response to conventional synthetic or biologic DMARDs.

“For juvenile patients we need to make a dose adjustment [from the adult dosing], especially because we don’t have long-term safety data from JAK inhibitors in general,” said Osama Elfayad, MD, rheumatologist from Mouwasat Hospital, Dammam, Saudi Arabia who attended the presentation and commented on the findings.

He emphasized that safety was of primary concern in the pediatric population who have a long life expectancy. “For me it is essential to have good long-term safety data in juvenile patients. If we start with 4 mg and if the patient is controlled, we should shift to 2 mg which will be much better. I understand some clinicians are asking for 1 mg.”

Study details

The study population included patients aged from 2 to 17 years old with extended oligo- or polyarticular JIA, enthesitis-related juvenile idiopathic arthritis (ERA) and juvenile psoriatic arthritis.

The trial was divided into three periods: a 2-week safety assessment, a 12-week open-label lead-in phase, and an up-to 32-week double-blind withdrawal phase. After confirmation of dose and safety, children were enrolled in the open-label phase receiving age-based, oral, once daily doses of baricitinib.

“The primary endpoint is really concerned with the next phase of the study [double-blind withdrawal phase] looking at the proportion of patients who have shown a response at week 12 [achieved JIA-ACR30] but when switched from active drug to placebo have a flare,” explained Dr. Ramanan.

Patients were randomized 1:1 to continuing baricitinib or newly starting placebo until disease flare or up to week 32. The time to flare during the double-blind phase was the primary endpoint, while secondary endpoints included JIA-ACR30/50/70/90 response rates at week 12, and the proportion of patients with a flare during the double-blind phase.

“These secondary endpoints are more relevant to the clinic,” noted Dr. Ramanan.

A total of 219 patients entered the open-label phase, and of these, 163 achieved a JIA-ACR 30. These 163 children entered the double-blind stage and were randomized to baricitinib four times a day (56 completed), or placebo (32 completed).

Two-thirds of patients were female, which is typical of the disease, explained Dr. Ramanan, and over two-thirds were White. “Most patients had had disease for around 4 years, and about half had had prior biologic therapy. About half were on baseline methotrexate and almost one-third had used corticosteroids although at doses of under 0.2mg/kg.

“It’s gratifying to see that over 75% achieved a JIA-ACR 30 [76.3%]. More importantly, two-thirds of the patients have a JIA-ACR 50 [63.5%], and almost half of the patients have a JIA-ACR 70 [46.1%]. This is pretty significant at 12 weeks only,” he remarked.

The key finding, however, was in the withdrawal phase, said Dr. Ramanan. “We see that those patients who had a response at week 12 and were then switched to placebo, about half [50.6%] flared on placebo, compared to only 17% of those who continued with baricitinib. So not only do those who switch to placebo have a higher frequency of flares but they are more likely to flare quickly, as early as 4 weeks.”

With respect to safety, he said: “This shows short-term safety, but what we really need is medium and long-term safety data. It is no surprise that most of the events seen were as expected in children including nasopharyngitis, upper respiratory tract infections, and nausea.”

In the baricitinib versus placebo phase, 4.9% had serious adverse events in the baricitinib group compared to 3.7% in the placebo group. “There was nothing we didn’t expect to see which was mainly infection,” said Dr. Ramanan.

Dr. Elfayad has no disclosures. Professor Ramanan is a consultant for Eli Lilly, Abbvie, Roche, UCB, Novartis, Pfizer, and Sobi. He has received grant/research support from Eli Lilly.

‘Encouraging’ results of baricitinib in juvenile idiopathic arthritis