Eli Lilly and Incyte said today that their experimental rheumatoid arthritis (RA) drug baricitinib met its primary endpoint in the Phase III RA-BEACON trial—the first of several pivotal studies assessing the once-daily, oral, selective JAK1 and JAK2 inhibitor.

Baricitinib yielded RA improvement of at least 20% based on American College of Rheumatology criteria (ACR20) compared to placebo after 12 weeks of treatment, the companies said.

“These results give us further confidence in the potential for baricitinib to be a meaningful treatment option for those suffering from this debilitating condition,” David Ricks, Lilly svp and president, Lilly Bio-Medicines, said in a statement.

Added Rich Levy, M.D., Incyte’s chief drug development and medical officer: “We are very pleased by these results.”

RA-BEACON enrolled 527 patients who had previously failed at least one antitumor necrosis factor (TNF) therapy, and included a “high” percentage who had also received prior treatment with one or several nonanti-TNF biologic agents, the companies said. Patients received either one of two doses of once daily baricitinib or placebo in addition to their background conventional disease-modifying anti-rheumatic drug therapy (cDMARDs).

Incidence of serious adverse events with baricitinib, including serious infections, was similar to placebo. No opportunistic infections or gastrointestinal perforations was seen among patients. However, trial results also showed a higher incidence of treatment-emergent adverse events with baricitinib compared to placebo.

The most common adverse events observed with baricitinib were headache, upper respiratory tract infection, and nasopharyngitis. Discontinuation rates due to adverse events were similar between treatment groups. According to Lilly and Incyte, a “large” majority of patients completing RA-BEACON opted to participate in a long-term extension study.

RA-BEACON is part of the companies’ Phase III program for baricitinib. More than 3,000 people with rheumatoid arthritis have been enrolled in the studies—four in the U.S., one in China. According to Lilly and Incyte, the clinical trial program includes a wide range of patients including those who are methotrexate naïve, inadequate responders to methotrexate, inadequate responders to conventional disease-modifying antirheumatic drugs, or inadequate responders to TNF inhibitors.

“Over the next 12 months we look forward to seeing the data from additional Phase III studies of baricitinib in rheumatoid arthritis, including patients who have had an inadequate response to conventional DMARDs and in those with earlier stage disease,” Dr. Levy added.

Incyte and Lilly envision multiple indications for baricitinib linked to inflammatory and autoimmune disease. In addition to Phase III clinical development for rheumatoid arthritis, baricitinib is currently in Phase II studies for psoriasis and diabetic nephropathy.

The initial positive Phase III results come five years into a collaboration between the companies to develop Incyte’s JAK1/JAK2 inhibitors. Lilly has joined Incyte in co-developing baricitinib through an exclusive up-to-$755 million-plus worldwide license and collaboration agreement signed in 2009.

Lilly agreed to pay Incyte $90 million upfront and up to $665 million in payments tied to milestones, as well as royalties on future sales. In return, Incyte has retained co-development and co-promotion options to the compound, initially known as INCB28050. The agreement also includes unspecified follow-on compounds for patients with inflammatory and autoimmune diseases.

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