US regulators have expanded the scope of Eli Lilly’s plaque psoriasis drug Taltz to include the treatment patients with psoriatic arthritis.

Taltz (ixekizumab) is an antibody that binds to interleukin-17A, a protein that causes inflammation and plays a role in the development of these conditions.

The drug is administered as an injection, either alone or in combination with a conventional disease-modifying antirheumatic drug such as methotrexate.

Its efficacy and safety in the psoriatic arthritis setting was demonstrated in two randomised, double-blind, placebo-controlled Phase III studies - SPIRIT-P1 and SPIRIT-P2 - which involved more than 670 adult patients with active disease.

In SPIRIT-P1, which evaluated the safety and efficacy of Taltz compared to placebo in patients with active PsA who had never been treated with a biologic disease-modifying antirheumatic drug, 58 percent of patients treated with the drug achieved an ACR20 response (a 20 percent reduction in a composite measure of disease activity) versus 30 percent for placebo.

In SPIRIT-P2, which pitted Taltz against placebo in tumor necrosis factor inhibitor (TNFi)-experienced patients with active PsA who failed one or two TNF inhibitors, the ACR20 responses were 53 percent and 20 percent, respectively.

"PsA is a chronic, progressive and painful form of inflammatory arthritis that impacts approximately 1.6 million Americans living with the disease," said Christi Shaw, president, Lilly Bio-Medicines.

"We are proud to offer a new treatment option that can provide improvements in joint symptoms for these patients, further demonstrating Lilly's overall commitment to immunology."