Eli Lilly and Company, a global healthcare leader,  announced that the investigational medicine ixekizumab was statistically superior to placebo in the treatment of patients with active psoriatic arthritis (PsA), as demonstrated by the proportion of patients achieving an ACR 20 response. ACR 20 is a standard assessment that represents a 20 per cent reduction in disease signs and symptoms as defined by the American College of Rheumatology response criteria.

During the 24-week, phase 3 study, titled SPIRIT-P1, patients who were naïve to biologic disease-modifying antirheumatic drugs (bDMARD) were treated with one of two different ixekizumab dosing regimens or placebo. In both dosing regimens, ixekizumab-treated patients demonstrated significant improvements versus placebo in signs and symptoms of active PsA.

PsA is a progressive, chronic and destructive disease that can cause swelling, stiffness and pain in and around the joints, nail changes, and impaired physical function. It is one of the most common rheumatic arthritides, occurring within 0.3 to 1 per cent of the general population, and in up to approximately 30 per cent of people with psoriasis.

"Psoriatic arthritis is a debilitating disease associated with progressive joint damage and skin involvement, and also has a significant impact on a person's quality of life," said J. Anthony Ware, M.D., senior vice president, Lilly Bio-Medicines Product Development. "These results strengthen our belief that ixekizumab may have the potential to help people confronting this challenging disease."

In SPIRIT-P1, the incidence of treatment-emergent adverse events was more frequent with ixekizumab compared with placebo. The most common adverse events observed were consistent with the Phase 3 studies of ixekizumab for the treatment of moderate-to-severe plaque psoriasis. The rates of serious adverse events with ixekizumab treatment were similar to placebo. Discontinuation rates due to adverse events were similar between treatment groups.

Lilly plans to submit detailed data from the SPIRIT-P1 study for disclosure at scientific meetings and in peer-reviewed journals.

SPIRIT-P1 is a phase 3 randomized, active- and placebo-controlled study examining the effect of ixekizumab compared with placebo in patients with active PsA who are bDMARD-naïve. Patients were required to have an established diagnosis of PsA and active disease for at least six months. During the study, ixekizumab-treated patients received a starting dose of 160 mg administered subcutaneously (SC), followed by one of two dosing regimens: either 80 mg administered SC once every two weeks or 80 mg administered SC once every four weeks. Adalimumab at the approved dose of 40 mg SC and regimen of every other week was selected as the active control for comparison with placebo. The SPIRIT-P1 study will also evaluate the long-term efficacy and safety of ixekizumab in PsA for up to three years.

Ixekizumab is a monoclonal antibody with high affinity and specificity that binds to and neutralizes the pro-inflammatory cytokine interleukin-17A (IL-17A), which research has shown can contribute to autoimmune diseases, including PsA and psoriasis. Ixekizumab does not bind to cytokines IL-17B, IL-17C, IL-17D, IL-17E or IL-17F and is administered via subcutaneous injection (under the skin). Ixekizumab is also in clinical development for the treatment of moderate-to-severe plaque psoriasis.