Lilly’s ixekizumab demonstrates efficacy in psoriatic arthritis

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Psoriatic arthritis (PsA) patients treated with Lilly’s ixekizumab for 24 weeks achieved significant improvements in signs and symptoms of their disease when compared to placebo.

PsA patients treated with ixekizumab also experienced significantly less progression of radiographic structural joint damage, reduced disability when performing certain physical functions and improved skin clearance of plaque psoriasis.

Ixekizumab is the company’s investigational medicine for the treatment of active PsA and moderate-to-severe plaque psoriasis.

“The SPIRIT-P1 data show that ixekizumab may be able to address unmet or underserved needs that many patients living with psoriatic arthritis have, including the reduction of painful and debilitating skin and joint inflammation, which are the hallmarks of this chronic disease,” said Philip Mease, M.D., chief of rheumatology research, Swedish Medical Centre, and clinical professor, University of Washington, Seattle. Dr. Mease is a SPIRIT-P1 study investigator.

During the 24-week, double-blind period of this Phase 3 study, patients who had never received a biologic disease-modifying antirheumatic drug (bDMARD) were treated with either 80 mg of ixekizumab once every two weeks or every four weeks (following a 160 mg starting dose); adalimumab at the approved dose of 40 mg every other week; or placebo. Adalimumab was employed as an active control in the SPIRIT-P1 study and was not powered for comparison with ixekizumab treatment groups.

In both dosing regimens, ixekizumab-treated patients demonstrated significant improvements compared with placebo in disease activity of PsA as demonstrated by the proportion of patients achieving an ACR20 response at 24 weeks, the study’s primary objective. Improvements were experienced by ixekizumab-treated patients as early as one week after treatment initiation. ACR20 represents at least a 20% reduction in a composite measure of disease activity as defined by the ACR.

At 24 weeks, 62 percent of patients treated every two weeks and 58 percent of patients treated every four weeks with ixekizumab achieved ACR20 compared with 30%  of placebo-treated patients. The proportions of ixekizumab-treated patients who achieved ACR50 when treated every two weeks or every four weeks were 47% and 40%, respectively, compared with 15% of patients treated with placebo. Furthermore, 34% of patients treated with ixekizumab every two weeks and 23%of those treated every four weeks experienced a 70% reduction in disease activity. Six percent of patients treated with placebo achieved this level of improvement.

Ixekizumab treated patients experienced less radiographic progression of structural joint damage

Patients treated with ixekizumab at both dosing regimens also experienced significantly less radiographic progression of structural joint damage than those treated with placebo, as measured by the change from baseline in the van der Heijde modified total Sharp score (mTSS) for PsA at 24 weeks. Structural joint damage caused by PsA may lead to permanent joint deformity and reduced physical function.
Ixekizumab treatment groups also experienced significant improvements compared with placebo in other key secondary measures, including physical function as assessed using the Health Assessment Questionnaire Disability Index (HAQ-DI), and improved skin clearance of plaque psoriasis as measured by the Psoriasis Area and Severity Index (PASI), including PASI75, 90 and 100.

“Many people living with this debilitating disease are still searching for an effective treatment,” said J. Anthony Ware, M.D., senior vice president, product development, Lilly Bio-Medicines. “These results further support our continuing investigation of ixekizumab for the treatment of psoriatic arthritis, and our belief that this investigational medicine may offer a viable choice in the future for people seeking a better way to manage their disease.”