Evaluating New Treatments in PsA: Why We Need to Use the Right Tools

The definition for psoriatic arthritis was recently broadened to include inflammatory enthesitis, in addition to inflammatory arthritis and/or spondylitis. Since most patients have peripheral arthritis, PsA has been traditionally viewed through the 'RA lens.' Thus, the traditional drugs to manage PsA and the tools to assess treatment efficacy have all been borrowed from RA.

The trend continued with TNFi since these agents were efficacious in RA as well as PsA (and other inflammatory diseases). The availability of efficacious agents spurred research into better outcome measures that take into account the spectrum of manifestations in PsA. It is now recommended that enthesitis and dactylitis should be evaluated in addition to peripheral arthritis and psoriasis.

Composite indices specific to PsA, such as PASDAS, GRACE index, CPDAI and DAPSA, have also been developed. New trials in PsA are now beginning to use these measures in addition to traditional RA outcome measures such as ACR20/50/70 and DAS28.

The results from a number of trials for novel treatment agents will be presented at this year's ACR including agents efficacious in RA (abatacept, tofacitinib) as well as agents that are or may not be (guselkumab, secukinumab, ixekizumab, ABT-122). When we critically evaluate information from these trials in PsA, it is important to evaluate how these drugs improve not only arthritis but also domains such the skin, enthesitis and dactylitis, and whether the outcome measures used are valid in PsA.

How do the trials stack up?

The trial with guselkumab, an anti-IL-23 MAb with proven efficacy in psoriasis, includes outcome measures such as ACR20/50/70, measures of skin psoriasis, enthesitis, dactylitis as well as the composite measures PASDAS, GRACE, CPDAI, DAPSA and MDA.

The trials with tofacitinib, secukinumab, and ixekizumab assessed ACR 20/50/70 responses as well as skin psoriasis, enthesitis and dactylitis, but the newer composite measures were not evaluated (or reported).

The trial with abatacept did not report enthesitis, dactylitis or composite measures, and only PASI50 (not PASI75) assessed skin response. Surprisingly, the study with ABT-122 reports ACR 20/50/70 as well as PASI75, but reports LDA and CR rates based on DAS28 (hsCRP), which are composite measures used in RA, but not validated in PsA.

The lack of uniformity in reporting clinical trial results in PsA makes it challenging for practicing rheumatologists to understand the efficacy of these agents in PsA. A consensus on reporting PsA trial endpoints will go a long way in assessing as well as comparing across studies.

Thank you to Dr. Vinod Chandran for writing this sponsored RheumReport.

Sponsored Content This RheumReport is sponsored by Celgene Inc.

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