The Promise of New Therapies in PsA and AxSpA

Two-three percent of people in the general population live with psoriatic arthritis, but many of them go undiagnosed, says Christopher Ritchlin, M.D., University of Rochester Medical School. Doctors are racking their brains trying to figure out how to reach this population, he said during a presentation at the Rheumatology Nurses Society annual conference held earlier this month in Cleveland.

Skin psoriasis precedes the onset of psoriatic arthritis (PsA) in 84% of patients, studies show. A meta-analysis published in an August 2015 issue of the Journal of the American Academy of Dermatology, found that the prevalence of undiagnosed PsA in patients with psoriasis ranged between 10 and 15%, but other studies show that it can affect up to 25% of patients who are usually treated by a dermatologist.

“It is critical that we diagnose patients early,” Dr. Ritchlin said. “We are struggling to work with dermatologists to have these patients re-evaluated by a rheumatologist. If you defer a diagnosis, this is what can happen,” he said pointing to a slide with pictures of advanced psoriatic arthritis. A delay in diagnosis of six months can lead to erosive disease, deformed joints, arthritis mutilans, sacroiliitis, functional disability and it can negatively affect a patient’s chance of reaching drug free remission, he said.

Dr. Ritchlin, a rheumatologist who specializes in psoriatic arthritis began his practice in the 1980s when few medications were available to treat psoriatic arthritis. Back then, physicians largely relied on drugs designed for rheumatoid arthritis, but patients showed little signs of improvement. Scientists would later learn that joint inflammation in psoriatic arthritis differs from that of rheumatoid arthritis (RA). In RA, the inflammation usually begins in the synovial lining, but in PsA the onset can be identified by changes in bone structure.

Psoriasis patients who develop PsA, can develop other comorbidities, including uveitis, hypertension, cardiovascular disease, osteoporosis, gastrointestinal disorders, steatosis, malignancies, obesity and metabolic syndrome. A large number of these patients are not receiving regular treatment, said Dr. Ritchlin referring to the results of the recent MAPP survey.

MAPP - or, the Multinational Assessment of Psoriasis and Psoriatic Arthritis (MAPP) - survey was a telephone survey conducted in households from the United States, Canada, United Kingdom, France, Germany, Italy and Spain with the goal of understanding what type of therapies patients with psoriasis and psoriatic arthritis were receiving.

“What’s striking about this survey was that even in patients with severe psoriasis or psoriatic arthritis, the number of patients on systemic therapies of any type was extremely rare as compared to patients who were either on topicals or no therapy. I think this study underscores the fact that there are a large number of patients in the community who are not receiving any systemic treatment at all for these diseases, which can have major effects on function and quality of life,” he said.

The Promise of New Therapies

Psoriatic arthritis and axial spondyloarthritis (AxSpA) share some of the same disease pathways and mechanisms and Dr. Ritchlin speculates that PsA and AxSpA may be a continuum of the same disease.

“Targeting IL-12, IL-23 or IL-17 is an effective strategy for both psoriatic arthritis and the axial spondyloarthropathies,” he said.

The field shows great promise for new treatments in coming years, especially for treatments that target the IL-23 pathway, Dr. Ritchlin said. Many promising new therapies targeting IL-23 are in pre-clincal or phase II clinical trials.

New Treatment Guidelines

Three sets of recommendations have been released for PsA in recent months. EULAR issued treatment recommendations for psoriatic arthritis, which were followed by PsA treatment guidelines issued by the Group for Research and Assessment of Psoriasis and Psoriatic Arthritis (GRAPPA) 2015 Treatment Recommendations for Psoriatic Arthritis, of which Dr. Ritchlin was a co-author.

The two sets of recommendations differ in one area in that GRAPPA formulated their recommendations around the five different domains: 

·        Skin and Nails

·        Peripheral arthritis

·        Axial disease

·        Dactylitis

·        Enthesitis

·        (And, it included an additional domain of comorbidities.)

References:

Villani AP, Rouzaud M., et al.  “Prevalence of undiagnosed psoriatic arthritis among psoriasis patients: Systematic review and meta-analysis.” J Am Acad Dermatol. 2015 Aug;73(2):242-8. DOI: 10.1016/j.jaad.2015.05.001. Epub 2015 Jun 6.