The market for psoriatic arthritis therapies will grow nearly 66% by 2023, when it will be worth $3.7 billion, due to continued uptake of the premium-price biologics and novel therapies expected to launch over the period, say new forecasts.

In 2013, five marketed TNA-alpha inhibitors dominated the psoriatic arthritis (PsA) market, with over 90% of the $2.3 billion sales made in six major markets – US France, Germany, Italy, Spain, UK and Japan – led by AbbVie/Eisai’s Humira (adalimumab), says the study, from Decision Resources.

Over the next decade, TNF-alpha inhibitors will retain their sales-leading position, but two recently-launched treatments, Janssen’s Stelara (ustekinumab) and Celgene’s Otezla (apremilast), together with novel therapies – including the anti-interleukin-17 monoclonal antibodies secukinumab (Novartis), ixekizumab (Eli Lilly) and brodalumab (Amgen/AstraZeneca/Kyowa Hakko Kirin) and Pfizer’s Janus-kinase inhibitor Xeljanz (tofacitinib) – will account for approximately 21% of PsA treatment sales in these six markets in 2023, it says.

Of the five agents entering the market, Xeljanz will experience the greatest uptake to 2023, says DR. Xeljanz and Otezla feature oral formulations and unique mechanisms of action, allowing them to compete for TNF-alpha inhibitor-refractory patients, as well as experience uptake as “stop gaps” for conventional disease-modifying anti-rheumatic drug (DMARD) failures before stepping up to treatment with biologics.

The report also expects cheaper biosimilar versions of Humira, Pfizer’s Enbrel (etanercept) and Johnson & Johnson/Merck & Co’s Remicade (infliximab) to launch, starting in 2015. They will particularly erode sales of TNF-alpha inhibitors, accounting for 36% of their turnover for PsA by 2023. The clinical trial data for biosimilars in rheumatoid arthritis will reduce the barriers to their entry in the market, and most rheumatologists will fee comfortable prescribing them for PsA, it forecasts. 

Nevertheless, conventional DMARDs and TNF-alpha inhibitors remain the clinical mainstays for mild and moderate-to-severe PsA, respectively, and they will face only moderate loss of patient share to recently-launched and incoming novel therapies, say interviewed thought leaders.

Despite advances in the diagnosis and treatment of PsA, significant opportunity remains for developers of additional disease-modifying agents and products with a high degree of efficacy against multiple disease manifestations, comments DR group director Bingnan Kang.

“Physicians are keen for results of pivotal clinical trials of emerging PsA therapies. Interviewed thought leaders tell us that should ixekizumab and/or tofacitinib provide to be as or more effective than active comparator arms (versus adalimumab) in their respective Phase III trials, these therapies would experience stronger uptake compared with other novel agents entering the PsA market,” says Dr Kang.