Sales of drugs to treat psoriasis in seven major markets will increase from a value of $3.9 billion in 2010 to more than $7.4 billion by 2020, according to new forecasts.

This fast growth in the seven markets - the US, France, Germany, Italy, Spain, the UK and Japan - will be due to increases in drug treatment rates and the uptake of key current and emerging therapies, says the study, from Decision Resources.

Market growth will be driven by the continued uptake of Janssen Biotech/Janssen Cilag's Stelara (ustekinumab) and Abbott/Eisai's Humira (adalimumab), plus the launch and prescribing of two emerging therapies - Pfizer's tofacitinib and Novartis' secukinumab, it says.

These premium-priced agents are expected to replace less effective existing treatments and drive a rapid increase in sales of therapies for moderate-to-severe disease, which will account for the overwhelming majority of the psoriasis market in 2020, according to the study.

Amgen/Steifel/Pfizer/Takeda's Enbrel (etanercept) maintained its market dominance last year, earning $1.3 billion in sales for the treatment of psoriasis, but this drug will face stiff competition from Humira, Stelara and secukinumab, the report forecasts. This competition, combined with the entry of biosimilar formulations, will erode Enbrel's market share from one-third of total psoriasis sales in 2010 to less than one-fifth of sales in 2020, it adds.

"Humira will hold the position of market leader in 2020 with blockbuster sales of $2.1 billion," forecasts Decision Resources analyst Iva Holder. "Stelara, which launched in 2009, will rank second, garnering $1.5 billion in sales, exceeding those of Enbrel in 2017," she adds.

Stelara is an interleukin 12 and 23 (IL-12/23) inhibitor. Since its launch, uptake has been cautious, as a result of a limited long-term safety record and physicians' unfamiliarity with its mechanism of action. Recent data linking Abbott's emerging interleukin inhibitor briakinumab to incidences of major adverse cardiovascular events have strengthened dermatologists' cautious use of Stelara, but new studies suggest there are no significant differences in the rate of such events between patients in clinical trials treated with Stelara and those given placebo.

"Contingent on favourable postmarketing safety data, we forecast that Stelara will see some first-line biologic use ahead of the tumour necrosis factor (TNF)-alpha inhibitors by 2020," says Dr Holder.

The study also notes that tofacitinib has shown superb efficacy and has the potential to compete directly with available biologics for the treatment of moderate-to-severe psoriasis. However, it adds that the product's market potential will be restrained by the need to monitor patients for the occurrence of safety events such as increases in total cholesterol, low-density lipoprotein (LDL), high-density lipoprotein (HDL) and triglycerides, as well as by physicians' preference for the more familiar TNF-alpha inhibitors. 

Turning to secukinumab, the study says this product has also shown excellent efficacy in Phase II trials and that it is poised to threaten the treatment algorithm positioning of Stelara. Nevertheless, until a satisfactory postmarking safety record has been established, secukinumab will likely be used in patients who have already failed Stelara, it adds.