FDA approval of siliq for psoriasis – how will the drug perform in an already overcrowded market?


The FDA approval of Valeant’s Siliq (brodalumab) marks the third interleukin-17 (IL-17) inhibitor to launch for psoriasis in the US since the approval of Novartis’ Cosentyx (secukinumab) in January 2015. IL-17 inhibitors face competition from two other biologic drug classes approved for psoriasis, anti-tumor necrosis factor therapies and IL-12/23 therapies, not to mention the introduction of biosimilars. That being said, in 2024, with all approved drugs trying to jockey for position and stand out among the rest, GlobalData’s forecast shows that IL-17 inhibitors will gross an estimated $1.9 billion in total US drug sales (see Figure 1 below).

Figure 1: US Sales for Interleukin-17 Inhibitors, 2015-2024

Psoriasis is a chronic autoimmune skin disease defined by visible lesions, most commonly developing on the scalp, trunk, buttocks, elbows, and knees. If left untreated, patients may suffer from itching, burning, soreness, and bleeding skin. For psoriasis, the last six years have seen an influx of novel treatments outside the mainstay anti-tumor necrosis factor therapies, including Johnson & Johnson’s Stelara (ustekinumab), an IL-12/IL-23 inhibitor; Celgene’s Otezla (apremilast), a phosphodiesterase-4 inhibitor; Novartis’ Cosentyx, the first-to-market IL-17A inhibitor; and Eli Lilly’s Taltz (ixekizumab), another IL-17A inhibitor.

Although IL-17 inhibitors are newcomers to the psoriasis market, Cosentyx is a first-line biologic for the treatment of psoriasis, given its improved efficacy over other approved biologics. Cosentyx and Taltz have already started making a big impact on the market. According to GlobalData, Cosentyx and Taltz are on their way to gaining blockbuster status with forecast US sales of $722m and $677m, respectively, by 2024.

In spite of Siliq’s earlier developmental setback due to safety concerns around increased suicidal tendencies, Siliq remains slated for success in the crowded psoriasis therapy space. Although Siliq was approved with a boxed warning for patients with a history of suicidal ideation and a Risk Evaluation and Mitigation Strategy, Siliq will make a name for itself in the IL-17 market as the first monoclonal antibody to block the IL-17 receptor. Despite the competition, GlobalData’s psoriasis report shows Siliq is expected to generate sales of $469m in the US psoriasis market alone by 2024, marking a substantial opportunity for Valeant.