The recognition of the roles of interleukins (IL)-12 and IL-23 in the 
development of psoriasis is an important advance in the understanding, and the 
subsequent management, of this chronic inflammatory disease. Two human anti-p40 
monoclonal antibodies targeting both IL-12 and IL-23 via their shared p40 
subunit have been developed: briakinumab and ustekinumab. Recent Phase 2 and 
Phase 3 trials have illustrated the benefits of briakinumab (in Phase 3 clinical 
development) and ustekinumab (approved in the EU, and also in other territories 
worldwide) in the treatment of moderate to severe plaque psoriasis. Available 
data indicate that a strategy targeting the IL-12 p40 subunit has considerable 
advantages over targeting of tumour necrosis factor-α, offering rapid onset of 
efficacy with a favourable dosing regimen (every 12 weeks for ustekinumab). 
Registries incorporating rigorous pharmacovigilance are now required to further 
understand the clinical profile of these drugs over long-term use.