Psoriasis: a Therapeutic approach

• In deciding which therapy to use, many factors must be taken into consideration, including safety, efficacy, availability, and cost. Long-term side effects will, of course, become better known as experience with each therapy grows. In particular, biologic medications are already in their second decade of use in rheumatology, but there is much less experience than with more traditional therapies. Comparisons of efficacy between therapies are hampered by the lack of quality comparative clinical trials. Clinicians are left with comparing studies which, for the most part, differ in patient population, data collection, and statistical methods. Availability of specific therapies differs depending on location: phototherapy requires ultraviolet light units and infliximab infusions require access to an infusion clinic. Availability of biologic therapies in particular is influenced by their relatively high cost and resulting difficulties with insurance coverage.

• Given the above limitations, the authors approach patients with psoriasis who require systemic therapy by performing a complete history and cutaneous examination. If there are no contraindications we generally start with NB-UVB with or without acitretin. If phototherapy is not an option due to logistical issues, methotrexate is usually started. For many patients these conventional treatments are very effective. If there is not an adequate response after approximately 12 weeks then patients may be switched to the alternative therapy or switched to a biologic medication. Occasionally PUVA is considered for patients with extremely thick plaques or patients with type V or VI skin. Cyclosporine is usually reserved for short-term treatment of flares, followed by transitioning to other therapies for  long-term control.

• In choosing a biologic medication, several situations may point to the use of one over another:

1. Etanercept is the most used biologic medication for psoriasis, in part because dermatologists have the most accumulated experience with it.
2. Obese patients may experience better efficacy with medications dosed using weight-based calculations with infliximab or ustekinumab.
3. Infliximab is one of the most efficacious therapies for psoriasis and in addition works very quickly. This may be the best treatment for patients with extremely severe psoriasis and in patients where hospitalization is a consideration.
4. Adalimumab and ustekinumab have also shown impressive results.

• As discussed above, some longer-term trials have shown some loss of efficacy when using biologic medications. It may then become necessary to switch those patients to a different biologic medication. There are two different options: changing to a medication in the same class (i.e. from a TNF inhibitor to another TNF inhibitor), or changing to a medication in a different class (i.e. from a TNF inhibitor to an IL 12/23 blocker such as ustekinumab). There is no strong evidence in the literature to differentiate between these two options at this time. Data exists in the rheumatologic literature showing efficacy when switching between TNF-inhibiting agents. There is also anecdotal evidence of efficacy when switching from a TNFinhibiting agent to a medication with a different mechanism of action or vice-versa.

Source of Information: Kalb. R 2013 (07) – Kalb. R. Treatment of Psoriasis in the Age of Biologics – 25th Annual Scientific Meeting of the Dermatological Society of Singapore (DSS) – Singapore