Author: Vanessa Ngan, Staff Writer, 2003. Updated by Chief Editor: Hon Assoc Prof Amanda Oakley, Dermatologist, Hamilton, New Zealand, February 2015.
Biologics, also known as biologic therapies or biological response modifiers, are drugs derived from living material (human, plant, animal, or micro-organism). They interfere with specific parts of the body's immune system to treat and prevent immune-mediated inflammatory disorders and cancers. They are also called targeted therapies.
Biologics approved for the treatment of psoriasis include:
These medications are also used for other severe health problems. Registered indications in New Zealand in January 2018 are shown below.
Evidence strongly suggests that psoriasis is a disorder of the immune system. This basically means that an individual's immune system starts reacting against his or her own tissue. In this particular instance, abnormally large numbers of T cells (a type of white blood cell) trigger the release of cytokines (chemicals in the body's immune system) that can cause inflammation, redness, itching and flaky skin patches characteristic of psoriasis.
Biologics work by interfering with specific components of the autoimmune response. Unlike general immunosuppressants that suppress the entire immune system, biologics can fight more selectively and target only those chemicals involved in causing psoriasis.
Etanercept, infliximab and adalimumab belong to the class of biological medicines called tumour necrosis factor-alpha (TNFα) blockers. These work by blocking the activity of TNFα, the primary cytokine involved in psoriasis. Ustekinumab targets interleukin-12 (IL-12) and IL-23. Secukinumb, ixekinumab and brodalumab target IL-17.
All these biological medicines are given at defined intervals. The interval between doses is dependent on each individual biological medicine. Etanercept, alefacept and efalizumab are usually once weekly, and adalimumab is every two weeks by self-administered subcutaneous injection. Infliximab is given by intravenous infusion at a hospital or clinic, 3 times over a period of 6 weeks and then every 8 weeks.
In many cases, other topical and systemic medications for psoriasis (eg, methotrexate) may also be prescribed in an attempt to improve efficacy.
Biologic medication are often very effective in psoriasis. However, in some cases, they lose their effectiveness after a period of time (secondary failure) and other treatment may be required.
To date, biologics for psoriasis appear to have very few side effects. Because of their precise targets, they appear not to damage the entire immune system the way that general immunosuppressants do. However, biologics should still be considered immunosuppressive and may increase the risk of infection and reactivation of tuberculosis (TB). Uncommon infections with organisms such as listeria and legionella may be more common and more serious in patients on biologics.
Screening for latent TB should be undertaken prior to commencing a TNFα inhibitor and other biologics.
On the other hand, mortality may be reduced in patients taking TNFα inhibitors compared to that in patients with psoriasis that are not taking them. This is due to a marked reduction in myocardial infarction. Some of the newer biologics may also be associated with lower rates of malignancy than arise in matched patients that are not taking them.
Due to the high cost of these medicines, their use is limited to patients with moderate to severe psoriasis where:
In New Zealand, infliximab, adalimumab and etanercept are funded by PHARMAC for some cases of severe psoriasis on Special Authority application.
Immunisation status should be reviewed prior to starting biologic treatment. If necessary, vaccines should be updated prior to treatment. Annual influenza vaccination is recommended.
As they may induce illness in immunodeficient individuals, live vaccines should not be used during treatment with biologics. Currently available live attenuated viral vaccines include measles, mumps, rubella, varicella, yellow fever, influenza (intranasal vaccine) and oral polio vaccine. Live attenuated bacterial vaccines include BCG and oral typhoid vaccine.
It is recommended that patients on biologic medications should be monitored, and should have routine blood tests at least every 6 months or so, including full blood count and liver function tests. Screening for latent TB should be repeated from time to time.
Research and development in the field of biologics is very exciting. Drugs under development for treating psoriasis in 2015 include:
Other biologics used for severe skin diseases (January 2018) include:
There are many other promising biologics under investigation for skin conditions.
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