An overview of biotherapies in psoriasis.

The TNF-α (Tumour Necrosis Factor-α), is a cytokine with proven anti-inflammatory properties. It is found in the body under normal conditions. During psoriasis, its activity abnormally increases. As a result, psoriasis is caused by the increased activity of TNF-α. To halt the progression of the disease, an antibody is introduced into the body. It blocks the action of TNF-α and thus alleviates the symptoms of psoriasis. Four anti-TNF-α have been developed: etanercept, adalimumab, and infliximab.

Besides TNF-α, IL-23 and IL-17 are also inflammation molecules targeted by monoclonal antibodies in biotherapies. The molecules introduced in biotherapies are proteins. Their administration is done through subcutaneous or intramuscular injection. By lowering the levels of molecules causing skin and joint inflammation, biotherapies reduce the activity of psoriasis. Three treatments specifically targeting IL-23 have been developed: guselkumab, tildrakizumab, risankizumab, as well as three treatments targeting IL-17: secukinumab, ixekizumab and brodalumab.

Biologic therapy reduces the symptoms of psoriasis, without, however, completely eliminating them. To optimise the results, it must be continued for many years.

Biotherapies are not without risks and side effects. Due to their mechanism of action, each molecule used has a profile of adverse effects. By blocking an element involved in immune defence, they risk exacerbating infections. Therefore, before starting a biotherapy, it is prudent to screen for the presence of latent tuberculosis so as not to reactivate it.

Indeed, tuberculosis is a disease caused by a bacterial infection, known as Mycobacterium tuberculosis. In its latent form, the bacteria can remain in the body without causing any symptoms. However, when the immune system is weakened, the body's ability to control the infection decreases, allowing the bacteria to reactivate and cause active tuberculosis.

Furthermore, it is recommended to get vaccinated against influenza and pneumococcus, as these infections can prove to be more severe and lead to serious complications in individuals whose immune system is weakened, particularly by biotherapies. Vaccination against influenza and pneumococcus thus reduces the risk of contracting these infections and can help to prevent associated complications. During the course of treatment, it is necessary to consult a doctor in case of fever to avoid the worsening of an infection.

The oral administration of biotherapy molecules is prohibited. Indeed, this leads to the destruction of the molecules in the digestive tract. Furthermore, they can easily denature, particularly under extreme temperatures. As a result, they must be stored in a cool place. In addition, biotherapy is contraindicated for pregnant and breastfeeding women, as well as in cases of allergic sensitivity. Indeed, biotherapies cross the placental barrier and may pose a risk of immunosuppression in the newborn.