Psoriasis is a chronic autoimmune condition primarily affecting the skin, characterized by patches of abnormal skin that can be red, itchy, and scaly. This condition develops when the immune system mistakenly attacks healthy skin cells, leading to their rapid overproduction. Biologics represent a modern and targeted treatment approach for individuals with moderate to severe psoriasis. These therapies offer a more precise way to manage the underlying immune processes driving the disease, aiming to reduce symptoms and improve overall well-being.
Understanding Psoriasis Biologics
Biologics are a class of medications derived from living cells, genetically engineered to target specific components of the immune system. Unlike older systemic treatments that broadly suppress the immune system, biologics are designed to interfere with precise inflammatory pathways involved in psoriasis. In psoriasis, an overactive immune system leads to an excess of certain proteins called cytokines, which drive inflammation and the rapid growth of skin cells. For example, they can target and neutralize certain cytokines or block the activity of specific immune cells, such as T-cells, that play a role in the inflammatory process. This targeted action helps to quiet the overactive part of the immune system responsible for psoriasis, leading to symptom improvement while potentially minimizing broader immune suppression.
Classes of Biologic Therapies
Several classes of biologics are used to treat psoriasis, each targeting a distinct part of the immune system’s inflammatory cascade.
Tumor Necrosis Factor-Alpha (TNF-alpha) Inhibitors
This class includes medications like adalimumab, etanercept, infliximab, and certolizumab pegol. These drugs work by blocking the activity of TNF-alpha, a pro-inflammatory cytokine that plays a role in stimulating keratinocyte proliferation and facilitating inflammatory cell entry into the skin. By binding to TNF-alpha, these biologics prevent it from interacting with its receptors, thereby reducing inflammation.
Interleukin-17 (IL-17) Inhibitors
This class includes secukinumab, ixekumab, and brodalumab. These biologics specifically target interleukin-17A or its receptor, a cytokine that significantly contributes to the inflammation and excessive skin cell growth seen in psoriasis. By blocking IL-17A, these inhibitors disrupt the inflammatory pathway, which helps to improve psoriasis symptoms.
Interleukin-23 (IL-23) Inhibitors
This class includes ustekinumab, guselkumab, risankizumab, and tildrakizumab. These medications work by preventing IL-23 from binding to its receptor, which in turn inhibits the activation of T-helper 17 (Th17) cells. Th17 cells are responsible for producing IL-17, so by blocking IL-23 upstream, these drugs indirectly reduce IL-17-driven inflammation. This helps reduce inflammation and skin cell proliferation.
Treatment Administration and Expected Outcomes
Biologic treatments for psoriasis are typically administered either through subcutaneous injections or intravenous infusions. Subcutaneous injections are given under the skin and can often be self-administered at home after proper training from a healthcare professional. Intravenous infusions, on the other hand, are given directly into a vein, usually in a clinic or hospital setting, and require administration by a healthcare provider. The frequency of these doses varies depending on the specific biologic, ranging from weekly or bi-weekly injections to monthly or even quarterly infusions. For instance, some IL-17 and IL-23 inhibitors might be given every 4, 8, or 12 weeks, with some IL-23 inhibitors potentially allowing for extended intervals up to 16-24 weeks in stable patients.
Patients can anticipate significant improvements in their psoriasis symptoms with biologic therapy. This includes substantial skin clearance, a reduction in itching, and an overall enhancement in their quality of life. While some individuals may see clearer skin within a few weeks, the full benefits often take more time to become apparent, and results can vary among patients. Continuous use of the biologic tends to be more effective, and stopping and starting treatment can lead to a loss of effectiveness.
Because these medications modulate the immune system, there is an increased risk of infections. Patients should report any signs of infection, such as fever or flu-like symptoms, to their healthcare provider promptly. Other potential side effects include injection site reactions, and less common but serious risks such as the exacerbation of heart failure, neurological disorders, or certain cancers. Patients should discuss these potential risks and benefits with a healthcare provider before starting treatment.
Determining Eligibility for Biologics
Biologics are generally considered for patients with moderate to severe psoriasis, particularly when traditional systemic therapies have not been effective, are no longer tolerated, or are contraindicated. Traditional systemic treatments often include medications like methotrexate, cyclosporine, or phototherapy. The severity of psoriasis is often assessed by the percentage of the body covered by affected skin; moderate psoriasis typically involves 3% to 10% body surface area, while severe psoriasis affects more than 10%.
A comprehensive medical evaluation by a dermatologist is necessary to determine eligibility for biologic therapy. This evaluation considers the overall severity of the disease, the patient’s complete health history, and any co-existing medical conditions. Before initiating treatment, patients typically undergo medical tests, including blood tests and tuberculosis screening, due to the immune-modulating effects of biologics.