Crohn’s disease is a chronic inflammatory condition that affects the digestive tract, causing symptoms such as abdominal pain, diarrhea, and weight loss. While conventional treatments like aminosalicylates, corticosteroids, and immunomodulators can help manage the disease, some patients experience persistent inflammation or severe complications. For these individuals, a more targeted approach is often necessary to achieve and maintain remission. Biologic drugs represent a significant advancement in the treatment of Crohn’s disease, offering a focused way to address the underlying inflammatory processes.
What Are Biologic Drugs?
Biologic drugs are a class of medications derived from living organisms, such as cells, proteins, or antibodies, unlike chemically synthesized conventional drugs. They are engineered to specifically target components of the immune system that contribute to inflammation in conditions like Crohn’s disease. This targeted action helps interrupt the inflammatory cascade. By focusing on specific inflammatory pathways, biologics aim to reduce the inflammatory burden, leading to symptom improvement and disease remission.
How Biologics Target Crohn’s Disease
Biologics work by blocking specific proteins or pathways that drive the inflammatory process in Crohn’s disease. One prominent class is anti-tumor necrosis factor (TNF) agents, which neutralize TNF-alpha, a protein that plays a central role in inflammation. By binding to TNF-alpha, these drugs prevent it from signaling immune cells to perpetuate inflammation, leading to a reduction in symptoms and healing of the inflamed intestine.
Another class of biologics, anti-integrin agents, prevents immune cells from migrating into inflamed tissues. These drugs block specific adhesion molecules, such as alpha4 beta7 (α4β7) integrin, expressed on immune cells that bind to molecules on the surface of blood vessels in the gut. This action reduces the influx of inflammatory cells into the intestinal lining.
Anti-interleukin (IL)-12/23 agents represent a third mechanism, targeting interleukins 12 and 23. These cytokines are involved in activating specific immune pathways (Th1 and Th17) that contribute to inflammation in Crohn’s disease. By blocking the p40 subunit common to both IL-12 and IL-23, these biologics disrupt the signaling necessary for these pathways.
Common Biologic Medications for Crohn’s
Several biologic medications are prescribed for moderate to severe Crohn’s disease, each belonging to a specific drug class. Infliximab (Remicade) is an anti-TNF agent and was one of the first biologics approved for Crohn’s, often used for inducing and maintaining remission. Adalimumab (Humira) is another widely used anti-TNF biologic, administered subcutaneously.
Vedolizumab (Entyvio) is an anti-integrin agent that specifically targets the gut, preventing immune cells from entering the intestinal tissue. This drug is considered for patients who may not have responded to anti-TNF therapies. Ustekinumab (Stelara) is an anti-IL-12/23 agent that targets specific interleukins involved in inflammation. It is used for patients who have not responded to other biologics. Risankizumab (Skyrizi) is a newer selective anti-IL-23 antibody, approved for Crohn’s disease.
Receiving Biologic Treatment
Biologic treatments for Crohn’s disease are administered either through intravenous (IV) infusions or subcutaneous (under-the-skin) injections. IV infusions, such as infliximab, are given in a clinic or hospital setting every few weeks. Subcutaneous injections, like adalimumab or ustekinumab, can be self-administered at home after proper training, with frequencies ranging from every other week to every eight weeks.
Before starting biologic therapy, patients undergo screening for conditions like tuberculosis or hepatitis, as these drugs can affect the immune system. During treatment, ongoing monitoring is important, including regular follow-up appointments and laboratory tests, to assess effectiveness and watch for potential issues.
Common side effects can include injection site reactions, such as redness or pain, or mild infections like colds. While serious side effects, such as more significant infections or allergic reactions, are possible, they are less common. Patients should communicate any new or worsening symptoms to their healthcare provider. Adherence to the prescribed dosing schedule and consistent communication with the medical team are important for achieving the best possible outcomes.