Natalizumab for treatment of active Crohn's disease

Crohn's disease is a chronic inflammatory disease of the intestines. Crohn's disease frequently occurs in the lower part of the small intestine, called the ileum, but it can affect any part of the digestive tract, from the mouth to the anus. The most common symptoms of Crohn's disease are abdominal pain, often in the lower right area, and diarrhea. Natalizumab blocks the adhesion and migration of white blood cells into the gut reducing chronic inflammation associated with Crohn's disease. Four high quality studies were reviewed. The studies tested 1692 people over the age of eighteen who had moderate to severe Crohn's disease. The subjects received 1 to 3 infusions of natalizumab (at a dosage of 300 mg or weight based dosages of 3, 4 or 6 mg/kg) or placebo (fake infusions). The studies lasted for 12 weeks. The results of the studies indicate that natalizumab is effective therapy for some people with active Crohn's disease. People with active disease responded positively to even one treatment of the drug and the studies examined showed increased benefits with additional injections of natalizumab. More people improved through treatment using natalizumab than those using the fake treatments. The drug was generally well tolerated and side effects occurred infrequently. Serious side effects occurred rarely (range 7 to 11% for natalizumab and placebo patients). Few patients withdrew from the studies due to side effects (2 to 8% for natalizumab compared to 3 to 7% for placebo). Side effects that occurred during the trials included: headache, worsening of Crohn's disease, abdominal pain, arthralgia, colitis, influenza syndrome, infection, nausea, vomiting, fatigue, hypersensitivity-like reactions, and the development of antibodies against natalizumab. Recently, it was found that two patients who received natalizumab in combination with interferon beta-1 for multiple sclerosis and one patient who received natalizumab in combination with azathioprine for Crohn's disease developed a severe disease called progressive multifocal leukoencephalopathy (PML) resulting in two deaths. PML is a serious infection of the nervous system. However an investigation of more than 3500 patients who took natalizumab found no new cases of PML. It was discovered that PML is not always fatal and regular testing of patients could provide adequate safety and ensure the well-being of those taking natalizumab. However, the benefits of natalizumab for people with Crohn's disease should be carefully weighed against the potential risk of serious adverse events such as the possibility of infection of the nervous system.