In the maintenance study that enrolled responders to natalizumab to placebo or natalizumab, response rates at 9 and 15 months were 61% and 54%, respectively, among those who continued on natalizumab vs. 28% and 20%, among those on placebo, significant differences.
No PML cases were identified in the studies. Adverse events included hypersensitivity reactions, at a rate of 3.5%. The malignancy rate was slightly higher for natalizumab vs. placebo (0.6% vs. 0.2%). Infections were slightly more common, including upper respiratory tract infections and herpes simplex infections, in natalizumab-treated patients. There were two cases of viral meningitis and one case of cytomegalovirus colitis, but none in placebo-treated patients in the 3-month trials.
The company has proposed a version of the TOUCH prescribing program adapted for Crohn disease patients, called “CD-TOUCH,” with the same goals but with modifications to accommodate differences in the treatment and management of patients with CD. One difference is the recommendation to stop treatment in patients who have had no response in 3 months and to eliminate corticosteroid use within 6 months of starting treatment.
As of July 2007, more than 8,600 patients had received treatment with natalizumab commercially, and more than 4,300 patients were receiving the drug in the European Union. In July, Elan and Biogen Idec announced that they were appealing a European Medicines Agency decision against approving natalizumab for patients with Crohn disease.