Risk of Progressive Multifocal Leukoencephalopathy (PML) with Use of Natalizumab
The U.S. Food and Drug Administration (FDA) is alerting the public that the risk of developing progressive multifocal leukoencephalopathy (PML), a rare but serious brain infection associated with the use of Tysabri (natalizumab), increases with the number of Tysabri infusions received. This new safety information, based on reports of 31 confirmed cases of PML received by the FDA as of January 21, 2010, will now be included in the Tysabri drug label and patient Medication Guide (see Data Summary for additional information).
Tysabri was approved by the FDA in November 2004 for the treatment of relapsing forms of multiple sclerosis (MS). Tysabri is also approved by FDA for treating moderately to severely active Crohn's disease.
Since 2006, Tysabri has only been available through a risk minimization plan called Tysabri Outreach Unified Commitment to Health (the TOUCH™ Prescribing Program). The program, developed by the FDA and the manufacturer of Tysabri, Biogen-Idec, is intended to make sure that healthcare professionals and patients understand the benefits and potential risks associated with the use of Tysabri, including the risk of PML.Under the TOUCH™ program, every patient who receives Tysabri is closely monitored for the occurrence of PML and other serious opportunistic infections. For additional information about the TOUCH™ program click here1.
Based on the available information, the FDA believes that the clinical benefits of Tysabri continue to outweigh the potential risks. Revisions to the drug label and patient Medication Guide, with the continued use of the TOUCH Prescribing Program, are intended to maximize the safe use of Tysabri and the identification of new PML cases.
The FDA continues to receive reports of PML in patients receiving Tysabri in the United States and overseas. Tysabri, an immunosuppressant medication, was first approved by the FDA in November 2004 for the treatment of relapsing forms of multiple sclerosis (MS). In February 2005, the marketing of Tysabri was suspended by the manufacturer after three patients in clinical trials (two patients in MS trials and one in a Crohn's disease [CD] trial) developed PML. In June 2006, the FDA approved an application for the re-marketing of Tysabri as monotherapy for the treatment of patients with relapsing forms of MS.
Tysabri is generally recommended for patients who have had an inadequate response to, or are unable to tolerate, an alternate MS therapy. In January 2008, Tysabri was also approved for inducing and maintaining a clinical response and remission in patients with moderately to severely active CD who have had an inadequate response to, or are unable to tolerate, conventional CD therapies.
Since July 2006 (when marketing resumed) through January 21, 2010, there have been 31 confirmed cases of PML worldwide in patients using Tysabri. Of these 31 case reports, 10 were from patients in the U.S. As of January 21, 2010, eight patients have died. In all cases, patients were receiving Tysabri as monotherapy for the treatment of MS. There have been no postmarketing reports of PML in patients treated with Tysabri for CD. In the U.S., less than 2% of Tysabri use is in patients with CD. Tysabri is not approved for CD outside of the U.S.
The risk of developing PML increases with the number of Tysabri infusions received. Tysabri is administered as a single intravenous infusion every four weeks. The overall worldwide cumulative rate of PML in patients who have received one or more Tysabri infusions is 0.5 cases of PML per 1,000 patients. Since Tysabri's re-marketing in the U.S., there have been no cases of PML in patients treated with Tysabri for less than 12 months. The overall worldwide cumulative rate of PML in patients who have received at least 24 infusions is 1.3 cases of PML per 1,000 patients. In the U.S., the cumulative rate of PML in patients who have received at least 24 infusions is 0.8 per 1,000 patients. Outside of the U.S., the cumulative rate of PML in patients who have received at least 24 infusions is 1.9 per 1,000 patients.
Approximately 66,000 people, worldwide, have received at least one dose of Tysabri since marketing resumption (through December 31, 2009). Relatively few patients have received 36 infusions or more, either in clinical trials or since marketing resumption; therefore, the magnitude of the risk of PML and other adverse events in patients who have received 36 infusions or more is not able to be well characterized.
The following table summarizes cumulative rates of PML according to geographic location and number of Tysabri infusions received since Tysabri re-marketing:
The FDA and its international counterparts remain committed to tracking and monitoring for any change in the risk of PML associated with the use of Tysabri.
This communication is intended to increase awareness about the risk of PML in patients treated with Tysabri.At this time, the FDA believes that the clinical benefits of Tysabri outweigh its risks. Tysabri will remain available to patients through the TOUCH™ Prescribing Program. Under this program, every patient who receives Tysabri is closely monitored for the occurrence of PML and other serious opportunistic infections.