The MS drug that always seems to find itself in the news is making headlines again, but this time the message may be relatively positive. Natalizumab (Tysabri, Biogen Idec) does not appear to carry the level of risk of progressive multifocal leukoencephalopathy (PML) previously estimated—and the infections are less deadly—according to new postmarketing surveillance data. Previous research said that the risk of developing PML was 1 in 1,000, but new data show it's closer to 1.2 per 10,000 patients, according to Carmen Bozic, MD, vice president and global head of drug safety and risk management for Biogen Idec. Dr. Bozic delivered her remarks at the AAN's 61st Annual Meeting.

The new data were taken from the Tysabri Outreach: Unified Commitment to Health (TOUCH) prescribing program and the Tysabri Global Observation Program in Safety (TYGRIS), according to Medical News Today. TOUCH is a mandatory prescribing program that ensures proper and educated use of natalizumab. TYGRIS is a global voluntary observational study evaluating the long-term safety of natalizumab in clinical practice. About three years after approval in the US and the European Union, approximately 52,000 patients had been treated with natalizumab in the postmarketing setting, more than 10 times the exposure in clinical trials, according to Dr. Bozic.

There is now a plethora of information about long-term exposure in the postmarketing setting, she said. To date, just shy of 25,000 patients have been taking the drug for 12 months or longer, 14,400 for 18 months or longer, and 6,800 for 24 months or longer. Some patients have taken the drug for more than 2.5 years, she added. The six patients who developed PML—three men and three women ranging in age from 37 to 59 years—used the drug as monotherapy for periods ranging from 12 to 31 months, a highly variable duration of treatment, Dr. Bozic noted.

Biogen and Elan also announced results from an ongoing, one-year longitudinal health outcomes study (n=1275) in which patients who received three infusions of natalizumab reported reduced fatigue, as well significant improvements in general and disease-specific measurements of quality of life (QoL) and cognitive function. The 12-item Short Form Scale Physical Component Summary (baseline 34.03 vs. 36.02 at the 3rd infusion; p<0.001) and the SF-12 Mental Component Summary Score (baseline 43.17 vs. 47.22 at the 3rd infusion; p<0.001) showed statistically significant improvements from baseline.

For the 29-item Multiple Sclerosis Impact Scale, there were statistically significant improvements from baseline for both the physical (baseline 48.25 vs. 40.19; p<0.001) and psychological (baseline 43.70 vs. 34.80; p<0.001) impact scores.

FDA has given the green light to a high-titer production process for Biogen Idec's Tysabri, allowing the manufacturer to increase the production yield up to four-fold, according to a company statement. The high-titer production process has already been in place in Europe.