Biogen Idec and Elan Pharmaceuticals
- Administered via intravenous infusion every four weeks. Dose is 300 mg.
- Approved for individuals with relapsing types of MS. This drug is generally recommended for patients who have not responded adequately, or who cannot tolerate, another treatment for MS.
- At 18 months and up to 24 months of treatment with Tysabri, 87 percent of RRMS patients previously treated with other disease-modifying therapies showed stable or improved MRI scans. In this same group, disability scores as measured by EDSS were stable or improved in 59 percent of patients.
- This laboratory-produced monoclonal antibody acts against a molecule involved in the activation and function of lymphocytes and their migration into the central nervous system (CNS). Recent data suggest that it may also enhance myelination and stabilize damage to the myelin sheath. Preliminary results suggest that the drug may actually produce an improvement in function.
- Recent studies indicate that the drug increases the cumulative probability of achieving a sustained improvement in disability in RRMS, and substantially reduced clinical and MRI activity after breakthrough disease on other therapies. It also appears to have a positive effect on self-reported quality of life, to reduce fatigue, and to improve language processing.
- Following a suspension of the drug after two patients developed Progressive Multifocal Leukoencephalopathy (PML), an often-fatal viral infection of the brain, Tysabri was re-released. All patients now receive the drug through safety monitoring programs such as the Tysabri Outreach: Unified Commitment to Health (TOUCH™) Prescribing Program with registered infusion centers and pharmacies; and the international Tysabri Global Observation Program in Safety (TYGRUS). More than 55 cases of PML have now been reported. Studies are ongoing to see if it is possible to predict which individuals may be at risk for this condition, such as an antibody test for the virus that causes PML. In MS patients, no cases of PML have occurred prior to 12 months of continuous use.
- The drug shows continued effectiveness (as measured by a reduction in relapses), favorable MRI data, and a reduction in progression of disability (as indicated by an improvement in EDSS). It also shows promise as a therapy in patients who had a previously poor response to other disease-modifying therapies. It significantly improves the patients' perception of health-related quality of life, reduces MS-associated pain, has at least a mild positive effect on fatigue and depression, improves cognitive function, and may reduce loss of vision associated with RRMS.
- The Phase III SURPASS trial is evaluating 1,800 individuals with RRMS who have been treated earlier with either Rebif or Copaxone, and are then switched to Tysabri after continuing to experience relapses. The study began in February 2010 and is scheduled for completion in May 2013. The primary outcome measure is the annualized relapse rate; secondary measures include changes in T2-lesion volume, the proportion of subjects free from disease activity, and the change in patient-perceived physical status.
- The multinational STRATA study is evaluating efficacy and safety. It involves patients who participated in the earlier AFFIRM, SENTINEL, and GLANCE studies. The risk of PML appeared to increase with continued exposure to Tysabri.
- In addition to the risk of PML, side effects with Tysabri include liver damage, a three-fold increased incidence of Herpes zoster infections, occasional infections of a variety of types, and rare instances of anemia that are easily treatable. Individuals taking Tysabri are closely monitored by their healthcare team to watch for adverse events and provide immediate treatment if needed.