News

MAKERS OF TYSABRI WITHDRAW MS DRUG FROM MARKET AND TRIALS

LINKED TO RARE, OFTEN FATAL BRAIN INFECTION

Tysabri, the multiple sclerosis drug released to the public with great expectations in November 2004, continues to raise concerns after its withdrawal from the market due to its possible involvement in cases of a rare and often fatal brain infection. A fifth case of the brain disease with possible ties to the drug has been reported to federal authorities as of June 2005.

Three cases of the disease, known as progressive multifocal leukoencephalopathy or PML, have been confirmed in patients on a long-term course of Tysabri. The patients were continuing on the drug after participation in clinical trials of the drug prior to its release to the public. Of these three, two have died. Two additional cases of PML in MS patients taking Tysabri, including this most recent one, have not yet been officially confirmed.

The drug's manufacturers, Biologen Idec Inc. and Elan Corp, plc voluntarily withdrew Tysabri from the market and halted any further clinical trials after the second fatality linked to the drug was reported. They are currently working with the FDA to determine the exact nature of the link between their drug and the disease, and if there is a way to use the drug without risk of the dangerous side-effect.

PML is a rare disease of the central nervous system, caused by a common virus known as JC which usually stays dormant in the body. It only becomes active and causes illness when a patient's immune system function is severely depressed, either due to other diseases (such as AIDS), or other medications (such as drugs used for cancer chemotherapy). The disease sets in quickly, causing mental deterioration, vision loss, speech disturbances, loss of coordination, paralysis, and ultimately coma and usually death. There is no cure or effective treatment for PML.

Both the manufacturers of Tysabri and organizations representing MS patients remain hopeful that Tysabri can eventually be brought back to market once the reason for this dangerous side-effect has been determined and corrected. There are currently no cures for MS, and only five other drug therapies have been approved for slowing its symptoms. Tysabri represented a new direction in MS treatment, as it is a member of a new family of drugs known as monoclonal antibodies, a family which still holds out great promise for effective MS treatment.

SUN EXPOSURE ASSOCIATION WITH MS

Scientists at the University of Tasmania report new evidence that increased sun exposure between the ages of 6 to 15 is associated with decreased risk of multiple sclerosis (MS), a debilitating autoimmune disease.

The finding may help explain the reason for greater incidence of multiple sclerosis in places with higher latitudes. Conversely, incidence of MS is lower in tropical locations closer to the equator receiving more direct sunlight. The research results bolster the hypothesis that environmental factors may be at least partially responsible for development of the disease.

Results from laboratory experiments reveal mice induced to develop experimental autoimmune encephalomyelitis (EAE), the animal model of MS, avert the disease process when exposed to UV radiation or injected with the active form of vitamin D. UV radiation emitted by the sun triggers vitamin D synthesis in the skin. The University of Tasmania research team wanted to examine whether UV radiation had the same protective effect against MS in humans.

Scientists chose inhabitants from the island state of Tasmania for the study. Tasmania has a high prevalence of multiple sclerosis with nearly 76 out of every 100,000 people afflicted with the disease. The study included 136 participants with multiple sclerosis and 272 controls without the disease.

Scientists used a questionnaire to determine past sun exposure, protective measures against the sun, use of vitamin D supplements, medical history and other factors potentially associated with multiple sclerosis. Researchers assessed skin phenotype and measured skin damage to obtain objective markers of cumulative lifetime sun exposure.

The results indicate that higher levels of sun exposure during childhood and early adolescence and skin damage correlate with reduced risk of multiple sclerosis. Lack of sufficient UV radiation and insufficient vitamin D may be involved in development of the disease.

References:
British Medical Journal (2003;327:316)

GENETIC BASIS FOR MS?

A study of 370 sets of Canadian twins bolsters evidence of an underlying genetic basis for multiple sclerosis (MS), a disabling neurological disease in which the immune system attacks the central nervous system.

Diseases may be caused by a combination of factors including genetics, diet, exercise and exposure to environmental pollutants. Twin studies involving subjects with similar or identical gene arrangements afford scientists the opportunity to determine the extent to which genetics contribute to disease.

Research compiled over two decades from the Canadian twin study concludes that identical twins exhibit a 25% overall risk of developing MS when the other twin has the disease. The rate is higher in identical twin females who have a 34% chance of acquiring MS when their twin sister has the disease. As is the case with many autoimmune diseases, most people with MS are women. Two out of every three people with the disease are female. The risk drops to 5.0% for male identical twins and 5.4% for fraternal (non-identical) twins.

In addition to confirming the genetic susceptibility underlying MS, scientists concur that a person must be exposed to an appropriate trigger to initiate the disease. The list of suspected non-hereditary triggers includes viruses, lack of sufficient sunlight and exposure to environmental toxins. Identification of both the genetic and non-hereditary factors involved in the disease will enable scientists to devise targeted treatments for MS.

Drs. CJ. Willer and George C. Ebers published the study involving scientists from the Wellcome Academy of Sciences for Human Genetics (United Kingdom), Stanford University, the University of British Columbia and the Canadian Collaborative Study Group. The results appear in the September 29, 2003 Early Edition issue of the Proceedings of the National Academy of Sciences.

References:
PNAS (Early Edition online September 29, 2003

MS PATIENTS REPORT BENEFIT FROM COMPLEMENTARY AND ALTERNATIVE MEDICINE (CAM)

A new study concludes the majority of MS patients who use complementary and alternative medicine (CAM) for treatment of the disease report benefits from the therapies.

Complementary and alternative medicine (CAM) encompasses a broad range of disciplines outside the realm of Western medicine. Herbal supplements, acupuncture, massage therapy, chiropractic and meditation represent examples of CAM. While few controlled studies exist to prove the safety and efficacy of CAM, consumers are flocking to alternative practitioners in greater numbers than ever before. Studies in Canada reveal approximately 50% of the population reported using CAM in 1999, an increase from 20-22% in the early 1990s.

The study includes nearly 700 subjects from the Calgary MS Clinic database. The average age of participants was 48 years old. The majority (75%) of respondents were female. Eighty five percent of participants reported suffering moderate to severe disability from symptoms associated with MS. Patients reported pursuing alternative treatments to improve health (68%) and to treat MS symptoms (61%). Sixty percent of respondents took conventional medications for management of MS symptoms. Seventy percent of the respondents in the study reported using CAM within the last two years. The overwhelming majority (72%) reported positive effects from CAM treatments. Patients regarded massage therapy and acupuncture as particularly beneficial.

CAM users obtained information about alternative treatments most frequently from the media (50%) and from family and friends (50%). MS patients cited lack of knowledge of CAM (42%) as the single greatest reason for not utilizing these treatments. The majority of MS patients undergoing alternative treatments informed their primary care practitioners and neurologists of their CAM use.

Results from controlled studies could substantiate anecdotal evidence from MS patients who report perceived benefits from CAM in the treatment of MS symptoms. In the meantime, a majority of MS patients regard CAM a valuable adjunct to conventional management of their disease.

References:
Chronic Dis Can. 2003 Spring-Summer;24(2-3):75-9.