Merck also said on Wednesday it planned to withdraw cladribine from markets in Australia and Russia where it has been approved and is available under the name Movectro.

“Merck believes that data from ongoing clinical trials are very unlikely to address the (U.S. Food and Drug Administration’s) requirements,” it said, adding new trials would not justify the costs.

A randomized, placebo-controlled trial called REFLEX showed that 62% and 76% of patients assigned to 44 mcg of interferon subcutaneously three times or once weekly, respectively, met 2005 McDonald criteria for MS after two years – the study’s primary endpoint – compared with 86% of patients treated with placebo, said Mark Freedman, MD, of the University of Ottawa.

The differences between the two interferon dosing schedules, and between the interferon schedules and placebo, were all statistically significant (P<0.01), he told attendees at the annual meeting of the Consortium of Multiple Sclerosis Centers (CMSC).

Among patients receiving MS diagnoses after 2005, records of nearly 30% indicated that they had reported fatigue to their physicians beforehand, said Joseph Berger, MD, of the University of Kentucky in Lexington, in a presentation at the annual meeting of the Consortium of Multiple Sclerosis Centers.

Berger noted that fatigue is a common symptom of MS, reported by many patients to be their biggest problem with the disease. Numerous previous studies have examined risk factors for fatigue and its relationship to disease progression following diagnosis.

Researchers hope one day to use stem cells in ways that cure spinal cord injuries, Parkinson’s disease and other ailments.

Stem cells are cells with the capacity to turn into any other type of human cell, be it bone, muscle or nerve cell.

The chemical known as granulocyte-macrophage colony-stimulating factor is an immune system which is part of the body’s defense against the disease.

According to two studies done by scientists from the University of Zurich and those from Thomas Jefferson University in Philadelphia, eliminating excess GM-CSF could help counter the deteriorating effects of MS and further relapses.

The potentially fatal infection, known as progressive multiform leukoencephalopathy (PML), occurs in an estimated 1.5 per 1,000 patients treated with Tysabri during months 25 to 36, the Food and Drug Administration said.

The FDA said it was the first time it had estimated the chances of PML for specific time intervals rather than providing a cumulative risk over years.

The data, which was presented at the 63rd Annual Meeting of the American Academy of Neurology, also showed that 72% of patients treated with Lemtrada were relapse-free compared to 41% for Rebif.

Lemtrada’s US application has been fast-tracked by the FDA and Genzyme expects to file for US and European approvals in early 2012.

The 23% lower annual relapse rate among the laquinimod patients versus the placebo ones is “statistically significant”, the researchers said. There was also a 36% reduction in disability progression as measured by Expanded Disability Status Scale, and 33% less brain atrophy among the laquinimod participants.

The drug, BG-12, also met the secondary goals of the study, according to Biogen, which sells the multiple sclerosis treatments Tysabri and Avonex.

In the study of more than 1,200 patients, BG-12 administered either twice or three times a day showed a highly statistically significant reduction in the number of patients who relapsed at two years compared with placebo.

The European Commission cleared the treatment for use against the relapsing-remitting form of multiple sclerosis, Basel, Switzerland-based Novartis said in a statement today. Doctors can prescribe the drug as the second choice of treatment for patients with an active form of the disease who’ve used beta interferon, or as the first drug for those with a rapidly evolving form of the disease.

Novartis Pharmaceuticals Canada Inc. announced last week it has received Health Canada approval to market fingolimod, sold under the brand name Gilenya, to treat the relapsing-remitting form of multiple sclerosis, the most common type found in adults.

In a so-called complete response letter, the U.S. drug regulator asked the German conglomerate to either provide additional analyses of study results that it had already submitted, or carry out new trials.

The European Medicines Agency (EMEA) earlier rejected Cladribine.

“People who have MS often leave the workforce before their motor symptoms emerge, and the reason they’ll often give is fatigue,” said Leavitt. “But it’s possible that it may be related to these changes in cognition, which are requiring them to use their brains in a different way.”

“People who have MS often leave the workforce before their motor symptoms emerge, and the reason they’ll often give is fatigue,” said Leavitt. “But it’s possible that it may be related to these changes in cognition, which are requiring them to use their brains in a different way.”