TYSABRI: "Biologic treatment for MS offers hope": Daytona Beach News-Journal

December 18, 2006

Biologic treatment for MS offers hope
By DR. YONG H. TSAI

Susan awoke one day with blurred, obstructed vision along with dizziness and numbness in her legs. A trip to her doctor's office triggered an order for blood tests and an MRI. She was diagnosed with multiple sclerosis (MS), an autoimmune disease involving the central nervous system.

Our brain and spinal cord, that house the main pathway of our body's nerve signals, offer a layer of insulation, called myelin, that surrounds and protects these nerve cells.

Like a plastic cover that surrounds the many wires of an electric cable, myelin covers nerve fibers to ensure that the nerve signals have safe, uninterrupted passage.

With MS, myelin sheaths break down (demyelination), due to inflammation caused by the autoimmune process. Damaged tissue eventually turns into scar tissue (sclerosis), meaning "multiple sclerosis."

Classic symptoms of MS include numbness, visual disturbance, abnormal gait, imbalance, muscle weakness or spasm, urinary incontinence, vertigo, slurred speech and even pain.

There are several forms of MS. Relapsing-remitting MS (RRMS) occurs about 25 percent of the time with intermittent relapses, including worsening of existing symptoms or the development of new ones.

Over the course of 10 to 15 years, more than 50 percent of RRMS will evolve into progressive MS, known for more frequent relapses, incomplete remission bouts and general overall deterioration.

During the past few years, beta interferons such as Avonex, Rebif, Betaseron and Glatiramer acetate, by modifying the inflammatory process, have been used to treat MS.

However, all still have side effects and some have poor results. In November 2005, Natalizumab (Tysabri), a biologic agent, was proven to block the function of key molecules. The process could transport immune cells crossing the brain and blood barrier (BBB), and prevent against an attack on one's central nervous system.

Clinical trials have shown Tysabri, administered by monthly intravenous infusion, is a very effective therapy in reducing relapses and decreasing new brain lesions.

However, the shocking news surfaced Feb. 28 that Tysabri was suspended temporarily from commercial distribution due to three serious, adverse events. Multifocal leukoencephalopathy (PML) occurred in clinical trial patients treated with Tysabri plus Avonex.

However, there have been no reports of PML in patients treated with either Tysabri or Avonex alone.

More recently, Tysabri has been permitted for MS treatment. Tysabri is only indicated as a single-agent treatment instead of in combined therapy with Avonex or other agents. It's for patients with the relapsing form of MS and poor response to traditional treatments.

Though there is some concern with rare side effects of Tysabri, this new biologic agent offers new hope.