Click "Read More" to see comments from the US FDA, Elan, Biogen, the investment community, and competitors (the most fun part!)...

From the United States Food and Drug Administration (the approval agency for new drugs):

"This innovative treatment for multiple sclerosis represents a new approach to treating MS -- exciting news for patients with this serious disease," Dr. Lester M. Crawford, acting FDA commissioner, said in a statement. "While we eagerly await long-term results from ongoing clinical trials, we have reason to believe that Tysabri will significantly reduce relapses in MS."

From Biogen, the co-sponsor of Tysabri::

"TYSABRI is a powerful and innovative therapy that offers new hope for hundreds of thousands of people living with MS," said James C. Mullen, chief executive officer, Biogen Idec. "We believe TYSABRI will revolutionize the treatment of MS and become the leading choice for patients and physicians."

From Elan, the co-sponsor of Tysabri:

"TYSABRI is a significant breakthrough for patients with MS," said Kelly Martin, president and chief executive officer, Elan. "The approval of TYSABRI, with its unique mechanism of action and new level of efficacy, has the potential to make a genuine difference in the lives of patients and families who struggle with the debilitating effects of this disease."

From the director of one of the Tysabri trials:

"I believe TYSABRI will be an important therapeutic advance for patients with relapsing MS," said Richard Rudick, MD, lead investigator of the SENTINEL trial and director, Mellen Center for Multiple Sclerosis, Cleveland Clinic Foundation. "Patients who have discontinued therapy, are newly diagnosed with MS, or have persistent active disease despite being on a current therapy will benefit from TYSABRI."

From the Investment Analysts:

"We believe Tysabri's efficacy profile will likely drive its widespread adoption in first- and second-line MS therapy," [CIBC WorldMarkets] analyst Bret Holley told clients in a note. "We expect physician and patient enthusiasm for the drug will be very high."

"The approval is very good news," said Morgan Stanley analyst Marc Goodman, who expects Tysabri to achieve peak sales of $2.5 billion. "We expect this drug to be a paradigm shift in MS therapy as we believe its therapeutic profile is so much better than existing therapy."

From the Competition:

Ernesto Bertarelli, chief executive of Serono (SRA: news, chart, profile), which makes the MS drug Rebif, said full knowledge of the drug's effectiveness won't be known until after two years of study. Only one year has been completed thus far, he said. "This is good news for patients, but we need more data," he said. "We have long-term therapy that does the same thing."

From the National Multiple Sclerosis Society:

"The MS community is pleased that the FDA approval of TYSABRI provides an additional treatment option for people with relapsing forms of MS. There are many people living with MS who may benefit from this different treatment approach," said Stephen C. Reingold, PhD, vice president for research, the National MS Society.