Biotech firm Genentech Inc, recently acquired by Roche Holdings AG for $47 billion, said Wednesday that it has pulled its psoriasis drug Raptiva from the U.S. market because of its association with rare, but often fatal brain infection.

The withdrawal is based on Raptiva’s association with progressive multifocal leukoencephalopathy, a viral disease that attacks the brain. It made the decision to pull the drug in conjunction with the U.S. Food and Drug Administration.

Genentech said, effective June 8, Raptiva will be no longer available and no new prescriptions should be issued. The company said the drug is being used by about 2,000 patients in U.S. and that people who have taken the drug is 46,000 worldwide since 2003.

Our decision to remove Raptiva from the market reflects Genentech's commitment to patient safety, Hal Barron, Genentech's senior vice president, development and chief medical officer, said in a statement. Although we believe that many psoriasis patients are benefiting from Raptiva, the balance between benefit and risk in the psoriasis population for which Raptiva was approved has significantly changed.

Earnings per share for Roche Holdings won't be affected by the decision, the company said. However it will take a $125 million charge for supplies of the medicine made but not sold, Roche said.

Raptiva reached $108 million in sales in 2008 out of Genentech's total of $13.42 billion.