Updated from 5:43 p.m. EDT Genentech ( DNA) announced Wednesday it was voluntarily withdrawing its psoriasis drug Raptiva from the U.S. market.

Genentech, now a unit of drug maker Roche, says it based the decision on the association of Raptiva with an increased risk of progressive multifocal leukoencephalopathy (PML), a rare and usually fatal disease of the central nervous system.

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Genentech said that roughly 2,000 patients in the U.S. may currently be receiving Raptiva for chronic plaque psoriasis and that roughly 46,000 have been treated with the drug since it was approved in 2003. Berkeley, Calif.-based Xoma ( XOMA) receives royalties on Raptiva sales.

"Our decision to remove Raptiva from the market reflects Genentech's commitment to patient safety," said Hal Barron, Genentech's senior vice president, development and chief medical officer. "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."

Genentech said it does not believe the withdrawal will have a significant impact on the group's net income or earnings per share, though the company will be reporting a related one-time cost-of-sales charge of approximately $125 million. U.S. Raptiva sales for 2008 were roughly $108 million. Total sales for that period were $13.42 billion.

In February, health officials said that three patients taking Raptiva were believed to have died of PML. "We take the risk of PML very seriously and are working diligently with the FDA to put the right plans in place that will help protect patient safety," company spokeswoman Tara Cooper said at the time.

PML, symptoms of which include which include weakness, blurred vision and difficulty speaking, has been reported in patients taking Rituxan, an arthritis and cancer drug marketed by Genentech and Biogen Idec ( BIIB), and Tysabri, a multiple sclerosis drug marketed by Biogen Idec and Elan ( ELN), according to The Associated Press.

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