The agency said it's asked the company to put a black-box warning label on the drug, which is sold under the brand name Xolair. A black box warning is the FDA's strongest warning.
Xolair was approved in 2003 to treat adults and adolescents with moderate to severe persistent asthma related to allergies whose symptoms are inadequately controlled with inhaled steroids.
A company spokesman couldn't immediately be reached.
Genentech shares recently rose 8 cents to $87.02.
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