Biogen memo examined

US federal investors are examining a memo to see what officials at Biogen Idec Inc, the third-largest US biotechnology company, knew about the condition of two patients before the withdrawal of the drug Tysabri, the Wall Street Journal reported.

Securities and Exchange Commission investigators were trying to see if and when four executives involved in selling options in February knew about the condition of two patients given the drug as part of a clinical trial, the Journal said.

The memo indicated that the patients first developed symptoms of a rare brain disorder in December, before undergoing tests in February; one died that month and the second is showing signs of improvement. Tysabri, used for treating multiple sclerosis, was withdrawn on February 28, the day the memo was written, the paper said.