U.S. biotech Chiron has rejected a $4.5 billion takeover bid proposed last week by the Swiss drug giant Novartis. Chiron said in a statement Tuesday, "The independent directors . . . have determined that this offer is inadequate." Last week, Novartis offered to buy the roughly 58 percent of Chiron stock that it doesn't already own for $40 a share in cash. At press time, Novartis had yet to comment concerning Chiron's latest statement. Chiron has struggled in recent months and just broke even in the second quarter of 2005 after the company encountered problems in producing enough of its flu vaccine due to problems at manufacturing plants in Germany and the U.K. However, after a favorable FDA inspection report of a Chiron plant in Liverpool, England, the company is expected to start supplying its flu vaccine again for the 2005-2006 season.