Genentech, the American subsidiary of Swiss pharmaceutical firm, Roche, has been ordered to pay an additional $200 million in punitive damages.
Two weeks ago, a Los Angeles jury told Genentech to pay $300 million to the California-based City of Hope cancer centre in a trial over drug royalty payments due under a 1976 contract.
Following Monday's decision, the biotechnology company will now have to hand over a total of $500 million (SFr750 million) to the centre.
The cancer centre had accused Genentech of fraud for failing to pay cancer royalties on drugs sold that were made by companies to which the biotechnology firm had licensed the patents.
The Roche subsidiary - which announced it would appeal against the charges - said that it would nevertheless deduct $500 million from its second-quarter earnings to cover the payment.
Genentech shares rallied after Monday's verdict, gaining $1.89, or nearly 6 per cent, to close at $34.84 on the New York Stock Exchange.
swissinfo with agencies