LONDON (Dow Jones) - Shares of British biotech Protherics PLC surged more than 50% on Thursday after AstraZeneca PLC agreed to pay up to $338 million for the rights to a drug to treat a potentially lethal blood infection.

Protherics (PTIL) said it's won a late-stage licensing deal with AstraZeneca ( AZN) valued at as much of 195 million pounds to license its anti-sepsis product CytoFab, which is being prepared for a Phase III trial.

Protherics shares were recently up 49.5% at 84 pence in London, and traded as high as 87p.

"This is (a) stunningly good licensing deal with a heavy upfront payment and decent royalty rates as well as ongoing manufacturing rights," said Erling Refsum, an analyst for Nomura Securities in London .

AstraZeneca will make an initial payment of 16.3 million pounds, a 7.5- million-pound equity investment and payments of as much as 171 million pounds depending on milestones.

In addition, Protherics will get royalties of 20% of net sales.

AstraZeneca plans to start the pivotal Phase III study for CytoFab in the U.S. and E.U. in 2007.

AstraZeneca recently was down 0.04% in London trade.

(END) Dow Jones Newswires

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