Nabi Pharmaceuticals have reached an exclusive option and licence agreement with GlaxoSmithKline for their smoking vaccine NicVax.
The deal, potentially worth more than £340 million, including a £27-million upfront payment to Nabi, will also see Glaxo start work on developing a second-generation version of the drug.
NicVax works by training the immune system to make antibodies that attach themselves to nicotine, thus preventing the chemical from reaching the brain so people can quit smoking without the fear of being tempted to start again.
The deal was approved by Nabi shareholders on Tuesday, with shares in the company rising 4p after it was announced. Shares in London-based Glaxo fell by 9.3p afterwards.