Allen & Overy (A&O) has landed its first cross-border instruction from US pharmaceuticals company Pfizer, advising it on the European elements of a $575m (£315m) deal.

The firm, which had previously only advised on UK issues, rolled out teams from six of its European offices to advise Pfizer on the disposal of its allergy testing arm to the independent European private equity firm Titon and PPM Ventures, the private equity arm of Prudential Corporation.