Astra Zeneca ( AZN ) has begun succession planning for Pascal Soriot, its chief executive of six years, after pressure from shareholders, the Times of London reports. The drug maker, which suffered the failure of a big lung cancer trial last week, has engaged headhunters to assess internal candidates. However, Soriot is not expected to leave imminently, despite rumors last year linking him to Teva Pharmaceutical, but shareholders have warned the company needs to prepare. Recently, Soriot said he has "no plans to move on."