Complex sentence: GSK received an advance copy from one of the journal's peer reviewers, a GSK consultant; company executives reportedly tried to persuade Nissen not to publish it, during a meeting that Nissen recorded.
Split into simpler sentences: GSK received an advance copy of the article from one of the journal's peer reviewers, a GSK consultant. Company executives reportedly tried to persuade Nissen not to publish it, during a meeting that Nissen recorded.