Between 2000 and 2010, Pfizer racked up three of the ten largest biopharmaceutical deals of all time, with a US$90 billion acquisition of Warner-Lambert, a $60 billion merger with Pharmacia and a $68 billion acquisition of Wyeth. The last deal, especially, was aimed at bolstering Pfizer’s flagging pipeline and protecting its revenue base from an upcoming patent cliff. More than a decade on — having walked away from an attempted takeover of AstraZeneca and a merger with Allergan — the company is celebrating an R&D turnaround. Pfizer CSO Mikael Dolsten has overhauled the firm’s scientific approach, focusing on five therapeutic areas, halving the number of candidates the company has in the clinic, and expanding its modality capabilities beyond the small molecules it used to focus on. And he believes the results are in: Pfizer’s phase II success rate has tripled in recent years, he said at a recent investor day. Dolsten spoke with Asher Mullard about Pfizer’s clinical success rate, its focus on speedy drug development and its approach to modality expansion in recent years.