Ropes & Gray and Sullivan & Cromwell are acting in connection to Pfizer’s purchase of Connecticut-based migraine drug producer Biohaven Pharmaceuticals for $11.6bn, the company’s largest acquisition since 2016. 

The proposed deal, expected to close by early 2023, will see Pfizer acquire the remaining Biohaven shares left over after it invested $350m in exchange for 2.6% of Biohaven’s common stock in connection to the commercialisation of its migraine pills. 

The deal includes the purchase of Biohaven’s fast-selling migraine medication Nurtec, which is approved in the EU under the trade name Vydura, as well as another treatment for migraine on track for approval in the US in Q2 this year.

The acquisition is the largest for Pfizer since it bought cancer drug company Medivation for $14bn in 2016. Ropes & Gray, which advised Pfizer in connection to the Medivation deal, has worked for the pharma giant on a number of big-ticket deals, including its $6.7bn acquisition of clinical-stage drug developer Arena Pharmaceuticals in November. 

Ropes & Gray this time fielded an eight-partner team to advise Pfizer, including Emily Oldshue (M&A), Amanda Austin (life sciences), William Michener (capital markets), David Saltzman (tax), Renata Ferrari (employment) and Joshua Oyster (life sciences regulatory and compliance). 

Antitrust partner duo Ruchit Patel and Michael McFalls also worked on the deal alongside a supporting cast of associates and counsel. 

Sullivan & Cromwell’s team is being led by corporate partners Frank Aquila and Scott Crofton, securities partner Robert Downes, tax partner Davis Wang and executive compensation partner Matthew Fiestedt. The partners are being assisted by seven associates across the same practice areas, as well as two from the firm’s intellectual property practice. 

The firm previously acted on Biohaven’s behalf in connection to its $250m stock offering under the stewardship of capital markets group co-leader Robert Downes in early 2020. 

Nick Lagunowich, global president of Pfizer’s internal medicine division, said the deal “builds on our legacy of delivering breakthroughs for patients living with complex pain disorders and diseases that disproportionately impact women”. 

As part of Pfizer, Biohaven will continue to operate under the same name, while the chairman and chief executive positions will be retained by Vlad Coric, who was named chairman of the board of directors in late 2021 after six years as CEO.