Pfizer has filed a lawsuit against Metsera and Novo Nordisk, seeking to block Novo's rival takeover bid unveiled Thursday. Why it matters: The fight over obesity startup Metsera is heating up and could be headed to court — a scenario that may stall the deal's completion for years.

Reporting by Jacob Gronholt-Pedersen and Stine Jacobsen, writing by Louise Breusch Rasmussen, editing by Essi Lehto

Following the announcement, Metsera said the offer from Novo Nordisk was "superior", as defined in its merger agreement with Pfizer, and gave Pfizer four business days to submit a new, higher offer.