Sangamo Therapeutics (SGMO) shares cratered more than 50% Tuesday, a day after the biopharma firm announced that Pfizer (PFE) had pulled out of its deal to co-develop a hemophilia drug. 

Sangamo explained that it will regain development and commercialization rights to the medicine, known as giroctocogene fitelparvovec, following the decision by Pfizer to "terminate the global collaboration and license agreement between the parties."

Sangamo noted that in July, Pfizer reported a successful Phase 3 trial of giroctocogene fitelparvovec, which is an investigational gene therapy for adults with moderately severe to severe hemophilia A.

CEO Says Sangamo 'Disappointed by Pfizer's Decision'

CEO Sandy Macrae argued those results show the treatment "is well positioned for regulatory submissions and potential commercialization," and said the company is "disappointed by Pfizer's decision."  

Sangamo said it "intends to explore all options to advance the program, including seeking a potential new collaboration partner."

Shares of Sangamo Therapeutics recently traded down 53%, although they remain more than 100% higher year-to-date. Pfizer shares traded slightly higher.