Dec 23 (Reuters) - A patient who was being treated with

Pfizer's ( PFE ) hemophilia drug, Hympavzi, as part of a

long-term study died after experiencing serious side effects,

the company said.

The individual died on ‌December 14 after suffering a stroke

followed by a brain hemorrhage, according ​to the European

Haemophilia Consortium, a patient support group.

The ‍patient was enrolled in a study ⁠that was testing

Hympavzi ⁠in patients with hemophilia A or B with or without

inhibitors.

"Pfizer ( PFE ), together ‌with the trial investigator ​and the

independent external Data Monitoring Committee, are actively

gathering information to better understand the complex,

multi-factorial ⁠circumstances surrounding this occurrence," ‍the

company ​said in a statement.

The therapy, a once-a-week injection, gained U.S. approval

last year to prevent or reduce ‍bleeding episodes in hemophilia A

or B patients aged 12 years and older by targeting

blood-clotting proteins.

Pfizer ( PFE ) does not anticipate any impact to safety for patients

treated with the drug based on its current knowledge ​and ‍the

overall clinical data collected to date, the company said.

People with hemophilia have a defect in ​a gene that

regulates the production of proteins called clotting factors,

causing spontaneous and severe bleeding following injuries or

surgery.

Earlier this year, Pfizer ( PFE ) said it would halt global

development and commercialization of its hemophilia gene

therapy, Beqvez, citing soft demand from patients ​and their

doctors.

Beqvez, a one-time therapy, was approved in the U.S. for the

treatment of adults with moderate to severe hemophilia B.