Pfizer is set to launch a new study for men aged 18 years and older with hemophilia to assess the safety and efficacy of giroctocogene fitelparvovec (hemophilia A) or fidanacogene eleparvovec (hemophilia B).

The study participants with hemophilia A will have received prior treatment with giroctocogene fitelparvovec as part of a previous Pfizer study, and will not receive any study drug in this trial. Similarly, the study participants with hemophilia B will have received prior treatment with fidanacogene eleparvovec, and will not receive any study drug in this trial.

At the last update on October 6, the study had not yet started recruiting but was expected to start October 31, 2022. The estimated completion date is September 7, 2034.

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The intervention consists of testing hepatic adeno-associated virus vector integration in liver samples obtained from the participants during surgical resection or through biopsy. Primary outcome measures include the incidence of thromboembolic events, hepatic malignancy, liver abnormalities, and changes in factor activity levels. Secondary outcomes include a variety of measures such as annualized bleeding rates, vector infusions and consumption, autoimmune disorders, adverse events, mortality, and quality of life.

Read more about hemophilia therapies

Hemophilia is a rare, inherited disorder in which the blood does not clot due to the absence of clotting proteins known as factors. Most hemophilia patients are male. Hemophilia A is due to a lack of clotting factor VIII, and hemophilia B is due to a lack of clotting factor IX.

Giroctocogene fitelparvovec and fidanacogene eleparvovec are investigational gene therapies for hemophilia that are designed to deliver healthy copies of the missing or defective factors, VIII or FVIII in patients with hemophilia A and IX in patients with hemophilia B. They are known as adeno-associated virus cDNA gene therapies, and the purpose of the current study is to assess the long-term safety of these particular therapies and their impact on patient outcomes.


A study to learn about the safety and effectiveness of the study medicines called giroctocogene fitelparvovec and fidanacogene elaparvovec. October 6, 2022. Accessed November 8, 2022.