This clinical trial is focused on studying a condition known as hemophilia B, which is a genetic disorder that affects the blood’s ability to clot properly. People with this condition can experience excessive bleeding even from minor injuries. The study is specifically looking at adult males with moderately severe to severe forms of this condition. The treatment being tested is a gene therapy called fidanacogene elaparvovec, also known by its code name PF-06838435. This therapy involves a single infusion of a solution that contains a modified gene designed to help the body produce more of a protein called Factor IX, which is essential for blood clotting.

The purpose of the study is to evaluate how effective and safe this gene therapy is for individuals with hemophilia B. Participants in the study will receive a single infusion of the gene therapy and will be monitored over a period of time to see how their condition changes. The study will look at various factors, such as the number of bleeding episodes participants experience and their overall health, to determine the therapy’s effectiveness. Participants will also be observed for any side effects or adverse reactions to the treatment.

The study is designed to provide valuable information about the potential benefits and risks of using fidanacogene elaparvovec as a treatment for hemophilia B. By participating in this research, scientists hope to find a new way to help people with this condition manage their symptoms and improve their quality of life. The study will continue for several years to gather comprehensive data on the long-term effects of the therapy.