Pfizer has kicked off a late-stage trial assessing efficacy and safety of the investigational gene therapy fidanacogene elaparvovec for the treatment of haemophilia B.

The Phase III lead-in study has been initiated following completion of the transfer of Spark’s haemophilia B programme to the drug giant.

The trial will assess the efficacy and safety of current factor IX prophylaxis replacement therapy in the usual care setting. The data gathered from this will then serve as the within-subject control group for those patients that enroll into the next part of the Phase III study, which will evaluate fidanacogene elaparvovec for the treatment of the condition.

The interventional portion of this pivotal Phase III study will enroll patients who have completed at least six months in the lead-in study, Pfizer said.

"With the lead-in study now open and actively recruiting patients, we are excited to begin our Phase III programme evaluating fidanacogene elaparvovec for the treatment of hemophilia B,” said Brenda Cooperstone, senior vice president and chief development officer, Rare Disease, Pfizer Global Product Development.

“The current data suggest immense promise for the use of this potential one-time treatment option. We look forward to the opportunity to continue the progress achieved by Spark Therapeutics for patients living with hemophilia B.”

Haemophilia is a rare genetic bleeding disorder that causes the blood to take a long time to clot because of a deficiency in one of several blood clotting factors. People with hemophilia are at risk for excessive and recurrent bleeding from modest injuries, which could be life threatening.