Dec 30 (Reuters) - Sangamo Therapeutics said on Monday that partner Pfizer has terminated their hemophilia A gene therapy co-development agreement, sending its shares down 54.3% in extended trade.

Sangamo added that it has now regained the rights to the therapy's development and would explore all options to advance the program, including seeking a potential new collaboration partner.

The agreement's termination has delayed Sangamo's chance to bring a product to market, as Pfizer was expected to submit data for potential approval of the therapy in early 2025.

The decision was made following an extensive analysis of clinical trial results, expert feedback and a slow uptake of hemophilia A gene therapy in patients with moderate to severe disease and there is currently limited interest in another gene therapy option for the specified patient population, Pfizer said in a statement.

"We believe it is best to re-dedicate our time and resources to those assets and treatments that will have the greatest impact on patients and the greatest chance of commercial success," Pfizer added.

Earlier this year, Pfizer had revealed data from the therapy's late-stage study, which showed that the treatment reduced the number of annual bleeding episodes in patients with the rare disorder.

Sangamo said that the collaboration and license agreement with Pfizer would officially terminate on April 21 next year. All trial participants will continue to be monitored as planned during the transition period.

Hemophilia A, affecting about 25 in every 100,000 male births globally, is caused by a faulty gene that disrupts the production of clotting factors, leading to spontaneous and severe bleeding after injuries or surgery.

Sangamo said it remains focused on advancing its other therapy for the inherited disorder Fabry disease toward submission for potential approval in the second half of 2025.