(Reuters). – Drugmaker Pfizer (NYSE:) and gene-editing company Beam Therapeutics will work together in a $1.35 billion deal to create therapies for rare genetic disorders.

The companies announced Monday that Beam would receive $300 million upfront and will be conducting lead research until three additional therapy targets have been identified.

Pfizer will be then responsible for developing and regulating the activities related to the targets. The option is available for Pfizer to choose from exclusive worldwide licensing for each.

Beam Biotech, which was listed in February 2020 and is a biotech company, employs gene-editing technology for the development of treatments for rare genetic disorders.

Gene therapy is a method to treat certain diseases. It replaces the altered or missing gene in the patient’s cell with healthy copies. This makes them some of the most costly drugs on the market.

For six of its research programs, Beam formed a partnership last year with Apellis Pharmas (NASDAQ:).

Beam will receive 35% of total net profit and costs if it chooses to develop and commercialise any Pfizer target.

Beam can also receive royalty payments on net sales of each target. The agreement has an initial term that is four years, but may be extended up to an additional one.