Syncona has announced that its company Nightstar Therapeutics has agreed to be acquired by Biogen.

The agreement will value at approximately $25.50 per share in cash, or $800 million, giving Biogen a clinical pipeline of gene therapy candidates in ophthalmology.

The sale of the company is predicted to generate £254.6 million of proceeds for Syncona and is expected to complete in the second quarter of 2019.

Biogen chief executive Michel Vounatsos has said the deal will "accelerate our entry into ophthalmology by contributing two mid to late stage gene therapy assets, with the potential to create long-term shareholder value.”

Martin Murphy, chief executive of Syncona, said: "In the six years since Syncona founded Nightstar, the company has established itself as one of the global leaders in retinal gene therapies. It is a strong example of our differentiated approach of founding, building and funding global leaders in life science and we look forward to seeing Nightstar work to deliver transformational treatments to patients during the next phase of its development with Biogen.”

Nightstar's is a leading clinical-stage gene therapy company focused on developing and commercialising novel one-time treatments for patients suffering from rare inherited retinal diseases, whose lead product candidate, NSRREP1, is currently in Phase III development for the treatment of patients with choroideremia.

The drugmaker's second clinical programme is NSR-RPGR for the treatment of X-linked retinitis pigmentosa, while its preclinical pipeline includes NSR-ABCA4 for Stargardt disease.