Biogen to buy Nightstar Therapeutics for around $800 million, adding pipeline of gene therapy candidates in ophthalmology

Biogen announced Monday an agreement to acquire Nightstar Therapeutics for $25.50 per share in cash, or approximately $800 million, giving the company a clinical pipeline of gene therapy candidates in ophthalmology. Biogen CEO Michel Vounatsos 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."

Nightstar's lead asset NSR-REP1 is comprised of an AAV vector administered by subretinal injection to provide a functioning CHM gene and expression of the REP-1 protein. The therapy is being developed for the treatment of choroideremia (CHM), with results from the Phase III STAR trial expected in the second half of 2020. Biogen noted that in an earlier Phase I/II trial, NSR-REP1 demonstrated "potentially meaningful" slowing of decline in visual acuity as compared to natural history, as well as signs of improved visual acuity in some patients.

"Ophthalmology is an emerging growth area for Biogen," Vounatsos remarked, adding "with this proposed acquisition, we are continuing to bolster our pipeline and further execute on our strategy to develop and expand a multi-franchise neuroscience pipeline across complementary modalities." The transaction comes after Biogen decided late last year to terminate a 2015 deal with Applied Genetic Technologies to develop gene-based therapies for multiple ophthalmic diseases, including X-linked retinoschisis.

Nightstar is also developing NSR-RPGR, an AAV vector administered by subretinal injection that provides a functioning RPGR gene for the treatment of X-linked retinitis pigmentosa. Results from the dose-escalation portion of the Phase I/II XIRIUS trial showed an increase in central retinal sensitivity, while the Phase II/III portion of the study is currently ongoing. Meanwhile, Nightstar's preclinical pipeline includes NSR-ABCA4 for Stargardt disease, as well as programmes targeting Best vitelliform macular dystrophy and other genetic forms of retinitis pigmentosa.

Biogen's purchase price represents a premium of 68 percent to Nightstar's closing share price on March 1. The acquisition, which requires approval from Nightstar's shareholders, is expected to complete by mid-year.

The deal comes shortly after Roche agreed to buy Spark Therapeutics for approximately $4.3 billion, gaining a number of gene therapy programmes, including SPK-8011 for haemophilia A. Meanwhile, Sarepta Therapeutics recently exercised an option to purchase partner Myonexus Therapeutics, gaining full rights to five experimental gene therapies to treat distinct forms of limb-girdle muscular dystrophy.

For related analysis, see ViewPoints: Roche pivots into gene therapy, and ViewPoints: Sarepta muscles into a new indication.

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