Biogen to Acquire Gene-Therapy Company Nightstar in $800-Million Deal

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The acquisition will establish a clinical pipeline for Biogen of gene-therapy candidates in ophthalmology.

Biogen has entered into an agreement to acquire Nightstar Therapeutics (NST), a UK-based clinical-stage gene-therapy company based focused on adeno-associated virus (AAV) treatments for inherited retinal disorders, in a deal worth $800 million, Biogen announced on March 04, 2019.

Under the proposed acquisition, Biogen will pay $25.50 in cash for each NST share. The offer represents a total transaction value of approximately $800 million on a fully diluted basis, after expected transaction expenses and anticipated cash at closing. Biogen expects to complete the acquisition by mid-year 2019.

The acquisition provides Biogen with a clinical pipeline of gene therapy candidates for ophthalmology. NST has two potentially first-in-class mid- to late-stage clinical assets as well as preclinical programs. Its lead asset, NSR-REP1, is in Phase III development for choroideremia (CHM), a rare degenerative inherited retinal disorder that leads to blindness and has no approved treatment options, according to NST.

CHM, which primarily affects males, is caused by loss of function in the CHM gene that encodes the Rab escort protein-1 (REP-1). The REP-1 protein plays a role in intracellular protein trafficking, and loss of function in the CHM gene leads to abnormal intracellular protein trafficking and impaired elimination of waste products from the retinal pigment epithelium and photoreceptors. Initially, patients with CHM experience poor night vision, and, over time, progressive visual loss ultimately leads to complete blindness. NSR-REP1 is comprised of an AAV vector administered by subretinal injection, which provides a functioning CHM gene and expression of the REP-1 protein to restore membrane trafficking and thereby slow, stop, or potentially reverse the decline in vision.

NST’s second clinical program, NSR-RPGR, is for the treatment of retinitis pigmentosa (XLRP), which is also a rare inherited retinal disease primarily affecting males with no approved treatments, the company reports. XLRP is characterized by mutations in the retinitis pigmentosa GTPase regulator (RPGR) gene leading to a lack of active protein transport in photoreceptors. This abnormality leads to loss of the photoreceptor cells, resulting in retinal dysfunction by adolescence and early adulthood and progressing to legal blindness when patients reach their 40s. NSR-RPGR is comprised of an AAV vector administered by subretinal injection which provides a functioning RPGR gene and thus expression of the RPGR protein, which is critical for protein transport in photoreceptors. The restoration of photoreceptor function is intended to slow, stop, or potentially reverse the decline in vision.


NST’s preclinical pipeline includes NSR-ABCA4 for Stargardt disease and potential programs targeting Best vitelliform macular dystrophy (Best disease) and other genetic forms of retinitis pigmentosa.

“Ophthalmology is an emerging growth area for Biogen, and we are excited about the opportunity to work with the talented employees at Nightstar to advance potentially transformative gene therapy programs for rare retinal diseases,” said Michel Vounatsos, Biogen’s CEO, in a company press release. “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. Nightstar would accelerate our entry into ophthalmology by contributing two mid- to late-stage gene therapy assets, with the potential to create long-term shareholder value.”

Source: Biogen