The deal gives the acquisitive specialty pharma group a position in the emerging field of optogenetics, the use of light to switch genes on and off and thereby control the activity of neurons and other cells.
RetroSense has put its own spin on the technology, using it to create cells that are light sensitive and can replace rod and cone cells in the eye that have degenerated, leading to visual impairment. The company uses a vector to transfer a photosensitivity gene called channelrhodopsin-2 to create new photosensors in retinal ganglion cells.
The company's lead therapeutic candidate is RST-001, a gene therapy for the inherited eye disease retinitis pigmentosa that - if early tests are borne out in ongoing Phase I/II clinical trials - promises to actually reverse loss of vision in these patients. It is also being developed as a treatment for age-related macular degeneration (AMD).
Allergan chief executive Brent Saunders - who was formerly head of eyecare specialist Bausch + Lomb - has made no secret of his intention to bulk up the company's ophthalmology portfolio since a $160bn merger deal with Pfizer fell through earlier this year.
Allergan is already a big player in ophthalmology and optometry - its largest sales category - but wants to add to its established portfolio of eyecare pharmaceuticals currently headed by dry eye therapy Restasis (cyclosporine) which made sales of $1.3bn last year.
With Restasis facing competition in the market from Shire's recently-approved Xiidra (lifitegrast) - also tipped to make $1bn-plus in peak sales - Allergan is investing in a new generation of ophthalmic treatments.
In August it announced a deal to buy privately held biotech ForSight Vision5 for $95m upfront, adding a delivery device to reduce elevated intraocular pressure in glaucoma patients. Last year it bought another glaucoma device developer AqueSys for $300m upfront, shortly after snapping up Oculeve to add an implant for patients with dry eye disease to its portfolio in a $125m deal.
Earlier eyecare deals include a $1.4bn licensing deal with Swiss biotech Molecular Partners in 2012, which gave Allergan its DARPin candidates for AMD and related conditions. That portfolio is headed by Phase III candidate abicipar, which is also considered to have blockbuster sales potential.
"The RST-001 programme and its optogenetic gene therapy approach could be a real breakthrough in the treatment of unmet needs across a host of retinal conditions," said Saunders.