Tarsus places $800m wager on Alkeus' Stargardt therapy

Tarsus has agreed to buy Alkeus in an $800 million deal that will give it rights to a drug for rare eye disorder Stargardt disease that has "blockbuster potential."

The takeover revolves around Alkeus' gildeuretinol acetate (ALK-001), an oral therapy for Stargardt disease that is designed to interrupt a process that leads to the accumulation of toxic metabolites in retinal photoreceptor cells – vitamin A dimers such as bisretinoids and lipofuscin – that causes them to degenerate.

Tarsus is paying $450 million upfront for Alkeus – made up of $270 million in cash and $180 million in stock – with another $350 million on offer if gildeuretinol makes it onto the market and records a first commercial sale.

Alkeus' drug showed in the phase 2 TEASE-1 study in Stargardt patients with atrophic lesions at baseline that it could slow down the rate of lesion development by 29.5% versus placebo.

Meanwhile, TEASE-2 trial that slowed down the loss of photoreceptor cells in moderate Stargardt disease patients without atrophic lesions by around 28% over two years compared to control, although the difference failed to reach statistical significance. Investigators blamed that, however, on the heterogeneous patient cohort in the study, for example an age range that went from eight to 70.

Undeterred by the mixed results, Alkeus has started a pivotal trial of gildeuretinol (NORTHSTAR) that will enrol around 230 patients aged eight to 45 living with advanced Stargardt disease, which affects around 50,000 people in the US and has no approved therapies. The study will look at retinal atrophic lesion growth over 24 months, along with visual acuity.

Top-line results from NORTHSTAR on are expected in 2029, putting Alkeus' drug behind rival therapies for Stargardt, including Belite Bio's tinlarebant, another drug designed to reduce the accumulation of vitamin A-based toxins that has already reported data from the phase 3 DRAGON trial.

If the merger goes through, gildeuretinol will give Tarsus another clinical-stage drug candidate to go along with TP-04 for the potential treatment of ocular rosacea, TP-05 as an oral tablet for the potential prevention of Lyme disease – both of which are in phase 2 testing – along with IRX-101, an ocular antiseptic that is being developed to reduce post-procedural pain and corneal toxicity in patients receiving injections into the eye and stems from the company's acquisition of iRenix Medical.

Tarsus already generates revenues from Xdemvy (lotilaner), used to treat blepharitis (eyelid inflammation) caused by Demodex mites, sales of which grew 69% to $174 million in the second quarter of this year.

"Our strategy has been to build a leading eye care company by identifying significant diseases where patients have been starving for innovation and bringing forward medicines with the potential to change the standard of care," said Tarsus' chief executive Bobby Azamain.

"We believe gildeuretinol has the potential to be a transformational medicine for Stargardt disease and complements the retina capabilities we are already building through IRX-101."