Patients with glaucoma have two main options: eye drops and surgery, both of which aim to reduce pressure in the eye that can lead to vision loss. Problem is, these treatments don’t work for everyone, including children born with glaucoma stemming from a genetic disorder and people who have glaucoma without high eye pressure.
That’s because current treatments only address three factors that account for about one-third of intraocular, or eye pressure, said Qlaris Bio CEO Thurein Htoo. Those factors include aqueous humor production—or how much fluid is made in the eye—and outflow of that fluid either through the eye’s meshlike drainage system or through the uveoscleral pathway, where fluid seeps through, around and between tissues rather than through tubes and channels.
The fourth, unaddressed component of eye pressure is called episcleral venous pressure, or EVP.
“It happens to be the single largest component of intraocular pressure,” Htoo said, adding that it accounts for about 50% to 60% of eye pressure. Because current treatments don’t tackle EVP, there is limit to how much eye pressure they can alleviate.
Qlaris is kicking off a phase 1/2 study of a treatment designed to lower EVP, and it recently raised $25 million to get the treatment, called QLS-101, through development.
Htoo likens the eye to a bathtub and the water filling it to the aqueous humor, or fluid, in the eye.
“Water can flow out through various routes, such as the main drain at the bottom of the tub, or auxiliary drains at the side of the tub to prevent overflowing,” Htoo said. While other drugs aim at turning off the faucet to reduce the amount of water going into the tub, or removing hair from the drain to help water get through it, QLS-101 relieves pressure by widening the pipes beyond the drain and allowing more water to flow out of the tub.
QLS-101 is a prodrug of an ATP-sensitive potassium channel modulator, meaning the medicine, given as a topical eye drop, is metabolized within the eye to produce the drug. The drug binds to ATP-sensitive potassium channels in the episcleral blood vessels found in the white outer layer of the eye. This leads those blood vessels to dilate and relieve pressure.
“It allows us to take a more personalized approach to glaucoma therapy, rather than the all-comers approach in the past,” Htoo said.
Qlaris is developing QLS-101 as a new treatment for glaucoma patients who don’t get relief with other treatments. Its phase 1/2 study is testing three concentrations of QLS-101 given once a day against a conventional glaucoma treatment in patients with primary open angle glaucoma. But it will start two more phase 1/2 trials later this year in patients with normal-tension glaucoma, whose disease damages the optic nerve while their eye pressure stays in the normal range, and in adults with Sturge-Weber syndrome, in which a genetic mutation leads to intractable levels of glaucoma and other symptoms.
Beyond these indications, the drug could potentially be used as in combination with other eye drops or eye implants in other types of glaucoma to get even better results.