Eye Drops Slowed Pterygium in a Phase 3 Trial. Until Now, Only Surgery Could Remove It.
No drug is approved by the U.S. Food and Drug Administration (FDA) to treat pterygium. On November 4, 2026, Cloudbreak Pharma reported that its eye drop, CBT-001, eased redness and held back the growth itself in a phase 3 trial of 659 patients. If regulators agree, it would be the first medicine aimed at the disease rather than its symptoms.
Pterygium is a wing-shaped growth that starts on the conjunctiva, the clear tissue over the white of the eye, and creeps onto the cornea, the clear front window. Ultraviolet light is the main cause, according to the American Academy of Ophthalmology's EyeWiki. It brings redness, irritation and dry eye, and a large one can blur vision. Patients today get artificial tears, dry eye prescriptions or off-label anti-inflammatory drops for comfort. Surgery is the only way to take the growth off. CBT-001 is a multi-kinase inhibitor, a drug that blocks several of the enzymes cells use to pass along growth signals.
What the trial found
The trial, CS-301, was randomized and double-masked: patients were assigned by chance, and neither they nor the doctors knew who got what. Patients used drops twice a day. Cloudbreak assigned 164 to the 0.1% dose, 329 to the 0.2% dose and 166 to the vehicle, an identical drop with no drug in it. Enrollment began in the U.S. in June 2022 and later spread to China, New Zealand, Australia and India. The group was 58% male and 42% female.
The trial had two main goals, called co-primary endpoints. The first was conjunctival hyperemia, the redness around the growth, at Month 3. The second was how much the lesion lengthened by Month 12. Both doses beat the vehicle on both goals, each with a p value under 0.001, which means chance is an unlikely explanation. Redness improved as early as Week 2 and stayed better through Month 12. On lesion size, the drug's edge over the vehicle came to about 10% of baseline, and the company says that edge had not leveled off at Month 12. Chief Medical Officer Abu Abraham said, "CBT-001 has the potential to become the first disease-modifying therapy in pterygium."
The cost and the limits
The drops have a price in comfort. The most common side effect was superficial punctate keratitis, tiny spots of damage on the corneal surface. It showed up in 20% of patients on the 0.1% dose and 8% on the vehicle, and most cases cleared with artificial tears. No other single side effect topped 2% on the lower dose. The 0.2% dose had a similar pattern at a higher rate, which the release does not give.
These are topline results, the first headline numbers a company releases before the full analysis. No outside scientist has reviewed the full data, and no journal paper exists yet. The release does not break results down by country, age or lesion size. It also does not say how many lesions shrank and how many grew more slowly than they would have.
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A daily drop before the operating room
Surgery fixes the eye for now but does not always fix it for good. EyeWiki reports that pterygium returns in up to 80% of eyes when surgeons simply cut it away, and in about 5% to 10% when they patch the spot with a graft of the patient's own conjunctiva. A drop that keeps a small growth small could delay the operation or spare someone from a repeat.
Redness is what patients notice
For many patients, the measured length of the lesion matters less day to day than the red, gritty eye they see in the mirror. Faster relief there may drive whether people keep using a twice-daily drop for months. The trade-off doctors will weigh is that the drug's main side effect lands on the same corneal surface the treatment is meant to protect.
Five countries, 66 clinics, more data to come
The ClinicalTrials.gov record lists 66 sites: 20 in the U.S., 10 in China, 6 in India, 5 in Australia and 3 in New Zealand. The company says dosing runs 24 months, with a 12-month masked extension for added safety data. The registry lists the study as active and estimates full completion at the end of 2027, so the longer follow-up will show whether the gap between drug and vehicle keeps widening.
A company claim under a regulatory cloud
Every efficacy and safety figure here comes from Cloudbreak, and the release says its data have not been audited. The company is also under investigation. On September 10, 2026, Hong Kong's Securities and Futures Commission (SFC) suspended trading in its shares, citing serious concerns that the July 2025 IPO may have been rigged to create a false impression of demand, The Standard reported. The shares had fallen 88% from the HK$10.10 offer price. The probe concerns the share sale, not the trial, but it is one more reason to wait for independent review.
A common condition in sunny places
Cloudbreak estimates that pterygium affects nearly 1 billion people worldwide and 13 million in the U.S., with about 2.5 million U.S. diagnoses a year. Those are company figures. EyeWiki links the condition to UV light, life near the equator, dry climates and outdoor work. Even a modest benefit could reach a large number of people, and a bottle of drops travels to places where eye surgeons are scarce.
What This Does and Does Not Mean
The trial gives pterygium its first controlled evidence that a drop can slow the growth and calm the redness, with both doses clearing both goals. It does not make CBT-001 a treatment yet. The effect on lesion size was modest, one in five patients on the lower dose had corneal irritation, and the numbers have not been checked outside the company. Cloudbreak says it is running more analyses and will meet the FDA as soon as practicable. That meeting, and a full peer-reviewed paper, will decide what the result means for patients.
Frequently Asked Questions
What is pterygium?
Pterygium is a wing-shaped growth that starts on the conjunctiva, the clear tissue over the white of the eye, and spreads onto the cornea. Ultraviolet light is the main risk factor. It can cause redness and irritation, and a large one can blur vision. Surgery is the only way to remove it.
What did the CBT-001 phase 3 trial show?
In a 659-patient trial, both doses of Cloudbreak Pharma's CBT-001 eye drops beat inactive drops on both main goals: less eye redness at Month 3 and less lesion growth at Month 12, each with p below 0.001. The company says the lesion benefit was about 10% of baseline and had not leveled off by Month 12.
What are the side effects of CBT-001?
The most common side effect was superficial punctate keratitis, tiny spots of damage on the corneal surface. It affected 20% of patients on the 0.1% dose versus 8% on inactive drops, and most cases cleared with artificial tears. The 0.2% dose had similar side effects at a higher rate the company did not state.
Is CBT-001 approved?
No. The results are topline data from the company and have not been peer-reviewed. Cloudbreak plans to meet with the FDA to discuss next steps. No drug is FDA-approved to treat pterygium.