Cloudbreak Pharma, an Irvine, California based ophthalmic drug company listed in Hong Kong (HKEX: 2592), announced topline results on November 4 from CS-301, its multi regional, double masked, randomised, vehicle controlled Phase 3 trial of CBT-001 in pterygium, the fleshy growth on the surface of the eye associated with ultraviolet exposure. The trial (NCT05456425) enrolled 659 patients and compared two doses of the multi kinase inhibitor eye drop, 0.1 percent and 0.2 percent, given twice daily, against vehicle.
Both doses met both primary endpoints. Each showed a statistically significant improvement in conjunctival hyperemia, the redness of the white of the eye caused by the vascularised lesion, at month 3 against vehicle (p below 0.001), with improvement seen as early as week 2 and maintained at every visit through month 12. Each dose also significantly prevented progression of pterygium lesion length at month 12 (p below 0.001). The company said the treatment against vehicle benefit on lesion size was about 10 percent of baseline and had not yet plateaued at month 12, and described the findings as the first demonstration of disease modifying activity in pterygium. Detailed data have not been shared.
The most common adverse event was superficial punctate keratitis, a disorder of the corneal surface, reported in 20 percent of patients on the 0.1 percent dose against 8 percent on vehicle, with most cases resolving with artificial tears, the company said.
There is no FDA approved therapy for pterygium, which is otherwise managed by observation and surgery. Cloudbreak said it intends to meet with the FDA as soon as practicable to review the findings and discuss next steps, including the clinical and regulatory implications. In March the company said it planned to start a second Phase 3 trial in the third quarter of 2026 and complete it in late 2028, according to Fierce Biotech, so a filing on one trial alone looks unlikely. The result also lands on a company under strain: trading in Cloudbreak’s Hong Kong shares has been suspended at the direction of the Securities and Futures Commission amid an investigation connected to its IPO, Fierce Biotech reported, which limits its ability to raise the money a second trial and a launch would require.