Cloudbreak Pharma Inc., recently announced topline results from the phase 3 study evaluating CBT-001 in patients with pterygium.
First up: the company.
Incorporated in the Cayman Islands, the clinical-stage ophthalmic drug developer has its U.S. headquarters in Irvine, California, under the name ADS Therapeutics LLC (its wholly-owned subsidiary).
Its focus: Developing pipeline candidates targeting anterior- and posterior-segment ocular diseases, including pterygium, pinguecula, pediatric progressive myopia, presbyopia, and more.
- See here for a full look of investigational assets and respective ophthalmic disease indications.
Wasn’t Cloudbreak in the news earlier this year?
Indeed. In February we reported that the FDA cleared Cloudbreak’s Investigational New Drug (IND) application for CBT-199 for the treatment of presbyopia.
However: Since that update, no further details have been released regarding any trial design / setup, a start date, or an anticipated topline data readout.
Noted. Moving on to CBT-001.
CBT-001 is a novel multi-kinase-inhibitor (MKI) eye drop under clinical development for the treatment of pterygium, which has no FDA-approved pharmacologic therapies.
Currently, most patients are treated for their symptoms using artificial tears, prescription dry eye products and/or off-label NSAIDs or corticosteroids, or pterygium surgery.
- But with these options: Significant limitations exist for long-term use.
So how does this drop work?
Leveraging Cloudbreak’s MKI platform, CBT-001 simultaneously targets the following angiogenic, fibrogenic, and inflammatory drivers of the disease, rather than just providing symptomatic relief:
- vascular endothelial growth factor receptors (VEGFRs): inhibits pathological angiogenesis/vascularization
- platelet-derived growth factor receptors (PDGFRs): reduces fibroblast activation and connective tissue remodeling
- fibroblast growth factors receptors (FGFRs): suppresses further inflammatory cell signaling
And what has its prior clinical performance looked like?
In a phase 2a trial (NCT03049852), the therapy demonstrated meaningful and durable reductions in pterygium vascularity, and ocular redness, with a favorable safety profile.
After 4 weeks of treatment, key findings included:
- Mean change from baseline in pterygium vascularity scores was −0.8 ± 0.7 grade (mean ± standard deviation) in the CBT-001 0.2% cohort and 0.0 ± 0.5 grade in the vehicle arm (P < 0.001; 95% confidence interval [CI]: −1.12, −0.40).
- Red eye (the most visible, bothersome symptom reported by patients) showed significant improvement, with a 93% responder rate
- 68% of CBT-001 patients showed ≥1 grade improvement at Week 4 vs. only 13% of vehicle patients (p < 0.001)
- 60% responder rate as early as Week 2 vs. 0% in vehicle (p < 0.001), with sustained benefit through Week 16
As for adverse reactions: The most commonly reported adverse events (AEs) were ocular, mild in severity, resolved after therapy, and did not result in discontinuation.
Interesting … now talk about this phase 3 study.
CS-301 (NCT05456425) is a multi-regional, double-masked, randomized, vehicle-controlled phase 3 trial comparing two doses of CBT-001 ophthalmic emulsion (0.1% and 0.2%) administered twice daily (BID) over 24 months versus vehicle in pterygium patients aged 12+ years.
The primary endpoints include:
- reduction in conjunctival hyperemia related to the vascularized pterygium lesion at 3 months
- ;prevention of pterygium progression at 12 months.
The study protocol also includes a 12-month double-masked extension for additional safety data.
Moving on to the findings …
Topline results include data from 659 patients (58% male, 42% female) assigned to the following arms:
- CBT-001 0.1%: 164
- CBT-001 0.2%: 329
- Vehicle: 166
Both CBT-001 0.2% and 0.1% BID demonstrated statistically significant improvement in conjunctival hyperemia versus vehicle at Month 3 (p < 0.001).
- This improvement was observed as early as Week 2 and maintained through every visit up to Month 12.
In addition: The two CBT-001 doses demonstrated statistically significant improvement in prevention of progression of pterygium lesion compared to vehicle at Month 12 (p<0.001).
- Regarding lesion size, the treatment-versus-vehicle benefit was approximately 10% of baseline, and as of Month 12, the observed treatment effect had not yet reached a plateau.
What about safety?
Superficial punctate keratitis was the most commonly reported AE in the CBT-001 0.1% group (20% vs. 8% in the vehicle group), with most cases resolving following treatment with artificial tears.
- All other individual AEs occurred in 2% or fewer patients in the 0.1% group.
And while Cloudbreak did not provide specific safety data on the 0.2% dose, it did report a similar AE profile as the 0.1% dose—although at a higher incidence.
Any comments from the company?
Chief Medical Officer Abu Abraham noted that Cloudbreak is “encouraged by the performance of CBT-001 in this phase 3 trial, which demonstrated consistent, statistically significant improvements in both conjunctival hyperemia and pterygium lesion length.”
He added: “CBT-001 has the potential to become the first disease-modifying therapy in pterygium, and we look forward to engaging with the FDA as soon as practical to determine next steps for this potential first-in-class therapy.”
So! When can we expect an update?
Cloudbreak is conducting additional analyses of the phase 3 results and intends to meet with the FDA to review the study findings and discuss potential next steps for the CBT-001 development program.
- Also on the agenda: clinical and regulatory implications of the results.
And in other candidate news: CBT-004, the company’s second asset featuring the MKI platform, had a successful end-of-phase-2 meeting with the FDA in December 2025.
- The company plans to initiate a phase 3 program in Q1 2027.
As usual, stay tuned for more updates!