Phase I study of polyhexanide seeks safety, tolerability characteristics for patients with AK

The study focused the safety and tolerability of increasing doses of polihexanide eye drops in order to choose a dose that would be tested in a phase III clinical trial in patients with acanthamoeba keratitis.

A study of polyhexanide in healthy volunteers focused on evaluating the safety and tolerability of increasing doses of the eye drops in order to choose a dose that would be tested in the phase III clinical trial in patients with acanthamoeba keratitis (AK).

SIFI, an ophthalmic company based in Italy, published clinical results from its Phase I trial of polihexanide in in the peer-reviewed journal British Journal of Ophthalmology.

According to the company, results of the trial showed a good safety and tolerability profile including the 0.08% dose, the highest tested.

The Phase I randomly assigned, double-masked, controlled trial was conducted on 90 healthy volunteers (NCT02506257). According to the company, participants were treated with eye drops of either polihexanide 0.04%, 0.06%, 0.08%, or placebo (1:1:1:1). There were no significant differences in dose-limiting adverse events (AEs) among treatment groups. There were also no specific trends in AEs between each dose tested in the study.

"This important achievement has provided a clear target dose, that is currently being tested in the large Phase III trial," Sebastiano Giuffrida, head of Clinical Development at SIFI SpA, said in a statement. “Based on the safety data found in the Phase I trial, we are confident that polihexanide 0.08% can be safely used to treat all clinical AK presentations.”

Prof. John Dart, of Moorfields Eye Hospital and University College London, pointed out that despite 20 years international experience with polihexanide 0.02% for AK, there are concerns about its potential toxicity.

“Our Phase I study has shown that a four-fold higher polihexanide concentration, given intensively over 2 weeks, can be used safely in healthy subjects and is therefore unlikely to cause unacceptable adverse events in patients with AK,” he said in a statement. “This finding has allowed us to evaluate polihexanide 0.08%, expected to be more effective than 0.02%, in our Phase III trial.”

In November, SIFI announced the completion of enrolment (n=135) in the pivotal Phase III ODAK clinical trial of polihexanide 0.08% in AK patients (NCT03274895). Topline results are expected in the second half of 2021.

Polihexanide has been granted orphan drug designation in both the European Union and the United States. If approved, it will become the first medicine to be licensed for AK globally.

"We believe that our polihexanide program has the potential to be a major part of our growth trajectory going forward," Fabrizio Chines, chairman and CEO, said in a statement. “Apart from being a terribly devastating disease, AK is clearly an area of unmet medical need. Coupled with our progress in the Phase III trial, we are poised to be first to the market with our innovative monotherapy and help halt AK's devastating consequences.”

SIFI is currently evaluating different options for the commercialization of polihexanide 0.08%, including potential out-license agreements outside its core markets.

Polihexanide will be the first licensed drug for the treatment of AK. Polihexanide is a polymer and acts on both the trophozoites and cysts of the protozoan Acanthamoeba. It is developed in the 0.08% high dose which make it possible to administer as monotherapy eye drops in a single dose container. In contrast, current treatment protocols include various non-standardized unlicensed alternatives and usually involve combination therapy.