Okyo Pharma Limited announced positive top-line data from the recently closed 18-patient phase 2 trial of urcosimod (formerly called OK-101) to treat neuropathic corneal pain (NCP). 

The primary endpoint of the phase 2 trial was change in mean pain scores from baseline (Visit 1, Day 0) to end of treatment (Visit 4, Day 84), as measured by a VAS scale of 0-10, the company noted in a press release. 

For the per-protocol population, change in mean pain score was 5.5 in the 0.05% urcosimod group and 2.75 in the placebo group, reflecting a 2.75 delta difference between drug and placebo following the 12-week treatment period. Notably, 75% of patients treated with 0.05% urcosimod in this group achieved greater than 80% improvement in pain severity based on VAS scores. Urcosimod (0.05%) demonstrated a marked reduction in pain scores as early as Week 4, with a mean change of 5.25 compared to 3.0 in placebo group.

Moreover, for the 0.05% urcosimod group a statistically significant reduction in mean pain scores was observed from Visit 1 to the end of treatment Visit 4 (p-value = 0.025). The placebo group also showed a statistically significant improvement from baseline (Visit 1) to the final visit (Visit 4), with a p-value = 0.035. However, mean improvement seen in the placebo group was only half what was seen for the 0.05% urcosimod group (2.75 vs 5.5).

For the placebo group’s reduction from Visit 1 to the end of treatment Visit 4, 75% of those patients had only mild NCP pain scores at baseline. In contrast, all the patients in the 0.05% urcosimod group had moderate to severe NCP pain scores, indicating a more challenging baseline condition.

In the intent-to-treat population, 67% of patients in the 0.05% urcosimod group demonstrated greater than 50% improvement in pain, as measured by VAS scores, compared to 33% in the placebo group. The mean reduction in pain severity from baseline (Visit 1) to end of treatment (Visit 4), measured by VAS, was 4.2 in the 0.05% urcosimod group and 2.5 in the placebo group.

The drug-effect size of 0.05% urcosimod when compared to placebo at week 12, using Cohen-d demonstrated a strong treatment effect (Cohen-d value > 1.2). Cohen-d is a standard statistical measure used to assess and compare the effect size of the trial drug relative to the placebo.

The company said significant interest in urcosimod has been brought to its attention by sufferers of NCP during this phase 2 trial, and Okyo said it will be pushing to accelerate clinical development of urcosimod with further trials in the near future. In addition, the company said several patients from the just completed trial have also requested availability of the drug through the US Food and Drug Administration's (FDA) “Expanded Access” program (also referred to as “Compassionate Use”) which the company is planning to arrange, contingent on necessary FDA approvals, for those present patients and future patients who have specifically completed clinical trials on urcosimod.

In line with earlier findings from a previously conducted phase 2 trial to evaluate urcosimod to treat dry eye disease, results from the 0.1% drug treatment group in this trial also showed less efficacy than the 0.05% drug treatment group. Okyo said it is continuing to evaluate additional data and plans to present a larger data set from the study after ongoing analyses of the data have been completed.

This randomized, double-masked, placebo-controlled, phase 2 Proof-of-Concept trial of urcosimod to treat NCP was conducted at a single trial site at Tufts Medical Center in Boston, with Pedram Hamrah, MD, a leading expert in NCP, as principal investigator.