Ocuphire Pharma has concluded subject enrolment in Phase IIb ZETA-1 clinical trial of its oral drug candidate, APX3330, to treat diabetic retinopathy (DR).

A transcription factor regulator Ref-1 (reduction-oxidation effector factor-1) inhibitor, APX3330 has a new dual mechanism of action.

A total of 103 patients with moderately severe-to-severe non-proliferative diabetic retinopathy (NPDR) or mild proliferative diabetic retinopathy (mild PDR) were enrolled in the trial at 25 US sites.

The randomised, multicentre, placebo-controlled, double-masked trial will analyse the safety and efficacy of APX3330 in patients with DR. 

Trial participants are categorised to receive either 600mg APX3300 or a placebo daily for 24 weeks. 

A responder assessment that studies the percentage of participants with a ≥ 2 step improvement on the DRSS score is the trial’s primary endpoint.

Analysing the central subfield thickness to evaluate effects on diabetic macular oedema, safety, tolerability and BCVA are included as secondary endpoints.

The company anticipates the 24-week primary endpoint data from the trial in the second half of this year.

Ocuphire Pharma CEO and founder Mina Sooch said: “Completion of enrolment in ZETA-1 in under a year is impressive relative to competitive DR trials over the last few years. 

“In addition, this trial marks the completion of enrollment of four late-stage clinical trials in the first few months of 2022.” 

In more than 11 prior trials, APX330 demonstrated to possess favourable safety and tolerability profile in healthy subjects, hepatitis and cancer patients.

In November last year, the company enrolled the first subjects in the Phase III MIRA-3 trial of Nyxol Eye Drops for reversing pharmacologically induced mydriasis (dilation of the pupil).

Nyxol is a 0.75% ophthalmic formulation of phentolamine mesylate and could lower the pupil size by hindering or relaxing the iris dilator muscle.