RhNGF eye drops safe but does not confer significant neuroenhancement in glaucoma

Treatment with topical recombinant human nerve growth factor (rhNGF) is safe and well tolerated but falls short of providing neuroprotection in patients with glaucoma, according to the results of a phase Ib study.

Sixty patients (average age 66.1 years, 38 percent female) with open-angle glaucoma were randomized to receive either 180 μg/mL rhNGF or vehicle control eye drops in both eyes, administered three times daily for 8 weeks, with a 24-week post-treatment follow-up. Although both eyes were studied and dosed, one eye was selected as the study eye.

Primary endpoints were safety (adverse events) and tolerability (patient-reported outcomes). Secondary endpoints included best corrected visual acuity (BCVA), Humphrey visual field, electroretinograpy (ERG), and optical coherence tomography (OCT) of retinal nerve fibre layer (RNFL) thickness at baseline, after 8 weeks of treatment, and at 4 and 24 weeks after treatment (12 and 32 weeks total).

During the entire 32 weeks, there were no treatment-related serious adverse events (ie, unexpected severe progression of optic neuropathy), events affecting ocular function or pressure, and drug-related systemic toxicities documented.

Topical high-dose rhNGF was tolerated well, with a low symptom burden mainly eliciting periocular ache (52 percent in the rhNGF group and 5 percent in the placebo group). Three patients (7.5 percent) discontinued treatment due to discomfort, of whom one patient (2.5 percent) prematurely withdrew from the study.

The treatment and placebo groups had no significant differences in the global indices of Humphrey visual field, as well as in total, quadrant, or clock-hour mean RNFL thickness. However, both of these measures showed nonsignificant trends that favoured rhNGF.

The trends detected in the study warrant an analysis for efficacy in a neuroprotection trial.