Effect of recombinant human nerve growth factor treatment on corneal nerve regeneration in patients with neurotrophic keratopathy

Advances in the application of smart materials in the treatment of ophthalmic diseases

Smart materials dynamically sense and respond to physiological signals like reactive oxygen species (ROS), pH, and light, surpassing traditional materials such as poly(lactic-co-glycolic acid), which have high drug loss rates and limited spatiotemporal control. These innovative materials offer new strategies for ophthalmic treatments, with core advantages including targeted delivery via ROS-sensitive nanocarriers, precise regulation through microvalves, and multifunctional integration, such as glucose-responsive contact lenses that create a "sensing-treatment" loop. However, challenges remain, like pathological microenvironment interference with material response specificity, and the need to address long-term biocompatibility and energy dependence issues. This article systematically examines three key treatment barriers: the blood-ocular barrier, immune rejection, and physiological fluctuations, while reviewing innovative smart material design strategies. Future research should focus on biomimetic interface engineering, for example, cornea mimicking nanostructures, AI-driven dynamic optimization like causal network-regulated drug release, and multidisciplinary approaches combining gene editing with smart materials. These efforts aim to shift from structural replacement to physiological function simulation, enabling precise treatment of ophthalmic diseases. Clinical translation must balance innovation with safety, prioritizing clinical value to ensure reliable, widespread application of smart materials in ophthalmology.

Preventing and treating neurotrophic keratopathy by a single intrastromal injection of AAV-mediated gene therapy

PURPOSE

Neurotrophic keratopathy (NK) is a degenerative corneal condition resulting from corneal nerve injury. Current therapies, including the recombinant human nerve growth factor (rhNGF) therapy, requires continuous administration. This study aims to develop a novel and highly effective gene therapy strategy for the prevention and treatment of NK.

METHODS

Adeno-associated virus (AAV) was transduced into corneal stromal cells by intrastromal injection. Three dimensional corneal wholemount imaging with co-immunostaining of ZO-1 and tubulin was utilized to assess the transduction of AAV.rh10. The efficacy of prevention and treatment of NK by a single intrastromal injection of AAV-Ngf was tested using capsaicin mouse model, herpes simplex keratitis (HSK) model, type Ⅱ diabetes model and alkali burn model. rhNGF eye drops served as the positive control.

RESULTS

Intrastromal injection of AAV.rh10 efficiently transduced the subepithelial nerve plexus and retrogradely transported to the trigeminal ganglion (TG). A single injection of AAV.rh10-Ngf can significantly promote corneal nerve repair, accelerate corneal epithelial repair, reduce corneal stromal edema, and improve corneal sensitivity across the four NK models. The therapeutic effects were consistent with those achieved by continuous administration of rhNGF drops by 6 times daily.

CONCLUSIONS

This proof-of-concept study demonstrates that AAV.rh10-Ngf gene therapy is a promising method for preventing and treating of NK. Our results underline the potential for developing clinical trials to further explore the safety and efficacy of such gene therapy.

Recombinant human nerve growth factor (cenegermin) for moderate-to-severe dry eye: phase II, randomized, vehicle-controlled, dose-ranging trial

BACKGROUND

Dry eye disease (DED) includes neurosensory abnormalities as part of its multifactorial etiology. Nerve growth factor is important for maintaining corneal nerve integrity and wound healing. Cenegermin (recombinant human nerve growth factor) is a topical biologic that promotes corneal healing in patients with neurotrophic keratitis. The purpose of this study was to evaluate efficacy and safety of cenegermin in moderate-to-severe DED and identify an optimal dosing strategy.

METHODS

This was a phase II, multicenter, randomized, double-masked, vehicle-controlled, dose-ranging clinical trial in patients with moderate-to-severe DED, including Sjögren's DED (NCT03982368). Patients received 1 drop of cenegermin 3 times daily (t.i.d.; 20 mcg/mL), cenegermin 2 times daily (b.i.d.; 20 mcg/mL) and vehicle once daily, or vehicle t.i.d. for 4 weeks. Follow-up continued for 12 additional weeks. The primary endpoint was change in Schirmer I score from baseline to week 4. Other key endpoints included rate of responders (Schirmer I test > 10 mm/5 min) after treatment and change in Symptoms Assessment iN Dry Eye (SANDE) scores from baseline to end of follow-up. A 1-sided test (α = 0.025) was used to evaluate statistical significance.

RESULTS

At week 4, mean changes in Schirmer I scores were not statistically significantly different in either cenegermin group versus vehicle (cenegermin vs vehicle [treatment difference; 95% CI]: t.i.d., 2.60 mm and b.i.d., 3.99 mm vs 1.68 mm [t.i.d.: 0.93; -1.47 to 3.32, P = 0.078; b.i.d.: 2.31; -0.08 to 4.70, P = 0.066]). More patients responded to treatment with cenegermin t.i.d. and b.i.d. versus vehicle (t.i.d.: 25.9% [21/81, P = 0.028]; b.i.d.: 29.3% [24/82, P = 0.007] vs 11.9% [10/84]), with statistical significance (set at P < 0.025) observed in the b.i.d. group. Only cenegermin t.i.d. yielded statistically significant (P < 0.025) reductions in SANDE scores versus vehicle, which were sustained up to the end of follow-up (P value range, 0.002-0.008). Eye pain, primarily mild and transient, was the most frequently observed treatment-emergent adverse event with cenegermin. Similar results were observed in patients with Sjögren's DED.

CONCLUSIONS

Cenegermin was well tolerated and although this study did not meet its primary endpoint, significant improvement in patient-reported symptoms of dry eye was observed through follow-up. Larger studies evaluating cenegermin in patients with DED are warranted.

TRIAL REGISTRATION

NCT03982368; registered May 23, 2019.

Assessment of corneal nerve regeneration after axotomy in a compartmentalized microfluidic chip model with automated 3D high resolution live-imaging

Introduction

Damage to the corneal nerves can result in discomfort and chronic pain, profoundly impacting the quality of life of patients. Development of novel in vitro method is crucial to better understand corneal nerve regeneration and to find new treatments for the patients. Existing in vitro models often overlook the physiology of primary sensory neurons, for which the soma is separated from the nerve endings.

Methods

To overcome this limitation, our novel model combines a compartmentalized microfluidic culture of trigeminal ganglion neurons from adult mice with live-imaging and automated 3D image analysis offering robust way to assess axonal regrowth after axotomy.

Results

Physical axotomy performed by a two-second aspiration led to a reproducible 70% axonal loss and altered the phenotype of the neurons, increasing the number of substance P-positive neurons 72 h post-axotomy. To validate our new model, we investigated axonal regeneration after exposure to pharmacological compounds. We selected various targets known to enhance or inhibit axonal regrowth and analyzed their basal expression in trigeminal ganglion cells by scRNAseq. NGF/GDNF, insulin, and Dooku-1 (Piezo1 antagonist) enhanced regrowth by 81, 74 and 157%, respectively, while Yoda-1 (Piezo1 agonist) had no effect. Furthermore, SARM1-IN-2 (Sarm1 inhibitor) inhibited axonal regrowth, leading to only 6% regrowth after 72 h of exposure (versus 34% regrowth without any compound).

Discussion

Combining compartmentalized trigeminal neuronal culture with advanced imaging and analysis allowed a thorough evaluation of the extent of the axotomy and subsequent axonal regrowth. This innovative approach holds great promise for advancing our understanding of corneal nerve injuries and regeneration and ultimately improving the quality of life for patients suffering from sensory abnormalities, and related conditions.

Phase IV Multicenter, Prospective, Open-Label Clinical Trial of Cenegermin (rhNGF) for Stage 1 Neurotrophic Keratopathy (DEFENDO)

INTRODUCTION

Cenegermin is approved for treatment of neurotrophic keratopathy (NK) and has been studied in patients with stage 2 or 3 NK. This study evaluated the efficacy and safety of cenegermin in adults with stage 1 NK.

METHODS

This was a phase IV, multicenter, prospective, open-label, uncontrolled trial. Adults with stage 1 NK (Mackie criteria) and decreased corneal sensitivity (≤ 4 cm) received 1 drop of cenegermin 20 mcg/ml in the affected eye(s) 6 times/day for 8 weeks with a 24-week follow-up.

RESULTS

Of 37 patients, corneal epithelial healing was observed in 84.8% (95% confidence interval [CI] 68.1-94.9%; P < 0.001) at week 8; 95.2% (95% CI 76.2-99.9%; P < 0.001) of those patients remained healed at the end of the 24-week follow-up (week 32). At week 8, 91.2% (95% CI 76.3-98.1%; P < 0.001) of patients experienced improved corneal sensitivity; this improvement was observed in 82.1% (95% CI 63.1-93.9%; P < 0.001) of patients at week 32. Mean best-corrected distance visual acuity change from baseline at week 8 was - 0.10 logMAR (standard deviation [SD], 0.15; 95% CI - 0.16 to - 0.05; P < 0.001) and at week 32 was - 0.05 logMAR (SD, 0.16; 95% CI - 0.11 to 0.01; P = 0.122). At weeks 8 and 32, 15.2% (95% CI 5.1-31.9%; P < 0.001) and 10.7% (95% CI 2.3-28.2%; P < 0.001) of patients, respectively, had a 15-letter gain from baseline. At least one adverse event (AE) was reported by 73.0% and 45.7% of patients during the treatment and follow-up periods, respectively. The most common treatment-related, treatment-emergent AEs were eye pain (37.8%), blurred vision (10.8%), and eyelid pain (8.1%); these were mostly mild or moderate and were only reported during the treatment period.

CONCLUSIONS

These results support the potential use of cenegermin for treating patients with stage 1 NK, and future confirmatory studies would be beneficial to elaborate on these findings.

TRIAL REGISTRATION

DEFENDO; NCT04485546.