Differential effects of risuteganib and bevacizumab on AMD cybrid cells.

PURPOSE: Intravitreal injections of anti-vascular endothelial growth factor (VEGF) treatments are currently used to treat wet age-related macular degeneration (AMD), diabetic retinopathy, and macular edema. Chronic, repetitive treatments with anti-VEGF may have unintended consequences beyond the inhibition of angiogenesis. Most recently, clinical trials have been conducted with risuteganib (RSG, Luminate®), which is anti-angiogenic and has neuroprotective and anti-inflammatory properties. Mitochondrial damage and dysfunction play a major role in development of AMD. Transmitochondrial cybrids are cell lines established by fusing human retinal pigment epithelial (RPE) cells that are Rho0 (lacking mtDNA) with platelets isolated from AMD subjects or age-matched normal subjects. Cybrid cell lines have identical nuclei but mitochondria from different subjects, enabling investigation of the functional consequences of damaged AMD mitochondria. The present study compares the responses of AMD cybrids treated with bevacizumab (Bmab, Avastin®) versus risuteganib (RSG, Luminate®). METHODS: Cybrids were created by fusing mtDNA depleted ARPE-19 cells with platelets from AMD or age-matched normal patients. AMD (n = 5) and normal (n = 3) cybrids were treated for 48 h with or without 1x clinical dose of 1.25 mg/50 µl (25,000 µg/ml) of Bmab or 1.0 mg/50 µl (20,000 µg/ml) of RSG. Cultures were analyzed for levels of cleaved caspase 3/7 and NucLight Rapid Red staining (IncuCyte® Live Cell Imager), mitochondrial membrane potential (ΔΨm, JC1 assay) or reactive oxygen species (ROS, H2DCFDA assay). Expression levels of genes related to the following pathways were analyzed with qRT-PCR: Apoptosis (BAX, BCL2L13, CASP-3, -7, -9); angiogenesis (VEGFA, HIF1α, PDGF); integrins (ITGB-1, -3, -5, ITGA-3, -5, -V); mitochondrial biogenesis (PGC1α, POLG); oxidative stress (SOD2, GPX3, NOX4); inflammation (IL-6, -18, -1ß, IFN-ß1); and signaling (P3KCA, PI3KR1). Statistical analyses were performed using GraphPad Prism software. RESULTS: The untreated AMD cybrids had significantly higher levels of cleaved caspase 3/7 compared to the untreated normal cybrids. The Bmab-treated AMD cybrids showed elevated levels of cleaved caspase 3/7 compared to untreated AMD or RSG-treated AMD cybrids. The Bmab-treated cybrids had lower ΔΨm compared to untreated AMD or RSG-treated AMD cybrids. The ROS levels were not changed with Bmab or RSG treatment. Results showed that Bmab-treated cybrids had higher expression levels of inflammatory (IL-6, IL1-ß), oxidative stress (NOX4) and angiogenesis (VEGFA) genes compared to untreated AMD, while RSG-treated cybrids had lower expression levels of apoptosis (BAX), angiogenesis (VEGFA) and integrin (ITGB1) genes. CONCLUSIONS: These data suggest that the mechanism(s) of action of RSG, an integrin regulator, and Bmab, a recombinant monoclonal antibody, affect the AMD RPE cybrid cells differently, with the former having more anti-apoptosis properties, which may be desirable in treating degenerative ocular diseases.

The Transcriptome Profile of Retinal Pigment Epithelium and Müller Cell Lines Protected by Risuteganib Against Hydrogen Peroxide Stress.

Purpose: Oxidative stress contributes to the pathogenesis of vision-impairing diseases. In the retina, retinal pigment epithelium (RPE) and Müller cells support neuronal homeostasis, but also contribute to pathological development under stressed conditions. Recent studies found that the investigational drug risuteganib (RSG) has a good safety profile, provided protection in experimental models, and improved visual acuity in patients. The present in vitro study evaluated the effects of RSG in RPE and Müller cell lines stressed with the oxidant hydrogen peroxide (H2O2). Methods: Human RPE (ARPE-19) and Müller (MIO-M1) cell lines were treated with various combinations of RSG and H2O2. Trypan blue assay was used to investigate the effect of compounds on cell viability. Gene expression was measured using RNA sequencing to identify regulated genes and the biological processes and pathways involved. Results: Trypan blue assay found RSG pre-treatment significantly protected against H2O2-induced cell death in ARPE-19 and MIO-M1 cells. Transcriptome analysis found H2O2 regulated genes in several disease-relevant biological processes, including cell adhesion, migration, death, and proliferation; ECM organization; angiogenesis; metabolism; and immune system processes. RSG pre-treatment modulated these gene expression profiles in the opposite direction of H2O2. Pathway analysis found genes in integrin, AP-1, and syndecan signaling pathways were regulated. Expression of selected RSG-regulated genes was validated using qRT-PCR. Conclusions: RSG protected cultured human RPE and Müller cell lines against H2O2-induced cell death and mitigated the associated transcriptome changes in biological processes and pathways relevant to the pathogenesis of retinal diseases. These results demonstrate RSG reduced oxidative stress-induced toxicity in two retinal cell lines with potential relevance to the treatment of human diseases.

Impact of Baseline Quantitative OCT Features on Response to Risuteganib for the Treatment of Dry Age-Related Macular Degeneration: The Importance of Outer Retinal Integrity.

OBJECTIVE: The purpose of the study was to perform a post hoc analysis to explore the effect of baseline anatomic characteristics identified on OCT on best-corrected visual acuity (BCVA) responses to risuteganib from the completed phase II study in subjects with dry age-related macular degeneration (AMD). DESIGN: Post hoc analysis of a randomized, double-masked, placebo-controlled, phase II study. SUBJECTS: Eyes with intermediate dry AMD with BCVA between 20/40 and 20/200. Patients with concurrent vision-influencing or macula-obscuring ocular pathologies were excluded. METHODS: Patients were randomized to receive a 1-mg intravitreal risuteganib injection or a sham injection at baseline. A second 1-mg intravitreal injection of risuteganib was given at week 16 to those in the treatment arm. Two independent, masked reading centers evaluated the baseline anatomic characteristics on OCT to explore features associated with positive responses to risuteganib. MAIN OUTCOME MEASURES: Treatment response was defined as a gain of ≥ 8 letters in BCVA from baseline to week 28 in the treatment arm, compared with baseline to week 12 in the sham group. Anatomic parameters, measured by retinal segmentation platforms, including measures of retinal thickness were compared between the responders and nonresponders to risuteganib. RESULTS: Thirty-nine patients completed the study and underwent analysis. In the treatment arm, 48% of eyes demonstrated treatment responses, compared with 7% in the sham group. In the quantitative anatomic assessment, enhanced ellipsoid integrity, greater outer retinal thickness, and decreased geographic atrophy were associated with increased BCVA gains to risuteganib. CONCLUSIONS: This post hoc analysis demonstrated that baseline OCT features may help determine the likelihood of a functional response to risuteganib. The characterization of higher-order OCT features may provide important information regarding biomarkers for treatment response and could facilitate optimized clinical trial enrollment and enrichment.

Color Vision and Microperimetry Changes in Nonexudative Age-Related Macular Degeneration After Risuteganib Treatment: Exploratory Endpoints in a Multicenter Phase 2a Double-Masked, Randomized, Sham-Controlled, Crossover Clinical Trial.

BACKGROUND AND OBJECTIVE: To explore the association between best-corrected visual acuity (BCVA) improvement and changes in microperimetry (MP) and color vision in patients with nonexudative age-related macular degeneration following administration of two 1.0-mg intravitreal doses of risuteganib. PATIENTS AND METHODS: In a phase 2a, prospective, double-masked, sham-controlled study, eyes with nonexudative age-related macular degeneration and Early Treatment Diabetic Retinopathy Study BCVA between 20/40 and 20/200 were randomized to intravitreal risuteganib (1.0 mg) or sham injection. The risuteganib group received a second 1.0-mg dose, and patients in the sham group crossed over to receive 1.0 mg of risuteganib at week 16. Exploratory endpoints included changes in color vision and mesopic MP. RESULTS: Thirty-nine patients (risuteganib, n = 25; sham, n = 14) completed the study. There was a significant (P < .05) correlation between BCVA and the total error score (TES) for both Lanthony and Hue Style. Confusion index was close to the criterion for significance (P = .056) in the risuteganib group. All color vision metrics demonstrated a trend toward improvement in risuteganib responders (BCVA letter gain ≥8 letters) and no change in the nonresponders, with significant differences seen in confusion index between the risuteganib and control group (P = .0493) and between responders and nonresponders (P = .0478). MP showed that risuteganib responders improved in mean sensitivity and change in number of loci ≤11 dB and ≤0 dB, whereas nonresponders worsened. CONCLUSION: All color vision and MP parameters tested trended toward improvement in risuteganib-treated patients and risuteganib responders. Statistically significant improvement was evident in two metrics: confusion index (in risuteganib-treated patients and responders) and number of loci with decreased sensitivity (in responders). A significant correlation between BCVA and both TES Lanthony and TES Hue Style in risuteganib patients provides concurrent evidence of objective and subjective improvement of retinal function. [Ophthalmic Surg Lasers Imaging Retina 2022;53:430-438.].

Safety and Efficacy of Intravitreal Risuteganib for Non-Exudative AMD: A Multicenter, Phase 2a, Randomized, Clinical Trial.

BACKGROUND AND OBJECTIVE: To evaluate the safety and efficacy of 1.0 mg risuteganib in subjects with nonexudative age-related macular degeneration (AMD). PATIENTS AND METHODS: This was a phase 2a, prospective, double-masked, sham-controlled study. Eyes with nonexudative (dry) AMD and Early Treatment Diabetic Retinopathy Study (ETDRS) best-corrected visual acuity (BCVA) between 20/40 and 20/200 were included. Subjects were randomized to intravitreal 1.0 mg risuteganib or sham injection. At Week 16, subjects in the risuteganib group received a second 1.0-mg dose and the sham group crossed over to receive a dose of 1.0 mg risuteganib and were evaluated at Week 28. The primary endpoint was proportion of subjects with 8 letters ETDRS or more BCVA gain from baseline to Week 28 in the risuteganib group versus baseline to Week 12 for the sham group. BCVA was tested and subjects were observed for adverse events (AEs) every 4 weeks until completion of the study at 32 weeks. RESULTS: Forty-five subjects (risuteganib, n = 29; sham, n = 16) were enrolled in the study, of whom 39 (risuteganib, n = 25; sham, n = 14) completed the study and were included in the per protocol efficacy analysis. At baseline, mean age was 78.8 and 75.9 years and mean BCVA was 67.1 and 64.4 letters in the sham and risuteganib groups, respectively. The primary endpoint was met by 48% of the risuteganib group at Week 28 and 7% of the sham group at Week 12 (P = .013). Of the risuteganib subjects, 20% gained 15 letters or more at Week 28, whereas no patients in the sham group at Week 12 achieved this visual acuity gain. The only ocular treatment-related treatment-emergent AE was vitreous floaters, which spontaneously recovered without sequelae. No drug-related serious AE was reported. CONCLUSIONS: Risuteganib demonstrated significant BCVA improvement in patients with non-exudative AMD. No drug-related AEs were seen during a 32-week observation period. [Ophthalmic Surg Lasers Imaging Retina. 2021;52:327-335.].

Risuteganib Protects against Hydroquinone-induced Injury in Human RPE Cells.

Purpose: Cigarette smoking has been implicated in the pathogenesis of AMD. Integrin dysfunctions have been associated with AMD. Herein, we investigate the effect of risuteganib (RSG), an integrin regulator, on RPE cell injury induced by hydroquinone (HQ), an important oxidant in cigarette smoke. Methods: Cultured human RPE cells were treated with HQ in the presence or absence of RSG. Cell death, mitochondrial respiration, reactive oxygen species production, and mitochondrial membrane potential were measured by flow cytometry, XFe24 analyzer, and fluorescence plate reader, respectively. Whole transcriptome analysis and gene expression were analyzed by Illumina RNA sequencing and quantitative PCR, respectively. F-actin aggregation was visualized with phalloidin. Levels of heme oxygenase-1, P38, and heat shock protein 27 proteins were measured by Western blot. Results: HQ induced necrosis and apoptosis, decreased mitochondrial bioenergetics, increased reactive oxygen species levels, decreased mitochondrial membrane potential, increased F-actin aggregates, and induced phosphorylation of P38 and heat shock protein 27. HQ, but not RSG alone, induced substantial transcriptome changes that were regulated by RSG cotreatment. RSG cotreatment significantly protected against HQ-induced necrosis and apoptosis, prevented HQ-reduced mitochondrial bioenergetics, decreased HQ-induced reactive oxygen species production, improved HQ-disrupted mitochondrial membrane potential, reduced F-actin aggregates, decreased phosphorylation of P38 and heat shock protein 27, and further upregulated HQ-induced heme oxygenase-1 protein levels. Conclusions: RSG has no detectable adverse effects on healthy RPE cells, whereas RSG cotreatment protects against HQ-induced injury, mitochondrial dysfunction, and actin reorganization, suggesting a potential role for RSG therapy to treat retinal diseases such as AMD.

Watertight cataract incision closure using fibrin tissue adhesive.

PURPOSE: To determine whether a simple method for applying fibrin tissue adhesive to a clear corneal cataract incision can create a watertight seal. SETTING: Laboratory investigation. METHODS: Clear corneal cataract incisions were simulated in 8 eye-bank eyes. In 4 eyes, fibrin adhesive was applied to the incision in a simple manner; the other 4 eyes were controls with no adhesive. Each eye was tested under low pressure conditions to detect fluid ingress of India Ink on the eye's surface. The eyes were tested again with external compression to distort the incision to detect fluid egress. RESULTS: In the eyes with fibrin adhesive, there was no egress of fluid with incision distortion and no ingress of India Ink. In the 4 eyes without adhesive, there was ingress and egress of fluid. CONCLUSION: A simple method of applying fibrin adhesive to cataract incisions created a watertight seal.