Species differences in ocular pharmacokinetics and pharmacological activities of regorafenib and pazopanib eye-drops among rats, rabbits and monkeys

QbD-Based Development and Evaluation of Pazopanib Hydrochloride Extrudates Prepared by Hot-Melt Extrusion Technique: In Vitro and In Vivo Evaluation

BACKGROUND

Pazopanib hydrochloride (PZB) is a protein kinase inhibitor approved by the United States Food and Drug Administration and European agencies for the treatment of renal cell carcinoma and other renal malignancies. However, it exhibits poor aqueous solubility and inconsistent oral drug absorption. In this regard, the current research work entails the development and evaluation of the extrudates of pazopanib hydrochloride by the hot-melt extrusion (HME) technique for solubility enhancement and augmenting oral bioavailability.

RESULTS

Solid dispersion of the drug was prepared using polymers such as Kollidon VA64, hydroxypropylmethylcellulose (HPMC), Eudragit EPO, and Affinisol 15LV in a 1:2 ratio by the HME process through a lab-scale 18 mm extruder. Systematic optimization of the formulation variables was carried out with the help of custom screening design (JMP Software by SAS, Version 14.0) to study the impact of polymer type and plasticizer level on the quality of extrudate processability by measuring the torque value, appearance, and disintegration time as the responses. The polymer blends containing Kollidon VA64 and Affinisol 15LV resulted in respective clear transparent extrudates, while Eudragit EPO and HPMC extrudates were found to be opaque white and brownish, respectively. Furthermore, evaluation of the impact of process parameters such as screw rpm and barrel temperature was measured using a definitive screening design on the extrude appearance, torque, disintegration time, and dissolution profile. Based on the statistical outcomes, it can be concluded that barrel temperature has a significant impact on torque, disintegration time, and dissolution at 30 min, while screw speed has an insignificant impact on the response variables. Affinisol extrudates showed less moisture uptake and faster dissolution in comparison to Kollidon VA64 extrudates. Affinisol extrudates were evaluated for polymorphic stability up to a 3-month accelerated condition and found no recrystallization. PZB-Extrudates using the Affinisol polymer (Test formulation A) revealed significantly higher bioavailability (AUC) in comparison to the free Pazopanib drug and marketed formulation.

Eye Drop with Fas-Blocking Peptide Attenuates Age-Related Macular Degeneration

Age-related macular degeneration (AMD), characterized by macular retinal degeneration, poses a significant health concern due to the lack of effective treatments for prevalent dry AMD. The progression of AMD is closely linked to reactive oxygen species and Fas signaling, emphasizing the need for targeted interventions. In this study, we utilized a NaIO3-induced retinal degeneration mouse model to assess the efficacy of Fas-blocking peptide (FBP). Intravitreal administration of FBP successfully suppressed Fas-mediated inflammation and apoptosis, effectively arresting AMD progression in mice. We developed a 6R-conjugated FBP (6R-FBP) for eye drop administration. 6R-FBP, administered as an eye drop, reached the retinal region, attenuating degeneration by modulating the expression of inflammatory cytokines and blocking Fas-mediated apoptosis in rodent and rabbit NaIO3-induced retinal degeneration models to address practical concerns. Intravitreal FBP and 6R-FBP eye drops effectively reduced retinal degeneration and improved retinal thickness in rodent and rabbit models. This study highlights the therapeutic potential of FBP, particularly 6R-FBP as an eye drop, in inhibiting Fas-mediated cell signaling and protecting against retinal cell death and inflammation in dry AMD. Future investigations should explore the translational prospects of this approach in primates with eye structures comparable to those of humans.

Ocular and Plasma Pharmacokinetics of Enavogliflozin Ophthalmic Solution in Preclinical Species

An enavogliflozin ophthalmic solution (DWRX2008) is being developed to treat diabetic retinopathy and macular edema. This study evaluated the ocular distribution and plasma pharmacokinetics (PKs) of enavogliflozin in animal species. A sample of [14C] enavogliflozin was ocularly administered to two rabbits per time point at single doses of 600 μg/eye to evaluate ocular PK, which was evaluated using autoradiography until 48 h post-dose. Plasma concentrations after ocular administration in six rabbits, three rats, and three beagle dogs with single doses of 400 μg, 25 μg, and 100 μg, respectively, were investigated for 24 h. The retinal concentration of [14C] enavogliflozin reached Cmax at 2.0 h with an elimination half-life of 32.5 h, which remained above the IC50 value of sodium-dependent glucose transporter 2 until 24 h post-dose. In the plasma of rabbits, the fastest Tmax of 0.5 h and a 3.6 h half-life were observed among animal species. The relative bioavailability in rabbits after ocular administration was 3.4 compared to oral administration. Ocular administration of enavogliflozin could be a potential therapeutic route for diabetic retinal complications, based on relative bioavailability and effective delivery to the posterior ocular segment. DWRX2008 would be applicable to humans with favorable PK profiles and minimal systemic adverse effect.

A review of emerging tyrosine kinase inhibitors as durable treatment of neovascular age-related macular degeneration

INTRODUCTION

Current treatment for age-related macular degeneration poses a large burden on patients and the inability of patients to adhere to this immense burden can lead to worse visual outcomes. Novel treatments have been proposed to extend treatment intervals and reduce visit burden.

AREAS COVERED

This review article summarizes phase I and phase II clinical trials of tyrosine kinase inhibitors as durable treatment options for patient with neovascular age-related macular degeneration.

EXPERT OPINION

Tyrosine kinase inhibitors have shown substantial promise in reducing treatment burden while maintaining visual acuity and anatomic outcomes with favorable safety profiles. Several platforms have shown positive outcomes in initial trials and are currently moving toward phase III clinical trials.

A new era in posterior segment ocular drug delivery: Translation of systemic, cell-targeted, dendrimer-based therapies

Vision impairment and loss due to posterior segment ocular disorders, including age-related macular degeneration and diabetic retinopathy, are a rapidly growing cause of disability globally. Current treatments consist primarily of intravitreal injections aimed at preventing disease progression and characterized by high cost and repeated clinic visits. Nanotechnology provides a promising platform for drug delivery to the eye, with potential to overcome anatomical and physiological barriers to provide safe, effective, and sustained treatment modalities. However, there are few nanomedicines approved for posterior segment disorders, and fewer that target specific cells or that are compatible with systemic administration. Targeting cell types that mediate these disorders via systemic administration may unlock transformative opportunities for nanomedicine and significantly improve patient access, acceptability, and outcomes. We highlight the development of hydroxyl polyamidoamine dendrimer-based therapeutics that demonstrate ligand-free cell targeting via systemic administration and are under clinical investigation for treatment of wet age-related macular degeneration.

Research progress of VEGFR small molecule inhibitors in ocular neovascular diseases

Angiogenesis is the biological process in which existing blood vessels generate new ones and it is essential for body growth and development, wound healing, and granulation tissue formation. Vascular endothelial growth factor receptor (VEGFR) is a crucial cell membrane receptor that binds to VEGF to regulate angiogenesis and maintenance. Dysregulation of VEGFR signaling can lead to several diseases, such as cancer and ocular neovascular disease, making it a crucial research area for disease treatment. Currently, anti-VEGF drugs commonly used in ophthalmology are mainly four macromolecular drugs, Bevacizumab, Ranibizumab, Conbercept and Aflibercept. Although these drugs are relatively effective in treating ocular neovascular diseases, their macromolecular properties, strong hydrophilicity, and poor blood-eye barrier penetration limit their efficacy. However, VEGFR small molecule inhibitors possess high cell permeability and selectivity, allowing them to traverse and bind to VEGF-A specifically. Consequently, they have a shorter duration of action on the target, and they offer significant therapeutic benefits to patients in the short term. Consequently, there is a need to develop small molecule inhibitors of VEGFR to target ocular neovascularization diseases. This review summarizes the recent developments in potential VEGFR small molecule inhibitors for the targeted treatment of ocular neovascularization diseases, with the aim of providing insights for future studies on VEGFR small molecule inhibitors.

Topical Treatment for Retinal Degenerative Pathologies: A Systematic Review

The topical administration of medicines is the preferred route in ocular therapy, at least for the anterior segment of the eye. However, the eye's inherent functional and biological barriers all work against the active pharmaceutical ingredient (API) to efficiently reach the targeted retinal structures. The main objective of this article is to offer a systematic review of the scientific literature in recent years, focusing on the latest developments of topical treatment intended for retinal degenerative diseases. Database search returned 102 clinical studies, focused on topical treatment for age macular degeneration, macular edemas (in diabetic retinopathy, surgery related or in retinal dystrophies) or glaucoma. After the exclusion of low-powered studies and those combining vitreo-retinal surgery, 35 articles remained for analysis. Currently, the topical treatment of retinal degenerative diseases is limited by the difficulty to deliver effective drug concentrations to the posterior eye structures. However, in the case of drug classes like NSAIDs, the presence of certain molecular and metabolic features for specific representatives makes the topical administration currently feasible in several clinical contexts. For other drug classes, either a fine-tuning of the API's pharmacokinetic profile or the use of more advanced formulation strategies, such as rationally designed nanostructured drugs and vehicles, crystalline polymorphs or supramolecular complexes, could bring the much awaited breakthrough for a more predictable and controlled delivery towards the retinal structures and could eventually be employed in the future for the development of more effective ways of delivering drugs to the posterior eye, with the ultimate goal of improving their clinical efficacy.

Topical Drug Delivery to the Posterior Segment of the Eye

Topical drug delivery to the posterior segment of the eye is a very complex challenge. However, topical delivery is highly desired, to achieve an easy-to-use treatment option for retinal diseases. In this review, we focus on the drug characteristics that are relevant to succeed in this challenge. An overview on the ocular barriers that need to be overcome and some relevant animal models to study ocular pharmacokinetics are given. Furthermore, a summary of substances that were able to reach the posterior segment after eye drop application is provided, as well as an outline of investigated delivery systems to improve ocular drug delivery. Some promising results of substances delivered to the retina suggest that topical treatment of retinal diseases might be possible in the future, which warrants further research.

Patient preferences in retinal drug delivery

Retinal vascular diseases (RVDs) are often treated with intravitreally (IVT) injected drugs, with relatively low patient compliance and potential risks. Ongoing research explores alternative RVD treatments, including eye drops and oral tablets. This study surveyed RVD patients treated with IVT injections to establish factors influencing low compliance rates while gauging treatment delivery method preferences. Demographics, perspectives, and treatment preferences were collected via IRB-approved, self-administered survey sent to Glick Eye Institute patients treated via IVT injections. Demographics, diagnoses, and treatments were ascertained from respondents’ medical records. Gender, age, and number of IVT injections received were used as stratifications. Five-level Likert-style scales and t-tests evaluated responses and stratification comparisons. The most common diagnoses in the respondent population (n = 54; response rate = 5%) were age-related macular degeneration, macular edema, and diabetic retinopathy. Respondents had varying levels of education, income, and age. Most (83%) admitted feeling anxious prior to their first IVT injection, but 80% reported willingness to receive IVT injections indefinitely, with a preference for ophthalmologist visits every 1–3 months. Eye drops would be preferred over IVT injections by 76% of respondents, while 65% preferred oral tablets, due to several perceived negative factors of IVT injections and positive factors for eye drops. Stratified groups did not differ in responses to survey questions. RVD patients will accept IVT injections for vision preservation, but alternative delivery methods like eye drops or oral tablets would be preferred. Thus, development of eye drop and oral therapeutics for RVD treatment is further emphasized by these findings.

The Emerging Role of Topical Ocular Drugs to Target the Posterior Eye

The prevalence of chronic fundus diseases is increasing with the aging of the general population. The treatment of these intraocular diseases relies on invasive drug delivery because of the globular structure and multiple barriers of the eye. Frequent intraocular injections bring heavy burdens to the medical care system and patients. The use of topical drugs to treat retinal diseases has always been an attractive solution. The fast development of new materials and technologies brings the possibility to develop innovative topical formulations. This article reviews anatomical and physiological barriers of the eye which affect the bioavailability of topical drugs. In addition, we summarize innovative topical formulations which enhance the permeability of drugs through the ocular surface and/or extend the drug retention time in the eye. This article also reviews the differences of eyes between different laboratory animals to address the translational challenges of preclinical models. The fast development of in vitro eye models may provide more tools to increase the clinical translationality of topical formulations for intraocular diseases. Clinical successes of topical formulations rely on continuous and collaborative efforts between different disciplines.

A novel method of screening combinations of angiostatics identifies bevacizumab and temsirolimus as synergistic inhibitors of glioma-induced angiogenesis

Tumor angiogenesis is critical for the growth and progression of cancer. As such, angiostasis is a treatment modality for cancer with potential utility for multiple types of cancer and fewer side effects. However, clinical success of angiostatic monotherapies has been moderate, at best, causing angiostatic treatments to lose their early luster. Previous studies demonstrated compensatory mechanisms that drive tumor vascularization despite the use of angiostatic monotherapies, as well as the potential for combination angiostatic therapies to overcome these compensatory mechanisms. We screened clinically approved angiostatics to identify specific combinations that confer potent inhibition of tumor-induced angiogenesis. We used a novel modification of the ex ovo chick chorioallantoic membrane (CAM) model that combined confocal and automated analyses to quantify tumor angiogenesis induced by glioblastoma tumor onplants. This model is advantageous due to its low cost and moderate throughput capabilities, while maintaining complex in vivo cellular interactions that are difficult to replicate in vitro. After screening multiple combinations, we determined that glioblastoma-induced angiogenesis was significantly reduced using a combination of bevacizumab (Avastin®) and temsirolimus (Torisel®) at doses below those where neither monotherapy demonstrated activity. These preliminary results were verified extensively, with this combination therapy effective even at concentrations further reduced 10-fold with a CI value of 2.42E-5, demonstrating high levels of synergy. Thus, combining bevacizumab and temsirolimus has great potential to increase the efficacy of angiostatic therapy and lower required dosing for improved clinical success and reduced side effects in glioblastoma patients.

The Role of Eph Receptors and Ephrins in Corneal Physiology and Diseases

The cornea, while appearing to be simple tissue, is actually an extremely complex structure. In order for it to retain its biomechanical and optical properties, perfect organization of its cells is essential. Proper regeneration is especially important after injuries and in the course of various diseases. Eph receptors and ephrin are mainly responsible for the proper organization of tissues as well as cell migration and communication. In this review, we present the current state of knowledge on the role of Eph and ephrins in corneal physiology and diseases, in particular, we focused on the functions of the epithelium and endothelium. Since the role of Eph and ephrins in the angiogenesis process has been well established, we also analyzed their influence on conditions with corneal neovascularization.

Gelling hypotonic polymer solution for extended topical drug delivery to the eye

Eye-drop formulations should hold as high a concentration of soluble drug in contact with ocular epithelium for as long as possible. However, eye tears and frequent blinking limit drug retention on the ocular surface, and gelling drops typically form clumps that blur vision. Here, we describe a gelling hypotonic solution containing a low concentration of a thermosensitive triblock copolymer, for extended ocular drug delivery. On topical application, the hypotonic formulation forms a highly uniform and clear thin layer that conforms to the ocular surface and resists clearance from blinking, significantly increasing the intraocular absorption of hydrophilic and hydrophobic drugs and extending the drug–ocular-epithelium contact time with respect to conventional thermosensitive gelling formulations and commercial eye drops. We also show that the conformal gel layer allows for therapeutically relevant drug delivery to the eyeball’s posterior segment in pigs. Our findings highlight the importance of formulations that conform to the ocular surface prior to viscosity enhancement, for increased and prolonged ocular-surface contact and drug absorption.

Effects of Regorafenib, a Multi-Kinase Inhibitor, on Conjunctival Scarring in a Canine Filtration Surgery Model in Comparison with Mitomycin-C

Regorafenib eye drops were developed for treating age-related macular degeneration. This study aimed to investigate the effects of this multi-kinase inhibitor on intraocular pressure (IOP), bleb formation, and conjunctival changes in a canine filtration surgery model. Glaucoma filtration surgery models were created in 24 eyes of 24 beagles. In experiment 1 (Ex 1), regorafenib eye drops (regorafenib group: n = 6) or a vehicle (control group, n = 6) were instilled twice daily for 4 weeks postoperatively. In experiment 2 (Ex 2), regorafenib eye drops were instilled as in Ex 1 (regorafenib group: n = 6) for 12 weeks while conventional intraoperative mitomycin-C (MMC) was utilized (MMC group: n = 6), In Ex 1, only the regorafenib group showed significant IOP reduction with a significantly higher bleb score. Subconjunctival area, collagen density, vessels, and cells showing proliferation and differentiation were lower in subconjunctival tissue in the regorafenib group. In Ex 2, no significant difference was found in IOP reduction and bleb formation between the regorafenib and MMC groups; bleb walls were significantly thicker and collagen density and vessels were higher in the regorafenib group; and no differences were observed in the above-mentioned cells. Thus, regorafenib might be a better alternative to MMC for creating thicker and less ischemic blebs in glaucoma filtration surgery.