Evaluation of Long-Lasting Potential of Suprachoroidal Axitinib Suspension Via Ocular and Systemic Disposition in Rabbits

Beyond the injection: delivery systems reshaping retinal disease management

INTRODUCTION

Intravitreal injections remain the standard for treating common retinal diseases including age-related macular degeneration (AMD), diabetic macular edema (DME) and diabetic retinopathy. However, frequent administration creates significant treatment burden due to limited drug half-life and the chronic nature of these conditions.

AREAS COVERED

This review summarizes emerging drug delivery techniques and therapies for retinal disease that have achieved FDA approval within the past five years or have advanced to Phase 3 development, including intravitreal sustained-release platforms and alternative delivery routes (suprachoroidal, subretinal, topical, and subcutaneous). Specific innovations discussed include the ranibizumab port delivery system, EYP-1901 (Duravyu, vorolanib implant), KSI-301 (tarcocimab tedromer), KSI-501, OTX-TKI (Axpaxli, axitinib implant), 4D-150, revakinagene taroretcel-lwey (Encelto, NT-501, encapsulated cell therapy), Xipere (triamcinolone acetonide injectable suspension), AU-011 (belzupacap sarotalocan targeted delivery), ABBV-RGX-314, elamipretide, and OCS-01 (high concentration dexamethasone).

EXPERT OPINION

Promising innovations include sustained-release intravitreal implants, topical and subcutaneous delivery systems, and targeted methods like suprachoroidal and subretinal injections, each with unique advantages and limitations. Challenges include overcoming the blood-retinal barrier, surgical complications with implantable devices, and ensuring patient adherence. Advances in smart delivery systems, drug formulations, and predictive models, alongside interdisciplinary collaboration, will be crucial in achieving personalized, effective, and sustainable retinal therapies.

Suprachoroidal Drug Delivery for VEGF Suppression in Wet AMD and Other Diseases With Choroidal Neovascularization

PURPOSE

Choroidal neovascularization caused by age-related macular degeneration, among other diseases, causes significant visual impairment. Intravitreal therapeutics inhibiting vascular endothelial growth factor (VEGF) signaling have shown excellent safety and efficacy in regressing choroidal neovascularization and improving vision. Current US Food and Drug Administration (FDA)-approved treatments deliver these drugs into the vitreous cavity, even though choroidal neovascularization originates from aberrant signaling in the choroid.

DESIGN

Systematic review.

METHODS

A literature search was conducted across PubMed and Google Scholar from inception up to December 31, 2024, focusing on studies investigating suprachoroidal delivery of anti-VEGF therapy. Randomized controlled trials, cohort studies, and case-control studies were included, whereas case reports and review articles were excluded.

RESULTS

A total of 15 peer-reviewed articles, 3 press releases, 6 conference abstracts and presentations, and 8 clinical trials were identified that were relevant to the topic of suprachoroidal delivery of anti-VEGF therapy.

CONCLUSIONS

The suprachoroidal space is a potential space between the sclera and the choroid, which has recently become a route of delivery in an FDA-approved treatment. Notably, suprachoroidal delivery results in higher choroidal drug concentrations than intravitreal delivery. Promising results thus far have been seen with suprachoroidal delivery of VEGF-targeting therapies in clinical and preclinical studies; however, future work is needed to more fully demonstrate safety and efficacy.

Development of axitinib-loaded polymeric ocular implants for the treatment of posterior ocular diseases

Diabetic retinopathy (DR) and age-related macular degeneration (AMD) are the primary causes of vision impairment and blindness worldwide. The current treatment for these diseases is an intravitreal injection of anti-VEGF agents, which are costly and require frequent injections. Implants can be used to sustain the release of drugs and minimize side effects. Axitinib (AX) is a potent VEGF receptor inhibitor and a promising candidate for treating posterior ocular diseases, such as diabetic retinopathy (DR) and age-related macular degeneration (AMD). A sustained release of AX was successfully achieved from 3D-printed AX-loaded implants fabricated using the well-known 3D printing technique, semi-solid extrusion (SSE). AX at concentrations of 10% w/w and 20% w/w was incorporated within the polycaprolactone (PCL) and Precirol®-based matrix. The fabricated implants were characterized via FTIR spectroscopy, SEM imaging, and thermal analysis. The implants were also evaluated for their drug release and biocompatibility. The AX-loaded implants exhibited thermal stability, and no chemical interactions were found between AX and the matrix components. The release mechanism study of AX revealed that the concentration of drug loading influenced AX release from the implant, with a 10% w/w and 20 %w/w of AX showing first-order and Korsmeyer-Peppas mechanism, respectively. A biocompatibility study using ARPE-19 cells confirmed that AX-loaded implants are nontoxic and safe for ocular use.

Safety and Tolerability of Suprachoroidal Axitinib Injectable Suspension, for Neovascular Age-related Macular Degeneration; Phase I/IIa Open-Label, Dose-Escalation Trial

Purpose

To evaluate the safety and tolerability of a single dose of axitinib injectable suspension (CLS-AX), a pan-anti-VEGF tyrosine kinase inhibitor (TKI), administered via suprachoroidal injection in patients with neovascular age-related macular degeneration (nAMD).

Design

Phase I/IIa, open-label, sequential dose escalation.

Participants

Anti-VEGF treatment-experienced patients with active subfoveal choroidal neovascularization secondary to nAMD.

Methods

The study included 4 cohorts (0.03, 0.10, 0.50, and 1.0 mg) of approximately 5 patients each enrolled in a dose-escalating fashion. Enrolled patients received intravitreal aflibercept (2 mg) followed by a single unilateral dose of CLS-AX 1 month later. All patients were followed monthly for 3 months with the option of an additional 3 months of extended follow-up for cohorts 2 to 4. End points included systemic and ocular safety and tolerability, visual acuity, retinal thickness, and need for aflibercept therapy.

Main Outcome Measures

The number of patients reporting treatment-emergent adverse events (TEAEs) and serious adverse events (SAEs), changes in ophthalmic examinations, and the number of patients qualifying for additional therapy for nAMD based on protocol-defined criteria.

Results

OASIS enrolled 27 patients with nAMD with mean age of 81 years, mean duration of nAMD diagnosis of 54 months, and between 5 and 90 prior anti-VEGF treatments. Twenty-six patients completed through 3 months, with 14 entering and completing the 3-month extension. No SAEs, drug-related TEAEs, or TEAEs leading to discontinuation were observed after CLS-AX administration; there were no adverse events related to ocular inflammation, vasculitis, intraocular pressure, or dispersion of drug into the vitreous or anterior chamber. Through 6 months, stable mean best-corrected visual acuity and stable mean central subfield thickness (CST) were observed, suggestive of TKI biologic effect. No aflibercept therapy was administered up to 3 months in 58% (15/26) of patients who completed 3 months of follow-up in OASIS. In the Extension, 57% (8/14) of patients went up to 6 months without receiving aflibercept therapy.

Conclusions

Up to 1.0 mg CLS-AX, a highly potent TKI targeted to the suprachoroidal space (SCS) via the SCS Microinjector, was well tolerated, with stable mean visual acuity and mean CST. A majority of patients followed for 6 months did not require aflibercept therapy.

Financial Disclosures

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Long-acting delivery and therapies for neovascular age-related macular degeneration

INTRODUCTION

Neovascular age-related macular degeneration (nAMD) represents a leading cause of severe visual impairment in individuals over 50 years of age in developed nations. Intravitreal anti-vascular endothelial growth factor (VEGF) injections have become the standard of care for treating nAMD; however, monthly or bimonthly dosing represents significant time and cost burden due to the disease's chronic nature and limited medication half-life.

AREAS COVERED

This review summarizes innovative therapeutics and delivery methods for nAMD. Emerging methods for extended drug delivery include high molar concentration anti-VEGF drugs, intravitreal sustained-release polymers and devices, reservoirs for intravitreal delivery, suprachoroidal delivery of small molecular suspensions and gene therapy biofactories. In addition to VEGF-A, therapies targeting inhibition of VEGF-C and D, the angiopoetin-2 (Ang-2)/Tie-2 pathway, tyrosine kinases, and integrins are reviewed.

EXPERT OPINION

The evolving therapeutic landscape of nAMD is rapidly expanding our toolkit for effective and durable treatment. Recent FDA approvals of faricimab (Vabysmo) and high-dose aflibercept (Eylea HD) for nAMD with potential extension of injection intervals up to four months have been promising developments for patients and providers alike. Further research and innovation, including novel delivery techniques and pharmacologic targets, is necessary to validate the efficacy of developing therapeutics and characterize real-world outcomes, demonstrating promise in expanding treatment durability.

Suprachoroidal Drug Delivery for Macular Edema Associated With Noninfectious Uveitis

Purpose: To evaluate clinical trials in the literature that focus on suprachoroidal drug delivery for the treatment of noninfectious uveitis and other posterior segment diseases. Methods: A synthesis of the literature was performed. Results: In 2021, suprachoroidal space triamcinolone acetonide, a corticosteroid delivery system used for the treatment of uveitic macular edema (ME), was approved by the US Food and Drug Administration. The drug-delivery system targets the suprachoroidal space using a microneedle-based device and has a favorable pharmacokinetic profile. Suprachoroidally administered investigational therapies have also been assessed in clinical trials for other posterior segment diseases, including diabetic ME, retinal vein occlusion, age-related macular degeneration, and choroidal melanoma. Conclusions: The safety and efficacy of suprachoroidal corticosteroid injections to treat uveitic ME have been shown in recent phase III clinical trials. Multiple programs are also investigating this modality of drug delivery for use in many other retinal and choroidal pathologies.

SUPRACHOROIDAL SPACE INJECTION TECHNIQUE: Expert Panel Guidance

PURPOSE

To develop professional guidelines for best practices for suprachoroidal space (SCS) injection, an innovative technique for retinal therapeutic delivery, based on current published evidence and clinical experience.

METHODS

A panel of expert ophthalmologists reviewed current published evidence and clinical experience during a live working group meeting to define points of consensus and key clinical considerations to inform the development of guidelines for in-office SCS injection.

RESULTS

Core consensus guidelines for in-office SCS injection were reached and reported by the expert panel. Current clinical evidence and physician experience supported SCS injection as a safe and effective method for delivering retinal and choroidal therapeutics. The panel established consensus on the rationale for SCS injection, including potential benefits relative to other intraocular delivery methods and current best practices in patient preparation, pre- and peri-injection management, SCS-specific injection techniques, and postinjection management and follow-up.

CONCLUSION

These expert panel guidelines may support and promote standardization of SCS injection technique, with the goal of optimizing patient safety and outcomes. Some aspects of the procedure may reasonably be modified based on the clinical setting and physician judgment, as well as additional study.

Drug-like properties of tyrosine kinase inhibitors in ophthalmology: Formulation and topical availability

Tyrosine kinase inhibitors (TKIs) can inhibit edema and neovascularization, such as in age-related macular degeneration and diabetic retinopathy. However, their topical administration in ophthalmology is limited by their toxicity and poor aqueous solubility. There are multiple types of TKIs, and each TKI has an affinity to more than one type of receptor. Studies have shown that ocular toxicity can be addressed by selecting TKIs that have a high affinity for specific vascular endothelial growth factor receptors (VEGFRs) but a low affinity for epidermal growth factor receptors (EGFRs). Drugs permeate from the aqueous tear fluid into the eye via passive diffusion. Thus, a sustained high concentration of the dissolved drug in the aqueous tear fluid is essential for a successful delivery to posterior tissues such as the retina. Unfortunately, the aqueous solubility of the TKIs that have the most favorable VEGFR/EGFR affinity ratio, that is, axitinib and cabozantinib, is well below 1 µg/mL, making their topical delivery very challenging. This is a review of the drug-like properties of TKIs that are currently being evaluated or have been evaluated as ophthalmic drugs. These properties include their solubilization, cyclodextrin complexation, and ability to permeate from the aqueous tear fluid to the posterior eye segment.

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.

Ocular barriers as a double-edged sword: preventing and facilitating drug delivery to the retina

In recent decades, the growing of the aging population in the world brings increasingly heavy burden of vision-threatening retinal diseases. One of the biggest challenges in the treatment of retinal diseases is the effective drug delivery to the diseased area. Due to the existence of multiple anatomical and physiological barriers of the eye, commonly used oral drugs or topical eye drops cannot effectively reach the retinal lesions. Innovations in new drug formulations and delivery routes have been continuously applied to improve current drug delivery to the back of the eye. Unique ocular anatomical structures or physiological activities on these ocular barriers, in turn, can facilitate drug delivery to the retina if compatible formulations or delivery routes are properly designed or selected. This paper focuses on key barrier structures of the eye and summarizes advances of corresponding drug delivery means to the retina, including various local drug delivery routes by invasive approaches, as well as systemic eye drug delivery by non-invasive approaches.

Suprachoroidal delivery enables targeting, localization and durability of small molecule suspensions

Drug delivery to the suprachoroidal space (SCS®) has become a clinical reality after the 2021 FDA approval of CLS-TA, a triamcinolone acetonide injectable suspension for suprachoroidal use (XIPERE®), administered via a microneedle-based device, the SCS Microinjector®. Suprachoroidal (SC) delivery facilitates targeting, compartmentalization, and durability of small molecule suspensions, thereby potentially addressing some of the efficacy, safety, and treatment burden limitations of current retinal therapies. Herein, the design features of the SCS Microinjector are reviewed, along with the biomechanics of SC drug delivery. Also presented are preclinical evaluations of SC small molecule suspensions from 4 different therapeutic classes (plasma kallikrein inhibitor, receptor tyrosine kinase inhibitor, corticosteroid, complement factor D inhibitor), highlighting their potential for durability, targeted compartmentalization, and acceptable safety profiles following microinjector-based SC delivery. The clinical evaluations of the safety, tolerability and efficacy of SC delivered triamcinolone further supports potential of SC small molecule suspensions as a clinically viable strategy for the treatment of chorioretinal diseases. Also highlighted are current limitations, key pharmacological considerations, and future opportunities to optimize the SC microinjector platform for safe, effective, and potentially long-acting drug delivery for the treatment of chorioretinal disorders.

Disease progression pathways of wet AMD: opportunities for new target discovery

INTRODUCTION

Age-related macular degeneration (AMD) is the leading cause of irreversible blindness among people age 60 years or older in developed countries. Current standard-of-care anti-vascular endothelial growth factor (VEGF) therapy, which inhibits angiogenesis and vascular permeability, has been shown to stabilize choroidal neovascularization and increase visual acuity in neovascular AMD. However, therapeutic limitations of anti-VEGF therapy include limited durability with consequent need for frequent intravitreal injections, and a ceiling of efficacy. Current strategies under investigation include targeting VEGF-C and VEGF-D, integrins, tyrosine kinase receptors, and the Tie2/angiopoietin-2 pathway. A literature search was conducted through November 30, 2021 on PubMed, Medline, Google Scholar, and associated digital platforms with the following keywords: wet macular degeneration, age-related macular degeneration, therapy, VEGF-A, VEGF-C, VEGF-D, integrins, Tie2/Ang2, and tyrosine kinase inhibitors.

AREAS COVERED

The authors provide a comprehensive review of AMD disease pathways and mechanisms involved in wet AMD as well as novel targets for future therapies.

EXPERT OPINION

With novel targets and advancements in drug delivery, there is potential to address treatment burden and to improve outcomes for patients afflicted with neovascular AMD.