Intravitreal Adalimumab in Inherited and Degenerative Retinal Diseases

Retinitis pigmentosa (RP) represents a genetically and phenotypically heterogeneous group of inherited retinal dystrophies characterized by progressive photoreceptor degeneration, classically beginning with rod dysfunction and followed by cone loss. Patients typically present with nyctalopia, peripheral visual-field constriction, and, in advanced stages, central vision impairment. Despite significant advances in gene-specific, cell-based, and prosthetic approaches, most patients currently lack broadly applicable interventions capable of slowing or reversing disease progression across RP's wide genotypic spectrum.

Recent evidence reframes RP as not only a genetic degenerative process but also a state of chronic para-inflammation in the outer retina. Microglial activation, breakdown of the blood-retinal barrier, and overexpression of pro-inflammatory cytokines-particularly tumor necrosis factor-alpha (TNF-α)-have been implicated in accelerating photoreceptor apoptosis and secondary cone degeneration. Within this biological context, adalimumab (ADA), a fully human monoclonal antibody that selectively inhibits TNF-α, offers a mechanism-based therapeutic rationale for mitigating inflammatory injury in RP.

This prospective, single-arm pilot study was designed to evaluate the functional impact and ocular safety of intravitreal adalimumab in patients with RP. Participants received three intravitreal ADA injections (2 mg/0.05 mL) at two-month intervals (M0, M2, M4). The primary assessments included best-corrected visual acuity (BCVA, LogMAR), visual-field metrics (FPDI, MD, PSD; using 10-2 for advanced and 24-2 for less advanced disease), and 30-Hz flicker ERG when measurable. Structural endpoints comprised OCT-derived central macular thickness and ellipsoid zone (EZ) length. Outcomes were analyzed for pre-post change over six months (M0-M6) and feasibility in a real-world clinical research setting.

This exploratory study aims to generate foundational data to guide future controlled trials of anti-TNF therapy in inherited retinal degenerations with inflammatory components.

Inclusion criteria

Age ≥ 18 years.

• Clinical diagnosis of retinitis pigmentosa (RP) or EMAP (Extensive Macular Atrophy with Pseudodrusen-like Appearance) confirmed by multimodal evaluation.
• Best-corrected visual acuity (BCVA) ≥ counting fingers at 1 meter (approximately ≤ 1.9 logMAR) in the study eye.
• Measurable visual field on iCare COMPASS (10-2 or 24-2) with acceptable reliability indices.
• Clear ocular media adequate for safe intravitreal injection and high-quality OCT imaging.
• Ability and willingness to provide written informed consent.
• Ability to comply with scheduled study visits (Baseline [M0], Day 7-14 after injections, Month 2 [M2], Day 7-14, Month 4 [M4], Day 7-14, and Month 6 [M6]).
• For ERG subset only: presence of a recordable baseline 30-Hz flicker ERG response (signal-to-noise ratio ≥ 3:1 and amplitude ≥ 3.0 µV).
• Note: Absence of a measurable flicker ERG response does not exclude participation in the main study.

Exclusion criteria

• Active ocular inflammation (anterior, intermediate, or posterior uveitis) or infectious ocular disease in the study eye.
• Active choroidal neovascularization or other macular diseases unrelated to RP or EMAP.
• Uncontrolled glaucoma (intraocular pressure > 21 mmHg despite therapy) or optic neuropathies not related to RP or EMAP.
• Significant media opacity that may impair imaging quality or safe intravitreal injection.
• Recent ocular interventions that may confound study outcomes, including:
• Intravitreal therapy within 3 months prior to enrollment.
• Periocular corticosteroid injection within 3 months prior to enrollment.
• Major intraocular surgery within 3 months prior to enrollment.
• Known hypersensitivity to adalimumab, povidone-iodine, local anesthetics, or any formulation components.
• Coagulopathy or contraindications to ocular injections (platelet count < 100,000/µL or INR > 1.5 unless corrected).
• Pregnancy or breastfeeding.
• Women of childbearing potential unwilling to use effective contraception during the study period.
• Uncontrolled systemic disease that increases risk or interferes with study participation or completion.
• Participation in another interventional clinical trial within 3 months prior to enrollment.