First Comprehensive Post-Marketing Safety Comparison Reveals Differing Adverse Event Profiles for Geographic Atrophy Treatments

• New research using FDA Adverse Event Reporting System data identified 752 adverse events with pegcetacoplan compared to 80 with avacincaptad pegol in geographic atrophy treatment.
• Pegcetacoplan showed a broader range of adverse events including iris hemorrhage and bacterial endophthalmitis, while avacincaptad pegol demonstrated a narrower risk profile with events like choroidal neovascularization.
• Researchers caution that the disparity in reported events may reflect differences in market availability timing, prescribing patterns, or intrinsic risk profiles of these complement inhibitors.

Researchers have conducted the first comprehensive post-marketing safety comparison between pegcetacoplan and avacincaptad pegol, two recently approved treatments for geographic atrophy (GA), revealing significant differences in their adverse event profiles. The study, published in the American Journal of Ophthalmology, analyzed data from the FDA Adverse Event Reporting System (FAERS) to characterize real-world safety outcomes beyond clinical trial reports.

The investigation identified 752 patients with adverse events (AEs) associated with pegcetacoplan compared to just 80 patients with AEs linked to avacincaptad pegol. This substantial numerical difference has prompted researchers to examine potential explanations for this disparity.

Distinct Adverse Event Profiles

Pegcetacoplan was associated with a broader spectrum of ocular adverse events, including anterior segment (iris) hemorrhage, iris neovascularization, choroidal neovascularization, intraocular injection complications, hemorrhagic occlusive retinal vasculitis, retinal occlusive vasculitis, and bacterial endophthalmitis.

In contrast, avacincaptad pegol demonstrated a narrower adverse event profile, with reported events including choroidal neovascularization, vitritis, dry age-related macular degeneration (AMD), and cystoid macular edema.

Clinical Trial Safety Data Context

The researchers contextualized these findings against the backdrop of clinical trial safety data. The Phase III OAKS and DERBY trials for pegcetacoplan (n=1,258) showed that 61.6% of patients receiving monthly injections experienced treatment-emergent AEs in the study eye by 24 months, compared to 55% in the bimonthly group and 46.3% in the placebo group. Common adverse events included vitreous floaters, new-onset exudative AMD, retinal hemorrhage, and decreased visual acuity, with three serious cases of ischemic optic neuropathy reported.

For avacincaptad pegol, the GATHER1 Phase II/III trial (n=286) reported treatment-emergent AEs in 58.2% of patients receiving the FDA-approved 2mg dosage, rising to 73.5% in the 4mg group, compared to 40.9% in the sham group. At 18 months, adverse events occurring at rates ≥2% included conjunctival hyperemia, conjunctival edema, punctate keratitis, cataracts, vitreous detachment, choroidal neovascularization, eye pain, and reduced visual acuity.

The GATHER2 Phase III trial for avacincaptad pegol additionally reported dry eye, increased ocular pressure, and macular neovascularization as adverse events occurring in ≥2% of patients (n=225) at month 12.

Interpreting the Disparity in Adverse Event Reports

The study authors proposed several explanations for the significant difference in the number of reported adverse events between the two treatments:

1. Intrinsic risk differences: Pegcetacoplan may inherently carry a greater risk profile due to its mechanism of action.
2. Reaction noticeability: Adverse reactions to pegcetacoplan might be more noticeable or severe, leading to higher reporting rates.
3. Prescription frequency: Pegcetacoplan may be prescribed more frequently than avacincaptad pegol in clinical practice.
4. Market availability timing: Avacincaptad pegol received FDA approval six months after pegcetacoplan, potentially explaining some of the reporting disparity.
5. Clinical expertise development: Clinicians' growing familiarity with pegcetacoplan may have improved their ability to detect and report adverse events.

Clinical Implications and Future Directions

The researchers emphasized that while clinical trial data suggested comparable adverse event rates between both complement inhibitors, this real-world analysis revealed potentially important differences in their safety profiles. However, they cautioned that avacincaptad pegol data carried a higher uncertainty level due to the smaller sample size.

"Our findings are subject to the real-world utilization of these agents, but they emphasize the necessity of a proactive, risk-based approach to patient management," the authors noted in their paper.

The study underscores the importance of ongoing pharmacovigilance for both treatments. The authors concluded that continued surveillance of adverse events is essential "to better elucidate the long-term implications of their mechanisms of action and inform their safe use in clinical practice."

This research represents an important step in understanding the real-world safety profiles of these novel geographic atrophy treatments, providing clinicians with valuable information to guide treatment decisions and patient monitoring strategies.