Development of Geographic Atrophy is Similar Across Ranibizumab Dosing Regimens

November 16, 2020
Jonathan Alicea

A post-hoc analysis of the CANTREAT trial finds similar GA frequency, characteristics, and surface area between patients in treat-and-extend and once-monthly regimen cohorts.

The role of anti-VEGF treatment in the development of geographic atrophy (GA) in patients with neovascular age-related macular degeneration (nAMD) is still unclear. However, previous analyses have established a positive correlation between the number of anti-VEGF injection and GA developments — and yet, ascertainment of the direct impact of treatment on GA remains difficult.

A new post-hoc analysis of the CANTREAT study, the largest Canadian randomized, open-label, non-inferiority, multicenter trial of ranibizumab, found that new or progressive atrophy had similar frequency, characteristics, and surface area between patients in treat-and-extend and once-monthly regimen cohorts. These similarities were noted at 12, 24, and 36 months.

The findings were presented this weekend at the American Academy of Ophthalmology (AAO) 2020 Virtual Conference.

A team, led by Parnian Arjmand, MD, MSc, Fellow at Sunnybrook Health Sciences Center, Toronto, examined a small subset of patients enrolled in the CANTREAT trial in order to evaluate and characterize GA over the course of the study and extension periods.

They defined GA as well-defined areas of atrophy within μm of the macula. They excluded atrophy associated within retinal pigment epithelium tears.

Arjmand and colleagues retrospectively graded fundus autofluorescence FAF photos at baseline, 12, 24, and 36 months for center-involving GA.

Overall, they assessed a total of 60 patients, evenly split between the once-monthly and treat-and-extend regimen arms. All patients had nAMD, received intravitreal ranibizumab, and completed at least 24 months of the study. An additional 8 patients completed 36 in the extension.

At baseline, GA was identified in 66% of all patients, with 65.7% of those being multifocal.

At 12 months, new GA was identified in 16.6% and 20% of the once-monthly and treat-and-extend cohorts, respectively (P>.05). Additionally, they found that eyes with no GA by 12 months did not develop new GA by 24 or 36 months of follow-up.

Using a two-tailed unequal variance t test, the investigators determined the mean change in square-root area of GA from baseline in the once-monthly arm was 243.70 μm versus 340.56 μm in the treat-and-extend arm at 12 months (P = .59).

At 24 months, the mean change in square root area was 342.62 μm for the once-monthly arm and 415.04 μm for the treat-and-extend arm (P = .69).

And finally, at 36 months, the mean change was 1003.27 μm and 1374.61 μm for once-monthly and treat-and-extend arms, respectively.

“I think the early results perhaps suggest that geographic atrophy is not necessarily induced by the number of injections that a patient gets — at least from this study itself,” Arjmand told HCPLive® in a recent interview.

She went on to acknowledge that the small cohort assessed precludes one from drawing any large conclusions. Furthermore, she noted that it is still particularly difficult to determine if injections do in fact exacerbate GA, or if exacerbation is due to a more aggressive nature of the disease.