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Richard Dreyer, Gregg Kokame, Glenn Stoller, Howard Shapiro, Dafeng Chen, Lisa Tuomi; Early vs Delayed 15-Letter Responders to Ranibizumab Treatment in Year 1 of the Phase III HARBOR Trial. Invest. Ophthalmol. Vis. Sci. 2013;54(15):3829.
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© ARVO (1962-2015); The Authors (2016-present)
This subanalysis of the phase III HARBOR study examined patterns of visual acuity (VA) response over time to ranibizumab 0.5 mg or 2.0 mg administered on a monthly or as-needed (PRN) basis in patients with subfoveal neovascular age-related macular degeneration (wet AMD). Potential baseline predictors of treatment response in early 15-letter responders vs delayed 15-letter responders were also identified.
Patients (n=1097) were randomized to receive intravitreal ranibizumab 0.5 mg or 2.0 mg monthly or PRN after three monthly loading doses. Best-corrected visual acuity (BCVA), as observed, was measured at baseline (n=1097), and at Months (M) 3 (n=1057), 6 (n=1028), 9 (n=1013), and 12 (n=1000). Patients were categorized based on VA changes from baseline as “early responders” (ie, gained ≥15 letters from baseline at M3; n=266) or “delayed responders” (did not gain ≥15 letters from baseline at M3, but did so at M12; n=138).
At M3, the proportion of patients who gained ≥15 letters from baseline in BCVA was: 24% (0.5 mg monthly), 25% (0.5 mg PRN), 26% (2.0 mg monthly), and 26% (2.0 mg PRN). Some patients who did not achieve a ≥15 letter gain at M3 continued to experience VA increases throughout treatment, as the proportion of patients who gained ≥15 letters from baseline in BCVA at M12 was 36%, 32%, 37%, and 35%, respectively. At M12 (n=256), early responders maintained their ≥15 letter gain in 83%, 76%, 86% and 82% of patients, respectively. Compared with the M3 visit, an additional 11-12% of patients treated with ranibizumab monthly and 7-9% of patients treated with ranibizumab PRN gained 15 letters of vision at M12. Compared with delayed responders, those that were early responders tended to have worse mean VA at baseline, with significant differences observed in the 0.5 mg monthly (P=0.0013) and 2.0 mg monthly (P=0.022) treatment groups.
A subset of patients who do not experience significant gains (ie, ≥15 letters) in BCVA at M3 can, with continued ranibizumab treatment, achieve significant gains at M12. A ≥15 letter gain in vision at M3 may indicate sustained efficacy with a less-than-monthly dosing regimen, as 76-82% of PRN patients maintained these gains at M12.
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