Purpose
Intravitreal antiVEGF is the treatment of choice for exudative age-related macular degeneration (eAMD), but the therapy is transient and requires retreatment. Since a synergism between antiVEGF therapy and radiation has been observed in oncology and possibly in eAMD, this phase I/II prospective, randomized, double-blinded sham-controlled study was initiated to explore the safety and efficacy of proton beam irradiation (PBI) combined with antiVEGF therapy in eAMD.
Methods
Thirty eyes (30 subjects) with newly-diagnosed eAMD were randomized 1:1:1 to 24Gy: 16Gy: sham PBI, delivered in two fractions, 24 hours apart. Subjects were seen monthly and treated with intravitreal ranibizumab (0.5mg) or bevicizumab (1.25mg) monthly for the first 3 months and prn thereafter for new macular fluid on optical coherence tomography (OCT) or macular hemorrhage on examination. Main outcome measures were incidence of radiation retinopathy and severe vision loss (> 15 letter loss), mean number of antiVEGF therapies, and change in BCVA. Changes in macular morphology on OCT and the neovascular lesion on angiography were also assessed.
Results
The groups were evenly distributed in terms of demographics, BCVA, and lesion size at baseline. Interim analysis of the first 19 subjects who completed the one-year follow-up included the following: 24Gy (n=7); 16Gy (n=6); sham (n=6). An improvement in mean BCVA was noted in all three groups compared to baseline (p=0.02) with no significant differences between groups. The mean number of additional antiVEGF treatments after month 3 was 2 ±1.1 (24Gy Group) vs 5 ±1.6 (sham Group) (p=0.005). There was a trend toward complete dryness on OCT at month 3 in the 24Gy Group compared to the sham Group (p=0.16). Imaging analysis indicated a trend towards reduction in central macular thickness and size of pigment epithelial detachments with combination treatments (both 16Gy and 24Gy). There was no case of severe visual loss or radiation retinopathy.
Conclusions
Interim one-year analysis revealed no safety concerns with combination therapy and a possible synergistic effect utilizing 24Gy PBI, resulting in a decreased treatment burden. The complete one-year follow-up data will be presented to determine whether these initial findings may also be applicable the 16Gy group.