title: Stereotactic radiotherapy for wet age-related macular degeneration (INTREPID): influence of baseline characteristics on clinical response.
abstract: OBJECTIVE
  To determine which patients respond best to stereotactic radiotherapy (SRT) for neovascular age-related macular degeneration.
  
  
  METHODS
  Participants (n = 230) receiving intravitreal anti-vascular endothelial growth factor injections for neovascular age-related macular degeneration enrolled in a randomized, double-masked sham-controlled trial comparing 16 Gray, 24 Gray, or Sham SRT. In a post hoc analysis, participants were grouped according to their baseline characteristics, to determine if these influenced SRT efficacy.
  
  
  RESULTS
  At 52 weeks, SRT was most effective for lesions ≤4 mm in greatest linear dimension and with a macular volume greater than the median value of 7.4 mm. For 26% of the participants with both these characteristics, SRT resulted in 55% fewer ranibizumab injections (2.08 vs. 4.60; P = 0.0002), a mean visual acuity change that was 5.33 letters superior to sham (+2.18 vs. -3.15 letters; P = 0.0284), and a 71.1-μm greater reduction in mean central subfield thickness (-122.6 vs. -51.5 μm; P = 0.027). Other features associated with a positive response to SRT included pigment epithelial detachment and the absence of fibrosis.
  
  
  CONCLUSIONS
  Stereotactic radiotherapy is most effective for neovascular age-related macular degeneration lesions that are actively leaking at the time of treatment, and no larger than the 4-mm treatment zone.
authors.affiliation: *Department of Ophthalmology, School of Medicine, King's College London, London, United Kingdom; †Oraya Therapeutics, Inc, Newark, California; ‡The International Drug Development Institute, Louvain-la-Neuve, Belgium; and §Byers Eye Institute, Horngren Family Vitreoretinal Center, Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, California.
authors.forename: Timothy L
authors.initials: TL
authors.lastname: Jackson
authors.forename: E Mark
authors.initials: EM
authors.lastname: Shusterman
authors.forename: Mark
authors.initials: M
authors.lastname: Arnoldussen
authors.forename: Erik
authors.initials: E
authors.lastname: Chell
authors.forename: Kun
authors.initials: K
authors.lastname: Wang
authors.forename: Darius M
authors.initials: DM
authors.lastname: Moshfeghi
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D020533:Angiogenesis Inhibitors / Q000627:therapeutic use; D061067:Antibodies, Monoclonal, Humanized / Q000627:therapeutic use; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D058449:Intravitreal Injections; D008297:Male; D008875:Middle Aged; D016634:Radiosurgery / Q000379:methods*; D000069579:Ranibizumab; D017211:Treatment Failure; D042461:Vascular Endothelial Growth Factor A / Q000037:antagonists & inhibitors; D014792:Visual Acuity / Q000502:physiology; D057135:Wet Macular Degeneration / Q000188:drug therapy / Q000473:pathology / Q000601:surgery*
chemical_list: D020533:Angiogenesis Inhibitors; D061067:Antibodies, Monoclonal, Humanized; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; D000069579:Ranibizumab