title: Local and systemic toxicity of intravitreal melphalan for vitreous seeding in retinoblastoma: a preclinical and clinical study.
abstract: OBJECTIVE
  Intravitreal melphalan is emerging as an effective treatment for refractory vitreous seeds in retinoblastoma, but there is limited understanding regarding its toxicity. This study evaluates the retinal and systemic toxicity of intravitreal melphalan in retinoblastoma patients, with preclinical validation in a rabbit model.
  
  
  METHODS
  Clinical and preclinical, prospective, cohort study.
  
  
  METHODS
  In the clinical study, 16 patient eyes received 107 intravitreal injections of 30 μg melphalan given weekly, a median of 6.5 times (range, 5-8). In the animal study, 12 New Zealand/Dutch Belt pigmented rabbits were given 3 weekly injections of 15 μg of intravitreal melphalan or vehicle to the right eye.
  
  
  METHODS
  Electroretinogram (ERG) responses were recorded in both humans and rabbits. For the clinical study, ERG responses were recorded at baseline, immediately before each injection, and at each follow-up visit; 82 of these studies were deemed evaluable. Median follow-up time was 5.2 months (range, 1-11). Complete blood counts (CBCs) were obtained on the day of injection at 46 patient visits. In the animal study, ERG responses were obtained along with fluorescein angiography, CBCs, and melphalan plasma concentration. After humane killing, the histopathology of the eyes was evaluated.
  
  
  METHODS
  For the clinical study, we measured peak-to-peak ERG amplitudes in response to 30-Hz photopic flicker stimulation with comparisons between ERG studies before and after intravitreal melphalan. For the animal study, we collected ERG parameters before and after intravitreal melphalan injections with histopathologic findings.
  
  
  RESULTS
  By linear regression analysis, over the course of weekly intravitreal injections in retinoblastoma patients, for every additional injection, the ERG amplitude decreased by approximately 5.8 μV. The ERG remained stable once the treatment course was completed. In retinoblastoma patients, there were no grade 3 or 4 hematologic events. One week after the second injection in rabbits, the a- and b-wave amplitude declined significantly in the melphalan treated eyes compared with vehicle-treated eyes (P<0.05). Histopathology revealed severely atrophic retina.
  
  
  CONCLUSIONS
  Weekly injections of 30 μg of melphalan can result in a decreased ERG response, which is indicative of retinal toxicity. These findings are confirmed at an equivalent dose in rabbit eyes by ERG measurements and by histopathologic evidence of severe retinal damage. Systemic toxicity with intravitreal melphalan at these doses in humans or rabbits was not detected.
authors.affiliation: Ophthalmic Oncology Service, Memorial Sloan-Kettering Cancer Center, New York, New York. Electronic address: francij1@mskcc.org.
authors.forename: Jasmine H
authors.initials: JH
authors.lastname: Francis
authors.affiliation: Unidad de Farmacocinética Clínica, Hospital de Pediatría JP Garrahan, Buenos Aires, Argentina; CONICET: National Scientific and Technical Research Council, Buenos Aries, Argentina.
authors.forename: Paula
authors.initials: P
authors.lastname: Schaiquevich
authors.affiliation: Unidad de Farmacocinética Clínica, Hospital de Pediatría JP Garrahan, Buenos Aires, Argentina.
authors.forename: Emiliano
authors.initials: E
authors.lastname: Buitrago
authors.affiliation: Laboratorio de Farmacologia, CIVETAN-CONICET, Facultad de Veterinaria, Universidad Nacional del Centro de Buenos Aires, Tandil, Argentina.
authors.forename: María José
authors.initials: MJ
authors.lastname: Del Sole
authors.affiliation: Laboratorio de Investigaciones Oculares, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina.
authors.forename: Gustavo
authors.initials: G
authors.lastname: Zapata
authors.affiliation: Fundación Oftalmológica Argentina Jorge Malbrán, Buenos Aires, Argentina.
authors.forename: J Oscar
authors.initials: JO
authors.lastname: Croxatto
authors.affiliation: Ophthalmic Oncology Service, Memorial Sloan-Kettering Cancer Center, New York, New York.
authors.forename: Brian P
authors.initials: BP
authors.lastname: Marr
authors.affiliation: Ophthalmology, Mount Sinai School of Medicine, New York, New York.
authors.forename: Scott E
authors.initials: SE
authors.lastname: Brodie
authors.affiliation: Laboratorio de Investigaciones Oculares, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Berra
authors.affiliation: Servicio de Hematología-Oncología, Hospital de Pediatría JP Garrahan, Buenos Aires, Argentina.
authors.forename: Guillermo L
authors.initials: GL
authors.lastname: Chantada
authors.affiliation: Ophthalmic Oncology Service, Memorial Sloan-Kettering Cancer Center, New York, New York.
authors.forename: David H
authors.initials: DH
authors.lastname: Abramson
mesh_terms: D000818:Animals; D018906:Antineoplastic Agents, Alkylating / Q000008:administration & dosage / Q000009:adverse effects / Q000633:toxicity*; D001772:Blood Cell Count; D002648:Child; D002675:Child, Preschool; D004353:Drug Evaluation, Preclinical; D004596:Electroretinography; D005260:Female; D005451:Fluorescein Angiography; D006801:Humans; D007223:Infant; D058449:Intravitreal Injections; D008297:Male; D008558:Melphalan / Q000008:administration & dosage / Q000009:adverse effects / Q000633:toxicity*; D009366:Neoplasm Seeding; D011446:Prospective Studies; D011817:Rabbits; D012044:Regression Analysis; D019572:Retinal Neoplasms / Q000188:drug therapy* / Q000503:physiopathology; D012175:Retinoblastoma / Q000188:drug therapy* / Q000503:physiopathology; D014822:Vitreous Body / Q000473:pathology
chemical_list: D018906:Antineoplastic Agents, Alkylating; D008558:Melphalan