title: Intravitreal methotrexate resistance in a patient with primary intraocular lymphoma.
abstract: OBJECTIVE
  To describe the clinical course of a patient with multiple recurrences of primary intraocular lymphoma (PIOL).
  
  
  METHODS
  Interventional case report,
  
  
  METHODS
  Retrospective chart review.
  
  
  RESULTS
  A 57-year-old female treated with multiple intravitreal methotrexate injections became refractory to intravitreal methotrexate after a year. Lymphoma cells evaluated using immunocytochemistry and confocal microscopy showed aberrant multidrug resistance-related protein (MRP) and decreased reduced folate carrier (RFC) and folate binding protein (FBP) expression compared to PIOL cells from another patient clinically responsive to methotrexate.
  
  
  CONCLUSIONS
  This case suggests that alterations in the transport of methotrexate across the cell membrane might contribute to resistance following repeated intravitreal injections.
authors: Laboratory of Immunology, National Eye Institute, National Institutes of Health, Bethesda, Maryland, USA. nidasen@gwu.edu
authors: H Nida
authors: HN
authors: Sen
authors: Chi-Chao
authors: CC
authors: Chan
authors: Gordon
authors: G
authors: Byrnes
authors: Robert N
authors: RN
authors: Fariss
authors: Robert B
authors: RB
authors: Nussenblatt
authors: Ronald R
authors: RR
authors: Buggage
mesh_terms: D002352:Carrier Proteins / Q000378:metabolism; D004334:Drug Administration Schedule; D004351:Drug Resistance; D005134:Eye Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D005260:Female; D058973:Folate Receptors, GPI-Anchored; D005654:Fundus Oculi; D006801:Humans; D007267:Injections; D008228:Lymphoma, Non-Hodgkin / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D008297:Male; D026901:Membrane Transport Proteins / Q000378:metabolism; D008727:Methotrexate / Q000008:administration & dosage* / Q000627:therapeutic use; D018613:Microscopy, Confocal; D008875:Middle Aged; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000378:metabolism; D009364:Neoplasm Recurrence, Local / Q000473:pathology; D011956:Receptors, Cell Surface / Q000378:metabolism; D058978:Reduced Folate Carrier Protein; D013194:Staining and Labeling; D014822:Vitreous Body
chemical_list: D002352:Carrier Proteins; D058973:Folate Receptors, GPI-Anchored; D026901:Membrane Transport Proteins; D008727:Methotrexate; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D011956:Receptors, Cell Surface; D058978:Reduced Folate Carrier Protein; C548699:SLC19A1 protein, human