title: Pattern of antigen expression in metastases after radioimmunotherapy of a syngeneic rat colon carcinoma utilizing the BR96 antibody.
abstract: BACKGROUND
  Repeated administration of antibody-based therapies such as radioimmunotherapy depends on preserved antigen expression in tumor lesions. The purpose of this study was to evaluate whether the antigen expression in metastases observed after radioimmunotherapy differs from that of untreated primary tumors.
  
  
  RESULTS
  30 of the 35 Brown Norway rats with syngeneic colon carcinoma treated with 400 MBq/kg 177Lu-DOTA-BR96 exhibited consistent complete response of the primary tumor. 13 animals developed metastases that were detected after treatment. The antigen expression was reduced in 17 of 23 metastases detected after radioimmunotherapy compared with untreated tumors. No tumors completely lacked positively stained tumor cells.
  
  
  CONCLUSIONS
  Although it was not possible to demonstrate that the antigen reduction is triggered by the radioimmunotherapy this result stress the importance of considering the risk of reduced antigen expression in metastases after radioimmunotherapy prior to further targeted therapies.
authors.affiliation: Department of Oncology, Lund University, Lund, Sweden.
authors.forename: Erika
authors.initials: E
authors.lastname: Elgström
authors.affiliation: Department of Oncology, Lund University, Lund, Sweden.
authors.forename: Sophie E
authors.initials: SE
authors.lastname: Eriksson
authors.affiliation: Department of Medical Radiation Physics, Lund University, Lund, Sweden.
authors.forename: Tomas G
authors.initials: TG
authors.lastname: Ohlsson
authors.affiliation: Department of Oncology, Lund University, Lund, Sweden.|Department of Oncology, Skåne University Hospital, Lund, Sweden.
authors.forename: Jan
authors.initials: J
authors.lastname: Tennvall
authors.affiliation: Department of Oncology, Lund University, Lund, Sweden.
authors.forename: Rune
authors.initials: R
authors.lastname: Nilsson