Defining the therapeutic window of vertebral photodynamic therapy in a murine pre-clinical model of breast cancer metastasis using the photosensitizer BPD-MA (Verteporfin)

Breast Cancer Res Treat. 2010 Jan;119(2):325-33. doi: 10.1007/s10549-009-0356-7. Epub 2009 Mar 5.


Breast cancer is known to cause metastatic lesions in the bone, which can lead to skeletal-related events. Currently, radiation therapy and surgery are the treatment of choice, but the success rate varies and additional adjuncts are desirable. Photodynamic therapy (PDT) has been applied successfully as a non-radiative treatment for numerous cancers. Earlier work has shown that the athymic rat model is suitable to investigate the effect of PDT on bone metastasis and benzoporphyrin-derivative monoacid ring A (BPD-MA; verteporfin) has been shown to be a selective photosensitizer. The aim of this study was to define the therapeutic window of photosensitizer with regard to drug and light dose. Human breast carcinoma cells (MT-1)-stable transfected with the luciferase gene-were injected intra-cardiacally into athymic rats. At 14 days, the largest vertebral lesion by bioluminescence imaging was targeted for single treatment PDT. A drug escalating-de-escalating scheme was used (starting drug dose and light energy of 0.2 mg/kg and 50 J, respectively). Outcomes included 48 h post-treatment bioluminescence of remaining viable tumour, histomorphometric assessment of tumour burden, and neurologic evaluation. The region of effect by bioluminescence and histology increased with increasing drug dose and light energy. A safe and effective drug-light dose combination in this model appears to be 0.5 mg/kg BPD-MA and applied light energy of less than 50 J for the thoracic spine and 1.0 mg/kg and 75 J for the lumbar spine. For translation to clinical use, it is an advantage that BPD-MA (verteporfin), a second-generation photosensitizer, is already approved to treat age-related macular degeneration. Overall, PDT represents an exciting potential new minimally-invasive local, safe and effective therapy in the management of patients with spinal metastases.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Breast Neoplasms / genetics
  • Breast Neoplasms / pathology*
  • Cell Line, Tumor
  • Dose-Response Relationship, Drug
  • Dose-Response Relationship, Radiation
  • Female
  • Genes, Reporter
  • Humans
  • Luciferases / genetics
  • Lumbar Vertebrae / drug effects*
  • Lumbar Vertebrae / pathology
  • Mice
  • Photochemotherapy / methods*
  • Photosensitizing Agents / pharmacology*
  • Porphyrins / pharmacology*
  • Rats
  • Rats, Nude
  • Spinal Neoplasms / drug therapy*
  • Spinal Neoplasms / genetics
  • Spinal Neoplasms / secondary
  • Thoracic Vertebrae / drug effects*
  • Thoracic Vertebrae / pathology
  • Time Factors
  • Transfection
  • Verteporfin
  • Xenograft Model Antitumor Assays


  • Photosensitizing Agents
  • Porphyrins
  • Verteporfin
  • Luciferases