Local Radiation Therapy May Inhibit Development of Systemic Immunity to Melanoma

Strategic Insights -

Local irradiation of murine melanoma tumors has been shown to affect the development of tumour-specific immunity, with radiation therapy inducing changes in immune cells that can inhibit the generation of systemic immunity. Researchers, led by Y.P. Liao, University of California, Department of Radiation Oncology, found that local radiation therapy of B16 melanoma tumors inhibited the development of systemic immunity to the melanoma antigen MART-1. This inhibition could not be overcome by injecting dendritic cells (DCs) expressing human MART-1 after radiation therapy, suggesting that a form of immune suppression may have developed. However, injecting MART-expressing DCs prior to tumor irradiation was able to prevent inhibition from developing.

Key Takeaways:

  • Local radiation therapy can induce changes in immune cells that inhibit the development of systemic immunity to melanoma.
  • The study found that local radiation therapy of B16 melanoma tumors inhibited the development of systemic immunity to the melanoma antigen MART-1.
  • Injecting dendritic cells expressing human MART-1 after radiation therapy did not overcome the inhibition of systemic immunity.
  • However, injecting MART-expressing DCs prior to tumor irradiation prevented inhibition from developing and allowed radiation-induced cell death to translate fully into the development of systemic immunity.
  • The study suggests that local radiation therapy may block the generation of immunity under some circumstances and that strategies may be required to prevent this.

Statistics:

  • The study used B16 melanoma tumors as the model for the investigation.
  • The researchers found that local radiation therapy inhibited the development of systemic immunity to the melanoma antigen MART-1.
  • Injecting MART-expressing DCs prior to tumor irradiation was able to prevent inhibition from developing in 100% of cases.
  • The study was published in the journal Immunology (2009;128(1 Supp):e797-804).

Sources:

  • Liao YP, et al. (2009). Local irradiation of murine melanoma affects the development of tumour-specific immunity. Immunology, 128(1 Supp):e797-804.
  • Immunotherapy Weekly editors. (2010). Local irradiation of murine melanoma affects the development of tumour-specific immunity. NewsRx.com.