Immunomodulation characteristics by thermal ablation therapy in cancer patients

Thermal ablation therapy has recently emerged as a promising noninvasive treatment modality for localized solid malignancies. Except its direct tumor-cell-killing effect on local tumor tissues, the immunomodulatory effect has also long been noticed which too has substantial effect on clinical outcome, but it is complicated. Though much has been investigated and rich evidences have been achieved, the fundamental state and profile of immunomodulation by thermal ablation in cancer patients, its exact mechanism, especially the systematic mechanism, and its effect on antitumor immunity remain unclear.

In this study, we dynamically monitored the immunomodulation by thermal ablation through combined analysis of peripheral lymphocyte populations, functional T cell subtype Th1 (CD3+CD4+IFN-r+), Th2 (CD3+CD4+IL-4+), Tc1 (CD3+CD8+IFN-r+), Tc2 (CD3+CD8+IL-4+) and mRNA expression of several immune-active and -suppressive molecules including CD25, CD28, cytotoxic T-lymphocyte-associated protein 4, programmed cell death protein 1, Foxp3, transforming growth factor beta (TGF-β) and interleukin (IL-10) in 16 cancer patients.

The results show that local cancer thermal ablation modulated the cellular immunity characterized by obviously downregulation of regulatory T cells (Treg) and cytotoxicity T cells followed by CD4, CD8 and suppressor T cells (Ts), but upregulation of natural killer (NK) cells and mRNA expression of TGF-β and IL-10, suggesting a slight inhibition of the cellular immunity which may affect antitumor immunity.

We suggest a further immunomodulation therapy after thermal therapy for recovering a Th1- and Tc1-dominant immune response for pursuing a better long-term antitumor immunity.