Immunostimulation versus immunosuppression after multiple vaccinations: the woes of therapeutic vaccine development.

Three articles in this issue of Clinical Cancer Research show how multiple vaccinations can lead to immunosuppression. Moreover, two studies in patients show that granulocyte macrophage colony-stimulating factor (GM-CSF) as an adjuvant immunostimulant to different kind of vaccines can lead to adverse outcome in terms of relapse-free and overall survival. Modulation of regulatory T-cell activity may be required to overcome this outcome and may be crucial for the successful development of therapeutic vaccines.