Recombinant IL-7 enhances the potency of GM-CSF-secreting tumor cell immunotherapy

IL-7 is known for its role in lymphopoiesis and T-cell homeostasis. In addition, its capacity to augment the immune response to weak or low affinity antigens makes it an ideal candidate to evaluate in combination with a GM-CSF-secreting tumor cell immunotherapy, which has been shown to elicit broad humoral and cellular immune responses. The studies reported here show that IL-7, when combined with a GM-CSF-secreting tumor cell immunotherapy, significantly prolonged the survival of tumor-bearing mice. The enhanced anti-tumor protection correlated with an increased number of activated dendritic cells (DC) and T cells in lymphoid tissues, such as the draining lymph nodes (DLN) and spleen. Moreover, an increased number of activated effector T cells were found in the tumor microenvironment, correlating with a more potent systemic tumor-specific T-cell response than each monotherapy alone. Taken together, these studies demonstrate that IL-7 augments the anti-tumor response of a GM-CSF-secreting tumor cell immunotherapy in preclinical models.