Dendritic cell immunotherapy induces antitumour response in parathyroid carcinoma and neuroendocrine pancreas carcinoma.

Parathyroid carcinomas and neuroendocrine carcinomas of the pancreas are rare malignancies in humans. Because of their low radio- and chemosensibility, they fail to respond to conventional therapy. We therefore tested a dendritic cell immunotherapy in an attempt to control the tumour growth in two patients. Studies on mice and humans have demonstrated the potent capacity of dendritic cells to induce specific antitumour immunity. Mature dendritic cells were generated from peripheral blood monocytes in the presence of granulocyte/macrophage colony-stimulating factor, interleukin 4 and tumour necrosis factor alpha. Dendritic cells were either loaded with parathyroid hormone (PTH) or with (pancreas) tumour-derived lysate (TL), respectively, and were delivered by subcutaneous injections. All immunizations were well tolerated with no side effects, and were administered on an outpatient basis. After repeated vaccinations, specific in vivo immune response was demonstrated by positive delayed-type hypersensitivity (DTH) toward PTH or TL, demonstrating the efficient generation of antigen-specific memory T-cells. DTH reactivity was accompanied by a significant decrease of tumour markers in both patients. This approach might be generally applicable to other advanced, radio- and chemotherapy-resistant endocrine malignancies.