Induction of cellular immune responses in patients with stage-I multiple myeloma after vaccination with autologous idiotype-pulsed dendritic cells.

Idiotype vaccines have shown both biological efficacy and clinical benefit in lymphoma. Circulating idiotype proteins (Id) in multiple myeloma patients offer a suitable target for immunotherapy. So far, specific immune responses after vaccination with Ids have been evaluated mostly in advanced myeloma. We explored the potential of dendritic-cell (DC)-based immunotherapy in 9 patients with stage-I disease. Mature monocyte-derived Id-pulsed DCs and keyhole limpet hemocyanin (KLH) were administered at dose levels between 2 and 20×10⁶ cells. Patients received 5 immunizations every 4 weeks. A median number of 6.8×10⁶ DCs were administered per vaccination. Five out of 9 patients (56%) developed Id-specific T cells as showed in proliferation assays and 8 out of 9 patients (89%) showed specific T-cell-mediated cytokine release after Id stimulation. The cytokine-secretion did not show a distinct Th1-type or Th2-type pattern. The M protein dropped slightly in 3 out of 9 patients. We could show that DC-based Id vaccination is a feasible way of inducing specific T-cell responses in stage-I myeloma patients. Further trials are needed to increase the rate of responses and to define the role of DC-based vaccination in the era of new pharmacologic therapies.