Idiotype vaccination using dendritic cells after autologous peripheral blood progenitor cell transplantation for multiple myeloma

The idiotype (Id) determinants on the multiple myeloma immunoglobulin can s erve as rumor-specific antigens. An anti-Id immune response may stem the gr owth of the malignant clone. We report on 26 patients treated at our instit ution with high-dose chemotherapy and peripheral blood progenitor cell tran splantation (PBPCT) and vaccinated with the Id protein. The patients receiv ed chemotherapy and PBPCT to establish a minimal residual disease state. Af ter high-dose therapy, the patients received a series of monthly immunizati ons consisting of 2 intravenous infusions of dendritic cells (DCs) pulsed w ith either Id protein or Id coupled with keyhole limpet hemocyanin (KLH) as an immunogenic carrier protein, followed by subcutaneous boosts of Id-KLH conjugates. DCs were obtained in all patients from a leukapheresis product 3 to 9 months after PBPCT. Patients were observed for toxicity, immune resp onses, and tumor status. The DC infusions and the administration of Id-KLH boosts were well tolerated, with patients experiencing only minor and trans ient side effects, Of the patients, 24 of 26 generated a KLH-specific cellu lar proliferative immune response. Only 4 patients developed an Id-specific proliferative immune response. Three of these immune responders were in co mplete remission at the time of vaccination. A total of 17 patients are ali ve at a median follow-up of 30 months after transplantation. Id vaccination with autologous DCs is feasible for myeloma patients after transplantation . Id-specific cellular responses can be induced in patients who are in comp lete remission, Further studies are needed to increase the rate of anti-Id immune responses in patients who do not achieve complete remission.