Humoral response to vaccination with interleukin-2-expressing allogeneic neuroblastoma cells after primary therapy.

Background: Immunotherapy using cytokine-expressing tumor cells has shown promise as an anticancer strategy. We have recently begun a trial of interleukin-2 (IL-2) gene-modified allogeneic neuroblastoma cells administered in a sequence of eight injections to patients with high-risk neuroblastoma following completion of primary therapy. Six patients to date have completed treatment.

Procedure: We examined humoral responses to the immunizing cell line and, when available, to the patients' autologous tumor cells using an in vitro binding assay.

Results: Five of six patients developed a rise in antitumor antibodies to the immunizing neuroblastoma cell line following vaccination. Two of these patients had autologous tumor available; both demonstrated a humoral response to these cells as well.

Conclusions: Our results demonstrate that vaccination with IL-2-expressing allogeneic tumor cells after intensive primary therapy can elicit a humoral response to the immunizing line. These antibodies are cross-reactive with the patients' own tumor cells in the two cases in which autologous cells were available. This suggests that different patients' tumors may share common antigens that can be exploited in immunotherapy strategies and supports the continued exploration of allogeneic tumor cells as tumor vaccines.