Vaccination of recurrent glioma patients with tumour lysate-pulsed dendritic cells elicits immune responses: results of a clinical phase I/II trial

Immunotherapy of intracranial G422 glioblastoma with dendritic cells pulsed with tumor extract or RNA

OBJECTIVE

To investigate the anti-tumor efficacy of dendritic cell (DC)-based vaccines pulsed with tumor extracts or RNA in a mouse model of intracranial G422 glioblastoma.

METHODS

Bone marrow-derived DCs were pulsed ex vivo with tumor extracts or RNA. Ninety female mice harboring 4-day-old intracranial G422 glioblastomas and 126 normal mice were treated with three spaced one week apart subcutaneous injections either with PBS, unpulsed DCs, G422 tumor extracts, RNA, DCs pulsed with G422 tumor extracts (DC/extract) or with RNA (DC/RNA). Seven days after the third immunization of normal mice, the spleens of 36 of them were harvested for cytotoxic T lyphocyte (CTL) assays and the others were challenged in the brain with G422 tumor cells. All the treated mice were followed for survival. Some mice brains were removed and examined pathologically when they died.

RESULTS

Immunization using DC/extract or DC/RNA significantly induced G422-specific CTL responses compared with control groups (P<0.01). Vaccination with DC/extract or DC/RNA, either prior to G422 tumor challenge or in tumor-harboring mice, significantly prolonged survival compared with other control groups (P<0.01).

CONCLUSION

DCs pulsed with tumor extracts or RNA derived from autologous tumors has potential antitumor effects via activation of cell-mediated immunity. Our results suggest a useful therapeutic strategy against gliomas.

Dendritic Cell-Based Immunotherapy of Malignant Gliomas

The failure of conventional treatment modalities for gliomas, in spite of tremendous progress in research in the past two decades, has led to increasing interest in alternative treatment strategies, including immunotherapy. It has become evident that vaccination with dendritic cells (DC), designed to express tumor antigens, is a potent strategy to elicit anti-tumor immune response in both pre-clinical and clinical settings. Various methods have been applied in order to induce DC to express tumor antigens including: pulsing with isolated tumor peptides or whole tumor lysate; fusion with tumor cells; and pulsing with apoptotic tumor cells. Herein, we review the recent progress in DC biology with regard to tumor immunity and discuss current DC-based strategies and future prospects in immunotherapy for malignant gliomas.

Malignant gliomas

Malignant gliomas are the most common type of primary brain tumor. Although therapy for patients with these tumors remains limited, there has been important progress recently. In this review, some of these advances are discussed, with an emphasis on targeted molecular therapies.

Molecular imaging of cell-based therapies

This article focuses on molecular imaging of novel cell-based therapies, particularly stem cell therapies and the adoptive transfer of immunocytes. The animal models,potential clinical applications, and likely future prospects of these therapies are discussed in the context of imaging.

Vaccination with tumor cell lysate-pulsed dendritic cells augments the effect ofIFN-? gene therapy for malignant glioma in an experimental mouse intracranial glioma

Interferon-beta (IFN-beta) has been used as an antitumor drug against human glioma, melanoma and medulloblastoma since the 1980s. Recently, we developed a new gene therapy using the IFN-beta gene against malignant gliomas and then began clinical trials in 2000. Since stimulation of immune system was one mechanism of antitumor effect induced by IFN-beta gene therapy, we hypothesized that combination of IFN-beta gene therapy with immunotherapy might increase its effectiveness. In the present study, we tested whether combination therapy with IFN-beta gene therapy and immunotherapy using tumor cell lysate-pulsed dendritic cells (DCs) would increase the efficacy of IFN-beta gene therapy. In an experimental mouse intracranial glioma (GL261), which cannot be cured by either IFN-beta gene therapy or DC immunotherapy alone, IFN-beta gene therapy following DC immunotherapy resulted in a significant prolongation in survival of the mice. Moreover, when this combination was performed twice, 50% of treated mice survived longer than 100 days. Considering these results, this combination therapy may be one promising candidate for glioma therapy in the near future.