Search for effective therapy against glioblastoma multiforme—clinical immunisation with autologous glioma cells transduced with the human interferon-γ gene

Abstract

Based upon earlier experimental work by our group, we have started a human immuno-gene therapy study. The goal is to study the effects of immunisation with autologous tumour cells expressing gene sequences for human interferon-γ. For more than two decades we have sought for efficient treatment against malignant gliomas. Our most successful treatment in the animal models is immuno-gene therapy where murine genes for the cytokines IFN-γ, IL-7 and B7-1 were chosen for their ability to stimulate different stages of the pathway for cytotoxic T lymphocyte (CTL) activation. Rats of the syngeneic inbred strain Fischer 344 had rat glioma cells of the N32 line inoculated in the right caudate nucleus, and 1 or 3 days later N32 cells transfected with either IFN-γ, IL-7 or B7-1 genes were injected subcutaneously (and in some studies intraperitoneally). This treatment was repeated three to four times with 7- to 14-day interval and resulted in significantly improved survival compared with treatment with wild-type rat glioma cells (e.g. not transfected with the cytokine genes). The continued work concentrated on treatment with IFN-γ secreting tumour cells of both the N32 line and also a newly developed ENU-induced rat glioma cell line called N29. This work proved the effectiveness of the technique. Cure was achieved in 72% of the animals treated with the IFN-γ cells. Tumour-infiltrating leukocytes from N32-IFN-γ-immunised animals showed a significantly stronger infiltration by CD 8+ T-cells, significantly more NK cells, and an increased number of CD25-expressing T-cells. These results confirmed the possible usefulness of IFN-γ-transfected tumour cells in the immune-therapy of rat brain tumours. The animal experiments have motivated us to start a human immuno-gene therapy study including 20 patients with glioblastoma multiforme (GBM), where >80% of the tumour can be surgically removed. The goal is to ascertain whether immunisation with autologous tumour cells expressing gene sequences for human interferon-γ is safe for the patients, gives rise to an immunological response, and adds any beneficial effect to conventional therapy (tumour growth, prolonged survival). Hitherto, nine patients have been included in the study, two of which have received 6 and 10 immunisations, respectively. Two patients have died from their disease before cells have been ready for immunisation; in two cases no malignant cells have appeared in the cell cultures and three patients are ready to start their immunisation shortly. The immunisation takes place in the dermis of the upper arm. Seven days after each immunisation, a skin biopsy is taken from the centre of one of the injection sites. The composition of the cellular infiltration in the skin is studied by markers for T lymphocytes (CD3); helper cells, subset of T cells (CD4); killer cells, subset of T cells (CD8); natural killer cells (CD16) and B lymphocytes, B cells (CD20). Also the expression of cytokines for functional T cell subsets are studied: IL-2, IL-4, IL-10, IL-12, IL-18, TNF-α and IF-γ and TGF-β 1,2 and 3. Peripheral blood is sampled both before and after operation and also after each immunisation event. Co-culture of this blood with tumour cells from the patient allows for a selection of T-cells that can recognise tumour-specific antigens. The results from the first human treatments are presented.