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Genetic Engineering of Tumor Cells
Many companies have effective vaccines for stimulating killer T lymphocytes. The
missing link is making good vaccines for helper T lymphocytes. That problem has
been solved by Antigen Express scientists, who developed means to suppress the
expression of a specifi c immunoregulatory protein (Ii). This protein can block anti-
gens from stimulating T helper cells. By inhibiting this protein, a whole range of
antigens from tumors can now be recognized by T helper cells, greatly boosting the
immune response to cancer.
Hybrid Cell Vaccination
The hybrid cell vaccination approach to cancer immune therapy aims at the induc-
tion of tumor-specifi c cytotoxic T cells and was developed for the following
purposes:
- To recruit and activate T cell help for the induction of tumor-specifi c cytotoxic
T cells - To correct defects in co-stimulatory signaling.
- To utilize a large number of unidentifi ed tumor-associated antigens
- For individualized therapy that can be applied instantly without long
preparation.
Hybridoma technology involves selection of long-term lines on the basis of their
resistance to anticancer drugs and according to specifi c functions desired. The
fusion partners are of the same tissue origin and are controlled by similar genetic
programs. The vaccines are irradiated prior to inoculation to ensure that the tumor
does not grow and spread in the body.
Clinical trials of hybrid cell vaccination have been performed in patients suffer-
ing from malignant melanoma or renal cell carcinoma and cases of complete
remission have been reported. The side effects seen in these trials were those of
induced immune response. Hybrid cell vaccination is a feasible strategy for the
treatment of cancer and is well suited for individualized therapy. Future trials will
establish the criteria for selection of patients and the malignancies suitable for this
therapy.
Personalized Peptide Cancer Vaccines
Following identifi cation of tumor associated antigens (TAA) in different tumor his-
totypes, many vaccination strategies have been investigated, including peptide-
based vaccines. Results of the fi rst decade of clinical experimentation, although
demonstrating the feasibility and the good toxicity profi le of this approach,
10 Personalized Therapy of Cancer