PROGRESS WITH TUMOR VACCINES

Immunological treatment of malignant tumours is based on the inherent immunogenicity of tumours. Apart from some exceptions, however, tumours of humans are only weakly immunogenic. They induce an immune response that, after skin tests with autologous tumour cells, becomes primarily evident as sensitisation of T lymphocytes to different types of tumour-associated antigens. Active specific immunisation pursues the aim of amplifying this pre-existing sensitisation into an effective antitumour immune response. Besides adjuvants there are several ways of increasing the immunogenicity of tumour cells and soluble tumour-associated antigens. However, newly developed strategies to prepare tumour vaccines, such as transfection of tumour cells with the genes of immunological effector molecules or insertion of tumour-associated antigen genes into viral or mycobacterial vectors, may be more effective. Current clinical trials of active specific immunisation, still highly experimental, are focused especially on patients with malignant melanoma or colorectal carcinoma. Their results may nourish the hopes of clinicians, but cannot yet refute the objections of sceptics.