Tumor-targeted immune complex formation: effects on myeloid cell activation and tumor-directed immune cell migration

Complement in cancer and cancer immunotherapy

Recently, there has been an increase of interest in the use of biological or immune-based therapies for patients with malignancies. This has been informed by the deeper understanding of the crosstalk between the host immune system and malignant tumours, as well as the potential advantages of immunotherapy-high specificity and less toxicity compared to standard approaches. The particular emphasis of this article is on the role of the complement system in tumour growth and antibody-based cancer immunotherapy. The functional consequences from overexpression of complement regulators by tumours and the development of strategies for overcoming this are discussed in detail. This review discusses these issues with a view to inspiring the development of new agents that could be useful for the treatment of cancer.

Targeted immunotherapy of cancer: development of antibody-induced cellular immunity

Although immunotherapy of cancer encompasses a large variety of distinct protocols, virtually all therapeutic strategies require the enabling/training of the immune system to distinguish tumour tissue from healthy tissue. In the case of antibody-based therapies, specificity obviously arises from the selectivity of the antibodies for tumour antigens, and tumour cell death derives from either direct cytotoxicity of the antibody or antibody-dependent cellular cytotoxicity. However, even when both of the above killing mechanisms are simultaneously active, we suggest that antibody-based immunotherapies may fall far short of their full potential. In this editorial, we first summarize the mechanisms by which current antibody-based therapies mediate cancer cell removal, and then propose two strategies by which this class of immunotherapies might be further improved. These suggested improvements involve the decoration of tumour cell surfaces with foreign haptens against which an endogenous humoral immune response can be mounted and the recruitment of the cellular arm of the immune system in an antibody-dependent process.