Monitoring antitumour immune response during immunotherapy of cancer: why and how?

Cancer remains one of the most important public health concerns facing us today. Despite recent therapeutic developments, conventional therapies have provided only limited success in the management of patients with advanced disease. The recent discovery of tumour-associated antigens has led to a strong interest in immunotherapy as an alternative or adjuvant cancer treatment modality. Despite the expanding volumes of literature on this form of therapy confirming its strong anti-neoplastic effects in animals, much still remains to be elucidated with respect to its clinical applicability and effectiveness in human subjects. Clinical trials evaluating a wide variety of immunotherapeutic approaches in cancer patients are currently underway throughout the world and many have yielded promising preliminary results. In order to reach a better understanding of this potentially powerful therapeutic tool in a timely fashion, a methodical, multi-institutional approach is indispensable. All patients undergoing treatment should be monitored closely in order to correlate specific therapy-induced anti-tumour responses with clinical outcomes. This article provides a brief overview of specific assays currently used to monitor immune responses in these patients. Special emphasis is placed on the theory behind these tests and specific examples from the literature are provided.