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Oral presentation

Development of immunotherapy in cancer, Strategies of the EORTC:

Vaccination strategies are increasingly being tested in various neoplastic diseases, most frequently at this time in patients with melanoma, colorectal cancer, prostate cancer, and leukemias. Compounds used with the aim to elicit specific immune responses include synthetic peptides, truncated and full antigenic proteins, and a variety of nucleic acids, such as plasmid DANN, retrovirl vectors, and vaccinia and adeno-associated viruses. The primary aim of antigen-specific vaccination is to elicit specific T cell immunity. However, robust and reliable assay systems to monitor T cell immunity had to be developed in the previous years. A recent workshop of the Society of Biological Therapy, the NCI, and the FDA has summarized the current status of these assay systems. None of them is standard at this time, but recommendations for trial monitoring have been developed, and can be obtained through the society office (http://www.isbtc.org webcite).

The clinical trials at this point are mostly proof of concept trials, phase I trials, and early phase II trials. The trial methodology, however, is not standard, as the toxicity of the vaccines is minimal, and the dose-response curve is very wide. Thus the aim of phase I studies is to achieve a maximal immune response, and not to reach MTD. The aim of phase II trials in tumor-bearing patients can be clinical, however, as vaccines tend to move into adjuvant disease situations, the aim of phase II trials is more to achieve a high rate of patients with strong and persistent immunity, which is difficult to describe with current phase II statistics. Furthermore, the potency of various vaccine adjuvants has to be tested in these early clinical studies. Originally, adjuvants were compared in subsequent cohorts of patients with similar disease situation, however, the results of subsequent patient cohorts may not always be reliable. Therefore, more recent trials have been designed as randomized phase II studies to compare the characteristics of vaccine adjuvants, and this trial methodology would also be appropriate for comparative evaluation of different vaccine strategies.

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