Cancer immunotherapy products: regulatory aspects in the European Union.

Active immunotherapy products (widely known as "cancer vaccines") are products intended to stimulate an immune response to mediate tumor destruction or reduce the progression of disease in patients where cancer has been diagnosed. Some quality attributes of these products are very difficult to characterize or present a high variability (especially if they are for autologous use), further complicating the interpretation of some of the clinical data. Furthermore, questions arise in the evaluation of efficacy and safety data in comparison with current chemical or biological treatments for the same indications. Some of these aspects are discussed in this paper in relationship with the regulatory requirements in the European Union and as applied to two recently assessed medicinal products, Oncophage and Provenge, both considered therapeutic "cancer vaccines" for renal cell carcinoma and prostate cancer, respectively.