Targeting pediatric malignancies for T cell-mediated immune responses.

Successful immune targeting of malignancies hinges upon the ability to activate specific T-cell populations to recognize and attack tumor but spare normal vital tissues. Investigators in the field of tumor immunology are currently utilizing at least three distinct approaches toward this goal. In the first approach, molecular targets of cytolytic T cells which spontaneously develop in tumor-bearing patients have been identified and are subsequently used as immunogens in immunotherapy trials. Whereas this approach originally focused upon the identification of tumor antigens in the immune-responsive tumors malignant melanoma and renal cell carcinoma, it surprisingly led to the identification of a variety of molecules that are now known to be expressed in other common pediatric and adult tumors. In the second approach, tumor-specific molecules (eg, mutant p53 and chromosomal translocations) that have been identified in individual tumors during the study of neoplastic transformation are used as immunogens. Because chromosomal translocations are common in pediatric tumors, such targets may be of particular interest in pediatric oncology. In the third approach, immunization with whole tumor cell components is undertaken with the assumption that the most immunogenic molecules within the tumor will dominate the immune response induced. The benefits and limitations for each approach, particularly as it pertains to the development of immunotherapy for pediatric tumors, are discussed in this article.