between a newer and a ''best available" therapy has increased. For example, to statistically demonstrate the increased effectiveness of adding a new agent to an acute lymphocytic leukemia induction regimen, when the current remission induction rate is well over 90 percent, would take many hundreds of patients . . For some pediatric tumors, Phase 3 trials now may take as long as four years to complete. Compounding these challenges is the fact that many new agents are available, including a variety of biologics, cytokines, differentiating agents, monoclonal antibodies, molecular therapies, and gene therapy approaches.
A major concern is the paucity of adequately trained pediatric cancer pharmacologists. Currently, Phase 1 trials are done at approximately 50 centers throughout the United States. Only a handful of these centers have active pediatric cancer clinical pharmacology laboratories; even a smaller number are actually training individuals in cancer clinical pharmacology. In many cases the type of clinical pharmacology training given is not formalized and is not adequate for the variety of new, molecularly targeted agents that will require study in the future. The pediatric cancer pharmacologist in the 21st century must not only be mined in pediatric oncology and classical clinical pharmacology but should also have an appropriate grounding in molecular biology. Training of such individuals may be the greatest single challenge for the field.