Present Status and Problems on Molecular Targeted Therapy of Cancer

Numerous clinical trials of molecular targeted drugs for cancer have been conducted, with remarkable results for certain drugs and accumulation of "negative data" causing a hitch in the development plan for some other compounds. Five recent issues and problems of molecular targeted therapies were discussed critically. Drug discovery and effects against driver mutations (activating mutations) and problems: possibility for circumventing inherent and acquired resistance with the aim of achieving radical cure. Synthetic lethality: reasonable patient selection in individualized treatment strategy. Response rate and progression-free survival improvement with or without overall survival benefit and enhancement of toxicity in bevacizumab therapy: best endpoints for the evaluation of effect of antiangiogenic therapy. Negative data on small-molecule targeted therapy, primarily vascular endothelial growth factor tyrosine kinase inhibitors: loose GO or NO-GO decision criteria for further development of new compounds in early clinical trials. Effect of immunotherapy: difficulty to verify by proof of principle study. We are faced to many questions for the development of efficient personalized therapy. Accumulation of scientific global preclinical and clinical evidences is essential to use these new therapeutic modalities for the improvement of oncologic health care.