[Molecular-targeted therapy for prostate cancer]

Once, prostate cancer becomes hormone-refractory, there are only a few effective therapies such as docetaxel-based chemotherapies. Several molecular targeted therapeutic drugs have been tested for prostate cancer such as endothelin-A receptor antagonist, endothelial growth factor receptor or platelet derived growth factor receptor inhibitor. Nuclear factor kappa B (NFkappaB) is a key molecule for the growth of prostate cancer. Therefore, NFkappaB can be a good target for the therapy. In fact, a couple of NFkappaB inhibitors have been clinically or pre-clinically tested. Among them, Bortezomib and thalidomide showed little clinical efficacy as a single therapeutic agent. However, these drugs exerted clinical benefits to some extent when used with other chemotherapeutic drugs. Dexamethasone is also an NFkappaB inhibitor. Its clinical efficacy is through suppressing the adrenal androgen level. Besides adrenal androgen blockade, dexamethasone suppresses the growth of prostate cancer via NFkappaB inactivation, and also via the inhibition of interleukin-6 production which is reportedly important for the growth of prostate cancer. One of the clinical benefits of dexamethasone treatment is the improvement in anemia.