Prostate-specific antigen (PSA) is a 34-kDa tissue kallikrein glycoprotein that is expressed in normal prostate tissue and prostate cancer. This androgen-regulated serine protease aids in the liquefaction of seminal coagulum to allow sperm to become more motile. Normally, PSA is secreted into the prostatic ducts; however, in prostate cancer the disordered glandular architecture causes increased amounts of PSA to diffuse into the serum. PSA measurements serve as screening and prognostic markers for prostate cancer. PSA is also the most sensitive and widely used marker of response to therapy in patients with prostate cancer. PSA has been shown to be immunogenic. It is essentially expressed only in the prostate, therefore therapeutic targeting of PSA may be beneficial. Because it is secreted and not membrane bound, antibody approaches hold no utility. However T-cell based approaches such as therapeutic vaccines have been developed and have shown safety and preliminary evidence of efficacy in randomized studies. A definitive phase III study of PSA-TRICOM (PROSTVAC) may have results as early as the end of 2016.
KeywordsAmerican Society for Radiation Oncology (ASTRO) Prostate-specific antigen (PSA) Androgen-deprivation therapy Assessment Biochemical failure Biology Clinical studies Preclinical models Pretreatment Risk stratification and prognosis Screening tests Therapeutics Tumor-associated antigens (TAAs)
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