EVALUATION OF BIOMARKERS OF SURVIVAL RESPONSE IN HORMONE-REFRACTORY PROSTATE-CANCER PATIENTS TREATED WITH SURAMIN

Hormone-refractory prostate cancer (HRPC) patients often have nonmeasu rable disease. In such patients, predictive biomarkers other than tumo r response may be required to compare therapeutic effects. We examined the predictive value for survival of various clinical and laboratory parameters, including prostate-specific antigen (PSA), in HRPC patient s treated with suramin, Data from 103 HRPC patients were analyzed usin g various survival analyses, the likelihood ratio approach, and logist ic regression analyses. When pretreatment factors, percentage decrease in PSA at 4 weeks from start of treatment (Delta PSA), and updated su rvival data were fit by a multivariate Cox proportional hazards model, acid phosphatase, lactate dehydrogenase, and Delta PSA were significa nt, with risk ratios close to 1, There was a decrease in likelihood ra tio with increasing Delta PSA. A logistic regression model was develop ed to predict the probability of <1 year of survival from the start of treatment. Hemoglobin and Delta PSA were found to be significant vari ables, However, in view of the complexities involving the relationship between PSA expression and prostate cancer growth and possible select ive effect of treatment on PSA, further prospective testing is necessa ry. Therefore, Delta PSA cannot necessarily be used as a biomarker for survival response in individual patients during the evaluation of the therapeutic response of HRPC to new antineoplastic drugs.