Eligibility and response guidelines for phase II clinical trials in androgen-independent prostate cancer: Recommendations from the prostate-specific antigen working group

Purpose: Prostate-specific antigen (PSA) is a glycoprotein that is found al most exclusively in normal and neoplastic prostate cells. For patients with metastatic disease, changes in PSA will often antedate changes in bone sca n. Furthermore, many but not all investigators have observed an association between a decline in PSA levels of 50% or greater and survival. Since the majority of phase II clinical trials for patients with androgen-independent prostate cancer (AIPC) have used PSA as a marker, we believed it wets impo rtant for investigators to agree on definitions and values for a minimum se t of parameters for eligibility and PSA declines and to develop a common ap proach to outcome analysis and reporting. We held a consensus conference wi th 26 leading investigators in the field of AIPC to define these parameters . Result: We defined four patient groups: (1) progressive measurable disease, (2) progressive bone metastasis, (3) stable metastases and a rising PSA, a nd (4) rising PSA and no other evidence of metastatic disease. The purpose of determining the number of patients whose PSA level drops in a phase II t rial of AIPC is to guide the selection of agents for further testing and ph ase III trials. We propose that investigators report at a minimum a PSA dec line of at least 50% and this must be confirmed by a second PSA value 4 or more weeks later. patients may not demonstrate clinical or radiographic evi dence of disease progression during this time period. Some investigators ma y want to report additional measures of PSA changes (ie, 75% decline, 90% d ecline). Response duration and the time to PSA progression may also be impo rtant clinical end point. Conclusion: Through this consensus conference, we believe we have developed practical guidelines for using PSA as ct measurement of outcome. Furthermo re, the use of common standards is important as we determine which agents s hould progress to randomized trials which will use survival as an end point . (C) 1999 by American Society of Clinical Oncology.