Surrogacy Case Study: Prostate Specific Antigen (PSA ... - Isped
Surrogacy Case Study: Prostate Specific Antigen (PSA ... - Isped
Surrogacy Case Study: Prostate Specific Antigen (PSA ... - Isped
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Proposed strategy for preparing the use of a marker<br />
in phase II<br />
• Solid preclinical and clinical data are needed about the<br />
drug’s effect on <strong>PSA</strong>, it’s shape, it’s timing (remember<br />
Calcitriol, APC 8501, Suramin..)<br />
• Neo-adjuvant studies are required to document<br />
• The effect of the new drug (alone or in the intended<br />
combination) on the marker<br />
• Correlation between changes in the marker and observed<br />
changes on the tumor<br />
• Without such information, even phase II trials with a markerbased<br />
endpoint, be it response or PFS, are a very risky<br />
gamble<br />
• New guidelines (PCWG2, JCO 08) move away from the <strong>PSA</strong><br />
response endpoint<br />
• Research is being done to make bone metastases changes<br />
measurable to use them as phase II endpoint
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