P2-11-08: Clinical Value of Combination Assay for Quantitative Determination of Cancer Biomarkers C2P and uPA/PAI-1 for Disease Recurrence Prediction of Early Breast Cancer Patients

[Background] C2P is an assay measuring specific activities (SA; kinase activity compensated by its protein expression) of cyclin-dependent kinases CDK1 and CDK2 by examining a small piece of fresh-frozen tumor tissue. We reported previously that the C2P risk score given by CDK1SA and CDK2SA is a potent prognostic factor in node-negative breast cancer patients. Likewise, a uPA/PAI-1 ELISA test (FEMTELLE®, American Diagnostica Inc. Stamford, CT) quantitatively determines uPA (urokinase-type plasminogen activator) and PAI-1 (plasminogen activator inhibitor type-1) antigen levels in tumor tissue extracts, to identify patients with high or low risk of disease recurrence of node-negative breast cancer patients. These cancer biomarkers are recommended by the ASCO at the highest level of evidence (LOE-1) for therapy decision making in node-negative breast cancer patients. From the biological point of view, the above two assays can be placed into two categories: tumor cell proliferation for C2P and tumor cell invasion for uPA/PAI-1. This fact led us to examine the concept of combination of the two assays to better select breast cancer patients at risk. [Results] Fifty-nine cases of frozen primary breast cancer tissues were subjected to the C2P assay in a blinded manner. Twenty-one cases (40%) were categorized into “high risk”, 7 cases (14%) into “intermediate risk”, and 24 cases (46%) into “low risk”. Seven cases were judged as “not informative”. The uPA/PAI-1 results and clinical information (26: recurrent cases, 30: non-recurrent cases, 1: stage IV, 2: unknown) were provided by the TUM tumor bank. uPA/PAI-1 risk categories of 36 cases (61%) were classified “high” and 23 cases (39%) categorized “low”. C2P and uPA/PAI-1 showed statistically significant correlation to histological grading (Pearson correlation coefficient; 0.45 and 0.40, respectively). No significant correlation was observed between C2P and uPA/PAI-1. By Kaplan-Meier analysis for disease-free survival, in cases treated with endocrine therapy only, both C2P and uPA/PAI-1 showed a reproducible trend to the respective claimed performances as prognostic factors. In the combination analysis of the two parameters, where low/low was judged as “low” and the others as “high”, 11 cases (24%) were categorized into “low” and 34 cases (76%) into “high”. The sensitivity and negative predictive value for disease recurrence were 90% (19/20) and 91% (10/11), respectively. Strong statistical significance was observed between the risk categories by the log-rank test; p=0.0089, and also by Cox proportional hazards regression analysis; HR=9.18, p=0.032. By multivariate analysis, also including tumor size and nodal status, the CP2 uPA/PAI-1 combination evolved as a significant, statistically independent parameter (HR: 6.51, p Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P2-11-08.