Serum collagen fragments and outcomes in hormone receptor-positive metastatic breast cancer.

539Background: 4 extracellular matrix (ECM) protein fingerprints in serum were correlated with outcomes in a phase 3 randomized clinical trial of 2nd-line hormone receptor-positive metastatic breast cancer: C1M (MMP-2/-9/-13 degradation of type I collagen), C3M (MMP-9 degradation of type III collagen), C4M (MMP-9/-12 degradation type IV collagen), and PRO-C3(true type III collagen formation). Methods: The pretreatment serum bank from 155 trial patients was evaluated using ELISA assays for the 4 ECM protein fingerprints and then correlated with TTP and OS. Results: In univariate analysis for TTP using the ECM fingerprints: 1) on a continuous basis, higher PROC3 was significant for shorter TTP, but C1M, C3M and C4M were not; 2) on a categorical basis (75th percentile), elevated C1M and C3M were significant for shorter TTP, but C4M and PROC3 were not. For overall survival (OS) using the ECM protein fingerprints: 1) on a continuous basis, higher C1M, C4M, and PROC3 were associated with shorter OS, but C3M was...