Plasma matrix metalloproteinases 7 and 9 in patients with metastatic breast cancer treated with marimastat or placebo: Eastern cooperative oncology group trial E2196

Background: The purpose of this study was to evaluate the prognostic and predictive utility of measuring plasma levels of matrix metalloproteinase (MMP)-7 and MMP-9 in patients with metastatic breast cancer (MBC) treated with the oral MMP inhibitor (MMPI) marimastat or a placebo. Patients and Methods: We measured plasma levels of MMP-7 and MMP-9 using an enzyme-linked immunoassay method in 140 evaluable patients with MBC enrolled on a multicenter clinical trial that compared the MMPI marimastat with placebo. Specimens were collected after completion of first-line chemotherapy in patients who had responding or stable disease and 3, 6, and 12 months after initiation of marimastat (10 mg orally twice daily) or placebo. Results: Baseline plasma MMP-7 and MMP-9 levels did not correlate with each other or with progression-free or overall survival. In addition, serial evaluation of plasma MMP-7 and MMP-9 levels revealed no significant changes over time in the marimastat or placebo groups or any correlation with trough plasma marimastat level. Conclusion: We conclude that measurement of plasma MMP-7 or MMP-9 levels, as performed in our trial, was not a useful prognostic or predictive factor in patients with MBC or in patients treated with an MMPI.