Abstract #LB-269: MAP-tau expression is prognostic but not predictive for taxane response in metastatic breast cancer

INTRODUCTION: Taxanes are microtubule stabilizing agents and potent cytotoxic molecules recognized as highly effective chemotherapeutic agents. Varying response rates of 40-60%, depending on treatment setting, suggest the need for a clinical diagnostic with predictive value to determine patient sensitivity to taxane therapy. Microtubule associated proteins (MAPs) mediate polymerization and endogenously alter microtubule stabilization/destabilization. Recently, MAP-tau (Tau), a microtubule stabilizing protein, has been investigated as a useful predictive marker for taxane sensitivity. However, studies evaluating the prognostic and predictive value of MAP-tau have presented conflicting results. Here we measure Tau levels in a retrospective cohort and a prospective Taxane clinical trial to determine its prognostic and predictive value. METHODS: Tau protein expression levels were quantitatively assessed using the AQUA technology in two cohorts: a 480-case Yale-based retrospective collection and a 140-case clinical trial (TAX 307, a randomized clinical trial comparing FAC versus TAC treatment as first line chemotherapy for metastatic breast cancer). Tissue microarray and whole section MAP-tau scores were correlated with clinical and pathologic variables. RESULTS: Prognostic evaluation of the Yale cohort using univariate analysis and median score cutpoint indicated a direct correlation between high MAP-tau expression and overall survival (HR = 0.73, 95% confidence interval [CI] = 0.62-0.85; p Citation Information: In: Proc Am Assoc Cancer Res; 2009 Apr 18-22; Denver, CO. Philadelphia (PA): AACR; 2009. Abstract nr LB-269.