PIK3CA and ERBB2 mutations were detected at incidences of 35.0% (148/420) and 6.2% (26/420), respectively. PIK3CA mutations were associated with decreased PFS (wt vs mut: HR=0.81; 95% CI 0.64–1.02; p=0.077)….PIK3CA mutations associate with decreased PFS for pts enrolled in the NALA trial. Higher HER2 protein expression associates with increased PFS in the overall study population, and a greater benefit from N+C vs. L+C.