Higher serum human epidermal growth factor 2 (sHER2) predicted greater progression-free survival (PFS) in patients with advanced breast cancer with lapatinib independent of tissue HER2 (tHER2), and high sHER2 was also independently prognostic for worse survival in patients who received nonlapatinib-containing therapies. This according to a study of sHER2 and tHER2 tissue from 1,902 patients randomly assigned to received lapatinib or control. Researchers found:
• Lapatinib had significant PFS benefit over control (HR=0.855), but not overall survival (HR=0.941).
• Lapatinib PFS benefit is independently predicted by higher sHER2 values and by positive tHER2.
• Within the tHER2-positive subpopulation (n=515), higher sHER2 values still independently predicted lapatinib PFS benefit.
• In control arms (n=936), higher sHER2 was associated with worse prognosis in multivariable analyses.
Citation: Lee CK, Davies L, Gebski VJ, et al. Serum human epidermal growth factor 2 extracellular domain as a predictive biomarker for lapatinib treatment efficacy in patients with advanced breast cancer. [Published online ahead of print January 25, 2016]. J Clin Oncol. doi: 10.1200/JCO.2015.62.4767.