Lapatinib is associated with shorter progression-free survival (PFS) and more toxicity in patients with human epidermal growth factor receptor 2 (HER2)-positive breast cancer compared with trastuzumab, according to a recent study published online ahead of print in the Journal of Clinical Oncology.

As part of the MA.31 trial which compared first-line anti-HER2 therapy for both of these treatment modalities, researchers led by Karen A. Gelmon, MD, FRCPC, of the British Columbia Cancer Agency studied 652 patients from July 2008 to December 2011. Primary endpoint was intent-to-treat PFS, and 537 had centrally confirmed HER2-positive tumors.

Dr. Gelmon and fellow authors found that median intent-to-treat PFS was 9 months with lapatinib and 11.3 with trastuzumab. In those with centrally confirmed HER2-positive tumors, median PFS was 9.1 months with lapatinib and 13.6 months with trastuzumab.

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In addition, they found more instances of grade 3 or 4 diarrhea and rash in patients treated with lapatinib.

“As first-line therapy for HER2-positive metastatic breast cancer, lapatinib combined with taxane was associated with shorter PFS and more toxicity compared with trastuzumab combined with taxane,” they concluded.


  1. Gelmon, Karen A., et al. “Lapatinib or Trastuzumab Plus Taxane Therapy for Human Epidermal Growth Factor Receptor 2–Positive Advanced Breast Cancer: Final Results of NCIC CTG MA.31.” Journal of Clinical Oncology. doi: 10.1200/JCO.2014.56.9590. [epub ahead of print]. March 16, 2015.