Dr. Martine Piccart-Gebhart presented results at the 2014 annual meeting of the American Society of Clinical Oncology showing that a combination treatment of Tykerb® (lapatinib) and Herceptin® (trastuzumab) offered no benefit in outcomes for early stage HER2-positive breast cancer patients.

Twenty to thirty percent of breast cancers overexpress (make too much of) a protein known as HER2. Overexpression of this protein leads to increased growth of cancer cells. Tykerb and Herceptin are treatments that target these HER2-positive cells and are generally administered after surgery to reduce the risk of relapse.

The ALTTO trial, begun in 2007, enrolled 8381 women in 44 countries with HER2-positive early breast cancer.  Patients were assigned to one of four treatment groups: Herceptin alone, Tykerb alone, Herceptin followed by Tykerb, or Herceptin plus Tykerb. Patients were treated with the regimens for 1 year. All patients were also receiving chemotherapy.

Researchers found that disease-free survival at 4 years did not improve when the concurrent combination therapy was compared to Herceptin alone. It was also true that the sequential administering of Herceptin and Tykerb versus Herceptin alone did not improve disease-free survival.

Researchers also reported that patients with the dual therapy when compared to Herceptin alone had higher rates of side effects such as diarrhea, rash, and problems with the liver and biliary tract.

Dr. Piccart-Gebhart reported that despite the disappointing results for the dual therapy, the results for the Herceptin alone group were encouraging. The 4-year disease-free survival rate was 86% and the overall survival rate was 94%.

Reference: Piccart-Gebhart, Martine J., et al. First results from the phase III ALTTO trial comparing one year of anti-HER2 therapy with lapatinib alone, trastuzumab alone, their sequence, or their combination in the adjuvant treatment of HER2-positive early breast cancer. J Clin Oncol 32:5s, 2014 (suppl; abstr LBA4).

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