Breast Cancer Coverage from Every Angle

Phase III Trial of Triplet Regimen for HER2-Positive Metastatic Breast Cancer

By: Celeste L. Dixon
Posted: Wednesday, August 5, 2020

Based on the findings of a randomized phase III trial testing a new first-line role for lapatinib in HER2-positive invasive metastatic breast cancer—combining it with paclitaxel and trastuzumab (THL)—the progression-free survival results trended toward, but did not reach, statistical significance. Thus, Bryan Hennessy, MD, of Beaumont Hospital, Dublin, Ireland, and colleagues cautiously concluded that the outcome “may indicate the addition of a HER2-targeted tyrosine kinase inhibitor to trastuzumab-containing chemotherapy regimens warrants [further] investigation” in this patient population. These findings were presented during the 2020 American Association for Cancer Research (AACR) Virtual Annual Virtual Meeting I (Abstract C212).

Progression-free survival and overall survival were the primary and secondary outcomes, respectively, of the international study, ICORG (CTRIAL-IE) 11-10, included 75 patients. These patients were randomly assigned 1:1 to receive the doublet paclitaxel plus trastuzumab or the doublet plus lapatinib. The authors noted that target accrual was not met due to standard of care changes in the middle of the study. 

The median progression-free survival in the analysis group of 65 patients was 24.0 months with THL versus 19.3 months with paclitaxel plus trastuzumab (P = .601). The median overall survival analysis, including 69 patients, offered no improvement with the triplet over the doublet (45.6 months vs. 53.8 months; P = .891).

Adding lapatinib to the doublet regimen was “tolerated, with gastrointestinal toxicity emerging as the predominant adverse event,” noted Dr. Hennessy and colleagues. Diarrhea occurred in 88% and 42% of the triplet and doublet arms, respectively (P < .0001). More grade 3 or 4 adverse events occurred with the triplet regimen as well (61.8% vs. 50.0%; P = .322).

 Disclosure: For disclosures of the study authors, visit

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