CHICAGO — Neither adding lapatinib to trastuzumab plus weekly paclitaxel after an anthracycline nor the substitution of lapatinib for trastuzumab with weekly paclitaxel after an anthracycline was significantly superior to trastuzumab with regard to 5-year recurrence-free interval and overall survival in patients with operable, HER2-positive breast cancer.1
Previously reported findings have demonstrated that pathologic complete response rates were 52.5% with an anthracycline followed by weekly paclitaxel and trastuzumab, 53.2% for an anthracycline followed by weekly paclitaxel and lapatinib, and 62% for an anthracycline followed by weekly paclitaxel plus trastuzumab and lapatinib.
At the 2016 American Society of Clinical Oncology (ASCO) Annual Meeting, investigators reported results on planned secondary end points, which included 5-year recurrence-free interval and overall survival.
The 5-year recurrence-free interval rate was 90% for an anthracycline followed by weekly paclitaxel and trastuzumab plus lapatinib (HR, 0.66; 95% CI, 0.34-1.25; P=.33), 80.7% for an anthracycline followed by weekly paclitaxel and lapatinib (HR, 1.27; 95% CI, 0.74-2.2; P=.14), and 86.9% for an anthracycline followed by weekly paclitaxel plus trastuzumab.
“Exploratory analyses of recurrence-free interval by hormone status showed similar trends in patients with hormone receptor (HR)-negative and those with HR-positive tumors,” said lead investigator Andre Robidoux, MD, medical oncologist at Centre Hospitalier de l’Universite de Montreal in Canada.
Researchers found that the 5-year overall survival rates were 95.7% (HR, 0.63; 95% CI, 0.24-1.67; P=.55) with an anthracycline followed by weekly paclitaxel and trastuzumab plus lapatinib, 89.4% (HR, 1.52; 95% CI, 0.69-3.35; P=.11) with an anthracycline followed by weekly paclitaxel and lapatinib, and 94.5% with an anthracycline followed by weekly paclitaxel plus trastuzumab.
However, Dr Robidoux also noted that exploratory analyses suggest that the 3 treatment arms are different in long-term outcomes (P=.049 for recurrence-free interval and P=.07 for overall survival.
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The study further demonstrated that achievement of pathologic complete response was strongly associated with improved recurrence-free interval (P=.0009) and overall survival (P=.0004), with the association between pathologic complete response and recurrence-free interval varying across hormone receptor status.
“Pathologic complete response was a more informative prognostic marker for improved long-term outcomes in the estrogen receptor-negative/progesterone receptor-negative subset of patients with HER2-positive breast cancer,” Dr Robidoux explained.
- Robidoux A, Tang G, Rastogi P, et al. Evaluation of lapatinib as a component of neoadjuvant therapy for HER2+ operable breast cancer: 5-year outcomes of NSABP protocol B-41. J Clin Oncol. 2016; 34 (suppl; abstr 501).