HER2-Positive Breast Cancer: 10-Year Paclitaxel and Trastuzumab Survival

In a recent study, published in The Lancet Oncology, researchers presented 10-year outcomes of patients with small, lymph node-negative, HER2-positive breast cancer who underwent adjuvant paclitaxel and trastuzumab treatment. They also evaluated the HER2DX genomic tool for its ability to accurately predict patient prognosis.

The study’s lead author, Sara M Tolaney, MD, reported that adjuvant paclitaxel and trastuzumab was a reasonable standard of care for this population based on 10-year survival analysis of the open-label, single-arm, phase 2 APT trial. The authors further noted that the HER2DX tool might have the potential to refine prognoses in patients with HER2-positive breast cancer.

Paclitaxel & Trastuzumab in HER2-Positive Breast Cancer

Between October 29, 2007 and September 3, 2010, a total of 406 patients in the APT study received intravenous 80 mg/m² paclitaxel plus loading and maintenance doses of 4 mg/kg and 2 mg/kg trastuzumab, respectively, each week for 12 weeks. Trastuzumab was then extended for 40 weeks at doses of 2 mg/kg weekly or 6 mg/kg once every 3 weeks.

The cohort was 99.8% female (one male patient), 86.2% White, 6.9% Black or African American, and had a mean age of 55±10.5 years at enrollment. A total of 272 (67.0%) had hormone receptor-positive disease. The primary end point of the initial trial was 3-year invasive disease-free survival.

This analysis was performed after a median follow-up of 10.8 years (interquartile range, 7.1-11.4). Across all 406 patients with HER2-positive breast cancer, the team identified 31 invasive disease-free survival events; of these, 6 (19.4%) were locoregional ipsilateral recurrences, 9 (29.0%) were new contralateral breast cancers, 6 (19.4%) were distinct recurrences, and 10 (32.3%) were all-cause mortalities.

Dr. Tolaney and colleagues calculated the following 10-year survival outcomes in the APT population:

• Invasive disease-free survival: 91.3% (95% CI, 88.3-94.4)
• Recurrence-free interval: 96.3% (95% CI, 94.3-98.3)
• Overall survival: 94.3% (95% CI, 91.8-96.8)
• Breast cancer-specific survival: 98.8% (95% CI, 97.6-100)

In addition, the researchers noted that continuous risk scores generated by the HER2DX tool were significantly associated with invasive disease-free survival (hazard ratio [HR] per 10-unit increment, 1.24; 95% CI, 1.00-1.52; P=.047) and recurrence-free interval (HR, 1.45; 95% CI, 1.09-1.93; P=.011).

Ultimately, the study’s authors summarized that “adjuvant paclitaxel and trastuzumab is a reasonable treatment standard for patients with small, node-negative, HER2-positive breast cancer.”

Related: HD201 Versus Trastuzumab in ERBB2-Positive Breast Cancer