Trastuzumab Regimens Offer Long-term Survival Advantages in HER2+ Breast Cancer

SAN ANTONIO—Trastuzumab-containing chemotherapy regimens offer superior survival to in HER2-positive early breast cancer, confirm 10-year follow-up final safety and efficacy data from the phase 3 BCIRG 006 trial, presented at the 2015 San Antonio Breast Cancer Symposium.¹

“At 10 years follow-up, disease-free survival and overall survival show a sustained and significant efficacy advantage of AC-TH and TCH over a non-trastuzumab regimen, AC-T,” reported lead author Dennis J. Slamon, MD, of the University of California, Los Angeles.

“The study showed this sustained efficacy benefits for both trastuzumab-based regimens, TCH and AC-TH, after 10 years of follow-up,” he said.

“The intent of the BCIRG-006 study was to assess the relative benefit and safety of 2 trastuzumab-based regimens compared to a then standard (non-trastuzumab) regimen in the adjuvant treatment of early HER2-positive breast cancer,” Dr Slamon said.

During 2001 to 2004, 3222 women with HER2-positive breast cancer with axillary node-positive or high-risk node-negative disease were stratified by node and hormone-receptor status, and randomly assigned to one of three regimens: AC-T (4 cycles of doxorubicin and cyclophosphamide [60/600 mg/m²] followed by 4 cycles of docetaxel) vs AC-TH (4 cycles of doxorubicin and cyclophosphamide [60/600 mg/m²] followed by 4 cycles of docetaxel [100 mg/m²] and 1 year of trastuzumab) vs TCH (6 cycles of docetaxel 75 mg/m² and carboplatin, and 1 year of trastuzumab).

At a median follow-up of 10.3 years, disease free survival rates for AC-T, AC-TH and TCH were: 67.9%, 74.6%, and 73.0%, (AC-TH vs AC-T: hazard ratio [HR] 0.72; 95% CI: 0.61-0.85; P < .0001; TCH vs AC-T: HR 0.77; 95% CI: 0.65-0.90; P = .0011), Dr Slamon reported.

Overall survival rates for AC-T, AC-TH and TCH were: 78.7%, 85.9%, and 83.3%, respectively. (AC-TH vs AC-T: HR 0.63; 95% CI: 0.51-0.79; P < .0001; TCH vs AC-T: HR 0.76; 95% CI: 0.62-0.93; P = .0075).

There was not a statistically significant difference in survival rates between the trastuzumab-containing regimens. However, the AC-TH group saw 5 times more cases of congestive heart failure than TCH (2.0% vs 0.4%; AC-T: 0.8%), Dr Slamon noted.

“Since its approval, the only major safety concern with trastuzumab has been its potential impact on cardiac function,” said Dr Slamon. “The TCH regimen essentially eliminates this safety concern by significantly reducing the incidence of congestive heart failure and/or cardiac dysfunction that is seen when trastuzumab is used with anthracyclines.”

Reference

1. Slamon DJ, Eiermann W, Robert NJ, et al. Ten year follow-up of BCIRG-006 comparing doxorubicin plus cyclophosphamide followed by docetaxel (AC→T) with doxorubicin plus cyclophosphamide followed by docetaxel and trastuzumab (AC→TH) with docetaxel, carboplatin and trastuzumab (TCH) in HER2+ early breast cancer. Oral presentation at: San Antonio Breast Cancer Symposium 2015; December 11, 2015; San Antonio, TX.