One Year of Adjuvant Trastuzumab Remains Standard of Care

Richard Gelber, MD

Long-term follow-up of the HERA trial confirms that 1 year of adjuvant therapy with trastuzumab should remain the standard of care for treatment of women with HER2-positive (HER2+) invasive early breast cancer. HERA compared 1 year versus 2 years of trastuzumab versus observation alone in the adjuvant setting, and updated results failed to show a benefit for an additional year of therapy.

At a median follow-up of 8 years, sustained and significant improvement in disease-free survival (DFS) and overall survival (OS) was observed for 1 year of trastuzumab despite the fact that 50% of patients in the observation arm crossed over to trastuzumab.

“There is no evidence of long-term benefit of 2 years compared to 1 year of trastuzumab when administered as sequential treatment following chemotherapy,” stated senior author Richard Gelber, MD, of Dana-Farber Cancer Institute in Boston.

HERA was a one of the pivotal trials for registration of trastuzumab for 1 year as part of adjuvant therapy for HER2+ early breast cancer. This is the only trial to compare 1 year versus 2 years of trastuzumab, Gelber noted. The data presented October 1 at the 2012 ESMO Congress in Vienna is a second analysis at 8 years comparing 1 year of trastuzumab versus 2 years of trastuzumab versus observation alone.

The study included 5102 women with locally determined HER2+ invasive early breast cancer treated with surgery and adjuvant or neoadjuvant chemotherapy and radiation. HER2 status was confirmed by IHC3+ or FISH+ and patients with left ventricular ejection fraction of at least 55% were randomized as follows: 1698 patients to observation alone (allowed to switch to trastuzumab after ASCO 2005); 1703 patients to 1 year of trastuzumab for 1 year; and 1701 patients to 2 years at the same dose and schedule (i.e., 8 mg/kg — 6 mg/kg 3 weekly schedule).

Gelber explained that the small difference in DFS between the two treatment arms disappeared at 8 years, with both DFS curves merging at the later time point: DFS was 75.8% for 2 years of trastuzumab versus 76% for 1 year of trastuzumab.

“In 2005, we offered trastuzumab to all patients in the observation group; 50% received trastuzumab between 6 and 36 months after entering the trial,” he noted.

“The update at 8 years, even with 50% of patients in the observation group receiving trastuzumab, showed a 24% reduction in risk of recurrence for patients assigned trastuzumab over observation,” Dr. Gelber said.

“The OS benefit at 8 years for trastuzumab versus observation is sustained and robust over the long term,” he concluded.

Commenting on these updated results of HERA, Christoph Zielinski, MD, President of the Central European Cooperative Oncology Group, and Professor at the Medical University of Vienna, Austria, emphasized that these results of HERA, as well as 3-year follow-up of the PHARE trial (comparing 1 year of trastuzumab to 6 months of trastuzumab in the adjuvant setting), confirm that 1 year of adjuvant trastuzumab remains the standard of care for HER2+ breast cancer.

Goldhirsch A, Piccart M, Procter M, et al. HERA trial: 2 years versus 1 year of trastuzumab after adjuvant chemotherapy in women with HER2-positive early breast cancer at 8 years of median follow up. Presented at: European Society of Medical Oncology 2012 Congress; September 28 — October 2, 2012; Vienna, Austria. Abstract LBA 6.

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