Assignment to 6 months of adjuvant trastuzumab was non-inferior to 12 months trastuzumab in women with HER2-positive, early breast cancer, according to the results of the PERSEPHONE trial presented at the 2018 ASCO Annual Meeting in Chicago, Illinois.1

“Six months compared with 12 months treatment reduces cardiac and other toxicities as well as costs both to patients and the health care system,” said Helena Margaret Earl, MD, of the University of Cambridge. “These exciting results mark the first steps to the reduction of treatment duration for many women with HER2-positive breast cancer.”

According to Dr Earl, more than a decade ago the results of several trials started showing the benefit of adjuvant trastuzumab in patients with HER2-postive early breast cancer.

Trastuzumab gained FDA approval based on the results of these trials, which assigned trastuzumab for a duration of 12 months. In 2006, the small FinHer study showed similar outcomes with just 9 weeks trastuzumab used concurrently with docetaxel upfront.

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The question remained if reduced duration trastuzumab would have similar outcomes. PERSEPHONE was designed to see if 6 months trastuzumab would have similar efficacy but with reduced toxicity and cost. The phase 3 trial included 4088 women who were randomly assigned to either 6 months or 12 months of trastuzumab. All patients had to have a clear indication for chemotherapy and no evidence of metastatic disease. Disease-free survival was the primary outcome.

With a median follow-up of 5.4 years, there was no difference in disease-free survival found between the two arms. Disease-free survival at 4 years was 89.8% in the 12-month arm and 89.4% in the 6-month arm (non-inferiority P < .01). A predefined subgroup analysis showed that among patients who underwent trastuzumab given concurrently with chemotherapy a 12-month duration seemed to be of more benefit.