ASCO 2018 Preview: Duration of Adjuvant Trastuzumab in HER2-Positive Early Breast Cancer
Posted: Thursday, May 17, 2018
The rate of disease-free survival in women with HER2-positive early breast cancer treated with adjuvant trastuzumab appears to be similar whether they are treated for 6 months or 12 months, according to the results of Persephone, a phase III noninferiority trial. The research, led by Helena Earl, MBBS, PhD, FRCP, of the University of Cambridge, United Kingdom, also revealed that cardiac and other toxicities were significantly lower in patients receiving the shorter treatment, supporting a reduction of standard trastuzumab to 6 months. The study will be presented at the 2018 American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago (Abstract 506).
“By reducing [trastuzumab] by half, [the researchers] were able to cut down on the number of people who had to stop the treatment by half, and we anticipate this will have an effect on cost as well,” stated ASCO President Bruce E. Johnson, MD, FASCO, during an ASCO press briefing.
The international trial randomized 4,088 patients 1:1 to receive either 6 or 12 months of treatment with adjuvant trastuzumab. Participants were stratified by estrogen receptor status, chemotherapy type, and the timing of chemotherapy and trastuzumab administration. The study was powered to assess the noninferiority of 6 months of treatment (5% 1-sided significance, 85% power), with noninferiority defined as “no worse than 3%” below the 12-month arm’s assumed 80% 4-year disease-free survival.
At a median follow-up of 4.9 years, the 4-year rate of disease-free survival in both arms was 89%. The calculated hazard ratio (HR) was 1.05, significantly lower than the HR noninferiority limit of 1.29, which demonstrated the noninferiority of 6-month trastuzumab (1-sided P = .01). The rate of overall survival was also similar in both groups. Cardiac events requiring treatment discontinuation were cut in half in women receiving 6 months compared with 12 months of treatment (4% vs. 8%, P < .0001).
