A breaking study in the Annals of Oncology confirmed that a short course duration of adjuvant trastuzumab improved the adverse cardiotoxicity profile; however, it was still inferior to 1-year of therapy.
“Chemotherapy plus 1-year trastuzumab is the standard adjuvant treatment of HER2-positive breast cancer,” Pierfranco Conte, MD, of the Department of Surgery, Oncology and Gastroenterology, at theUniversity of Padova in Italy, and colleagues wrote. “The efficacy of less extended trastuzumab exposure is under investigation. The short-HER study was aimed to assess the non-inferiority of 9 weeks versus 1 year of adjuvant trastuzumab combined with chemotherapy.”
The researchers conducted a multicenter study of 1,254 patients with node-positive or, if node negative, with at least one risk, HER2-positive breast cancer. Study participants were randomly assigned to reciev either chemotherapy plus 1 year of trastuzumab or plus 9-weeks of trastuzumab. The primary endpoint of the study was to measure if the 9-week duration was non-inferior to 1-year of adjuvant therapy in terms of disease free survival. The researchers also measured cardiotoxicity as a secondary endpoint.
Study results showed that disease free survival was similar, but did not meet the non-inferiority margin. The researchers noted that the hazard ratio was 1.13 with the confidence interval slipping into the non-inferiority margin in the upper limits. A Bayesian analysis confirmed that the probability of 9-weeks of trastuzumab was non-inferior is 80%.
The researchers found that overall survival at 5-years was similar between the two study groups, at 95.2% in the 1-year group and 95.0% in the 9-week group.
Most notably, the researchers found that cardiac events were significantly reduced in the 9-week group compared to the 1-year group (P < .0001). They explained that this could inform treatment decisions for patients with high cardiac risk.
“This study failed to show the non-inferiority of a shorter trastuzumab administration. One-year trastuzumab remains the standard,” the reseachers concluded. “However, a 9-week administration decreases the risk of severe cardiac toxicity and can be an option for patients with cardiac events during treatment and for those with a low risk of relapse.”