Niikura N, et al. - This large, multicenter retrospective study gauged the long-term outcomes for patients with a durable response to trastuzumab. After the interruption of trastuzumab therapy, some patients showed no evidence of disease. While awaiting a global collaborative effort for a randomized trial, experts suggested to cautiously explore discontinuation of maintenance trastuzumab in this patient population after a limited time.

Methods

• The data of patients diagnosed with HER2 (human epidermal growth factor receptor 2) -positive metastatic breast cancer who received trastuzumab for more than 2 years as the first-line treatment had been retrospectively evaluated.
• This analysis incorporated patients diagnosed between April 1, 2001 and December 31, 2014 at 19 institutions in Japan.
• 16 were excluded and 108 were evaluated, from 124 potential subjects.

Results

• As per observations, the median follow-up length was 7.7 years.
• This study reported disease progression in 44/108 (40.7%) patients and reported death of 13/108 (12%) patients.
• Moreover, the median progression-free survival was 11.2 years, and as more than 80% of patients were alive 10 years after metastatic breast cancer diagnosis.
• 57 achieved a clinical complete response, among the 108 patients.
• It was reported that trastuzumab therapy was interrupted for 27 (47.4%) of these patients (based on the doctor’s recommendation for 19 patients, owing to adverse events for 4 patients, owing to unknown reasons for 3 patients, and at the request of 1 patient).
• Findings indicated disease progression in 4 of the 27 patients after the interruption of trastuzumab treatment.
• For all 27 patients, the median duration of trastuzumab therapy was 5.1 years (0.9–9.3 years).