Retrospective analysis of HER2 therapy interruption in patients responding to the treatment in metastatic HER2+ breast cancer

Introduction

Human epidermal growth factor receptor 2 (HER2)-targeted-therapy regimens can lead to prolonged tumour responses in metastatic HER2+ breast cancer. Clinical trials have concerned use of HER2-targeted agents until disease progression, but it is unknown whether the therapy can be interrupted in cases of a good response.

Methods

Single institute, retrospective collection of data on patients with HER2+ metastatic breast cancer (n=68) was carried out through a pharmacy search for patients who had received trastuzumab in 2006–2014. Clinical and pathological factors, treatment history and survival data were collected from patient records.

Results

Median survival in metastatic disease (all patients) was 32 months and survival times were dramatically different in patients with and without trastuzumab as adjuvant or primary metastatic disease (median 16, 77 and 35 months, respectively; p=0.0004). More importantly, HER2 therapy was intentionally interrupted in 21 responding patients, and these patients experienced long HER2-therapy-free intervals (median 51 months), with excellent long-term survival. A lack of previous adjuvant trastuzumab was the only statistically significant factor predictive of HER2 therapy interruption.

Conclusions

These results from our retrospective study show that HER2 therapy interruption in patients with metastatic HER2+ breast cancer, who have responded to the therapy, is associated with low risk of rapid disease progression. Study suggests that therapy interruption in cases of response and reinitiation in progression is feasible.

Long-term tumor remission under trastuzumab treatment for HER2 positive metastatic breast cancer - results from the HER-OS patient registry

Background

In this study, we examined patients who had non-progressive disease for at least 2 years after diagnosis of inoperable locoregional recurrent or metastatic breast cancer under continuous trastuzumab treatment. Our primary goal was to assess the long-term outcome of patients with durable response to trastuzumab.

Methods

268 patients with HER2-positive inoperable locally recurrent or metastatic breast cancer and non-progressive disease for at least 2 years under trastuzumab treatment were documented retrospectively or prospectively in the HER-OS registry, an online documentation tool, between December 2006 and September 2010 by 71 German oncology centers. The study end point was time to tumor progression.

Results

Overall, 47.1% of patients (95% confidence interval (CI): 39.9–54.1%) remained in remission for more than 5 years, while the median time to progression was 4.5 years (95% CI: 4.0–6.6 years). Lower age (<50 years) and good performance status (ECOG 0) at time of trastuzumab treatment initiation as well as complete remission after initial trastuzumab treatment were associated with longer time to progression. Interruption of trastuzumab therapy correlated with shorter time to progression.

Conclusions

HER2-positive patients, who initially respond to palliative treatment with trastuzumab, can achieve a long-term tumor remission of several years.