Anti-HER2 Therapy After WBRT Increases Survival in Brain Mets Patients

Both chemotherapy and anti–human epidermal growth factor receptor 2 (HER2) therapy can improve survival outcomes in HER2-positive breast cancer patients with brain metastases who undergo whole-brain radiotherapy (WBRT), according to a new retrospective study.

“The incidence of brain metastases is higher in HER2-positive breast cancer compared with other breast cancer patients,” wrote study authors led by Jiayi Chen, MD, of Shanghai Cancer Center at Fudan University in China. “Although adjuvant trastuzumab could not effectively prevent brain metastases, recent studies demonstrated a significant survival benefit of salvage trastuzumab-based therapy for these patients.”

In the study, the authors retrospectively analyzed 60 patients with HER2-positive breast cancer and brain metastases who underwent WBRT to examine the benefits of various systemic therapies in this setting. The results were published in Breast Cancer.

The cohort was divided into three groups based on anti-HER2 therapy: group A received anti-HER2 therapy without adjuvant trastuzumab-based therapy (17 patients); group B received anti-HER2 therapy with adjuvant trastuzumab-based therapy (7 patients); and group C never received anti-HER2 therapy (36 patients).

The median overall survival (OS) after undergoing WBRT was 12 months for the full cohort. The OS rate was 56% at 1 year, 31% at 2 years, and 17% at 3 years.

The median OS was longer for those who received anti-HER2 therapy. Those in group A had a median OS of 27 months, compared with 16 months in group B and 9 months in group C (P = .002). Most of the patients (54%) who received both anti-HER2 therapy and chemotherapy were alive at 3 years, compared with 36% of group B and 19% of group C.

On multivariate analysis, receiving anti-HER2 therapy after WBRT was significantly associated with improved survival, with a hazard ratio (HR) of 4.02 (95% confidence interval [CI], 1.86–8.69; P < .001). Chemotherapy was also significantly associated with better survival, with an HR of 2.30 (95% CI, 1.16–4.56; P < .001).

The authors noted that their study is limited by its small size and the related inability to conduct subgroup analyses.

“Our study indicates that both chemotherapy and anti-HER2 therapy after WBRT were important predictors of improved OS,” they concluded. “Moreover, patients without prior exposure to adjuvant anti-HER2 treatment may have survival benefit superior to those of patients with prior exposure. Prior trastuzumab exposure may be considered in treatment planning and during enrollment in clinical trials of HER2-targeted therapy for brain metastases.”