HER2 阳性早期乳腺癌患者的 β2 肾上腺素能受体基因表达：NCCTG-N9831（Alliance）试验事后分析

Beta-2 adrenergic receptor ( 2AR) modulates immune activation and may enhance trastuzumab activity. We assessed the impact of 2AR gene (ADRB2) expression on the outcomes of patients with HER2-positive early-stage breast cancer enrolled on the NCCTG-N9831 trial.

This is a post-hoc analysis of the NCCTG-N9831 trial, which compared chemotherapy (arm A) versus chemotherapy plus trastuzumab (arms B&C) as adjuvant treatment of patients with HER2-positive early-stage breast cancer, with disease-free survival (DFS) as primary endpoint. Gene expression levels retrieved by DASL assay were used to classify patients as ADRB2-high or ADRB2-low. Hazard ratios (HRs) were calculated by a Cox proportional model adjusted for prognostic variables and ADRB2 expression. Correlations between ADRB2 expression and stromal tumor-infiltrating lymphocyte (TIL) levels were assessed with Pearson coefficient. A multivariable Cox regression model with interaction term was performed to assess the interaction between ADRB2 expression and treatment arm; and ADRB2 expression and a 8-gene signature previously shown to predict trastuzumab benefit.

Overall, 1,282 patients were included (ADRB2-high [N = 944] / ADRB2-low [N = 338]). A high expression of ADRB2 was associated with a longer DFS (P = .01) in the overall population. The addition of trastuzumab to chemotherapy improved DFS only in patients with ADRB2-high tumors (P < .01). ADRB2 expression was correlated with TIL levels (r = 0.24, P < .001). No association between ADRB2 expression and the 8-gene trastuzumab benefit signature was observed (P = .32).

Our findings suggest that a high ADRB2 expression is a favorable prognostic factor and may identify patients with HER2-positive early-stage breast cancer who benefit from adjuvant trastuzumab. TRIAL REGISTRATION: clinicaltrials.gov NCT00005970.