Genetic heterogeneity of HER2 in breast cancer: impact on HER2 testing and its clinicopathologic significance.

In 2009, ASCO/CAP expanded its human epidermal growth factor receptor type 2 (HER2) testing guideline to define HER2 genetic heterogeneity (GH). However, the clinical significance of GH is unclear. We investigated the impact of HER2 GH on HER2 testing and studied its clinicopathologic significance. Paraffin-embedded tumor tissues of surgical resections of 617 non-consecutive breast carcinoma patients were studied by routine HER2 fluorescence in situ hybridization (FISH). HER2 GH was evaluated, and the results were correlated with HER2 protein expression by immunohistochemistry and HER2 gene amplification by FISH, and with various clinicopathologic parameters. HER2 GH was observed in 15.2 % (94/617) of the patients. It was associated with low-to-middle level of HER2 expression, and with none-to-low level of HER2 gene amplification. Among the 17 patients with equivocal HER2 FISH results, 35.3 % (6/17) of tumors displayed GH. In contrast with HER2-positive tumors without GH, tumors with HER2 GH demonstrated significant association with lower histologic grade, smaller tumor size, and proclivity to hormone receptor expression. HER2 GH is a substantial cause of equivocal HER2 testing results of breast cancer by FISH. Tumors with HER2 GH showed that biologic features resemble more of HER2-negative tumors than HER2-positive tumors without GH. The findings indicate a need of the guidelines to clarify whether tumors with HER2 GH truly benefit from HER2-targeted therapy of breast cancer.

Tumor secretion of CCL22 activates intratumoral Treg infiltration and is independent prognostic predictor of breast cancer.

It has been reported that dense intratumoral infiltration of Foxp3 (+)Tregs (Tregs) was an independent factor for poor prognosis of breast cancer (BC) patients. However, the cytokines activating the Treg infiltration are not known. This study was undertaken to evaluate the role of CCL22 and TGF-ß1 in this cascade and their prognostic significance for BC patients. 417 cases of invasive breast cancer were selected from the prior study cohort and the expressions of CCL22 and TGF-ß1 were assessed by immunohistochemistry. It was identified that tumor secretion of CCL22 was positively correlated with the intratumoral Treg infiltration (P<0.0001), but its association with lymphoid aggregates surrounding the tumor was not proven to be significant (P=0.056). Moreover, CCL22 expression was found to be associated with the tumor histological features known to be related with unfavorable prognosis of patients, including high histological grade (P<0.0001), negative ER (P<0.0001), negative PR (P=0.001), and HER2 amplification (P=0.028). Similar to intratumoral Treg infiltrates, CCL22 tumor secretion correlated with the prognosis of the molecular subtypes of breast carcinoma (P<0.0001). Univariate analysis revealed CCL22 to be an independent prognostic factor for overall survival (OS, P<0.0001) and progression-free survival (PFS, P<0.0001) of BC patients that were confirmed by multivariate analysis (P=0.011 and P=0.010 respectively). In contrast, although TGF-ß1 expression was positively correlated with both Tregs infiltrates into the tumor bed and lymphoid aggregates surrounding the tumor (P=0.023; P=0.046, respectively), its expression was not significantly associated with the molecular subtypes of breast carcinoma and the prognosis of the patients. Our study indicates that both CCL22 and TGF-ß1 are candidate chemoattractants for intratumoral Foxp3 (+)Tregs infiltration; however, unlike the later, CCL22 is an independent prognostic predictor of BC patients, and it therefore may have the potential to serve as a target for immunotherapeutic strategy of BC.