Immunohistochemical prediction of lapatinib efficacy in advanced HER2-positive breast cancer patients

Molecular mechanisms of lapatinib resistance in breast cancer are not well understood. The aim of this study was to correlate expression of selected proteins involved in ErbB family signaling pathways with clinical efficacy of lapatinib. Study group included 270 HER2-positive advanced breast cancer patients treated with lapatinib and capecitabine. Immunohistochemical expression of phosphorylated adenosine monophosphate-activated protein (p-AMPK), mitogen-activated protein kinase (p-MAPK), phospho (p)-p70S6K, cyclin E, phosphatase and tensin homolog were analyzed in primary breast cancer samples. The best discriminative value for progression-free survival (PFS) was established for each biomarker and subjected to multivariate analysis. At least one biomarker was determined in 199 patients. Expression of p-p70S6K was independently associated with longer (HR 0.45; 95% CI: 0.25–0.81; p = 0.009), and cyclin E with shorter PFS (HR 1.83; 95% CI: 1.06–3.14; p = 0.029). Expression of p-MAPK (HR 1.61; 95% CI 1.13–2.29; p = 0.009) and cyclin E (HR 2.99; 95% CI: 1.29–6.94; p = 0.011) was correlated with shorter, and expression of estrogen receptor (HR 0.65; 95% CI 0.43–0.98; p = 0.041) with longer overall survival. Expression of p-AMPK negatively impacted response to treatment (HR 3.31; 95% CI 1.48–7.44; p = 0.004) and disease control (HR 3.07; 95% CI 1.25–7.58; p = 0.015). In conclusion: the efficacy of lapatinib seems to be associated with the activity of downstream signaling pathways – AMPK/mTOR and Ras/Raf/MAPK. Further research is warranted to assess the clinical utility of these data and to determine a potential role of combining lapatinib with MAPK pathway inhibitors.

Expression of phosphorylated Akt, mTOR and MAPK in type I endometrial carcinoma: clinical significance

BACKGROUND/AIM

The Akt/mTOR and MAPK pathways are frequently activated in various tumor types but data on endometrial carcinoma are limited. The aim of the present study was to investigate the clinical significance of the expression of phosphorylated MAPK, Akt and mTOR (p-MAPK, p-Akt, p-mTOR) in type I endometrial carcinoma.

MATERIALS AND METHODS

The study comprised of 103 formalin-fixed paraffin-embedded (FFPE) type I endometrial carcino ma cases, retrospectively retrieved and assessed by immuno histochemistry for p-MAPK, p-Akt and p-mTOR expression. The expression of these proteins was also studied in non-neoplastic endometrial tissue adjacent to the tumor.

RESULTS

The expression patterns of these molecules differed between malignant and non-tumorous tissue specimens. The immuno reactivity for p-Akt was exclusively detected in the neoplastic tissues. Expression levels of p-MAPK were higher in tumors compared to non-neoplastic endometrium (p<0.001), while p-mTOR was found to be over-expressed in non-neo plastic endometrium compared to carcinomas (p=0.001). Expression of p-Akt was correlated with p-MAPK protein levels (p=0.022, r=0.229). On the other hand, no association was found with clinicopathological parameters and with disease-free (DFS) or overall survival (OS) of the patients.

CONCLUSION

Our findings support the de-regulation of the PI3K/Akt/mTOR and MAPK signaling pathways in type I endometrial carcinomas suggesting involvement of these pivotal pathways in endometrial carcinogenesis.