Identification of New Prognostic Markers and Therapeutic Targets for Non-Muscle Invasive Bladder Cancer: HER2 as a Potential Target Antigen

HER2 overexpression predicts pathological T2 stage and improved survival in de novo muscle-invasive bladder cancer after immediate radical cystectomy: a retrospective cohort study

INTRODUCTION

Human epidermal growth factor receptor type 2 (HER2) overexpression is a prognostic factor and a therapeutic target for breast cancer; however, anti-HER2 therapies are ineffective in patients with bladder cancer. The authors investigated the effect of HER2 overexpression (HER2 + ) on the prognosis of muscle-invasive bladder cancer (MIBC).

MATERIALS AND METHODS

This retrospective cohort study included patients who underwent initial transurethral resection of bladder tumors between 2005 and 2013 and were registered in the Korea National Health Insurance Database, which provides data on overall survival (OS). Sixty-one patients with clinically nonmetastatic de novo MIBC were included in this study. As a subgroup, 33 patients who underwent immediate radical cystectomy (RC) were analyzed. Univariate and multivariate Cox proportional hazards models were used to identify prognostic factors for survival. A multivariable binary logistic regression model was used to identify the favorable T stage.

RESULTS

Among the 61 patients with d-MIBC, 14 were HER2 + and 47 HER2 - . Age less than 70 years [hazard ratio (HR): 0.312, CI: 0.16-0.59, P <0.001] and HER2 + status (HR: 0.40, CI: 0.19-0.85, P =0.02) were favorable prognostic factors for OS after adjusting for clinical variables. In the RC subgroup, HER2 + status was a significant predictive factor for the pT2 stage (HR): 36.8, CI: 4.83-797.41, P <0.01). Age less than 70 years (HR: 0.15, CI: 0.05-0.42, P <0.001) and HER2 + status (HR: 0.11, CI: 0.02-0.54, P =0.01) were favorable prognostic factors for OS after adjusting for RC pathological variables.

CONCLUSIONS

HER2 + status could be a marker for an indolent subset of MIBC and could predict favorable survival regardless of RC status. Moreover, HER2 + status not only consistently predicted a favorable T stage after RC, but also predicted better survival than pathological outcomes.

Molecular Targeting of the Human Epidermal Growth Factor Receptor-2 (HER2) Genes across Various Cancers

Human epidermal growth factor receptor 2 (HER2) belongs to the ErbB family, a group of four transmembrane glycoproteins with tyrosine kinase activity, all structurally related to epidermal growth factor receptor (EGFR). These tyrosine kinases are involved in the transmission of cellular signals controlling normal cell growth and differentiation. If this transmission goes awry, it can lead to dysregulated growth of the cell. HER2 specifically can be implicated in the pathogenesis of at least eight malignancies. HER2 positivity quickly became a well-characterized indicator of aggressiveness and poor prognosis, with high rates of disease progression and mortality. After realizing the implication of HER2, it first became investigated as a target for treatment in breast cancer, and later expanded to areas of research in other cancer types. To this day, the most therapeutic advancements of anti-HER2 therapy have been in breast cancer; however, there have been strong advancements made in the incorporation of anti-HER2 therapy in other cancer types as well. This comprehensive review dissects HER2 to its core, incorporating the most up to date information. The topics touched upon are discussed in detail and up to 200 published sources from the most highly recognized journals have been integrated. The importance of knowing about HER2 is exemplified by the groundbreaking advancements that have been made, and the change in treatment plans it has brought to the oncological world in the last twenty years. Since its groundbreaking discovery there have been significant breakthroughs in knowledge regarding the actual receptor, the receptors biology, its mechanism of action, and advancements in tests to detect HER2 and significant strides on how to best incorporate targeted treatment. Due to the success of this field thus far, the review concludes by discussing the future of novel anti-HER2 therapy currently in development that everyone should be aware of.