EpCAM expression in retinoblastoma: a novel molecular target for therapy.

Purpose: This study was conducted to investigate the potential of targeting epithelial cell adhesion molecules (EpCAMs) in the treatment of retinoblastoma. It was first determined whether EpCAM is expressed in retinoblastoma and then whether EpCAM reactivity correlates with tumor aggressiveness.

Methods: EpCAM reactivity was evaluated by immunohistochemistry in 43 retinoblastoma specimens from 43 patients, by using the monoclonal antibody GA733.2. The tumors were divided into two groups. There were 20 tumors with no invasion of the choroid and optic nerve (group A) and 23 tumors with invasion of the choroid, optic nerve, and orbit (group B). EpCAM reactivity was correlated with invasion and differentiation of the tumors.

Results: Among the 43 tumors, EpCAM reactivity was observed in 100% (43/43) tumors. EpCAM reactivity was significantly higher in the invasive than the noninvasive tumors (P < 0.05) and in poorly differentiated than in well-differentiated tumors (P < 0.005). Non-neoplastic retina also expressed EpCAM.

Conclusions: The results confirm that EpCAM is vastly expressed in retinoblastoma and point to its use as a target for therapy in the future.