Receptor tyrosine kinase-like orphan receptor 1: a novel target for cancer immunotherapy.

INTRODUCTION: Receptor tyrosine kinase-like orphan receptor 1 (ROR1) is a member of the receptor tyrosine kinase family. ROR1 is selectively overexpressed in a number of solid and hematological malignancies without significant expression in normal adult tissues. There are also some lines of evidence, which support the critical role of ROR1 in tumorigenesis. These characteristics introduce ROR1 as a suitable target for selective cancer immunotherapy. ROR1 targeting using different approaches such as siRNA, tyrosine kinase inhibitors and antibody induces tumor growth suppression in cancer cells. AREAS COVERED: The current review focuses on ROR1 structure and biological functions, expression profiles in normal and malignant tissues and its potential therapeutic applications in different malignancies. We aimed to encompass almost all important aspects of ROR1 biology and its importance in tumor targeted therapy approaches based on published papers in this field. EXPERT OPINION: Considering ROR1 unique characters, it seems that it can pass most of the criteria for being an ideal target for cancer immunotherapy. ROR1 unique expression on cancer cells with subtle expression on normal tissues make it a suitable target with minimum potential side effects using different cancer therapy approaches such as mAb therapy, peptide and protein vaccination, cell therapy and small molecules.