Effects of three different anti-ErbB2 antibodies on prostate tumors

Prostate cancer is the most commonly diagnosed malignancy in men in developed countries. ErbB2 contributes to prostate cancer progression by activating the androgen receptor in a steroid poor environment, thus promoting androgen-independent cell growth and survival. The consequent development of hormone refractory tumors is a major obstacle in prostate cancer therapy. The inhibition of ErbB2 signal transduction pathways by the use of human antibodies has been considered as a valuable alternative strategy for cancer therapy. Herein we report a comparative analysis of the antitumor effects of three different antibodies targeting different epitopes of ErbB2: Herceptin (Trastuzumab), 2C4 (Pertuzumab), and Erb-hcAb, a novel fully human compact antibody produced in our laboratory. We demonstrate that the in vitro and in vivo growth of both androgen- dependent and †"independent prostate cancer cells is efficiently inhibited by Erb-hcAb, which shows antitumor effects on some cell lines more potent than those observed for either Herceptin or 2C4