The Potential Usefulness of 99mTc-HYNIC-(Ser)3-LTVPWY Peptide for Predicting HER2 Status Alteration After Chemotherapy in Ovarian Tumor-Bearing Mice.

Abstract

Purpose: The assessment of HER2 expression has a significant impact on optimizing cancer treatment protocol in patients. The aim of this study was to evaluate the potential usefulness of ^99mTc-HYNIC-(Ser)₃-LTVPWY peptide for detecting HER2 alteration after paclitaxel therapy of ovarian tumor xenografts in nude mice. Materials and Methods: Mice bearing SKOV-3 tumors were treated with paclitaxel and saline. The antitumor efficacy of paclitaxel was compared with the control group in tumor size and histopathological examinations. In biodistribution and imaging studies, the tumor uptakes of radiolabeled peptide were evaluated in mice-bearing ovarian tumors in both groups. The HER2 expressions in transplanted tumors were analyzed by immunohistochemistry (IHC). Results: Tumor size gradually increased in all mice during the treatment, whereas tumors had considerably faster growth in the saline group compared to those in the paclitaxel-treated mice. Paclitaxel could suppress ovarian tumor growth and prevent vascular and cell proliferation in the tumoral mass. Biodistribution and imaging results demonstrated nonsignificant radionuclide accumulations in transplanted tumors in the paclitaxel- and saline-treated groups. IHC staining confirmed the HER2 status that was similar in both groups. Conclusions: The response of HER2 status to paclitaxel in mice bearing HER2-expression tumors was profitably monitored by HER2 targeted ^99mTc-HYNIC-(Ser)₃-LTVPWY peptide that was agreement with IHC. The utilization of this radiolabeled peptide may be a valuable probe in evaluating HER2 status after chemotherapy.