Abstract 580: hENT1 testing in pancreatic ductal adenocarcinoma: Are we ready yet? A comparative analysis of the murine and the rabbit antibodies

Abstract

Abstract Introduction Human equilibrative nucleoside transporter 1 (hENT1) level of expression in pancreatic adenocarcinoma (PAC) may predict survival in gemcitabine-treated patients after resection. These results have been obtained with a murine anti-hENT1 antibody (10D7G2), which is not commercially available. Another antibody, rabbit-derived (SP120), appears to have no predictive value in local, advanced or metastatic PAC. This raises the question of the equivalence of the antibodies. Patients and Methods Murine (10D7G2) and rabbit (SP120) monoclonal anti-hENT1 antibodies were applied on the same tissue microarrays of resected PAC. Two sets of patients from 2 separate institutions (n = 147 each) were used to compared hENT1 expression with both antibodies on two different immunochemistry automates. An additional amplification technique was performed on the second set. hENT1 expression was scored as previously reported. Results were correlated with overall survival (OS) following gemcitabine treatment. Results The rate of “hENT1 high” cases was lower with the SP120 clone (set 1: 7 versus 48%, set 2:11 versus 38%). With the amplification technique, the rate of “hENT1 high” cases was globally similar between both antibodies. However, the concordance between the antibodies was found in only 50% of cases. High hENT1 expression was predictive of OS with the 10D7G2 antibody (HR = 0.49; 95% CI: 0.24-0.98; P = 0.045) but not with the SP120 (HR = 1.61; 95% CI: 0.80-3.21; P = 0.18). Conclusion Our data suggest that the two antibodies are not equivalent. Further studies are ongoing and will be presented at the meeting: 1/ Comparative analysis of the rabbit antibody on a larger series (n = 471) with staining performed by Ventana® (Roche®), 2/ Comparative analysis of 3 additional anti-hENT1 antibody together with mRNA level correlation, 3/ Comparative expression of hENT1 in a series of matched primary tumors-metastases. Citation Format: Jerome Cros, Raphael Marechal, Jean Baptiste Bachet, Pierre Laurent-Puig, Jean Francois Flejou, Pieter Demetter, Magali Svrcek. hENT1 testing in pancreatic ductal adenocarcinoma: Are we ready yet? A comparative analysis of the murine and the rabbit antibodies. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 580. doi:10.1158/1538-7445.AM2015-580