Abstract 2855: Association between plasma tissue factor and tumor volume: A novel sensitive method for detecting plasma tissue factor

Proceedings: AACR Annual Meeting 2014; April 5-9, 2014; San Diego, CA Currently, much accumulated clinical evidence indicates that abnormal blood coagulation occurs in patients with various cancers. Tissue factor (TF) is an initiation factor of the extrinsic coagulation pathway, and plays a major role in blood coagulation. Increased blood levels of TF may be associated with a higher incidence of thrombotic complications. TF occurs in three functional forms: full-length TF (flTF), which is located in the cellular membrane as a transmembrane glycoprotein, micro-particles TF (MPsTF), which is released as microvesicles from cells, and alternatively spliced TF (asTF), which lacks a transmembrane domain and is released into the extracellular space. TF overexpression has been detected in several solid tumor cells. Especially in one study, TF was detected in 340 of 408 (83%) of pancreatic cancer tissue specimens. High TF expression has been reported to be associated with a poor prognosis in cancer patients. In the present study, we developed a new immunoassay system for human TF. We prepared a model of pancreatic cancer by subcutaneous implantation of the high TF-expressing human pancreatic cancer cell line BxPC-3 (n=10). Rat anti-human TF monoclonal antibody (anti-hTF mAb) clones 1006 and 1849 were prepared in our laboratory and used for our new sandwich ELISA system; anti-hTF mAb clone 1849 conjugated to magnetic beads for capturing, and anti-hTF mAb clone 1006 used for detecting antibody. In mice bearing subcutaneous tumors, the plasma and urinary TF concentrations before and after tumor resection were evaluated. The associations between tumor growth and the plasma and urinary TF concentrations were also evaluated. The ELISA system appeared to detect both the BxPC-3 cell lysate and the released TF present in the BxPC-3-conditioned medium. The anti-hTF mAb clone 1849 did not cross-react with mouse TF. Therefore, the novel sensitive human TF detection system specifically detected tumor-derived TF. Plasma TF increased with increase of the tumor volume. To evaluate the association between the tumor volume and plasma TF, we collected blood and urine every 10 days after the tumor inoculation. Plasma TF values, shown as means±SD, were 52±163 pg/mL at 10 days, 161±444 pg/mL at 20 days, and 380±843 pg/mL at 30 days after the inoculation. In the case of BxPC-3 tumor resection, the plasma TF was 2.0±3.0 pg/mL at 10 days after the resection. There was a positive correlation between the tumor volume of BxPC-3 and the plasma TF (Spearman's rank correlation coefficient, rs=0.555, P=0.0005). The TF forms detected in the mice bearing BxPC-3 xenografts were MPsTF and asTF, as determined by western blotting. On the other hand, urinary TF values were lower than the detection limit in this study. Plasma TF was positively associated with the subcutaneous tumor volume of BxPC-3. Thus, plasma TF may be useful as a tumor marker. We propose to apply our novel sensitive human TF detection system to human plasma samples. Citation Format: Yuki Fujiwara, Yohei Hisada, Ryuta Sato, Ryou Tsumura, Yoshikatsu Koga, Masahiro Yasunaga, Yasuhiro Matsumura. Association between plasma tissue factor and tumor volume: A novel sensitive method for detecting plasma tissue factor. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2855. doi:10.1158/1538-7445.AM2014-2855