Effect On Tumor Growth By Tgf-Beta 1/Cox-2 Sirna Combination Product (Stp705) In A Human Cholangiocarcinoma (Hucct-1) Xenograft Tumor Model In Nude Mice.

e14652 Background: Cholangiocarcinoma (CCA) is a hepatobiliary cancer and although there have been advances recently there is a need for additional treatment methods for patients. Over expressions of TGF-β1 and COX-2 have been reported to play key roles in tumorigenesis of CCA. We studied the effect of STP705 on the growth of HuCCT-1 xenograft tumors in nude mice. STP705 is a TGF-β1/COX-2 specific siRNA combination product formulated in Histidine-Lysine co-Polymer nanoparticle delivery system. Methods: HuCCT-1 xenograft tumors were implanted subcutaneously into 24 BALB/c nude female mice (n = 8/group). Group 1 received vehicle control, group 2 (low-dose) received 8µg of STP705, and group 3 (high-dose) received 16µg of STP705. Intratumoral test article administration and tumor volume measurements were conducted twice a week for 3-weeks. Qualitative analysis was performed on H&E, Picrosirius red (PSR) and immunohistochemistry (IHC) stained sections of tumor tissues. Results: High- and low- dose groups of STP705 reported significantly lower mean tumor volume at day 21 (p = 0.005 & p = 0.036, respectively) as compared to control group. High-dose group reported significantly lower tumor volume at days 11 (p = 0.042), 15 (p = 0.003), and 18 (p = 0.007) as compared to the control group. IHC assessment demonstrated that STP705-treated animals had significantly lower (H-score ± SEM) TGF-β1, COX-2, HSP70, Bcl-xL and MMP-9 staining (52±9, 39±4, 178±8, 25±7 & 7±1, respectively) as compared to control animals (94±11, 66±8, 213±7, 59±8 & 11±2, respectively – with p < 0.05). Assessment of Caspase-3 and H&E (necrosis and inflammation) slides reported higher mean score for STP705-treated animals, while PSR staining reported lower fibroplasia for STP705-treated animals as compared to the control animals. Conclusions: The data suggests that STP705-treatment suppresses TGF-β1 and COX-2 expression resulting in inhibition of (i) tumor cell survival, (ii) fibrosis, (iii) promotes apoptosis, and (iv)decreased invasiveness of tumor cells. Overall, STP705 is an innovative siRNA-based treatment that results in significant suppression of tumor growth in a HuCCT-1 xenograft mouse tumor model.