Evaluation of a Novel Anti-P-Selectin Aptamer ARC5690 On Venous Inflammation Following Acute Venous Thrombosis.

P-selectin is a pro-inflammatory molecule that increases neutrophil recruitment to the vein wall at the site of thrombosis. Aptamers are short single-stranded oligonucleotides with the ability to bind small molecules and diverse proteins such as P-selectin. P-selectin could be targeted by a specific inhibitor or novel aptamer to limit inflammation following deep vein thrombosis (DVT). In this study, the effect of a novel anti-P-selectin aptamer on reducing DVT associated inflammation was evaluated.

Male C57BL/6J mice (20-25g) were placed into groups: anti-P-selectin aptamer ARC5690 (APSA, 2mg/kg, 5mg/kg, and 10mg/kg intraperitoneal [IP]), anti-P-selectin control aptamer “scrambled sequence” (PSCA 1mg/kg and 10 mg/kg IP), anti-P-selectin antibody (APSB 0.2mg/kg IP), ligation only (LO), or true control (TC). Inferior vena cava (IVC) ligation, below the renal vein, was performed on all groups except TC. Groups PSCA and APSA received daily injections starting two days pre-IVC ligation and continued up to 3 days post-IVC ligation. Groups TC and LO did not receive test compounds. At 3 days post-IVC ligation, mice were euthanized. The IVC was harvested and weighed or submitted for vein wall morphometric inflammatory cell histological analysis. Blood was collected via cardiac puncture for plasma soluble P-selectin (sP-sel) protein analysis. Data was analyzed using a student t-test and Kruskal-Wallace test with a Dunn's multiple comparison test.

The total leukocyte counts in APSA groups 5 mg/kg and 10 mg/kg were significantly reduced compared to the PSCA groups and APSA group 2 mg/kg (p<0.05). The inflammatory cell count in APSA groups 5mg/kg and 10mg/kg confirmed this same trend for neutrophils, monocytes, lymphocytes versus the PSCA and APSA 2 mg/kg groups. Increased neutrophil counts were observed in the PSCA group compared to the TC group Figure 1). The thrombus weight (TW) was significantly decreased in the APSA 5mg/kg group compared to the LO group and the PSCA 1mg/kg group (p<0.05). The TW in the APSB group was significantly decreased compared to the LO group, the PSCA group (1mg/kg and 10mg/kg). There was a positive correlation between TW and sP-sel (Spearman correlation r=0.55).

ARC5690 showed a significant anti-inflammatory effect at the 5 mg/kg and 10 mg/kg doses. A reduction in TW was observed using an anti P-selectin aptamer with a positive correlation between TW and sP-sel levels, providing evidence that sP-sel could be a clinical biomarker of venous thrombosis. The reduction of venous inflammation by p-selectin blockade could have benefit in reducing the sequelae of DVT including venous fibrosis.

Kurz:Archemix: Research Funding. Schaub:Archemix: Research Funding.