Cell experiment:

T24, UM-UC-14, UROtsa, and HeLa cells are plated in 96-well dishes in triplicate at 1×103 cells per well and allowed to adhere for 24 hours. Subsequently, Tiplaxtinin is added to the wells and allowed to incubate at the indicated concentrations. Cellular proliferation is determined by CellTiter-Glo Luminescent Cell Viability Assay at 24 hours, and IC50 of Tiplaxtinin is determined in Graphpad Prism. Luminescence is measured using a FLUOstar OPTIMA Reader[2].

Animal experiment:

Rats[1] Male Sprague-Dawley rats (250-350 g) are dosed orally with either vehicle or Tiplaxtinin (0.3-3 mg/kg) on the morning of the experiment, then anesthetized with sodium-pentobarbital (50 mg/kg, i.p.). A midline incision is made along the neck, and the right and left carotid arteries and jugular veins are exposed. The left jugular vein is catheterized for tPA delivery and blood sampling. The right carotid artery is cannulated with PE-60 tubing filled with 3.8% sodium citrate solution, and interfaced to a saline-filled pressure transducer for monitoring of heart rate and blood pressure. The left carotid artery is used for vascular injury induction and thrombosis. An ultrasonic flow probe is placed on the left carotid artery, and baseline blood flow is recorded. A 3-mm section of PE-60 tubing is sectioned longitudinally, and a piece of filter paper saturated with 25% FeCl3 is inserted into the tubing. Flow is monitored in the damaged vessel during tPA infusion and for an additional 20 min afterwards. At the end of the experiment, the arterial thrombus is excised and weighed. Mice[2] Mice bearing bladder xenografts and mice bearing cervical xenografts are divided randomly into three groups (control, 5 mg/kg of Tiplaxtinin, and 20 mg/kg of Tiplaxtinin) and treatment is initiated. Each group is composed of at least 10 mice. No toxicity or weight loss is noted in any of the treatment groups. Tiplaxtinin (100 μL diluted in corn oil) is administered via oral gavage daily (Monday-Friday) for 5 weeks. Control mice received vehicle alone on the same schedule. Tumor volumes are measured weekly with digital calipers and calculated. After 5 weeks, the mice are sacrificed, tumors resected, and analyzed by immunohistochemical staining.

Description:

IC50: 2.7 μM

Plasminogen activator inhibitor-1 (PAI-1) is the most important physiologic regulator of the plasminogen activation system through its inhibition of its target serine proteases, tissue plasminogen activator, and urokinase plasminogen activator. Significant elevations of PAI-1 lead to stabilization of arterial and venous thrombi, which contribute respectively to coronary arterial occlusion in postmyocardial infarction and venous thrombosis following postoperative recovery from orthopedic surgery. Tiplaxtinin (PAI-039) is a novel, orally efficacious inhibitor of PAI-1.

In vitro: Tiplaxtinin inhibited PAI-1 as determined by the antibody method. By use of fluorescent spectroscopy, tiplaxtinin bound to the PAI-1 mutant selectively with a Kd of 480 nM. This binding event was saturable and associated with inhibition of the protein [1].

In vivo: In the rat model of carotid thrombosis, oral administration of tiplaxtinin at 1 mg/kg increased time to occlusion and prevented the carotid blood flow reduction when compared to the vehicle group. All of the vehicle control rats exhibited thrombosis with an average time to occlusion of 11 min and a complete reduction of 100% carotid flow. Conversely, those rats receiving tiplaxtinin at 1 mg/kg po exhibited an average time to occlusion of >50 min and a carotid blood flow reduction of approximately 50% [1].

Clinical trial: Up to now, tiplaxtinin is still in the preclinical development stage.

Reference:
[1] Elokdah H, Abou-Gharbia M, Hennan JK, McFarlane G, Mugford CP, Krishnamurthy G, Crandall DL.  Tiplaxtinin, a novel, orally efficacious inhibitor of plasminogen activator inhibitor-1: design, synthesis, and preclinical characterization. J Med Chem. 2004 Jul 1;47(14):3491-4.