Safety studies on intravenous infusion of a potent angiogenesis inhibitor: taurocholate-conjugated low molecular weight heparin derivative LHT7 in preclinical models.

CONTEXT: As a class of angiogenesis inhibitors, heparin conjugates have shown significant effectiveness in several studies. OBJECTIVES: The purpose of our current study is to evaluate the effectiveness and safety of infusing the conjugate of low molecular weight heparin and taurocholate (LHT7), which has been developed as a potent angiogenesis inhibitor. METHODS: To evaluate its safety, the method of intravenous infusion was compared with its i.v. bolus administration. Intravenous infusion was administered at a rate of 400 µl/min/kg of body weight for 30 min. Pharmacokinetic (PK) analysis, organ accumulation, and plasma concentration profiles of LHT7 were measured. The anticancer effect of LHT7 was evaluated in murine and human xenograft models, and preclinical studies were performed in SD rats and beagle dogs. RESULTS: The results of the PK studies showed reduced organ accumulation in mice and the AUC(0-96 h) (area under the curve) was increased up to 1485 ± 125 h × µg/ml. The efficacy, at dose 1 mg/kg/2 d was higher for i.v. infusion than for i.v. bolus administration in both murine and human cancer models. The preclinical studies showed the safety dose of LHT7 is less than 20 mg/kg in SD rats and in the next safety analysis in beagle dogs showed that there were no organ-specific adverse effects in higher doses, such as, 12 mg/kg. LHT7 showed sustained effects with minimized adverse events when administered through i.v. infusion. CONCLUSIONS: LHT7 (i.v. infusion) could be safely used for further clinical development as a multi-targeting anti-angiogenic agent.

Prevention effect of orally active heparin conjugate on cancer-associated thrombosis.

Thrombogenesis is a major cause of morbidity and mortality in cancer patients. Prophylaxis with low-molecular-weight heparin (LMWH) is recommended for cancer patients, but requires non-parenteral delivery methods for long-term treatments. In this study, we sought to generate a new oligomeric-bile acid conjugate of LMWH that can be used for oral delivery. We first synthesized a tetramer of deoxycholic acid (tetraDOCA), which was site-specifically conjugated at the end saccharide of LMWH. When LMWH-tetraDOCA conjugate (LHe-tetraD) was orally administered at a dose of 5 mg/kg in ICR mice, the maximum anti-factor Xa level was increased up to 0.62±0.05 IU/mL without any evidence of liver toxicity, gastrointestinal damage, or thrombocytopenia. The cancer-associated thrombosis was induced in tumor-bearing mice by local heat application, and the fibrin deposition in tumors was evaluated. The oral administration of LHe-tetraD (either a single dose or multiple daily doses for up to 10 days) in mice substantially abolished the coagulation-dependent tropism of fibrinogen in the heated tumors and significantly decreased hemorrhage, compared to the mice treated with saline or subcutaneous injection of LMWH. Thus, the anticoagulation effect of oral LHe-tetraD invokes the benefits of oral delivery and promises to provide an effective and convenient treatment for cancer patients at risk of thrombosis.

Orally active desulfated low molecular weight heparin and deoxycholic acid conjugate, 6ODS-LHbD, suppresses neovascularization and bone destruction in arthritis.

The regulation of angiogenesis is an interesting area to consider for novel therapeutic approaches to rheumatoid arthritis (RA). Chemically modified heparins have been developed as possible candidates for angiogenesis inhibitor; however, they have a major clinical drawback in exhibiting poor oral bioavailability. Here, orally absorbable O-desulfated low molecular weight heparin (ODS-LMWH) derivatives were newly synthesized by conjugating 2-O- or 6-O-desulfated LMWH with deoxycholic acid (DOCA) or bisDOCA (a dimer of DOCA), and their physicochemical properties, antiangiogenic potency and pharmacokinetic profiles were assessed. After selecting the best candidate among those derivatives, its therapeutic efficacy on arthritis was investigated in a murine collagen antibody-induced arthritis (CAIA) model. ODS-LMWH derivatives significantly inhibited the capillary-like tube formation of human umbilical vein endothelial cells (HUVECs) and basic fibroblast growth factor (bFGF)-induced angiogenesis in the Matrigel plug assay. Among all the compounds, 6ODS-LHbD showed the highest oral bioavailability in rats (19.3%). In the CAIA mouse model, 6ODS-LHbD (10 mg/kg, p.o., S.I.D.) significantly inhibited neovascularization in the joint, the increase of hind-paw thickness, and the structural damage in the bone. Therefore, 6ODS-LHbD would be a promising candidate for an orally active drug for the treatment of RA.