Yezhou Sheng

Combretastatin family member OXI4503 induces tumor vascular collapse through the induction of endothelial apoptosis

The mechanism of tumor cell killing by OXI4503 was investigated by studying vascular functional and morphological changes post drug administration. SCID mice bearing MHEC5‐T hemangioendothelioma were given a single dose of OXI4503 at 100 mg/kg. Tumor blood flow, measured by microsphere fluorescence, was reduced by 50% at 1 hr, and reached a maximum level 6–24 hr post drug treatment. Tumor vascular permeability, measured by Evans blue and hemoglobin, increased significantly from 3 hr and peaked at 18 hr. The elevated tumor vessel permeability was accompanied by an increase in vascular endothelial growth factor (VEGF) from 1 hr post drug treatment. Immunohistochemical staining for CD31 and laminin showed that tumor blood vessels were affected as early as 3 hr but more prominent from 6 hr. From 12 hr, the vessel structure was completely destroyed. Histopathological and double immunohistochemical staining showed morphological change and induction of apoptosis in endothelial cells at 1–3 hr, followed by tumor cell necrosis from 6–72 hr. There were no statistically significant changes of Evans blue and hemoglobin contents in liver tissue over the time course. These results suggest that OXI4503 selectively targets tumor blood vessels, and induces blood flow shutdown while it enhances tumor blood vessel permeability. The early induction of endothelial cell apoptosis leads to functional changes of tumor blood vessels and finally to the collapse of tumor vasculature, resulting in massive tumor cell necrosis. The time course of the tumor vascular response observed with OXI4503 treatment supports this drug for development as a stand alone therapy, and also lends support for the use of the drug in combination with other cancer therapies.

Treatment of chemotherapy-induced leukopenia in a rat model with aqueous extract from Uncaria tomentosa.

The Uncaria tomentosa water extracts (C-Med-100) depleted of indole alkaloids (< 0.05%, w/w) have been shown to induce apoptosis and inhibit proliferation in tumor cells in vitro and to enhance DNA repair, mitogenic response and white blood cells in vivo. In this study, the effect of C-Med-100 in the treatment of chemically induced leukopenia was evaluated in a rat model. W/Fu rats were treated first with doxorubicin (DXR) 2 mg/kg x 3 (i.p. injection at 24 hour-intervals) to induce leukopenia. Twenty-four hours after the last DXR treatment, the rats were daily gavaged with C-Med-100 for 16 consecutive days. As a positive control, Neupogen, a granulocyte colony stimulator was also administered by subcutaneous injection at a dose of 5 and 10 microg/ml for 10 consecutive days. The results showed that both C-Med-100 and Neupogen treatment groups recovered significantly sooner (p < 0.05 by Duncan test) than DXR group. However, the recovery by C-Med-100 treatment was a more natural process than Neupogen because all fractions of white blood cells were proportionally increased while Neupogen mainly elevated the neutrophil cells. These results were also confirmed by microscopic examination of the blood smears. The mechanism of the C-Med-100 effect on WBC is not known but other data showing enhanced effects on DNA repair and immune cell proliferative response support a general immune enhancement.

DNA repair enhancement of aqueous extracts of Uncaria tomentosa in a human volunteer study

The Uncaria tomentosa water extracts (C-Med-100) have been shown to enhance DNA repair, mitogenic response and leukocyte recovery after chemotherapy-induced DNA damage in vivo. In this study, the effect of C-Med-100 supplement was evaluated in a human volunteer study. Twelve apparently healthy adults working in the same environment were randomly assigned into 3 groups with age and gender matched. One group was daily supplemented with a 250 mg tablet containing an aqueous extract of Uncaria tomentosa of C-Med-100, and another group with a 350 mg tablet, for 8 consecutive weeks. DNA repair after induction of DNA damage by a standard dose of hydrogen peroxide was measured 3 times before supplement and 3 times after the supplement for the last 3 weeks of the 8 week-supplement period. There were no drug-related toxic responses to C-Med-100 supplement when judged in terms of clinical symptoms, serum clinical chemistry, whole blood analysis and leukocyte differential counts. There was a statistically significant decrease of DNA damage and a concomitant increase of DNA repair in the supplement groups (250 and 350 mg/day) when compared with non-supplemented controls (p < 0.05). There was also an increased tendency of PHA induced lymphocyte proliferation in the treatment groups. Taken together, this trial has confirmed the earlier results obtained in the rat model when estimating DNA repair enhancement by C-Med-100.

Persistent response to pneumococcal vaccine in individuals supplemented with a novel water soluble extract of Uncaria tomentosa, C-Med-100.

A human intervention study was carried out using male volunteers attending a General Practice Clinic in New York City involving comparison of individuals supplemented with 350 mg x 2 C-Med-100 daily dose for two months with untreated controls for their abilities to respond to a 23 valent pneumococcal vaccine. C-Med-100 is a novel nutraceutical extract from the South American plant Uncaria tomentosa or Cats Claw which is known to possess immune enhancing and antiinflammatory properties in animals. There were no toxic side effects observed as judged by medical examination, clinical chemistry and blood cell analysis. However, statistically significant immune enhancement for the individuals on C-Med-100 supplement was observed by (i) an elevation in the lymphocyte/neutrophil ratios of peripheral blood and (ii) a reduced decay in the 12 serotype antibody titer responses to pneumococcal vaccination at 5 months.

Synthesis, in vitro, and in vivo evaluation of phosphate ester derivatives of combretastatin A-4

Combretastatin A-4 disodiumphosphate (CA4P), a prodrug formulation of the natural product combretastatin A-4 (CA4), is currently in clinical investigation for the treatment of cancer. In vivo, CA4P is rapidly enzymatically converted to CA4, a potent inhibitor of tubulin polymerization (IC(50)=1-2 microM), and rapidly causes bloodflow shutdown in tumor tissues. A variety of alkyl and aryl di- and triesters of CA4P have been synthesized and evaluated as potential CA4 prodrugs and/or stable CA4P analogues.

Acidic and neutralized metoclopramide formulations sensitize ionizing radiation induced cytotoxicity in a human lung adenocarcinoma xenografted to scid mice.

A neutralized formulation (Neu-Sensamide) of metoclopramide (MCA) has been shown to possess reduced sedative side effects compared with the conventional acidic formulations (Primperan). The acidic formulation of MCA has also been shown to sensitize the effect of ionizing radiation (6-8 Gy) using human squamous cell carcinomas from the head and neck xenografted to nude mice. In the present study, 2 mg MCA/kg body weight 1-3 h before treatment with 1 Gy radiation (single dose) was evaluated in scid mice xenografted with a human lung adenocarcinoma. MCA given alone in acidic or neutralized formulations did not show any effect on tumor growth retardation. However, when combined with radiation, both acidic and neutralized formulations of MCA sensitized the cytotoxic effect of radiation directed against the tumors by increasing tumor doubling time, tumor quadrupling time and specific growth delay, and by decreasing area under growth curve measurements. In addition, there was no statistically significant difference between the two formulations of MCA in the efficacy of sensitizing the cytotoxicity of a single low dose (1 Gy) of radiation.