Safety and Feasibility of Long-term Intravenous Sodium Nitrite Infusion in Healthy Volunteers

BACKGROUND: Infusion of sodium nitrite could provide sustained therapeutic concentrations of nitric oxide (NO) for the treatment of a variety of vascular disorders. The study was developed to determine the safety and feasibility of prolonged sodium nitrite infusion. METHODOLOGY: Healthy volunteers, aged 21 to 60 years old, were candidates for the study performed at the National Institutes of Health (NIH; protocol 05-N-0075) between July 2007 and August 2008. All subjects provided written consent to participate. Twelve subjects (5 males, 7 females; mean age, 38.8±9.2 years (range, 21-56 years)) were intravenously infused with increasing doses of sodium nitrite for 48 hours (starting dose at 4.2 µg/kg/hr; maximal dose of 533.8 µg/kg/hr). Clinical, physiologic and laboratory data before, during and after infusion were analyzed. FINDINGS: The maximal tolerated dose for intravenous infusion of sodium nitrite was 267 µg/kg/hr. Dose limiting toxicity occurred at 446 µg/kg/hr. Toxicity included a transient asymptomatic decrease of mean arterial blood pressure (more than 15 mmHg) and/or an asymptomatic increase of methemoglobin level above 5%. Nitrite, nitrate, S-nitrosothiols concentrations in plasma and whole blood increased in all subjects and returned to preinfusion baseline values within 12 hours after cessation of the infusion. The mean half-life of nitrite estimated at maximal tolerated dose was 45.3 minutes for plasma and 51.4 minutes for whole blood. CONCLUSION: Sodium nitrite can be safely infused intravenously at defined concentrations for prolonged intervals. These results should be valuable for developing studies to investigate new NO treatment paradigms for a variety of clinical disorders, including cerebral vasospasm after subarachnoid hemorrhage, and ischemia of the heart, liver, kidney and brain, as well as organ transplants, blood-brain barrier modulation and pulmonary hypertension. CLINICAL TRIAL REGISTRATION INFORMATION: http://www.clinicaltrials.gov; NCT00103025

CXCR2 Inhibition Combined with Sorafenib Improved Antitumor and Antiangiogenic Response in Preclinical Models of Ovarian Cancer

The authors thank Drs. Kar-Ming Fung and Muralidharan Jayaraman, and Ms. Sheeja Aravindan for their help with the IHC experiments. The authors also thank the OUHSC Histology and Molecular Imaging Cores for their service and technical assistance.Antiangiogenic therapy is important for the treatment of gynecological cancer. However, the therapeutic benefit derived from these treatments is transient, predominantly due to the selective activation of compensatory proangiogenic pathways that lead to rapid development of resistance. We aimed to identify and target potential alternative signaling to anti-vascular endothelial growth factor (VEGF) therapy, with a view toward developing a combination of antiangiogenic agents to provide extended therapeutic benefits. We developed a preclinical in vivo phenotypic resistance model of ovarian cancer resistant to antiangiogenic therapy. We measured dynamic changes in secreted chemokines and angiogenic signaling in tumors and plasma in response to anti-VEGF treatment, as tumors advanced from the initial responsive phase to progressive disease. In tumors that progressed following sorafenib treatment, gene and protein expression levels of proangiogenic CXC chemokines and their receptors were significantly elevated, compared with responsive tumors. The chemokine (C-X-C motif) ligand 8 (CXCL8), also known as interleukin-8 (IL-8) increase was time-dependent and coincided with the dynamics of tumor progression. We used SB225002, a pharmacological inhibitor of chemokine (C-X-C motif) receptor 2 (CXCR2), to disrupt the CXC chemokine-mediated functions of ovarian cancer cells in in vitro assays of cell growth inhibition, spheroid formation, and cell migration. The combination of CXCR2 inhibitor with sorafenib led to a synergistic inhibition of cell growth in vitro, and further stabilized tumor progression following sorafenib in vivo. Our results suggest that CXCR2-mediated chemokines may represent an important compensatory pathway that promotes resistance to antiangiogenic therapy in ovarian cancer. Thus, simultaneous blockage of this proangiogenic cytokine pathway using CXCR2 inhibitors and the VEGF receptor (VEGFR) pathway could improve the outcomes of antiangiogenic therapy.Yeshttp://www.plosone.org/static/editorial#pee

Development of Prodrugs for PDT-Based Combination Therapy Using a Singlet-Oxygen-Sensitive Linker and Quantitative Systems Pharmacology

Photodynamic therapy (PDT) has become an effective treatment for certain types of solid tumors. The combination of PDT with other therapies has been extensively investigated in recent years to improve its effectiveness and expand its applications. This focused review summarizes the development of a prodrug system in which anticancer drugs are activated locally at tumor sites during PDT treatment. The development of a singlet-oxygen-sensitive linker that can be conveniently conjugated to various drugs and efficiently cleaved to release intact drugs is recapitulated. The initial design of prodrugs, preliminary efficacy evaluation, pharmacokinetics study, and optimization using quantitative systems pharmacology is discussed. Current treatment optimization in animal models using physiologically based a pharmacokinetic (PBPK) modeling approach is also explored

Pharmacokinetics and interspecies scaling of a novel, orally-bioavailable anti-cancer drug, SHetA2 - Fig 3

<p>The plasma concentration-time profiles of SHetA2 following (A) 20 mg/kg IV dose and oral dose of 20 and 60 mg/kg in in mice (n = 3/dose), (B) 5 mg/kg IV dose and oral dose of 100, 500, and 2000 mg/kg in rats (n = 3/dose), and (C) 5 mg/kg IV dose (n = 2) and oral dose of 100, 400, and 1500 mg/kg (n = 4/dose) in dogs. Solid lines indicate the model-predicted values after simultaneous fitting of IV and oral PK data to the proposed PK models in each species. Symbols indicate the observed plasma concentrations (mean ± sd).</p

Phenotypic resistance to anti-VEGFR therapy in a SKOV-3 ovarian cancer xenograft mouse model.

<p><b>A)</b> SKOV-3 xenografts were treated for eight weeks with 30 mg/kg sorafenib via daily oral gavage. Controls were treated with the treatment vehicle alone. Tumor volumes were measured twice a week and are represented as mm³ ± SEM. Out of 19 mice, 10 developed resistance to the sorafenib treatment. Black, red, and green lines indicate the mean tumor volume progressions of control, SR, and SS mice, respectively. A significant difference in tumor volume (* <i>P</i> < 0.05) was observed between the treatment-resistant and-sensitive groups, starting at week five of treatment. SS = sorafenib-sensitive; and SR = sorafenib-resistant. B) Representative immunostaining for CD-31 (top row), and Ki-67 (bottom row) in control, sorafenib-sensitive (SS), and sorafenib—resistant (SR) tumors. C) Vessel density (CD-31) and proliferation index (Ki-67) were significantly increased in sorafenib-resistant tumors compared with the sorafenib-sensitive tumors.</p

CXCR2 inhibition <i>in vivo</i> stabilizes progression of sorafenib-resistant tumors.

<p>SKOV-3 xenografts were treated with a daily dose of 30 mg/kg sorafenib until tumors developed phenotypic resistance to the treatment (~46 days). Mice with resistant tumors were then randomized into groups to receive one of the following: 30 mg/kg sorafenib alone (<i>n</i> = 6), 10 mg/kg SB225002 alone (<i>n</i> = 6), or sorafenib plus SB225002 (<i>n</i> = 6). The arrow indicates the start of treatment on day 46. Tumor volume was measured at the indicated times and is presented as mean ± S.D. The sorafenib and SB225002 combination led to 42% reduction in tumor growth compared with sorafenib alone (<i>P</i> < 0.05).</p

<i>In vitro</i> effects of combined SB225002 and sorafenib.

<p>SB225002 significantly enhanced the growth inhibition effects of sorafenib on SKOV-3 (A) and HUVEC (B) cells. A) A combination of 10 μM sorafenib and 4 μM SB225002 synergistically inhibited the growth of SKOV-3 cells, compared with each drug alone (<i>P</i> < 0.005). B) A combination of 4 μM sorafenib and 2 μM SB225002 synergistically inhibited the growth of HUVEC cells, compared with each drug alone (<i>P</i> < 0.01). C) Representative images of tube formation assay of HUVECs treated with or without 1 μM SB225002 or 2 μM sorafenib. Tube formation was analyzed using Wimtube analysis software and tube length is presented in pixels. Addition of SB225002 to sorafenib treatment induced a statistically significant decrease in HUVECs tube formation (<i>P</i> < 0.005). Data are shown as mean tube length in pixels ± S.D. of three independent experiments. D) Representative images of HUVECs migration assay using transwell chamber. To quantitate migratory cells, three independent fields of migratory cells per well were photographed under the phase contrast microscope. The number of cells per field was counted and averaged. Cell counts are expressed as relative number of cells migrated to lower side of the transwell chamber with the results from control cells given as 1. The inhibitory effect of sorafenib (2 μM) on migration was significantly enhanced by 1 μM SB225002 (<i>P</i> < 0.01). E) Spheroidal growth is impaired by CXCR2 inhibition in SKOV-3 cells. Spheroid areas were measured using ImageJ software. The values represented on the y axis are pixels ± S.D. of three independent experiments.</p

Log dose vs. oral bioavailability among mice (●), rats (■), and dogs (▲) showing the maximum extent of absorption of 18.6% at doses <100 mg/kg.

<p>Log dose vs. oral bioavailability among mice (●), rats (■), and dogs (▲) showing the maximum extent of absorption of 18.6% at doses <100 mg/kg.</p

Simulated human PK profile of SHetA2 at 10 mg/kg obtained from 100 virtual subjects in the population simulator of GastroPlus with a two-compartment PK model with physiologically-based gut absorption model for humans.

<p>The solid line shows the mean concentrations and the shaded portion shows the 90% probability contour for the spread of concentrations around the mean.</p