A CD&D

A commonly used medication that prevents blood clots from forming may also prevent existing clots from damaging delicate vein walls – and may accelerate healing in a clot-damaged area of vein wall, according to new research from the University of Michigan (U-M) Cardiovascular Center (Ann Arbor, Michigan).

The findings, made in laboratory mice, add evidence to support the aggressive anti-clot efforts now under way at American hospitals and nursing homes, according to the researchers. These efforts are aimed at preventing many of the 300,000 deaths that occur each year when clots break free of vein walls and travel to the lungs.

The study, published in the March issue of the Journal of Vascular Surgery, looked at the impact of low-molecular weight heparin (LMWH), an anti-clotting medication different from the unfractionated form of heparin that has recently been the subject of safety concerns.

The results can't immediately be translated into human patients, the researchers acknowledge, but they say they help illuminate the process by which LMWH works, including the potential advantages of pre-treatment in at-risk patients, or early treatment of patients in whom a DVT has formed.

"Hospitalized patients who are on prophylactic heparin can still develop clots, but these results suggest that having heparin 'on board' can lessen the long-term impact of a DVT," said senior author Peter Henke, MD, aassociate professor in the U-M Section of Vascular Surgery. "At the same time, our findings also suggest that rapid heparin treatment after a DVT forms is important for long-term healing."

Henke and colleagues created venous clots in laboratory mice, and studied how the size of the clot, the damage inflicted on the vein wall, and the natural repair process in the cells of the vein wall changed over time. Some of the mice received LMWH before the clot was formed, while others received it afterward. Another group of mice received no heparin.

"Mice that received LMWH before their clot formed went on to experience a much faster and more complete healing process, compared with those that received LMWH only after the clot was formed and those that didn't receive the drug," says Henke. "And among those that received LMWH only after the clot was formed, the mice that got treated the soonest after clot formation healed the fastest and most completely."

The experiments, performed in U-M's Conrad Jobst Vascular Surgery Research Laboratory, simulated a human condition called deep-vein thrombosis (DVT), a condition suffered by a million Americans each year.

About half go on to develop a PE, which causes sudden symptoms and must be treated immediately. Still, more than half of PE patients will die – making the condition one of the most preventable causes of death among hospitalized patients.

LMWH is increasingly prescribed to hospitalized patients who might be at risk of developing DVTs and PEs, especially older people, surgical patients, and people with a personal or family history of clotting problems. DVTs are especially likely to form in legs that are immobile for long periods of time – a condition frequently seen in long air flights – that have been injured, or that have poor circulation.

As the body's own repair mechanisms break down the clot, they often leave behind a small patch of damaged vein wall that is never fully repaired, and interferes with the vein's ability to push blood back up to the heart, called chronic venous insufficiency. The damaged area may also be more hospitable for future clot formation.

It's already known that LMWH helps encourage the breaking up of clots, and prevents new ones from forming. So, the U-M researchers, led by Henke and former U-M medical student Daria Moaveni, MD, set out to see how the cells of the vein wall, or endothelium, react to a DVT when the drug is present.

They first studied the "natural history" of DVTs by performing detailed molecular analyses of the vein wall tissue in the area of a clot after one, four and 14 days. They found that the clots grew over the first four days, then began to shrink as the body's repair mechanisms kicked in. VIA staining, the researchers could see endothelial cells and vascular smooth muscle cells dying off immediately after clot formation, and then saw new ones growing in the vein lining in the clot-damaged area.

Then, the researchers induced DVTs in the three groups of mice in the heparin experiment. The mice that received LMWH before the DVT formed had the fastest endothelial repair, followed by those that received LMWH soon after the DVT was induced. The biggest difference was seen at four days after the DVT formed, but by day 14 the two heparin-treated groups of mice had about the same extent of repair. The pre-treated mice had the greatest recovery of the vein wall lining.

Using real-time polymerase chain reaction tests, the researchers were also able to look at patterns of gene expression in harvested veins in culture. As with the cell staining, they saw signs that the pre-treated mice reacted in a way that suggested fastest recovery.

The new findings are supported by a previous U-M study, published in Thrombosis and Haemostasis in 2007, showing that the longer a clot is in contact with a vein, the worse the damage.

Now, the team is studying the proteins in the vein wall that are involved in promoting endothelial health and regeneration after an injury or other insult. They're also working on the clinical level to increase the appropriate use of preventive measures among patients hospitalized at U-M. A new standardized risk-factor assessment tool is now in use among all surgical patients, and will soon be used in all U-M hospital patients, to determine which patients need clot-preventing measures the most.

Ibuprofen found to inhibit stroke-inhibition of aspirin

Stroke patients who use ibuprofen for arthritis pain or other conditions while taking aspirin to reduce the risk of a second stroke undermine aspirin's ability to act as an anti-platelet agent, researchers at the University at Buffalo (UB; Buffalo, New York) conclude.

In a cohort of patients seen by physicians at two offices of the Dent Neurologic Institute (Buffalo), 28 patients were identified as taking both aspirin and ibuprofen (a nonsteroidal anti-inflammatory drug, or NSAID) daily and all were found to have no anti-platelet effect from their daily aspirin.

Thirteen of these patients were being seen because they had a second stroke/TIA while taking aspirin and a NSAID, and were platelet non-responsive to aspirin (aspirin resistant) at the time of that stroke.

The researchers found that when 18 of the 28 patients returned for a second neurological visit after discontinuing NSAID use and were tested again, all had regained their aspirin sensitivity and its ability to prevent blood platelets from aggregating and blocking arteries.

The study is the first to show the clinical consequences of the aspirin/NSAID interaction in patients being treated for prevention of a second stroke, and presents a possible explanation of the mechanism of action.

The FDA currently warns that ibuprofen might make aspirin less effective, but it also has said that the clinical implications of the interaction have not been clinically evaluated.

"This interaction between aspirin and ibuprofen or prescription NSAID's is one of the best-known, but well-kept secrets in stroke medicine," said Francis Gengo, PharmD, the study's lead researcher.

"It's unfortunate that clinicians and patients often ar eunaware of this interaction. Whatever number of patients who have had strokes because of the interaction between aspirin and NSAIDs, those strokes were preventable."

Gengo is professor of neurology in the UB School of Medicine and Biomedical Sciences and professor of pharmacy practice in the UB School of Pharmacy and Pharmaceutical Sciences. Results of the study were published in the January issue of the JournalClinical Pharmacology. "We first looked at this issue way back in 1992 in a study conducted in normal volunteers, but it was published as an abstract only," he said. "We never followed through with a manuscript, but another group published an elegant study in the New England Journal of Medicine showing this interaction at least seven years ago.

"When we began to assess this in our stroke patients, a surprisingly high percentage of a group of 653 patients, around 17%, were taking aspirin plus Motrin [a brand of ibuprofen].

"The prescription medication Aggrenox, which also is used for secondary stroke prevention and contains aspirin and extended release dipyridamole, is affected the same way as aspirin," Gengo continued. "In preventing strokes, it is statistically a little better than aspirin but more expensive."

But he said that one of the most common side effects after a person starts taking you first start taking Aggrenox is headache, "so some physicians, pharmacists or physician assistants tell patients to take a Motrin so they don't get a headache. This likely would negate the effects of the aspirin and extended release dipyridamole. Those patients might as well take this expensive drug and flush it down the toilet."

Gengo and colleagues verified with urine testing that all 18 patients, six men and 12 women, were taking their aspirin or aspirin and extended release dipyridamole as directed. Information on the concomitant use of NSAIDS was obtained from patient interviews. Data from the earlier healthy volunteer study showed the magnitude and time course of each drug administered separately, as well as in combination.

The UB study provides important information, Gengo said, because in most previous studies, measurements were taken only at one point in time, and that time point may have been during the four- to six- hour window when concentrations of NSAIDS were sufficiently high to inhibit aggregation.

"Our data report the entire time course of this interaction," he said. "The results showed that platelets resumed aggregating within four to six hours when aspirin and ibuprofen were taken close together, leaving patients with no anti-platelet effect for 18-20 hours a day. Normally, a single dose of aspirin has an effect on platelet aggregation for 72-96 hours," Gengo said.

"When I lecture to pharmacy students, I tell them, 'Please, you have a responsibility to the patients you care for. When you counsel a patient taking aspirin/extended release dipyrdamole to lower stroke risk, tell patients they may have some transient headaches, but to avoid ibuprofen. You may have prevented that patient from having another stroke.'"

Cardium reports progress With DNA-based protocol

Cardium Therapeutics (San Diego) reported positive findings from its preclinical study conducted by researchers at Emory University (Atlanta), which demonstrated highly efficient uptake of DNA-based vectors within acutely ischemic myocardium (heart muscle lacking sufficient blood flow as a result of blockage of the coronary arteries).

The study employed an occlusion and reperfusion model analogous to a heart attack or acute myocardial infarction, in which the coronary arteries supplying the heart muscle are initially blocked and later reopened, as occurs in patients after a heart attack. In that setting, delivery of an adenovector using Cardium's intracoronary administration technique resulted in robust protein expression within acutely ischemic areas of the myocardium that are most at risk for damage following a heart attack.

In addition to showing high levels of uptake, there was no evidence of any increase in inflammatory responses following intracoronary infusion to the acutely ischemic heart as compared to controls.

The study was designed to further support the therapeutic potential of Corgentin (Ad5IGF-I) to preserve heart tissue and cardiac function following a heart attack and was conducted at Emory University under support of an NIH Small Business Innovation Research grant.

Corgentin is a DNA-based therapeutic designed to provide localized and sustained cardiac production of insulin-like growth factor-I (IGF-I) following a single intracoronary administration in an acute care setting after percutaneous coronary intervention to restore blood flow in heart attack patients.

Numerous studies have shown that ongoing damage to cells within the infarct zone continues to occur even after blood flow has been restored, a phenomenon known as reperfusion injury. Corgentin is intended to enhance myocardial healing in and around the infarct zone when used as an adjunct to existing pharmacologic and interventional therapies.

Results of the study indicate that non-surgical intracoronary infusion of an adenovector carrying a reporter gene to the heart enables robust protein expression in the area of the myocardium at risk due to ischemia and reperfusion injury.

The recently completed preclinical development study follows an earlier pilot study using a similar myocardial infarct model in which intracoronary administration of Ad5IGF-I was found to preserve heart tissue and function following an acute myocardial infarction.

Christopher Reinhard, CEO and chairman of Cardium, said that the results "confirm that our intracoronary infusion approach can be used to successfully deliver therapeutic adenovectors into acutely ischemic myocardium such as occurs after a heart attack, at very high efficiency, without the need for any needle injections into the myocardium. Confirmation that non-surgical adenovector delivery through a standard catheter such as those used routinely for angiography can effectively target the acutely diseased heart substantially advances our Corgentin development program.

"The highly effective delivery to acutely ischemic myocardium following intracoronary infusion extends the findings of high first pass uptake of Generx in the hearts of patients with chronic ischemia as observed in the AGENT-1 clinical study, and underscores the potential of these approaches to be applied to the treatment of various forms of heart disease."

Ad5IGF-I is a next-generation DNA-based therapeutic using the insulin-like growth factor-I gene carried by an adenovector that is being developed as a potential one-time treatment to promote the preservation and restoration of heart tissue and cardiac function following an acute myocardial infarction (MI).

Cardium says the inherent biological properties of IGF-I, which include inhibition of cardiomyocyte apoptosis, adaptive cardiomyocyte hypertrophy, recruitment of cardiac progenitor cells, as well as the induction of angiogenesis and enhancement of cardiac function, combined with Cardium's delivery approach to yield sustained localized expression, provide the rationale for the development of a therapy directed at myocardial repair and restoration. T

his combination of positive biological attributes and effective delivery supports the potential of Corgentin to improve functional recovery and prevent ventricular dysfunction and the associated progression to congestive heart failure following myocardial infarction and reperfusion.

The safety of systemic IGF-I protein therapy has been confirmed in multiple human clinical studies for a number of medical indications, and has been approved by the FDA for long-term use in children in connection with Tercica's Increlex product (generic mecasermin).

While considered generally safe, systemic IGF-I protein delivery is not believed to effectively target cardiomyocytes and other critical cells within the heart in a localized and sustained manner. Preclinical studies suggest that by targeting the heart using intracoronary infusion of DNA-coded, myocardial-directed delivery, using the methods pioneered for Cardium's Generx development program, Corgentin has the potential to induce a positive biologic response in affected heart muscle. The targeted cells are believed to produce therapeutic protein levels directly in the myocardium where it is needed.

There have been an estimated 1,000 patients that have been treated with various dose levels of IGF-I protein, and now over 450 patients who have received Generx (Ad5FGF-4, alferminogene tadenovec, a DNA-based angiogenic growth factor) via intracoronary administration. We believe the safety and preliminary efficacy from these studies provide further support for the clinical potential of Corgentin.

Cardium and its subsidiaries, InnerCool Therapies (San Diego) and the Tissue Repair Company (San Diego), are primarily focused on therapeutic products and devices for cardiovascular, ischemic and related indications.

Briefly ...

• Osiris Therapeutics (Columbia, Maryland) said that interim results at the one-year time point in the company's Phase I trial of Prochymal in heart attack patients continued to demonstrate a strong safety profile and to show statistically significant improvement in heart function. Results of the 53-patient study showed that the Prochymal treatment group achieved a statistically significant 5.2-point increase in left ventricular ejection fraction (based on MRI studies) over baseline vs. the 1.8 point improvement seen in the placebo group.

Data also indicated that patients with more severe myocardial infarction, defined as a baseline LVEF of 45 or less, demonstrated even greater effects, with the Prochymal group showing a 6.5-point improvement one-year post-treatment, compared to a 1.9-point increase in the placebo group.

Based upon those results, the company has received FDA approval to start a Phase II trial.

• Cytos Biotechnology (Zurich, Switzerland) reported publication of positive results from a Phase IIa clinical trial with the hypertension vaccine CYT006-AngQb. In the study of hypertensive patients, vaccination with CYT006-AngQb was shown to significantly reduce the mean ambulatory daytime blood pressure by induction of antibodies that bind angiotensin II. Data were published in the March 8 issue of The Lancet.

• Palatin Technologies (Cranbury, New Jersey) reported completing a Phase I clinical trial of PL-3994, a novel, long-acting natriuretic peptide receptor A (NPRA) agonist under development for treatment of acute decompensated congestive heart failure. The evaluations included safety, tolerability, pharmacokinetics and several pharmacodynamic endpoints, including levels of cyclic guanosine monophosphate (cGMP), a natural messenger nucleotide. Dosing concluded with the achievement of the primary endpoint of the study, a prespecified reduction in systemic blood pressure.

No volunteer experienced a serious or severe adverse event. Elevations in plasma cGMP levels, increased diuresis (urine excretion) and increased natriuresis (sodium excretion) were all observed for several hours after single subcutaneous doses. The company said that data analysis is ongoing and will be submitted for presentation when completed.

• Amgen (Thousand Oaks, California) reported that the European Commission decided to amend the prescribing information for Aranesp (darbepoetin alfa), based on the positive opinion from the Committee for Medicinal Products for Human Use. In January, the CHMP granted positive opinions for all centrally authorized erythropoiesis-stimulating agents (ESAs) in the European Union.

Some of the key changes include:

– stipulating a uniform target hemoglobin range of 10 g/dL to 12 g/dL, with guidance to avoid sustained hemoglobin levels above 12 g/dL;

– adjusting dosages to maintain hemoglobin concentration between 10-12 g/dL once the therapeutic objective for an individual patient has been achieved;

– and amending the special warnings to indicate that ESAs have not been shown to improve overall survival or decrease the risk of tumor progression in patients with anemia associated with cancer.

• NicOx (Sophia Antipolis, France) said it has begun two large clinical pharmacology studies in the U.S. that will assess the blood pressure profile of naproxcinod compared to ibuprofen and naproxen.

The primary objective of the studies is to assess the mean change from baseline in the average 24-hour systolic blood pressure, as well as to evaluate the general safety and tolerability of naproxcinod. Those separate studies, 12 and 16 weeks in duration, will recruit a total of around 420 osteoarthritis patients with controlled hypertension.

• Trophos (Marseille, France) has been awarded a two-year, $1.4 million grant for preclinical studies of TRO40303 in cardiac and cerebral ischemia-reperfusion injury. The grant was provided by the French research agency, Agence Nationale pour la Recherche (ANR). Clinical trials of TRO40303 are expected to begin in 2009.