Altering Anti-Thrombosis Discovery Models to Examine Pro-Thrombotic Activity from a Safety Perspective

Posted by CorDynamics on January 18th, 2016

Pro-Thrombotic Activity

Thrombosis, the process through which blood forms a clot, is a two-way street. It protects us from major bleeding following even minor injuries, yet is responsible for over ten million deaths globally every year via heart attacks and strokes.

Over the years we’ve conducted many preclinical thrombosis studies examining the effects of established and potential ANTI-thrombotic agents. Increasingly, a number of clients have asked for the development of slightly altered models to screen compounds for any PRO-thrombotic activity.

This new data set marks our evolution of anti-thrombosis discovery investigations into pro-thrombotic safety models, focusing on our ability to create a pro-thrombotic window. Clearly, pro-thrombotic activity is an undesirable property for drugs outside the cardiovascular arena.

See data.

Although our large animal anti-thrombotic models (including the electrolytic injury paradigms) are well characterized in a traditional efficacy mode, it is challenging from a resource perspective to scale those preparations to screen multiple compounds rapidly. As such we’ve been modifying our rodent models of arterial thrombosis – namely, the FeCl3 mouse – for a prothrombotic screening setting.

Briefly, we dose mice with either vehicle or active test article for the specified period prior to administration of reduced levels of FeCl3 to the external surface of the carotid artery. In most mice, the reduced levels of FeCl3 will cause instability in arterial blood flow – but not be associated with significant occlusion (formation of thrombus). Test article pro-thrombotic activity may be quantitated as reductions in arterial blood flow along with increasing incidence of occlusion.

More on thrombosis.

 

 

Filed under: Drug Discovery Services, Drug Safety Services, Thrombosis | No Comments

Industry Weighs in on CIPA, PAH and More

Posted by CorDynamics on November 04th, 2015

Getting out of the lab and networking with colleagues to check the pulse of the industry is central to our resource and development planning.

The CorDynamics team returned last month from a very productive Safety Pharmacology Society exhibition in Prague, Czech Republic. The mood was very upbeat, with many clients and friends expressing satisfaction with the positive state of our industry. We’ve always enjoyed the rotating geographic nature of this particular meeting – splitting time biennially between Europe and North America. This year, we appreciated that many of the over 450 attendees stopped by our booth to catch up and discuss the current state of the pharma industry.

As expected, many safety pharmacology issues were discussed and several included topics we’ve seen before.

Safety Pharmacology Hot Topics Heading Into 2016

Glasses On Scientfic Paper Isolated On White

Comprehensive In Vitro Pro-Arrhythmia Assay (CIPA)

While it remains to be seen exactly what the final scheme will look like, it’s clear the comprehensive in vitro proarrhythmia paradigm will continue to hold the torch as a leading area for discussion – and spirited debate – for the foreseeable future. We agree with a number of colleagues who purported the benefits of a complete preclinical integrated cardiovascular risk assessment vis-a-vis decision making. (Learn more about integrated risk assessments alongside CIPA.)

Integrative Pharmacology and Translation to the Clinic

The focus on integrative pharmacology with an eye toward the clinic is a welcomed and embraced narrative. The SPS agenda included cardiovascular symposia on drug interactions with baroreceptor function, models in anti-diabetics, along with a clinical perspective on severe cardiopulmonary disease. We presented some very recent data on the interventional use of both Riociguat and sildenafil against established PAH in the hypoxia/VEGF antagonist model.

Click here to learn more about our PAH work.

Filed under: Drug Safety Services | No Comments

Cardio-Oncology: Where Safety Pharmacology Fits In

Posted by CorDynamics on June 23rd, 2015

Earlier this month I attended an excellent Safety Pharmacology Society regional meeting at Pfizer-La Jolla focused on cardio-oncology and safety pharmacology.

Dr. Lori Minasian, Chief of the Community Oncology and Prevention Trials Research Group Program and the National Cancer Institute of the National Institutes of Health (NIH), opened the conversation by reminding us we should feel some sense of accomplishment at being able to worry about the cardiovascular side effects of cancer treatment. She pointed out that in the not too distant past, chemotherapy had not generally been associated with levels of efficacy that would provide either time or a framework for such concern.

She pointed out that we are now in a new age where targeted and specific drugs are increasing survival with fewer toxic side effects – allowing us to have the “luxury” of holding such discussions. (Her clinician – and patient – perspective was a welcomed perspective that is often missing from these seminars and scientific meetings.)

Substantive data from case studies of compounds in this ‘new age’ were examined, including VEGF and MEK inhibitors among others.

In general we are concerned about downstream effects of hypertension and cardiac dysfunction, with a pinch of QT prolongation for good measure.  More on cardiovascular toxicity in cancer drugs.

The regulatory and industrial perspectives on how to handle these issues were covered at the meeting as well. Dr. Darrell Abernathy from the USFDA detailed thoughts on using a “systems pharmacology” approach for predicting and evaluating cardiac safety signals. Scientists from Pfizer and Novartis discussed their testing schemes that included preclinical models such as Langendorff isolated hearts, telemetry and echocardiography.

Promising Takeaways

  • The cardiovascular effects of these newer anti-cancer agents can be modeled in a preclinical fashion.
  • The more we know about the multi-faceted profile of these agents, the better chance we have to simultaneously treat the disease while working to mitigate any side effects.

 

Filed under: Drug Safety Services, Langendorff Heart, Preclinical Consulting Services, Telemetry | No Comments

How to Screen for Vasoactivity Efficiently and Affordably

Posted by CorDynamics on May 18th, 2015

Vascular rings are an effective way to analyze vasoreactivity—using contraction and relaxation as arbiters of increased or decreased blood pressure.

These experiments can be conducted rapidly in multiple species, with a streamlined study design to examine compounds efficiently and inexpensively. Most studies use approximately 5 mg of test article total, and can be completed within a matter of days.

This assay can answer a variety of safety pharmacology questions. Do compounds from a certain chemical series cause vasoconstriction or vasorelaxtion? Could this indicate an increase or decrease in arterial blood pressure? Can we differentiate a vascular effect from a direct cardiac effect?

Slide1

View Data

Project teams often ask us if they should leverage telemetry in these scenarios?

Telemetry screening can certainly probe these questions.

However, going in vivo for these screening assessments can be impractical for clients for a number of reasons:

• Chemical supply restricted to a few milligrams

• Budgets limited in scope at an early stage

• Compounds too numerous to screen reasonably in vivo

Contraction/Relaxation in Vascular Rings Capabilities

• Multi-channel Radnoti systems coupled to state of the art ADInstruments data acquisition platforms.

• Continuous recording of vascular tone from a variety of vessel types, including aortic rings in addition to other vascular sampling sites.

• Critical parameter reports–amplitude, time of contraction, time to half-contraction (relaxation), average/max activity.

For clients with lead compounds producing vasoactive responses in vivo, we recommend screening related and backup molecules using our vascular ring model.

The model is also effective for concentration response studies with frontrunner compounds to provide perspective alongside additional in vivo data.

Regardless of the impetus, these in vitro studies enable quick and sound decisions when selecting compounds for advancement.

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Does the FDA Refer to Disease-State Models to Determine Safety?

Posted by CorDynamics on April 22nd, 2015

The answer is: sometimes.

FDA Orphan Drugs Rare Diseases Cholesterol

A few months ago I attended an excellent Safety Pharmacology Society webinar (Nov 2014, “Cardiac Safety Testing Models”) where the non-clinical examination of cardiac contractility was discussed.

Dr. Philip Gatti, from the US FDA, concluded that compounds with putative inotropic effects should undergo “better utilization of in vitro systems (Langendorff or wedge preps) or use of animal models of heart failure which would enhance sensitivity to such drug effects.

Our labs have interrogated the cardiovascular effects of test articles in a variety of underlying pathophysiological states, including subjects with hypertension to those with impaired respiratory capacity.

One of the more frequent drug safety conditions we are asked to model is the compromised or failing heart. Many project teams need to know if their compounds affect left ventricular hemodynamics in the presence of pre-existing cardiac dysfunction. Sometimes these properties may not exist in the normal subject. However, they may be present in the target population.

We have conducted these studies using multiple models, including the post-infarcted heart, hypertrophy following hemodynamic overload (such as transverse aortic constriction), and tachypaced-induced cardiomyopathy.

Similar questions are usually asked:

  • Is it appropriate to examine drug safety in animals with ‘disease-state’?
  • Is this a current regulatory expectation?
  • Is there a differential effect compared to ‘normal’ animals?

Using these approaches, we have uncovered substantive areas of concern while also mitigating issues that previously appeared insurmountable.

We know there is an important role for using the ‘disease-state’ subject in cardiovascular safety pharmacology assessments.

While most preclinical studies will continue to use normal animals for risk assessment, the inclusion of disease models where appropriate can help unmask notable toxicities that may only occur in the target patient population.

Filed under: Drug Safety Services, Heart Failure, Hemodynamics, Langendorff Heart | No Comments

Questioning QT Interval Measurements? Look at the Anesthetic: Part 2

Posted by CorDynamics on March 16th, 2015

QT Questions Look at Anesthetic

CorDynamics will be presenting a poster at the upcoming 2015 Society of Toxicology meeting in San Diego entitled: The Differential Effect of Nembutal and Ketamine/Xylazine Anesthetic on Dofetilide-Induced QT Interval Prolongation. 

The objective was to advance upon our previous findings presented at SOT last year. (Read Part I: When Questioning QT Interval Measurements: Look at the Anesthetic.) This model examines the effects of dofetilide, an IKr antagonist known to prolong QT interval, on guinea pigs anesthetized with either Nembutal or ketamine/xylazine.

The anesthetized guinea pig is a widely used model for early screening of drug-candidate effects on cardiovascular function. This species also continues to gain traction for use in conscious telemetry screening.

In this study, we found that administration of dofetilide to either Nembutal or ketamine/xylazine anesthetized guinea pigs significantly increased QTcB interval at all doses tested compared to time-matched vehicle control. QTcB interval increased up to 22% in the Nembutal group, yet only reached 12% in the ketamine/xylazine group even though the dose was increased 5-fold in the latter cohort. There were no effects on mean arterial pressure, heart rate, or other ECG parameters in either group.

View Poster

Our data demonstrate that sodium pentobarbital anesthetized guinea pigs are more sensitive to QTc interval prolongation than ketamine/xylazine animals.

Our Conclusion

Consideration should be taken when selecting anesthetics for the guinea pig cardiovascular model. Sodium pentobarbital should be the anesthetic of choice when screening compounds for the potential to prolong QTc interval.

Filed under: Anesthetized Models, Telemetry | No Comments

Data on Cholesterol Not Always Easy to Explain

Posted by CorDynamics on February 16th, 2015
by Dr. Michael Gralinski, CorDynamics CEO

A cardiovascular news story came out recently and the context of its release was troublesome to me. This article, not surprisingly carried by all major news organizations given the bold proclamation, announced ‘cholesterol may not be as bad as we thought’.

As I read through this piece, I came to the conclusion that we as scientists need to better articulate the actual point of our research and clearly explain our data. In the absence of a clear direction from the scientists, an attention-grabbing headline often misses the mark.

Reading the article, if I hadn’t known better, I would have come away believing cholesterol “was wrongly linked to heart disease” and many guidelines from the government and other advisory bodies were incorrect for decades. The actual findings of the research are quite different from that characterization.

Cholesterol, and specifically LDL/its isoforms, is a substantive contributor to coronary artery disease and stroke. The point of the research not reported in the story was that our bodies produce levels of cholesterol mostly independent of the amount consumed through the diet. Therefore, it may not be as important to highly regulate the amount we are eating – but instead focus on methods to reduce plasma cholesterol/LDL such as exercise, a diet high in fiber or medications if needed.

For decades statins were considered the final weapon in the battle against cholesterol. Unfortunately, we now know this is not the case. Unanticipated side effects following years of exposure, along with greater understanding of hypercholesterolemia’s  pathogenesis, have resulted in a need for new programs in this field – including PCSK9 and BAT inhibitors amongst others.

Compounds from these programs will be under careful scrutiny for undesirable action that has de-railed previous cholesterol projects such as blood pressure increases with CETP inhibition. More on related drug safety studies.

In addition, prudent examination of the large databases have not shown a proven beneficial effect for lowering cholesterol to certain numerical targets. Lifestyle modifications may thus continue to play a large role in lowering overall risk of heart disease prior to pharmacological treatment.

Understanding how to interact with colleagues outside of our field is a skill set needing improvement for many scientists. Explaining our data and what we do is key–whether talking to project teams, investors, clients or simply friends and neighbors.

 

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Efficacy with PAH Clinical Drugs in Modified Gold Standard Preclinical Assessment

Posted by CorDynamics on January 13th, 2015

Riociguat Reduces Pulmonary Arterial Hypertension in Hypoxia-Semaxanib Intervention Model

Our laboratories recently conducted experiments examining whether riociguat – approved by the FDA for PAH in 2013 – along with sildenafil could intervene against established hypoxia-semaxanib mediated pulmonary arterial hypertension (PAH) in the rat.

Our research team has already reported on the effects of numerous positive controls including sildenafil, bosentan, bestatin and tadalafil using a prevention mode.

These intervention-focused experiments were novel since riociguat or sildenafil were dosed daily beginning 4 weeks after the initiation of PAH.

Riociguat Reduce Pulmonary Arterial Hypertension in Hypoxia-Semaxanib Intervention Model

View Data

The data demonstrate a 21% reduction in pulmonary artery pressure following 4 weeks of intervention with riociguat (42% decrease with sildenafil). In addition, right ventricular hypertrophy was decreased 20% in the riociguat cohort vs. vehicle (sildenafil – 22% reduction).

Examining these clinically utilized compounds in both prevention and intervention modes provides clients with an enhanced, translatable model of pulmonary arterial hypertension.

 

Filed under: Drug Discovery Services, Pulmonary Arterial Hypertension | No Comments

Leveraging the Langendorff Model to Detect Proarrhythmia

Posted by CorDynamics on November 20th, 2014
by Dr. Michael Gralinski, CorDynamics CEO

I spent last week with the CorDynamics team exhibiting at the American College of Toxicology meeting in Orlando.

A timely symposium on the ongoing CiPA (Comprehensive In Vitro Proarrhythmia Assay) initiative brought out a number of questions from attendees as they visited the CorDynamics booth. I enjoyed the lively discussion on various methods and approaches to tackle the concept of proarrhythmia prediction.

Recognizing the nascent status of CiPA, earlier this year we redesigned our standard rabbit Langendorff isolated heart assessments to be conducted with a much greater emphasis on proarrhythmia – while still capturing vital details on cardiac hemodynamics, electrocardiography, and electrophysiology. 

To do this, we perform Langendorff experiments amenable to a wide range of simulation frequencies.

First, we use advanced metrics:

  • instantaneous monophasic action potential variability
  • temporal characteristics of the electrocardiographic T wave
  • development of afterdepolarizations

We couple these data alongside hemodynamic parameters to afford a robust in vitro prediction of proarrhythmia – in a functioning heart.

Here are some data with E-4031 – a known proarrhythmic compound – vs. control.

Slide1

View Data

Using this paradigm, proarrrhythmia can be conclusively detected – or ruled out – in a concentration-response manner. We screen active test articles daily in the preparation, and have recommended advancing or deprioritizing interesting compounds based on these results.

As the pros and cons of the CiPA initiative clarify, an integrated approach to this area of drug safety has always been the prudent course.

Filed under: Drug Safety Services, Langendorff Heart | No Comments

Multiple Models for Researching the Complexities of PAH

Posted by CorDynamics on November 06th, 2014

To state it simply, pulmonary arterial hypertension is a complex disease.

Our labs have generated substantive data, and after numerous conversations with colleagues, it is clear that researching this disease from multiple aspects is likely the most efficient way to help find new treatments.

We recently presented a comprehensive overview of our PAH findings at a Lunch and Learn at the 2014 Safety Pharmacology Society Annual meeting and again for a client project team.

new_therapies_for_PAH

VIEW PRESENTATION

Over the past several years, companies were focused on providing benefit to PAH patients primarily through a hemodynamic mechanism such as selective pulmonary arterial vasodilation. Recently, the paradigm has shifted to focus more on the remodeling and inflammatory processes associated with the development of PAH.

Although the hypoxia / VEGF antagonist treated rat continues to be the gold standard animal model of this disease, increasingly we have been conducting experiments using a T-cell deficient rat co-treated with VEGF antagonist. This model is dependent on dysregulated immunity contributing to increased inflammation that exacerbates PAH.

Our results showing a protective effect with the LTA4 hydrolase inhibitor bestatin are consistent with the literature. In addition, we now have data demonstrating that sildenafil (PDE5 inhibitor – hemodynamic effect) shows efficacy in this ‘inflammatory’ model as well. A recent article has also shown that sildenafil has an anti-inflammatory effect in monocrotaline treated rats.

Research into developing additional and better treatments for PAH continues at a rapid and growing rate. We are also discovering new mechanisms by which current options exert efficacy. By continuing to refine the animal models of this disease, we stack the odds of success in our favor.

Filed under: Drug Discovery Services, Drug Safety Services, Pulmonary Arterial Hypertension | No Comments