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Archive for the ‘congestive heart failure’ Category


Two Classes of Antithrombotic Drugs: Anticoagulants and Antiplatelet drugs

Reporter: Aviva Lev-Ari, PhD, RN
These drugs are used to treat
  • strokes,
  • myocardial infarctions,
  • pulmonary embolisms,
  • disseminated intravascular coagulation (DIC) and
  • deep vein thrombosis (DVT)
— all potentially life-threatening conditions.
THERAPEUTIC STRATEGIES
• Degrade fibrinogen/fibrin (fibrinolytic agents)
GOAL: eliminate formed clots
• Inhibit clotting mechanism (anticoagulants)
GOAL: prevent progression of thrombosis
• Interfere either with platelet adhesion and/or aggregation (antiplatelet drugs)
GOAL: prevent initial clot formation
Antithrombotic therapy has had an enormous impact in several significant ways.
  • Heparin has made bypass surgery and dialysis possible by blocking clotting in external tubing.
  • Antithrombotic therapy has reduced the risk of blood clots in leg veins (also known as deep-vein thrombosis or DVT), a condition that can lead to death from pulmonary embolism (a clot that blocks an artery to the lungs) by more than 70 percent. And most importantly,
  • it has markedly reduced death from heart attacks, the risk of stroke in people with heart irregularities (atrial fibrillation), and the risk of major stroke in patients with mini-strokes.

Antithrombotic Therapy

This article was published in December 2008 as part of the special ASH anniversary brochure, 50 Years in Hematology: Research That Revolutionized Patient Care.

Normally, blood flows through our arteries and veins smoothly and efficiently, but if a clot, or thrombus, blocks the smooth flow of blood, the result – called thrombosis – can be serious and even cause death. Diseases arising from clots in blood vessels include heart attack and stroke, among others. These disorders collectively are the most common cause of death and disability in the developed world. We now have an array of drugs that can be used to prevent and treat thrombosis – and there are more on the way – but this was not always the case.

Classes of Antithrombotic Drugs

Image Source: http://www.hematology.org/About/History/50-Years/1523.aspx

The most important components of a thrombus are fibrin and platelets. Fibrin is a protein that forms a mesh that traps red blood cells, while platelets, a type of blood cell, form clumps that add to the mass of the thrombus. Both fibrin and platelets stabilize the thrombus and prevent it from falling apart. Fibrin is the more important component of clots that form in veins, and platelets are the more important component of clots that form in arteries where they can cause heart attacks and strokes by blocking the flow of blood in the heart and brain, respectively, although fibrin plays an important role in arterial thrombosis as well.

There are two classes of antithrombotic drugs: anticoagulants and antiplatelet drugs. Anticoagulants slow down clotting, thereby reducing fibrin formation and preventing clots from forming and growing. Antiplatelet agents prevent platelets from clumping and also prevent clots from forming and growing.

Anticoagulant Drugs

The anticoagulants heparin and dicumarol were discovered by chance, long before we understood how they worked. Heparin was first discovered in 1916 by a medical student at The Johns Hopkins University who was investigating a clotting product from extracts of dog liver and heart. In 1939, dicumarol (the precursor to warfarin) was extracted by a biochemist at the University of Wisconsin from moldy clover brought to him by a farmer whose prize bull had bled to death after eating the clover.

Both of these anticoagulants have been used effectively to prevent clots since 1940. These drugs produce a highly variable anticoagulant effect in patients, requiring their effect to be measured by special blood tests and their dose adjusted according to the results. Heparin acts immediately and is given intravenously (through the veins). Warfarin is swallowed in tablet form, but its anticoagulant effect is delayed for days. Therefore, until recently, patients requiring anticoagulants who were admitted to a hospital were started on a heparin infusion and were then discharged from the hospital after five to seven days on warfarin.

In the 1970s, three different groups of researchers in Stockholm, London, and Hamilton, Ontario, began work on low-molecular-weight heparin (LMWH). LMWH is produced by chemically splitting heparin into one-third of its original size. It has fewer side effects than heparin and produces a more predictable anticoagulant response. By the mid 1980s, LMWH preparations were being tested in clinical trials, and they have now replaced heparin for most indications. Because LMWH is injected subcutaneously (under the skin) in a fixed dose without the need for anticoagulant monitoring, patients can now be treated at home instead of at the hospital.

With the biotechnology revolution has come genetically engineered “designer” anticoagulant molecules that target specific clotting enzymes. Anti-clotting substances and their DNA were also extracted from an array of exotic creatures (ticks, leeches, snakes, and vampire bats) and converted into drugs by chemical synthesis or genetic engineering. Structural chemists next began to fabricate small molecules designed to fit into the active component of clotting enzymes, like a key into a lock.

The first successful synthetic anticoagulants were fondaparinux and bivalirudin. Bivalirudin, a synthetic molecule based on the structure of hirudin (the anti-clotting substance found in leeches), is an effective treatment for patients with heart attacks. Fondaparinux is a small molecule whose structure is based on the active component of the much larger LMWH and heparin molecules. It has advantages over LMWH and heparin and has recently been approved by the FDA. Newer designer drugs that target single clotting factors and that can be taken by mouth are undergoing clinical testing. If successful, we will have safer and more convenient replacements for warfarin, the only oral anticoagulant available for more than 60 years.

Antiplatelet Drugs

Blood platelets are inactive until damage to blood vessels or blood coagulation causes them to explode into sticky irregular cells that clump together and form a thrombus. The first antiplatelet drug was aspirin, which has been used to relieve pain for more than 100 years. In the mid-1960s, scientists showed that aspirin prevented platelets from clumping, and subsequent clinical trials showed that it reduces the risk of stroke and heart attack. In 1980, researchers showed that aspirin in very low doses (much lower than that required to relieve a headache) blocked the production of a chemical in platelets that is required for platelet clumping. During that time, better understanding of the process of platelet clumping allowed the development of designer antiplatelet drugs directed at specific targets. We now have more potent drugs, such as clopidogrel, dipyridamole, and abciximab. These drugs are used with aspirin and effectively prevent heart attack and stroke; they also prolong the lives of patients who have already had a heart attack.

SOURCE 
Anticoagulation Drugs:
  • heparin (FONDAPARINUX HEPARIN (Calciparine, Hepathrom, Lipo-Hepin, Liquaemin, Panheprin)
  • warfarin – 4-HYDROXYCOUMARIN (Coumadin) WARFARIN (Athrombin-K, Panwarfin)
  • rivaroxaban (Xarelto)
  • dabigatran (Pradaxa)
  • apixaban (Eliquis)
  • edoxaban (Savaysa)
  • enoxaparin (Lovenox)
  • fondaparinux (Arixtra)
  • ARGATROBAN BIVALIRUDIN (Angiomax)
  • DALTEPARIN (Fragmin)
  • DROTRECOGIN ALFA (ACTIVATED PROTEIN C) (Xigris)
  • HIRUDIN (Desirudin)
  • LEPIRUDIN (Refludan)
  • XIMELAGATRAN (Exanta)

ANTIDOTES

  • PHYTONADIONE (Vitamin K1)
  • PROTAMINE SULFATE AMINOCAPROIC ACID (EACA) (generic, Amicar) (in bleeding disorders)
Antiplatelet Drugs
  • ACETYL SALICYLIC ACID (aspirin) 
  • clopidogrel (Plavix)
  • dipyridamole (Persantine)
  • abciximab (Centocor)
  • EPTIFIBATIDE (Integrilin)
  • TICLOPIDINE (Ticlid)
  • TIROFIBAN (Aggrastat)

THROMBOLYTICS

  1. ANISTREPLASE (APSAC; Eminase)
  2. STREPTOKINASE (Streptase, Kabikinase)
  3. TISSUE PLASMINOGEN ACTIVATORS (tPAs):
  • ALTEPLASE (Activase),
  • RETEPLASE (Retavase),
  • TENECTEPLASE (TNKase)
  • UROKINASE (Abbokinase)

Fibrinolytic Drugs

Fibrinolytic therapy is used in selected patients with venous thromboembolism. For example, patients with massive or submassive PE can benefit from systemic or catheter-directed fibrinolytic therapy. The latter can also be used as an adjunct to anticoagulants for treatment of patients with extensive iliofemoral-vein thrombosis.

Arterial and venous thrombi are composed of platelets and fibrin, but the proportions differ.

  • Arterial thrombi are rich in platelets because of the high shear in the injured arteries. In contrast,
  • venous thrombi, which form under low shear conditions, contain relatively few platelets and are predominantly composed of fibrin and trapped red cells.
  • Because of the predominance of platelets, arterial thrombi appear white, whereas venous thrombi are red in color, reflecting the trapped red cells.

SOURCE

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Experimental Therapy (Left inter-atrial shunt implant device) for Heart Failure: Expert Opinion on a Preliminary Study on Heart Failure with preserved Ejection Fraction 

 

Article Curator: Aviva Lev-Ari, PhD, RN

 

Expert Opinion by Cardiologist Justin D. Pearlman MD PhD FACC

 

Pearls From: Ted Feldman, MD – A glimmer of hope for HFpEF treatment?

Evanston Hospital in Illinois

by Nicole Lou, Contributing Writer, MedPage Today

SOURCE ARTICLE

https://www.medpagetoday.com/cardiology/chf/72759?xid=nl_mpt_DHE_2018-05-09

WATCH VIDEO

https://www.medpagetoday.com/cardiology/chf/72759?xid=nl_mpt_DHE_2018-05-09

 

Heart Failure with preserved Ejection Fraction (or HFpEF) – Experimental Therapy: Inter-atrial shunt implantable device for relieving pressure overload and improve the prognosis of patients with a 50% ejection fraction

vs

Heart Failure with reduced Ejection Fraction (HFrEF)

 

  • HFpEF is similar in frequency and sadly, similar in prognosis to heart failure with reduced ejection fraction, and everybody thinks about the EF 20% or 30% patient as having a poor prognosis and doesn’t realize that the EF 40% or 45% or 50% patient with clinical heart failure has the same prognosis.
  • Patients with mitral stenosis and elevated left atrial pressure, which is the genesis of HFpEF, if they had an ASD historically, this decompressed the left atrium and they presented much, much later in the course of the disease with any signs of heart failure.
  • Inspiration for design of the Left inter-atrial shunt implant device

Minimally invasive transcatheter closure is the primary treatment option for secundum atrial septal defects (ASD). The AMPLATZER™ Septal Occluder is the proven standard of care in transcatheter ASD closure

  • Left inter-atrial shunt implant device, Dr. Ted Feldman calls IASD.

It’s like an ASD occluder, a little nitinol disc, but it has a hole in the middle. We did some baseline hemodynamic modeling using a simulator and calculated that we would get a small shunt with an eight millimeter opening, that that would be enough to reduce left atrial pressure overload during exercise without overloading the right side of the heart, without creating too big a shunt.

Preliminary results: We found that peak exercise wedge pressure was significantly decreased in the patients with the device compared to those without a shunt. We found that the shunt ratio, the amount of flow across the shunt was a Qp:Qs, pulmonary to systemic flow ratio, of 1.2 preserved at 30 days and 6 months and that most of these patients feel better.

Ted Feldman, MD, Evanston Hospital in Illinois

The mechanism, I think we’ve established, that we do decompress the left atrium with exertion and now we need to demonstrate that the clinical outcomes in a larger population are robust enough to carry this into practice.

Expert Opinion by Cardiologist Justin D. Pearlman MD PhD FACC

  • It is a bit biased saying no treatment for CHD bias pEF, when there is support for so called triple therapy of beta blocker, acei/arb/arni, and aldosterone inhibitor, plus tight bp control and additional afterload reduction if valve leaks contribute.
  • It is an interesting proposition to induce an 8 mm IAS shunt, but it poses a risk for paradoxical emboli, which have been associated with
  1. visual field cuts,
  2. TIA and
  3. migraine.

Paradoxical Embolism

Updated: Jun 10, 2016
  • Author: Igor A Laskowski, MD; Chief Editor: Vincent Lopez Rowe, MD  more…
 Background

The clinical manifestations of paradoxical embolism (PDE) are nonspecific, [1and the diagnosis is difficult to establish. Patients with PDE may present with neurologic abnormalities or features suggesting arterial embolism. The disease starts with the formation of emboli within the venous system, which traverse a patent foramen ovale (PFO) and enter the systemic circulation. [234PFOs have been found on autopsy in up to 35% of the healthy population.

PDE originates in the veins of the lower extremities and occasionally in the pelvic veins. Emboli may be of various types, such as clots, air, tumor, fat, and amniotic fluid. [5Septic emboli have led to brain abscesses. Projectile embolization is rare (eg, from a shotgun pellet).

Management of PDE is both medical and surgical in nature. PDE is considered the major cause of cerebral ischemic events in young patients. On rare occasions, it may occlude the pelvic aortic bifurcation. The largest documented thrombus in a PFO (impending PDE) was 25 cm in length.

PDE is confirmed by the presence of thrombus within an intracardiac defect on contrast echocardiography or at autopsy. It may be presumed in the presence of arterial embolism with no evidence of left-side circulation thrombus, deep venous thrombosis (DVT) with or without pulmonary embolism (PE), and right-to-left shunting through an intracardiac communication, commonly the PFO. [6]

SOURCE for Paradoxical Embolism

https://emedicine.medscape.com/article/460607-overview

 

SOURCE for Dr. Pearlman’s Expert Opinion

From: Justin MDMEPhD <jdpmdphd@gmail.com>

Date: Wednesday, May 9, 2018 at 2:25 PM

To: Aviva Lev-Ari <AvivaLev-Ari@alum.berkeley.edu>

Cc: “Dr. Larry Bernstein” <larry.bernstein@gmail.com>

Subject: Re: WHICH of our Heart Failure ARTICLES I should UPDATE with the following Pearls From: Ted Feldman, MD | Medpage Today

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Cheetah Medical Introduces New Algorithm for Fluid Management

Reporter: Lawrence J Mulligan, PhD

 

Cheetah Medical Advances the Science of Fluid Management

Cheetah Medical is the pioneer and leading global provider of 100% noninvasive hemodynamic monitoring technologies that are designed for use in critical care, OR and emergency department settings. The CHEETAH NICOM™ and STARLING™ SV technologies use a proprietary algorithm to calculate parameters related to the volume of blood and the functioning of patients’ circulatory systems. Medical professionals use this information to assess patients’ unique volume requirements, guide volume management decisions and maintain adequate organ perfusion. Cheetah Medical technologies are designed to enable more confident, informed therapy decisions that support clinical goals of improving patient outcomes and driving economic efficiencies.

NEWTON, Mass. –(BUSINESS WIRE)– Cheetah Medical announced today that its eighth abstract on fluid management will be presented at Society of Critical Care Medicine meeting in January. Building on previous work, this abstract demonstrates a strong association between large volume fluid administration in septic shock and increased risk of death in more than 23,000 patients.

Each year, millions of patients require hemodynamic monitoring to ensure optimal volume and perfusion management. While intravenous fluid is typical first-line therapy for many critical care situations, volume management has been a challenge for the healthcare community. It is often difficult for a clinician to know the right amount of fluid to administer to patients, and there are serious complications associated with both under and over resuscitation.

“Ever since we’ve been using intravenous fluid, clinicians have been asking, ‘What is the right amount?’” said Doug Hansell, MD and Cheetah’s Chief Physician Executive. “Today, with non-invasive Cheetah technology, we have new tools to answer this question, and we are learning that getting this question right is more important than ever.”

Cheetah Medical has been working with leading researchers using a large U.S. dataset to better understand the risks and benefits of fluid administration. During the past two years, researchers have now released eight clinical abstracts on the importance of fluid management.

  • FLUID ADMINISTRATION IN SEPSIS AND SEPTIC SHOCK – PATTERNS AND OUTCOMES: Sepsis and septic shock is a huge national priority, as it is the most expensive condition to treat, at $24 billion per year (AHRQ). This study identified a strong association between large fluid administration (more than five liters) and excess mortality in septic shock patients. As expected, sicker patients received more fluid. However, even after accounting for the severity of illness, these patients had an increased risk of dying. (Society of Critical Care Medicine Annual Conference, January 2017)
  • FLUID ADMINISTRATION IN OPEN AND LAPAROSCOPIC ABDOMINAL SURGERY: The study looked at the relationship between intraoperative fluid therapy and complications following abdominal surgery.Based on data from 18,633 patients, an increase in complications was found with day-of-surgery fluid use above five liters for open abdominal procedures. The study recommended individualized fluid therapy to reduce potentially negative effects from over/under resuscitation with intravenous fluids. (American Society of Anesthesiologists [ASA] 2016 Annual Meeting)
  • FLUID PRESCRIPTIONS IN HOSPITALIZED PATIENTS WITH RENAL FAILURE: The implication of volume resuscitation and potential complications among patients with acute kidney injuries (AKIs) has been widely debated. This study examined the relationship between fluid administration and outcomesamong 62,695 AKI patients. It found the potential for both under and over resuscitation in those who received treatments with vasopressors. A better understanding of individual fluid needs was seen for patients requiring pressor and mechanical ventilation support. (European Society of Intensive Care Medicine [ESICM] Annual Congress, 2016)
  • EFFECTS OF FLUIDS ADMINISTRATION IN PATIENTS WITH SEPTIC SHOCK WITH OR WITHOUT HEART FAILURE (HF): The study examined the relationship between indications of fluid overload in sepsis patients (with or without diastolic HF) and outcomes. For 29,098 patients, mortality was the highest among those who received the highest volumes of fluid. It also noted that patients with diagnosed diastolic HF received less fluids and exhibited a significantly lower mortality than predicted. These lower mortality rates could be a result of a more conservative fluid treatment strategy applied in patients known to be at risk for fluid overload. (American Thoracic Society [ATS] 2016 International Conference)
  • WIDE PRACTICE VARIABILITY IN FLUID RESUSCITATION OF CRITICALLY ILL PATIENTS WITH ARDS: The study looked at how variable fluid resuscitation testing and treatments impacted the outcomes of patients with acute respiratory distress syndrome (ARDS). An analysis of 1,052 patients highlighted a highly variable fluid resuscitation. The findings suggest a widespread variability in provider decision-making regarding fluid resuscitation, which may be detrimental to quality and costs, lowering the overall value of care. (American Thoracic Society [ATS] 2016 International Conference)
  • POTENTIAL HARM ASSOCIATED WITH SEVERITY-ADJUSTED TREATMENT VARIABILITY IN FLUID RESUSCITATION OF CRITICALLY ILL SEPTIC PATIENTS: The study set out to determine treatment variability for patients with severe sepsis and how it may impact mortality. Retrospectively analyzing 77,032 patients, a high degree of treatment variability was found for fluid resuscitation, with a range of 250 ml to more than 7L of fluid administered. For patients who received less fluid, there was no increased risk of mortality. In those who received the most fluid, there was a strong association with worse hospital mortality. (American Thoracic Society [ATS] 2016 International Conference)
  • ASSOCIATION OF FLUIDS AND OUTCOMES IN EMERGENCY DEPARTMENT PATIENTS HOSPITALIZED WITH COMMUNITY-ACQUIRED PNEUMONIA (CAP): Analyzing 192,806 CAP patients, the study looked at the correlation between fluid-volume overload, hospital mortality and ventilator-free days (VFDs). A significant association was found between the amount of fluid administered on day one, increased mortality and decreased VFDs. The study may have also identified a subset of CAP patients who could benefit from a more restrictive fluid strategy. (36thInternational Symposium on Intensive Care and Emergency Medicine)
  • FLUID ADMINISTRATION IN COMMUNITY-ACQUIRED SEPSISEXAMINATION OF A LARGE ADMINISTRATIVE DATABASE: The study looked at variation in fluid administration practices and compliance with “Surviving Sepsis” guidelines, which recommend a minimum initial fluid administration of 30cc/kg in sepsis-induced tissue hypoperfusion patients. It found that a substantial proportion of patients (47.4 %) with community-acquired sepsis received less than the recommended guidelines within the first 24 hours. (Society of Critical Care Medicine Annual Conference, 2016)

“We are very proud to have supported this work – we are advancing the science of fluid management and helping to improve our understanding of how better fluid management may improve patient outcomes,” said Chris Hutchison, CEO of Cheetah Medical.

 

SOURCE

https://www.cheetah-medical.com/cheetah-medical-advances-science-fluid-management/

 

Other related articles published in this Open Access On-line Scientific Journal includes the following:

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Inferior Vena Cava Filters: Device for Prevention of Pulmonary Embolism and Thrombosis

Reporter: Aviva Lev-Ari, PhD, RN

 

UPDATED on 7/18/2018

 

Original Investigation
Cardiology
July 13, 2018

Association of Inferior Vena Cava Filter Placement for Venous Thromboembolic Disease and a Contraindication to Anticoagulation With 30-Day Mortality

JAMA Network Open. 2018;1(3):e180452. doi:10.1001/jamanetworkopen.2018.0452
Key Points

Question  What is the association of inferior vena cava filter placement with 30-day mortality in patients with venous thromboembolic disease and a contraindication to anticoagulation?

Findings  In this cohort study, using 2 different statistical methods with adjustment for immortal time bias, inferior vena cava filter placement in patients with venous thromboembolic disease and a contraindication to anticoagulation was associated with an increased risk of 30-day mortality.

Meaning  Randomized clinical trials are needed to define the role of inferior vena cava filter placement in patients with venous thromboembolic disease and a contraindication to anticoagulation.

 

Abstract

Importance  Despite the absence of data from randomized clinical trials, professional societies recommend inferior vena cava (IVC) filters for patients with venous thromboembolic disease (VTE) and a contraindication to anticoagulation therapy. Prior observational studies of IVC filters have suggested a mortality benefit associated with IVC filter insertion but have often failed to adjust for immortal time bias, which is the time before IVC filter insertion, during which death can only occur in the control group.

Objective  To determine the association of IVC filter placement with 30-day mortality after adjustment for immortal time bias.

Design, Setting, and Participants  This comparative effectiveness, retrospective cohort study used a population-based sample of hospitalized patients with VTE and a contraindication to anticoagulation using the State Inpatient Database and the State Emergency Department Database, part of the Healthcare Cost and Utilization Project of the Agency for Healthcare Research and Quality, from hospitals in California (January 1, 2005, to December 31, 2011), Florida (January 1, 2005, to December 31, 2013), and New York (January 1, 2005, to December 31, 2012). Data analysis was conducted from September 15, 2015, to March 14, 2018.

Exposure  Inferior vena cava filter placement.

Main Outcomes and Measures  Multivariable Cox proportional hazard models were constructed with IVC filters as a time-dependent variable that adjusts for immortal time bias. The Cox model was further adjusted using the propensity score as an adjustment variable.

Results  Of 126 030 patients with VTE, 61 281 (48.6%) were male and the mean (SD) age was 66.9 (16.6) years. In this cohort, 45 771 (36.3%) were treated with an IVC filter, whereas 80 259 (63.7%) did not receive a filter. In the Cox model with IVC filter status analyzed as a time-dependent variable to account for immortal time bias, IVC filter placement was associated with a significantly increased hazard ratio of 30-day mortality (1.18; 95% CI, 1.13-1.22; P < .001). When the propensity score was included in the Cox model, IVC filter placement remained associated with an increased hazard ratio of 30-day mortality (1.18; 95% CI, 1.13-1.22; P < .001).

Conclusions and Relevance  After adjustment for immortal time bias, IVC filter placement was associated with increased 30-day mortality in patients with VTE and a contraindication to anticoagulation. Randomized clinical trials are needed to determine the efficacy of IVC filter placement in patients with VTE and a contraindication to anticoagulation.

 

Requiem for Liberalizing Indications for Vena Caval Filters?

Samuel Z. Goldhaber

Guidelines

However, it is premature to hammer nails into the coffin and to gather as a medical community for a requiem that celebrates no indication for liberalizing indications for placing an IVC filter. Instead, we need to shift the focus of the questions that we investigate and pour resources into further randomized and observational trials of IVC filter insertion in special highrisk populations.

There remain important groups of patients who may benefit from IVC filters with reduction in PE and PE-associated mortality (Table 2). In some cases, tantalizing data suggest that these populations warrant filters. In other cases, we lack data to guide us. Patients with massive PE—accompanied by cardiogenic shock requiring vasopressors to support blood pressure—are desperately ill. They are clinically unstable. An additional PE under these circumstances can be the fatal blow. Data from the National Inpatient Sample and the International Cooperative PE Registry suggest that filters in these patients may be lifesaving.

Patients with severe PE who undergo acute surgical pulmonary embolectomy are vulnerable to recurrent PE, especially during the early postoperative period where full anticoagulation cannot be immediately implemented. I have had personal experience managing this type of patient where the embolectomy is successful but the patient dies of recurrent PE.19

Table 1. Generally Accepted Consensus Recommendations for IVC Filter Insertion in Patients With VTE

  • Major bleeding on full-dose anticoagulation
  • Major contraindication to full-dose anticoagulation
  • New-onset acute PE (especially recurrent PE) despite well-documented fulldose anticoagulation for an existing VTE

IVC indicates inferior vena caval; PE, pulmonary embolism; and VTE, venous thromboembolism.

 

Table 2. Special Populations Where Benefits of IVC Filter Insertion May Outweigh Risks

  • Massive PE or high-risk submassive PE
  • Surgical pulmonary embolectomy
  • Cancer patients with VTE or at high risk of VTE with concomitant high risk of bleeding if anticoagulated
  • Surgical patients (especially during preoperative evaluation) at high risk of VTE with concomitant high risk of bleeding if anticoagulated

IVC indicates inferior vena caval; PE, pulmonary embolism; and VTE, venous thromboembolism.

http://dx.doi.org/10.1161/CIRCULATIONAHA.116.022730

References

1. Stein PD, Matta F, Hull RD. Increasing use of vena cava filters for prevention of pulmonary embolism. Am J Med. 2011;124:655–661. doi:10.1016/j.amjmed.2011.02.021.

2. Jia Z, Wu A, Tam M, Spain J, McKinney JM, Wang W. Caval penetration by inferior vena cava filters: a systematic literature review of clinical significance and management. Circulation. 2015;132:944–952. doi: 10.1161/ CIRCULATIONAHA.115.016468

3. Owens CA, Bui JT, Knuttinen MG, Gaba RC, Carrillo TC, Hoefling N, Layden-Almer JE. Intracardiac migration of inferior vena cava filters: review of published data. Chest. 2009;136:877–887. doi: 10.1378/ chest.09-0153.

4. Nicholson W, Nicholson WJ, Tolerico P, Taylor B, Solomon S, Schryver T, McCullum K, Goldberg H, Mills J, Schuler B, Shears L, Siddoway L, Agarwal N, Tuohy C. Prevalence of fracture and fragment embolization of Bard retrievable vena cava filters and clinical implications including cardiac perforation and tamponade. Arch Intern Med. 2010;170:1827–1831. doi: 10.1001/archinternmed.2010.316.

5. Angel LF, Tapson V, Galgon RE, Restrepo MI, Kaufman J. Systematic review of the use of retrievable inferior vena cava filters. J Vasc Interv Radiol. 2011;22:1522–1530.e3. doi: 10.1016/j.jvir.2011.08.024.

19. Aklog L, Williams CS, Byrne JG, Goldhaber SZ. Acute pulmonary embolectomy: a contemporary approach. Circulation. 2002;105:1416–1419.

Other related articles published in this Open Access Online Scientific Journal include the follwoing:

 

Xarelto (Rivaroxaban): Anticoagulant Therapy gains FDA New Indications and Risk Reduction for: (DVT) and (PE), while in use for Atrial fibrillation increase in Gastrointestinal (GI) Bleeding Reported

https://pharmaceuticalintelligence.com/2012/11/04/xarelto-rivaroxaban-anticoagulant-therapy-gains-fda-new-indications-and-risk-reduction-for-dvt-and-pe-while-in-use-for-atrial-fibrillation-increase-in-gastrointestinal-gi-bleeding-reported/

Venous Thromboembolism (VTE): Blood Clots in Leg and Lungs – No. 3 Cardiovascular Killer Globally – Is Leading Cause of Premature Death and Disability in Hospitals

https://pharmaceuticalintelligence.com/2014/10/13/venous-thromboembolism-vte-blood-clots-in-leg-and-lungs-no-3-cardiovascular-killer-globally-is-leading-cause-of-premature-death-and-disability-in-hospitals/

The Relation between Coagulation and Cancer affects Supportive Treatments

https://pharmaceuticalintelligence.com/2015/10/19/the-relation-between-coagulation-and-cancer-affects-supportive-treatments/

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Entire Family of Impella Abiomed Impella® Therapy Left Side Heart Pumps: FDA Approved To Enable Heart Recovery

Reporter: Aviva Lev-Ari, PhD, RN

 

Abiomed Impella® Therapy Receives FDA Approval for Cardiogenic Shock After Heart Attack or Heart Surgery

Entire Family of Impella Left Side Heart Pumps FDA Approved To Enable Heart Recovery

DANVERS, Mass., April 07, 2016 (GLOBE NEWSWIRE) — Abiomed, Inc. (NASDAQ:ABMD), a leading provider of breakthrough heart support technologies, today announced that it has received U.S. Food and Drug Administration (FDA) Pre-Market Approval (PMA) for its Impella 2.5™, Impella CP®, Impella 5.0™ and Impella LD™ heart pumps to provide treatment of ongoing cardiogenic shock. In this setting, the Impella heart pumps stabilize the patient’s hemodynamics, unload the left ventricle, perfuse the end organs and allow for recovery of the native heart.  This latest approval adds to the prior FDA indication of Impella 2.5 for high risk percutaneous coronary intervention (PCI), or Protected PCI™, received in March 2015.

With this approval, these are the first and only percutaneous temporary ventricular support devices that are FDA-approved as safe and effective for the cardiogenic shock indication, as stated below:

The Impella 2.5, Impella CP, Impella 5.0 and Impella LD catheters, in conjunction with the Automated Impella Controller console, are intended for short-term use (<4 days for the Impella 2.5 and Impella CP and <6 days for the Impella 5.0 and Impella LD) and indicated for the treatment of ongoing cardiogenic shock that occurs immediately (<48 hours) following acute myocardial infarction (AMI) or open heart surgery as a result of isolated left ventricular failure that is not responsive to optimal medical management and conventional treatment measures with or without an intra-aortic balloon pump.  The intent of the Impella system therapy is to reduce ventricular work and to provide the circulatory support necessary to allow heart recovery and early assessment of residual myocardial function.

The product labeling also allows for the clinical decision to leave Impella 2.5, Impella CP, Impella 5.0 and Impella LD in place beyond the intended duration of four to six days due to unforeseen circumstances.

The Impella products offer the unique ability to both stabilize the patient’s hemodynamics before or during a PCI procedure and unload the heart, which allows the muscle to rest and potentially recover its native function. Heart recovery is the ideal option for a patient’s quality of life and as documented in several clinical papers, has the ability to save costs for the healthcare system1,2,3.

Cardiogenic shock is a life-threatening condition in which the heart is suddenly unable to pump enough blood and oxygen to support the body’s vital organs. For this approval, it typically occurs during or after a heart attack or acute myocardial infarction (AMI) or cardiopulmonary bypass surgery as a result of a weakened or damaged heart muscle. Despite advancements in medical technology, critical care guidelines and interventional techniques, AMI cardiogenic shock and post-cardiotomy cardiogenic shock (PCCS) carry a high mortality risk and has shown an incremental but consistent increase in occurrence in recent years in the United States.

“This approval sets a new standard for the entire cardiovascular community as clinicians continue to seek education and new approaches to effectively treat severely ill cardiac patients with limited options and high mortality risk,” said William O’Neill, M.D., medical director of the Center for Structural Heart Disease at Henry Ford Hospital. “The Impella heart pumps offer the ability to provide percutaneous hemodynamic stability to high-risk patients in need of rapid and effective treatment by unloading the heart, perfusing the end organs and ultimately, allowing for the opportunity to recover native heart function.”

“Abiomed would like to recognize our customers, physicians, nurses, scientists, regulators and employees for their last fifteen years of circulatory support research and clinical applications. This FDA approval marks a significant milestone in the treatment of heart disease. The new medical field of heart muscle recovery has begun,” said Michael R. Minogue, President, Chairman and Chief Executive Officer of Abiomed. “Today, Abiomed only treats around 5% of this AMI cardiogenic shock patient population, which suffers one of the highest mortality risks of any patient in the heart hospital. Tomorrow, Abiomed will be able to educate and directly partner with our customers and establish appropriate protocols to improve the patient outcomes focused on native heart recovery.”

Abiomed Data Supporting FDA Approval

The data submitted to the FDA in support of the PMA included an analysis of 415 patients from the RECOVER 1 study and the U.S. Impella registry (cVAD Registry™), as well as an Impella literature review including 692 patients treated with Impella from 17 clinical studies. A safety analysis reviewed over 24,000 Impella treated patients using the FDA medical device reporting (“MDR”) database, which draws from seven years of U.S. experience with Impella.

In addition, the Company also provided a benchmark analysis of Impella patients in the real-world Impella cVAD registry vs. these same patient groups in the Abiomed AB5000/BVS 5000 Registry. The Abiomed BVS 5000 product was the first ventricular assist device (VAD) ever approved by the FDA in 1991 based on 83 patient PMA study. In 2003, the AB5000 Ventricle received FDA approval and this also included a PMA study with 60 patients.

For this approval, the data source for this benchmark analysis was a registry (“AB/BVS Registry”) that contained 2,152 patients that received the AB5000 and BVS 5000 devices, which were originally approved for heart recovery. The analysis examined by the FDA used 204 patients that received the AB5000 device for the same indications. This analysis demonstrated significantly better outcomes with Impella in these patients.

The Company believes this is the most comprehensive review ever submitted to the FDA for circulatory support in the cardiogenic shock population.

  1. Maini B, Gregory D, Scotti DJ, Buyantseva L. Percutaneous cardiac assist devices compared with surgical hemodynamic support alternatives: Cost-Effectiveness in the Emergent Setting.Catheter Cardiovasc Interv. 2014 May 1;83(6):E183-92.
  2. Cheung A, Danter M, Gregory D. TCT-385 Comparative Economic Outcomes in Cardiogenic Shock Patients Managed with the Minimally Invasive Impella or Extracorporeal Life Support. J Am Coll Cardiol. 2012;60(17_S):. doi:10.1016/j.jacc.2012.08.413.
  3. Gregory D, Scotti DJ, de Lissovoy G, Palacios I, Dixon, Maini B, O’Neill W. A value-based analysis of hemodynamic support strategies for high-risk heart failure patients undergoing a percutaneous coronary intervention. Am Health Drug Benefits. 2013 Mar;6(2):88-99


ABOUT IMPELLA

Impella 2.5 received FDA PMA approval for high risk PCI in March 2015, is supported by clinical guidelines, and is reimbursed by the Centers for Medicare & Medicaid Services (CMS) under ICD-9-CM code 37.68 for multiple indications. The Impella RP® device received Humanitarian Device Exemption (HDE) approval in January 2015. The Impella product portfolio, which is comprised of Impella 2.5, Impella CP, Impella 5.0, Impella LD, and Impella RP, has supported over 35,000 patients in the United States.

The ABIOMED logo, ABIOMED, Impella, Impella CP, and Impella RP are registered trademarks of Abiomed, Inc. in the U.S.A. and certain foreign countries.  Impella 2.5, Impella 5.0, Impella LD, and Protected PCI are trademarks of Abiomed, Inc.

ABOUT ABIOMED
Based in Danvers, Massachusetts, Abiomed, Inc. is a leading provider of medical devices that provide circulatory support.  Our products are designed to enable the heart to rest by improving blood flow and/or performing the pumping of the heart.  For additional information, please visit: www.abiomed.com

FORWARD-LOOKING STATEMENTS
This release includes forward-looking statements.  These forward-looking statements generally can be identified by the use of words such as “anticipate,” “expect,” “plan,” “could,” “may,” “will,” “believe,” “estimate,” “forecast,” “goal,” “project,” and other words of similar meaning.  These forward-looking statements address various matters including, the Company’s guidance for fiscal 2016 revenue. Each forward-looking statement contained in this press release is subject to risks and uncertainties that could cause actual results to differ materially from those expressed or implied by such statement.  Applicable risks and uncertainties include, among others, uncertainties associated with development, testing and related regulatory approvals, including the potential for future losses, complex manufacturing, high quality requirements, dependence on limited sources of supply, competition, technological change, government regulation, litigation matters, future capital needs and uncertainty of additional financing, and the risks identified under the heading “Risk Factors” in the Company’s Annual Report on Form 10-K for the year ended March 31, 2015 and the Company’s Quarterly Report on Form 10-Q for the quarter ended September 30, 2015, each filed with the Securities and Exchange Commission, as well as other information the Company files with the SEC.  We caution investors not to place considerable reliance on the forward-looking statements contained in this press release.  You are encouraged to read our filings with the SEC, available at www.sec.gov, for a discussion of these and other risks and uncertainties.  The forward-looking statements in this press release speak only as of the date of this release and the Company undertakes no obligation to update or revise any of these statements.  Our business is subject to substantial risks and uncertainties, including those referenced above.  Investors, potential investors, and others should give careful consideration to these risks and uncertainties.

For more information, please contact: Aimee Genzler Director, Corporate Communications 978-646-1553 agenzler@abiomed.com Ingrid Goldberg Director, Investor Relations igoldberg@abiomed.com

SOURCE
http://investors.abiomed.com/releasedetail.cfm?ReleaseID=964113

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Previously undiscerned value of hs-troponin

Curators: Larry H. Bernstein, MD, FCAP and Aviva Lev-Ari, PhD, RN

 

UPDATED on 8/14/2018

Siemens Launches High-sensitivity Troponin Test for Faster Diagnosis of Heart Attacks

The new troponin I assays can detect lower levels of troponin compared to conventional testing

July 25, 2018 — The U.S. Food and Drug Administration (FDA) cleared Siemens Healthineers high-sensitivity troponin I assays (TnIH) for the Atellica IM and ADVIA Centaur XP/XPT in vitro diagnostic analyzers from Siemens Healthineers to aid in the early diagnosis of myocardial infarctions.

The new tests can shorten the time doctors need to diagnose a life-threatening heart attacks. The time to first results is 10 minutes. When a patient experiencing chest pain enters the emergency department, a physician orders a blood test to determine whether troponin is present. As blood flow to the heart is blocked, the heart muscle begins to die in as few as 30 to 60 minutes and releases troponin into the bloodstream.

The company said its high-sensitivity performance of the two new Siemens TnIH assays offers the ability to detect lower levels of troponin at significantly improved precision at the 99th percentile, and detect smaller changes in a patient’s troponin level as repeat testing occurs. This design affords clinicians greater confidence in the results with precision that provides the ability to measure slight, yet critical, changes to begin treatment.[1,2]

Chest pain is the cause of more than 8 million visits annually nationwide to emergency departments, but only 5.5 percent of those visits lead to serious diagnoses such as heart attacks.[3] Armed with data to properly triage patients sooner or to exclude myocardial infarctions, the Siemens Healthineers TnIH assays can help support testing initiatives tied to improving patient experience.

“Our emergency department is overcrowded with patients. If we can do a more efficient job at triaging patients to receive the proper level of care and to discharge the patients who do not need to stay in the emergency department, this will have a tremendous economic advantage for our healthcare system,” said Alan Wu, M.D., chief of clinical chemistry and toxicology at Zuckerberg San Francisco General Hospital and Trauma Center.

Siemens is launching the product at the 70th AACC Annual Scientific Meeting and Clinical Lab Expo taking place July 31 to Aug. 2 in Chicago.

For more information: http://www.siemens-healthineers.com

Watch the related VIDEO: Use of High Sensitivity Troponin Testing in the Emergency Department — Interview with James Januzzi, M.D., Massachusetts General Hospital

SOURCE

https://www.dicardiology.com/product/siemens-launches-high-sensitivity-troponin-test-faster-diagnosis-heart-attacks?eid=333021707&bid=2192216

References:

1. Eggers K, Jernberg T, Ljung L, Lindahl B. High-Sensitivity Cardiac Troponin-Based Strategies for the Assessment of Chest Pain Patients—A Review of Validation and Clinical Implementation Studies. Clin Chem. 2018;64(7). DOI: 10.1373/clinchem.2018.287342

2. Collinson P. High-sensitivity troponin measurements: challenges and opportunities for the laboratory and the clinician. Annals of Clinical Biochemistry. 2016;53(2) 191–195. DOI: 10.1177/0004563215619946

3. Hsia RY, Hale Z, Tabas JA. A National Study of the Prevalence of Life-Threatening Diagnoses in Patients With Chest Pain. JAMA Intern Med. 2016;176(7):1029–1032. DOI:10.1001/jamainternmed.2016.2498

 

 

Troponin Rise Predicts CHD, HF, Mortality in Healthy People: ARIC Analysis

Veronica Hackethal, MD

Increases in levels of cardiac troponin T by high-sensitivity assay (hs-cTnT) over time are associated with later risk of death, coronary heart disease (CHD), and especially heart failure in apparently healthy middle-aged people, according to a report published June 8, 2016 in JAMA Cardiology[1].

The novel findings, based on a cohort of >8000 participants from the Atherosclerosis Risk in Communities (ARIC) study followed up to 16 years, are the first to show “an association between temporal hs-cTnT change and incident CHD events” in asymptomatic middle-aged adults,” write the authors, led by Dr John W McEvoy (Johns Hopkins University School of Medicine, Baltimore, MD).

Individuals with the greatest troponin increases over time had the highest risk for poor cardiac outcomes. The strongest association was for risk of heart failure, which reached almost 800% for those with the sharpest hs-cTnT rises.

Intriguingly, those in whom troponin levels fell at least 50% had a reduced mortality risk and may have had a slightly decreased risk of later HF or CHD.

“Serial testing over time with high-sensitivity cardiac troponins provided additional prognostic information over and above the usual clinical risk factors, [natriuretic peptide] levels, and a single troponin measurement. Two measurements appear better than one when it comes to informing risk for future coronary heart disease, heart failure, and death,” McEvoy told heartwire from Medscape.

He cautioned, though, that the conclusion is based on observational data and would need to be confirmed in clinical trials. Moreover, high-sensitivity cardiac troponin assays are widely used in Europe but are not approved in the US.

An important next step after this study, according to an accompanying editorial from Dr James Januzzi (Massachusetts General Hospital, Boston, MA), would be to evaluate whether the combination of hs-troponin and natriuretic peptides improves predictive value in this population[2].

“To the extent prevention is ultimately the holy grail for defeating the global pandemic of CHD, stroke, and HF, the main reason to do a biomarker study such as this would be to set the stage for a biomarker-guided strategy to improve the medical care for those patients at highest risk, as has been recently done with [natriuretic peptides],” he wrote.

The ARIC prospective cohort study entered and followed 8838 participants (mean age 56, 59% female, 21.4% black) in North Carolina, Mississippi, Minneapolis, and Maryland from January 1990 to December 2011. At baseline, participants had no clinical signs of CHD or heart failure.

Levels of hs-cTnT, obtained 6 years apart, were categorized as undetectable (<0.005 ng/mL), detectable (≥0.005 ng/mL to <0.014 ng/mL), and elevated (>0.014 ng/mL).

Troponin increases from <0.005 ng/mL to 0.005 ng/mL or higher independently predicted development of CHD (HR 1.41; 95% CI 1.16–1.63), HF (HR 1.96; 95% CI 1.62–2.37), and death (HR 1.50; 95% CI 1.31–1.72), compared with undetectable levels at both measurements.

Hazard ratios were adjusted for age, sex, race, body-mass index, C-reactive protein, smoking status, alcohol-intake history, systolic blood pressure, current antihypertensive therapy, diabetes, serum lipid and cholesterol levels, lipid-modifying therapy, estimated glomerular filtration rate, and left ventricular hypertrophy.

Subjects with >50% increase in hs-cTnT had a significantly increased risk of CHD (HR 1.28; 95% CI 1.09–1.52), HF (HR 1.60; 95% CI 1.35–1.91), and death (HR 1.39; 95% CI 1.22–1.59).

Risks for those end points fell somewhat for those with a >50% decrease in hs-cTnT (CHD: HR 0.47; 95% CI 0.22–1.03; HF: HR 0.49 95% CI 0.23–1.01; death: HR 0.57 95% CI 0.33–0.99).

Among participants with an adjudicated HF hospitalization, the group writes, associations of hs-cTnT changes with outcomes were of similar magnitude for those with HF with preserved ejection fraction (HFpEF) and HF with reduced ejection fraction (HFrEF).

Few biomarkers have been linked to increased risk for HFpEF, and few effective therapies exist for it. That may be due to problems identifying and enrolling patients with HFpEF in clinical trials, Dr McEvoy pointed out.

“We think the increased troponin over time reflects progressive myocardial injury or progressive myocardial damage,” Dr McEvoy said. “This is a window into future risk, particularly with respect to heart failure but other outcomes as well. It may suggest high-sensitivity troponins as a marker of myocardial health and help guide interventions targeting the myocardium.”

Moreover, he said, “We think that high-sensitivity troponin may also be a useful biomarker along with [natriuretic peptides] for emerging trials of HFpEF therapy.”

But whether hs-troponin has the potential for use as a screening tool is a question for future studies, according to McEvoy.

In his editorial, Januzzi pointed out several implications of the study, including the possibility for lowering cardiac risk in those with measurable hs-troponin, and that HF may be the most obvious outcome to target. Also, optimizing treatment and using cardioprotective therapies may reduce risk linked to increases in hs-troponin. Finally, long-term, large clinical trials on this issue will require a multidisciplinary team effort from various sectors.

“What is needed now are efforts toward developing strategies to upwardly bend the survival curves of those with a biomarker signature of risk, leveraging the knowledge gained from studies such as the report by McEvoy et al to improve public health,” he concluded.

 

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Familial transthyretin amyloid polyneuropathy

Curator: Larry H. Bernstein, MD, FCAP

LPBI

 

First-Ever Evidence that Patisiran Reduces Pathogenic, Misfolded TTR Monomers and Oligomers in FAP Patients

We reported data from our ongoing Phase 2 open-label extension (OLE) study of patisiran, an investigational RNAi therapeutic targeting transthyretin (TTR) for the treatment of TTR-mediated amyloidosis (ATTR amyloidosis) patients with familial amyloidotic polyneuropathy (FAP). Alnylam scientists and collaborators from The Scripps Research Institute and Misfolding Diagnostics, Inc. were able to measure the effects of patisiran on pathogenic, misfolded TTR monomers and oligomers in FAP patients. Results showed a rapid and sustained reduction in serum non-native conformations of TTR (NNTTR) of approximately 90%. Since NNTTR is pathogenic in ATTR amyloidosis and the level of NNTTR reduction correlated with total TTR knockdown, these results provide direct mechanistic evidence supporting the therapeutic hypothesis that TTR knockdown has the potential to result in clinical benefit. Furthermore, complete 12-month data from all 27 patients that enrolled in the patisiran Phase 2 OLE study showed sustained mean maximum reductions in total serum TTR of 91% for over 18 months and a mean 3.1-point decrease in mNIS+7 at 12 months, which compares favorably to an estimated increase in mNIS+7 of 13 to 18 points at 12 months based upon analysis of historical data sets in untreated FAP patients with similar baseline characteristics. Importantly, patisiran administration continues to be generally well tolerated out to 21 months of treatment.

Read our press release

View the non-native TTR poster (480 KB PDF)

View the complete 12-month patisiran Phase 2 OLE data presentation (620 KB PDF)

We are encouraged by these new data that provide continued support for our hypothesis that patisiran has the potential to halt neuropathy progression in patients with FAP. If these results are replicated in a randomized, double-blind, placebo-controlled study, we believe that patisiran could emerge as an important treatment option for patients suffering from this debilitating, progressive and life-threatening disease.

 

Hereditary ATTR Amyloidosis with Polyneuropathy (hATTR-PN)

ATTR amyloidosis is a progressive, life-threatening disease caused by misfolded transthyretin (TTR) proteins that accumulate as amyloid fibrils in multiple organs, but primarily in the peripheral nerves and heart. ATTR amyloidosis can lead to significant morbidity, disability, and mortality. The TTR protein is produced primarily in the liver and is normally a carrier for retinol binding protein – one of the vehicles used to transport vitamin A around the body.  Mutations in the TTR gene cause misfolding of the protein and the formation of amyloid fibrils that typically contain both mutant and wild-type TTR that deposit in tissues such as the peripheral nerves and heart, resulting in intractable peripheral sensory neuropathy, autonomic neuropathy, and/or cardiomyopathy.

Click to Enlarge

 

ATTR represents a major unmet medical need with significant morbidity and mortality. There are over 100 reported TTR mutations; the particular TTR mutation and the site of amyloid deposition determine the clinical manifestations of the disease whether it is predominantly symptoms of neuropathy or cardiomyopathy.

Specifically, hereditary ATTR amyloidosis with polyneuropathy (hATTR-PN), also known as familial amyloidotic polyneuropathy (FAP), is an inherited, progressive disease leading to death within 5 to 15 years. It is due to a mutation in the transthyretin (TTR) gene, which causes misfolded TTR proteins to accumulate as amyloid fibrils predominantly in peripheral nerves and other organs. hATTR-PN can cause sensory, motor, and autonomic dysfunction, resulting in significant disability and death.

It is estimated that hATTR-PN, also known as FAP, affects approximately 10,000 people worldwide.  Patients have a life expectancy of 5 to 15 years from symptom onset, and the only treatment options for early stage disease are liver transplantation and TTR stabilizers such as tafamidis (approved in Europe) and diflunisal.  Unfortunately liver transplantation has limitations, including limited organ availability as well as substantial morbidity and mortality. Furthermore, transplantation eliminates the production of mutant TTR but does not affect wild-type TTR, which can further deposit after transplantation, leading to cardiomyopathy and worsening of neuropathy. There is a significant need for novel therapeutics to treat patients who have inherited mutations in the TTR gene.

Our ATTR program is the lead effort in our Genetic Medicine Strategic Therapeutic Area (STAr) product development and commercialization strategy, which is focused on advancing innovative RNAi therapeutics toward genetically defined targets for the treatment of rare diseases with high unmet medical need.  We are developing patisiran (ALN-TTR02), an intravenously administered RNAi therapeutic, to treat the hATTR-PN form of the disease.

Patisiran for the Treatment hATTR-PN

APOLLO Phase 3 Trial

In 2012, Alnylam entered into an exclusive alliance with Genzyme, a Sanofi company, to develop and commercialize RNAi therapeutics, including patisiran and revusiran, for the treatment of ATTR amyloidosis in Japan and the broader Asian-Pacific region. In early 2014, this relationship was extended as a significantly broader alliance to advance RNAi therapeutics as genetic medicines. Under this new agreement, Alnylam will lead development and commercialization of patisiran in North America and Europe while Genzyme will develop and commercialize the product in the rest of world.

 

Hereditary ATTR Amyloidosis with Cardiomyopathy (hATTR-CM)

ATTR amyloidosis is a progressive, life-threatening disease caused by misfolded transthyretin (TTR) proteins that accumulate as amyloid fibrils in multiple organs, but primarily in the peripheral nerves and heart. ATTR amyloidosis can lead to significant morbidity, disability, and mortality. The TTR protein is produced primarily in the liver and is normally a carrier for retinol binding protein – one of the vehicles used to transport vitamin A around the body.  Mutations in the TTR gene cause misfolding of the protein and the formation of amyloid fibrils that typically contain both mutant and wild-type TTR that deposit in tissues such as the peripheral nerves and heart, resulting in intractable peripheral sensory neuropathy, autonomic neuropathy, and/or cardiomyopathy.

Click to Enlarge                            http://www.alnylam.com/web/assets/tetramer.jpg

ATTR represents a major unmet medical need with significant morbidity and mortality. There are over 100 reported TTR mutations; the particular TTR mutation and the site of amyloid deposition determine the clinical manifestations of the disease, whether it is predominantly symptoms of neuropathy or cardiomyopathy.

Specifically, hereditary ATTR amyloidosis with cardiomyopathy (hATTR-CM), also known as familial amyloidotic cardiomyopathy (FAC), is an inherited, progressive disease leading to death within 2 to 5 years. It is due to a mutation in the transthyretin (TTR) gene, which causes misfolded TTR proteins to accumulate as amyloid fibrils primarily in the heart. Hereditary ATTR amyloidosis with cardiomyopathy can result in heart failure and death.

While the exact numbers are not known, it is estimated hATTR-CM, also known as FAC affects at least 40,000 people worldwide.  hATTR-CM is fatal within 2 to 5 years of diagnosis and treatment is currently limited to supportive care.  Wild-type ATTR amyloidosis (wtATTR amyloidosis), also known as senile systemic amyloidosis, is a nonhereditary, progressive disease leading to death within 2 to 5 years. It is caused by misfolded transthyretin (TTR) proteins that accumulate as amyloid fibrils in the heart. Wild-type ATTR amyloidosis can cause cardiomyopathy and result in heart failure and death. There are no approved therapies for the treatment of hATTR-CM or SSA; hence there is a significant unmet need for novel therapeutics to treat these patients.

Our ATTR program is the lead effort in our Genetic Medicine Strategic Therapeutic Area (STAr) product development and commercialization strategy, which is focused on advancing innovative RNAi therapeutics toward genetically defined targets for the treatment of rare diseases with high unmet medical need.  We are developing revusiran (ALN-TTRsc), a subcutaneously administered RNAi therapeutic for the treatment of hATTR-CM.

Revusiran for the Treatment of hATTR-CM

ENDEAVOUR Phase 3 Trial

In 2012, Alnylam entered into an exclusive alliance with Genzyme, a Sanofi company, to develop and commercialize RNAi therapeutics, including patisiran and revusiran, for the treatment of ATTR amyloidosis in Japan and the broader Asian-Pacific region. In early 2014, this relationship was extended as a broader alliance to advance RNAi therapeutics as genetic medicines. Under this new agreement, Alnylam and Genzyme have agreed to co-develop and co-commercialize revusiran in North America and Europe, with Genzyme developing and commercializing the product in the rest of world. This broadened relationship on revusiran is aimed at expanding and accelerating the product’s global value.

Pre-Clinical Data and Advancement of ALN-TTRsc02 for Transthyretin-Mediated Amyloidosis

We presented pre-clinical data with ALN-TTRsc02, an investigational RNAi therapeutic targeting transthyretin (TTR) for the treatment of TTR-mediated amyloidosis (ATTR amyloidosis).  In pre-clinical studies, including those in non-human primates (NHPs), ALN-TTRsc02 achieved potent and highly durable knockdown of serum TTR of up to 99% with multi-month durability achieved after just a single dose, supportive of a potentially once quarterly dose regimen. Results from studies comparing TTR knockdown activity of ALN-TTRsc02 to that of revusiran showed that ALN-TTRsc02 has a markedly superior TTR knockdown profile.  Further, in initial rat toxicology studies, ALN-TTRsc02 was found to be generally well tolerated with no significant adverse events at doses as high as 100 mg/kg.

Read our press release

View the presentation

http://www.alnylam.com/product-pipeline/hereditary-attr-amyloidosis-with-cardiomyopathy/

 

Emerging Therapies for Transthyretin Cardiac Amyloidosis Could Herald a New Era for the Treatment of HFPEF

Oct 14, 2015   |  Adam Castano, MDDavid Narotsky, MDMathew S. Maurer, MD, FACC

http://www.acc.org/latest-in-cardiology/articles/2015/10/13/08/35/emerging-therapies-for-transthyretin-cardiac-amyloidosis#sthash.9xzc0rIe.dpuf

Heart failure with a preserved ejection fraction (HFPEF) is a clinical syndrome that has no pharmacologic therapies approved for this use to date. In light of failed medicines, cardiologists have refocused treatment strategies based on the theory that HFPEF is a heterogeneous clinical syndrome with different etiologies. Classification of HFPEF according to etiologic subtype may, therefore, identify cohorts with treatable pathophysiologic mechanisms and may ultimately pave the way forward for developing meaningful HFPEF therapies.1

A wealth of data now indicates that amyloid infiltration is an important mechanism underlying HFPEF. Inherited mutations in transthyretin cardiac amyloidosis (ATTRm) or the aging process in wild-type disease (ATTRwt) cause destabilization of the transthyretin (TTR) protein into monomers or oligomers, which aggregate into amyloid fibrils. These insoluble fibrils accumulate in the myocardium and result in diastolic dysfunction, restrictive cardiomyopathy, and eventual congestive heart failure (Figure 1). In an autopsy study of HFPEF patients, almost 20% without antemortem suspicion of amyloid had left ventricular (LV) TTR amyloid deposition.2 Even more resounding evidence for the contribution of TTR amyloid to HFPEF was a study in which 120 hospitalized HFPEF patients with LV wall thickness ≥12 mm underwent technetium-99m 3,3-diphosphono-1,2-propranodicarboxylic acid (99mTc-DPD) cardiac imaging,3,4 a bone isotope known to have high sensitivity and specificity for diagnosing TTR cardiac amyloidosis.5,6 Moderate-to-severe myocardial uptake indicative of TTR cardiac amyloid deposition was detected in 13.3% of HFPEF patients who did not have TTR gene mutations. Therefore, TTR cardiac amyloid deposition, especially in older adults, is not rare, can be easily identified, and may contribute to the underlying pathophysiology of HFPEF.

Figure 1

As no U.S. Food and Drug Administration-approved drugs are currently available for the treatment of HFPEF or TTR cardiac amyloidosis, the development of medications that attenuate or prevent TTR-mediated organ toxicity has emerged as an important therapeutic goal. Over the past decade, a host of therapies and therapeutic drug classes have emerged in clinical trials (Table 1), and these may herald a new direction for treating HFPEF secondary to TTR amyloid.

Table 1

TTR Silencers (siRNA and Antisense Oligonucleotides)

siRNA

Ribonucleic acid interference (RNAi) has surfaced as an endogenous cellular mechanism for controlling gene expression. Small interfering RNAs (siRNAs) delivered into cells can disrupt the production of target proteins.7,8 A formulation of lipid nanoparticle and triantennary N-acetylgalactosamine (GalNAc) conjugate that delivers siRNAs to hepatocytes is currently in clinical trials.9 Prior research demonstrated these GalNAc-siRNA conjugates result in robust and durable knockdown of a variety of hepatocyte targets across multiple species and appear to be well suited for suppression of TTR gene expression and subsequent TTR protein production.

The TTR siRNA conjugated to GalNAc, ALN-TTRSc, is now under active investigation as a subcutaneous injection in phase 3 clinical trials in patients with TTR cardiac amyloidosis.10 Prior phase 2 results demonstrated that ALN-TTRSc was generally well tolerated in patients with significant TTR disease burden and that it reduced both wild-type and mutant TTR gene expression by a mean of 87%. Harnessing RNAi technology appears to hold great promise for treating patients with TTR cardiac amyloidosis. The ability of ALN-TTRSc to lower both wild-type and mutant proteins may provide a major advantage over liver transplantation, which affects the production of only mutant protein and is further limited by donor shortage, cost, and need for immunosuppression.

Antisense Oligonucleotides

Antisense oligonucleotides (ASOs) are under clinical investigation for their ability to inhibit hepatic expression of amyloidogenic TTR protein. Currently, the ASO compound, ISIS-TTRRx, is under investigation in a phase 3 multicenter, randomized, double-blind, placebo-controlled clinical trial in patients with familial amyloid polyneuropathy (FAP).11 The primary objective is to evaluate its efficacy as measured by change in neuropathy from baseline relative to placebo. Secondary measures will evaluate quality of life (QOL), modified body mass index (mBMI) by albumin, and pharmacodynamic effects on retinol binding protein. Exploratory objectives in a subset of patients with LV wall thickness ≥13 mm without a history of persistent hypertension will examine echocardiographic parameters, N-terminal pro–B-type natriuretic peptide (NT-proBNP), and polyneuropathy disability score relative to placebo. These data will facilitate analysis of the effect of antisense oligonucleotide-mediated TTR suppression on the TTR cardiac phenotype with a phase 3 trial anticipated to begin enrollment in 2016.

TTR Stabilizers (Diflunisal, Tafamidis)

Diflunisal

Several TTR-stabilizing agents are in various stages of clinical trials. Diflunisal, a traditionally used and generically available nonsteroidal anti-inflammatory drug (NSAID), binds and stabilizes familial TTR variants against acid-mediated fibril formation in vitro and is now in human clinical trials.12,13 The use of diflunisal in patients with TTR cardiac amyloidosis is controversial given complication of chronic inhibition of cyclooxygenase (COX) enzymes, including gastrointestinal bleeding, renal dysfunction, fluid retention, and hypertension that may precipitate or exacerbate heart failure in vulnerable individuals.14-17 In TTR cardiac amyloidosis, an open-label cohort study suggested that low-dose diflunisal with careful monitoring along with a prophylactic proton pump inhibitor could be safely administered to compensated patients.18 An association was observed, however, between chronic diflunisal use and adverse changes in renal function suggesting that advanced kidney disease may be prohibitive in diflunisal therapy.In FAP patients with peripheral or autonomic neuropathy randomized to diflunisal or placebo, diflunisal slowed progression of neurologic impairment and preserved QOL over two years of follow-up.19 Echocardiography demonstrated cardiac involvement in approximately 50% of patients.20 Longer-term safety and efficacy data over an average 38 ± 31 months in 40 Japanese patients with hereditary ATTR amyloidosis who were not candidates for liver transplantation showed that diflunisal was mostly well tolerated.12 The authors cautioned the need for attentive monitoring of renal function and blood cell counts. Larger multicenter collaborations are needed to determine diflunisal’s true efficacy in HFPEF patients with TTR cardiac amyloidosis.

Tafamidis

Tafamidis is under active investigation as a novel compound that binds to the thyroxine-binding sites of the TTR tetramer, inhibiting its dissociation into monomers and blocking the rate-limiting step in the TTR amyloidogenesis cascade.21 The TTR compound was shown in an 18-month double-blind, placebo-controlled trial to slow progression of neurologic symptoms in patients with early-stage ATTRm due to the V30M mutation.22 When focusing on cardiomyopathy in a phase 2, open-label trial, tafamidis also appeared to effectively stabilize TTR tetramers in non-V30M variants, wild-type and V122I, as well as biochemical and echocardiographic parameters.23,24 Preliminary data suggests that clinically stabilized patients had shorter disease duration, lower cardiac biomarkers, less myocardial thickening, and higher EF than those who were not stabilized, suggesting early institution of therapy may be beneficial. A phase 3 trial has completed enrollment and will evaluate the efficacy, safety, and tolerability of tafamidis 20 or 80 mg orally vs. placebo.25 This will contribute to long-term safety and efficacy data needed to determine the therapeutic effects of tafamidis among ATTRm variants.

Amyloid Degraders (Doxycycline/TUDCA and Anti-SAP Antibodies)

Doxycycline/TUDCA

While silencer and stabilizer drugs are aimed at lowering amyloidogenic precursor protein production, they cannot remove already deposited fibrils in an infiltrated heart. Removal of already deposited fibrils by amyloid degraders would be an important therapeutic strategy, particularly in older adults with heavily infiltrated hearts reflected by thick walls, HFPEF, systolic heart failure, and restrictive cardiomyopathy. Combined doxycycline and tauroursodeoxycholic acid (TUDCA) disrupt TTR amyloid fibrils and appeared to have an acceptable safety profile in a small phase 2 open-label study among 20 TTR patients. No serious adverse reactions or clinical progression of cardiac or neuropathic involvement was observed over one year.26 An active phase 2, single-center, open-label, 12-month study will assess primary outcome measures including mBMI, neurologic impairment score, and NT-proBNP.27 Another phase 2 study is examining the tolerability and efficacy of doxycycline/TUDCA over an 18-month period in patients with TTR amyloid cardiomyopathy.28 Additionally, a study in patients with TTR amyloidosis is ongoing to determine the effect of doxycycline alone on neurologic function, cardiac biomarkers, echocardiographic parameters, modified body mass index, and autonomic neuropathy.29

Anti-SAP Antibodies

In order to safely clear established amyloid deposits, the role of the normal, nonfibrillar plasma glycoprotein present in all human amyloid deposits, serum amyloid P component (SAP), needs to be more clearly understood.30 In mice with amyloid AA type deposits, administration of antihuman SAP antibody triggered a potent giant cell reaction that removed massive visceral amyloid deposits without adverse effects.31 In humans with TTR cardiac amyloidosis, anti-SAP antibody treatments could be feasible because the bis-D proline compound, CPHPC, is capable of clearing circulating human SAP, which allow anti-SAP antibodies to reach residual deposited SAP. In a small, open-label, single-dose-escalation, phase 1 trial involving 15 patients with systemic amyloidosis, none of whom had clinical evidence of cardiac amyloidosis, were treated with CPHPC followed by human monoclonal IgG1 anti-SAP antibody.32 No serious adverse events were reported and amyloid deposits were cleared from the liver, kidney, and lymph node. Anti-SAP antibodies hold promise as a potential amyloid therapy because of their potential to target all forms of amyloid deposits across multiple tissue types.

Mutant or wild-type TTR cardiac amyloidoses are increasingly recognized as a cause of HFPEF. Clinicians need to be aware of this important HFPEF etiology because the diverse array of emerging disease-modifying agents for TTR cardiac amyloidosis in human clinical trials has the potential to herald a new era for the treatment of HFPEF.

References

  1. Maurer MS, Mancini D. HFpEF: is splitting into distinct phenotypes by comorbidities the pathway forward? J Am Coll Cardiol 2014;64:550-2.
  2. Mohammed SF, Mirzoyev SA, Edwards WD, et al. Left ventricular amyloid deposition in patients with heart failure and preserved ejection fraction. JACC Heart Fail 2014;2:113-22.
  3. González-López E, Gallego-Delgado M, Guzzo-Merello G, et al. Wild-type transthyretin amyloidosis as a cause of heart failure with preserved ejection fraction. Eur Heart J 2015.
  4. Castano A, Bokhari S, Maurer MS. Unveiling wild-type transthyretin cardiac amyloidosis as a significant and potentially modifiable cause of heart failure with preserved ejection fraction. Eur Heart J 2015 Jul 28. [Epub ahead of print]
  5. Rapezzi C, Merlini G, Quarta CC, et al. Systemic cardiac amyloidoses: disease profiles and clinical courses of the 3 main types. Circulation 2009;120:1203-12.
  6. Bokhari S, Castano A, Pozniakoff T, Deslisle S, Latif F, Maurer MS. (99m)Tc-pyrophosphate scintigraphy for differentiating light-chain cardiac amyloidosis from the transthyretin-related familial and senile cardiac amyloidoses. Circ Cardiovasc Imaging 2013;6:195-201.
  7. Fire A, Xu S, Montgomery MK, Kostas SA, Driver SE, Mello CC. Potent and specific genetic interference by double-stranded RNA in Caenorhabditis elegans. Nature 1998;391:806-11.
  8. Elbashir SM, Harborth J, Lendeckel W, Yalcin A, Weber K, Tuschl T. Duplexes of 21-nucleotide RNAs mediate RNA interference in cultured mammalian cells. Nature 2001;411:494-8.
  9. Kanasty R, Dorkin JR, Vegas A, Anderson D. Delivery materials for siRNA therapeutics. Nature Mater 2013;12:967-77.
  10. U.S. National Institutes of Health. Phase 2 Study to Evaluate ALN-TTRSC in Patients With Transthyretin (TTR) Cardiac Amyloidosis (ClinicalTrials.gov website). 2014. Available at: https://www.clinicaltrials.gov/ct2/show/NCT01981837. Accessed 8/19/2015.
  11. U.S. National Institutes of Health. Efficacy and Safety of ISIS-TTRRx in Familial Amyloid Polyneuropathy (Clinical Trials.gov Website. 2013. Available at: http://www.clinicaltrials.gov/ct2/show/NCT01737398. Accessed 8/19/2015.
  12. Sekijima Y, Dendle MA, Kelly JW. Orally administered diflunisal stabilizes transthyretin against dissociation required for amyloidogenesis. Amyloid 2006;13:236-49.
  13. Tojo K, Sekijima Y, Kelly JW, Ikeda S. Diflunisal stabilizes familial amyloid polyneuropathy-associated transthyretin variant tetramers in serum against dissociation required for amyloidogenesis. Neurosci Res 2006;56:441-9.
  14. Epstein M. Non-steroidal anti-inflammatory drugs and the continuum of renal dysfunction. J Hypertens Suppl 2002;20:S17-23.
  15. Wallace JL. Pathogenesis of NSAID-induced gastroduodenal mucosal injury. Best Pract Res Clin Gastroenterol 2001;15:691-703.
  16. Mukherjee D, Nissen SE, Topol EJ. Risk of cardiovascular events associated with selective COX-2 inhibitors. JAMA 2001;286:954-9.
  17. Page J, Henry D. Consumption of NSAIDs and the development of congestive heart failure in elderly patients: an underrecognized public health problem. Arch Intern Med 2000;160:777-84.
  18. Castano A, Helmke S, Alvarez J, Delisle S, Maurer MS. Diflunisal for ATTR cardiac amyloidosis. Congest Heart Fail 2012;18:315-9.
  19. Berk JL, Suhr OB, Obici L, et al. Repurposing diflunisal for familial amyloid polyneuropathy: a randomized clinical trial. JAMA 2013;310:2658-67.
  20. Quarta CCF, Solomon RH Suhr SD, et al. The prevalence of cardiac amyloidosis in familial amyloidotic polyneuropathy with predominant neuropathy: The Diflunisal Trial. International Symposium on Amyloidosis 2014:88-9.
  21. Hammarstrom P, Jiang X, Hurshman AR, Powers ET, Kelly JW. Sequence-dependent denaturation energetics: A major determinant in amyloid disease diversity. Proc Natl Acad Sci U S A 2002;99 Suppl 4:16427-32.
  22. Coelho T, Maia LF, Martins da Silva A, et al. Tafamidis for transthyretin familial amyloid polyneuropathy: a randomized, controlled trial. Neurology 2012;79:785-92.
  23. Merlini G, Plante-Bordeneuve V, Judge DP, et al. Effects of tafamidis on transthyretin stabilization and clinical outcomes in patients with non-Val30Met transthyretin amyloidosis. J Cardiovasc Transl Res 2013;6:1011-20.
  24. Maurer MS, Grogan DR, Judge DP, et al. Tafamidis in transthyretin amyloid cardiomyopathy: effects on transthyretin stabilization and clinical outcomes. Circ Heart Fail 2015;8:519-26.
  25. U.S. National Institutes of Health. Safety and Efficacy of Tafamidis in Patients With Transthyretin Cardiomyopathy (ATTR-ACT) (ClinicalTrials.gov website). 2014. Available at: http://www.clinicaltrials.gov/show/NCT01994889. Accessed 8/19/2015.
  26. Obici L, Cortese A, Lozza A, et al. Doxycycline plus tauroursodeoxycholic acid for transthyretin amyloidosis: a phase II study. Amyloid 2012;19 Suppl 1:34-6.
  27. U.S. National Institutes of Health. Safety, Efficacy and Pharmacokinetics of Doxycycline Plus Tauroursodeoxycholic Acid in Transthyretin Amyloidosis (ClinicalTrials.gov website). 2011. Available at: http://www.clinicaltrials.gov/ct2/show/NCT01171859. Accessed 8/19/2015.
  28. U.S. National Institutes of Health. Tolerability and Efficacy of a Combination of Doxycycline and TUDCA in Patients With Transthyretin Amyloid Cardiomyopathy (ClinicalTrials.gov website). 2013. Available at: http://www.clinicaltrials.gov/ct2/show/NCT01855360. Accessed 8/19/2015.
  29. U.S. National Institutes of Health. Safety and Effect of Doxycycline in Patients With Amyloidosis (ClinicalTrials.gov website).2015. Available at: https://clinicaltrials.gov/ct2/show/NCT01677286. Accessed 8/19/2015.
  30. Pepys MB, Dash AC. Isolation of amyloid P component (protein AP) from normal serum as a calcium-dependent binding protein. Lancet 1977;1:1029-31.
  31. Bodin K, Ellmerich S, Kahan MC, et al. Antibodies to human serum amyloid P component eliminate visceral amyloid deposits. Nature 2010;468:93-7.
  32. Richards DB, Cookson LM, Berges AC, et al. Therapeutic Clearance of Amyloid by Antibodies to Serum Amyloid P Component. N Engl J Med 2015;373:1106-14.

 

The Acid-Mediated Denaturation Pathway of Transthyretin Yields a Conformational Intermediate That Can Self-Assemble into Amyloid

Zhihong Lai , Wilfredo Colón , and Jeffery W. Kelly *
Department of Chemistry, Texas A&M University, College Station, Texas 77843-3255
Biochemistry199635 (20), pp 6470–6482   http://dx.doi.org:/10.1021/bi952501g
Publication Date (Web): May 21, 1996  Copyright © 1996 American Chemical Society

Transthyretin (TTR) amyloid fibril formation is observed during partial acid denaturation and while refolding acid-denatured TTR, implying that amyloid fibril formation results from the self-assembly of a conformational intermediate. The acid denaturation pathway of TTR has been studied in detail herein employing a variety of biophysical methods to characterize the intermediate(s) capable of amyloid fibril formation. At physiological concentrations, tetrameric TTR remains associated from pH 7 to pH 5 and is incapable of amyloid fibril formation. Tetrameric TTR dissociates to a monomer in a process that is dependent on both pH and protein concentration below pH 5. The extent of amyloid fibril formation correlates with the concentration of the TTR monomer having an altered, but defined, tertiary structure over the pH range of 5.0−3.9. The inherent Trp fluorescence-monitored denaturation curve of TTR exhibits a plateau over the pH range where amyloid fibril formation is observed (albeit at a higher concentration), implying that a steady-state concentration of the amyloidogenic intermediate with an altered tertiary structure is being detected. Interestingly, 1-anilino-8-naphthalenesulfonate fluorescence is at a minimum at the pH associated with maximal amyloid fibril formation (pH 4.4), implying that the amyloidogenic intermediate does not have a high extent of hydrophobic surface area exposed, consistent with a defined tertiary structure. Transthyretin has two Trp residues in its primary structure, Trp-41 and Trp-79, which are conveniently located far apart in the tertiary structure of TTR. Replacement of each Trp with Phe affords two single Trp containing variants which were used to probe local pH-dependent tertiary structural changes proximal to these chromophores. The pH-dependent fluorescence behavior of the Trp-79-Phe mutant strongly suggests that Trp-41 is located near the site of the tertiary structural rearrangement that occurs in the formation of the monomeric amyloidogenic intermediate, likely involving the C-strand−loop−D-strand region. Upon further acidification of TTR (below pH 4.4), the structurally defined monomeric amyloidogenic intermediate begins to adopt alternative conformations that are not amyloidogenic, ultimately forming an A-state conformation below pH 3 which is also not amyloidogenic. In summary, analytical equilibrium ultracentrifugation, SDS−PAGE, far- and near-UV CD, fluorescence, and light scattering studies suggest that the amyloidogenic intermediate is a monomeric predominantly β-sheet structure having a well-defined tertiary structure.

 

Prevention of Transthyretin Amyloid Disease by Changing Protein Misfolding Energetics

Per Hammarström*, R. Luke Wiseman*, Evan T. Powers, Jeffery W. Kelly   + Author Affiliations

Science  31 Jan 2003; 299(5607):713-716   http://dx.doi.org:/10.1126/science.1079589

Genetic evidence suggests that inhibition of amyloid fibril formation by small molecules should be effective against amyloid diseases. Known amyloid inhibitors appear to function by shifting the aggregation equilibrium away from the amyloid state. Here, we describe a series of transthyretin amyloidosis inhibitors that functioned by increasing the kinetic barrier associated with misfolding, preventing amyloidogenesis by stabilizing the native state. The trans-suppressor mutation, threonine 119 → methionine 119, which is known to ameliorate familial amyloid disease, also functioned through kinetic stabilization, implying that this small-molecule strategy should be effective in treating amyloid diseases.

 

Rational design of potent human transthyretin amyloid disease inhibitors

Thomas Klabunde1,2, H. Michael Petrassi3, Vibha B. Oza3, Prakash Raman3, Jeffery W. Kelly3 & James C. Sacchettini1

Nature Structural & Molecular Biology 2000; 7: 312 – 321.                http://dx.doi.org:/10.1038/74082

The human amyloid disorders, familial amyloid polyneuropathy, familial amyloid cardiomyopathy and senile systemic amyloidosis, are caused by insoluble transthyretin (TTR) fibrils, which deposit in the peripheral nerves and heart tissue. Several nonsteroidal anti-inflammatory drugs and structurally similar compounds have been found to strongly inhibit the formation of TTR amyloid fibrils in vitro. These include flufenamic acid, diclofenac, flurbiprofen, and resveratrol. Crystal structures of the protein–drug complexes have been determined to allow detailed analyses of the protein–drug interactions that stabilize the native tetrameric conformation of TTR and inhibit the formation of amyloidogenic TTR. Using a structure-based drug design approach ortho-trifluormethylphenyl anthranilic acid and N-(meta-trifluoromethylphenyl) phenoxazine 4,6-dicarboxylic acid have been discovered to be very potent and specific TTR fibril formation inhibitors. This research provides a rationale for a chemotherapeutic approach for the treatment of TTR-associated amyloid diseases.

 

First European consensus for diagnosis, management, and treatment of transthyretin familial amyloid polyneuropathy

Adams, Davida; Suhr, Ole B.b; Hund, Ernstc; Obici, Laurad; Tournev, Ivailoe,f; Campistol, Josep M.g; Slama, Michel S.h; Hazenberg, Bouke P.i; Coelho, Teresaj; from the European Network for TTR-FAP (ATTReuNET)

Current Opin Neurol: Feb 2016; 29 – Issue – p S14–S26      http://dx.doi.org:/10.1097/WCO.0000000000000289

Purpose of review: Early and accurate diagnosis of transthyretin familial amyloid polyneuropathy (TTR-FAP) represents one of the major challenges faced by physicians when caring for patients with idiopathic progressive neuropathy. There is little consensus in diagnostic and management approaches across Europe.

Recent findings: The low prevalence of TTR-FAP across Europe and the high variation in both genotype and phenotypic expression of the disease means that recognizing symptoms can be difficult outside of a specialized diagnostic environment. The resulting delay in diagnosis and the possibility of misdiagnosis can misguide clinical decision-making and negatively impact subsequent treatment approaches and outcomes.

Summary: This review summarizes the findings from two meetings of the European Network for TTR-FAP (ATTReuNET). This is an emerging group comprising representatives from 10 European countries with expertise in the diagnosis and management of TTR-FAP, including nine National Reference Centres. The current review presents management strategies and a consensus on the gold standard for diagnosis of TTR-FAP as well as a structured approach to ongoing multidisciplinary care for the patient. Greater communication, not just between members of an individual patient’s treatment team, but also between regional and national centres of expertise, is the key to the effective management of TTR-FAP.

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Transthyretin familial amyloid polyneuropathy (TTR-FAP) is a highly debilitating and irreversible neurological disorder presenting symptoms of progressive sensorimotor and autonomic neuropathy [1▪,2▪,3]. TTR-FAP is caused by misfolding of the transthyretin (TTR) protein leading to protein aggregation and the formation of amyloid fibrils and, ultimately, to amyloidosis (commonly in the peripheral and autonomic nervous system and the heart) [4,5]. TTR-FAP usually proves fatal within 7–12 years from the onset of symptoms, most often due to cardiac dysfunction, infection, or cachexia [6,7▪▪].

The prevalence and disease presentation of TTR-FAP vary widely within Europe. In endemic regions (northern Portugal, Sweden, Cyprus, and Majorca), patients tend to present with a distinct genotype in large concentrations, predominantly a Val30Met substitution in the TTR gene [8–10]. In other areas of Europe, the genetic footprint of TTR-FAP is more varied, with less typical phenotypic expression [6,11]. For these sporadic or scattered cases, a lack of awareness among physicians of variable clinical features and limited access to diagnostic tools (i.e., pathological studies and genetic screening) can contribute to high rates of misdiagnosis and poorer patient outcomes [1▪,11]. In general, early and late-onset variants of TTR-FAP, found within endemic and nonendemic regions, present several additional diagnostic challenges [11,12,13▪,14].

Delay in the time to diagnosis is a major obstacle to the optimal management of TTR-FAP. With the exception of those with a clearly diagnosed familial history of FAP, patients still invariably wait several years between the emergence of first clinical signs and accurate diagnosis [6,11,14]. The timely initiation of appropriate treatment is particularly pertinent, given the rapidity and irreversibility with which TTR-FAP can progress if left unchecked, as well as the limited effectiveness of available treatments during the later stages of the disease [14]. This review aims to consolidate the existing literature and present an update of the best practices in the management of TTR-FAP in Europe. A summary of the methods used to achieve a TTR-FAP diagnosis is presented, as well as a review of available treatments and recommendations for treatment according to disease status.

Patients with TTR-FAP can present with a range of symptoms [11], and care should be taken to acquire a thorough clinical history of the patient as well as a family history of genetic disease. Delay in diagnosis is most pronounced in areas where TTR-FAP is not endemic or when there is no positive family history [1▪]. TTR-FAP and TTR-familial amyloid cardiomyopathy (TTR-FAC) are the two prototypic clinical disease manifestations of a broader disease spectrum caused by an underlying hereditary ATTR amyloidosis [19]. In TTR-FAP, the disease manifestation of neuropathy is most prominent and definitive for diagnosis, whereas cardiomyopathy often suggests TTR-FAC. However, this distinction is often superficial because cardiomyopathy, autonomic neuropathy, vitreous opacities, kidney disease, and meningeal involvement all may be present with varying severity for each patient with TTR-FAP.

Among early onset TTR-FAP with usually positive family history, symptoms of polyneuropathy present early in the disease process and usually predominate throughout the progression of the disease, making neurological testing an important diagnostic aid [14]. Careful clinical examination (e.g., electromyography with nerve conduction studies and sympathetic skin response, quantitative sensation test, quantitative autonomic test) can be used to detect, characterize, and scale the severity of neuropathic abnormalities involving small and large nerve fibres [10]. Although a patient cannot be diagnosed definitively with TTR-FAP on the basis of clinical presentation alone, symptoms suggesting the early signs of peripheral neuropathy, autonomic dysfunction, and cardiac conduction disorders or infiltrative cardiomyopathy are all indicators that further TTR-FAP diagnostic investigation is warranted. Late-onset TTR-FAP often presents as sporadic cases with distinct clinical features (e.g., milder autonomic dysfunction) and can be more difficult to diagnose than early-onset TTR-FAP (Table 2) [1▪,11,12,13▪,14,20].

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Genetic testing is carried out to allow detection of specific amyloidogenic TTR mutations (Table 1), using varied techniques depending on the expertise and facilities available in each country (Table S2, http://links.lww.com/CONR/A39). A targeted approach to detect a specific mutation can be used for cases belonging to families with previous diagnosis. In index cases of either endemic and nonendemic regions that do not have a family history of disease, are difficult to confirm, and have atypical symptoms, TTR gene sequencing is required for the detection of both predicted and new amyloidogenic mutations [26,27].

Following diagnosis, the neuropathy stage and systemic extension of the disease should be determined in order to guide the next course of treatment (Table 4) [3,30,31]. The three stages of TTR-FAP severity are graded according to a patient’s walking disability and degree of assistance required [30]. Systemic assessment, especially of the heart, eyes, and kidney, is also essential to ensure all aspects of potential impact of the disease can be detected [10].

Table 4

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The goals of cardiac investigations are to detect serious conduction disorders with the risk of sudden death and infiltrative cardiomyopathy. Electrocardiograms (ECG), Holter-ECG, and intracardiac electrophysiology study are helpful to detect conduction disorders. Echocardiograms, cardiac magnetic resonance imaging, scintigraphy with bone tracers, and biomarkers (e.g., brain natriuretic peptide, troponin) can all help to diagnose infiltrative cardiomyopathy[10]. An early detection of cardiac abnormalities has obvious benefits to the patient, given that the prophylactic implantation of pacemakers was found to prevent 25% of major cardiac events in TTR-FAP patients followed up over an average of 4 years [32▪▪]. Assessment of cardiac denervation with 123-iodine meta-iodobenzylguanidine is a powerful prognostic marker in patients diagnosed with FAP [33].

…..

Tafamidis

Tafamidis is a first-in-class therapy that slows the progression of TTR amyloidogenesis by stabilizing the mutant TTR tetramer, thereby preventing its dissociation into monomers and amyloidogenic and toxic intermediates [55,56]. Tafamidis is currently indicated in Europe for the treatment of TTR amyloidosis in adult patients with stage I symptomatic polyneuropathy to delay peripheral neurological impairment [57].

In an 18-month, double-blind, placebo-controlled study of patients with early-onset Val30Met TTR-FAP, tafamidis was associated with a 52% lower reduction in neurological deterioration (P = 0.027), a preservation of nerve function, and TTR stabilization versus placebo [58▪▪]. However, only numerical differences were found for the coprimary endpoints of neuropathy impairment [neuropathy impairment score in the lower limb (NIS-LL) responder rates of 45.3% tafamidis vs 29.5% placebo; P = 0.068] and quality of life scores [58▪▪]. A 12-month, open-label extension study showed that the reduced rates of neurological deterioration associated with tafamidis were sustained over 30 months, with earlier initiation of tafamidis linking to better patient outcomes (P = 0.0435) [59▪]. The disease-slowing effects of tafamidis may be dependent on the early initiation of treatment. In an open-label study with Val30Met TTR-FAP patients with late-onset and advanced disease (NIS-LL score >10, mean age 56.4 years), NIS-LL and disability scores showed disease progression despite 12 months of treatment with tafamidis, marked by a worsening of neuropathy stage in 20% and the onset of orthostatic hypotension in 22% of patients at follow-up [60▪].

Tafamidis is not only effective in patients exhibiting the Val30Met mutation; it also has proven efficacy, in terms of TTR stabilization, in non-Val30Met patients over 12 months [61]. Although tafamidis has demonstrated safe use in patients with TTR-FAP, care should be exercised when prescribing to those with existing digestive problems (e.g., diarrhoea, faecal incontinence) [60▪].

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Diflunisal

Diflunisal is a nonsteroidal anti-inflammatory drug (NSAID) that, similar to tafamidis, slows the rate of amyloidogenesis by preventing the dissociation, misfolding, and misassembly of the mutated TTR tetramer [62,63]. Off-label use has been reported for patients with stage I and II disease, although diflunisal is not currently licensed for the treatment of TTR-FAP.

Evidence for the clinical effectiveness of diflunisal in TTR-FAP derives from a placebo-controlled, double-blind, 24-month study in 130 patients with clinically detectable peripheral or autonomic neuropathy[64▪]. The deterioration in NIS scores was significantly more pronounced in patients receiving placebo compared with those taking diflunisal (P = 0.001), and physical quality of life measures showed significant improvement among diflunisal-treated patients (P = 0.001). Notable during this study was the high rate of attrition in the placebo group, with 50% more placebo-treated patients dropping out of this 2-year study as a result of disease progression, advanced stage of the disease, and varied mutations.

One retrospective analysis of off-label use of diflunisal in patients with TTR-FAP reported treatment discontinuation in 57% of patients because of adverse events that were largely gastrointestinal [65]. Conclusions on the safety of diflunisal in TTR-FAP will depend on further investigations on the impact of known cardiovascular and renal side-effects associated with the NSAID drug class [66,67].

 

 

 

 

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