Ciraparantag, an anticoagulant reversal drug: mechanism of action, pharmacokinetics, and reversal of anticoagulants.

Ciraparantag, an anticoagulant reversal agent, is a small molecule specifically designed to bind noncovalently by charge-charge interaction to unfractionated heparin and low-molecular-weight heparin. It shows binding characteristics that are similar to those of direct oral anticoagulants (DOACs). A dynamic light-scattering methodology was used to demonstrate ciraparantag's binding to the heparins and DOACs and its lack of binding to a variety of proteins including coagulation factors and commonly used drugs. Ciraparantag reaches maximum concentration within minutes after IV administration with a half-life of 12 to 19 minutes. It is primarily hydrolyzed by serum peptidases into 2 metabolites, neither of which has substantial activity. Ciraparantag and its metabolites are recovered almost entirely in the urine. In animal models of bleeding (rat tail transection and liver laceration), a single IV dose of ciraparantag given at peak concentrations of the anticoagulant, but before the bleeding injury, significantly reduced the blood loss. Ciraparantag, given after the bleeding injury, also significantly reduced blood loss. It appears to have substantial ability to reduce blood loss in animal models in which a variety of anticoagulants are used and has potential as a useful DOAC reversal agent.

Ciraparantag reverses the anticoagulant activity of apixaban and rivaroxaban in healthy elderly subjects.

AIMS: Ciraparantag is a reversal agent for anticoagulants including direct oral anticoagulants. The aim was to evaluate the efficacy and safety of ciraparantag to reverse anticoagulation induced by apixaban or rivaroxaban in healthy elderly adults. METHODS AND RESULTS: Two randomized, placebo-controlled, dose-ranging trials conducted in healthy subjects aged 50-75 years. Subjects received apixaban (Study 1) 10 mg orally twice daily for 3.5 days or rivaroxaban (Study 2) 20 mg orally once daily for 3 days. At steady-state anticoagulation subjects were randomized 3:1 to a single intravenous dose of ciraparantag (Study 1: 30, 60, or 120 mg; Study 2: 30, 60, 120, or 180 mg) or placebo. Efficacy was based on correction of the whole blood clotting time (WBCT) at multiple timepoints over 24 h. Subjects and technicians performing WBCT testing were blinded to treatment. Complete reversal of WBCT within 1 h post-dose and sustained through 5 h (apixaban) or 6 h (rivaroxaban) was dose related and observed with apixaban in 67%, 100%, 100%, and 17% of subjects receiving ciraparantag 30 mg, 60 mg, 120 mg, or placebo, respectively; and with rivaroxaban in 58%, 75%, 67%, 100%, and 13% of subjects receiving ciraparantag 30 mg, 60 mg, 120 mg, 180 mg, or placebo, respectively. Adverse events related to ciraparantag were mild, transient hot flashes or flushing. CONCLUSIONS: Ciraparantag provides a dose-related reversal of anticoagulation induced by steady-state dosing of apixaban or rivaroxaban. Sustained reversal was achieved with 60 mg ciraparantag for apixaban and 180 mg ciraparantag for rivaroxaban. All doses of ciraparantag were well tolerated.

A Novel Whole Blood Point-of-Care Coagulometer to Measure the Effect of Direct Oral Anticoagulants and Heparins.

The direct oral anticoagulants (DOACs) currently require no monitoring for routine therapy of atrial fibrillation or venous thromboembolism. Measurement of activity, however, may be important in patients with major and life-threatening bleeding, patients needing emergent surgery, in reversal situations, or in patients at high risk of bleeding or thrombosis due to underlying conditions. For these patients, a widely available and rapid turnaround assay would be optimal. To date, there is no such assay available, especially for the direct factor Xa inhibitors. This report describes the performance of a new, rapid turnaround, point-of-care (PoC) assay for measuring the activity of a range of anticoagulants, including DOACs and heparins, in emergency situations and for routine measurement in high-risk patients. Perosphere Technologies' PoC coagulometer is a handheld instrument that performs individual coagulation tests on samples of fresh whole blood (∼10 µL) with clotting activated by glass contact and endpoint determination performed by infrared spectroscopy. In preclinical studies using rats anticoagulated with therapeutic doses of edoxaban or enoxaparin, the PoC coagulometer showed a strong linear correlation between pharmacokinetic parameters and clotting time with edoxaban (r 2 = 0.994) and with enoxaparin (r 2 = 0.967). These preclinical results suggest that this PoC coagulometer would be ideal to assess the pharmacodynamic effects of anticoagulants and their reversal agents. The PoC bedside instrument delivers results within minutes and requires no more than a drop of whole blood. Studies are underway to confirm these results in humans and to further characterize the performance of the instrument.

Nonclinical Safety Assessment of PER977: A Small Molecule Reversal Agent for New Oral Anticoagulants and Heparins.

A new molecular entity, PER977 (di-arginine piperazine), is in clinical development as an anticoagulant reversal agent for new oral anticoagulants and heparins. The good laboratory practices (GLP)-compliant studies were conducted to evaluate the toxicity of PER977 and its primary metabolite, 1,4-bis(3-aminopropyl)piperazine (BAP). PER977 and BAP were negative for systemic toxicity in dogs and rats. PER977 was rapidly eliminated from the blood with little to no accumulation. PER977 was negative for genotoxicity and did not alter neurological, respiratory, or cardiovascular function. Maximum tolerated doses for PER977 were 40 (rat) and 35 mg/kg (dog), and greater than 80 mg/kg (rat) for BAP. The no observable adverse effect level (NOAEL) for 14-day intravenous exposure to both rats and dogs was 20 mg/kg/d. For BAP, the NOAELs for 14-day intravenous exposure to rats and dogs were 5 and 20 mg/kg, respectively. Based on these results, a safe and conservative dose level of 19.4 mg/d was used for the PER977 first in human study.

Single-dose ciraparantag safely and completely reverses anticoagulant effects of edoxaban.

Of the new direct oral anticoagulants, direct factor Xa inhibitors are limited by the absence of a proven reversal agent. We assessed the safety, tolerability and impact on anticoagulation reversal of ciraparantag (PER977) alone and following a 60 mg dose of the FXa inhibitor edoxaban. Escalating, single IV doses of ciraparantag were administered alone and following a 60 mg oral dose of edoxaban in a double-blind, placebo-controlled fashion to healthy subjects. Serial assessments of the pharmacokinetics and pharmacodynamic effects of ciraparantag were performed. Eighty male subjects completed the study. Following edoxaban (60 mg), a single IV dose of ciraparantag (100 to 300 mg) demonstrated full reversal of anticoagulation within 10 minutes and sustained for 24 hours. Fibrin diameter within clots was restored to normal 30 minutes after a single dose of 100 to 300 mg ciraparantag as determined by scanning electron microscopy and change in fibrin diameter quantified by automated image analysis. Potentially related adverse events were periorbital and facial flushing and cool sensation following IV injection of ciraparantag. Renal excretion of ciraparantag metabolite was the main elimination route. There was no evidence of procoagulant activity following ciraparantag as assessed by D-dimer, prothrombin fragments 1.2, and tissue factor pathway inhibitor levels. In conclusion, ciraparantag in healthy subjects is safe and well tolerated with minor, non-dose limiting adverse events. Baseline haemostasis was restored from the anticoagulated state with doses of 100 to 300 mg ciraparantag within 10-30 minutes of administration and sustained for at least 24 hours.

Ciraparantag safely and completely reverses the anticoagulant effects of low molecular weight heparin.

Major bleeding with low molecular weight heparin (LMWH) therapy occurs in up to 5% of patients and its anticoagulation is only partially reversed by protamine sulfate. We studied the ability of ciraparantag (PER977), a novel agent that reverses LMWH in preclinical studies, to reverse LMWH in healthy volunteers. METHODS: In this phase 1/2 trial, 4 cohorts of 10 healthy volunteers received escalating doses of ciraparantag (100 to 300mg) or placebo (8:2 ratio) approximately 4h after a single subcutaneous dose of enoxaparin, 1.5mg/kg. Safety, pharmacokinetic and pharmacodynamic effects were assessed. RESULTS: Complete reversal of enoxaparin anticoagulation, measured by a reduction of whole blood clotting time, was observed in all subjects who received a single ciraparantag dose ranging from 100mg to 300mg. The anticoagulation reversal occurred rapidly after bolus injection and persisted for the duration of the study. At 12h and 24h, the differences in whole blood clotting time in the treated group compared to placebo were no longer significant, consistent with the decline in enoxaparin concentrations and anticoagulation effects. No procoagulant signals were detected as measured by D-dimer, F1.2, and tissue factor pathway inhibitor levels. Ciraparantag was well tolerated with only transient, minor side effects. CONCLUSION: Ciraparantag reverses the whole blood clotting time induced by enoxaparin in a dose related manner and produces no procoagulant signal or deleterious adverse events in doses up to 300mg.

Low-voltage planar-waveguide electrooptic prism scanner in Crystal-Ion-Sliced thin-film LiNbO3.

We report on the use of thin, i.e. 10 microm-thick, single-crystal LiNbO3, in low-voltage electrooptic prism scanners. These devices are fabricated by electric-field poling of a series of electrooptic prisms in a bulk crystal followed by high-energy ion implantation and subsequent etching of the poled samples. Such a single-crystal thin-film scanner, while having the same scanning functionality as with a bulk device, has an order-of-magnitude reduction in its required voltage; for example, a series of two prisms, of 2mm in total length, yields a deflection angle of 0.7 at 100V compared to more than 1.7kV for the same device in standard 200 microm-thick LiNbO3 wafers.

Reversal agents in development for the new oral anticoagulants.

The new oral anticoagulants have many advantages over vitamin K antagonists, but they are still associated with a troublesome incidence of major bleeding. Additionally, the absence of a reversal agent for the new oral anticoagulants is a barrier to their more widespread use. Currently, there are 3 potential reversal agents in development: idarucizumab is a humanized murine monoclonal antibody fragment directed specifically at dabigatran; andexanet alfa is a recombinant modified decoy factor Xa that binds to factor Xa inhibitors; and PER977 is a small molecule that binds to factor Xa and IIa inhibitors and to heparin-based anticoagulants through charge interaction. These agents have undergone phase I clinical testing, appear to be well tolerated in healthy volunteers, and are effective in neutralizing their respective targets. All 3 are currently undergoing or entering into a phase II or III clinical study. This article reviews the available data for idarucizumab, andexanet alfa, and PER977.

Oral delivery of proteins by biodegradable nanoparticles.

Successful administration of therapeutic proteins via the oral route has long eluded the drug delivery community; a variety of factors, both physical and physiological, have hindered the myriad approaches to increasing the bioavailability of orally administered therapeutic proteins, including: 1) pre-systemic degradation by enzymes and 2) poor penetration of the intestinal mucosa and epithelium. Even when bypassing the harsh, acidic environment of the stomach, the intestines pose significant obstacles to systemic uptake. For example, the lining of the gastrointestinal tract comprises a thick wall of epithelial cells covered by a layer of polysaccharides and mucus. In this review, we will discuss the biology underlying intestinal uptake of protein-containing, biodegradable nanoparticles, review insulin delivery as the most accepted model for oral delivery of proteins, and present a variety of new material systems enabling novel approaches to oral protein delivery which we believe will bring to bear the next therapeutic advances in our field.

TNRC9 downregulates BRCA1 expression and promotes breast cancer aggressiveness.

Although the linkage between germline mutations of BRCA1 and hereditary breast/ovarian cancers is well established, recent evidence suggests that altered expression of wild-type BRCA1 might contribute to the sporadic forms of breast cancer. The breast cancer gene trinucleotide-repeat-containing 9 (TNRC9; TOX3) has been associated with disease susceptibility but its function is undetermined. Here, we report that TNRC9 is often amplified and overexpressed in breast cancer, particularly in advanced breast cancer. Gene amplification was associated with reduced disease-free and metastasis-free survival rates. Ectopic expression of TNRC9 increased breast cancer cell proliferation, migration, and survival after exposure to apoptotic stimuli. These phenotypes were associated with tumor progression in a mouse model of breast cancer. Gene expression profiling, protein analysis, and in silico assays of large datasets of breast and ovarian cancer samples suggested that TNRC9 and BRCA1 expression were inversely correlated. Notably, we found that TNRC9 bound to both the BRCA1 promoter and the cAMP-responsive element-binding protein (CREB) complex, a regulator of BRCA1 transcription. In support of this connection, expression of TNRC9 downregulated expression of BRCA1 by altering the methylation status of its promoter. Our studies unveil a function for TNRC9 in breast cancer that highlights a new paradigm in BRCA1 regulation.

Three-dimensional microfiber devices that mimic physiological environments to probe cell mechanics and signaling.

Many physiological systems are regulated by cells that alter their behavior in response to changes in their biochemical and mechanical environment. These cells experience this dynamic environment through an endogenous biomaterial matrix that transmits mechanical force and permits chemical exchange with the surrounding tissue. As a result, in vitro systems that mimic three-dimensional, in vivo cellular environments can enable experiments that reveal the nuanced interplay between biomechanics and physiology. Here we report the development of a minimal-profile, three-dimensional (MP3D) experimental microdevice that confines cells to a single focal plane, while allowing the precise application of mechanical displacement to cells and concomitant access to the cell membrane for perfusion with biochemical agonists. The MP3D device--an ordered microfiber scaffold erected on glass--provides a cellular environment that induces physiological cell morphologies. Small manipulations of the scaffold's microfibers allow attached cells to be mechanically probed. Due to the scaffold's minimal height profile, MP3D devices confine cells to a single focal plane, facilitating observation with conventional epifluorescent microscopy. When examining fibroblasts within MP3D devices, we observed robust cellular calcium responses to both a chemical stimulus as well as mechanical displacement of the cell membrane. The observed response differed significantly from previously reported, mechanically-induced calcium responses in the same cell type. Our findings demonstrate a key link between environment, cell morphology, mechanics, and intracellular signal transduction. We anticipate that this device will broadly impact research in fields including biomaterials, tissue engineering, and biophysics.

Enhanced cellular uptake and long-term retention of chitosan-modified iron-oxide nanoparticles for MRI-based cell tracking.

Tracking cells after therapeutic transplantation is imperative for evaluation of implanted cell fate and function. In this study, ultrasmall superparamagnetic iron oxide nanoparticles (USPIO NPs) were surface functionalized with water-soluble chitosan, a cationic polysaccharide that mediates enhanced endocytic uptake, endosomal escape into the cytosol, and subsequent long-term retention of nanoparticles. NP surface and chitosan were independently fluorescently labeled. Our NPs enable NP trafficking studies and determination of fate beyond uptake by fluorescence microscopy as well as tracking of labeled cells as localized regions of hypointensity in T(2)*-weighted magnetic resonance imaging (MRI) images. Adult rat neural stem cells (NSCs) were labeled with NPs, and assessment of NSC proliferation rates and differentiation potential revealed no significant differences between labeled and unlabeled NSCs. Significantly enhanced uptake of chitosan NPs in comparison to native NPs was confirmed by transmission electron microscopy, nuclear magnetic resonance (NMR) spectroscopy and in vitro cellular MRI at 11.7 Tesla. While only negligible fractions of native NPs enter cells, chitosan NPs appear within membranous vesicles within 2 hours of exposure. Additionally, chitosan-functionalized NPs escaped from membrane-bound vesicles within days, circumventing NP endo-lysosomal trafficking and exocytosis and hence enabling long-term tracking of labeled cells. Finally, our labeling strategy does not contain any NSC-specific reagents. To demonstrate general applicability across a variety of primary and immortalized cell types, embryonic mouse NSCs, mouse embryonic stem cells, HEK 293 kidney cells, and HeLa cervical cancer cells were additionally exposed to chitosan-USPIO NPs and exhibited similarly efficient loading as verified by NMR relaxometry. Our efficient and versatile labeling technology can support cell tracking with close to single cell resolution by MRI in vitro, for example, in complex tissue models not optically accessible by confocal or multi-photon fluorescence microscopy, and potentially in vivo, for example, in animal models of human disease or injury.

Direct and cell signaling-based, geometry-induced neuronal differentiation of neural stem cells.

Neural Stem Cells (NSCs) are multipotent precursors inhabiting the subventricular and hippocampal subgranular regions of the adult mammalian brain, able to self-renew and differentiate into neurons, astrocytes, and oligodendrocytes, the three primary neural cell types of the adult brain. NSC fate is influenced by the physical and chemical microenvironment experienced by the cell, both in vitro and in vivo. Towards characterizing the influence of topographical, geometric cues on NSC fate, we fabricated highly aligned, single- and double-layer polystyrene nanofiber meshes. Seeding of NSCs on laminin-coated fibers induces polarized NSC morphology and cellular elongation in the directions of fiber alignment, with cells extending membranous processes over hundreds of microns along the fiber surfaces. Additionally, these aligned fiber substrates promote neuronal lineage specification of NSCs with an efficiency of 82.3 ± 11.1% within days of seeding. Moreover, not only do cells on fibers yield neurons, but also neighboring cells in close proximity to those differentiating on aligned fibers, with an efficiency of 72.8 ± 9.7%. This neighboring, cell-induced differentiation occurs without cell-cell contact over millimetres away from the fibers, suggesting a paracrine signaling effect not previously reported for NSCs undergoing neurogenesis. In contrast, NSCs farther away from these fiber substrates nearly uniformly yield glia.