Stroke Treatment With PAR-1 Agents to Decrease Hemorrhagic Transformation.

Ischemic stroke is the most widespread cause of disability and a leading cause of death in developed countries. To date, the most potent approved treatment for acute stroke is recanalization therapy with thrombolytic drugs such as tissue plasminogen activator (rt-PA or tPA) or endovascular mechanical thrombectomy. Although tPA and thrombectomy are widely available in the United States, it is currently estimated that only 10-20% of stroke patients get tPA treatment, in part due to restrictive selection criteria. Recently, however, tPA and thrombectomy selection criteria have loosened, potentially allowing more patients to qualify. The relatively low rate of treatment may also reflect the perceived risk of brain hemorrhage following treatment with tPA. In translational research and a single patient study, protease activated receptor 1 (PAR-1) targeted therapies given along with thrombolysis and thrombectomy appear to reduce hemorrhagic transformation after recanalization. Such adjuncts may likely enhance the availability of recanalization and encourage more physicians to use the recently expanded selection criteria for applying recanalization therapies. This narrative review discusses stroke therapies, the role of hemorrhagic transformation in producing poor outcomes, and presents the data suggesting that PAR-1 acting agents show promise for decreasing hemorrhagic transformation and improving outcomes.

3K3A-Activated Protein C Variant Does Not Interfere With the Plasma Clot Lysis Activity of Tenecteplase.

BACKGROUND AND PURPOSE: A recombinant engineered variant of APC (activated protein C), 3K3A-APC, lacks anticoagulant properties (<10%) while preserving APCs anti-inflammatory, anti-apoptotic, and neuroprotective functions and is very promising in clinical trials for ischemic stroke. Therapeutic intervention with single bolus administration of the third-generation tPA (tissue-type plasminogen activator), tenecteplase, is anticipated to be widely adopted for treatment of acute ischemic stroke. 3K3A-APC is well-tolerated in stroke patients dosed with alteplase, and in vitro studies show 3K3A-APC does not interfere with alteplase-induced clot lysis. The purpose of this in vitro study was to assess the influence of 3K3A-APC on tenecteplase-induced clot lysis. METHODS: Tenecteplase-mediated lysis of thrombin generated plasma clots of human normal pooled plasma was monitored in the presence of varying doses of 3K3A-APC. The effects on fibrinolysis by tenecteplase and alteplase were compared. RESULTS: The presence of 3K3A-APC shortened the time for clot lysis induced by tenecteplase at very low levels but not at higher therapeutic concentrations of tenecteplase. Comparisons of alteplase-mediated clot lysis to tenecteplase clot lysis showed that both thrombolytic agents behaved similarly in the presence of 3K3A-APC. CONCLUSIONS: These results indicate that 3K3A-APC does not interfere with tenecteplase's clot lysis function.

Final Results of the RHAPSODY Trial: A Multi-Center, Phase 2 Trial Using a Continual Reassessment Method to Determine the Safety and Tolerability of 3K3A-APC, A Recombinant Variant of Human Activated Protein C, in Combination with Tissue Plasminogen Activator, Mechanical Thrombectomy or both in Moderate to Severe Acute Ischemic Stroke.

OBJECTIVE: Agonism of protease-activated receptor (PAR) 1 by activated protein C (APC) provides neuro- and vasculoprotection in experimental neuroinjury models. The pleiotropic PAR1 agonist, 3K3A-APC, reduces neurological injury and promotes vascular integrity; 3K3A-APC proved safe in human volunteers. We performed a randomized, controlled, blinded trial to determine the maximally tolerated dose (MTD) of 3K3A-APC in ischemic stroke patients. METHODS: The NeuroNEXT trial, RHAPSODY, used a novel continual reassessment method to determine the MTD using tiers of 120, 240, 360, and 540 µg/kg of 3K3A-APC. After intravenous tissue plasminogen activator, intra-arterial mechanical thrombectomy, or both, patients were randomized to 1 of the 4 doses or placebo. Vasculoprotection was assessed as microbleed and intracranial hemorrhage (ICH) rates. RESULTS: Between January 2015 and July 2017, we treated 110 patients. Demographics resembled a typical stroke population. The MTD was the highest-dose 3K3A-APC tested, 540 µg/kg, with an estimated toxicity rate of 7%. There was no difference in prespecified ICH rates. In exploratory analyses, 3K3A-APC reduced ICH rates compared to placebo from 86.5% to 67.4% in the combined treatment arms (p = 0.046) and total hemorrhage volume from an average of 2.1 ± 5.8 ml in placebo to 0.8 ± 2.1 ml in the combined treatment arms (p = 0.066). INTERPRETATION: RHAPSODY is the first trial of a neuroprotectant for acute ischemic stroke in a trial design allowing thrombectomy, thrombolysis, or both. The MTD was 540 µg/kg for the PAR1 active cytoprotectant, 3K3A-APC. A trend toward lower hemorrhage rate in an exploratory analysis requires confirmation. CLINICAL TRIAL REGISTRATION: Clinical Trial Registration-URL: http://www.clinicaltrials.gov. Unique identifier: NCT02222714. ANN NEUROL 2019;85:125-136.

Selecting Patients for Intra-Arterial Therapy in the Context of a Clinical Trial for Neuroprotection.

BACKGROUND AND PURPOSE: The advent of intra-arterial neurothrombectomy (IAT) for acute ischemic stroke opens a potentially transformative opportunity to improve neuroprotection studies. Combining a putative neuroprotectant with recanalization could produce more powerful trials but could introduce heterogeneity and adverse event possibilities. We sought to demonstrate feasibility of IAT in neuroprotectant trials by defining IAT selection criteria for an ongoing neuroprotectant clinical trial. METHODS: The study drug, 3K3A-APC, is a pleiotropic cytoprotectant and may reduce thrombolysis-associated hemorrhage. The NeuroNEXT trial NN104 (RHAPSODY) is designed to establish a maximally tolerated dose of 3K3A-APC. Each trial site provided their IAT selection criteria. An expert panel reviewed site criteria and published evidence. Finally, the trial leadership designed IAT selection criteria. RESULTS: Derived selection criteria reflected consistency among the sites and comparability to published IAT trials. A protocol amendment allowing IAT (and relaxed age, National Institutes of Health Stroke Scale, and time limits) in the RHAPSODY trial was implemented on June 15, 2015. Recruitment before and after the amendment improved from 8 enrolled patients (601 screened, 1.3%) to 51 patients (821 screened, 6.2%; odds ratio [95% confidence limit] of 4.9 [2.3-10.4]; P<0.001). Gross recruitment was 0.11 patients per site month versus 0.43 patients per site per month, respectively, before and after the amendment. CONCLUSIONS: It is feasible to include IAT in a neuroprotectant trial for acute ischemic stroke. Criteria are presented for including such patients in a manner that is consistent with published evidence for IAT while still preserving the ability to test the role of the putative neuroprotectant. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT02222714.

Phase 1 safety, tolerability and pharmacokinetics of 3K3A-APC in healthy adult volunteers.

BACKGROUND AND PURPOSE: Activated Protein C (APC) stimulates multiple cytoprotective pathways via the protease activated receptor-1 (PAR-1) and promotes anticoagulation. 3K3A-APC was designed for preserved activity at PAR-1 with reduced anticoagulation. This Phase 1 trial characterized pharmacokinetics and anticoagulation effects of 3K3A-APC. METHODS: Subjects (n=64) were randomly assigned to receive 3K3A-APC (n=4) at 6, 30, 90, 180, 360, 540 or 720 µg/kg or placebo (n=6) and were observed for 24 hr. After safety review additional subjects received drug every 12 hr for 5 doses (n=6 per group) at 90, 180, 360, or 540 µg/kg or placebo (n=8) and were observed for 24 hr. RESULTS: All subjects returned for safety assessments at 72 hours and 15 days. We found few adverse events in all groups. Systolic blood pressure increased in both active and placebo groups. Moderately severe headache, nausea and vomiting were reported in one of two subjects treated with 720 µg/kg so 540 µg/kg was considered the highest tolerated dose. Mean plasma concentrations increased in proportion to dose. Clearance ranged from 11,693 ± 807 to 18,701 ± 4,797 mL/hr, volume of distribution ranged from 4,873±828 to 6,971 ± 1,169 mL, and elimination half-life ranged from 0.211 ± 0.097 to 0.294 ± 0.054 hours. Elevations in aPTT were minimal. CONCLUSIONS: 3K3A-APC was well tolerated at multiple doses as high as 540 µg/kg. These results should be confirmed in stroke patients with relevant co-morbidities. Clinical Trial Registration-URL: http://www.clinicaltrials.gov. Unique identifier: NCT01660230.

Preclinical safety and pharmacokinetic profile of 3K3A-APC, a novel, modified activated protein C for ischemic stroke.

Activated protein C (APC), a protease with anticoagulant and cytoprotective activities, protects neurons and cerebrovascular endothelium from ischemic injury. A recombinant APC, drotrecogin alfa (activated) (DrotAA) (Xigris®), was approved by the Food and Drug Administration for the treatment of sepsis; however, serious bleeding was a dose-limiting side effect. A modified APC, containing 405 amino acid residues, 3K3A-APC, was designed to possess significantly reduced anticoagulant activity ( < 10 %) while maintaining full cytoprotective properties. The preclinical safety assessment of 3K3A-APC was conducted to support initiation of ischemic stroke clinical trials.The safety and toxicokinetics of 3K3A-APC were studied in CD-1 mice and cynomolgus monkeys. Multiple-dose (14-day), intravenous GLP toxicology assessed toxicity, histopathology, immunogenicity, and toxicokinetics.Dose-related increases in plasma total 3K3A-APC were observed in mice and monkeys with no evidence of accumulation over 14 days. The elimination T(1/2) in monkeys was 1 hour. 3K3A-APC was well tolerated in mice and monkeys, and no signs of 3K3A-APC toxicity were identified in mice or monkeys at any time. Additionally,wild-type APC (DrotAA) was studied to obtain comparative anticoagulant data using clotting assays. Anticoagulant activity of 3K3A-APC was observed in monkeys at doses of 1 and 5 mg/kg/day .In contrast, DrotAA showed prolongation of clotting assays in monkeys at doses 1/10(th) of those showing effects with 3K3A-APC. Based upon the anticoagulant profiles, the risk for APC-induced bleeding in clinical trials of 3K3A-APC is greatly reduced relative to wild type APC which makes this new drug a feasible therapy for ischemic stroke patients.

2,5-Diaminopyrimidines and 3,5-disubstituted azapurines as inhibitors of glycogen synthase kinase-3 (GSK-3).

The discovery of two classes of pyrimidine-based inhibitors of GSK-3 is described. Optimization of these series led to inhibitors with IC(50)<10nM and >100-fold selectivity over Aurora A kinase. A proposed binding mode of 21b is presented. One compound (33) of the pyrimidine series showed promising pharmacokinetic parameters.