Abstract 10: Randomized, Double-Blind, Placebo-Controlled Single Ascending Dose Pharmacokinetic and Pharmacodynamic Study of PRT064445, a Universal Antidote for Factor Xa Inhibitors
Bibliographic record
Abstract
Background Direct factor Xa inhibitors [fXaI] have superior anticoagulant efficacy and/or safety relative to warfarin and LMWH but are limited by lack of a specific antidote to reverse anticoagulation during episodes of serious bleeding or before surgery. PRT064445 [PRT] is a modified, human recombinant fXa that is catalytically inactive but retains high-affinity binding to direct fXaI and heparin- antithrombin III complexes. It competes with native fXa for fXaI drugs, thus reversing direct and indirect fXaI-mediated anticoagulation. Methods In this phase I, first-in-man double-blind study, 32 healthy volunteers were randomized (6:2) within dosing cohorts to a single IV bolus of PRT (30 mg, 90 mg, 300 mg, or 600 mg) or placebo and followed for 28 days. Anti-fXa activity was assayed in vitro by adding exogenous rivaroxaban (50 ng/mL) to subject plasma samples. Results The terminal t1/2 was ~6 hours. AUC and Cmax increased disproportionately relative to dose. In the presence of PRT, thrombin generation and anti-fXa activity of rivaroxaban ( Figure ) were reversed in a dose-dependent manner. There were no thrombotic AEs or deaths. There was 1 serious AE (pneumonia) and 3 non-serious infusion-related reactions without anaphylaxis [90 mg (2) and placebo (1)]. One unplanned pregnancy occurred ~10 days post-treatment, followed shortly by a spontaneous abortion. Prothrombin fragment 1 + 2, thrombin-antithrombin complex, and D-dimer transiently increased with dose; other coagulation parameters including PT, aPTT, ACT and platelet activity were unchanged. Conclusions PRT is a promising universal antidote for fXaI. A Phase 2 trial evaluating PRT reversal of several fXaI is ongoing.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.002 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.005 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.002 | 0.002 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.003 | 0.004 |
| Insufficient payload (model declined to judge) | 0.013 | 0.003 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".