Stephan Moll, MD writes….
The pharmaceutical company Portola reported today (May 8th, 2013) without many details on the findings of their phase 2 human volunteer study of their anti-Xa anticoagulant antidote PRT4445 — ClinicalTrials.gov Identifier: NCT01758432 (study description here). In this study, healthy volunteers who had taken Eliquis (Apixaban) received the antidote. The study showed a “rapid and sustained and dose-related reversal of the anticoagulant activity of Eliquis” (thrombin generation and anti-factor Xa activity) and “no serious adverse events”.
PRT4445 is a recombinant molecule, structurally very similar to native factor Xa, but with some modifications that make it inactive as a clotting factor. It acts as a decoy for factor Xa inhibitor drugs, binding them. Once they are bound they are unable to bind to and inhibit native factor Xa. Thus, the native factor Xa becomes available to participate in the coagulation process and normal hemostasis is restored.
The full Portola report is here. The data of the study still need to be presented at a medical meeting and published. At this point all that can be concluded is that the drug is reported to have an ex vivo effect on coagulation tests. Whether it has any clinical efficacy in major bleeding associated with Eliquis or any of the other new oral anti-Xa anticoagulants (Xarelto=rivaroxaban; Edoxaban) has yet to be investigated.
Disclosure: I have consulted for Janssen, Boehringer-Ingelheim, and Daiichi.
Last updated: May 8th, 2013
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