RNA aptamers as reversible antagonists of coagulation factor IXa


Many therapeutic agents are associated with adverse effects in patients. Anticoagulants can engender acute complications such as significant bleeding that increases patient morbidity and mortality1. Antidote control provides the safest means to regulate drug action. For this reason, despite its known limitations and toxicities, heparin use remains high because it is the only anticoagulant that can be controlled by an antidote, the polypeptide protamine2,3,4. To date, no generalizable strategy for developing drug–antidote pairs has been described. We investigated whether drug–antidote pairs could be rationally designed by taking advantage of properties inherent to nucleic acids to make antidote-controlled anticoagulant agents. Here we show that protein-binding oligonucleotides (aptamers) against coagulation factor IXa are potent anticoagulants. We also show that oligonucleotides complementary to these aptamers can act as antidotes capable of efficiently reversing the activity of these new anticoagulants in plasma from healthy volunteers and from patients who cannot tolerate heparin5. This generalizable strategy for rationally designing a drug–antidote pair thus opens up the way for developing safer regulatable therapeutics.

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Figure 1: Sequences and secondary structure of aptamers isolated against FIXa.
Figure 2: Inhibition of FIXa function by aptamers 9.3t and Peg-9.3t.
Figure 3: Antidote oligonucleotides to aptamer 9.3t.
Figure 4: Properties of antidote oligonucleotide 5-2.
Figure 5: Antidote-controlled anticoagulation of plasma from patients with HIT.


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We thank R. Califf and R. Harrington for their insight into the need for antidote-controlled anticoagulant and antithrombotic agents. This work was supported by grants from the American Heart Association to C.P.R. and the National Institutes of Health to B.A.S, T.L.O. and D.M.

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Correspondence to Christopher P. Rusconi or Bruce A. Sullenger.

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Competing interests

C.P.R., E.S., J.L., T.L.O. and B.A.S. are employed by the Duke University Medical Center, which has filed two patent applications on work described in this Letter.

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Rusconi, C., Scardino, E., Layzer, J. et al. RNA aptamers as reversible antagonists of coagulation factor IXa. Nature 419, 90–94 (2002). https://doi.org/10.1038/nature00963

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