Aptamers are synthetic macromolecules that can adopt a unique three-dimensional shape and bind specifically and tightly to a target molecule.

Regado’s aptamer-based therapeutics are identified using a proprietary in vitro selection process known as SELEX (Systematic Evolution of Ligands by EXponential enrichment), which the Company in-licensed from Archemix Corporation.  In the SELEX process, a vast library of oligonucleotide sequences are incubated with a specific target protein and nucleic acid aptamers with the optimal structural and binding properties are isolated.  Aptamers have been discovered that can bind to essentially every class of therapeutic protein target.


The REG 1 anticoagulation system for PCI

(click video to view)

Once elucidated, an aptamer’s nucleotide sequence can be used to design an active control agent in the form of an oligonucelotide complementary to the nucleotide sequence of the aptamer, as discovered by Drs. Bruce Sullenger and Chris Rusconi of Duke University in the early 2000s.  An aptamer and its active control agent bind via nucleotide base pairing, triggering a structural change in the aptamer that causes its release from the target protein, negating the aptamer’s therapeutic effect.  Based upon the dose of active control agent administered, the activity of an aptamer can be fully neutralized, or titrated to intermediate levels in a tightly controlled manner.

Pioneering research on this approach to modulating the therapeutic activity of nucleic acid aptamers was published in Nature in September 2002, and Regado subsequently licensed the technology from Duke University.  By combining this technology with the SELEX discovery process, Regado has created a powerful platform for the discovery of aptamer control agent systems.


The REG1 Anticoagulant System is a two-component system consisting of an aptamer-based anticoagulant and its complementary active control agent.

The REG1 anticoagulant component, pegnivacogin (aka RB006), is a single-stranded, nucleic acid aptamer. RB006 selectively and potently binds to blood coagulation Factor IXa, inhibiting its activity and preventing blood clot formation. The active control agent, anivamersen (aka RB007), consists of a nucleotide sequence complementary to RB006. Binding of RB007 to RB006 releases RB006 from Factor IXa, causing the predictable and rapid reversal of its anticoagulant effect and allowing the patient’s blood to return to normal. Because binding of RB007 to RB006 is energetically favored and irreversible, reversal of the anticoagulant activity of RB006 by RB007 is sustained.

By adjusting the dose of RB007, physicians can reverse partially or completely the activity of RB006, titrating the anticoagulant effect based on each patient’s individual needs in each clinical setting. For this reason, Regado believes REG1 has the potential to be the anticoagulant therapy of choice from the emergency room to the operating room.

REG1 Mechanism of Action:

Coagulation proceeds unimpeded and clotting proceeds   RB006 selectively inhibits Factor IXa and clotting cannot proceed   RB007 binds to RB006; the resulting complex is incapable of inhibiting Factor IXa and clotting cascade resumes