John M. Maraganore

Importance to Hirudotherapy

John Maraganore is the most commercially-impactful figure to have built a career on hirudin chemistry. While at Biogen in the late 1980s, Maraganore reasoned that the 65-amino-acid full-length hirudin molecule, while extraordinarily potent, had two practical limitations for clinical use: it was difficult to produce recombinantly at scale, and its very tight binding to thrombin made dose reversibility difficult (a problem if patients experienced procedural bleeding). His solution was to extract the two thrombin-binding 'pharmacophores' of hirudin — the N-terminal active-site occupier and the C-terminal exosite-I binder — and link them with a short flexible glycine-glycine spacer, producing a 20-amino-acid synthetic peptide that bound thrombin reversibly with sub-nanomolar affinity but with a plasma half-life of 25 minutes rather than hirudin's 60-90 minutes. The resulting compound, originally designated Hirulog-8, became bivalirudin (Angiomax) when Maraganore co-founded The Medicines Company in 1996 to develop it. The drug's FDA approval in December 2000 made it the third FDA-approved direct thrombin inhibitor (after Refludan 1998 and Iprivask 2003). Its critical practical advantage over Refludan was the reversible binding kinetics: in patients undergoing percutaneous coronary intervention, if procedural bleeding occurred, bivalirudin levels declined rapidly enough to allow safe management. This kinetic profile made bivalirudin the preferred DTI for PCI, and the 2008 HORIZONS-AMI trial in 3,602 patients showed a 25% reduction in 30-day major bleeding compared with heparin + GP IIb/IIIa inhibitor — a result that drove bivalirudin's adoption as a standard of care in U.S. and European cath labs. The broader scientific impact of Maraganore's design — the bivalent inhibitor concept — extended far beyond bivalirudin. Argatroban, dabigatran, and several Factor Xa inhibitors (rivaroxaban, apixaban) all reflect downstream applications of the lesson that a bipartite enzyme-binding strategy can be condensed into a small synthetic molecule while preserving extraordinary potency. ASH considers Maraganore the most successful commercial translator of hirudotherapy science.