Index Ventures, working with GlaxoSmithKline and Johnson & Johnson via an early-stage biotech fund, said on Monday it was investing $11 million in XO1, a new company set up to develop the experimental medicine.
Called ichorcumab, the new drug is still miles from reaching the market - clinical trials are only slated to start within the next two years - but the product may create a stir in a commercially important field, given its unusual properties.
It was created by scientists at the University of Cambridge and Addenbrooke's Hospital following the observation of a patient in her 50s whose blood appeared unable to clot but who had no major bleeding problems after a head injury in 2008.
The researchers pinpointed her unusual response to a unique antibody, which they went on to synthesise.
Currently, anticoagulants are used to reduce the risk of heart attacks and strokes, but doctors have to weigh up carefully their benefits against the danger of triggering uncontrolled bleeding.
"This antibody can deliver a high degree of anticoagulation without increased bleeding; we've never seen that before," said Jim Huntingdon, a professor at the Cambridge Institute of Medical and one of the scientists behind the project.
Warfarin has been a mainstay of anticoagulation therapy for many years. More recently new drugs have been launched, including Boehringer Ingelheim's Pradaxa, Bayer and J&J's Xarelto, and Pfizer and Bristol-Myers Squibb's Eliquis.
The $11 million start-up cash for XO1 comes from a $200 million life sciences fund launched last year by Index in an unusual collaboration with GSK and J&J. The fund aims to invest in companies with just one or two projects - a so-called "asset-centric" approach.
Under the three-way deal, the venture capital firm controls all investment decisions and the two drugmakers have no preferential rights to acquire any new drugs, although they do get a useful inside view should they wish to compete for assets.
(Reporting by Ben Hirschler; editing by Keiron Henderson)