Cambridge spin-out XO1, which is developing anticoagulants that could have a sizeable impact on preventing heart attacks and strokes, has received $11m from Index Ventures.

The life science investor was the sole participant in the $11m round, made through Index’s $200m Life Sciences fund launched last year, and represents the company’s largest investment in a life science company to date.

The funding will be used to develop ichorcumab, an antibody created by researchers at the University of Cambridge and affiliated hospital Addenbrooke. Originally discovered naturally occurring in a patient who arrived at Addenbrooke’s accident and emergency department with a head injury and anticoagulation consistent with severe haemophilia, what was initially thought to be a fatal injury stopped bleeding normally.

Anticoagulants are currently used to treat thrombosis, a major cause of heart attacks and strokes, but are inhibited by bleeding side-effects they cause. Therefore, an anticoagulant that does not cause bleeding, such as ichorcumab, would have serious medical potential.

David Grainger, venture partner at Index and interim chief executive of XO1, said: “This is the most exciting drug candidate I have seen in twenty years in the industry. It has the potential to save millions of lives.”