Bayer-Ionis' anti-thrombotic med doesn't increase bleeding in phase 2, setting stage for a new type of anticoagulant

Patients with kidney disease taking Ionis Pharmaceuticals and Bayer’s anti-thrombotic therapy did not experience an increase in major bleeding events as compared to those taking placebo, meaning patients may someday have a new anticoagulant option that does not come with a risk of bleeding.

Fesomersen is being tested in patients with end-stage renal disease on hemodialysis in the Phase 2b RE-THINC ESRD study. The main goal was to show that the therapy did not increase the incidence of major bleeding events as well as a measure of clinically relevant non-major bleeding as compared to placebo.

The therapy met the main goal of the study, Ionis said in a Thursday press release. It also reduced Factor XI activity levels, a protein found in the liver involved in the coagulation pathway. Patients in the mid-stage trial were examined over 48 weeks. Fesomersen was found to be safe and well-tolerated, Ionis said.

Fesomersen is an antisense medicine being developed to reduce the production of Factor XI, which at high levels increases the risk of blood clot formation and therefore the risk of heart attacks and strokes. Patients with renal failure are at high risk for these events; in fact, the risk of stroke is five to 30 times higher in those with chronic kidney disease—especially those receiving dialysis.

Anticoagulants have long been used to prevent blood clots, but they can increase the risk of bleeding, according to Ionis’ Sanjay Bhanot, M.D., Ph.D., senior vice president, chief medical officer and metabolic and liver franchise leader. Fesomersen could therefore provide a less risky option for cardiovascular and renal disease patients.

The full details of the study were not offered, but both Bayer and Ionis promised in separate releases to publish further results at an upcoming medical meeting. Previous studies have shown that fesomersen, previously known as IONIS-FXI-LRx, inhibited Factor XI activity and was associated with a reduction in clotting events and no increase in major bleeding events. The latest phase 2b data backs that up.

Bayer licensed fesomersen from Ionis way back in 2015, offering $155 million in near-term payments including $55 million for advancement of the therapy into phase 2. Ionis noted a $75 million payment from Bayer in 2017 when the therapy advanced into phase 2b. At that point, Bayer took over further clinical development and has been in charge of the RE-THINC ESRD study.