Clotting disorders can be treated by infusing patients with clotting proteins they lack, or with drugs that replace the function of these proteins. Gene therapies may soon become another option. Hemophilia A and B are perhaps the best-known clotting diseases, and both have benefited from decades of research while rarer bleeding disorders continue to lack treatment options, according to Benny Sorensen, CEO of Hemab Therapeutics.

Hemab is already in the clinic with a lead program in development for a rare clotting disorder that has no approved therapies. Now the biotech startup, which splits its operations between Boston and Copenhagen, Denmark, has $135 million to support that drug candidate as well as a pipeline of other programs aiming to bring innovation to underserved bleeding and thrombotic disorders.

“That’s the vision, that’s the mission of Hemab—to leapfrog the treatment options into the 21st century,” Sorensen said.

The Series B round of financing announced Tuesday was led by Access Biotechnology.

Lead Hemab drug candidate HMB-001 is in development to treat Glanzmann thrombasthenia, an inherited disorder in which a genetic abnormality leads to platelets that cannot properly perform their clotting functions. Those who have the disorder tend to bruise and bleed easily. Even if these patients have platelet numbers in the range that’s considered normal, it takes them longer to stop bleeding. Standard treatment is a blood platelet transfusion, which requires patients to make regular visits to a transfusion center for the rest of their lives. One potential problem is that patients may develop antibodies against the transfused platelets, which limits their effectiveness.

With HMB-001, Hemab aims to use blood clotting proteins already in the body to help improve platelet function. The drug is a bispecific antibody with one part designed to bind to and stabilize a protein called factor VII (FVIIa) and another part that binds to a target on activated platelets called TLT-1. By recruiting FVIIa to the surface of platelets, the drug is intended to facilitate clotting and also avoid clotting activity when there is no tissue damage. Hemab is developing this drug to prevent bleeding episodes in Glanzmann patients.

Sorensen’s experience includes senior roles at Alnylam Pharmaceuticals and Codiak Biosciences, both of which are working with new drug modalities. Alnylam was the first company to win approval of a medicine that works by leveraging a mechanism called RNA interference. Codiak’s still experimental approach uses exosomes, tiny vesicles that shuttle molecules between cells. By contrast, Hemab isn’t reinventing the wheel with its bleeding disorder drugs. Sorensen said the company is pursuing known targets by using antibodies, an approach validated in many diseases, including blood disorders. For example, Roche hemophilia A drug Hemlibra showed that bispecific antibodies can work to treat clotting disorders.

Hemab’s scientists have deep expertise in clotting biology, with knowledge about every protein involved in coagulation and how to manipulate them, Sorensen said. What Hemab is doing is translating that knowledge into new medicines. The company rationally designs antibodies that can generate a desired mechanism of action. Depending on the disease, the company’s approach could involve a bispecific antibody or a monoclonal antibody.

In preclinical research, Hemab reported that HMB-001 led to the formation of fibrin on platelets. Fibrin is a protein that is produced in response to bleeding and is a component of blood clots. The data also showed the accumulation of FVIIa. A Phase 1/2 study evaluating HMB-001 dosed its first patient last month. Preliminary data are expected in the second half of this year.

HMB-001 was licensed from Novo Nordisk. The rest of the pipeline is based on Hemab’s internal research. The most-advanced of the internally developed programs, HMB-VWF, is in development for von Willebrand disease, which is characterized by low levels of the von Willebrand clotting protein. Three more preclinical programs are in the pipeline. Sorensen said Hemab’s goal is to have its five programs in the clinic by 2025. Those drug candidates all address rare conditions. Sorensen left the door open to addressing more prevalent clotting disorders, but he added that Hemab is not going to pursue hemophilia and is instead focused on diseases with unmet need.

Hemab closed a $55 million Series A round of funding in 2021. The latest financing adds new investors Deep Track Capital, Avoro Capital, Invus, Rock Springs Capital, and Maj Invest Equity. They were joined by earlier investors Novo Holdings, RA Capital Management, and HealthCap. Sorensen acknowledged the challenging economic environment but he said Hemab was able to generate strong investor interest.

“If you have a recognized unmet need, you‘ve got strong science, the medicines are important and you have an accomplished team, that’s the recipe for being successful,” he said.

Photo: virusowy, Getty Images