DalcA Effective and Safe as Hemophilia B Injection Treatment, Study Suggests

Data from a completed Phase 2b trial indicate that dalcinonacog alfa (DalcA) is an effective and safe therapy to prevent bleeding in people with severe hemophilia B.

Final results from this open-label study in six patients are expected by June.

“We are pleased to have successfully completed the DalcA Phase 2b trial during this challenging pandemic and remain on track to report final results later this quarter,” Nassim Usman, PhD, the president and CEO of Catalyst Biosciences, the treatment’s developers, said in a press release.

Hemophilia B is caused by a missing or defective factor IX (FIX), a blood clotting protein. DalcA (previously known as CB2679d) is a lab-made version of FIX intended to be used as a prophylactic (preventative) treatment of bleeding episodes.

DalcA can be administered via a subcutaneous (under-the-skin) injection. This is generally considered less invasive than intravenous (directly-into-the-bloodstream) injection, which is how many other FIX products are administered.

Prior results of a small Phase 1/2 study (NCT03186677) showed that DalcA was 22 times more potent and stayed in the body longer than Pfizer‘s BeneFIX, also an engineered (recombinant) form of FIX and used as replacement therapy for hemophilia B.

In the Phase 2b trial (NCT03995784), six men with severe hemophilia B received DalcA in one intravenous (directly into the bloodstream) loading dose of 50 international units (IU)/kg, followed by daily subcutaneous injections of 100 IU/kg for 28 days. A five-day washout period included daily measures of the treatment’s safety and pharmacological profile. The study, at a single site in South Africa, was open-label, meaning it had no placebo group.

Its primary goal was to assess the required DalcA dose to increase steady-state FIX activity levels above 12%. The trial was also evaluated DalcA’s safety, tolerability, immunogenicity — whether it induces an immune response — as well as how it affects (pharmacokinetics) and is affected by the body (pharmacodynamics).

Early data presented at this year’s 13th Annual Congress of European Association for Haemophilia and Allied Disorders, in the Netherlands, showed that treatment with DalcA achieved effective prophylaxis. Specifically, no bleeds were observed and steady-state FIX activity up to 27% was seen after 14 days. Two participants dropped out on day seven.

Treatment was well-tolerated, with two adverse reactions reported — an injection site reaction and one hematoma (localized bleeding outside of a blood vessel). Both events were moderate in severity and resolved without further complications. Researchers found no evidence of an immune response against DalcA, which could have limited the therapy’s effectiveness.

DalcA’s half-life — the time it takes for the concentration of a compound within the body to drop by half —ranged from 70 to 112 hours, suggesting it could allow for less frequent dosing than existing alternatives.

These data “clearly demonstrated the potential for DalcA to significantly change the treatment paradigm in hemophilia B; we look forward to continuing its development,” Usman said.