MarzAA on FDA Fast Track to Treat Hemophilia A or B With Inhibitors

The U.S. Food and Drug Administration (FDA) has granted fast track designation to marzeptacog alfa activated (MarzAA), a lab-made version of clotting factor VIIa for the subcutaneous (under-the-skin) treatment of episodic bleeds in hemophilia A and B patients with inhibitors.

MarzAA, developed by Catalyst Biosciences, will enter a pivotal Phase 3 trial, dubbed CRIMSON-1 (NCT04489537) later this month. This trial is currently enrolling at a site in Tbilisi, Georgia.

“We believe the FDA Fast Track Designation validates MarzAA’s potential to improve patient care,” Nassim Usman, PhD, president and CEO of Catalyst, said in a press release. “As the only [under-the skin] delivered therapy in development for on-demand treatment of bleeding events, MarzAA is uniquely positioned to become an important addition to the treatment landscape.”

Fast track designation is intended to speed clinical development and regulatory review of potential medications for serious medical conditions with unmet medical needs. Catalyst will have greater access to the FDA during development and is eligible for priority and rolling reviews of its potential marketing application for MarzAA.

MarzAA is designed specifically to prevent acute bleeds in hemophilia patients with inhibitors. It’s being developed as an alternative to intravenous (into-the-vein) approaches that require technical expertise and are often associated with pain, leading to prolonged bleeding and accumulation of blood in bleeding sites.

The company presented its design for the CRIMSON-1 study at the virtual 62nd American Society of Hematology Annual Meeting & Exposition this week.

The trial will compare the safety and efficacy of MarzAA to standard care for on-demand treatment of spontaneous or traumatic bleeding episodes. Investigators seek approximately 60 participants, ages 12 and older, across 54 sites in 19 countries. Patients will self-administer MarzAA at 60 micrograms/kg in up to three doses at three-hour intervals, as needed to control bleeding.

To be eligible, participants must have an annualized bleeding rate of at least eight and be unresponsive to or intolerant of standard replacement therapy. Adults will be randomly assigned to treatment of approximately five bleeds with MarzAA and an additional five bleeds with standard care, in either order with a washout period to assess anti-MarzAA antibodies, for a total of nearly 244 bleeds given each treatment. In turn, younger patients will be enrolled after a positive safety assessment of 30 bleeds treated with MarzAA.

The trial’s goal is to show that MarzAA is not inferior to standard care.

Its primary measurement of efficacy is the percentage of effectively controlled bleeds at 24 hours after an initial dose. Secondary goals include the time it takes to stop bleeding after a dose, the percentage of effectively controlled bleeds at certain fixed timepoints, the percentage of treated bleeds that remain controlled at 48 hours post-dosing, and the use and amount of rescue therapy.

Safety measurements include the occurrence and severity of side effects, blood clots that block blood flow, and binding and/or neutralizing anti-MarzAA antibodies.

Also, patients will rate their satisfaction with the treatment via the Treatment Satisfaction Questionnaire for Medicine-9, their pain using the visual analog scale, and the time it took them to self-administer the treatment.

Treatment will continue until at least 80% of patients have had a minimum of three bleeds treated with MarzAA and standard care.

Results of a Phase 1 study (NCT04072237) showed that MarzAA was well-tolerated and quickly reached and maintained the levels needed to stop ongoing bleeding in men with hemophilia A or B.

In addition, a Phase 2/3 trial (NCT03407651) of MarzAA as a preventive treatment showed that daily use safely reduced the number of bleeds per year in men with hemophilia A or B with inhibitors and reduced the proportion of days they experienced bleeding.