FDA Grants Fast Track Designation to Two Therapies for Hematological Disorders

Rare Daily Staff

The U.S. Food and Drug Administration granted Fast Track designation to two treatments for rare hematological diseases: Protagonist Therapeutics’ PTG-300 for the treatment of polycythemia vera, and Catalyst Biosciences’ Marzeptacog alfa, an engineered coagulation Factor VIIa for the treatment of episodic bleeding in subjects with Hemophilia A or B with inhibitors.

The FDA Fast Track program is designed to facilitate and expedite the development and review of drug candidates that have demonstrated the potential to address an unmet medical need in treating serious diseases or conditions. A drug candidate with Fast Track designation is eligible for greater access to the FDA as well as a priority review and rolling review of the marketing application. 

Polycythemia vera is a rare myeloproliferative disease characterized by the excessive production of red blood cells. Well-established treatment guidelines focus on maintaining hematocrit levels continuously below 45 percent to reduce the risk of thrombotic events, but they are unable to maintain hematocrit to below the 45 percent target for many patients and may be associated with serious side effects. There are an estimated 100,000 patients with polycythemia vera in the United States and approximately 100,000 patients in major EU countries.

PTG-300 is an injectable synthetic peptide mimetic of the natural hormone hepcidin that has demonstrated the ability to dramatically decrease the requirement for phlebotomy in an ongoing phase 2 study in polycythemia vera patients. The FDA previously granted orphan drug designation to PTG-300 for the treatment of polycythemia vera.

“Fast Track designation reflects the potential for PTG-300 to improve upon the treatments that are currently available for patients with polycythemia vera, and provides opportunities to substantially accelerate clinical development,” said Dinesh Patel, president and CEO of Protagonist. “We continue to enroll and treat patients in our ongoing phase 2 study, with complete enrollment expected in mid-2021 and look forward to working closely with the FDA to discuss and finalize a pivotal program in the first half of 2021.”

Catalyst Biosciences received FDA Fast Track designation for Marzeptacog alfa (activated) – or MarzAA, the company’s subcutaneously administered next-generation engineered coagulation Factor VIIa for the treatment of episodic bleeding in subjects with Hemophilia A or B with inhibitors, which will enter a pivotal phase 3 study this month.

People living with hemophilia lack sufficient functioning factor VIII or factor IX protein to help their blood clot and are at risk for painful and/or potentially life-threatening bleeds from even modest injuries.

The phase 3 CRIMSON 1 study is an open-label, global, multi-center, randomized, cross-over study, designed to evaluate the safety and efficacy of MarzAA for on-demand treatment of spontaneous or traumatic bleeding episodes, in adolescents and adults with congenital Hemophilia A or B with inhibitors, compared to the standard of care. The study will enroll approximately 60 subjects to treat 244 eligible bleeding episodes with each treatment. The primary endpoint for the trial is the percentage of treated bleeds resulting in effective hemostasis at the 24-hour time point. The objective of the trial is to demonstrate non-inferiority of MarzAA compared with standard of care.

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

Photo: Nassim Usman, president and CEO of Catalyst