ICYMI: SerpinPC Earns Orphan Drug Designation for Hemophilia B


Sometimes, it can be difficult to incentivize researchers and drug developers to focus on solutions for those with rare conditions. The FDA created the Orphan Drug Act to overcome these barriers and spur drug development within this realm. Orphan Drug designation is granted to drugs or biologics intended to treat, diagnose, or prevent rare conditions. These are those affecting fewer than 200,000 Americans. As a benefit, drug developers receive incentives such as fee waivers, tax credits, and seven years of market exclusivity upon product approval. According to a mid-September 2022 news release from Centessa Pharmaceuticals, the FDA recently granted Orphan Drug designation to the company’s product SerpinPC for hemophilia B. 

On its website, Centessa Pharmaceuticals describes SerpinPC as:

a specific inhibitor of activated protein C (APC)…[that] has been observed to be well-tolerated in the clinical setting, associated with promising reductions in bleeding rates, and has PK suitable for infrequent subcutaneous dosing without the need for factor replacement. SerpinPC has human genetic target validation and established proof of concept Phase 2a clinical data.

This biologic drug hopes to rebalance coagulation in those with hemophilia. The clinical data highlighted how, at its highest administered doses, SerpinPC was able to reduce median Annualized Bleeding Rate (ABR) by 88% for all bleeds and 94% in spontaneous joint bleeds. Although the Orphan Drug designation was granted for hemophilia B, SerpinPC is being developed for both hemophilia A and B. 

What is Hemophilia B?

There are two basic forms of hemophilia: A and B. The former (A) is the more common form. Hemophilia B is a rare inherited bleeding disorder characterized by factor IX deficiency. F9 gene mutations cause hemophilia B. Ultimately, the factor IX deficiency prevents the body from adequately clotting blood, causing prolonged bleeding after surgery, accidents, or even common procedures. Additionally, some individuals may experience spontaneous bleeding. Hemophilia B is a variable condition; it varies in severity and symptoms from person-to-person. Symptoms can (but do not always) include:

  • Easy bruising
  • Urinary and gastrointestinal tract bleeding
  • Bloody stool
  • Hematuria (blood in the urine)
  • Joint pain, swelling, and redness (if joint bleeds occur)
  • Restricted movement (if joint bleeds occur)
  • Stiff neck (if brain bleed occurs)
  • Vomiting (if brain bleed occurs)
  • Seizures (if brain bleed occurs)
  • Extended bleeds from cuts, abrasions, surgery, etc. 
  • Nosebleeds
  • Heavy menstrual periods

Brain bleeds can be fatal if left untreated. If experiencing these more severe symptoms, please seek emergency services as soon as possible.

Jessica Lynn

Jessica Lynn

Jessica Lynn has an educational background in writing and marketing. She firmly believes in the power of writing in amplifying voices, and looks forward to doing so for the rare disease community.

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