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2619 Serpin-PC in Persons with Severe Hemophilia (PwH): Updated Results from a Multicenter Multi-Part, First-in-Human Study

Program: Oral and Poster Abstracts
Session: 322. Disorders of Coagulation or Fibrinolysis: Clinical and Epidemiological: Poster II
Sunday, December 10, 2023, 6:00 PM-8:00 PM

Trevor Baglin1*, James A. Huntington, PhD2, Annelize Koch, MD3*, Irina Mocanu, MD4* and Levani Makhaldiani, MD5*

1ApcinteX Ltd (a subsidiary of Centessa Pharmaceuticals plc), Boston, MA
2Cambridge Institute for Medical Research University of Cambridge, Cambridge, GBR
3Simbec-Orion Clinical Pharmacology, Merthyr Tydfil, United Kingdom
4Institute of Oncology, Arensia Exploratory Medicine, Chisinau, Moldova, The Republic of
5Arensia Exploratory Medicine, Tbilisi, Georgia


SerpinPC is an investigational serine protease inhibitor (SERPIN) engineered to specifically inhibit Activated Protein C (APC). The previously presented data from the completed parts of AP-0101 showed that administration of SerpinPC reduced bleeding in persons with severe hemophilia with no observations of unexplained chronic elevation in D-dimer. We will now present all results up to the end of Part 5 by which time we anticipate the median continuous exposure will be more than 3 years.


AP-0101 is an ongoing first-in-human open-label multicenter study utilizing an adaptive design to investigate the safety, tolerability, pharmacokinetics and efficacy of SerpinPC in subjects with severe hemophilia A and B.

Part 1a was a Single Ascending Dose Study of SerpinPC in 15 healthy male volunteers and 12 males with severe hemophilia.

Part 2 enrolled 23 males with severe hemophilia (19 hemophilia A and 4 hemophilia B), who were not on replacement factor prophylaxis, to receive SerpinPC at 0.3, 0.6 or 1.2 mg/kg, administered as a subcutaneous (SC) injection once every 4 weeks over a 24-week period (6 total doses).

In Part 3, subjects who completed Part 2 received a flat dose of 60 mg of SerpinPC once every 4 weeks for 48 weeks.

Part 4 was a further extension in which subjects who completed Part 3 received 1.2 mg/kg of SerpinPC once every 2 weeks for 24 weeks.

Part 5 was a further extension in which subjects who completed Part 4 continued to receive 1.2 mg/kg of SerpinPC once every 2 weeks for 52 weeks.


Annualized bleed rates, safety and tolerability for Part 5 will be available and a complete summary of all results to the end of Part 5 will be presented, including available pharmacokinetic and anti-drug antibody data.

Disclosures: Baglin: Centessa Pharmaceuticals Plc: Current Employment, Current equity holder in publicly-traded company, Current holder of stock options in a privately-held company. Huntington: Centessa Pharmaceuticals Plc: Consultancy, Current equity holder in publicly-traded company, Ended employment in the past 24 months.

*signifies non-member of ASH