CLPH-511 is prepared from a pool of irradiated, Group O leukocyte reduced apheresis units that have been collected in accordance with Food and Drug Administration (FDA) and Association for the Advancement of Blood and Biotherapies (AABB) requirements. Each production batch consists of apheresis platelet units collected from up to 10 donors.
The pooled units undergo further processing for concentration, addition of dimethyl sulfoxide (DMSO), and freezing at < –65°C. DMSO is the cryoprotectant used in manufacturing and is listed in the FDA Inactive Ingredient Database (IID) for intravenous injection.
They are stored at ≤-65°C for up to 5 years. Thawing and resuspension require approximately 15 minutes.
The U.S. Army Medical Research Acquisition Activity (USAMRAA) part of the DoD, awarded Cellphire with a multi-year contract to develop a U.S. Food and Drug Administration (FDA) licensed CLPH-511 product. As part of this contract, Cellphire is optimizing the manufacture of CLPH-511 and recently closed enrollment for efficacy, due to achieving Non-Inferiority in a Phase 2/3 adaptive clinical trial in cardiopulmonary bypass surgery patients called CRYPTICS conducted in 18 hospitals across the U.S. (NCT04709705).
CLPH-511 Key Designations:
MPP Designation: Cellphire has obtained Medical Priority Product (MPP) designation for CLPH-511 under Public Law No. 115-92 which amended the Federal Food, Drug, and Cosmetic Act (FD&C Act) to increase collaboration and communication between the U.S. Department of Defense (DoD) and the FDA.
Fast Track Designation: In March 2025, U.S. Food and Drug Administration (FDA) granted Fast Track designation for CLPH-511 (Frozen Activated Platelets) Injectable Suspension for the treatment of acute hemorrhage as an alternative to conventional platelets when not available or in short supply.
Cryopreserved Platelet Experience - Single Unit
- More than 3,000 Cryopreserved Platelet (CLPH-511) transfusions have been given in various trials to 1,334 patients between 1972-2014 (Slichter, ‘14) with single donor CLPH-511.
- Significant data from the Dutch and Australian military experience in Afghanistan with 1,143 cryopreserved platelet units transfused into 349 patients suggested they were both safe and effective (Cohn et al 2017; Noorman et al, 2016).
- No significant adverse events associated with the use of CLPH-511 have been reported in any study.
Advantages of CLPH-511 compared to single donor CLPH-511
- Is a pooled, homogeneous, scalable product
- Uses universal, Group O donors (no matching required)
- Is a low volume product with preparation time is less than 15 minutes (compared to 5X volume and ~1 hour preparation time)
- Single donor CLPH-511 is not available in the U.S. as a licensed product
- Cellphire is the only company running a clinical trial in the U.S. seeking an FDA approval for the use of CLPH-511 for the treatment of acute hemorrhage
- CLPH-511 is manufactured using irradiated, and leukocyte-reduced apheresis platelet units collected from up to 10 donors.
CLPH-511 will be licensed as a Biologic (351(a)
This work is supported by the U.S. Army Medical Research and Development Command under Contract No. W81XWH20C0030.
The views, opinions and/or findings contained in this report are those of the author(s) and should not be construed as an official Department of the Army position, policy or decision unless so designated by other documentation.