Transfusion-dependent thalassemia (TDT) requires lifelong, regular red blood cell (RBC) transfusions. Conventionally stored RBCs develop biochemical and structural "storage lesions," driven largely by oxidative stress, which may reduce post-transfusion survival and contribute to anemia, hemolysis, metabolic abnormalities, and iron overload. Hypoxic storage has emerged as a strategy to mitigate oxidative deterioration and preserve RBC quality.

The Hemanext One® system allows processing and storage of RBCs under hypoxic conditions (low oxygen and carbon dioxide). Early studies have shown improved metabolic preservation compared with standard storage. In Greece, and specifically at the National Center for Blood Transfusion (EKEA), hypoxically stored RBCs have already been introduced into routine transfusion practice for selected TDT patients, independently of this study.

This study is observational and does not assign or provide Hemanext-processed RBCs. Instead, it aims to systematically evaluate the hematologic, metabolic, and clinical impact of receiving hypoxically stored RBCs in adult TDT patients who are already being transfused with Hemanext units as part of their clinical care.

The study includes a 12-week baseline period based on conventional transfusions, followed by a treatment phase of at least 3 months during which patients continue receiving Hemanext-processed RBCs as provided by EKEA; the treatment phase may be extended for each participant up to the study-wide data cut-off date. Informed consent is obtained before any study-related data collection.

The primary objective is to compare transfusion burden (cc/kg) between baseline conventional RBCs and hypoxically stored RBCs administered in routine care. Secondary objectives include changes in pre-transfusion hemoglobin, total hemoglobin mass, hemolysis and erythropoiesis markers, metabolic indicators, iron overload parameters, quality of life, and safety outcomes. Findings will provide real-world evidence on the feasibility and clinical impact of hypoxically stored RBCs in chronically transfused patients.

Transfusion-dependent β-thalassemia (TDT) is a severe inherited hemoglobinopathy requiring lifelong red blood cell (RBC) transfusions every 2 to 4 weeks. Patients typically receive 2-4 units per month, and their long-term survival and quality of life depend on the safety and functional integrity of the transfused RBCs. During standard storage, RBCs undergo progressive biochemical and morphological deterioration known as "storage lesions," which include oxidative damage, protein oxidation, enzymatic dysfunction, membrane remodeling, depletion of 2,3-diphosphoglycerate (2,3-DPG), and metabolic instability. These alterations reduce post-transfusion RBC survival and oxygen-delivery capacity and may contribute to hemolysis, increased transfusion requirements, iron accumulation, and other clinical complications. Oxygen exposure during storage is a major driver of oxidative injury, and reducing oxygen levels has been shown to mitigate the severity of storage lesions.

The Hemanext One® RBC Processing and Storage System is designed to reduce and maintain low oxygen and carbon dioxide levels during storage, thereby limiting oxidative deterioration of stored RBCs. Preclinical and early clinical evaluations have demonstrated improved preservation of RBC membrane integrity, metabolic profiles, and functional stability compared with conventional storage. The system has received FDA De Novo marketing authorization and CE marking. In Greece, RBC units processed with Hemanext One® are already used at the National Center for Blood Transfusion (EKEA) and are provided to selected thalassemia patients as part of standard clinical practice, independently of this study.

This study is prospective, observational, and entirely non-interventional. The investigators do not influence or assign transfusion type. All patients receive blood units according to routine clinical practice at EKEA, and participation in the study begins only after the patient signs informed consent. No study procedures or assessments occur before consent is obtained.

The study includes a 12-week baseline period, based on retrospective or prospectively collected routine clinical data during which the patient received conventionally stored RBCs. This is followed by an observational treatment period during which patients continue to receive hypoxically stored RBCs processed with the Hemanext One® system, exactly as provided by EKEA. The duration of this treatment observation phase is at least three months and may be extended until the study-wide data cut-off date, depending on RBC availability and patient preference. The study does not modify transfusion thresholds, clinical decision-making, or transfusion scheduling.

The primary objective of the study is to assess changes in transfusion burden, measured in cc/kg, after the transition from conventionally stored to hypoxically stored RBCs. Secondary objectives include the evaluation of changes in pre-transfusion hemoglobin, hemolysis and erythropoiesis markers, metabolic indicators, iron overload indices such as serum ferritin, patient-reported quality of life using validated instruments including the FACIT-F version 4 questionnaire, and the frequency and nature of transfusion-related adverse events. All information is obtained exclusively from routine clinical assessments and standard laboratory evaluations. No additional blood draws or study-specific procedures are required. A subset of patients may voluntarily contribute residual blood samples for more detailed laboratory evaluation, provided that these analyses are within the scope of routine laboratory capabilities.

All collected data will be coded and managed according to applicable data protection regulations. The investigators will not influence the assignment of blood unit type, which remains the responsibility of the transfusion service. This real-world evidence study aims to generate clinically meaningful insights into the safety, feasibility, and effectiveness of hypoxically stored RBCs in patients with TDT, supporting future evidence-based evaluation of their use in chronically transfused populations.

Inclusion Criteria

Subjects must satisfy the following criteria to be enrolled in the study:

1. Subject is ≥ 18 years of age at the time of signing the informed consent form (ICF).
2. Subject must understand and voluntarily sign an ICF prior to any study-related assessments/procedures being conducted.
3. Subject has documented diagnosis of β- transfusion dependent thalassemia, defined as ect: ≥ 6 RBC units/24 weeks and no transfusion-free period for ≥ 42 days during the 24 weeks prior enrollment.
4. Transfusion history (including units or cc) for at least 6 months prior to enrollment needs to be available.
5. Subject is on chelation therapy and a fairly stable dose for at least 6 months prior to enrollment.
6. Chronic therapies (including hydroxyurea) are allowed as long as the medication dose has been stable for at least 6 months prior to enrollment.
7. Having been exposed to PRBC transfusions prepared with the Hemanext One processing system

Exclusion Criteria

The presence of any of the following will exclude a subject from enrollment:

1. Subject has currently or has a history of any significant medical condition, laboratory abnormality, or psychiatric illness.
2. Subject has had positive Coombs (antiglobulin) test anytime during the 6 months prior to enrollment.
3. Subject is scheduled to undergo or has recently (in the last 6 months) undergone splenectomy.
4. Use of luspatercept during the period of 6 months prior to enrollment and during the trial is not allowed.
5. Participation in an interventional clinical trial or use of experimental medications during the period of 6 months prior to enrollment and during the trial is not allowed.

The study population consists of adults aged 18 years or older diagnosed with β-transfusion dependent thalassemia (TDT) who require regular red blood cell (RBC) transfusions, defined as receiving at least 6 units of RBCs over 24 weeks without a transfusion-free interval longer than 42 days. Participants must have a documented transfusion history and be on a stable chelation therapy regimen for at least six months prior to enrollment. Patients receiving stable doses of chronic therapies, including hydroxyurea, are eligible. Individuals with significant medical, laboratory, or psychiatric conditions that may interfere with study participation, or with a positive Coombs test within six months prior to enrollment, are excluded.