The goal of this prospective, multicenter, single arm observational study is to evaluate the efficacy and safety of the BFCA regimen in ≥ 40 years old SAA patients undergoing haplo-HSCT.

Inclusion Criteria:

• Severe aplastic anemia;
• Aged 40-60 years old;
• Weight 45Kg-100Kg;
• Eastern Cooperative Oncology Group (ECOG) score ≤3;
• No major organ injury (ECG ejection fraction >45%; bilirubin < 2 times the upper limit of normal value; AST and ALT < 3 times the upper limit of normal value; serum creatinine < 2 times the upper limit of normal value);
• No severe infection;
• Subjects voluntarily participated in this clinical trial and signed the informed consent.

Exclusion Criteria:

• With other hematologic diseases;

• Expected survival of less than 1 month;

• Previous autologous or allogeneic hematopoietic stem cell transplantation;

• Pregnant patients;

• Patients with severe mental or neurological disorders that would affect the ability to provide informed consent and/or to report or observe adverse events;

• Other conditions that the investigator determines to be inappropriate for enrollment.

• Current or recent (<4 weeks prior to screening) clinically serious viral, bacterial, fungal, or parasitic infection

• A history of symptomatic herpes zoster infection within 12 weeks prior to screening

• Active or chronic viral infection from hepatitis B virus (HBV), hepatitis C virus (HCV), or human immunodeficiency virus (HIV)

• Have evidence of active tuberculosis (TB), or have previously had evidence of active TB and did not receive appropriate and documented treatment, or have had household contact with a person with active TB and did not receive appropriate and documented prophylaxis for TB

• Exposure to a live vaccine within 12 weeks prior to enrollment or expected to receive a live vaccine during the study

• Clinically significant thrombotic event within 24 weeks of screening or are on anticoagulants and in the opinion of the investigator are not well controlled

• Myocardial infarction (MI), unstable ischemic heart disease, stroke, or New York Heart Association Stage IV heart failure

• A history or presence of cardiovascular, respiratory, hepatic, gastrointestinal, endocrine, neurological, or neuropsychiatric disorders or any other serious and/or unstable illness that, in the opinion of the investigator, could constitute an unacceptable risk when taking investigational product or interfere with the interpretation of data

• Any of the following specific abnormalities on screening laboratory tests:

  1. ALT or AST >2 x ULN, or total bilirubin ≥1.5 x ULN
  2. hemoglobin <9 g/dL, or total white blood cell (WBC) count <2,500/µL, or neutropenia (absolute neutrophil count <1,200/µL), or lymphopenia (lymphocyte count <750/µL)
  3. eGFR <50 mL/min/1.73 m2

Patients aged 40-60 years old who are diagnosed with severe aplastic anemia according to NCCN guidelines and who will receive haploidentical hematopoietic stem cell transplantation at the centers will be recruited.