Inclusion Criteria:
* • 1. Patients aged ≥12 years and ≤65 years at the time of signing the informed consent form (ICF), male or female;
* 2\. Patients with hemophilia A with FVIII activity level \<1% or hemophilia B with FIX activity level ≤2%, confirmed by testing during the screening period or by prior test results;
* \- For patients without inhibitors: FVIII or FIX inhibitor test results during the screening period are negative or below the lower limit of normal (LLN); no bleeding treated with bypassing agents due to inhibitors within at least 6 months prior to screening; no history of immune tolerance induction (ITI) within 3 years prior to screening; and ≥150 exposure days (EDs) of clotting factor replacement therapy;
* \- For patients with inhibitors: FVIII or FIX inhibitor titer during the screening period is high titer (≥5 Bethesda units/mL \[BU/mL\]), or the inhibitor titer is low titer (0.6 BU/mL or the upper limit of normal ≤ inhibitor titer \<5 BU/mL) and treatment with a bypassing agent (rFVIIa or PCC) has already been initiated;
* 3\. ≥6 bleeds requiring treatment with a clotting factor replacement or bypassing agent within the 6-month run-in period (bleeds related to surgery are not counted);
* 4\. No active bleeding symptoms prior to the first administration of SR604 Injection;
* 5\. Able to understand the procedures and methods of this clinical trial, with adequate informed consent; the patient voluntarily participates and signs the informed consent form (ICF).
Exclusion Criteria:
* 1\. Patients with a known history of hypersensitivity to the investigational product or any of its components; 2. Intolerance to subcutaneous (SC) injection, or presence of other local skin abnormalities or skin diseases that affect dosing and safety assessment; 3. Meeting any of the following criteria during the screening period or prior to enrollment:
1. Hemoglobin \<60 g/L;
2. Platelet count \<100×10⁹/L;
3. Abnormal hepatic or renal function: alanine aminotransferase (ALT) or aspartate aminotransferase (AST) ≥2.5× the upper limit of normal (ULN), or total bilirubin ≥1.5× ULN; or serum creatinine (Cr) ≥1.5× ULN;
4. Positive for anti-human immunodeficiency virus (HIV) antibodies; 4. Markedly abnormal coagulation parameters caused by diseases other than hemophilia A or B (e.g., platelet disorders, vitamin K deficiency, etc.); 5. Patients with protein C deficiency or protein S deficiency; 6. History of thrombosis or family history of thrombosis, or history of thrombophilia; 7. Intracranial hemorrhage due to hemophilia A or B within 2 years prior to signing the informed consent form (ICF); 8. Suffering from severe cardiac disease, such as unstable angina, congestive heart failure (New York Heart Association \[NYHA\] class ≥III), severe arrhythmia (QTc interval \>480 ms, corrected by Fridericia's formula), uncontrolled hypertension (systolic blood pressure ≥160 mmHg or diastolic blood pressure ≥100 mmHg), etc.; 9. Received any product containing FVIII within 72 hours prior to the first administration of the investigational product; received any product containing FIX within 96 hours prior to the first administration of the investigational product; received recombinant human coagulation factor VIIa (rFVIIa) within 48 hours prior to the first administration of the investigational product; the washout period for long-acting forms of the above medicinal products is less than 5 half-lives; 10. Used within 1 week prior to screening, or requiring during the trial, any anticoagulants, antifibrinolytics, or chemical drugs, biological products, or traditional Chinese medicines that affect platelet function, including nonsteroidal anti-inflammatory drugs (NSAIDs) such as aspirin; 11. Received non-factor regular replacement therapy within 6 months prior to signing the informed consent form (ICF), such as emicizumab, marstacimab, Fitusiran injection (fitusiran sodium), etc.; 12. Underwent major surgery (e.g., orthopedic surgery, abdominal surgery) within 1 month prior to signing the informed consent form (ICF), or planned to undergo surgery during the study period; 13. Enrolled in another clinical trial and received drug/medical device treatment within 1 month prior to signing the informed consent form (ICF); 14. Patients with mental illness or significant psychiatric disorders, or incapacity or cognitive impairment due to other causes; 15. Planning to have children or donate sperm during the entire trial period and within 6 months after the last dose, or unwilling to use effective physical contraception (e.g., condoms, etc.); 16. Other conditions considered by the investigator to make the patient unsuitable for enrollment, such as alcohol abuse, anticipated poor compliance of the trial participant that makes it impossible to complete dosing and trial follow-up, poorly controlled other chronic diseases, or presence of severe systemic diseases.
