A Study of the Efficacy and Safety of FXS6837 Capsules Compared to Eculizumab for 24 Weeks in Patients With PNH.

Inclusion criteria: 1. Male or female subjects aged ≥ 18 years at screening; 2. Body weight ≥ 40 kg and body mass index (BMI) ≥ 18 kg/m2 at screening; 3. Diagnosis of PNH by the investigator according to the PNH diagnostic criteria, with red blood cell and white blood cell (monocytes or neutrophil) clone levels \> 10% detected by high sensitivity flow cytometry within 6 months before screening or during the screening period; 4. PNH patients with no prior treatment involving any complement inhibitors; 5. At least two measurements during the screening period (2 to 6 weeks apart) showing LDH \> 1.5 × ULN (multiple measurements are allowed during the screening period); 6. Hb meeting one of the following conditions: (1) Hb concentration \< 100 g/L at the first screening visit, and received RBC transfusion therapy due to PNH-related anemia during the screening period; (2) Mean Hb concentration from two measurements during the screening period \< 100 g/L (these two measurements should be 2 to 6 weeks apart; multiple Hb measurements are allowed during the screening period); Exclusion criteria: 1. With laboratory evidence of bone marrow failure during screening (reticulocyte count \< 100 × 109/L, or platelet count \< 30 × 109/L, or neutrophil count \< 0.5 × 109/L); Received acute treatment (such as platelet transfusion, granulocyte colony-stimulating factor) for thrombocytopenia or neutropenia within 30 days before screening; 2. Participants receiving other therapies before screening that have not reached the following stable treatment durations: * Erythropoietin for at least 8 weeks * Immunosuppressants for at least 8 weeks, systemic corticosteroids (≤ 15 mg/day) for at least 4 weeks * Iron, vitamin B12, or folic acid supplementation for at least 4 weeks * Anticoagulants: Vitamin K antagonists (such as warfarin) used for at least 4 weeks with a stable international normalized ratio (INR) (as determined by the investigator), low molecular weight heparin, oral anticoagulants such as aspirin, rivaroxaban, apixaban, etc., for at least 4 weeks; * Hypoxia-inducible factor prolyl hydroxylase inhibitors (HIF-PHI) for at least 8 weeks; * Androgens for at least 4 weeks; 3. History of malignant tumors of any organ or system within 5 years before screening (except local basal cell carcinoma of the skin or carcinoma in situ of the cervix), regardless of whether treatment was received and whether there is evidence of local recurrence or metastasis; 4. History of bone marrow/hematopoietic stem cell or solid organ transplantation (such as heart, lung, kidney, liver); 5. History of splenectomy or planned surgery during the study period; 6. Subjects with significantly abnormal liver function at screening: any parameter of alanine aminotransferase (ALT), γ-glutamyl transpeptidase (GGT), or alkaline phosphatase (ALP) \> 3 × ULN; 7. Human immunodeficiency virus (HIV) infection (HIV antibody positive), active syphilis infection, hepatitis B virus infection (hepatitis B surface antigen positive), active hepatitis C virus infection, or active tuberculosis infection at screening; 8. Subjects with concurrent systemic major diseases, including but not limited to: advanced heart disease (such as New York Heart Association \[NYHA\] class IV), severe lung disease (such as severe pulmonary hypertension \[WHO class IV\]), active hepatitis, severe kidney disease (estimated glomerular filtration rate eGFR \< 30 mL/min/1.73 m2 or chronic kidney disease \[CKD\] stage 4 or dialysis patients), unstable thrombosis, active gastrointestinal bleeding, other hematologic diseases (such as chronic anemia unrelated to PNH), and deemed unsuitable for study participation by the investigator; 9. Known or suspected by investigators to have immunodeficiency diseases or hereditary complement deficiency; 10. History of Neisseria meningitidis infection; History of ≥ 2 episodes of pneumococcal infection; 11. Detected or suspected (as assessed by the investigator) systemic active bacterial, viral (including COVID-19), or fungal infections within 2 weeks before the first dose; Axillary temperature \> 38 °C within 7 days before the first dose; 12. Suspected or known history of allergies to the IPs or any ingredient in the IPs; 13. Received any type of live attenuated vaccine within 4 weeks prior to screening, or plan to receive any live attenuated vaccine during the study; 14. Pregnant or lactating women or those with positive pregnancy test results; 15. Previous history of drug abuse or drug use; 16. Participated in other clinical trials of investigational drugs (or are still within 5 half-lives of the drug, whichever is longer) or medical device clinical trials within 30 days prior to screening, plans to participate in other clinical trials during the study, or having residual effects as assessed by the investigator;