The purpose of this study is to evaluate the efficacy of HSK39297 tablets in paroxysmal nocturnal hemoglobinuria (PNH) patients with anemia after stable treatment of anti-C5 antibody.

Inclusion Criteria:

• Age ≥ 18 and ≤ 75 years, Male and female patients.
• Diagnosis of PNH based on flow cytometry showing >10% granulocyte clone size during the screening period.
• Stable use of Anti-C5 antibody at least 6 months prior to enrollment.
• Hemoglobin level < 10 g/dL at screening.

Exclusion Criteria:

• Hereditary or acquired complement deficiency.
• Active primary or secondary immunodeficiency.
• History of splenectomy, bone marrow/hematopoietic stem cell or solid organ transplants.
• History of recurrent invasive infections caused by encapsulated organisms( e.g. meningococcus or pneumococcus) or Mycobacterium tuberculosis.
• Patients with laboratory evidence of bone marrow failure (reticulocytes < 100x109/L, or platelets < 30x109/L or neutrophils < 0.5x109/L).
• Active systemic infection within 2 weeks prior to study drug administration.
• History of serious comorbidities that have been determined to be unsuitable for participation in the study.
• Pregnant or Lactating women.