To Evaluate the Safety, Tolerability, Pharmacokinetics, Pharmacodynamics, and Efficacy of KP104

Inclusion Criteria:

Initial Treatment Period:

• Documented diagnosis of PNH confirmed by flow cytometry evaluation of white bloodcells and red blood cells, with granulocyte or monocyte clone size of >= 10 percent (%) within 6 months of the Screening visit.

• Presence of 1 or more PNH-related signs or symptoms within 3 months of initiation ofScreening.

• LDH >= 2.0 × upper limit of normal (ULN) at screening.

• Hemoglobin <= 10.0 g/dL at screening.

• Females of childbearing potential and males must practice effective contraceptionfrom Screening until 28 days after the end of study (EOS) visit.

• Females of childbearing potential must have a negative pregnancy test at Screeningand within 24 hours prior to dosing of study drug.

Extension Treatment Period (OLE):

• Complete the 12-week (weekly dosing) or 13-week (biweekly dosing) Initial TreatmentPeriod per the protocol.

• Benefited from KP104 treatment and will continue benefiting from KP104 treatment perthe investigator's judgement.

• Willing to participate in Extension Treatment Period, able to comply with thisprotocol and be available for the entire duration of the study.

Exclusion Criteria:

Initial Treatment Period:

• Any clinically significant poorly controlled underlying illness other than PNH perdiscretion of investigators.

• Treatment of any infection with IV (within 30 days of Screening) or oral (within 14days of Screening) antibiotics, antivirals, or antifungals.

• History of meningococcal infection.

• History of untreated tuberculosis.

• History of splenectomy

• Positive serology for Hepatitis C Virus (HCV) ribonucleic acid (RNA) or humanimmunodeficiency virus (HIV) at Screening

• History of bone marrow or stem cell transplantation

• Absolute neutrophil count (ANC) <500 cells per microliter (cells/μL)

• Reticulocyte count< 100 x 10^3 cells/μL

• Platelet count< 30,000 cells/μL

• History of systemic autoimmune disease

• Estimated glomerular filtration rate (eGFR) <30 milliliters/minute/1.73 meter square (mL/min/1.73 m^2) calculated by Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation.

Extension Treatment Period (OLE):

• Women who are pregnant.

• Women of childbearing potential and men with sexual partners of childbearingpotential who are not using adequate contraception and who are not willing to useadequate contraception.

• Any medical condition that, in the opinion of the investigator, may pose a safetyrisk to a participant in this study, or may interfere with study participation.

Other protocol defined Inclusion/Exclusion criteria may apply.