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 blood cells 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 of Screening. * 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 contraception from Screening until 28 days after the end of study (EOS) visit. * Females of childbearing potential must have a negative pregnancy test at Screening and 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 Treatment Period per the protocol. * Benefited from KP104 treatment and will continue benefiting from KP104 treatment per the investigator's judgement. * Willing to participate in Extension Treatment Period, able to comply with this protocol 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 per discretion of investigators. * Treatment of any infection with IV (within 30 days of Screening) or oral (within 14 days 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 human immunodeficiency 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 childbearing potential who are not using adequate contraception and who are not willing to use adequate contraception. * Any medical condition that, in the opinion of the investigator, may pose a safety risk to a participant in this study, or may interfere with study participation. Other protocol defined Inclusion/Exclusion criteria may apply.