Study to Evaluate the Safety, Tolerability of BCX9930 in Participants With Either Complement 3 Glomerulopathy (C3G), Immunoglobulin A Nephropathy (IgAN), or Primary Membranous Nephropathy (PMN)

Approximately 14 eligible participants with C3G will be enrolled.

Drug: BCX9930

Approximately 14 eligible participants with IgAN will be enrolled.

Drug: BCX9930

Approximately 14 eligible participants with PMN will be enrolled.

Drug: BCX9930

Administered orally at a dose of 200 mg twice daily for the first 2 weeks, then 400 mg twice daily

Plazo: Baseline, Week 12

Urinary protein/creatinine ratio (mg/mmol) =urine protein concentration (mg/dL)/ urine creatinine concentration (mmol/dL). Decrease of urinary protein/creatinine ratio means improvement of renal disease.

Plazo: Baseline, Week 24

Urinary protein/creatinine ratio (mg/mmol) =urine protein concentration (mg/dL)/ urine creatinine concentration (mmol/dL). Decrease of urinary protein/creatinine ratio means improvement of renal disease.

Plazo: Baseline, Weeks 12, 24,

No informado en este registro.

Plazo: Baseline, Weeks 12, 24

eGFR was calculated by the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) formula for participants ≥ 18 years old and by the bedside Schwartz formula for participants ≤ 18 years old. eGFR was reported in milliliter per minute per 1.73 per square meter (mL/min/1.73m\^2).

Plazo: From first dose up to safety follow-up period (Week 28)

An Adverse event (AE) was any untoward medical occurrence in a clinical study participant. TEAEs were defined, within a dosing group, as AEs that started on or after the first dose of study treatment through 30 days after the last dose of study drug.

Plazo: From first dose up to safety follow-up period (Week 28)

An AE was any untoward medical occurrence in a clinical study participant. TEAEs were defined, within a dosing group, as AEs that started on or after the first dose of study treatment through 30 days after the last dose of study drug.

Plazo: From first dose up to safety follow-up period (Week 28)

An AE was any untoward medical occurrence in a clinical study participant. TEAEs were defined, within a dosing group, as AEs that started on or after the first dose of study treatment through 30 days after the last dose of study drug.

A serious adverse event (SAE) was an adverse event/reaction that results in any of the following outcomes:

• Death
• Is life-threatening (participant was at immediate risk of death at the time of the event; it does not refer to an event that hypothetically might have caused death if it were more severe)
• Requires participant hospitalization (formal admission to a hospital for medical reasons) or prolongation of existing hospitalization
• Results in persistent or significant disability/incapacity (ie, there was a substantial disruption of a person's ability to carry out normal life functions)
• Is a congenital anomaly/birth defect

Plazo: From first dose up to safety follow-up period (Week 28)

An AE was any untoward medical occurrence has no causal relationship with the study drug or with the clinical study itself. It was an unfavorable \& unintended sign, symptom, syndrome, or illness that developed or worsened during clinical study.

TEAEs: AEs that started on or after first dose of treatment through 30 days after the last dose of study drug. All AEs were graded using the CTCAE Grades 1 through 5.

Grade 1: Mild; asymptomatic or mild symptoms; clinical or diagnostic observations only; intervention not indicated

Grade 2: Moderate; minimal, local or noninvasive intervention indicated; limiting age-appropriate instrumental activities of daily living (ADL)

Grade 3: Severe or medically significant but not immediately life-threatening; hospitalization or prolongation of hospitalization indicated; disabling; limiting self-care ADL

Grade 4: Life-threatening consequences; urgent intervention indicated

Grade 5: Death

Participants with Grades 3 or 4 AEs were reported

Plazo: From first dose up to safety follow-up period (Week 28)

Treatment-emergent Laboratory Abnormality were defined as an event that started on or after the first dose of study treatment through 30 days after the last dose of study drug.

CTCAE Grades for laboratory abnormalities include:

Grade 1: Mild; asymptomatic or mild symptoms; clinical or diagnostic observations only; intervention not indicated.

Grade 2: Moderate; minimal, local or noninvasive intervention indicated; limiting age-appropriate instrumental ADL.

Grade 3: Severe or medically significant but not immediately life-threatening; hospitalization or prolongation of hospitalization indicated; disabling; limiting self-care ADL.

Grade 4: Life-threatening consequences; urgent intervention indicated.

Grade 5: Death

Participants with Grades 3 or 4 laboratory abnormality were reported.

An Open-Label, Safety, Tolerability, and Proof-of-Concept Study of Oral BCX9930 Therapy in Subjects With Complement 3 Glomerulopathy, Immunoglobulin A Nephropathy, or Primary Membranous Nephropathy