A Proof of Concept Study for 6 Month Treatment in Patients With C3 Glomerulopathy (C3G)

Inclusion Criteria:

- Initial diagnosis of C3GN or DDD 3 months prior to the first dose of study drug and
prior to age 55 years.

- Confirmation of DDD or C3 glomerulonephritis (C3GN) diagnosis by review of a renal
biopsy obtained no more than 30 days (and preferably within 2 weeks) of first dose of
study drug by the study's central pathology laboratory

- Clinical evidence of ongoing disease based on significant proteinuria, defined as ≥1
g/day of protein in a 24-hour urine, attributable to C3G disease in the opinion of the
Principal Investigator (PI), and present prior to study entry and confirmed during
Screening

- Must be willing to comply with study-specific vaccination requirements, including
those for N. meningitidis, H. influenzae, and S. pneumonia

Exclusion Criteria:

- Have a history or presence of any clinically relevant co-morbidities that would make
the participant inappropriate for the study

- Have ever received ACH-0144471

- Have more than 50% fibrosis or more than 50% of glomeruli with cellular crescents on
the pre-treatment renal biopsy

- Have an estimated GFR <30 mL/min for participants19 years of age and older (based on
CKD-EPI creatinine equation [2009]), and <30 mL/min/1.73 m2 for participants <19 years
old (based on "Bedside Schwartz" equation [2009]) at the time of screening or at any
time over the preceding four weeks

- Have C4 levels <80% lower limit of normal (LLN)

- Is a renal transplant recipient or receiving renal replacement therapy

- Have a history of a major organ transplant (e.g., heart, lung, kidney, liver) or
hematopoietic stem cell/marrow transplant

- Have evidence of monoclonal gammopathy of unclear significance (MGUS), infections,
malignancy, autoimmune diseases, or other conditions to which C3G may be secondary

- Have other renal diseases that would interfere with interpretation of the study

- Have comorbid conditions that would interfere with completion of the trial (e.g.,
malignancies, congestive heart failure, recent myocardial infarction)

- Females who are pregnant, nursing, or planning to become pregnant during the study or
within 90 days of study drug administration

- Have a history of febrile illness, a body temperature >38°C, or other evidence of a
clinically significant active infection, within 14 days prior to study drug
administration

- Have evidence of human immunodeficiency virus (HIV) (positive serology for HIV
antibody [HIV Ab]), hepatitis B infection (positive hepatitis B surface antigen
[HbsAg]), or hepatitis C infection (positive anti-HCV antibody [HCV Ab]) at Screening
or historically

- Have any of the following laboratory abnormalities at screening:

- Alanine transaminase (ALT) > upper limit of normal (ULN)

- Aspartate aminotransferase (AST) > ULN

- Absolute neutrophil counts (ANC) <1,000/μL

- Total bilirubin >1.5× ULN

- Indirect bilirubin > ULN

- Any laboratory abnormality that, in the opinion of the PI, would make the
participant inappropriate for the study

NOTE: Additional inclusion/exclusion criteria will apply, per protocol