About VALIANT

The study is evaluating the safety and effectiveness of an investigational medication in young people and adults who have C3G or IC-MPGN. The investigational medication is called pegcetacoplan, and is a "targeted C3 inhibitor”.

The VALIANT study will primarily assess whether pegcetacoplan has an effect on the leakage of protein into urine, called proteinuria. Proteinuria is a signal of damage to the kidneys.

In people with C3G or IC-MPGN, a protein called complement C3 is over-activated, and can cause kidney damage when its breakdown products form harmful deposits in the kidney. Pegcetacoplan inhibits the C3 protein, so the VALIANT study will help us to find out if this action can help to slow or reduce kidney damage.

Participants must:

• Be at least 12 years old
• Have a diagnosis of primary C3G or IC-MPGN
• Have significant proteinuria (protein in the urine) confirmed during the study screening process
• Have normal to moderately impaired kidney function as indicated by estimated glomerular filtration rate (eGFR) of at least 30 mL/min/1.73 m²
• Weigh 30 kg–100 kg (66–220 pounds)
• Be willing to use contraception until at least 3 months after the last dose of the investigational medication

Both people who have not had a kidney transplant and those who have had a kidney transplant can be considered for this study.

Additional criteria will be assessed at the research site to confirm eligibility.

The VALIANT study is not for people with C3G or IC-MPGN who:

• Are under 12 years of age
• Are being treated with rituximab, belimumab, or eculizumab, and need to continue taking these medications
• Have or have had hepatitis B, hepatitis C, or HIV
• Are pregnant or breastfeeding

Additional criteria will be assessed at the research site to confirm eligibility.

The investigational medication in this study is called pegcetacoplan (peg-set-a-koé-plan). It is administered via a needle under the skin (subcutaneously) twice a week. Participants and/or their caregivers will be trained and supported to administer the study medication at home.

Investigational means that pegcetacoplan is not approved by any health authority for the treatment of C3G or MPGN.

After completing the screening period to confirm that the patient is able to participate in the study, individuals will be randomly assigned (randomized) to one of two treatment groups.

• Group 1: Will receive pegcetacoplan for the 12-month treatment period.
• Group 2: Will receive placebo for the first 6 months of the treatment period, and then receive pegcetacoplan for the remaining 6 months of the treatment period.

The placebo medication looks like the investigational medication but has no medically active ingredients. There is an equal chance (50%) of being assigned to Group 1 or Group 2 at the start of the study treatment period.

Study participants will not know their study treatment group assignment and they will not have the option of choosing their group.

Study participants who complete the 1-year study treatment period may enter a long-term extension study where they will continue receiving the investigational medication. Participants will enter an 8-week follow-up period after their last dose of the study medication.

After completing the screening period, participation in the study will last for approximately 14 months (60 weeks)

• 1-year study treatment period
• 8-week follow-up period after the last dose of investigational medication

Study participants who are determined to be benefiting medically from the investigational medication may be able to participate in a long-term extension study after completing the 1-year study treatment period, where they will continue receiving pegcetacoplan.

Study participants will have approximately 14 in-clinic visits during the 1-year study treatment period and 2 visits during the 8-week follow-up period.

Reimbursement or pre-paid travel support may be available to study participants.

Main study assessments and procedures include, but are not limited to:

• Urine samples, including both samples collected at study visits and samples collected at home
• Adults only: kidney biopsies (where possible, these will be combined with standard care biopsies)
• Blood samples
• Questionnaires
• Measurements of heart function (ECG)
• Physical examinations
• Completion of an electronic diary to record dosing with study medication and home urine collections

The study doctor will discuss this with you in more detail.

All study-related tests and evaluations, and study medications will be provided at no cost to study participants. The study team can provide more detailed information. In addition, reimbursement or pre-paid travel support may be available to study participants.

No, connecting with a site does not obligate you or your child to participate, nor does it guarantee your/their eligibility to participate in the study. Participating in this or any clinical trial is completely voluntary. Individuals who decide to participate in a research study are always free to withdraw at any time for any reason without any penalty or effect on their future medical care.

Should COVID-19, or restrictions related to the pandemic, affect the ability of participants to go to the clinic for study visits, the study doctor will discuss the available options with participants to ensure essential study related treatment and monitoring is continued.