Disease information
C3G (C3 glomerulopathy) is a rare, serious and progressive kidney disease. It is caused by the overactivation of part of the immune system, called the complement system.
Primary IC-MPGN (immune-complex membranoproliferative glomerulonephritis) is a rare, serious and progressive kidney disease. It is caused by the overactivation of part of the immune system, called the complement system.
Both C3G and primary IC-MPGN are rare kidney diseases that affect the glomeruli (the tiny filters in your kidneys) and are caused by the overactivation of the complement system. A kidney biopsy helps tell them apart based on what is deposited in the kidney.
In C3G:
A biopsy typically shows mostly C3C3C3 is a naturally occurring protein that is part of your body's immune system. In people with C3G or primary IC-MPGN, C3 can build up in the kidneys and cause damage over time. (complement 3 protein) fragments in the kidneys, with little to no immunoglobulins (antibodies) present.
In primary IC-MPGN:
A biopsy shows mostly immunoglobulin (antibodies) deposits or both immunoglobulin and C3 deposits in the kidneys. Additional tests are often needed to rule out other causes.
Common symptoms include foamy or frothy urine (a sign of too much protein in the urine), blood in the urine, swelling in the legs, ankles, or feet, fatigue, and high blood pressure. These symptoms are not specific to C3G or primary IC-MPGN, which is why regular monitoring and additional lab tests or biopsies can play important roles in earlier diagnosis.
Yes. C3G can come back after a kidney transplant because the complement system continues to be overactivated.
Diagnosis
Diagnosis typically starts with a combination of blood and urine tests. These measure protein in the urine (proteinuriaProteinuriaProteinuria is the presence of too much protein in your urine. It means your kidneys’ filters aren’t working properly and are letting protein leak out. Proteinuria isn’t a disease itself, but it can be a sign of kidney damage or other health issues.) and something called estimated glomerular filtration rate (eGFReGFReGFR is a blood test that shows how well your kidneys are filtering waste. A higher number means better kidney function.). Both of these tests help give your doctor a picture of how well your kidneys are working.
That being said, a kidney biopsy is the only way to confirm a C3G or primary IC-MPGN diagnosis.
Yes. A kidney biopsy is the only definitive way to confirm a diagnosis of C3G or primary IC-MPGN.
During this procedure, a small sample of kidney tissue is examined under a microscope. A special dye is used to detect C3 fragment buildup and identify whether deposits are mainly C3 fragment or if they include immunoglobulins (antibodies). This helps confirm your diagnosis and distinguish C3G and primary IC-MPGN.
A low C3 level in the blood can be a sign that the complement system is overactivated. In C3G and primary IC-MPGN, low C3 can help your doctor assess how active the disease is. Your doctor will interpret this result alongside your biopsy findings and other tests.
Treatment
There is currently no cure for C3G or primary IC-MPGN. However, treatment can help protect your kidneys from ongoing damage by slowing disease progression.
With targeted treatment and consistent monitoring, many patients are able to reduce the protein in their urine and maintain kidney function.
A primary goal is to reduce proteinuria and slow the progression of kidney damage. A retrospective study* has shown that achieving at least a 50% reduction in proteinuria at 12 months is associated with a lower risk of progressing to kidney failure.
*A retrospective study looks at existing patient records; this was not a new treatment trial. The results showed a link between lower protein in the urine and better kidney outcomes.
This does not prove that lowering protein will always prevent kidney failure.
EMPAVELI is a prescription medicine approved for adults and children 12 years of age and older with C3G or primary IC-MPGN, to reduce levels of protein in the urine (proteinuria). It is the only FDA-approved treatment specifically for these conditions that targets C3, a key protein that contributes to complement overactivation.
In C3G and primary IC-MPGN, complement system overactivation leads to excessive C3 fragment buildup in the kidneys, which can cause inflammation and lead to damage in your kidneys.
EMPAVELI works by directly targeting C3, helping to reduce buildup.
See how EMPAVELI targets 1 key driver of disease progression
Because complement inhibitors, like EMPAVELI, affect your immune system, they can lower your ability to fight certain bacterial infections.
To help reduce this risk, certain vaccines are recommended before starting treatment. Your care team will guide you on what vaccines you may need and when to receive them.
The EMPAVELI REMS program ensures your safety is a top priority.
REMS is a safety program run by the FDA. Before you can take EMPAVELI, your healthcare provider must enroll in the program and will provide you with the following:
- Counseling on the risk of serious infections caused by certain bacteria
- Information about the symptoms of serious infections
- Appropriate vaccinations against serious infections caused by encapsulated bacteria
- You will receive antibiotics if you need to start EMPAVELI right away and are not up to date on your vaccines
Starting a conversation about a new treatment can feel overwhelming, but being prepared can make all the difference. Before your visit, think about how C3G or primary IC-MPGN is affecting your daily life, note any symptoms you've been experiencing, and gather your most recent lab results.
During your appointment, consider asking: How could EMPAVELI help me reach my treatment goals? How does it work? And how would it fit into my routine?
To help you make the most of that conversation, we've created a Doctor Discussion Guide you can fill out before, during, and after your visit. This way so you can leave with clarity, confidence, and a plan.