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VOYXACT (Sibeprenlimab)
Sibeprenlimab (brand name VOYXACT)
This is a new prescription medication used to treat IgA nephropathy (IgAN), a kidney disease caused by the buildup of abnormal IgA antibodies (called Gd-IgA1) in the bloodstream. These antibodies are produced in the gut, enter your bloodstream, and eventually reach the kidneys. Once in the kidneys, they trigger significant inflammation that can damage the kidneys. This damage can lead to blood and protein in the urine and, over time, loss of kidney function.
Medically reviewed by Dr. Vasquez Rios, MD
What Is VOYXACT?
VOYXACT (Sibeprenlimab) is a type of medicine known as a monoclonal antibody. These are highly specific proteins made in a laboratory. They help the immune system block the processes that drive certain diseases.
In IgAN, immune cells in the gut make too much of the abnormal IgA (Gd-IgA1). Too much abnormal IgA contributes tokidney inflammation and long-term kidney scarring.
VOYXACT (Sibeprenlimab) was developed to:
- Reduce the production of harmful Gd-IgA1 (abnormal IgA) in the gut
- Lower inflammation in both the gut and the kidney
- Prevent ongoing kidney damage and help stabilize kidney function over time
How does VOYXACT work?
VOYXACT (Sibeprenlimab) works by blocking APRIL, a protein that normally helps the body produce IgA antibodies. Because IgAN is driven by the overproduction of the abnormal form of IgA, lowering APRIL can:
- Reduce the amount of abnormal IgA entering the bloodstream
- Decrease inflammation inside the kidneys
- Slow or prevent further kidney injury
- Reduce protein loss in the urine (proteinuria)
Importantly, VOYXACT does not suppress the entire immune system. It targets a very specific part of the immune system linked to IgAN. Targeting only part of the immune system helps to limit unwanted side effects.
How is VOYXACT administered?
VOYXACT is given as a subcutaneous injection—meaning it is injected just under the skin.
- Route of administration: Subcutaneous
- Dose: 400 mg once every four weeks
- How it is supplied: Prefilled syringe
- Who gives the injection: You or a caregiver, after proper training
- Injection sites: Front of the thigh, abdomen, or the back of the upper arm (if given by a caregiver)
Most patients find this method convenient because it does not require visits to an infusion center.
Is VOYXACT right for me?
VOYXACT may be an option if you have:
- Biopsy-proven IgA nephropathy, and
- Persistent proteinuria even with supportive therapies (such as ACE inhibitors or ARBs), or
- A high risk of kidney function decline, now defined as proteinuria above 0.3 grams
Your doctor may recommend sibeprenlimab if:
- Your proteinuria remains elevated
- Your kidney function is gradually worsening
- You prefer a therapy that targets the underlying cause of IgAN
VOYXACT may not be appropriate during active infections, acute illness, pregnancy, or breastfeeding. Please talk with your doctor before starting or continuing the medication if any of these apply to you.
*Note: The decision to prescribe a medication is the responsibility of your physician/primary care provider based on his/her evaluation of your condition. The above is meant for informational purposes only. Discuss this information and all information about drugs/medications with your physician before starting or stopping any medication.
Frequently Asked Questions
Clinical studies have shown that Sibeprenlimab:
- Significantly reduces proteinuria, an important marker of kidney inflammation
- Slows the decline in kidney function (eGFR) compared with placebo (or receiving no treatment)
- Produces early improvements that continue over months of treatment
- May be especially effective in patients with more active IgA Nephropathy, these patients usually have higher levels of Gd-IgA1 (abnormal IgA antibodies); manifesting as too much blood/protein in the urine or decreasing kidney function.
These findings suggest that Sibeprenlimab can reduce long-term kidney damage by directly targeting a key driver of IgAN.
In clinical trials, sibeprenlimab was generally well tolerated.
Possible side effects include:
- Mild injection-related reactions (such as fever, chills, or headache)
- Upper-respiratory symptoms (sore throat, nasal congestion)
- Fatigue or mild nausea
- Lower levels of normal IgA used to fight some infections (your care team will monitor this)
Most side effects were mild and occurred in a small number of patients. Because the medication lowers IgA levels, which is a part of your immune system, your doctor will monitor you for any signs of infection and perform regular blood tests.
VOYXACT is unique because it:
- Targets the root cause of IgAN — overproduction of abnormal IgA in the gut
- Reduces kidney inflammation at its source
- Reduces protein in the urine and helps protect long-term kidney function
- Does not broadly suppress the immune system or lower blood pressure
Other treatments (like ACE inhibitors, ARBs, SGLT2 inhibitors, sparsentan, or budesonide) either reduce kidney stress or inflammation but do not specifically target the part of the immune system responsible for IgA production.
VOYXACT is a specialty medication, so it is not available at regular retail pharmacies.
Here is the typical process:
- Your nephrologist determines whether you are a good candidate
- Your doctor’s office submits a prior authorization to your insurance
- Once approved, the medication is sent to a specialty pharmacy
- You (or your caregiver) administer the monthly injection at home after training
Your kidney care team will walk you through each step and help coordinate delivery, insurance approvals, and training.
