Chronic inflammatory demyelinating polyneuropathy (CIDP) is a rare condition that affects the nerves outside your brain and spinal cord. In CIDP, your immune system mistakenly attacks the protective covering around these nerves, called myelin. This can lead to numbness, tingling, muscle weakness, and fatigue, often starting in the legs and arms.
CIDP symptoms may gradually worsen or improve for a time before returning. When symptoms return or get worse after a period of improvement, it is called a relapse. Without treatment, some people with CIDP eventually end up needing a wheelchair.
One option for managing CIDP long-term is Hizentra. Hizentra is given as an infusion under your skin, which is different from how several other immune globulin treatments are given. The FDA approved Hizentra in March 2018 as a maintenance therapy to help prevent CIDP relapse in adults. It was the first subcutaneous immune globulin treatment approved for CIDP.
This article covers how Hizentra works, who it's approved for, how it was studied, and what the studies found. You may also be interested in reading about Hizentra's side effects and interactions.
How Does Hizentra Work for CIDP?
Researchers believe CIDP happens because the immune system makes antibodies and immune cells that attack myelin, the fatty covering that protects nerve fibers and helps them send signals quickly. When myelin is damaged, nerve signals slow down or get interrupted. This is what causes the weakness and numbness seen in CIDP.
Hizentra contains immunoglobulin G (IgG), which is a mix of antibodies collected from human plasma (the liquid part of blood) donated by many people. Researchers haven't fully worked out exactly how giving extra IgG helps people with CIDP. It's thought to work by changing how the immune system behaves, which may help calm the attack on myelin. This effect is sometimes called immune modulation.
Hizentra had already been used for years to treat people with weakened immune systems who don't make enough of their own antibodies (a condition called primary immunodeficiency). For CIDP, the goal of Hizentra treatment is not to replace missing antibodies. Instead, it's to use IgG's immune-calming effect to help prevent relapse.
Is Hizentra Right for Me?
Hizentra is approved for maintenance therapy in adults with CIDP. It helps prevent relapse of neuromuscular disability and impairment. It's meant for people who are already being treated for CIDP, not as a first treatment when CIDP is newly diagnosed.
Before starting Hizentra, you'll typically need to show that you respond to immune globulin treatment given into a vein, called intravenous immunoglobulin (IVIG). Your health care provider may have you continue on IVIG for a while and confirm that your CIDP symptoms are stable before switching you to Hizentra. This step helps make sure that any future improvement or decline can be linked to the switch itself, rather than to unrelated changes in your condition.
Hizentra isn't approved for use in children with CIDP. It is also not approved to treat CIDP relapses once they happen. If you have a relapse while on Hizentra, your health care provider will likely treat the relapse with IVIG and then decide whether to continue Hizentra afterward.
Your health care provider will also check for reasons Hizentra may not be a good fit for you, such as a history of severe allergic reactions to immunoglobulin products, a rare condition called hyperprolinemia, or IgA deficiency with antibodies against IgA. Hizentra also carries a boxed warning about the risk of blood clots (thrombosis). So, your health care provider will ask about your personal risk factors, such as a history of blood clots, immobility, or certain heart and blood vessel conditions.
How Do I Use Hizentra for CIDP?
Hizentra is given as a subcutaneous infusion, meaning it's injected under the skin rather than into a vein. You'll use an infusion pump to deliver the medicine slowly, usually into your abdomen, thigh, upper arm, or hip, through needles placed in up to eight spots at once. Many people learn to give themselves Hizentra at home after training with a health care provider.
For CIDP, the typical starting dose is 0.2 grams per kilogram (g/kg) of body weight each week, usually split into one or two infusion sessions on one or two days in a row. You'll likely start Hizentra about a week after your last IVIG infusion. If your symptoms get worse on this dose, your health care provider may increase it to 0.4 g/kg per week. In the clinical study, this higher dose was also shown to be safe and effective.
Don't change your dose or stop using Hizentra on your own, even if you feel like it's working well or not working at all. Let your health care provider know about any changes in your symptoms so they can adjust your treatment plan if needed.
How Was Hizentra Studied for CIDP?
The FDA's approval of Hizentra for CIDP was based on a study called PATH (the Polyneuropathy And Treatment with Hizentra study). This was a randomized, double-blind, placebo-controlled trial, which means participants were randomly assigned to a treatment group, and neither the participants nor the study staff knew who was getting Hizentra and who was getting a placebo (a look-alike solution with no active medicine) until the study ended.
The PATH study included 172 adults with CIDP from North America, Europe, Israel, Australia, and Japan who had already responded to IVIG treatment. Before the comparison phase of the study began, all participants went through a standard IVIG treatment period to confirm their CIDP symptoms were stable. At the start of the study, participants were, on average, in their mid-50s to late-50s depending on the group. More participants were men than women.
Participants were then randomly split into three groups for 24 weeks: a low-dose Hizentra group (0.2 g/kg weekly), a high-dose Hizentra group (0.4 g/kg weekly), or a placebo group. The main thing researchers measured was the percentage of people who had a CIDP relapse, defined as a worsening on a standard disability scale, or who left the study for any other reason during those 24 weeks.
What Are the Main Benefits of Hizentra Based on Studies?
During the 24-week comparison period, fewer people on Hizentra had a relapse or left the study compared to people on the placebo.
- In the placebo group, 63% of people had a relapse or left the study.
- In the low-dose Hizentra group, 39% of people had a relapse or left the study.
- In the high-dose Hizentra group, 33% of people had a relapse or left the study.
Looking only at relapses (not counting people who left the study for other reasons), 56% of people on placebo had a relapse, compared to 33% on low-dose Hizentra and 19% on high-dose Hizentra.
Your results may differ from what was seen in clinical studies.
Are There Additional Potential Benefits of Hizentra Based on Studies?
The PATH study also looked at other measures of nerve and muscle function, though these weren't the study's main goal, so they're considered more exploratory.
Compared with the placebo group, people in both Hizentra groups had smaller declines (or in some cases, improvements) in:
- Grip strength, measured in each hand with a handheld device
- A muscle strength score added up across several muscle groups
- A disability scale that asks about everyday activities and social participation
People taking Hizentra also generally kept more stable levels of IgG in their blood during the study, while IgG levels declined in those in the placebo group.
Your results may differ from what was seen in clinical studies.
Is There Longer-Term Data on Hizentra for CIDP?
After the 24-week PATH study ended, many participants chose to continue into a longer, open-label extension study, meaning everyone knew they were getting Hizentra and no one received a placebo. This extension study followed 82 people for an additional 48 weeks.
In the extension study, people who stayed on the higher 0.4 g/kg dose had a lower relapse rate (about 10%) than those on the lower 0.2 g/kg dose (about 48%). Some participants who relapsed after being switched to the lower dose were switched back up to the higher dose, and most of them (92%) recovered. This suggests that if a relapse happens after a dose is lowered, going back to a higher dose can often help.
Even so, roughly two-thirds of people who finished the original PATH study without relapsing on either dose stayed relapse-free after being switched to the lower dose in the extension study. This means a lower maintenance dose can work well for some people, even though the higher dose showed a lower overall relapse rate across the whole group.
Your results may differ from what was seen in clinical studies. Always check with your health care provider before making adjustments to your dose.
What Do I Need to Do to Get Hizentra?
Hizentra requires a prescription, and it's typically prescribed by a neurologist or another health care provider experienced in treating CIDP. Because it's made from donated human plasma, your health care provider or specialty pharmacy will help coordinate getting your supply, including the infusion pump and other supplies you'll need to infuse it at home.
Is There Any Cost Assistance Available for Hizentra?
CSL Behring, the maker of Hizentra, offers a program that may help reduce your out-of-pocket costs for Hizentra, depending on your insurance situation. A patient support program can also help with questions about insurance coverage and connecting you with infusion training. Ask your health care provider's office or visit the Hizentra website to learn more, or call 877-355-4447 to speak with a representative.
