Intravenous immunoglobulin (IVIG) is a compound that consists of immune globulins (immune proteins) that are usually administered into the bloodstream. It is used to treat patients with severe or rapidly worsening myasthenia gravis (MG).
IVIG is available as Gamunex-C (IGIV-C, sold by Grifols); Venuglobulin IH 5% (developed by Benesis, a subsidiary of Mitsubishi Tanabe Pharma); and Hizentra (SCIg, by CSL Behring). Hizentra is administered via injections beneath the skin, not directly into the bloodstream.
How IVIG works
Autoantibodies in the blood that target acetylcholine receptors are the key problem in myasthenia gravis. IVIG consists of immune globulins collected from donors and acts to destroy and neutralize these autoantibodies in the bloodstream and block the production of new autoantibodies.
It is usually used as part of what is called a rapid induction therapy. This is a form of treatment meant to quickly suppress the immune system and is typically used in myasthenic crisis (the sudden and severe worsening of disease symptoms); before a patient undergoes surgery; as a temporary medication while a patient transitions to other therapies that suppress the immune system; or for those with severe MG who don’t respond to other treatments.
IVIG is usually given slowly over a few hours, with multiple infusions given over a few days.
IVIG in clinical trials
Randomized controlled trials investigating IVIG for worsening symptoms of MG produced mixed results. A review of seven such trials found that while some studies showed that patients benefited from IVIG treatment, others did not. Still, IVIG is an accepted treatment option for myasthenic crises.
Hizentra is currently the focus of a Phase 3 clinical trial (NCT027742390) where patients with worsening MG are treated with increasing doses of SCIg over one month. The trial aims to assess potential improvements in symptoms, safety, and patient satisfaction. It is currently recruiting participants at centers in Canada and is expected to be completed in in December 2018.
A Phase 2 clinical trial (NCT02100969), where Hizentra is given once a week for three months at variable rates and doses (depending on how each participant tolerates the drug) to evaluate its effects on MG symptoms, is still active but no longer recruiting participants. The trial is scheduled to be complete by December 2018.
In the Phase 2 trial, patients with generalized myasthenia gravis on corticosteroids will initially receive a single 2 g/kg dose and two 1 g/kg doses of IVIG-C, followed by a slow decrease of their corticosteroid doses over nine months while continuously receiving regular doses of 1 g/kg of IVIG-C. It is currently recruiting participants in the U.S. and Europe and is expected to end in August 2018.
The Phase 3 trial involves two 1 g/kg doses of IGIV-C given over two days to patients who have worsening symptoms of MG. IGIV-C’s effects on symptoms improvement will be assessed over the following month. A total of 50 patients are targeted, with the trial carried out in centers in Argentina, Canada, Europe, and South Africa.
A Phase 2 trial of IGIV-C is also complete (NCT02473952). Here, one dose of 1 g/kg of IGIV-C or a placebo was given to participants with MG every three weeks for 21 weeks. The primary endpoint was to determine whether IGIV-C was able to improve the symptoms of MG. The trial was completed in January 2018, but results have not yet been made available.
A Phase 4 trial (NCT01179893) compared the effects of 2 g/kg of IVIG to plasma exchange (a treatment where a patient’s blood plasma which contains autoantibodies is removed and replaced by fresh, donated plasma). The results showed that both treatments were able to improve symptoms of myasthenia gravis. The trial took place at the University Health Network in Toronto, Canada.
IVIG may cause headaches, body aches, and chills during the infusion. Fever, nausea, and lethargy may persist for 24 hours after the infusion. Rare and more severe reactions include migraines, severe allergic reactions, skin reactions, brain inflammation (aseptic meningitis) and blood clots.
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