IVIG Results in Improved Response Rate in Patients with Autoimmune Encephalitis

In a new study, intravenous immune globulin (IVIG) improved clinical response rates in patients with autoimmune encephalitis (AE) who had inadequate response to steroid pulse therapy.

The Phase III double-blind, active-controlled study (NCT05177939), investigators enrolled 40 patients with AE who failed to respond adequately to steroid pulse therapy. Participants were randomized 1:1 to receive either IVIG or continued steroid pulse therapy, with the primary endpoint defined as a ≥40 percent improvement on the Clinical Assessment Scale in Autoimmune Encephalitis (CASE) at week 4.

Findings showed that among patients with cell-surface antigen antibodies — the primary analysis population — response rates were 57.1 percent in the IVIG group compared with 0 percent in the control group. In the broader full analysis set (n=20 per group), response rates were 50.0 percent with IVIG versus 25.0 percent with continued steroid therapy. Secondary outcomes, including changes in modified Rankin Scale (mRS) scores, were consistent with the primary findings and supported improved functional outcomes in the IVIG-treated cohort.

Safety findings were comparable between groups, with most adverse events reported as mild to moderate in severity. According to the researchers, these results suggest IVIG may offer a clinically meaningful benefit in patients with AE who do not respond to corticosteroids alone, a population in which treatment decisions are often guided by limited prospective data.