A retrospective survival analysis of relapse rate in pediatric and adult autoimmune encephalitis (P4-5.003)

Objective:

To investigate relapse rate in pediatric and adult autoimmune encephalitis (AE)

Background:

Prior observational studies for AE have mostly focused on outcomes following acute immunotherapies. Varying relapse rates are reported among the different autoantibodies with limited evidence on long-term immunotherapy use after acute treatment and its associated clinical outcomes.

Design/Methods:

We conducted a retrospective study of consecutive patients meeting clinical criteria for AE evaluated at UC San Diego and Rady Children's Hospital from January 2007 to November 2021. Survival analysis and cox multivariable regression models were employed to evaluate relapse risk using rituximab exposure as a time-dependent variable.

Results:

A total of 35 pediatric (29 seropositive, 6 seronegative) and 75 adult (57 seropositive, 18 seronegative) patients were included in the study. The most common antibody subtype in both cohorts was anti-NMDA receptor (NMDAR). Relapses occurred in 31% of pediatric seropositive, 50% of pediatric seronegative, 38% of adult seropositive, and 27% of adult seronegative cases. Times to first relapse (TTFR) were 10.3 ± 7.4 months (pediatric seropositive), 6.9 ± 4.3 months (pediatric seronegative), 15.4 ± 29.3 months (adult seropositive), and 7.8 ± 6.5 months (adult seronegative). Combining pediatric and adult data, and adjusting for age and sex, rituximab use was associated with 74% lower hazard to relapse (HR 0.26, 95% CI 0.09 – 0.75, p= 0.01) for TTFR and the adjusted HR for rituximab use for recurring relapses was 0.36 (95% CI 0.15 – 0.87, p=0.03). The effect of rituximab was stronger for non-NMDA encephalitis than anti-NMDAR encephalitis (HR 0.39, 95% CI 0.16 – 0.96 vs HR 0.49, 95% CI 0.11 – 2.30).

Conclusions:

Relapses occur in approximately one-third of pediatric and adult patients with AE, although less frequent in anti-NMDARE. Our data demonstrate a substantial benefit of rituximab use for reducing relapse rate as acute or chronic immunotherapy. Disclosure: Dr. Yang has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Neurology Live. Dr. Yang has received research support from United Mitochondrial Disease Foundation. Miss Liu has received personal compensation for serving as an employee of SpineX Inc.. Dr. Nguyen has nothing to disclose. Dr. Dunn-Pirio has nothing to disclose. Dr. Graves has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Genentech. Dr. Graves has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for TG Therapeutics. Dr. Graves has received personal compensation in the range of $5,000-$9,999 for serving as an Editor, Associate Editor, or Editorial Advisory Board Member for ACTN. The institution of Dr. Graves has received research support from Biogen. The institution of Dr. Graves has received research support from Octave. The institution of Dr. Graves has received research support from Sanofi. The institution of Dr. Graves has received research support from EMD Serono.