Efgartigimod-rituximab sequential therapy in Anti-NMDAR encephalitis: real-world evidence for a novel salvage-maintenance strategy.

BACKGROUND

A subset of anti-NMDAR encephalitis (NMDARe) patients demonstrate suboptimal response to initial immunotherapies (steroids/intravenous immunoglobulin [IVIg]), which poses significant clinical dilemmas regarding therapeutic escalation. This real-world study retrospectively analyzes salvage immunotherapy outcomes in patients with treatment resistance across acute and maintenance phases.

METHODS

We performed regression analysis to identify risk factors for treatment failure. Comparative assessments were then conducted for acute-phase salvage therapies (therapeutic plasma exchange [TPE], repeated IVIg [reIVIg], cyclophosphamide, rituximab [RTX], and efgartigimod [EFG] + RTX) and maintenance-phase immunotherapies (azathioprine, mycophenolate mofetil [MMF], and repeated RTX [reRTX]), with evaluation of both efficacy and safety profiles.

RESULTS

In this real-world cohort of 219 NMDARe patients, 86 (39.3%) exhibited inadequate response to initial immunotherapies, with status epilepticus identified as an independent predictor of treatment resistance. EFG + RTX showed synergistic acute salvage efficacy, with significantly improved response rates versus reIVIg and cyclophosphamide, though only numerically higher than TPE and RTX monotherapy. The combination therapy also demonstrated statistically significant benefits in terms of response latency, functional recovery and hospitalization duration while maintaining a favorable safety profile. During maintenance phase, reRTX administration showed superior long-term outcomes compared to conventional immunosuppressants (azathioprine or MMF), with reduced relapse rates and better tolerability.

CONCLUSION

These findings provide the first real-world evidence for EFG-RTX sequential therapy benefits in initially unresponsive NMDARe, with observed synergistic effects supported by mechanistic evidence though not formally tested. This novel salvage-maintenance approach demonstrates promising efficacy and safety, warranting validation through larger controlled studies.