Efgartigimod for Guillain–Barré syndrome: a retrospective analysis of efficacy and safety

Abstract

Background:

Guillain–Barré syndrome (GBS) is an acute autoimmune neuropathy with limited effective treatments. Efgartigimod, a neonatal Fc receptor (FcRn) antagonist, may offer a novel treatment by reducing pathogenic immunoglobulin G.

Objectives:

To evaluate the efficacy, safety, and immunological effects of efgartigimod in patients with GBS.

Design:

A retrospective, observational, monocentric study.

Methods:

The study included 36 patients with GBS who received efgartigimod treatment. Efficacy was evaluated using the GBS-Disability Scale (GBS-DS) and Medical Research Council (MRC) scores over 8 weeks. Additionally, exploratory lymphocyte subset analysis was conducted on 13 patients before and after treatment.

Results:

Patients were stratified into those receiving efgartigimod as first-line therapy (n = 17) and as escalation therapy after intravenous immunoglobulin or plasma exchange (n = 19). Both cohorts showed significant and sustained clinical improvement over 8 weeks (p < 0.05). More importantly, the first-line cohort demonstrated a more rapid initial response, with a significantly greater reduction in GBS-DS score (ΔGBS-DS: 2.0 vs 0.0 at week 1, p = 0.003) and increase in MRC score (ΔMRC: 9.0 vs 6.0, p = 0.016) compared to the escalation cohort. This led to a higher percentage of achieving a favorable outcome (GBS-DS ⩽2) and a shorter median time to this outcome (6 vs 25 days, p < 0.001) in the first-line cohort. Regression analysis within the entire cohort confirmed that greater baseline severity and need for mechanical ventilation were associated with a longer time to favorable outcome. Exploratory analysis suggested a decrease in the proportions of CD3+CD4+ and CD4+HLA-DR+ T cells following efgartigimod treatment. Only two mild adverse events were reported.

Conclusion:

Efgartigimod shows efficacy as both a rapid-onset first-line therapy and a rescue option for refractory GBS, with a favorable safety profile and potential immunomodulatory effects, supporting further prospective evaluation.

Plain language summary

Testing a new drug (efgartigimod) for Guillain-Barré syndrome: does it improve recovery and is it safe?

Guillain-Barré syndrome (GBS) is a rare disorder where the body’s immune system attacks its own nerves, often leading to severe muscle weakness or paralysis. Current treatments don’t work well for everyone and may carry certain risks. In this study, researchers tested a new drug called efgartigimod, which works by quickly removing harmful antibodies from the blood. The study looked back at 36 adults with GBS who received efgartigimod. Seventeen received it as their first treatment, and 19 received it after standard therapies didn’t work well enough. Over eight weeks, both groups improved significantly in muscle strength and mobility. Importantly, patients who got efgartigimod first improved much faster—many began recovering within the first week and could walk independently in just 6 days on average, compared to 25 days for those who switched to it later. The drug was also very safe: only two mild, temporary side effects (a rash and a headache) were reported. Additional tests in a small group of patients suggested the drug may also calm down overactive immune cells, hinting at a broader mechanism of action. These findings indicate that efgartigimod could be both a fast-acting first-choice treatment and a rescue option for difficult-to-treat GBS. More research in larger trials is now needed to confirm these encouraging results.

Introduction

Guillain–Barré syndrome (GBS) is an acute immune-mediated neuropathy characterized by the production of pathogenic immunoglobulin G (IgG) autoantibodies that target peripheral nerve components, including gangliosides and nodal/paranodal proteins. ¹ These autoantibodies trigger complement activation, macrophage infiltration, and subsequent nerve damage, leading to rapidly progressive muscle weakness and sensory disturbances.^1,2 Currently, standard immunomodulatory therapies for GBS primarily include intravenous immunoglobulin (IVIg) and plasma exchange (PE), which aim to neutralize or remove autoantibodies from circulation.^3,4 Despite their established efficacy, at least 20% of patients treated with either IVIg or PE may exhibit no response, a partial response, or even clinical deterioration.^2,5 Moreover, both IVIg and PE are associated with severe adverse effects, such as myocardial infarction and renal failure, and their use is limited by factors such as increased serum viscosity with IVIg and the requirement for specialized equipment with PE. ⁴ Consequently, there remains a significant unmet need for more effective, targeted, and well-tolerated therapies for GBS that can be applied to a broader patient population.

Efgartigimod is a human IgG1-derived Fc fragment engineered to competitively inhibit the neonatal Fc receptor (FcRn), thereby accelerating the degradation of pathogenic IgG autoantibodies.^6,7 Accumulating evidence has demonstrated its favorable efficacy and safety profile in IgG-mediated autoimmune disorders, including myasthenia gravis (MG), myositis, neuromyelitis optica (NMO), and chronic inflammatory demyelinating polyradiculoneuropathy.^7,8 Notably, emerging case reports have suggested the therapeutic potential of efgartigimod as monotherapy for GBS, with observed rapid improvement in muscle strength. ⁹ Furthermore, it may provide clinical benefits for GBS patients exhibiting suboptimal or no response to IVIg or PE.^10,11 However, the comprehensive efficacy and safety profile of efgartigimod in the treatment of GBS remains to be fully elucidated. This study aims to evaluate the role of efgartigimod in the management of GBS through a descriptive analysis of a large cohort of patient records from our institution, focusing on its efficacy, influencing factors, and recovery timeline. Additionally, we analyzed dynamic changes in lymphocyte subsets before and after efgartigimod administration to explore its potential immunomodulatory effects in restoring immune homeostasis.

Methods

Standard protocol approvals

This retrospective study was approved by the Ethics Committee of the First Affiliated Hospital of Zhengzhou University (Approval No. 2024-KY-1766-004) on January 3, 2025. The requirement for additional informed consent was formally waived for this analysis of anonymized clinical data. All patients had provided written consent for the off-label use of efgartigimod, which detailed its experimental nature, benefits, and risks.

Patients and study design

This manuscript was prepared in accordance with the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines, as detailed in the STROBE checklist provided in the Supplemental Materials. In this retrospective observational single-center study, we reviewed the clinical records of patients diagnosed with GBS at the First Affiliated Hospital of Zhengzhou University from January 2024 to April 2025. All patients received efgartigimod at a dose of 10 mg/kg administered once weekly, a regimen selected to achieve rapid and sustained IgG reduction in autoimmune disease.^7,8 Among the 17 patients receiving first-line efgartigimod, the primary reasons were: mitigation of risks associated with standard therapies (n = 11), such as severe IVIg intolerance or hemodynamic instability contraindicating PE; and the pursuit of rapid efficacy in hyperacute, severe cases (n = 6) with fulminant progression. Inclusion criteria were as follows: (1) confirmed diagnosis of GBS based on established clinical criteria, ¹ including acute flaccid areflexic quadriparesis, albuminocytologic dissociation in cerebrospinal fluid (CSF), and characteristic nerve conduction findings; (2) age at onset ⩾18 years; and (3) treatment with efgartigimod at a dose of 10 mg/kg administered once weekly. Exclusion criteria included: (1) insufficient clinical data; (2) presence of other identifiable neuropathies; (3) coexisting severe systemic conditions, including other autoimmune diseases, severe hepatic or renal dysfunction, cardiovascular or cerebrovascular diseases, or septic shock; and (4) follow-up duration less than 8 weeks. Additionally, an exploratory analysis of peripheral blood lymphocyte subsets was performed using data from 13 patients, collected before and after efgartigimod treatment. Lymphocyte subset analysis was performed within 0–2 days prior to and 12–14 days following initiation of efgartigimod therapy. The patient selection process is summarized in Figure 1.

Figure 1.

Flowchart of patient selection.

Data collection

Demographic and clinical data were extracted from our institution’s standardized electronic medical record system, which incorporates predefined clinical assessment schedules and safety monitoring protocols for the routine care of patients with GBS. The collected variables included age at onset, sex, initial symptoms, antecedent infections, disease duration, nerve conduction velocity findings, GBS classification based on motor nerve conduction criteria, ¹² blood neutrophil–lymphocyte ratio (NLR), monocyte–lymphocyte ratio (MLR), serum antiganglioside IgG antibody profiles (including GM1, GM2, GM3, GM4, GD1a, GD1b, GD2, GD3, GT1a, GT1b, GQ1b, and sulfatide), CSF findings, treatment modalities, and time interval from symptom onset to treatment initiation.

Complete blood counts, including neutrophil, lymphocyte, and monocyte counts, were obtained using a Mindray SC-120 hematology analyzer (Mindray, Shenzhen, China). Flow cytometry (DxFLEX Flow Cytometer; Beckman Coulter, Brea, CA, USA) was employed to determine the percentages of various lymphocyte subsets, including CD3+ T cells, CD3+CD45RA+ T cells, CD3+CD45RA− T cells, CD3+CD4+ T helper (Th) cells, CD4+CD28+ Th cells, CD4+HLA-DR+ Th cells, CD4+CD38+ Th cells, CD3+CD8+ T suppressor (Ts) cells, CD8+CD28+ Ts cells, CD8+HLA-DR+ Ts cells, CD8+CD38+ Ts cells, CD4+CD8+ double-positive T cells, CD4–CD8− double-negative T cells, CD3–CD19+ B cells, and CD3–CD56+ natural killer cells. Serum IgG concentrations were quantified by immunoturbidimetry. All laboratory analyses were performed by the clinical laboratory of The First Affiliated Hospital of Zhengzhou University.

Efficacy assessments

Disease severity was assessed using the 0–6 GBS-Disability Scale (GBS-DS) scores and the Medical Research Council (MRC) scores (sum of scores from 12 muscle groups with a total score of 60).^13,14 The GBS-DS and MRC scores were extracted from medical records at predefined time points: baseline (the start of efgartigimod treatment) and weeks 1, 2, 3, 4, and 8 posttreatment. The primary outcome was the proportion of patients who achieved a favorable outcome, defined as the ability to walk independently for 10 m (GBS-DS score ⩽2), within the 8-week study period.^3,15 Secondary outcomes included the time to achieve a favorable outcome, which was determined in days based on the first documented date in the clinical record that the patient met the criteria (GBS-DS score ⩽2), as well as changes in GBS-DS and MRC scores from baseline to weeks 1, 2, 3, 4, and 8.

Safety assessments

Safety evaluations involved monitoring for adverse events (AEs) throughout the study period. Monitored AEs included headache, fatigue, nausea, fever, diarrhea, and respiratory or urinary tract infections, which are commonly associated with the treatment based on existing literature.^6,7 AEs were categorized as mild if they did not necessitate changes in treatment dosage or frequency, and as serious if they resulted in treatment discontinuation, caused permanent impairment, or involved life-threatening complications or death. ¹⁶ In addition, alterations in laboratory parameters were evaluated at each visit, including white blood cell (WBC) count, alanine transaminase (ALT), creatinine, low-density lipoprotein cholesterol (LDL-C), total cholesterol (TC), and albumin levels. ¹⁷

Statistical analysis

Descriptive data are presented as mean ± standard deviation (SD) or median (interquartile range (IQR)) for continuous variables and as frequencies (%) for categorical variables. Categorical variables were compared between the two groups using the Chi-square test or Fisher’s exact test, while continuous variables were compared using the Mann–Whitney U test or unpaired t test. Changes in GBS-DS and MRC scores from baseline at each time point were evaluated using the Wilcoxon signed-rank test. Correlation analysis was conducted using Spearman’s correlation coefficient. Survival curves were calculated using Kaplan–Meier curves and compared using the log-rank test. Univariate Cox regression analysis was performed to identify factors associated with the time to a favorable outcome (GBS-DS ⩽2). All statistical analyses were performed using SPSS version 22.0 (SPSS Inc., Chicago, IL, USA), GraphPad Prism version 9.3.1 (GraphPad Software, Boston, MA, USA), and R version 4.2.3 (R Foundation for Statistical Computing, Vienna, Austria). A two-sided p value <0.05 was considered statistically significant.

Results

Clinical characteristics

A total of 36 patients with GBS who received efgartigimod treatment were enrolled and stratified into two cohorts based on treatment sequence: 17 patients (47.2%) received efgartigimod as first-line monotherapy, while 19 patients (52.8%) received it as escalation therapy after insufficient response to prior IVIg (n = 18) or PE (n = 1). The baseline characteristics of the total cohort are summarized in Supplemental Table 1. As shown in Table 1, the escalation therapy cohort had significantly greater disease severity at baseline compared to the first-line cohort, as evidenced by higher GBS-DS scores (median (IQR): 5.0 (4.0–5.0) vs 4.0 (3.0–4.0); p = 0.011), lower MRC sum scores (22.0 (14.0–32.0) vs 33.0 (25.5–36.5); p = 0.025), and a greater proportion requiring mechanical ventilation (31.6% vs 0.0%; p = 0.011). In addition, patients in the escalation cohort were younger (41.6 (30.2–58.4) vs 57.7 (48.8–75.7) years; p = 0.013) and exhibited a higher NLR (4.9 (2.8–12.4) vs 2.7 (1.9–3.8); p = 0.015). No significant differences were observed between the cohorts regarding sex, antecedent illness, GBS electrophysiological subtypes, CSF protein levels, or the time from onset to efgartigimod initiation (all p > 0.05).

Table 1.

Comparison of baseline characteristics between GBS patients receiving efgartigimod as first-line monotherapy and as escalation therapy.

Variables	First-line monotherapy (n = 17)	Escalation therapy (n = 19)	p Value
Age at disease onset, years	57.7 (48.8, 75.7)	41.6 (30.2, 58.4)	0.013*
Sex			0.985
Female	8 (47.1%)	9 (47.4%)
Male	9 (52.9%)	10 (52.6%)
Time from onset to efgartigimod administration, days	13.0 (9.0, 23.0)	19.0 (13.0, 23.0)	0.357
Antecedent illness			0.790
No	7 (41.2%)	7 (36.8%)
Yes a	10 (58.8%)	12 (63.2%)
GBS subtypes			0.492
AIDP	10 (58.8%)	9 (47.4%)
Non-AIDP b	7 (41.2%)	10 (52.6%)
Complete blood count before efgartigimod administration
NLR	2.7 (1.9, 3.8)	4.9 (2.8, 12.4)	0.015*
MLR	0.3 (0.2, 0.4)	0.4 (0.3, 0.5)	0.211
Serum antiganglioside antibody			0.234
Negative	7 (53.8%)	4 (30.8%)
Positive	6 (46.2%)	9 (69.2%)
NCV findings			0.492
Demyelinated	10 (58.8%)	9 (47.4%)
Non-demyelinated c	7 (41.2%)	10 (52.6%)
CSF protein, mg/dL	61.6 (42.3, 91.9)	62.1 (43.1, 96.8)	0.912
MV involved intubation or tracheostomy	0 (0.0%)	6 (31.6%)	0.011*
Numbers of efgartigimod administrations			0.215
2	7 (41.2%)	4 (21.2%)
3	5 (29.4%)	4 (21.2%)
4	5 (29.4%)	11 (57.9%)
Disease severity at baseline
GBS-DS scores	4.0 (3.0, 4.0)	5.0 (4.0, 5.0)	0.011*
MRC scores	33.0 (25.5, 36.5)	22.0 (14.0, 32.0)	0.025*
GBS-DS score ⩽2	2 (11.8%)	2 (10.5%)	0.906

Data are given as median (IQR) or n (%).

^aAntecedent illness (Yes) included respiratory tract infection, diarrhea, and other events.

^bNon-AIDP included AMAN, AMSAN, MFS, and equivocal subtypes.

^cNondemyelinating patterns include axonal, inexcitable, equivocal, and normal patterns.

^*A two-sided p value <0.05 was considered statistically significant, with significant results highlighted in bold within the table.

AIDP, acute inflammatory demyelinating polyneuropathy; AMAN, acute motor axonal neuropathy; AMSAN, acute motor and sensory axonal neuropathy; CSF, cerebrospinal fluid; GBS, Guillain–Barré syndrome; GBS-DS, Guillain–Barré Syndrome Disability Scale; IQR, interquartile range; MFS, Miller–Fisher syndrome; MLR, monocytes-to-lymphocyte ratio; MRC, Medical Research Council; MV, mechanical ventilation; NCV, nerve conduction velocity; NLR, neutrophil-to-lymphocyte ratio.

Efficacy of efgartigimod

Patients in both treatment cohorts demonstrated significant functional improvement over the 8-week follow-up period (Figure 2 and Supplemental Table 2). In the first-line monotherapy cohort, the median GBS-DS scores decreased significantly from 3.0 (IQR: 2.0–4.0) at baseline to 1.0 (IQR: 1.0–1.5) at week 8, while MRC sum scores increased from 33.0 (25.5–36.5) to 56.0 (50.0–58.0; all p < 0.05; Figure 2(a)). Similarly, in the escalation therapy cohort, the median GBS-DS scores improved significantly from 5.0 (4.0–5.0) to 2.0 (1.0–3.0), and MRC scores increased from 22.0 (14.0–32.0) to 52.0 (42.0–56.0; all p < 0.05; Figure 2(b)).

Figure 2.

Efficacy of efgartigimod within each treatment cohort. (a) Longitudinal changes in GBS-DS and MRC scores from baseline in the first-line monotherapy cohort (n = 17). (b) Longitudinal changes in GBS-DS and MRC scores from baseline in the escalation therapy cohort (n = 19). The Wilcoxon signed-rank test was used to evaluate the changes in GBS-DS and MRC scores compared to the last follow-up.

*p < 0.05.

GBS-DS, Guillain–Barré Syndrome Disability Scale; MRC, Medical Research Council.

Despite improvement in both groups, the first-line monotherapy cohort demonstrated a significantly more rapid initial response (Figure 3 and Supplemental Table 3). At week 1, the reduction in GBS-DS score from baseline (ΔGBS-DS) was markedly greater in the first-line cohort compared to the escalation cohort (2.0 (1.0–2.0) vs 0.0 (0.0–1.0); p = 0.003; Figure 3(a)). Concurrently, the improvement in MRC score (ΔMRC) was also greater in the first-line cohort (9.0 (7.0–13.0) vs 6.0 (3.0–9.0); p = 0.016; Figure 3(b)). This accelerated recovery led to a consistently higher proportion of patients achieving a favorable outcome (GBS-DS ⩽2) in the first-line cohort throughout follow-up (Figure 4 and Supplemental Table 3), and a significantly shorter median time to this outcome (6 vs 25 days in the escalation cohort; p < 0.001).

Figure 3.

Comparison of treatment response between the first-line and escalation therapy cohorts. (a) Comparison of the ΔGBS-DS between two groups at each follow-up. (b) Comparison of the ΔMRC between two groups at each follow-up. The Mann–Whitney U test was used to compare ΔGBS-DS and ΔMRC at each time point between two groups.

*p < 0.05.

ΔGBS-DS, change in Guillain–Barré Syndrome Disability Scale scores from baseline; ΔMRC, change in Medical Research Council scores from baseline.

Figure 4.

Time to achieve a favorable outcome (GBS-DS ⩽2) stratified by treatment cohort.

GBS-DS, Guillain–Barré Syndrome Disability Scale.

To identify general prognostic factors within the entire population treated with efgartigimod, a univariate Cox regression analysis was performed (Table 2). The analysis revealed that greater baseline disease severity, indicated by a higher GBS-DS score (hazard ratio (HR) = 0.136, p < 0.001) or a lower MRC score (HR = 1.127, p < 0.001), was strongly associated with a longer time to achieve a favorable outcome. Additionally, the necessity for mechanical ventilation (HR = 0.101, p = 0.002) and a history of prior IVIg or PE treatment (HR = 0.281, p = 0.002) were significant negative predictors.

Table 2.

Univariate Cox regression analysis of factors associated with time to favorable outcome (GBS-DS ⩽2).

Variables	HR (95% CI)	p Value
Demographic and clinical factors
Age at disease onset, years	1.005 (0.988, 1.023)	0.558
Sex
Female	1 (Reference)
Male	0.658 (0.324, 1.335)	0.246
Antecedent illness
No	1 (Reference)
Yes	0.658 (0.324, 1.335)	0.228
GBS subtypes
Non-AIDP	1 (Reference)
AIDP	1.409 (0.687, 2.887)	0.349
Laboratory parameters
NLR	0.950 (0.902, 1.000)	0.052
MLR	0.624 (0.182, 2.135)	0.453
Serum antiganglioside antibody a
Negative	1 (Reference)
Positive	0.934 (0.402, 2.169)	0.874
CSF protein, mg/dL	1.002 (0.994, 1.011)	0.593
Disease severity and treatment
Baseline GBS-DS scores	0.136 (0.067, 0.276)	<0.001*
Baseline MRC scores	1.127 (1.073, 1.184)	<0.001*
MV involved intubation or tracheotomy
No	1 (Reference)
Yes	0.101 (0.023, 0.445)	0.002*
IVIg or PE treatment before efgartigimod administration	0.281 (0.127, 0.622)	0.002*
Time from onset to efgartigimod administration, days	0.959 (0.909, 1.012)	0.129
Numbers of efgartigimod administration		0.012*
2	1 (Reference)
3	3.833 (1.554, 9.451)	0.004*
4	1.467 (0.591, 3.643)	0.409
Numbers of efgartigimod administration		0.012*
2	1 (Reference)
3	3.833 (1.554, 9.451)	0.004*
4	1.467 (0.591, 3.643)	0.409

^aAnalysis of patients who underwent the respective tests.

^*p < 0.05.

AIDP, acute inflammatory demyelinating polyneuropathy; CI, confidence interval; CSF, cerebrospinal fluid; GBS-DS, GBS-Disability Scale; HR, hazard ratio; IVIg, intravenous immunoglobulin; MLR, monocytes-to-lymphocyte ratio; MRC, Medical Research Council; MV, mechanical ventilation; NLR, neutrophil-to-lymphocyte ratio; PE, plasma exchange.

Exploratory analysis of lymphocyte subset changes following efgartigimod treatment

Given the small sample size and the exploratory nature of this component, lymphocyte subset data were available for a subgroup of patients (n = 13). The baseline characteristics and a detailed history of all immunotherapies received by this subgroup are provided in Supplemental Table 4. A heatmap was used to assess the correlation between the disease severity of GBS and lymphocyte subsets as well as laboratory parameters (Figure 5). The results indicated a positive correlation between the NLR and GBS-DS scores (r = 0.77, p = 0.002), and a negative correlation between NLR and MRC scores (r = −0.58, p = 0.038). However, no significant associations were observed between disease severity (as assessed by the GBS-DS or MRC scores) and specific lymphocyte subsets, MLR, serum IgG levels, or CSF protein concentration. Exploratory analysis of lymphocyte subsets suggested a decreasing trend in the proportions of CD3+CD4+ and CD4+HLA-DR+ T cells following efgartigimod treatment, with detailed results provided in the Supplemental Figures 1 and 2 and Supplemental Table 5.

Figure 5.

Correlations of lymphocyte subsets and laboratory parameters with disease severity in GBS. Spearman correlation analysis was used to assess the correlation between disease severity and lymphocyte subsets and laboratory parameters in GBS patients.

*p < 0.05, **p < 0.01.

GBS, Guillain–Barré syndrome; GBS-DS, GBS-Disability Scale; IgG, immunoglobulin G; MLR, monocytes-to-lymphocyte ratio; MRC, Medical Research Council; NK, natural killer; NLR, neutrophil-to-lymphocyte ratio; Th, T helper; Ts, T suppressor.

Safety of efgartigimod

Only two mild AEs were reported; both occurred during the efgartigimod infusion and were transient. One patient developed a localized erythematous rash on the anterior neck, while the other experienced a mild headache. The overall incidence of AEs within the 8-week follow-up period was 5.6%. No infections or serious AEs (SAEs) were observed throughout the study period. Furthermore, no clinically relevant changes were noted in WBC count, ALT, creatinine, LDL-C, TC, and albumin levels during the 8-week follow-up (Supplemental Figure 3).

Discussion

Accumulating evidence suggests that inhibition of the FcRn represents a promising therapeutic strategy for IgG-mediated autoimmune disorders.^6,8 Our study supports this by demonstrating that efgartigimod was both effective and well-tolerated in GBS, while also providing exploratory data on associated changes in lymphocyte subsets. Notably, our findings extend prior knowledge by delineating the distinct clinical profiles and treatment responses of two key patient cohorts.

Our study demonstrates that efgartigimod treatment led to significant and sustained clinical improvement in patients with GBS, consistent with emerging evidence for FcRn inhibition in immune-mediated neurological disorders.^17,18 The clinical response, however, differed meaningfully based on treatment sequence, revealing two distinct therapeutic profiles. Patients receiving efgartigimod as first-line monotherapy exhibited a particularly rapid response, achieving a favorable outcome in a median of 6 days. Conversely, in the escalation therapy cohort, efgartigimod also induced significant improvement in patients with more severe baseline disease who had previously failed IVIg/PE. The clinical recovery commencing shortly after efgartigimod initiation, following a median 12-day interval from prior standard therapy, is best attributed to efgartigimod itself, as it falls outside the conventional window for IVIg response.^1,4,5 This positions efgartigimod as both a rapid-onset first-line option and a viable rescue therapy, especially for refractory cases. ¹⁰ The observed slower recovery in patients requiring mechanical ventilation or more efgartigimod infusions was substantiated by Cox regression, which identified greater baseline disease severity as the primary driver of delayed improvement.^5,19

FcRn has emerged as a promising therapeutic target for autoimmune diseases due to its role in modulating both humoral and cellular immunity. ²⁰ In our study, exploratory analysis in a subgroup of patients revealed shifts in lymphocyte subsets, including CD4+ T cells, following efgartigimod treatment. While prior reports suggest that FcRn inhibition can influence immune activation,^9,21,22 and CD4+ T cells are implicated in GBS pathogenesis,^23,24 the limited sample size and retrospective design of our study preclude definitive conclusions regarding a direct, causal drug effect. Therefore, these observations should be considered hypothesis-generating. The potential for efgartigimod to modulate cellular immunity in GBS remains an open question that warrants investigation in future prospective studies with dedicated immunological endpoints.

Efgartigimod demonstrated a favorable safety profile in our study. Only two mild AEs were reported during the infusion process, and no SAEs or infections occurred during the 8-week follow-up. These findings align with the safety profile observed in previous studies of efgartigimod in MG, NMO spectrum disorder, and immune thrombocytopenia, where the drug demonstrated a favorable safety profile even with repeated administration.^17,25,26 Importantly, no significant alterations were observed in key laboratory parameters, including liver and kidney function tests, lipid profile, and WBC counts. Although FcRn inhibition carries a potential risk of hypogammaglobulinemia, our data support the short-term safety of efgartigimod for GBS.

This study has several limitations. First, the retrospective design and relatively small sample size, especially in the lymphocyte subset analysis, may limit the generalizability of our findings. Second, the follow-up period was limited to 8 weeks; therefore, long-term outcomes and relapse rates remain unknown. Third, the lack of a contemporaneous, matched control group for both the first-line and escalation therapy cohorts precludes direct comparative effectiveness conclusions against standard care. Finally, the exploratory analysis of lymphocyte subsets was conducted in a small subgroup and should therefore be interpreted as hypothesis-generating; its findings require validation in larger, prospective studies with functional correlates.

Conclusion

This study demonstrates that efgartigimod is an effective and well-tolerated treatment for GBS, supporting a dual clinical role: as a rapid-onset first-line therapy and an effective rescue option for refractory disease. Exploratory data suggesting a reduction in activated CD4+ T cells point to potential immunomodulatory actions beyond IgG clearance, warranting further investigation. These results strongly justify prospective randomized controlled trials to define the optimal place and mechanism of efgartigimod in GBS therapy.