Development and Validation of a Nomogram to Predict Minimal Symptom Expression in AChR+ gMG Patients Undergoing Efgartigimod Therapy.

BACKGROUND

Efgartigimod has emerged as an effective treatment option for acetylcholine receptor antibody-positive generalized myasthenia gravis (AChR+ gMG). This study aimed to develop and validate a predictive nomogram to evaluate the achievement of Minimal Symptom Expression (MSE) in AChR+ gMG patients following efgartigimod treatment.

METHODS

We retrospectively reviewed 119 patients with AChR+ gMG who received at least one cycle of efgartigimod and had ≥ 12 weeks of follow-up. Clinical response was defined as MSE, referring to an MG-ADL score of 0 or 1 within 4 weeks of treatment initiation and sustained for ≥ 4 consecutive weeks. Independent predictors of MSE were identified using multivariable logistic regression and incorporated into a nomogram. Model performance was assessed by discrimination (AUC-ROC) and calibration, with internal validation performed using bootstrap resampling.

RESULTS

The MSE responder rate was 37.0%. New-onset MG (OR=2.691, p=0.031), thymoma-associated MG (TAMG) (OR=0.209, p=0.027), baseline QMG score (OR=0.888, p=0.007), and the reduction in IgG levels after one treatment cycle (ΔIgG) (OR=1.168, p=0.040) were independently associated with the clinical response. The nomogram demonstrated moderate discrimination, with a bootstrap-corrected AUC of 0.744 (95% CI: 0.732-0.771), indicating stable performance after internal validation.

DISCUSSION: The nomogram indicates that new-onset MG and ΔIgG are associated with a higher probability of achieving MSE, while TAMG and a higher baseline QMG score are linked to poorer outcomes. These findings further support the potential value of early intervention and dynamic IgG monitoring in guiding individualized treatment strategies.

CONCLUSION

By integrating new-onset MG, TAMG, baseline QMG score, and ΔIgG, this nomogram provides an individualized prediction of MSE in AChR+ gMG patients treated with efgartigimod, offering a practical clinical tool to help tailor treatment strategies.