Thymic Disease, Autoimmunity, and Neuromuscular Junction Integrity in Myasthenia Gravis (TAILOR-MG)

Thymic Disease, Autoimmunity, and Neuromuscular Junction Integrity in Myasthenia Gravis: An Observational Prospective Translational Cohort Study

The goal of this observational study is to investigate the clinical, immunological, and neuromuscular features associated with the development and progression of myasthenia gravis (MG) in adult patients with thymic abnormalities and/or MG-related antibodies, including individuals with or without clinically manifest disease.

The main questions it aims to answer are:

• Whether integrated clinical, serological, and histopathological profiles are associated with the presence of MG and can predict disease onset or progression
• Wheter systemic immune markers are associated with disease activity, progression, and neuromuscular junction alterations

Participants will:

• Undergo clinical, neurological, and neurophysiological assessments at baseline and during follow-up
• Provide blood samples for serological and immunological analyses
• Provide thymic tissue and residual intercostal muscle samples (when undergoing clinically indicated thymectomy) for research analyses
• Attend follow-up visits at 6, 12, and 18 months
• Record daily symptoms using an electronic patient-reported outcome tool (for participants with MG)

Study Overview

• Status: Not yet recruiting
• Conditions: Thymoma; Myasthenia Gravis Associated With Thymoma; Myasthenia Gravis (MG)

Detailed Description

Myasthenia gravis (MG) is an autoimmune disorder of the neuromuscular junction characterized by fluctuating muscle weakness and fatigability. In most cases, the disease is associated with antibodies directed against the acetylcholine receptor (AChR) and is frequently linked to thymic abnormalities, including thymoma and thymic hyperplasia. Despite the recognized role of the thymus in MG pathogenesis, the mechanisms driving the transition from thymic autoimmunity to clinically manifest disease remain incompletely understood, and reliable biomarkers for disease prediction and monitoring are lacking.

This study is a single-center, prospective, observational translational cohort designed to comprehensively characterize the clinical, neurophysiological, serological, immunological, and histopathological features of patients with thymic abnormalities and/or MG. The study adopts a multimodal approach integrating routine clinical assessments with advanced laboratory and tissue-based analyses, with the aim of identifying biological mechanisms and potential biomarkers associated with MG onset and progression.

A total of 40 adult participants will be enrolled and stratified into four predefined groups:

1. patients with thymoma and MG-related antibodies,
2. patients with other thymic abnormalities and MG-related antibodies,
3. thymoma patients without MG-related antibodies (control group), and
4. patients with established MG without thymic abnormalities. This design enables comparison across different clinical and immunological phenotypes and supports exploratory evaluation of circulating and tissue-based biomarkers.

At baseline, all participants will undergo standardized clinical and neurological evaluation, including validated MG-specific outcome measures, neurophysiological testing (repetitive nerve stimulation and single-fiber electromyography), and blood sampling for serological and immunological analyses. Imaging assessments, including chest CT for thymic characterization and orbital MRI for evaluation of extraocular muscle involvement, will be performed according to clinical indications. Participants will be followed longitudinally for 18 months, with scheduled evaluations at 6, 12, and 18 months. Follow-up assessments will include repeated clinical, neurophysiological, and serological measurements to capture disease evolution over time and to evaluate the relationship between biological markers and clinical outcomes.

In participants undergoing thymectomy as part of standard clinical care, thymic tissue will be collected for routine diagnostic purposes, with additional samples used for research analyses. Residual intercostal muscle tissue obtained within the surgical field will also be collected, without modification of the surgical procedure or additional risk to the patient. These samples will be used to investigate structural and molecular features of the neuromuscular junction, including receptor organization and evidence of immune-mediated damage.

Peripheral blood samples collected at baseline and follow-up visits will be used to characterize systemic immune profiles, including autoantibodies, cytokines, and complement activation products. These data will be integrated with clinical, neurophysiological, and histopathological findings to explore associations with MG onset, severity, and progression.

In participants with established MG, longitudinal symptom monitoring will be performed using an electronic patient-reported outcome tool based on questionnaires routinely used in clinical practice. Patients will record daily symptoms across key domains (ocular, bulbar, respiratory, and limb involvement), enabling high-resolution assessment of symptom fluctuations over time. These data will be compared with clinical outcome measures collected during scheduled visits to evaluate concordance and the potential added value of continuous symptom monitoring.

Overall, this study aims to provide an integrated characterization of MG across clinical, biological, and tissue levels, with the ultimate goal of identifying early predictors of disease development and progression, improving risk stratification, and supporting future strategies for personalized monitoring and intervention.

• Study Type: Observational
• Enrollment (Estimated): 40

Contacts and Locations

• Study Contact: Name: Stefano C Previtali; Phone Number: 0039 0226433036; Email: neuromuscolare@hsr.it
• Study Contact Backup: Name: Benedetta Sorrenti; Phone Number: 0039 0226433036; Email: neuromuscolare@hsr.it

Study Locations

• Italy
  • Milan, Italy, 20132
    • IRCCS Ospedale San Raffaele
    • Contact: Stefano C Previtali; Phone Number: 0039 0226433036; Email: neuromuscolare@hsr.it
    • Contact: Benedetta Sorrenti; Phone Number: 0226433036; Email: neuromuscolare@hsr.it

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Probability Sample

Study Population

The study population consists of adult patients (≥18 years) undergoing evaluation for thymic abnormalities and/or myasthenia gravis at a tertiary referral center. Participants include individuals with thymoma or other thymic pathology, with or without MG-related antibodies and with or without clinically manifest myasthenia gravis, as well as patients with established myasthenia gravis without evidence of thymic abnormalities.

Participants are recruited from routine clinical care settings, including neurology and thoracic surgery units, and reflect a spectrum of clinical and immunological phenotypes relevant to disease development and progression. This population enables the investigation of the relationship between thymic pathology, systemic immune profiles, and neuromuscular junction involvement in myasthenia gravis.

Description

Inclusion Criteria:

• Age ≥18 years at the time of informed consent
• Ability to provide written informed consent and comply with study procedures
• Availability of a serum sample for testing MG-related antibodies
• Availability of chest imaging (CT and/or MRI) to classify thymic status

Participants must also meet the criteria for at least one of the following study groups:

Cohort 1: Thymoma with MG-related antibodies

• Histologically or radiologically confirmed thymoma
• Presence of at least one pathogenic MG-related antibody (AChR)
• Presence or absence of clinically manifest myasthenia gravis

Cohort 2: Other thymic abnormalities with MG-related antibodies

• Imaging or histological evidence of non-thymomatous thymic pathology (e.g., thymic hyperplasia)
• Presence of at least one pathogenic MG-related antibody (AChR)
• Presence or absence of clinically manifest myasthenia gravis

Cohort 3: Thymoma without MG-related antibodies

• Histologically or radiologically confirmed thymoma
• Negative for pathogenic MG-related antibodies (AChR)
• No clinical diagnosis or symptoms suggestive of myasthenia gravis

Cohort 4: Myasthenia gravis without thymic abnormalities

• Established clinical diagnosis of myasthenia gravis with consistent clinical features, supported by at least one of the following:

  1. Seropositivity for MG-related antibodies (AChR, MuSK, or LRP4), or
  2. Abnormal neuromuscular transmission demonstrated by SFEMG or RNS, or
  3. Improvement of MG signs with treatment such as oral acetylcholinesterase inhibitors, plasma exchange, IVIg, or corticosteroids
• Absence of thymic abnormalities on CT or MRI

Exclusion Criteria:

• Inability to provide informed consent
• Other neuromuscular diseases that could interfere with interpretation of clinical or neurophysiological findings
• Severe uncontrolled systemic illness that, in the investigator's judgment, may limit participation or confound study outcomes
• Any medical or psychiatric condition, or history of substance abuse, that may compromise adherence to study procedures
• Pregnancy or breastfeeding

Study Plan

How is the study designed?

Number of groups / cohorts

4

Cohorts and Interventions

Group / Cohort
Patients with thymoma and MG-related antibodies; Patients with histologically or radiologically confirmed thymoma and presence of MG-related antibodies (AChR), with or without clinically manifest myasthenia gravis.
Patients with other thymic abnormalities and MG-related antibodies; Patients with non-thymomatous thymic pathology (e.g., thymic hyperplasia) and presence of MG-related antibodies (AChR), with or without clinically manifest myasthenia gravis.
Thymoma patients without MG-related antibodies; Patients with confirmed thymoma, negative for MG-related antibodies, and without clinical signs or diagnosis of myasthenia gravis.
Patients with established MG without thymic abnormalities; Patients with an established diagnosis of myasthenia gravis based on clinical, serological, and/or neurophysiological criteria, and no evidence of thymic abnormalities.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Qualitative assessment of neuromuscular junction structural abnormalities in intercostal muscle samples	The primary outcome is the qualitative assessment of neuromuscular junction structural abnormalities in residual intercostal muscle samples collected from participants undergoing clinically indicated thymectomy. Neuromuscular junction integrity will be evaluated using histological, immunofluorescence, and ultrastructural analyses, including assessment of acetylcholine receptor clustering, IgG and complement deposition, postsynaptic fold morphology, and features of synaptic remodeling or immune-mediated injury. Structural abnormalities will be described in terms of presence or absence and, where applicable, semi-quantitative grading. Findings will be compared across participant groups according to thymic pathology, MG-related antibody status, and the presence or absence of clinically manifest myasthenia gravis.	At the time of thymectomy (baseline)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Qualitative assessment of thymic histopathological features	Qualitative assessment of thymic histopathological features in thymic tissue collected from participants undergoing clinically indicated thymectomy. Thymic tissue will be evaluated for histopathological features including thymoma subtype, thymic hyperplasia, germinal centers, lymphoid infiltrates, and AIRE expression, where applicable. Histopathological findings will be described in terms of presence or absence and, where applicable, semi-quantitative grading. These features will be analyzed in relation to neuromuscular junction structural abnormalities identified in intercostal muscle samples, as well as according to MG-related antibody status and the presence or absence of clinically manifest myasthenia gravis.	At the time of thymectomy (baseline)
Change in Myasthenia Gravis Activities of Daily Living (MG-ADL) score	The MG-ADL is an 8-item scale assessing myasthenia gravis-related symptoms and functional impairment, with a total score ranging from 0 to 24. Higher scores indicate greater disease burden. Changes from baseline will be evaluated during follow-up and analyzed in relation to biological markers, neuromuscular junction findings, and electronically collected patient-reported symptom scores.	Baseline, 6, 12, and 18 months
Change in Quantitative Myasthenia Gravis (QMG) score	The QMG is a 13-item examiner-administered scale assessing muscle weakness and fatigability, with a total score ranging from 0 to 39. Higher scores indicate greater disease severity. Changes from baseline will be evaluated during follow-up and analyzed in relation to biological markers, neuromuscular junction findings, and electronically collected patient-reported symptom scores.	Baseline, 6, 12, and 18 months
Change in serum MG-related autoantibody levels over time	Measurement of serum levels of MG-related autoantibodies, including acetylcholine receptor (AChR) antibodies, assessed using cell-based assays and ELISA assays. Autoantibody levels will be reported as titers and evaluated at baseline and during follow-up to describe their distribution and longitudinal changes. These measurements will be analyzed in relation to clinical and neurophysiological findings, as well as thymyc histopathology and neuromuscular junction structural features.	Baseline, 6, 12, and 18 months
Change in plasma and serum levels of complement activation products	The secondary outcome is the change in plasma and serum levels of complement activation products, including C3b, C5a, and sC5b-9, assessed using immunoassay-based methods. Changes in complement activation product levels will be evaluated from baseline to follow-up visits and reported as concentrations. These measurements will be analyzed in relation to clinical and neurophysiological findings, as well as thymic histopathology and neuromuscular junction structural features.	Baseline, 6, 12, and 18 months
Change in mean daily composite MG symptom questionnaire score (electronically collected)	The electronic tool consists of a structured daily questionnaire in which patients report symptom severity across four domains (ocular, bulbar, respiratory, and limb involvement), using a visual analogue scale (VAS, 0-10 for each item; 0 = no symptoms, 10 = maximum severity). Individual item scores are summed to generate a daily composite score (range 0-40), with higher scores indicating greater symptom burden. The mean daily composite score will be calculated over predefined time intervals during follow-up, and changes from baseline will be evaluated longitudinally. The questionnaire is based on domains derived from the Myasthenia Gravis Activities of Daily Living (MG-ADL) instrument. Patient-reported scores will be compared with MG-ADL and Quantitative Myasthenia Gravis (QMG) scores assessed at scheduled visits to evaluate concordance and the ability to capture symptom fluctuations over time.	Baseline and up to 18 months

Collaborators and Investigators

• Sponsor: IRCCS San Raffaele
• Investigators: Principal Investigator: Stefano C Previtali, IRCCS Ospedale San Raffaele

Study record dates

Study Major Dates

• Study Start (Estimated): September 15, 2026
• Primary Completion (Estimated): September 14, 2029
• Study Completion (Estimated): December 1, 2029

Study Registration Dates

• First Submitted: April 22, 2026
• First Submitted That Met QC Criteria: April 30, 2026
• First Posted (Actual): May 6, 2026

Study Record Updates

• Last Update Posted (Actual): May 6, 2026
• Last Update Submitted That Met QC Criteria: April 30, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Keywords: myasthenia gravis; thymoma
• Additional Relevant MeSH Terms: Nervous System Diseases; Neoplasms by Site; Neoplasms; Neuromuscular Diseases; Autoimmune Diseases; Immune System Diseases; Neoplasms by Histologic Type; Autoimmune Diseases of the Nervous System; Neurodegenerative Diseases; Thoracic Neoplasms; Lymphatic Diseases; Paraneoplastic Syndromes, Nervous System; Nervous System Neoplasms; Paraneoplastic Syndromes; Neuromuscular Junction Diseases; Neoplasms, Complex and Mixed; Thymus Neoplasms; Hemic and Lymphatic Diseases; Myasthenia Gravis; Thymoma
• Other Study ID Numbers: OSRSCP_TAILOR-MG

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No