Talquetamab in Patients With Refractory Generalized Myasthenia Gravis

A Preliminary Case Study to Evaluate the Efficacy and Safety of Talquetamab in Patients With Refractory Generalized Myasthenia Gravis

Myasthenia Gravis (MG) is a chronic autoimmune disease mediated by pathogenic antibodies. Approximately 10%-15% of patients present with refractory status, defined as having an inadequate response to existing therapies or an inability to tolerate the side effects of the medication, highlighting an urgent need for the development of more targeted innovative therapies. Talquetamab is a bispecific antibody that targets G Protein-Coupled Receptor Class C Group 5 Member D (GPRC5D) and the Cluster of Differentiation 3 (CD3) molecule on the surface of T cells, thereby inducing T cells to precisely eliminate GPRC5D-positive cells. This study will conduct an exploratory case series to investigate the efficacy and safety of Talquetamab in refractory MG.

Study Overview

• Status: Not yet recruiting
• Conditions: Myasthenia Gravis (MG)
• Intervention / Treatment: Drug: Talquetamab

• Study Type: Interventional
• Enrollment (Estimated): 2
• Phase: Not Applicable

Participation Criteria

Eligibility Criteria

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

Description

Inclusion Criteria:

• The patient must sign the informed consent form for participation in the study and agree to comply with the study procedures.
• Age 18-70 years.
• Must meet the clinical diagnostic criteria for MG, defined as presenting with a typical pattern of weakness (predominantly affecting proximal muscles, fatiguability, fluctuating severity, worse with prolonged effort and better after rest) and meeting any one of the following three conditions: documented history of abnormal neuromuscular transmission confirmed by single-fiber electromyography or repetitive nerve stimulation; documented history of a positive neostigmine test; or improvement in MG signs following oral administration of an acetylcholinesterase inhibitor. Additionally, the Myasthenia Gravis Foundation of America (MGFA) clinical classification must be II-IV, and the patient must be positive for anti-AChR antibodies.
• Must meet the definition of "refractory myasthenia gravis" according to the Chinese Guidelines for the Diagnosis and Treatment of Myasthenia Gravis (2025 Edition): defined as having a suboptimal response to conventional immunotherapeutic drugs, intolerance to or having contraindications for adverse drug reactions, or experiencing frequent disease relapses requiring regular rescue therapy, making it difficult to achieve treatment goals.
• Myasthenia Gravis Activities of Daily Living (MG-ADL, Appendix 1) score ≥6, with >50% of the score derived from non-ocular items.
• Quantitative Myasthenia Gravis (QMG) score (Appendix 2) ≥8, with >50% of the score derived from non-ocular items.
• The dosage of pyridostigmine bromide must be stable for at least 1 week prior to the treatment period.

Exclusion Criteria:

• Patients who have had their glucocorticoid dose adjusted, or who have received immunoglobulins, plasma exchange, neonatal Fc receptor inhibitors, or complement inhibitors within ≤4 weeks.
• Patients who have undergone thymectomy, received B-cell depletion therapy, or had their dose of non-steroidal immunosuppressants (such as azathioprine, tacrolimus, mycophenolate mofetil, cyclophosphamide, etc.) adjusted within ≤3 months.
• Patients who have participated in any interventional clinical trial or received investigational treatment within ≤3 months, or within 5 half-lives of the received investigational drug (whichever is longer).
• Patients with concurrent severe liver, kidney, cardiac, pulmonary, or coagulation dysfunction.
• Patients with concurrent chronic infections such as Human Immunodeficiency Virus, Hepatitis B Virus, Hepatitis C Virus, or Mycobacterium tuberculosis.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: treatment group; Talquetamab	Drug: Talquetamab; Eligible patients will receive the drug via subcutaneous injection on Days 1, 3, and 5, respectively. The dose will be determined based on body weight measured before administration, according to the following table. A total of 3 doses will be administered. Administration Day and Dose: 0.01 mg/kg in Day 1; 0.06 mg/kg in Day 3; 0.4 mg/kg in Day 5.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
MG-ADL score	Full scale title: Myasthenia Gravis Activities of Daily Living Profile (MG-ADL) Score range: 0-24 A higher score means worse outcomes (greater symptom severity and more impairment in daily functioning).	baseline, and 1-6 months

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
QMG score	Full scale title: Quantitative Myasthenia Gravis Score (QMG), also referred to as the Quantitative Myasthenia Gravis Scale . Score range:0-39 A higher score means worse outcomes (more severe disease and greater weakness). Conversely, a lower score indicates milder disease or better symptom control .	baseline and 1-6 months

Collaborators and Investigators

• Sponsor: First Affiliated Hospital of Chongqing Medical University

Study record dates

Study Major Dates

• Study Start (Estimated): March 20, 2026
• Primary Completion (Estimated): March 20, 2027
• Study Completion (Estimated): April 1, 2027

Study Registration Dates

• First Submitted: March 24, 2026
• First Submitted That Met QC Criteria: March 24, 2026
• First Posted (Actual): March 30, 2026

Study Record Updates

• Last Update Posted (Actual): April 8, 2026
• Last Update Submitted That Met QC Criteria: April 3, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Nervous System Diseases; Neoplasms by Site; Neoplasms; Neuromuscular Diseases; Autoimmune Diseases; Immune System Diseases; Autoimmune Diseases of the Nervous System; Neurodegenerative Diseases; Paraneoplastic Syndromes, Nervous System; Nervous System Neoplasms; Paraneoplastic Syndromes; Neuromuscular Junction Diseases; Myasthenia Gravis; talquetamab
• Other Study ID Numbers: KX2026-KYC102-01

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: With the consent of the project leader and research subjects, after the research is completed (expected to start in May 2026), it can be done via email feixiao81@126.com Contact the project leader to obtain desensitization data.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: Yes