The goal of this clinical trial is to evaluate the efficacy and safety of Blinatumomab in the treatment of refractory myasthenia gravis, with the expectation of offering a new therapeutic option for refractory patients. The main questions it aims to answer are:

• Does Blinatumomab improve patients' clinical symptoms?
• Is Blinatumomab safe for the treatment of myasthenia gravis?

Participants will:

• Receive two cycles of intravenous Blinatumomab infusion, each lasting 5 days, with a 1-week interval between cycles.
• Visit the clinic once every 4 weeks for checkups and tests.
• Keep a diary of their symptoms and the types and dosages of medications.

Inclusion Criteria:

• Age at onset > 18 years old
• The diagnosis of MG was based on the presence of typical myasthenic symptoms and supported by positive autoantibodies, electrophysiological studies, and/or the neostigmine test.
• Positive or negative for anti-AChR, and/or anti-MuSK, and/or anti-LRP4 antibodies.
• Refractory myasthenia gravis (MG) patients are defined as those who meet any of the following criteria: For patients with ocular MG, the condition is defined as having no significant improvement in disease symptoms (QMG score improvement <25%) after adequate dosing and duration of existing immunosuppressive drugs and targeted biologics, with no change or worsening in the post-intervention status (PIS), or if the PIS improves but disease symptoms worsen or relapse during the regular tapering of immunosuppressive treatment, severely affecting daily quality of life. For generalized MG, the patient must meet the following conditions: no improvement or worsening in PIS after adequate dosing and duration of existing immunosuppressive drugs and targeted biologics; improvement in PIS, but with an MG-ADL score ≥6 persisting for at least six months; remission or improvement in PIS, but with ≥2 episodes of disease exacerbation (MG-ADL ≥6) per year during tapering of immunotherapy medications; patients who, after experiencing a myasthenic crisis, undergo multiple immunotherapies including intravenous efgartigimod, eculizumab, immunoglobulin, plasma exchange, and high-dose intravenous methylprednisolone, and active infection control, but still cannot be weaned off the ventilator due to respiratory muscle weakness from MG for more than 14 days. (Note: This includes patients who cannot tolerate existing treatment drugs due to contraindications, comorbidities, or adverse drug reactions.)
• Receiving stable doses of medication prior to enrollment
• Written informed consent

Exclusion Criteria:

• Patients who have thymoma or have undergone thymectomy within six months
• Patients who have used other biologics prior to enrollment that may affect the efficacy assessment of blinatumomab.
• Severe cardiovascular, hepatic, renal, respiratory, or endocrine diseases, malignancies, or uncontrolled acute or chronic infections
• Pregnancy or lactation, unwillingness to avoid pregnancy
• Patients with other diseases that may affect the assessment of muscle strength
• Other conditions that would preclude participation