Efficacy and Safety of HN2301 in Refractory Myasthenia Gravis(MG)

Inclusion Criteria

* Age: 18-80 years, no gender restriction;
* Confirmed diagnosis of generalized myasthenia gravis (MG) with positive AchR or MuSK antibodies, meeting at least one of the following conditions:

  (1) Repetitive nerve stimulation suggesting neuromuscular transmission defect; (2) Positive response to neostigmine test; (3) Clinically judged improvement of --MG symptoms after oral cholinesterase inhibitor therapy;
* Clinical classification of MG according to MGFA types IIa-IVb (including IIa, IIb, IIIa, IIIb, IVa, IVb);
* Baseline MG-ADL (Myasthenia Gravis Activities of Daily Living) score ≥6, with ocular-related score \<50%;
* Poor response and/or lack of effective treatment under standard therapies, defined as no improvement or worsening of symptoms despite stable treatment with corticosteroids, immunosuppressants (e.g., azathioprine, mycophenolate mofetil, tacrolimus, cyclosporin A, cyclophosphamide), or rituximab;
* Expected survival time greater than 12 weeks;
* Adequate bone marrow, coagulation, cardiopulmonary, liver, and renal function；Bone marrow function: ANC ≥1.5×10⁹/L, ALC ≥0.8×10⁹/L, Hb ≥80g/L; transfusions or growth factors must not be used within 7 days prior to screening to meet these criteria.Coagulation function: INR or APTT ≤1.5×ULN.
* Cardiac function: left ventricular ejection fraction (LVEF) ≥40% assessed by echocardiogram (ECHO).
* Pulmonary function: CTCAE grade ≤1 dyspnea and room air SpO₂ ≥92% (measured by pulse oximetry).
* Liver function: ALT and AST ≤2.5×ULN; total bilirubin \<2.0 mg/dL (or \<3.0 mg/dL for subjects with Gilbert's syndrome).
* Renal function: calculated creatinine clearance (Cockcroft-Gault) ≥50 mL/min without hydration assistance.

Exclusion Criteria

* Subjects positive for hepatitis B surface antigen (HBsAg) and/or hepatitis B core antibody (HBcAb) with detectable or quantifiable HBV DNA, positive for hepatitis C antibody (HCV Ab) with detectable or quantifiable HCV RNA, positive for HIV antibody, positive CMV DNA, or CMV DNA above the upper limit of detection; positive for syphilis antigen or antibody;
* Presence of other uncontrolled active infections;
* History of major organ transplantation (e.g., heart, lung, liver, kidney) or bone marrow/hematopoietic stem cell transplantation;
* Pregnant or breastfeeding women;
* Receipt of any mRNA-LNP products or other LNP-based drugs within the past two years;
* History of any of the following cardiovascular conditions within 6 months prior to screening: New York Heart Association (NYHA) Class III or IV heart failure, myocardial infarction, unstable angina, uncontrolled or symptomatic atrial arrhythmias, any ventricular arrhythmias, or other clinically significant cardiac disease;
* History of ≥Grade 2 bleeding events within 30 days prior to screening, or requiring long-term continuous anticoagulation therapy (e.g., warfarin, low molecular weight heparin, Xa factor inhibitors);
* History of live vaccination within 30 days prior to screening;
* Severe central nervous system diseases or pathological changes, including but not limited to: cerebrovascular accident, aneurysm, epilepsy, seizures/convulsions, aphasia, stroke, severe brain injury, dementia, Parkinson's disease, cerebellar disorders, organic brain syndromes, or psychosis;
* History of asthma or severe allergies;
* Any condition that, in the investigator's opinion, may increase the patient's risk or interfere with study assessments.