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OpenTrials
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NCT Number: NCT05451212

Open-label Study to Evaluate the Safety of Various Dosing Regimens of MuSK-CAART for MuSK Myasthenia Gravis

Muscle-specific tyrosine kinase (MuSK) myasthenia gravis (MG) is a rare but potentially severe disease, in which patients develop pathogenic autoantibodies that specifically target the MuSK protein in the neuromuscular junction. This phase 1 study is being conducted to evaluate the safety of various dosing regimens of an investigational cell therapy, MuSK-CAART, that can be given to patients with anti-MuSK antibody positive Myasthenia Gravis (MuSK MG), who have active disease. Various dosing regimens of MuSK-CAART alone, in combination with cyclophosphamide (CY), and in combination with CY and fludarabine (FLU) will be evaluated. Treatment with MuSK-CAART may potentially lead to complete and durable remission of disease.

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Key information

Conditions

MuSK Myasthenia Gravis Autoimmune Diseases Autoimmune Diseases of the Nervous System Immune System Diseases Muscle Weakness Muscular Diseases Musculoskeletal Diseases Myasthenia Gravis Neoplasms Neoplasms by Site Nervous System Diseases Nervous System Neoplasms Neurodegenerative Diseases Neurologic Manifestations Neuromuscular Diseases Neuromuscular Junction Diseases Neuromuscular Manifestations Paraneoplastic Syndromes Paraneoplastic Syndromes, Nervous System Pathologic Processes Pathological Conditions, Signs and Symptoms Signs and Symptoms

Age range

18 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 1

Primary location

UC Irvine, Department of Neurology, Orange, California, United States

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Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Confirmed diagnosis of MuSK-type MG with at least 1 prior positive anti-MuSK antibody test.
  • History of a negative anti-AChR (acetylcholine receptor) antibody test.
  • Positive anti-MuSK antibody test at screening
  • MG severity Class I to IVa on the MGFA (Myasthenia Gravis Foundation of America) Clinical Classification

Exclusion criteria

  • Rituximab in the last 12 months.
  • Prednisone > 0.25mg/kg/day [in Part A]
  • Other autoimmune disorder requiring immunosuppressive therapies.
  • Investigational treatment for MG in the past 12 weeks.
  • Absolute lymphocyte count < 500/µL at screening.

Treatment and study plan

MuSK-CAART

Biological

Intravenous infusion of MuSK-CAART at different doses. Subjects may also receive MuSK-CAART following pre-treatment with CY, or CY plus FLU.

Primary outcomes

  1. Adverse events

    Time frame: 3 months

    Incidence of adverse events (AEs), including dose-limiting toxicities (DLTs) and AEs that are related to MuSK-CAART.

Secondary outcomes

  1. Total MuSK-CAART positive cells

    Time frame: Baseline

    Total MuSK-CAART positive cells for each manufacturing run.

  2. Percent of CAAR-transduced cells

    Time frame: Baseline

    Percent of total cells for infusion that are CAAR (Chimeric Autoantibody Receptor)-transduced cells.

  3. Cellular kinetics profile of MuSK-CAART

    Time frame: Up to 36 months

    Cellular kinetics profile of MuSK-CAART after infusion.

  4. Change in MuSK autoantibody titer

    Time frame: Up to 36 months

    Change in MuSK autoantibody titer compared to pre-infusion visit by clinically validated assay.

Other outcomes

  1. Use of Concomitant Therapies

    Time frame: Up to 36 months

    Frequency and dose of concomitant therapies.

  2. Measurement of Clinical Symptoms using MG-ADL

    Time frame: Up to 36 months

    Measurement of clinical symptoms using the Myasthenia Gravis Activities of Daily Living (MG-ADL) assessment.

  3. Measurement of Clinical Symptoms using QMG

    Time frame: Up to 36 months

    Measurement of clinical symptoms using the Quantitative Myasthenia Gravis (QMG) assessment.

  4. Measurement of Clinical Symptoms using MGC

    Time frame: Up to 36 months

    Measurement of clinical symptoms using the Myasthenia Gravis Composite (MGC) assessment.

  5. Measurement of Quality of Life (QoL) using MG-QOL-15r

    Time frame: Up to 36 months

    Measurement of Quality of Life using the MG-QOL-15r (Myasthenia Gravis Qualify of Life 15-item scale, revised) questionnaire.

Sponsors and collaborators

Lead sponsor

Cabaletta Bio

Industry

Registry information

Official study title

A Phase 1, Open-label, Safety and Dose-finding Study of Autologous Muscle-specific Tyrosine Kinase Chimeric Autoantibody Receptor T Cells (MuSK-CAART) in Subjects With Anti-MuSK-antibody-positive Myasthenia Gravis

Important dates

Study start
2022
Primary completion
2025
Study completion
2025
First posted
Jul 11, 2022
Registry last updated
Nov 10, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

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This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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