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NCT06463587Recruiting

Efficacy and Safety of a New Formulation of Oral Cladribine Compared With Placebo in Participants With Generalized Myasthenia Gravis (MyClad)

Official recordSimplified version

Summary

The purpose of this clinical study is to determine the efficacy and safety of a new oral cladribine formulation in participants with Generalized Myasthenia Gravis (gMG) in comparison to placebo. It will also investigate the sustained efficacy, the need for retreatment, and the long-term safety of oral cladribine in gMG. An additional component is included to characterize the Pharmacokinetics (PK) of the new cladribine formulation in gMG participants. This study is divided into 3 periods: the double-blind placebo control (DBPC) pivotal period, and 2 extensions, the blinded extension (BE) and the retreatment (RT) period. Furthermore, in trial interviews will be conducted as a sub-study to MyClad with a sub-set of participants to gain an in depth understanding of the participant cladribine treatment and study experience.

Inclusion criteria

• Adults of ≥ 18 years of age at the time of signing the informed consent. • Diagnosis of Myasthenia Gravis with generalized muscle weakness, meeting clinical criteria for Myasthenia Gravis Foundation of America Class II to IVa classification. • In participants positive for Acetylcholine receptor antibody (anti-AChR) or muscle-specific kinase antibody(anti-MuSK) • In participants that are autoantibody seronegative i.e. not positive for anti-AChR and anti-MuSK antibodies and participants who are positive for anti-low-density lipoprotein receptor-related protein 4 antibodies (anti-LRP4) • Has a Screening and Baseline MG-ADL score more than or equal to (\>=) 6 with \>= 50 percentage (%) of the total score due to non-ocular symptoms. Screening and Baseline MG-ADL scores must be stable. The difference between the Screening and Baseline scores should not be more than 2 and there should be no reported MG exacerbation during the Screening period • If treated with oral corticosteroids: should be on a stable daily dose for at least 3 months prior to and during screening. In such case, the daily dose of oral steroids should not exceed 20 milligrams(mg)/day for prednisone/ prednisolone, 16 mg/day for methylprednisolone, 3 mg/day for dexamethasone, or 80 mg for hydrocortisone or equivalent doses for other corticosteroids. • If treated with acetylcholinesterase inhibitor should be on a stable daily dose (pyridostigmine dose ≤ 480 mg/day or neostigmine ≤ 300 mg/day) for at least 3 months prior to and during screening • Have a body weight \>= 40 kilograms • Other protocol defined inclusion criteria could apply

Exclusion criteria

• Immunologic disorder other than MG or any other condition requiring chronic oral, intravenous, intramuscular, or intraarticular corticosteroid therapy. Well-controlled thyroid disease, as per the Treating Investigator or the participants regular treating physician recorded in the source documents, is not exclusionary • Molecularly characterized or suspected congenital myasthenic syndrome, Lambert-Eaton myasthenic syndrome, inherited myopathy, muscular dystrophy, acquired myopathy or any other neurologic or systematic disease that mimics MG muscular weakness • Active, clinically significant viral, bacterial, or fungal infection, including brain MRI or chest X-ray findings consistent with signs of infection such as PML or TB, or any major episode of infection requiring hospitalization or treatment with parenteral anti-infectives within 8 weeks prior or during Screening, or completion of oral anti-infectives within 8 weeks prior or during Screening. Vaginal candidiasis, onychomycosis, and genital or oral herpes simplex virus considered by the Investigator to be sufficiently controlled would not be exclusionary • Has a history of or current diagnosis of active tuberculosis (TB) or is currently undergoing treatment for latent TB infection or has an untreated latent TB infection as determined by documented results within 3 months of the Screening Visit of a positive TB skin test . • Active malignancy, or history of cancer or signs of malignancy in any Screening assessment • Treatment with nonsteroidal immunosuppressants, used in gMG, such as azathioprine, mycophenolate mofetil, methotrexate, cyclosporine, cyclophosphamide, tacrolimus within 4 weeks prior to randomization • Treatment with FcRn or complement inhibitors (such as eculizumab, rozanolixizumab efgartigimod, ravulizumab, zilucoplan or nipocalimab) within 8 weeks prior to randomization • History of thymectomy within 6 months prior to Screening. • History of generalized seizures (except for history of febrile seizures during the participant's childhood). • Negative or indeterminate for Varicella Zoster Virus antibodies at screening • History of myasthenic crisis in the last 12 months prior to and during screening • History of recurrent infections (that is 3 or more infections per year documented in available source data) within the last 2 years • Discontinuation of treatment with any non-steroidal immunosuppressants used in gMG, such as azathioprine, mycophenolate mofetil, methotrexate, cyclosporine, cyclophosphamide, tacrolimus within the last 6 months prior to Screening • If treated with non-steroidal immunosuppressants for gMG, the dose at Screening higher than 50 mg/day for azathioprine, 500 mg/day for mycophenolate mofetil, 1 mg/day for tacrolimus, 50 mg/day for cyclosporine, 25 mg/day for cyclophosphamide, or 7.5 mg/week for methotrexate • Participation in clinical study of any investigational drug within 6 months, or 5 half-lives of the investigational drug used in the previous clinical study prior to randomization, whichever is longer. However, participants with any prior exposure to cladribine may not enter the study regardless of timing of exposure • Other protocol defined exclusion criteria could apply

Contacts

The trial team's contact details are shown on request.

See the official trial record
Status
Recruiting
Phase
Phase 3
Study type
Interventional
Countries
Switzerland, France, Germany, Italy, United States, Argentina, Australia, Belgium, Bulgaria, Canada, China, Georgia, Greece, Hungary, India, Japan, Poland, Romania, Serbia, South Korea, Spain, Sweden, Taiwan, Turkey (Türkiye), United Kingdom
Sponsor
Merck Healthcare KGaA, Darmstadt, Germany, an affiliate of Merck KGaA, Darmstadt, Germany(Industry)
Protocol no.
MS700568_0183
Conditions
Generalized Myasthenia Gravis
Interventions
Other, Drug

Treatments studied

  • Placebo
  • Cladribine Low Dose
  • Cladribine High Dose

Collaborators

EMD Serono Research & Development Institute, Inc.

Locations · 150

  • Bern, SwitzerlandInselspital - Universitaetsspital Bern - Neuropsychologische Rehabilitation, NeurologieRecruiting at this site
  • Nice, FranceCHU Nice - Hôpital Pasteur - CardiologyRecruiting at this site
  • Strasbourg, FranceCHU Strasbourg - Hopital Hautepierre - Service Anesthesie-Reanimation&Medecine Peri-OperaRecruiting at this site
  • La Tronche, FranceCHU de Grenoble - Hôpital Albert Michallon - Centre de Références des Maladies NeuromusculairesRecruiting at this site
  • Paris, FranceFondation Ophtalmologique Adolphe de Rothschild - Service de neurologieRecruiting at this site
  • Clermont-Ferrand, FranceCHU Clermont Ferrand - Hopital Gabriel Montpied - service de neurologie BRecruiting at this site
  • Bron, FranceHopital Neurologique Pierre Wertheimer - Pathologies neuro-musculaires. ElectromyographieRecruiting at this site
  • Créteil, FranceHôpital Henri Mondor - Service de NeurologieRecruiting at this site
  • Paris, FranceGroupe Hospitalier Pitie-Salpetriere - Centre Référent Maladies Rares SLA - NeurologieRecruiting at this site
  • Ulm, GermanyUniversitaetsklinikum Ulm - Klinik fuer NeurologieRecruiting at this site
  • Göttingen, GermanyUniversitaetsmedizin Goettingen - Abteilung fuer Nephrologie und RheumatologieRecruiting at this site
  • Hanover, GermanyMedizinische Hochschule Hannover - Klinik fur Neurologie mit Klinischer NeurophysiolRecruiting at this site
  • Bochum, GermanySt. Joseph Hospital - St. Joseph Hospital HaanRecruiting at this site
  • Düsseldorf, GermanyUniversitaetsklinikum Duesseldorf AoeR - Klinik fuer NeurologieRecruiting at this site
  • Dresden, GermanyUniversitaetsklinikum Carl Gustav Carus TU Dresden - Medizinische Klinik IRecruiting at this site
  • Leipzig, GermanyUniversitaetsklinikum Leipzig AoeR - Klinik und Poliklinik fuer NeurologieRecruiting at this site
  • Lübeck, GermanyUniversitaetsklinikum Schleswig-Holstein - Campus Luebeck - NeurologieRecruiting at this site
  • Berlin, GermanyCharité Universitaetsmedizin Berlin - Campus Charité Mitte - Klinik fuer NeurologieRecruiting at this site
  • Bergamo, ItalyAzienda Socio Sanitaria Territoriale Papa GiovanniRecruiting at this site
  • Bologna, ItalyIRCCS Istituto delle Scienze Neurologiche di Bologna - Unità Operativa Complessa Clinica NeurologicaRecruiting at this site
  • Genova, ItalyIRCCS Ospedale Policlinico San Martino - NeuroradiologiaRecruiting at this site
  • Milan, ItalyFondazione IRCCS Istituto Neurologico Carlo BestaRecruiting at this site
  • Pavia, ItalyFondazione Istituto Neurologico Casimiro Mondino - NeurologyRecruiting at this site
  • Rome, ItalyAzienda Ospedaliera Universitaria Policlinico Tor Vergata - U.O.C. NeurologiaRecruiting at this site
  • Rome, ItalyPoliclinico Universitario Agostino Gemelli - UOC NeurologiaRecruiting at this site
  • Treviso, ItalyOspedale ca' Foncello - NeurologyRecruiting at this site
  • Phoenix, United StatesArizona Neuroscience Research, LLCRecruiting at this site
  • Farmington, United StatesUniversity of Connecticut Health Center - Department of MedicineRecruiting at this site
  • Washington D.C., United StatesThe George Washington University Medical Faculty Associates Foggy Bottom South PavilionRecruiting at this site
  • Altamonte Springs, United StatesNeurology of Central Florida Research Center, LLCRecruiting at this site

In total, worldwide, 150 of the 154 sites listed in the registry are recruiting; the other 4 are not currently recruiting.

Site status per the ClinicalTrials.gov registry (last update posted: October 21, 2026).

This status may have changed and says nothing about your eligibility: before taking any step, check with your oncologist or the site.

+ 120 more locations

Other identifiers

  • 2023-507746-83-00 · other registry
  • CTR20243857 · other registry
  • jRCT2031240175 · other registry
  • SNCTP000006603 · other identifier
  • 2023 · NIH grant

See also

Other versions

These results are indicative and do not replace medical advice — discuss them with your doctor.