Does Myasthenia Gravis Affect Your Daily Routine?If you have been diagnosed with MuSK-positive myasthenia gravis (MuSK-MG) or have received a positive anti-AChR antibody test, your participation in this clinical trial may help other sufferers.

INSIDE: Learn how you can be part of the THE MuSK Trial

THE MuSK Trial enrollment has begun

Help Change How MuSK-MG Is Treated Talk with your treating physician about participating in THE MuSK Trial

What is THE MuSK Trial?

THE MuSK Trial will evaluate the effectiveness of amifampridine phosphate in controlling, reducing, and/or eliminating the symptoms of MuSK-MG.

This study is needed for FDA approval. By participating in this study you will help:

• Increase our understanding of amifampridine phosphate in the treatment of MuSK-MG

• Provide important clinical data needed for FDA approval

• Develop a new treatment option for MuSK-MG

Who can participate in the study?Only adult patients with a positive anti-MuSK antibody test or a positive anti-AChR antibody test may enroll in the trial.

Where is the study being conducted?The study will be conducted at multiple locations across the United States and a limited number of sites in Italy. Talk with your doctor about finding a center near you, or contact us at:

E-mail: MuSKMG@catalystpharma.com

Phone: 1.844.347.3277

All study-related testing and evaluations will be conducted at the respective university or clinical research centers.

What can I expect during the study?After an initial screening period (up to 14 days), the study will take approximately 38 days. Women participating in the study cannot be pregnant and must use contraceptives throughout the study and then for 30 days after completion.

The study will be examining the most effective and tolerable dose of amifampridine phosphate so, at some point during the study, you may receive a higher dose of the study medication. Close monitoring and 24-hour medical oversight will ensure safety.

With your help, we may change the course of MuSK-MG treatment

AChR=acetylcholine receptor; EMG=electromyogram.

Will I have access to the medication after the study?

After the study, eligible participants can choose to enter an open-label extension study and will continue to receive the study medication.

What happens in the clinical evaluation?

The evaluation includes:

• Strength tests

• Questions about how you are feeling

• Urine samples

• MuSK and/or AChR antibody testing (if not previously done and/or the report is not available)

• Vital signs

• Medical history

• An EMG (if not previously done and/or the report is not available)

Do I need to sign an Informed Consent Document in order to participate?

Yes. This document is necessary for participation in all clinical trials. You’ll receive it from the study physician and have time to review it and ask questions. Your physician will also help answer any questions you may have.

Do I have to pay for anything?

The study sponsor will cover the costs of the study medication and all study-related activities. Other study costs covered by the sponsor include:

• Examinations and tests

• Travel and accommodations

Can I bring my spouse, a friend, or a support person?

Yes. You may bring a support person to help assist you during the study. Their travel, accommodations, and associated expenses may be covered by the sponsor.

Your participation may help to improve the lives of others with MuSK-MG

Summary of THE MuSK Trial

Medical condition under investigation: MuSK antibody-positive myasthenia gravis and the purpose of the study is to determine the degree of MuSK-MG symptom control with amifampridine phosphate treatment.

Eligibility criteria: Adult patients with a positive anti-MuSK antibody test or a positive anti-AChR antibody test.

Participant benefits: All treatment, screening, and participation costs will be covered (examinations and tests, travel accommodations, meals, incidentals); access to expert medical care for the duration of the study; access to continued treatment for eligible patients at the conclusion of the trial through the open- label extension study.

Patient time commitment: THE MuSK Trial will be continuous for at least 38 days; the initial screening may take up to an additional 14 days.

Open-label extension study: Clinic visits for safety assessment and for evaluation of MG-ADL will be made at Months 3, 6, 9, 12, 15, and 21. Additional visits may occur at the discretion of the Investigator.

Study locations: Multiple sites across the United States and a limited number of sites in Italy.

Amifampridine phosphate is an investigational drug and not currently commercially available.This study is being sponsored by Catalyst Pharmaceuticals.@2018 Catalyst Pharmaceuticals, Inc. CAT-MG-PB January 2018

CONTACT US: E-mail: MuSKMG@catalystpharma.com Phone: 1.844.347.3277

OUR WEBSITES:www.themusktrial.comwww.catalystpharma.com

To learn more about the clinical trial go to: www.clinicaltrials.gov/ct2/show/NCT03304054