A Study to Learn About the Safety and Effects of Rimegepant to Prevent Migraine in Chinese Subjects.

A Phase 3, Randomized, Double-Blind, Placebo-Controlled Study to Evaluate the Efficacy and Safety of Rimegepant for Migraine Prevention in Chinese Participants

The purpose of this study is to learn about the effects of Rimegepant to help prevent migraine.

This study is seeking for participants who:

• Are male and female of 18 years of age or older.
• Have at least 1 year history of migraine .
• Did not take any medication for migraine before the start of this study. The study will go on for around 30 weeks, including 4 Phases and 11 Visits. Participants who are selected for the study will be randomly assigned to treatment groups. After which, the participants will enter a 12-week Double-blind Treatment (DBT) Phase. After finishing the DBT Phase, some selected participants may enter a 12-week Open-label Extension (OLE) Phase. Participants will come back to the study site at the end of Week 24 for the End of Treatment (EOT) Visit. There will be a follow-up Week 2 Visit around 14 days after the EOT visit.

Participants will be asked to take 1 tablet of study medicine every other calendar day. This need to be followed regardless of whether they have a migraine on that day or not. During the OLE Phase only, if a participant has a migraine on a non-scheduled dosing day, they may take 1 tablet of Rimegepant orally disintegrating tablet (ODT) as acute treatment for their migraine, if needed, with a maximum of 1 tablet of Rimegepant per calendar day. The study team will look at how each participant is doing with the study treatment during the regular visits at the study clinic.

Inclusion Criteria:

1.Target Population: Participant has at least 1 year history of migraine (with or without aura) consistent with a diagnosis according to the International Classification of Headache Disorders, 3rd Edition, including the following:

1. Age of onset of migraines prior to 50 years of age
2. Migraine attacks, on average, lasting 4 to 72 hours if untreated
3. Per participant report, 4 to18 migraine attacks of moderate or severe intensity per month within the last 3 months prior to the Screening Visit (month is defined as 4 weeks for the purpose of this protocol)
4. 6 or more migraine days during Observation Phase
5. Not more than 18 headache days during the Observation Phase
6. Ability to distinguish migraine attacks from tension/cluster headaches.
7. Participants with contraindications for use of triptans may be included provided they meet all other study entry criteria.

Exclusion Criteria:

1. Participant has a history of basilar migraine or hemiplegic migraine.
2. Participants are excluded if they have had no therapeutic response with > 2 of the 9 medication categories of preventive treatment of migraine after an adequate therapeutic trial in the past 3 years per investigator's judgement.