The goal of this clinical trial is to learn about how a migraine prevention medicine works for people who have migraines/headaches with their menstrual period. The study includes people ages 18 to 45 who have been diagnosed with migraine and who have a migraine with their menstrual period or those who have migraines with their menstrual period and at other times of the month as well.

The main question the study aims to answer are:

• Does fremanazemab, an injectable calcitonin gene-related peptide (CGRP) pathway targeting therapy, decrease migraines associated with menstruation?

Participants will

• have an evaluation and examination by a headache specialist physician
• will receive the study medicine or inactive substitute every three months for two treatments
• fill out diaries about their migraines
• have tests on saliva to measure hormone levels

Researchers will compare the people who get the medicine to those who get the inactive substitute to see if there are differences in response.

Patients who meet the eligibility criteria and wish to participate will be consented, and will then be randomized to receive two rounds of treatment with either fremanezumab or placebo, administered 3 months apart, to understand efficacy and response in decreasing migraine days. The investigators will monitor with daily logs and use evidenced metrics to assess response. Participants will be carefully screened to ensure that they do not become pregnant while in the study. The investigators will measure monthly hormone levels using salivary samples. Each participant will have three in-person visits and will have five 5 visits via secure telehealth. The investigators are studying decreased headache days, severity, disability and quality of life.

Inclusion Criteria:

Patients may be randomized in this study only if they meet all of the following criteria:

1. The patient is capable of giving signed informed consent, which includes compliance with the requirements and restrictions listed in this protocol

2. The patient is female aged 18 to 45 years of age, inclusive

3. The patient has a diagnosis of pure menstrual migraine (MM) or menstrual-related migraine (MRM)

4. Prior to the screening visit (V1) the patient has a 6 month history of either:

   • Menstrual Migraine (MM)
   • Headache consistent with Menstrual Migraine (MM)
   • Menstrually-Related Migraine (MRM)

5. The patient fulfils the following criteria for migraine in a prospectively collected diary during the 28-day baseline period:

   ○ Migraine attacks starting in the peri-menstrual period (days -2 to +3 of menstruation)

   AND

   • Pure Menstrual migraine with aura, either/or
   • Menstrually-related migraine with aura, either/or
   • Pure Menstrual migraine without aura, either/or
   • Menstrually-related migraine without aura

6. The patient agrees not to initiate any migraine preventive medications during the study

7. The patient is in good health in the opinion of the sponsor as determined by medical evaluation, including medical history, neurologic examination, laboratory tests and cardiac monitoring

8. The patient has a body weight ≥45 kg and a body mass index within the range of 17.5 to 34.9 kg/m^2, inclusive

9. The patient demonstrated compliance with the electronic headache diary during the 28-day baseline period by entry of headache data on a minimum of 21 days cumulative during the 28-day baseline period (~diary compliance)

10. Three months of regular menstrual cycle prior to baseline period and 1 regular cycle (within 21-28 days) of previous cycle during the baseline run-in period

11. Patients not using birth control must have a negative urine beta-human chorionic gonadotrophin(β-HCG) test at the Screening Visit (V1), and must not be in a sexual relationship with a person who produces sperm or must be medically confirmed as sterile. These conditions must be met from the baseline period through the entire duration of study and 5.5 months after the last dose of fremanezumab.

12. Patients using birth control must have a negative β-HCG test result and practice a highly effective method of birth control prior to treatment administration and 5.5 months following the last dose of IMP. Birth control permitted should allow estrogen drop and maintenance of monthly cycle: estrogen/progesterone pills; etonogestrel/ethinylestradiol ring; copper intrauterine device (IUD) and progesterone-containing IUD and have been on their current birth control for ≥30 days.

13. The patient must be willing and able to comply with study restrictions and attend the clinic for all study visits required for the duration of the study and to attend follow up evaluations, as specified in the protocol

Exclusion Criteria:

Patients will not be randomized/enrolled in this study if they meet any of the following criteria:

1. The patient uses medications containing opioids or barbiturates on more than 4 days during the 28-day baseline period for the treatment of migraine or any other reason

2. The patient uses >8 rimegepant or ubrogepant tablets per month

3. The patient has ≥15 headache days per month

4. The patient has used am intervention/device (eg, scheduled nerve blocks, implantable vagal nerve stimulation, and transcranial magnetic stimulation) for migraine during the 2 months prior to screening

5. The patient is overusing acute medication

6. The patient is pregnant or lactating or planning to get pregnant in ≤13 months post screening visit (V1)

7. The patient has clinically significant hematological, cardiac, renal, endocrine, pulmonary, gastrointestinal, genitourinary, neurologic, hepatic or ocular disease, at the discretion of the sponsor

8. The patient has a history of clinically significant cardiovascular disease or vascular ischemia (such as myocardial, neurological [eg, cerebral ischemia], peripheral extremity ischemia, or other ischemic event) or thromboembolic events (arterial or venous thrombotic or embolic events), such as cerebrovascular accident (including transient ischemic attacks), deep vein thrombosis, or pulmonary embolism

9. The patient has a known infection or history of human immunodeficiency virus, tuberculosis, any history of Lyme disease, or chronic hepatitis B or C infection

10. The patient has a past or current history of cancer, except for appropriately treated non-melanoma skin carcinoma

11. The patient has a history of hypersensitivity reactions to injected proteins, including monoclonal antibodies

12. The patient has participated in a clinical study of a new chemical entity or a prescription medicine within 2 months of the screening visit (V1) or 3 months in case of biologics if the half-life of the biologics is unknown or 5 half-lives, whichever is longer, or is currently participating in another study of an IMP (or a medical device)

13. The patient has previously received treatment with any calcitonin generelated peptide pathway (ligand/receptor) target therapy(erenumab, eptinezumab, galcanezumab, fremanezumab, rimegepant 75 mg every other day, or atogepant) or is actively taking them during the study

14. The patient has any finding in the baseline 12-lead electrocardiogram considered clinically significant in the judgment of the sponsor

15. The patient has any finding that, in the judgment of the sponsor, is a clinically significant abnormality, including serum chemistry, hematology, coagulation, and urinalysis test values (abnormal tests may be repeated for confirmation)

16. The patient has a prior medical history of hepatic enzymes (alanine aminotransferase, aspartate aminotransferase, and alkaline phosphatase) >1.5x the upper limit of the normal range or suspected hepatocellular damage that fulfills the criteria for Hy's law during their prior medical history review at screening visit.

17. The patient has a prior medical history of significant proteinuria or evidence of renal disease at the Screening Visit (V1).

18. The patient has any clinically significant uncontrolled medical condition (treated or untreated). The patient has a history of alcohol or drug abuse in the opinion of the sponsor

19. The patient cannot participate or successfully complete the study, in the opinion of their healthcare provider or the sponsor, for any of the following reasons:

    • mentally or legally incapacitated or unable to give consent for any reason
    • in custody due to an administrative or a legal decision, under tutelage, or being admitted to a sanitarium or social institution
    • unable to be contacted in case of emergency
    • has any other condition, which, in the opinion of the sponsor, makes the patient in appropriate for inclusion in the study

20. The patient is an employee who is directly involved in the study or the relative of such an employee

21. The patient has any disorder that may interfere with the absorption, distribution, metabolism, or excretion of IMP

22. The patient is vulnerable (eg, people kept in detention)

23. The patient has previously participated in this study

A research pharmacist who is not on the study team will randomize the study arms.