This is a randomised, placebo controlled, double blind, crossover proof of concept study to investigate the efficacy and safety of oral LAT8881 in acute migraine, with or without aura.

Subjects enrolled in the study will be randomised to receive investigational medicinal product (LAT8881 60 mg or placebo), to be taken at the onset (within one hour from the onset of pain) of a migraine headache of moderate to severe intensity [Numeric rating scale greater than 4]. Rescue medication should not be taken until at least 2 hours post dose. Subjects will be given a single dose of either active or placebo, to treat one migraine headache.

After treatment of one migraine headache (or a maximum 28 days) the subject will return to the clinic for re-evaluation and crossover to the second treatment. After treatment of one migraine headache in the second treatment period or a maximum of 28 days from commencement of the second treatment period, the subject will return to the clinic for re-evaluation. An End of study visit (telephone) will occur 7 days after the end of the second treatment period.

Inclusion Criteria:

1. Males or females aged 18 to 75 years at the time of consent
2. Diagnosis of episodic migraine headache at least 12 months ago with or without aura as defined in International Classification of Headache-3
3. Onset of migraine headache before age 50
4. Medical history of 2 - 8 migraine headache attacks per month for the previous 12 months; ≥ 75% of attacks progress to moderate or severe pain within 2 hours (ie, rapidly-escalating)
5. Minimum 48 hours on average between migraine headache attacks
6. Acute headache medication on ≤ 14 days/month in the 3 months prior to screening
7. Willing and able to comply with all study procedures including completion of a headache diary and a migraine diary on the day of a migraine headache

Exclusion Criteria:

1. Unable to distinguish migraine from other primary headache conditions

2. Average of 15 or more headache (migraine or nonmigraine) days per month or history of more than 25% of headaches occurring at time of wakening (wake up headaches)

3. History of aura lasting more than 60 minutes

4. History of vomiting within 2 hours of onset of a migraine headache in more than 25% of migraine headaches

5. Medication overuse headache, defined as:

   1. use of opioids, triptans or ergot alkaloids or any combination of these medications for treatment of headaches 10 or more days per month during the 90 days prior to screening OR
   2. Non-steroidal anti-inflammatory drugs (NSAIDs) or simple analgesics for treatment of headaches on more than 14 days per month during the 90 days prior to screening

6. Recent (3 years) history of frequent or chronic hemiplegic/ basilar migraine, tension headache, retinal migraine, ophthalmoplegic migraine as per ICHD classification, or treatment resistant atypical migraine

7. Hospital admission for status intractable migraine or medication overuse headache within 6 months of screening

Adverse event data was collected from the first dose until the end of study visit, approximately 64 days