A headache day was defined as a day when a participant reported a headache of at least moderate severity. Monthly averages were derived and normalized to 28 days equivalent by the following formula: (number of days of efficacy variable over relevant period/number of days with assessments recorded in the e-diary over the relevant period) * 28. The change was calculated as post-baseline value - baseline value. Least square (LS) mean was calculated using analysis of covariance (ANCOVA) model with the duration of post traumatic headache history (less than 12 month since the brain injury or greater or equal to 12 month since the brain injury) and treatment as fixed effects and the baseline monthly average number of headache days of at least moderate severity as a covariate.

Full analysis set (FAS) included all randomized participants who received at least 1 dose of the study drug and had at least 1 post-baseline efficacy assessment on the primary endpoint.

Monthly averages were derived and normalized to 28 days equivalent by the following formula: (number of days of efficacy variable over relevant period/number of days with assessments recorded in the e-diary over the relevant period) * 28.

FAS included all randomized participants who received at least 1 dose of the study drug and had at least 1 post-baseline efficacy assessment on the primary endpoint.

A headache day was defined as a day when a participant reported a headache of at least moderate severity. Monthly averages were derived and normalized to 28 days equivalent by the following formula: (number of days of efficacy variable over relevant period/number of days with assessments recorded in the e-diary over the relevant period) * 28.

FAS included all randomized participants who received at least 1 dose of the study drug and had at least 1 post-baseline efficacy assessment on the primary endpoint.

A headache day was defined as a day when a participant reported a headache of at least moderate severity. Monthly averages were derived and normalized to 28 days equivalent by the following formula: (number of days of efficacy variable over relevant period/number of days with assessments recorded in the e-diary over the relevant period) * 28.

FAS included all randomized participants who received at least 1 dose of the study drug and had at least 1 post-baseline efficacy assessment on the primary endpoint. Here, 'Number analyzed' signifies participants evaluable for this outcome measure at specified timepoints.

A headache day was defined as a day when a participant reported a headache of at least moderate severity. Monthly averages were derived and normalized to 28 days equivalent by the following formula: (number of days of efficacy variable over relevant period/number of days with assessments recorded in the e-diary over the relevant period) * 28. The change was calculated as post-baseline value - baseline value. LS mean was calculated using ANCOVA model with the duration of post traumatic headache history (less than 12 month since the brain injury or greater or equal to 12 month since the brain injury) and treatment as fixed effects and the baseline monthly average number of headache days of at least moderate severity as a covariate. This approach was used in generating the LS mean values only and was not considered to be an additional statistical analysis, no additional statistical analyses are reported for this outcome measure.

FAS included all randomized participants who received at least 1 dose of the study drug and had at least 1 post-baseline efficacy assessment on the primary endpoint. Here, 'Number analyzed' signifies participants evaluable for this outcome measure at specified timepoints.

HIT-6 is a tool used to measure the impact headaches have on a participant's normal daily life and ability to function. The HIT-6 consists of 6 items, including pain, social functioning, role functioning, vitality, cognitive functioning, and psychological distress. Each item was answered on a 5-point Likert scale (6=never, 8=rarely, 10=sometimes, 11=very often, or 13=always), which were summed to produce a total score that ranged from 36 to 78, with larger scores reflecting greater impact of headache on the daily life of the participant.

FAS included all randomized participants who received at least 1 dose of the study drug and had at least 1 post-baseline efficacy assessment on the primary endpoint. Here, 'Overall number of participants analyzed' signifies participants evaluable for this outcome measure.

The PGIC scale is a validated generic tool for the assessment of overall change in the severity of illness following treatment. Participants rated how they felt during assigned time points compared with how they felt before receiving study drug on a 7-point scale, where 1 = No change (or it got worse); 2 = Almost the same, hardly any change at all; 3 = A little better, but no noticeable change; 4 = Somewhat better, but the change has not made any real difference; 5 = Moderately better, and a slight but noticeable change; 6 = Better, and a definite improvement that has made a real and worthwhile difference; and 7 = A great deal better, and a considerable improvement that has made all the difference. Responders were those with a scale of 5 to 7 and non-responders were those with a scale of 1 to 4.

FAS included all randomized participants who received at least 1 dose of the study drug and had at least 1 post-baseline efficacy assessment on the primary endpoint.

An adverse event (AE) was defined as any untoward medical occurrence in a participant who received study drug without regard to possibility of causal relationship. TEAEs were defined as AEs occurring at or after the first dose of the study drug. Serious AEs were defined as death, a life-threatening AE, inpatient hospitalization or prolongation of existing hospitalization, persistent or significant disability or incapacity, a congenital anomaly or birth defect, or an important medical event that jeopardized participant and required medical intervention to prevent 1 of the outcomes listed in this definition. A summary of other non-serious AEs and all serious AEs, regardless of causality is located in Reported AE section.

DB safety analysis set included all randomized participants who received at least 1 dose of study drug during the DB treatment period.

An AE was defined as any untoward medical occurrence in a participant who received study drug without regard to possibility of causal relationship. TEAEs were defined as AEs occurring at or after the first dose of the study drug. Serious AEs were defined as death, a life-threatening AE, inpatient hospitalization or prolongation of existing hospitalization, persistent or significant disability or incapacity, a congenital anomaly or birth defect, or an important medical event that jeopardized participant and required medical intervention to prevent 1 of the outcomes listed in this definition. A summary of other non-serious AEs and all serious AEs, regardless of causality is located in Reported AE section.

OL-ITT analysis set included only participants who received at least 1 dose of study drug during the open-label treatment period.

Number of participants who did not complete the study due to any reason and due to AEs are reported.

DB safety analysis set included all randomized participants who received at least 1 dose of study drug during the DB treatment period.

Number of participants who did not complete the study due to any reason and due to AEs are reported.

OL-ITT analysis set included only participants who received at least 1 dose of study drug during the open-label treatment period.

Concomitant medications included: agents acting on renin-angiotensin system, analgesics, anesthetics, anti-parkinson drugs, antianemic preparations, antibacterials for systemic use, antidiarrheals, intestinal antiinflammatory/antiinfective agents, antiemetics and antinauseants, antiepileptics, antifungals for dermatologiocal use, antihistamines for systemic use, antihypertensives, antiinflammatory and antirheumatics, antineoplastic agents, antiobesity preparations, antipruritics, antithrombotics, antivirals for systemic use, beta blocking agents, calcium channel blockers, cardiac therapy, corticosteroids, cough and cold preparations, diuretics, lipid modifying agents, nasal preparations, thyroid therapy, urologicals, vaccines, psycholeptics, psycoanaleptics, ophthalmologicals, general nutrients, mineral supplements, muscle relaxants, vitamins, drugs used in diabetes, sex hormones and modulators of the genital system, immunosuppresants, drugs for acid related disorders etc.

DB safety analysis set included all randomized participants who received at least 1 dose of study drug during the DB treatment period.

Concomitant medications included: agents acting on renin-angiotensin system, analgesics, anti-parkinson drugs, antianemic preparations, antibacterials for systemic use, antiemetics and antinauseants, antihistamines for systemic use, antihypertensives, antiinflammatory and antirheumatics, antineoplastic agents, antithrombotics, beta blocking agents, calcium channel blockers, corticosteroids for systemic use, cough and cold preparations, diuretics, lipid modifying agents, nasal preparations, other gynecologicals, other nervous system drugs, thyroid therapy, unspecified herbal and traditional medicine, urologicals, vaccines, psycholeptics, psycoanaleptics, general nutrients, mineral supplements, muscle relaxants, vitamins, sex hormones and modulators of the genital system, drugs for acid related disorders, drugs for constipation, drugs for obstructive airways disease etc.

OL-ITT analysis set included only participants who received at least 1 dose of study drug during the open-label treatment period.

eC-SSRS is a questionnaire to assess suicidal ideation (severity and intensity) and behavior. Suicidal ideation: A series of 1 -5 questions (with 'yes' or 'no' response) with 5 types of ideation of increasing severity: 1. wish to be dead, 2. non-specific active suicidal thoughts, 3. active suicidal ideation with any methods (not plan) without intent to act, 4. active suicidal ideation with some intent to act, without specific plan, 5. active suicidal ideation with specific plan and intent. A positive finding was defined as a 'yes' response to question 4 or 5.

Safety analysis set included all randomized participants who received at least 1 dose of study drug.

Number of participants with treatment-emergent antidrug antibodies reported.

ITT analysis set included all randomized participants.