aTTP-related events were defined as: aTTP-related death, recurrence of aTTP (defined as recurrent thrombocytopenia requiring initiation of daily PE) or at least one major thromboembolic event (e.g., myocardial infarction, cerebrovascular accident, pulmonary embolism, or deep venous thrombosis). Percentage of participants with at least one aTTP-related events during the study were reported in this outcome measure.

aTTP-related events were defined as: aTTP-related death, recurrence of aTTP (defined as recurrent thrombocytopenia requiring initiation of daily PE) or at least one major thromboembolic event (e.g., myocardial infarction, cerebrovascular accident, pulmonary embolism or deep venous thrombosis).

Time to first aTTP-related events was defined as the duration of time (in days) from Baseline up to first aTTP-related event in LTS16371. Participants without an event during LTS16371 were censored at the end of the study. Kaplan-Meier method was used for the analysis.

Recurrence of aTTP was defined as recurrent thrombocytopenia requiring initiation of daily PE.

Recurrence of aTTP was defined as recurrent thrombocytopenia requiring initiation of daily PE.

Time to first recurrence of disease (aTTP) was defined as the duration of time (in days) from Baseline up to first recurrence of aTTP event in LTS16371. Recurrence of aTTP: defined as recurrent thrombocytopenia requiring initiation of daily PE. Participants without an event during LTS16371 were censored at the end of the study. Kaplan-Meier method was used for the analysis.

Major thromboembolic events (e.g., myocardial infarction, cerebrovascular accident, pulmonary embolism, or deep venous thrombosis) were assessed based on Standardized Medical Dictionary for Regulatory Activities (MedDRA) Query (SMQ). Reported major thromboembolic events included TTP recurrences.

Major thromboembolic events (e.g., myocardial infarction, cerebrovascular accident, pulmonary embolism, or deep venous thrombosis) were assessed based on SMQ. Reported major thromboembolic events included TTP recurrences.

Time to first major thromboembolic event was defined as the duration of time (in days) from Baseline up to first major thromboembolic event in LTS16371. Participants without an event during LTS16371 were censored at the end of the study. Kaplan-Meier method was used for the analysis.

The RBANS is a 30-minute comprehensive screening test with five individual domains (immediate memory, delayed memory, attention, language, and visuospatial ability) to examine the cognitive mental status of a participant. Scores from all individual domain were aggregated into a total score and thus RBANS total score ranged from 40 to 160, where higher scores reflected better performance.

HIT-6 is an easy to administer assessment that was used as a clinical evaluation of the impact of headache on a participant's QoL in both clinical practice and clinical research. The questionnaire included 6 questions covering the 6 areas of functioning most impacted in headache sufferers including pain, role functioning (the ability to carry out usual activities), social functioning, vitality (energy/ fatigue), cognitive functioning, and psychological/emotional distress. Total HIT-6 scores (sum of all individual questions) ranged from 36 (best outcome) to 78 (worst outcome), where higher scores indicated worse condition.

The SF-36 consisted of 36 items that was summarized into 8 domains: physical functioning, social functioning, role functioning/physical, role functioning/emotional, emotional well-being, energy/fatigue, pain, general health and an additional single item covering change in health status. Physical functioning domain scores ranged from 0 (worst value) to 100 (best value), with higher scores reflecting better health status. Change from baseline in physical functioning domain score at months 12, 24, and 36 were reported in this outcome measure.

The SF-36 consisted of 36 items that was summarized into 8 domains: physical functioning, social functioning, role functioning/physical, role functioning/emotional, emotional well-being, energy/fatigue, pain, general health and an additional single item covering change in health status. Role Functioning/Physical domain scores ranged from 0 (worst value) to 100 (best value), with higher scores reflecting better health status. Change from baseline in role functioning/physical domain score at months 12, 24, and 36 were reported in this outcome measure.

The SF-36 consisted of 36 items that was summarized into 8 domains: physical functioning, social functioning, role functioning/physical, role functioning/emotional, emotional well-being, energy/fatigue, pain, general health and an additional single item covering change in health status. Role functioning/emotional domain scores ranged from 0 (worst value) to 100 (best value), with higher scores reflecting better health status. Change from baseline in role functioning/emotional domain score at months 12, 24, and 36 were reported in this outcome measure.

The SF-36 consisted of 36 items that was summarized into 8 domains: physical functioning, social functioning, role functioning/physical, role functioning/emotional, emotional well-being, energy/fatigue, pain, general health and an additional single item covering change in health status. Energy/fatigue domain scores ranged from 0 (worst value) to 100 (best value), with higher scores reflecting better health status. Change from baseline in energy/fatigue domain score at months 12, 24, and 36 were reported in this outcome measure.

The SF-36 consisted of 36 items that was summarized into 8 domains: physical functioning, social functioning, role functioning/physical, role functioning/emotional, emotional well-being, energy/fatigue, pain, general health and an additional single item covering change in health status. Emotional well-being domain scores ranged from 0 (worst value) to 100 (best value), with higher scores reflecting better health status. Change from baseline in emotional well-being domain score at months 12, 24, and 36 were reported in this outcome measure.

The SF-36 consisted of 36 items that was summarized into 8 domains: physical functioning, social functioning, role functioning/physical, role functioning/emotional, emotional well-being, energy/fatigue, pain, general health and an additional single item covering change in health status. Social functioning domain scores ranged from 0 (worst value) to 100 (best value), with higher scores reflecting better health status. Change from baseline in social functioning domain score at months 12, 24, and 36 were reported in this outcome measure.

The SF-36 consisted of 36 items that was summarized into 8 domains: physical functioning, social functioning, role functioning/physical, role functioning/emotional, emotional well-being, energy/fatigue, pain, general health and an additional single item covering change in health status. Pain domain scores ranged from 0 (worst value) to 100 (best value), with higher scores reflecting better health status. Change from baseline in pain domain score at months 12, 24, and 36 were reported in this outcome measure.

The SF-36 consisted of 36 items that was summarized into 8 domains: physical functioning, social functioning, role functioning/physical, role functioning/emotional, emotional well-being, energy/fatigue, pain, general health and an additional single item covering change in health status. General Health domain scores ranged from 0 (worst value) to 100 (best value), with higher scores reflecting better health status. Change from baseline in general health domain score at months 12, 24, and 36 were reported in this outcome measure.

The SF-36 consisted of 36 items that was summarized into 8 domains: physical functioning, social functioning, role functioning/physical, role functioning/emotional, emotional well-being, energy/fatigue, pain, general health and an additional single item covering change in health status. Change in health status scores ranged from 0 (worst value) to 100 (best value), with higher scores reflecting better health status. Change from baseline in change in health status score at months 12, 24, and 36 were reported in this outcome measure.

Drug-induced TE ADA positive was based on the outcome of a tiered assay approach that included a modified ADA (mADA) method to eliminate the effects of pre-existing antibodies (pre-Ab). TE ADA responses reported here included both pre-Ab positive and negative responses. A participant was considered as drug-induced TE ADA positive if post-dose samples were positive, regardless of the status of pre-dose samples in the ADA and modified ADA assay.

An AE was any untoward medical occurrence in a clinical study participant administered a medicinal product and which did not necessarily had to have a causal relationship with the treatment. An SAE was any untoward medical occurrence that at any dose: resulted in death, was life-threatening, required inpatient hospitalization or prolongation of existing hospitalization, resulted in persistent or significant disability/incapacity, was a congenital anomaly/birth defect, was a medically important event.

Platelet count response was defined as initial platelet count ≥ 150,000/μL with subsequent stop of daily PE within 5 days. It refers to the first time both conditions, platelet count ≥ 150,000/μL and the stop of daily PE within 5 days, were met.

Time-to-response, defined by the achievement of platelet count response, confirmed at 48 hours after the initial reporting of this response. Platelet response was defined as recovery of platelets ≥ 150,000/µL. This response had to be confirmed at 48 hours after the initial reporting of platelet recovery ≥ 150,000/µL by a de novo measure of platelets ≥ 150,000/µL and lactate dehydrogenase (LDH) ≤ 2x upper limit of normal (ULN) (i.e., 'confirmed platelet response').