A Efficacy and Safety Study of Fostamatinib in the Treatment of Persistent/Chronic Immune Thrombocytopenic Purpura (ITP)

Stable platelet response by Week 24 defined as a platelet count of at least 50,000/µL on at least 4 of the 6 visits between Weeks 14-24

Platelet Count ≥ 50,000/µL at Week 12

Platelet Count ≥ 50,000/µL at Week 24

Among subjects with a baseline platelet count < 15,000/μL, achievement of a count ≥ 30,000/μL and at least 20,000/μL above baseline at Week 12.

Among subjects with a baseline platelet count < 15,000/μL, achievement of a count ≥ 30,000/μL and at least 20,000/μL above baseline at Week 24

The ITP Bleeding Scale (IBLS) is an immune thrombocytopenic purpura (ITP)-specific bleeding score used to analyze the correlation of clinical and laboratory platelet variables with bleeding. The IBLS comprises of 11 grades from 0 (none) to 2 (marked bleeding) by history over the previous week or by exam; 2 being worse. These 11 grades include: skin by physical exam, oral by physical exam, skin by history, oral by history, epistaxis, gastrointestinal, urinary, gynecological, pulmonary, intracranial hemorrhage, and subconjunctival hemorrhage. After each grade is scored, the mean value for all 11 grades is calculated (lowest score being 0 and highest score being 2) for each subject visit. LOCF method was used to impute any missing data.

The mean of the IBLS scores across visits during the 24-week treatment period was summarized by treatment group using descriptive statistics. A 2-sided, 2-sample t-test was used to test for a difference in means between treatments for this endpoint.

The World Health Organization (WHO) bleeding scale is a standardized grading scale created to measure the severity of bleeding. The scale is a clinical investigator-assessed five-point scale with a score range starting at the lowest 0=No bleeding, 1 = Petechiae, 2=Mild blood loss, 3=Gross blood loss, to the worse 4=Debilitating blood loss. The WHO bleeding scale is scored by history over the previous-week or by exam. After each grade is scored, the mean value is calculated (lowest score being 0 [no bleeding] to the highest score being 4 [debilitating blood loss]) for each visit. LOCF method was used to impute any missing data.

The mean of the WHO bleeding scale across visits during the 24-week treatment period was summarized by treatment group using descriptive statistics. A 2-sided, 2-sample t-test was used to test for a difference in means between treatments for this endpoint.