Study to Evaluate Rilzabrutinib in Adults and Adolescents With Persistent or Chronic Immune Thrombocytopenia (ITP)

Durable platelet response per guidance in regions except European Union and United Kingdom was defined as platelet counts at or above 50,000/mcL for >=two-thirds of at least 8 non-missing weekly scheduled platelet measurements during the last 12 weeks of the 24-week blinded treatment period in the absence of rescue therapy, provided that at least 2 non-missing weekly scheduled platelet measurements were at or above 50,000/mcL during the last 6 weeks of the 24-week blinded treatment period.

Durable platelet response per guidance in European Union and United Kingdom was defined as platelet counts at or above 50,000/mcL for at least 8 out of the last 12 weeks of the 24-week blinded treatment period in the absence of rescue therapy.

Number of weeks with platelet response was assessed using clinically meaningful threshold of platelet count >=50,000/mcL or between >=30,000/mcL and <50,000/mcL and at least doubled from baseline over the 24-week blinded treatment period in the absence of rescue therapy.

Number of weeks with platelet response was assessed using clinically meaningful threshold of platelet counts >=30,000/mcL and at least doubled from baseline over the 24-week blinded treatment period in the absence of rescue therapy.

Time to first platelet count of >=50,000/mcL or between >=30,000/mcL and <50,000/mcL and doubled from baseline was calculated as: (date of first occurrence of platelet response - date of first study drug intake) + 1.

Resue therapy included intravenous immunoglobulin (Ig) or high-dose corticosteroids, platelet infusion, or anti-D Ig infusion. Percentage of participants who required rescue therapy are presented.

ITP-PAQ:38 items and 44 items completed by male and female respondents respectively.It included 10 scales:symptoms(6 items:1-6),fatigue/sleep(4 items:7-10),bother-physical health(3 items:11-13),activity(2 items:14-15),psychological health(5 items:16-20),fear(5 items:21-25),overall quality of life(QoL)(5 items:26-30),social activity(4 items:31-34),women's reproductive health(6 items:35-40),work(4 items:41-44).Responses were recorded on 4-point(1:"strongly disagree" to 4:"strongly agree"),5-point(1:"never/not at all" to 5:"all the time/extremely") or 7-point(1:"not at all" to 7:"extremely") Likert scales.Each item score:100x([possible maximal item score - item score]/range).All item scores:transformed to 0 to 100 continuum and were weighted equally to derive scale scores.Total score:0(worst) to 100(best);higher scores:better QoL.Change of positive value:improvement.Change from baseline in physical fatigue is presented.Baseline:last available value before first dose of DB study drug.

Per guidance in European Union and United Kingdom, ITP IBLS was a bleeding assessment system which comprised of 11 (10 for male) site-specific grades assessed at 9 anatomical sites by history (Hx) over previous period. In addition, 2 of these sites, skin and oral, were also assessed by physical examination (PE). These 11 grades included: skin (PE), skin (Hx), oral (PE), oral (Hx), epistaxis, gastrointestinal, urinary, gynecological, pulmonary, intracranial hemorrhage, and subconjunctival hemorrhage; scores ranged from 0 (none) to 2 (marked bleeding). For each participant, an IBLS score at each visit was calculated by taking average across 11 items (10 for male and postmenopausal female) at 9 sites (8 for male and postmenopausal female). Total score was calculated as mean value for all 11 grades ranging from 0 (best) to 22 (worst); higher scores indicated worse outcomes. Change of negative value indicates an improvement.Baseline:last available value before first dose of DB study drug.

Per guidance in European Union and United Kingdom, ITP IBLS was a bleeding assessment system which comprised of 11 (10 for male) site-specific grades assessed at 9 anatomical sites by Hx over previous period. In addition, 2 of these sites, skin and oral, were also assessed by PE. These 11 grades included: skin (PE), skin (Hx), oral (PE), oral (Hx), epistaxis, gastrointestinal, urinary, gynecological, pulmonary, intracranial hemorrhage, and subconjunctival hemorrhage; scores ranged from 0 (none) to 2 (marked bleeding). For each participant, an IBLS score at each visit was calculated by taking average across 11 items (10 for male) at 9 sites (8 for male). Total score was calculated as mean value for all 11 grades ranging from 0 (best) to 22 (worst); higher scores indicated worse outcomes. Change of negative value indicates an improvement. Baseline:last available value before first dose of DB study drug.

Stability of response was defined as the percentage of participants who were able to achieve stable platelet response defined as no 2 scheduled visits, at least 4 weeks apart, with a platelet count <50,000/mcL, without an intervening visit with a platelet count >=50,000/mcL, within a period of 24 weeks following initial achievement of the platelet response (initial platelet response defined as platelet count >=50,000/mcL within 12 weeks of initiation of treatment with rilzabrutinib during the study). This endpoint was assessed from start of DB period through OL period.

An AE was any untoward medical occurrence in a participant or clinical investigation participant, administered a study drug and which did not necessarily had a causal relationship with the study drug. An SAE was any AE 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 or was an important medical event. TEAEs were defined as AEs that developed, worsened or became serious during the TE period. Bleeding TEAEs Grade >=2 (criteria mentioned in statistical analysis plan) are also presented.

Blood samples were collected at specified timepoints for the analysis of plasma concentration of rilzabrutinib.

ITP-PAQ:38 items and 44 items completed by male and female respondents respectively.It included 10 scales:symptoms(6 items:1-6),fatigue/sleep(4 items:7-10),bother-physical health(3 items:11-13),activity(2 items:14-15),psychological health(5 items:16-20),fear(5 items:21-25),overall QoL(5 items:26-30),social activity(4 items:31-34),women's reproductive health(6 items:35-40),work(4 items:41-44).Responses were recorded on 4-point(1:"strongly disagree" to 4:"strongly agree"),5-point(1:"never/not at all" to 5:"all the time/extremely") or 7-point(1:"not at all" to 7:"extremely") Likert scales.Each item score:100x([possible maximal item score - item score]/range).All item scores:transformed to 0 to 100 continuum and were weighted equally to derive scale scores.Total score:0(worst) to 100(best);higher scores:better QoL.Change of positive value:improvement.Change from baseline in symptoms,bother and activity domains is presented.Baseline:last available value before first dose of DB study drug.

ITP-KIT was a disease-specific instrument and child self-report form designed to be completed by children >=7 years. It comprised of total of 27 items among which 26 items were structured as Likert scales with 5 response options 1: "never", 2: "rarely", 3: "sometimes", 4: "often" and 5: "always". An additional "not applicable" option was available for items 18 to 26, which was scored as 1: the same as "never". Item 27 was a descriptive question answered "yes" or "no" which was not included in the calculation of the summary score. Instrument yielded a summary KIT score which was the summation of the items calculated as: 100 x (1- [{sum of all valid responses - number of valid responses}/{number of valid responses*4}]). Scores were converted to a 0 to 100 with higher scores indicating better disease-specific QoL. Change from baseline of positive value indicated improvement. Baseline was defined as the last available value before first dose of DB study drug.