Trial Outcomes & Findings for A Study of INCB050465 in Combination With Ruxolitinib in Subjects With Myelofibrosis (NCT NCT02718300)

Last Updated: 2024-05-01

Results Overview

DLTs were defined as the occurrence of any protocol-defined toxicities occurring up to and including Day 28, except those with a clear alternative explanation (e.g., disease progression, other medications) or transient (≤ 72 hours) abnormal laboratory values without associated clinically significant signs or symptoms based on investigator determination. All DLTs were assessed by the investigator using Common Terminology Criteria for Adverse Events (CTCAE) version 4.03 criteria.

Recruitment status

TERMINATED

Study phase

PHASE2

Target enrollment

74 participants

Primary outcome timeframe

up to Day 28

Results posted on

2024-05-01

Participant Flow

This study was conducted at 20 study centers in the United States. Participants who initially received weekly doses were given the option of transitioning to daily doses based on a preliminary analysis of data. All participants were analyzed according to their original treatment assignment in the Participant Flow and Baseline Characteristic module; those participants who transitioned from weekly to daily doses (n=8) were analyzed separately for specific outcome measures.

Participant milestones

Participant milestones
Measure	TG5I/M Participants received at least 6 months of prior ruxolitinib therapy, including ruxolitinib administration at a stable dose of 5 milligrams (mg) twice a day (BID) to 25 mg BID for at least 8 weeks before randomization. From Day 1 to the end of Week 8, participants received oral parsaclisib 20 mg once daily (QD), followed by 5 mg QD until discontinuation criteria were met, in combination with the pre-Day 1 stable dose of ruxolitinib (5 to 25 mg BID).	TG5D Participants received at least 6 months of prior ruxolitinib therapy, including ruxolitinib administration at a stable dose of 5 mg BID to 25 mg BID for at least 8 weeks before randomization. From Day 1, participants received oral parsaclisib 5 mg QD until discontinuation criteria were met, in combination with the pre-Day 1 stable dose of ruxolitinib (5 to 25 mg BID).	TG10 + TG20: Daily/Weekly Dosing Participants received at least 6 months of prior ruxolitinib therapy, including ruxolitinib administration at a stable dose of 5 mg BID to 25 mg BID for at least 8 weeks before randomization. From Day 1 to the end of Week 8, participants in TG10 and TG20 received oral parsaclisib 10 mg or 20 mg QD, respectively, followed by the same dose weekly until discontinuation criteria were met, in combination with the pre-Day 1 stable dose of ruxolitinib (5 to 25 mg BID).
Overall Study STARTED	21	21	32
Overall Study COMPLETED	0	0	0
Overall Study NOT COMPLETED	21	21	32

Reasons for withdrawal

Reasons for withdrawal
Measure	TG5I/M Participants received at least 6 months of prior ruxolitinib therapy, including ruxolitinib administration at a stable dose of 5 milligrams (mg) twice a day (BID) to 25 mg BID for at least 8 weeks before randomization. From Day 1 to the end of Week 8, participants received oral parsaclisib 20 mg once daily (QD), followed by 5 mg QD until discontinuation criteria were met, in combination with the pre-Day 1 stable dose of ruxolitinib (5 to 25 mg BID).	TG5D Participants received at least 6 months of prior ruxolitinib therapy, including ruxolitinib administration at a stable dose of 5 mg BID to 25 mg BID for at least 8 weeks before randomization. From Day 1, participants received oral parsaclisib 5 mg QD until discontinuation criteria were met, in combination with the pre-Day 1 stable dose of ruxolitinib (5 to 25 mg BID).	TG10 + TG20: Daily/Weekly Dosing Participants received at least 6 months of prior ruxolitinib therapy, including ruxolitinib administration at a stable dose of 5 mg BID to 25 mg BID for at least 8 weeks before randomization. From Day 1 to the end of Week 8, participants in TG10 and TG20 received oral parsaclisib 10 mg or 20 mg QD, respectively, followed by the same dose weekly until discontinuation criteria were met, in combination with the pre-Day 1 stable dose of ruxolitinib (5 to 25 mg BID).
Overall Study Death	4	5	17
Overall Study Lost to Follow-up	1	0	2
Overall Study Physician Decision	1	0	2
Overall Study Study Terminated by Sponsor	6	3	4
Overall Study Withdrawal by Subject	0	4	3
Overall Study Transitioned to Rollover Study or Pursued Allogenic Transplant	9	9	4

Baseline Characteristics

A Study of INCB050465 in Combination With Ruxolitinib in Subjects With Myelofibrosis

Baseline characteristics by cohort

Baseline characteristics by cohort
Measure	TG5I/M n=21 Participants Participants received at least 6 months of prior ruxolitinib therapy, including ruxolitinib administration at a stable dose of 5 milligrams (mg) twice a day (BID) to 25 mg BID for at least 8 weeks before randomization. From Day 1 to the end of Week 8, participants received oral parsaclisib 20 mg once daily (QD), followed by 5 mg QD until discontinuation criteria were met, in combination with the pre-Day 1 stable dose of ruxolitinib (5 to 25 mg BID).	TG5D n=21 Participants Participants received at least 6 months of prior ruxolitinib therapy, including ruxolitinib administration at a stable dose of 5 mg BID to 25 mg BID for at least 8 weeks before randomization. From Day 1, participants received oral parsaclisib 5 mg QD until discontinuation criteria were met, in combination with the pre-Day 1 stable dose of ruxolitinib (5 to 25 mg BID).	TG10 + TG20: Daily/Weekly Dosing n=32 Participants Participants received at least 6 months of prior ruxolitinib therapy, including ruxolitinib administration at a stable dose of 5 mg BID to 25 mg BID for at least 8 weeks before randomization. From Day 1 to the end of Week 8, participants in TG10 and TG20 received oral parsaclisib 10 mg or 20 mg QD, respectively, followed by the same dose weekly until discontinuation criteria were met, in combination with the pre-Day 1 stable dose of ruxolitinib (5 to 25 mg BID).	Total n=74 Participants Total of all reporting groups
Age, Continuous	67.9 years STANDARD_DEVIATION 7.33 • n=5 Participants	69.3 years STANDARD_DEVIATION 7.96 • n=7 Participants	66.0 years STANDARD_DEVIATION 8.94 • n=5 Participants	67.5 years STANDARD_DEVIATION 8.25 • n=4 Participants
Sex: Female, Male Female	11 Participants n=5 Participants	11 Participants n=7 Participants	17 Participants n=5 Participants	39 Participants n=4 Participants
Sex: Female, Male Male	10 Participants n=5 Participants	10 Participants n=7 Participants	15 Participants n=5 Participants	35 Participants n=4 Participants
Ethnicity (NIH/OMB) Hispanic or Latino	0 Participants n=5 Participants	2 Participants n=7 Participants	3 Participants n=5 Participants	5 Participants n=4 Participants
Ethnicity (NIH/OMB) Not Hispanic or Latino	18 Participants n=5 Participants	19 Participants n=7 Participants	27 Participants n=5 Participants	64 Participants n=4 Participants
Ethnicity (NIH/OMB) Unknown or Not Reported	3 Participants n=5 Participants	0 Participants n=7 Participants	2 Participants n=5 Participants	5 Participants n=4 Participants
Race/Ethnicity, Customized White	20 Participants n=5 Participants	15 Participants n=7 Participants	25 Participants n=5 Participants	60 Participants n=4 Participants
Race/Ethnicity, Customized Black or African American	1 Participants n=5 Participants	2 Participants n=7 Participants	0 Participants n=5 Participants	3 Participants n=4 Participants
Race/Ethnicity, Customized Asian	0 Participants n=5 Participants	2 Participants n=7 Participants	3 Participants n=5 Participants	5 Participants n=4 Participants
Race/Ethnicity, Customized Captured as "Other" in Database	0 Participants n=5 Participants	2 Participants n=7 Participants	4 Participants n=5 Participants	6 Participants n=4 Participants

PRIMARY outcome

Timeframe: up to Day 28

Population: Initial Safety Population: all participants who received at least 1 dose of study drug. Treatment groups were determined according to the actual treatment the participant received regardless of assigned study drug treatment. Analysis was conducted on the Safety Population during the initial safety period. Due to early termination of the study, per the Statistical Analysis Plan, daily and weekly dosing arms were combined for analysis.

Outcome measures

Outcome measures
Measure	TG5I/M n=21 Participants Participants received at least 6 months of prior ruxolitinib therapy, including ruxolitinib administration at a stable dose of 5 milligrams (mg) twice a day (BID) to 25 mg BID for at least 8 weeks before randomization. From Day 1 to the end of Week 8, participants received oral parsaclisib 20 mg once daily (QD), followed by 5 mg QD until discontinuation criteria were met, in combination with the pre-Day 1 stable dose of ruxolitinib (5 to 25 mg BID).	TG5D n=21 Participants Participants received at least 6 months of prior ruxolitinib therapy, including ruxolitinib administration at a stable dose of 5 mg BID to 25 mg BID for at least 8 weeks before randomization. From Day 1, participants received oral parsaclisib 5 mg QD until discontinuation criteria were met, in combination with the pre-Day 1 stable dose of ruxolitinib (5 to 25 mg BID).	TG10 + TG20: Daily/Weekly Dosing n=32 Participants Participants received at least 6 months of prior ruxolitinib therapy, including ruxolitinib administration at a stable dose of 5 mg BID to 25 mg BID for at least 8 weeks before randomization. From Day 1 to the end of Week 8, participants in TG10 and TG20 received oral parsaclisib 10 mg or 20 mg QD, respectively, followed by the same dose weekly until discontinuation criteria were met, in combination with the pre-Day 1 stable dose of ruxolitinib (5 to 25 mg BID).	Ruxolitinib 20 mg Throughout the study, participants received a stable dose of ruxolitinib 20 mg BID.	Ruxolitinib 25 mg Throughout the study, participants received a stable dose of ruxolitinib 25 mg BID.
Number of Participants With Dose-limiting Toxicities (DLTs)	0 Participants	0 Participants	0 Participants	—	—

PRIMARY outcome

Timeframe: Baseline; Week 12

Population: Initial Safety Population: all enrolled participants who received at least 1 dose of study drug. Analysis was conducted on the Safety Population during the initial safety period. Only participants with available data were analyzed. Due to early termination of the study, per the Statistical Analysis Plan, daily and weekly dosing arms were combined for efficacy analysis.

Change from Baseline was calculated as the post-Baseline value minus the Baseline value.

Outcome measures

Outcome measures
Measure	TG5I/M n=20 Participants Participants received at least 6 months of prior ruxolitinib therapy, including ruxolitinib administration at a stable dose of 5 milligrams (mg) twice a day (BID) to 25 mg BID for at least 8 weeks before randomization. From Day 1 to the end of Week 8, participants received oral parsaclisib 20 mg once daily (QD), followed by 5 mg QD until discontinuation criteria were met, in combination with the pre-Day 1 stable dose of ruxolitinib (5 to 25 mg BID).	TG5D n=17 Participants Participants received at least 6 months of prior ruxolitinib therapy, including ruxolitinib administration at a stable dose of 5 mg BID to 25 mg BID for at least 8 weeks before randomization. From Day 1, participants received oral parsaclisib 5 mg QD until discontinuation criteria were met, in combination with the pre-Day 1 stable dose of ruxolitinib (5 to 25 mg BID).	TG10 + TG20: Daily/Weekly Dosing n=29 Participants Participants received at least 6 months of prior ruxolitinib therapy, including ruxolitinib administration at a stable dose of 5 mg BID to 25 mg BID for at least 8 weeks before randomization. From Day 1 to the end of Week 8, participants in TG10 and TG20 received oral parsaclisib 10 mg or 20 mg QD, respectively, followed by the same dose weekly until discontinuation criteria were met, in combination with the pre-Day 1 stable dose of ruxolitinib (5 to 25 mg BID).	Ruxolitinib 20 mg Throughout the study, participants received a stable dose of ruxolitinib 20 mg BID.	Ruxolitinib 25 mg Throughout the study, participants received a stable dose of ruxolitinib 25 mg BID.
Change From Baseline in Spleen Volume Through Week 12 of the Initial Study Period as Measured by Magnetic Resonance Imaging (MRI) (or Computed Tomography [CT] Scan in Applicable Participants) Baseline	1779.0 centimeters cubed (cm^3) Standard Deviation 1006.75	2032.3 centimeters cubed (cm^3) Standard Deviation 773.45	2469.0 centimeters cubed (cm^3) Standard Deviation 1208.90	—	—
Change From Baseline in Spleen Volume Through Week 12 of the Initial Study Period as Measured by Magnetic Resonance Imaging (MRI) (or Computed Tomography [CT] Scan in Applicable Participants) Change from Baseline at Week 12	383.3 centimeters cubed (cm^3) Standard Deviation 2342.09	-276.9 centimeters cubed (cm^3) Standard Deviation 226.11	-54.3 centimeters cubed (cm^3) Standard Deviation 312.69	—	—

PRIMARY outcome

Timeframe: Baseline; Week 12

Population: Initial Safety Population. Analysis was conducted on the Safety Population during the initial safety period. Only participants with available data were analyzed. Due to early termination of the study, per the Statistical Analysis Plan, daily and weekly dosing arms were combined for efficacy analysis.

Percent change from Baseline was calculated as the (\[post-Baseline value minus the Baseline value\] / Baseline value) x 100.

Outcome measures

Outcome measures
Measure	TG5I/M n=20 Participants Participants received at least 6 months of prior ruxolitinib therapy, including ruxolitinib administration at a stable dose of 5 milligrams (mg) twice a day (BID) to 25 mg BID for at least 8 weeks before randomization. From Day 1 to the end of Week 8, participants received oral parsaclisib 20 mg once daily (QD), followed by 5 mg QD until discontinuation criteria were met, in combination with the pre-Day 1 stable dose of ruxolitinib (5 to 25 mg BID).	TG5D n=17 Participants Participants received at least 6 months of prior ruxolitinib therapy, including ruxolitinib administration at a stable dose of 5 mg BID to 25 mg BID for at least 8 weeks before randomization. From Day 1, participants received oral parsaclisib 5 mg QD until discontinuation criteria were met, in combination with the pre-Day 1 stable dose of ruxolitinib (5 to 25 mg BID).	TG10 + TG20: Daily/Weekly Dosing n=28 Participants Participants received at least 6 months of prior ruxolitinib therapy, including ruxolitinib administration at a stable dose of 5 mg BID to 25 mg BID for at least 8 weeks before randomization. From Day 1 to the end of Week 8, participants in TG10 and TG20 received oral parsaclisib 10 mg or 20 mg QD, respectively, followed by the same dose weekly until discontinuation criteria were met, in combination with the pre-Day 1 stable dose of ruxolitinib (5 to 25 mg BID).	Ruxolitinib 20 mg Throughout the study, participants received a stable dose of ruxolitinib 20 mg BID.	Ruxolitinib 25 mg Throughout the study, participants received a stable dose of ruxolitinib 25 mg BID.
Percent Change From Baseline in Spleen Volume Through Week 12 as Measured by MRI (or CT Scan in Applicable Participants)	9.2 percent change Standard Deviation 104.37	-15.2 percent change Standard Deviation 10.89	-3.1 percent change Standard Deviation 12.21	—	—

SECONDARY outcome

Timeframe: Baseline; Week 24

Change from Baseline was calculated as the post-Baseline value minus the Baseline value.

Outcome measures

Outcome measures
Measure	TG5I/M n=20 Participants Participants received at least 6 months of prior ruxolitinib therapy, including ruxolitinib administration at a stable dose of 5 milligrams (mg) twice a day (BID) to 25 mg BID for at least 8 weeks before randomization. From Day 1 to the end of Week 8, participants received oral parsaclisib 20 mg once daily (QD), followed by 5 mg QD until discontinuation criteria were met, in combination with the pre-Day 1 stable dose of ruxolitinib (5 to 25 mg BID).	TG5D n=17 Participants Participants received at least 6 months of prior ruxolitinib therapy, including ruxolitinib administration at a stable dose of 5 mg BID to 25 mg BID for at least 8 weeks before randomization. From Day 1, participants received oral parsaclisib 5 mg QD until discontinuation criteria were met, in combination with the pre-Day 1 stable dose of ruxolitinib (5 to 25 mg BID).	TG10 + TG20: Daily/Weekly Dosing n=29 Participants Participants received at least 6 months of prior ruxolitinib therapy, including ruxolitinib administration at a stable dose of 5 mg BID to 25 mg BID for at least 8 weeks before randomization. From Day 1 to the end of Week 8, participants in TG10 and TG20 received oral parsaclisib 10 mg or 20 mg QD, respectively, followed by the same dose weekly until discontinuation criteria were met, in combination with the pre-Day 1 stable dose of ruxolitinib (5 to 25 mg BID).	Ruxolitinib 20 mg Throughout the study, participants received a stable dose of ruxolitinib 20 mg BID.	Ruxolitinib 25 mg Throughout the study, participants received a stable dose of ruxolitinib 25 mg BID.
Change From Baseline in Spleen Volume Through Week 24 of the Initial Study Period as Measured by MRI (or CT Scan in Applicable Participants) Baseline	1779.0 cm^3 Standard Deviation 1006.75	2032.3 cm^3 Standard Deviation 773.45	2469.0 cm^3 Standard Deviation 1208.90	—	—
Change From Baseline in Spleen Volume Through Week 24 of the Initial Study Period as Measured by MRI (or CT Scan in Applicable Participants) Change from Baseline at Week 24	-292.6 cm^3 Standard Deviation 514.91	-335.9 cm^3 Standard Deviation 204.19	-37.5 cm^3 Standard Deviation 432.02	—	—

SECONDARY outcome

Timeframe: Baseline; Week 24

Percent change from Baseline was calculated as the (\[post-Baseline value minus the Baseline value\] / Baseline value) x 100.

Outcome measures

Outcome measures
Measure	TG5I/M n=15 Participants Participants received at least 6 months of prior ruxolitinib therapy, including ruxolitinib administration at a stable dose of 5 milligrams (mg) twice a day (BID) to 25 mg BID for at least 8 weeks before randomization. From Day 1 to the end of Week 8, participants received oral parsaclisib 20 mg once daily (QD), followed by 5 mg QD until discontinuation criteria were met, in combination with the pre-Day 1 stable dose of ruxolitinib (5 to 25 mg BID).	TG5D n=14 Participants Participants received at least 6 months of prior ruxolitinib therapy, including ruxolitinib administration at a stable dose of 5 mg BID to 25 mg BID for at least 8 weeks before randomization. From Day 1, participants received oral parsaclisib 5 mg QD until discontinuation criteria were met, in combination with the pre-Day 1 stable dose of ruxolitinib (5 to 25 mg BID).	TG10 + TG20: Daily/Weekly Dosing n=20 Participants Participants received at least 6 months of prior ruxolitinib therapy, including ruxolitinib administration at a stable dose of 5 mg BID to 25 mg BID for at least 8 weeks before randomization. From Day 1 to the end of Week 8, participants in TG10 and TG20 received oral parsaclisib 10 mg or 20 mg QD, respectively, followed by the same dose weekly until discontinuation criteria were met, in combination with the pre-Day 1 stable dose of ruxolitinib (5 to 25 mg BID).	Ruxolitinib 20 mg Throughout the study, participants received a stable dose of ruxolitinib 20 mg BID.	Ruxolitinib 25 mg Throughout the study, participants received a stable dose of ruxolitinib 25 mg BID.
Percent Change From Baseline in Spleen Volume Through Week 24 as Measured by MRI (or CT Scan in Applicable Participants )	-21.9 percent change Standard Deviation 24.10	-19.0 percent change Standard Deviation 11.23	-4.9 percent change Standard Deviation 18.81	—	—

SECONDARY outcome

Timeframe: Baseline; Week 12

The MFSAF v3.0 is comprised of 19 individual symptom scores, each collected daily using an 11-point scale. The daily TSS is composed of 6 of these individual symptom scores (nights sweats, itchiness, abdominal discomfort, pain under left ribs, early satiety, bone/muscle pain) collected on the same day. Participants scored each symptom using a scale from 0 (absent) to 10 (worst imaginable). The TSS was calculated as a sum of all 6 symptom scores; scores ranged from 0 to 60, with higher scores corresponding to more severe symptoms. The Baseline TSS was defined as the average of daily total scores from the last 7 days before the first dose of INCB050465. The Week 12 TSS was the average of the daily total scores from the last 7 consecutive days before the Week 12 visit. Change from Baseline was calculated as the post-Baseline score minus the Baseline score.

Outcome measures

Outcome measures
Measure	TG5I/M n=16 Participants Participants received at least 6 months of prior ruxolitinib therapy, including ruxolitinib administration at a stable dose of 5 milligrams (mg) twice a day (BID) to 25 mg BID for at least 8 weeks before randomization. From Day 1 to the end of Week 8, participants received oral parsaclisib 20 mg once daily (QD), followed by 5 mg QD until discontinuation criteria were met, in combination with the pre-Day 1 stable dose of ruxolitinib (5 to 25 mg BID).	TG5D n=16 Participants Participants received at least 6 months of prior ruxolitinib therapy, including ruxolitinib administration at a stable dose of 5 mg BID to 25 mg BID for at least 8 weeks before randomization. From Day 1, participants received oral parsaclisib 5 mg QD until discontinuation criteria were met, in combination with the pre-Day 1 stable dose of ruxolitinib (5 to 25 mg BID).	TG10 + TG20: Daily/Weekly Dosing n=28 Participants Participants received at least 6 months of prior ruxolitinib therapy, including ruxolitinib administration at a stable dose of 5 mg BID to 25 mg BID for at least 8 weeks before randomization. From Day 1 to the end of Week 8, participants in TG10 and TG20 received oral parsaclisib 10 mg or 20 mg QD, respectively, followed by the same dose weekly until discontinuation criteria were met, in combination with the pre-Day 1 stable dose of ruxolitinib (5 to 25 mg BID).	Ruxolitinib 20 mg Throughout the study, participants received a stable dose of ruxolitinib 20 mg BID.	Ruxolitinib 25 mg Throughout the study, participants received a stable dose of ruxolitinib 25 mg BID.
Change From Baseline in the Total Symptom Score (TSS) Through Week 12 as Measured by Myelofibrosis Symptom Assessment Form (MFSAF) Version 3.0 (v3.0) Symptom Diary Baseline	17.6 scores on a scale Standard Deviation 10.59	16.3 scores on a scale Standard Deviation 12.82	15.2 scores on a scale Standard Deviation 12.94	—	—
Change From Baseline in the Total Symptom Score (TSS) Through Week 12 as Measured by Myelofibrosis Symptom Assessment Form (MFSAF) Version 3.0 (v3.0) Symptom Diary Change from Baseline at Week 12	-6.0 scores on a scale Standard Deviation 6.63	-5.0 scores on a scale Standard Deviation 11.15	-2.1 scores on a scale Standard Deviation 4.87	—	—

SECONDARY outcome

Timeframe: Baseline; Week 12

The MFSAF v3.0 is comprised of 19 individual symptom scores, each collected daily using an 11-point scale. The daily TSS is composed of 6 of these individual symptom scores (nights sweats, itchiness, abdominal discomfort, pain under left ribs, early satiety, bone/muscle pain) collected on the same day. Participants scored each symptom using a scale from 0 (absent) to 10 (worst imaginable). The TSS was calculated as a sum of all 6 symptom scores; scores ranged from 0 to 60, with higher scores corresponding to more severe symptoms. The Baseline TSS was defined as the average of daily total scores from the last 7 days before the first dose of INCB050465. The Week 12 TSS was the average of the daily total scores from the last 7 consecutive days before the Week 12 visit. Percent change from Baseline was calculated as the (\[post-Baseline value minus the Baseline value\] / Baseline value) x 100.

Outcome measures

Outcome measures
Measure	TG5I/M n=12 Participants Participants received at least 6 months of prior ruxolitinib therapy, including ruxolitinib administration at a stable dose of 5 milligrams (mg) twice a day (BID) to 25 mg BID for at least 8 weeks before randomization. From Day 1 to the end of Week 8, participants received oral parsaclisib 20 mg once daily (QD), followed by 5 mg QD until discontinuation criteria were met, in combination with the pre-Day 1 stable dose of ruxolitinib (5 to 25 mg BID).	TG5D n=12 Participants Participants received at least 6 months of prior ruxolitinib therapy, including ruxolitinib administration at a stable dose of 5 mg BID to 25 mg BID for at least 8 weeks before randomization. From Day 1, participants received oral parsaclisib 5 mg QD until discontinuation criteria were met, in combination with the pre-Day 1 stable dose of ruxolitinib (5 to 25 mg BID).	TG10 + TG20: Daily/Weekly Dosing n=21 Participants Participants received at least 6 months of prior ruxolitinib therapy, including ruxolitinib administration at a stable dose of 5 mg BID to 25 mg BID for at least 8 weeks before randomization. From Day 1 to the end of Week 8, participants in TG10 and TG20 received oral parsaclisib 10 mg or 20 mg QD, respectively, followed by the same dose weekly until discontinuation criteria were met, in combination with the pre-Day 1 stable dose of ruxolitinib (5 to 25 mg BID).	Ruxolitinib 20 mg Throughout the study, participants received a stable dose of ruxolitinib 20 mg BID.	Ruxolitinib 25 mg Throughout the study, participants received a stable dose of ruxolitinib 25 mg BID.
Percent Change From Baseline in the TSS Through Week 12 as Measured by MFSAF v3.0 Symptom Diary	-37.0 percent change Standard Deviation 30.93	-17.7 percent change Standard Deviation 57.81	10.1 percent change Standard Deviation 118.94	—	—

SECONDARY outcome

Timeframe: Baseline; Week 24

The MFSAF v3.0 is comprised of 19 individual symptom scores, each collected daily using an 11-point scale. The daily TSS is composed of 6 of these individual symptom scores (nights sweats, itchiness, abdominal discomfort, pain under left ribs, early satiety, bone/muscle pain) collected on the same day. Participants scored each symptom using a scale from 0 (absent) to 10 (worst imaginable). The TSS was calculated as a sum of all 6 symptom scores; scores ranged from 0 to 60, with higher scores corresponding to more severe symptoms. The Baseline TSS was defined as the average of daily total scores from the last 7 days before the first dose of INCB050465. The Week 24 TSS was the average of the daily total scores from the last 7 consecutive days before the Week 24 visit. Change from Baseline was calculated as the post-Baseline score minus the Baseline score.

Outcome measures

Outcome measures
Measure	TG5I/M n=16 Participants Participants received at least 6 months of prior ruxolitinib therapy, including ruxolitinib administration at a stable dose of 5 milligrams (mg) twice a day (BID) to 25 mg BID for at least 8 weeks before randomization. From Day 1 to the end of Week 8, participants received oral parsaclisib 20 mg once daily (QD), followed by 5 mg QD until discontinuation criteria were met, in combination with the pre-Day 1 stable dose of ruxolitinib (5 to 25 mg BID).	TG5D n=16 Participants Participants received at least 6 months of prior ruxolitinib therapy, including ruxolitinib administration at a stable dose of 5 mg BID to 25 mg BID for at least 8 weeks before randomization. From Day 1, participants received oral parsaclisib 5 mg QD until discontinuation criteria were met, in combination with the pre-Day 1 stable dose of ruxolitinib (5 to 25 mg BID).	TG10 + TG20: Daily/Weekly Dosing n=28 Participants Participants received at least 6 months of prior ruxolitinib therapy, including ruxolitinib administration at a stable dose of 5 mg BID to 25 mg BID for at least 8 weeks before randomization. From Day 1 to the end of Week 8, participants in TG10 and TG20 received oral parsaclisib 10 mg or 20 mg QD, respectively, followed by the same dose weekly until discontinuation criteria were met, in combination with the pre-Day 1 stable dose of ruxolitinib (5 to 25 mg BID).	Ruxolitinib 20 mg Throughout the study, participants received a stable dose of ruxolitinib 20 mg BID.	Ruxolitinib 25 mg Throughout the study, participants received a stable dose of ruxolitinib 25 mg BID.
Change From Baseline in the TSS Through Week 24 as Measured by MFSAF v3.0 Symptom Diary Baseline	17.6 scores on a scale Standard Deviation 10.59	16.3 scores on a scale Standard Deviation 12.82	15.2 scores on a scale Standard Deviation 12.94	—	—
Change From Baseline in the TSS Through Week 24 as Measured by MFSAF v3.0 Symptom Diary Change from Baseline at Week 24	-5.6 scores on a scale Standard Deviation 8.97	-3.9 scores on a scale Standard Deviation 13.63	-2.0 scores on a scale Standard Deviation 7.15	—	—

SECONDARY outcome

Timeframe: Baseline; Week 24

The MFSAF v3.0 is comprised of 19 individual symptom scores, each collected daily using an 11-point scale. The daily TSS is composed of 6 of these individual symptom scores (nights sweats, itchiness, abdominal discomfort, pain under left ribs, early satiety, bone/muscle pain) collected on the same day. Participants scored each symptom using a scale from 0 (absent) to 10 (worst imaginable). The TSS was calculated as a sum of all 6 symptom scores; scores ranged from 0 to 60, with higher scores corresponding to more severe symptoms. The Baseline TSS was defined as the average of daily total scores from the last 7 days before the first dose of INCB050465. The Week 24 TSS was the average of the daily total scores from the last 7 consecutive days before the Week 24 visit. Percent change from Baseline was calculated as the (\[post-Baseline value minus the Baseline value\] / Baseline value) x 100.

Outcome measures

Outcome measures
Measure	TG5I/M n=8 Participants Participants received at least 6 months of prior ruxolitinib therapy, including ruxolitinib administration at a stable dose of 5 milligrams (mg) twice a day (BID) to 25 mg BID for at least 8 weeks before randomization. From Day 1 to the end of Week 8, participants received oral parsaclisib 20 mg once daily (QD), followed by 5 mg QD until discontinuation criteria were met, in combination with the pre-Day 1 stable dose of ruxolitinib (5 to 25 mg BID).	TG5D n=10 Participants Participants received at least 6 months of prior ruxolitinib therapy, including ruxolitinib administration at a stable dose of 5 mg BID to 25 mg BID for at least 8 weeks before randomization. From Day 1, participants received oral parsaclisib 5 mg QD until discontinuation criteria were met, in combination with the pre-Day 1 stable dose of ruxolitinib (5 to 25 mg BID).	TG10 + TG20: Daily/Weekly Dosing n=16 Participants Participants received at least 6 months of prior ruxolitinib therapy, including ruxolitinib administration at a stable dose of 5 mg BID to 25 mg BID for at least 8 weeks before randomization. From Day 1 to the end of Week 8, participants in TG10 and TG20 received oral parsaclisib 10 mg or 20 mg QD, respectively, followed by the same dose weekly until discontinuation criteria were met, in combination with the pre-Day 1 stable dose of ruxolitinib (5 to 25 mg BID).	Ruxolitinib 20 mg Throughout the study, participants received a stable dose of ruxolitinib 20 mg BID.	Ruxolitinib 25 mg Throughout the study, participants received a stable dose of ruxolitinib 25 mg BID.
Percent Change From Baseline in the TSS Through Week 24 as Measured by MFSAF v3.0 Symptom Diary	-29.2 percent change Standard Deviation 41.08	-16.7 percent change Standard Deviation 76.27	11.1 percent change Standard Deviation 80.23	—	—

SECONDARY outcome

Timeframe: Baseline; Week 12

The MPN-SAF weekly total score is defined as the sum of 10 individual symptom scores (fatigue, nights sweats, itchiness, bone pain, fever, unintentional weight loss last 6 months, early satiety, abdominal discomfort, inactivity, problems with concentration) collected at the same visit using an 11-point scale. Participants scored each symptom using a scale from 0 (absent) to 10 (worst imaginable). The TSS was calculated as a sum of all 10 symptom scores; scores ranged from 0 to 100, with higher scores corresponding to more severe symptoms. Change from Baseline was calculated as the post-Baseline score minus the Baseline score.

Outcome measures

Outcome measures
Measure	TG5I/M n=18 Participants Participants received at least 6 months of prior ruxolitinib therapy, including ruxolitinib administration at a stable dose of 5 milligrams (mg) twice a day (BID) to 25 mg BID for at least 8 weeks before randomization. From Day 1 to the end of Week 8, participants received oral parsaclisib 20 mg once daily (QD), followed by 5 mg QD until discontinuation criteria were met, in combination with the pre-Day 1 stable dose of ruxolitinib (5 to 25 mg BID).	TG5D n=19 Participants Participants received at least 6 months of prior ruxolitinib therapy, including ruxolitinib administration at a stable dose of 5 mg BID to 25 mg BID for at least 8 weeks before randomization. From Day 1, participants received oral parsaclisib 5 mg QD until discontinuation criteria were met, in combination with the pre-Day 1 stable dose of ruxolitinib (5 to 25 mg BID).	TG10 + TG20: Daily/Weekly Dosing n=28 Participants Participants received at least 6 months of prior ruxolitinib therapy, including ruxolitinib administration at a stable dose of 5 mg BID to 25 mg BID for at least 8 weeks before randomization. From Day 1 to the end of Week 8, participants in TG10 and TG20 received oral parsaclisib 10 mg or 20 mg QD, respectively, followed by the same dose weekly until discontinuation criteria were met, in combination with the pre-Day 1 stable dose of ruxolitinib (5 to 25 mg BID).	Ruxolitinib 20 mg Throughout the study, participants received a stable dose of ruxolitinib 20 mg BID.	Ruxolitinib 25 mg Throughout the study, participants received a stable dose of ruxolitinib 25 mg BID.
Change From Baseline in the TSS Through Week 12 as Measured by Myeloproliferative Neoplasm Symptom Assessment Form (MPN-SAF) Baseline	30.0 scores on a scale Standard Deviation 17.88	27.7 scores on a scale Standard Deviation 18.18	29.2 scores on a scale Standard Deviation 19.56	—	—
Change From Baseline in the TSS Through Week 12 as Measured by Myeloproliferative Neoplasm Symptom Assessment Form (MPN-SAF) Change from Baseline at Week 12	-10.6 scores on a scale Standard Deviation 12.63	-12.6 scores on a scale Standard Deviation 15.52	-4.8 scores on a scale Standard Deviation 9.78	—	—

SECONDARY outcome

Timeframe: Baseline; Week 12

The MPN-SAF weekly total score is defined as the sum of 10 individual symptom scores (fatigue, nights sweats, itchiness, bone pain, fever, unintentional weight loss last 6 months, early satiety, abdominal discomfort, inactivity, problems with concentration) collected at the same visit using an 11-point scale. Participants scored each symptom using a scale from 0 (absent) to 10 (worst imaginable). The TSS was calculated as a sum of all 10 symptom scores; scores ranged from 0 to 100, with higher scores corresponding to more severe symptoms. Percent change from Baseline was calculated as the (\[post-Baseline value minus the Baseline value\] / Baseline value) x 100.

Outcome measures

Outcome measures
Measure	TG5I/M n=14 Participants Participants received at least 6 months of prior ruxolitinib therapy, including ruxolitinib administration at a stable dose of 5 milligrams (mg) twice a day (BID) to 25 mg BID for at least 8 weeks before randomization. From Day 1 to the end of Week 8, participants received oral parsaclisib 20 mg once daily (QD), followed by 5 mg QD until discontinuation criteria were met, in combination with the pre-Day 1 stable dose of ruxolitinib (5 to 25 mg BID).	TG5D n=16 Participants Participants received at least 6 months of prior ruxolitinib therapy, including ruxolitinib administration at a stable dose of 5 mg BID to 25 mg BID for at least 8 weeks before randomization. From Day 1, participants received oral parsaclisib 5 mg QD until discontinuation criteria were met, in combination with the pre-Day 1 stable dose of ruxolitinib (5 to 25 mg BID).	TG10 + TG20: Daily/Weekly Dosing n=20 Participants Participants received at least 6 months of prior ruxolitinib therapy, including ruxolitinib administration at a stable dose of 5 mg BID to 25 mg BID for at least 8 weeks before randomization. From Day 1 to the end of Week 8, participants in TG10 and TG20 received oral parsaclisib 10 mg or 20 mg QD, respectively, followed by the same dose weekly until discontinuation criteria were met, in combination with the pre-Day 1 stable dose of ruxolitinib (5 to 25 mg BID).	Ruxolitinib 20 mg Throughout the study, participants received a stable dose of ruxolitinib 20 mg BID.	Ruxolitinib 25 mg Throughout the study, participants received a stable dose of ruxolitinib 25 mg BID.
Percent Change From Baseline in the TSS Through Week 12 as Measured by MPN-SAF	-28.7 percent change Standard Deviation 42.48	-38.1 percent change Standard Deviation 44.76	-20.1 percent change Standard Deviation 40.88	—	—

SECONDARY outcome

Timeframe: Baseline; Week 24

Outcome measures

Outcome measures
Measure	TG5I/M n=18 Participants Participants received at least 6 months of prior ruxolitinib therapy, including ruxolitinib administration at a stable dose of 5 milligrams (mg) twice a day (BID) to 25 mg BID for at least 8 weeks before randomization. From Day 1 to the end of Week 8, participants received oral parsaclisib 20 mg once daily (QD), followed by 5 mg QD until discontinuation criteria were met, in combination with the pre-Day 1 stable dose of ruxolitinib (5 to 25 mg BID).	TG5D n=19 Participants Participants received at least 6 months of prior ruxolitinib therapy, including ruxolitinib administration at a stable dose of 5 mg BID to 25 mg BID for at least 8 weeks before randomization. From Day 1, participants received oral parsaclisib 5 mg QD until discontinuation criteria were met, in combination with the pre-Day 1 stable dose of ruxolitinib (5 to 25 mg BID).	TG10 + TG20: Daily/Weekly Dosing n=28 Participants Participants received at least 6 months of prior ruxolitinib therapy, including ruxolitinib administration at a stable dose of 5 mg BID to 25 mg BID for at least 8 weeks before randomization. From Day 1 to the end of Week 8, participants in TG10 and TG20 received oral parsaclisib 10 mg or 20 mg QD, respectively, followed by the same dose weekly until discontinuation criteria were met, in combination with the pre-Day 1 stable dose of ruxolitinib (5 to 25 mg BID).	Ruxolitinib 20 mg Throughout the study, participants received a stable dose of ruxolitinib 20 mg BID.	Ruxolitinib 25 mg Throughout the study, participants received a stable dose of ruxolitinib 25 mg BID.
Change From Baseline in the TSS Through Week 24 as Measured by MPN-SAF Baseline	30.0 scores on a scale Standard Deviation 17.88	27.7 scores on a scale Standard Deviation 18.18	29.2 scores on a scale Standard Deviation 19.56	—	—
Change From Baseline in the TSS Through Week 24 as Measured by MPN-SAF Change from Baseline at Week 24	-15.6 scores on a scale Standard Deviation 9.95	-12.6 scores on a scale Standard Deviation 16.46	-10.3 scores on a scale Standard Deviation 11.88	—	—

SECONDARY outcome

Timeframe: Baseline; Week 24

The MPN-SAF weekly total score is defined as the sum of 10 individual symptom scores (fatigue, nights sweats, itchiness, bone pain, fever, unintentional weight loss last 6 months, early satiety, abdominal discomfort, inactivity, problems with concentration) collected at the same visit using an 11-point scale. Participants scored each symptom using a scale from 0 (absent) to 10 (worst imaginable). The TSS was calculated as a sum of all 10 symptom scores; scores ranged from 0 to 100, with higher scores corresponding to more severe symptoms. Percent change from Baseline was calculated as the (\[post-Baseline value minus the Baseline value\] / Baseline value) x 100.

Outcome measures

Outcome measures
Measure	TG5I/M n=13 Participants Participants received at least 6 months of prior ruxolitinib therapy, including ruxolitinib administration at a stable dose of 5 milligrams (mg) twice a day (BID) to 25 mg BID for at least 8 weeks before randomization. From Day 1 to the end of Week 8, participants received oral parsaclisib 20 mg once daily (QD), followed by 5 mg QD until discontinuation criteria were met, in combination with the pre-Day 1 stable dose of ruxolitinib (5 to 25 mg BID).	TG5D n=13 Participants Participants received at least 6 months of prior ruxolitinib therapy, including ruxolitinib administration at a stable dose of 5 mg BID to 25 mg BID for at least 8 weeks before randomization. From Day 1, participants received oral parsaclisib 5 mg QD until discontinuation criteria were met, in combination with the pre-Day 1 stable dose of ruxolitinib (5 to 25 mg BID).	TG10 + TG20: Daily/Weekly Dosing n=15 Participants Participants received at least 6 months of prior ruxolitinib therapy, including ruxolitinib administration at a stable dose of 5 mg BID to 25 mg BID for at least 8 weeks before randomization. From Day 1 to the end of Week 8, participants in TG10 and TG20 received oral parsaclisib 10 mg or 20 mg QD, respectively, followed by the same dose weekly until discontinuation criteria were met, in combination with the pre-Day 1 stable dose of ruxolitinib (5 to 25 mg BID).	Ruxolitinib 20 mg Throughout the study, participants received a stable dose of ruxolitinib 20 mg BID.	Ruxolitinib 25 mg Throughout the study, participants received a stable dose of ruxolitinib 25 mg BID.
Percent Change From Baseline in the TSS Through Week 24 as Measured by MPN-SAF	-63.4 percent change Standard Deviation 28.14	-44.7 percent change Standard Deviation 38.07	-35.9 percent change Standard Deviation 40.43	—	—

SECONDARY outcome

Timeframe: Baseline; up to 1494 days (EOT)

Population: Initial Safety Population. Analysis was conducted on the Safety Population during the initial safety period. Due to early termination of the study, per the Statistical Analysis Plan, daily and weekly dosing arms were combined for efficacy analysis.

The PGIC questionnaire consists of a single question with 7 possible answers: "Since the start of treatment you've received in this study, your myelofibrosis symptoms are: 1, very much improved; 2, much improved; 3, minimally improved; 4, no change; 5, minimally worse; 6, much worse; 7, very much worse."

Outcome measures

Outcome measures
Measure	TG5I/M n=21 Participants Participants received at least 6 months of prior ruxolitinib therapy, including ruxolitinib administration at a stable dose of 5 milligrams (mg) twice a day (BID) to 25 mg BID for at least 8 weeks before randomization. From Day 1 to the end of Week 8, participants received oral parsaclisib 20 mg once daily (QD), followed by 5 mg QD until discontinuation criteria were met, in combination with the pre-Day 1 stable dose of ruxolitinib (5 to 25 mg BID).	TG5D n=21 Participants Participants received at least 6 months of prior ruxolitinib therapy, including ruxolitinib administration at a stable dose of 5 mg BID to 25 mg BID for at least 8 weeks before randomization. From Day 1, participants received oral parsaclisib 5 mg QD until discontinuation criteria were met, in combination with the pre-Day 1 stable dose of ruxolitinib (5 to 25 mg BID).	TG10 + TG20: Daily/Weekly Dosing n=32 Participants Participants received at least 6 months of prior ruxolitinib therapy, including ruxolitinib administration at a stable dose of 5 mg BID to 25 mg BID for at least 8 weeks before randomization. From Day 1 to the end of Week 8, participants in TG10 and TG20 received oral parsaclisib 10 mg or 20 mg QD, respectively, followed by the same dose weekly until discontinuation criteria were met, in combination with the pre-Day 1 stable dose of ruxolitinib (5 to 25 mg BID).	Ruxolitinib 20 mg Throughout the study, participants received a stable dose of ruxolitinib 20 mg BID.	Ruxolitinib 25 mg Throughout the study, participants received a stable dose of ruxolitinib 25 mg BID.
Number of Participants With the Indicated Patient Global Impression of Change (PGIC) Score at Week 12, Week 24, and the End of Treatment (EOT) EOT, very much worse	0 Participants	0 Participants	1 Participants	—	—
Number of Participants With the Indicated Patient Global Impression of Change (PGIC) Score at Week 12, Week 24, and the End of Treatment (EOT) Week 12, minimally worse	2 Participants	0 Participants	3 Participants	—	—
Number of Participants With the Indicated Patient Global Impression of Change (PGIC) Score at Week 12, Week 24, and the End of Treatment (EOT) Week 12, much worse	0 Participants	0 Participants	1 Participants	—	—
Number of Participants With the Indicated Patient Global Impression of Change (PGIC) Score at Week 12, Week 24, and the End of Treatment (EOT) Week 12, very much improved	1 Participants	1 Participants	1 Participants	—	—
Number of Participants With the Indicated Patient Global Impression of Change (PGIC) Score at Week 12, Week 24, and the End of Treatment (EOT) Week 12, much improved	4 Participants	4 Participants	8 Participants	—	—
Number of Participants With the Indicated Patient Global Impression of Change (PGIC) Score at Week 12, Week 24, and the End of Treatment (EOT) Week 12, minimally improved	5 Participants	6 Participants	5 Participants	—	—
Number of Participants With the Indicated Patient Global Impression of Change (PGIC) Score at Week 12, Week 24, and the End of Treatment (EOT) Week 12, very much worse	0 Participants	0 Participants	0 Participants	—	—
Number of Participants With the Indicated Patient Global Impression of Change (PGIC) Score at Week 12, Week 24, and the End of Treatment (EOT) Week 12, no change	6 Participants	6 Participants	6 Participants	—	—
Number of Participants With the Indicated Patient Global Impression of Change (PGIC) Score at Week 12, Week 24, and the End of Treatment (EOT) Week 12, not reported	3 Participants	4 Participants	8 Participants	—	—
Number of Participants With the Indicated Patient Global Impression of Change (PGIC) Score at Week 12, Week 24, and the End of Treatment (EOT) Week 24, very much improved	1 Participants	1 Participants	3 Participants	—	—
Number of Participants With the Indicated Patient Global Impression of Change (PGIC) Score at Week 12, Week 24, and the End of Treatment (EOT) Week 24, much improved	7 Participants	4 Participants	9 Participants	—	—
Number of Participants With the Indicated Patient Global Impression of Change (PGIC) Score at Week 12, Week 24, and the End of Treatment (EOT) Week 24, minimally improved	4 Participants	6 Participants	4 Participants	—	—
Number of Participants With the Indicated Patient Global Impression of Change (PGIC) Score at Week 12, Week 24, and the End of Treatment (EOT) Week 24, no change	3 Participants	1 Participants	3 Participants	—	—
Number of Participants With the Indicated Patient Global Impression of Change (PGIC) Score at Week 12, Week 24, and the End of Treatment (EOT) Week 24, minimally worse	0 Participants	1 Participants	0 Participants	—	—
Number of Participants With the Indicated Patient Global Impression of Change (PGIC) Score at Week 12, Week 24, and the End of Treatment (EOT) Week 24, much worse	0 Participants	0 Participants	0 Participants	—	—
Number of Participants With the Indicated Patient Global Impression of Change (PGIC) Score at Week 12, Week 24, and the End of Treatment (EOT) Week 24, very much worse	0 Participants	0 Participants	0 Participants	—	—
Number of Participants With the Indicated Patient Global Impression of Change (PGIC) Score at Week 12, Week 24, and the End of Treatment (EOT) Week 24, not reported	6 Participants	8 Participants	13 Participants	—	—
Number of Participants With the Indicated Patient Global Impression of Change (PGIC) Score at Week 12, Week 24, and the End of Treatment (EOT) EOT, very much improved	0 Participants	0 Participants	1 Participants	—	—
Number of Participants With the Indicated Patient Global Impression of Change (PGIC) Score at Week 12, Week 24, and the End of Treatment (EOT) EOT, much improved	2 Participants	6 Participants	4 Participants	—	—
Number of Participants With the Indicated Patient Global Impression of Change (PGIC) Score at Week 12, Week 24, and the End of Treatment (EOT) EOT, minimally improved	7 Participants	3 Participants	1 Participants	—	—
Number of Participants With the Indicated Patient Global Impression of Change (PGIC) Score at Week 12, Week 24, and the End of Treatment (EOT) EOT, no change	4 Participants	5 Participants	3 Participants	—	—
Number of Participants With the Indicated Patient Global Impression of Change (PGIC) Score at Week 12, Week 24, and the End of Treatment (EOT) EOT, minimally worse	2 Participants	1 Participants	2 Participants	—	—
Number of Participants With the Indicated Patient Global Impression of Change (PGIC) Score at Week 12, Week 24, and the End of Treatment (EOT) EOT, much worse	1 Participants	1 Participants	2 Participants	—	—
Number of Participants With the Indicated Patient Global Impression of Change (PGIC) Score at Week 12, Week 24, and the End of Treatment (EOT) EOT, not reported	5 Participants	5 Participants	18 Participants	—	—

SECONDARY outcome

Timeframe: up to 1494 days (EOT)

Outcome measures

Outcome measures
Measure	TG5I/M n=21 Participants Participants received at least 6 months of prior ruxolitinib therapy, including ruxolitinib administration at a stable dose of 5 milligrams (mg) twice a day (BID) to 25 mg BID for at least 8 weeks before randomization. From Day 1 to the end of Week 8, participants received oral parsaclisib 20 mg once daily (QD), followed by 5 mg QD until discontinuation criteria were met, in combination with the pre-Day 1 stable dose of ruxolitinib (5 to 25 mg BID).	TG5D n=21 Participants Participants received at least 6 months of prior ruxolitinib therapy, including ruxolitinib administration at a stable dose of 5 mg BID to 25 mg BID for at least 8 weeks before randomization. From Day 1, participants received oral parsaclisib 5 mg QD until discontinuation criteria were met, in combination with the pre-Day 1 stable dose of ruxolitinib (5 to 25 mg BID).	TG10 + TG20: Daily/Weekly Dosing n=32 Participants Participants received at least 6 months of prior ruxolitinib therapy, including ruxolitinib administration at a stable dose of 5 mg BID to 25 mg BID for at least 8 weeks before randomization. From Day 1 to the end of Week 8, participants in TG10 and TG20 received oral parsaclisib 10 mg or 20 mg QD, respectively, followed by the same dose weekly until discontinuation criteria were met, in combination with the pre-Day 1 stable dose of ruxolitinib (5 to 25 mg BID).	Ruxolitinib 20 mg Throughout the study, participants received a stable dose of ruxolitinib 20 mg BID.	Ruxolitinib 25 mg Throughout the study, participants received a stable dose of ruxolitinib 25 mg BID.
Mean PGIC Score at Week 12, Week 24, and the EOT Week 12	3.2 scores on a scale Standard Deviation 1.11	3.0 scores on a scale Standard Deviation 0.94	3.2 scores on a scale Standard Deviation 1.28	—	—
Mean PGIC Score at Week 12, Week 24, and the EOT Week 24	2.6 scores on a scale Standard Deviation 0.91	2.8 scores on a scale Standard Deviation 1.01	2.4 scores on a scale Standard Deviation 0.96	—	—
Mean PGIC Score at Week 12, Week 24, and the EOT EOT	3.6 scores on a scale Standard Deviation 1.09	3.3 scores on a scale Standard Deviation 1.24	3.8 scores on a scale Standard Deviation 1.85	—	—

SECONDARY outcome

Timeframe: Week 12 and every 12 weeks thereafter (up to 1494 days [EOT])

A participant was considered as a responder if the participant had a best overall response of CR or PR. CR: (a) bone marrow (BM): age-adjusted normocellularity (AAN); \< 5% blasts; ≤ grade 1 myelofibrosis (MF); (b) peripheral blood (PD): hemoglobin (Hg) ≥ 100 grams per Liter (g/L) and \< upper normal limit (UNL); neutrophils ≥ 1 × 10\^9/L and \< UNL; (c) platelets ≥ 100 × 10\^9/L and \< UNL; \< 2% immature myeloid cells (IMCs); (d) clinical: resolution of disease symptoms; spleen/liver not palpable; no extramedullary hematopoiesis (EMH). PR: (a) PB: Hg ≥ 100 g/L and \< UNL; neutrophils ≥ 1 × 10\^9/L and \< UNL; platelets ≥ 100 × 10\^9/L and \< UNL; \< 2% IMCs; (b) clinical: resolution of disease symptoms; spleen/liver not palpable; no EMH; (c) BM: AAN; \< 5% blasts; ≤ Grade 1 MF; and PB: Hg ≥ 85 g/L but \< 100 g/L and \< UNL; neutrophils ≥ 1 × 10\^9/L and \< UNL; platelets ≥ 50 × 10\^9/L but \< 100 × 10\^9/L and \< UNL; \< 2% IMCs.

Outcome measures

Outcome measures
Measure	TG5I/M n=21 Participants Participants received at least 6 months of prior ruxolitinib therapy, including ruxolitinib administration at a stable dose of 5 milligrams (mg) twice a day (BID) to 25 mg BID for at least 8 weeks before randomization. From Day 1 to the end of Week 8, participants received oral parsaclisib 20 mg once daily (QD), followed by 5 mg QD until discontinuation criteria were met, in combination with the pre-Day 1 stable dose of ruxolitinib (5 to 25 mg BID).	TG5D n=21 Participants Participants received at least 6 months of prior ruxolitinib therapy, including ruxolitinib administration at a stable dose of 5 mg BID to 25 mg BID for at least 8 weeks before randomization. From Day 1, participants received oral parsaclisib 5 mg QD until discontinuation criteria were met, in combination with the pre-Day 1 stable dose of ruxolitinib (5 to 25 mg BID).	TG10 + TG20: Daily/Weekly Dosing n=32 Participants Participants received at least 6 months of prior ruxolitinib therapy, including ruxolitinib administration at a stable dose of 5 mg BID to 25 mg BID for at least 8 weeks before randomization. From Day 1 to the end of Week 8, participants in TG10 and TG20 received oral parsaclisib 10 mg or 20 mg QD, respectively, followed by the same dose weekly until discontinuation criteria were met, in combination with the pre-Day 1 stable dose of ruxolitinib (5 to 25 mg BID).	Ruxolitinib 20 mg Throughout the study, participants received a stable dose of ruxolitinib 20 mg BID.	Ruxolitinib 25 mg Throughout the study, participants received a stable dose of ruxolitinib 25 mg BID.
Best Overall Response (Percentage of Participants With Complete Response [CR] or Partial Response [PR]) for Investigator-Reported International Working Group-Myeloproliferative Neoplasms Research and Treatment (IWG-MRT) Response Assessment	0.0 percentage of participants	9.5 percentage of participants	9.4 percentage of participants	—	—

SECONDARY outcome

Timeframe: up to approximately 4 years

An adverse event (AE) was defined as any untoward medical occurrence associated with the use of a drug in humans, whether or not considered drug related, that occurred after a participant provided informed consent. Abnormal laboratory values or test results occurring after informed consent constituted AEs only if they induced clinical signs or symptoms, were considered clinically meaningful, required therapy (e.g., hematologic abnormality that required transfusion), or requird changes in the study drug(s). TEAEs were defined as AEs that began or worsened from Baseline after the first administration of study drug.

Outcome measures

Outcome measures
Measure	TG5I/M n=21 Participants Participants received at least 6 months of prior ruxolitinib therapy, including ruxolitinib administration at a stable dose of 5 milligrams (mg) twice a day (BID) to 25 mg BID for at least 8 weeks before randomization. From Day 1 to the end of Week 8, participants received oral parsaclisib 20 mg once daily (QD), followed by 5 mg QD until discontinuation criteria were met, in combination with the pre-Day 1 stable dose of ruxolitinib (5 to 25 mg BID).	TG5D n=21 Participants Participants received at least 6 months of prior ruxolitinib therapy, including ruxolitinib administration at a stable dose of 5 mg BID to 25 mg BID for at least 8 weeks before randomization. From Day 1, participants received oral parsaclisib 5 mg QD until discontinuation criteria were met, in combination with the pre-Day 1 stable dose of ruxolitinib (5 to 25 mg BID).	TG10 + TG20: Daily/Weekly Dosing n=32 Participants Participants received at least 6 months of prior ruxolitinib therapy, including ruxolitinib administration at a stable dose of 5 mg BID to 25 mg BID for at least 8 weeks before randomization. From Day 1 to the end of Week 8, participants in TG10 and TG20 received oral parsaclisib 10 mg or 20 mg QD, respectively, followed by the same dose weekly until discontinuation criteria were met, in combination with the pre-Day 1 stable dose of ruxolitinib (5 to 25 mg BID).	Ruxolitinib 20 mg Throughout the study, participants received a stable dose of ruxolitinib 20 mg BID.	Ruxolitinib 25 mg Throughout the study, participants received a stable dose of ruxolitinib 25 mg BID.
Number of Participants With Any Treatment-emergent Adverse Event (TEAE)	20 Participants	20 Participants	31 Participants	—	—

SECONDARY outcome

Timeframe: up to approximately 4 years

Population: Transition Safety Population. AEs were reported in the initial randomization group (TG10, TG20) if the start of the AEs occurred before transitioning to TG5D. If the start of the AEs occurred after transitioning to TG5D, they were reported in the TG5D Transition arm.

An AE was defined as any untoward medical occurrence associated with the use of a drug in humans, whether or not considered drug related, that occurred after a participant provided informed consent. Abnormal laboratory values or test results occurring after informed consent constituted AEs only if they induced clinical signs or symptoms, were considered clinically meaningful, required therapy (e.g., hematologic abnormality that required transfusion), or requird changes in the study drug(s). TEAEs were defined as AEs that began or worsened from Baseline after the first administration of study drug. Participants who had been assigned to dosing arms with weekly dosing beyond Week 8 had the opportunity to transition to all daily dosing at 5 mg if agreed upon by the participant and the Investigator.