Phase 3 Study of Pelabresib (CPI-0610) in Myelofibrosis (MF) (MANIFEST-2)

Splenic response was characterized by a reduction of at least 35% in spleen volume from baseline (SVR35), as determined by magnetic resonance imaging (MRI) or computerized tomography (CT), and evaluated through a blinded central radiology review at Week 24.

The Total Symptom Score (TSS) at Week 24, compared to baseline, was measured using the Myelofibrosis Symptom Assessment Form v4.0. This score represented the sum of seven individual symptom items, each rated on a 0-10 scale, resulting in a possible total daily score ranging from 0 to 70. A higher TSS reflected a greater disease burden and therefore a worse outcome. The baseline TSS was calculated as the average of non-missing daily total symptom scores over the seven-day period preceding the day of randomization. The TSS for each treatment week was determined as the average of non-missing daily total symptom scores for that week. However, if fewer than four daily scores were available for a given week, the weekly TSS was considered missing.

The probability of a TSS response at Week 24 was estimated by calculating the TSS response rate, defined as the percentage of patients who achieved a TSS50 response at Week 24 in each of the two treatment groups. The Total Symptom Score (TSS) response was defined as a ≥50% reduction from baseline in TSS, as measured by the Myelofibrosis Symptom Assessment Form v4.0.

Percent Change From Baseline in Total Symptom Score (TSS) at Week 24 measured the change in a patient's symptoms after 24 weeks of treatment, relative to baseline. A negative value indicates symptom improvement, and a reduction of ≥50% is typically considered a meaningful clinical response.

Improvement in bone marrow fibrosis by at least 1 grade, as assessed by central read compared to baseline, was analyzed by treatment group and overall. The improvement in bone marrow fibrosis grade was defined as a decrease by at least 1 grade in bone marrow fibrosis grade when compared to baseline, where a grade of MF-3 was the most severe, and MF-0 was the least severe.

Splenic response is characterized by a reduction of at least 35% in spleen volume from baseline (SVR35), as determined by magnetic resonance imaging (MRI) or computerized tomography (CT), and evaluated through a blinded central radiology review at Week 48.

The probability of a TSS response at Week 48 is estimated by calculating the TSS response rate, defined as the percentage of patients who achieve a TSS50 response at Week 48 in each of the two treatment groups. The Total Symptom Score (TSS) response is defined as a ≥50% reduction from baseline in TSS, as measured by the Myelofibrosis Symptom Assessment Form v4.0.

The Total Symptom Score (TSS) at Week 48, compared to baseline, is measured using the Myelofibrosis Symptom Assessment Form v4.0. This score represents the sum of seven individual symptom items, each rated on a 0-10 scale, resulting in a possible total daily score ranging from 0 to 70. A higher TSS reflects a greater disease burden and therefore a worse outcome. The baseline TSS is calculated as the average of non-missing daily total symptom scores over the seven-day period preceding the day of randomization. The TSS for each treatment week is determined as the average of non-missing daily total symptom scores for that week. However, if fewer than four daily scores are available for a given week, the weekly TSS is considered missing.

The rate of RBC transfusions was defined as the average number of RBC units transfused per patient month (4 weeks) during the first 24 weeks of treatment. The average number of RBC units per patient-month was calculated by dividing the total (ie, for all patients) number of RBC units in the whole exposure time by the sum of patient-months.

Transfusion dependence (TD) was defined as having received ≥6 units of RBCs during the 12-week baseline period prior to dosing and Transfusion independence (TI) was defined as the absence of RBC transfusions during any continuous 12-week period of the double-blind treatment phase.

The conversion from TD to TI was evaluated and defined as the proportion of patients who transitioned from transfusion dependence to transfusion independence. Patients who remained in the double-blind treatment period and had not received any RBC transfusions during the most recent 12 weeks were considered responders. Patients who discontinued from the double-blind treatment before Week 12 were classified as non-responders.

The Patient Global Impression of Change (PGIC) was a single-item measure of the patient's perceived change in MF symptoms since starting treatment. Patients responded to: "Since beginning this study treatment, your myelofibrosis symptoms were: (1) Very much improved, (2) Much improved, (3) Minimally improved, (4) No change, (5) Minimally worse, (6) Much worse, (7) Very much worse."

Progression-Free Survival (PFS), defined as the time from randomization until documented progression, or until death from any cause for patients without documented progression

OS, defined as the time from randomization until death from any cause

Patients are categorized as having transformed to Acute Myelogenous Leukemia (AML) when the peripheral blood blast percentage increases to ≥20% and this elevation persists for at least two weeks, or when leukemic transformation is confirmed through disease status assessment.

A treatment-emergent adverse event (TEAE) for the double-blind treatment period is defined as an AE that has a start date on or after the first dose of the pelabresib/placebo and before 30 days after the last dose of pelabresib/placebo or before the start of alternative (off-study) treatment for MF, whichever occurs first. If the AE has a start date before the date of first dose but increases in severity after first dose and before 30 days post last dose will be considered a TEAE as well. An AE that occurs after the administration of the first dose of open-label pelabresib treatment will be considered treatment-emergent for the crossover treatment period. However, a TEAE for the crossover treatment period that occurs within 30 days after the last dose of pelabresib/placebo will be considered treatment emergent for the double-blind treatment period as well.

Pharmacokinetic (PK) parameters will be calculated based on Pelabresib plasma concentrations and actual sampling time points.

AUC0-t will be listed and summarized using descriptive statistics.

Pharmacokinetic (PK) parameters will be calculated based on Pelabresib plasma concentrations and actual sampling time points.

AUC0-t will be listed and summarized using descriptive statistics. Tmax will be listed and summarized using descriptive statistics.

Pharmacokinetic (PK) parameters will be calculated based on Pelabresib plasma concentrations and actual sampling time points.

AUC0-t will be listed and summarized using descriptive statistics. Cmax will be listed and summarized using descriptive statistics.

Pharmacokinetic (PK) parameters will be calculated based on Pelabresib plasma concentrations and actual sampling time points.

T1/2 will be listed and summarized using descriptive statistics.

Pharmacokinetic (PK) parameters will be calculated based on Pelabresib plasma concentrations and actual sampling time points.

Vd/F will be listed and summarized using descriptive statistics.

Pharmacokinetic (PK) parameters will be calculated based on Pelabresib plasma concentrations and actual sampling time points.

CL/F will be listed and summarized using descriptive statistics.

Blood samples (approximately 4 mL each) will be collected at the time points specified in the Schedule of Assessments (SOA) to determine plasma concentrations of Ruxolitinib plasma concentrations in the presence or absence of Pelabresib

Duration of splenic response, defined as the time from onset of splenic response until the time at which the patient has a <35% decrease from baseline in spleen volume and a >25% increase from nadir, as confirmed by the central review) or death, whichever comes first

The modified TSS (mTSS) was defined as TSS without the fatigue sub-domain and with a total scale of 60 points versus 70 points for TSS. Patients were classified as responders if the percentage of change from baseline in mTSS was ≤ -50% at Week 24.

Duration of TSS response, defined as the time from onset of TSS50 response until the time at which the patient has a <50% reduction in TSS from baseline and an increase of ≥25% from nadir