To Evaluate Efficacy and Safety of Parsaclisib and Ruxolitinib in Participants With Myelofibrosis Who Have Suboptimal Response to Ruxolitinib (LIMBER-304)
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ClinicalTrials.gov Identifier: NCT04551053 |
Recruitment Status :
Active, not recruiting
First Posted : September 16, 2020
Last Update Posted : March 15, 2023
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Condition or disease | Intervention/treatment | Phase |
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Myelofibrosis Primary Myelofibrosis Post Essential Thrombocythemia Myelofibrosis Post Polycythemia Vera Myelofibrosis | Drug: parsaclisib Drug: ruxolitinib Drug: placebo | Phase 3 |
Prospective participants must be on stable doses of ruxolitinib ranging from 5 mg BID to 25 mg BID and will have been on that dose for at least the last 8 weeks prior to Day 1. At least 3 months duration of prior ruxolitinib is required. Participants must meet Protocol-defined criteria for suboptimal response to ruxolitinib monotherapy. After participants have been determined to be eligible for the study and completed the baseline symptom diary assessment for 7 days, they will be randomized to 1 of 2 treatment groups, with stratification for platelet count (≥ 100 × 10^9/L vs 50 to < 100 × 10^9/L inclusive) and DIPSS risk category (high vs intermediate-2 vs intermediate-1).
Once a participant has completed the week 24 assessments, the participant's treatment assignment will then be unblinded and if found to be placebo, the participant will have the opportunity to crossover to begin receiving parsaclisib, together with continued ruxolitinib, as long as hematology parameters are adequate.
Study Type : | Interventional (Clinical Trial) |
Estimated Enrollment : | 212 participants |
Allocation: | Randomized |
Intervention Model: | Parallel Assignment |
Masking: | Triple (Participant, Investigator, Outcomes Assessor) |
Masking Description: | Triple blind |
Primary Purpose: | Treatment |
Official Title: | A Randomized, Double-Blind, Placebo-Controlled Study of the PI3Kδ Inhibitor Parsaclisib Plus Ruxolitinib in Participants With Myelofibrosis Who Have Suboptimal Response to Ruxolitinib |
Actual Study Start Date : | May 26, 2021 |
Estimated Primary Completion Date : | September 1, 2023 |
Estimated Study Completion Date : | June 1, 2025 |

Arm | Intervention/treatment |
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Experimental: Group A : ruxolitinib +parsaclisib
Participants will receive parsaclisib starting from Day 1 for the duration of study, while continuing to receive the stable dose of ruxolitinib they were taking for the 8 weeks prior to Day 1.
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Drug: parsaclisib
parsaclisib will be administered QD orally
Other Name: INCB050465 Drug: ruxolitinib ruxolitinib will be administered BID orally
Other Names:
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Placebo Comparator: Group B : ruxolitinib + placebo
Participants will receive placebo starting from Day 1 for the duration of study, while continuing to receive the stable dose of ruxolitinib they were taking for the 8 weeks prior to Day 1.
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Drug: ruxolitinib
ruxolitinib will be administered BID orally
Other Names:
Drug: placebo placebo will be administered QD orally |
- Proportion of participants achieving targeted reduction in spleen volume [ Time Frame: Baseline to Week 24 ]Reduction in spleen volume is measured by Magnetic Resonance Imaging (MRI) or Computed Tomography (CT).
- Proportion of participants who have a targeted reduction in Total Symptom Score (TSS) [ Time Frame: Baseline to Week 24 ]Reduction in TSS is measured by Myelofibrosis Symptom Assessment Form (MFSAF) v4.0.
- Change in TSS [ Time Frame: Baseline to Week 24 ]Change in TSS is measured by Myelofibrosis Symptom Assessment Form (MFSAF) v4.0.
- Time to the first ≥ 50% reduction in TSS [ Time Frame: Baseline to Week 24 ]Reduction in TSS is measured by Myelofibrosis Symptom Assessment Form (MFSAF) v4.0.
- Overall Survival (OS) [ Time Frame: Up to approximately 36 months ]OS is defined as randomization date to death due to any cause
- Number of Treatment Emergent Adverse Events (TEAE) [ Time Frame: Up to approximately 36 months ]Defined as any adverse event either reported for the first time or worsening of a pre-existing event after first dose of study drug up to 35 days after last dose of study drug.
- Time of onset of targeted reduction in spleen volume [ Time Frame: Baseline to Week 108 ]Reduction in spleen volume is measured by Magnetic Resonance Imaging (MRI) or Computed Tomography (CT).
- Duration of maintenance of targeted reduction in spleen volume [ Time Frame: Baseline to Week 108 ]Reduction in spleen volume is measured by Magnetic Resonance Imaging (MRI) or Computed Tomography (CT).

Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the contacts provided below. For general information, Learn About Clinical Studies.
Ages Eligible for Study: | 18 Years and older (Adult, Older Adult) |
Sexes Eligible for Study: | All |
Accepts Healthy Volunteers: | No |
Inclusion Criteria:
- Diagnosis of PMF, PPV-MF, or PET-MF.
- DIPSS risk category of intermediate-1, intermediate-2, or high.
- Treated with ruxolitinib for ≥ 3 months with a stable dose for at least the last 8 weeks prior to Day 1
- Palpable spleen of ≥ 5 cm below the left costal margin on physical examination at the screening visit.
- Active symptoms of MF at the screening visit, as demonstrated by the presence of a TSS of ≥ 10 using the Screening Symptom Form.
- Participants with an ECOG performance status score of 0, 1, or 2.
- Screening bone marrow biopsy specimen and pathology report(s) available that was obtained within the prior 2 months or willingness to undergo a bone marrow biopsy at screening/baseline; willingness to undergo bone marrow biopsy at Week 24 and every 24 weeks there after. Screening/baseline biopsy specimen must show diagnosis of MF.
- Life expectancy of at least 24 weeks.
- Willingness to avoid pregnancy or fathering children.
Exclusion Criteria:
- Prior therapy with any drug that inhibits PI3K (examples of drugs targeting this pathway include but are not limited to INCB040093, idelalisib, duvelisib, buparlisib, copanlisib, and umbralisib).
- Use of experimental drug therapy for MF or any other standard drug used for MF (whether for treatment of MF or another indication) with the exception of ruxolitinib, within 3 months of starting study drug, and/or lack of recovery from all toxicities from previous therapy (except ruxolitinib) to Grade 1 or better.
- Inability to swallow food or any condition of the upper gastrointestinal tract that precludes administration of oral medications.
- Recent history of inadequate bone marrow reserve.
- Inadequate liver and renal function at screening.
- Active bacterial, fungal, parasitic, or viral infection that requires therapy.
- Active HBV or HCV infection that requires treatment or at risk for HBV reactivation.
- Known HIV infection.
- Uncontrolled, severe, or unstable cardiac disease that in the investigator's opinion may jeopardize the safety of the participant or compliance with the Protocol.
- Active invasive malignancy over the previous 2 years.
- Splenic irradiation within 6 months before receiving the first dose of study drug.
- Concurrent use of any prohibited medications.
- Active alcohol or drug addiction that would interfere with the ability to comply with the study requirements.
- Use of any potent CYP3A4 inhibitors or inducers within 14 days or 5 half lives(whichever is longer) before the first dose of study drug or anticipated during the study.
- Inadequate recovery from toxicity and/or complications from a major surgery before starting therapy.
- Currently breastfeeding or pregnant.
- Any condition that would, in the investigator's judgment, interfere with full participation in the study, including administration of study drug and attending required study visits; pose a significant risk to the participant; or interfere with interpretation of study data.
- History of Grade 3 or 4 irAEs from prior immunotherapy.
- Receipt of any live vaccine within 30 days of the first dose of study drug
- Unwillingness to receive RBC transfusions to treat low hemoglobin levels.
- Known hypersensitivity or severe reaction to parsaclisib or ruxolitinib or excipients of parsaclisib/matching placebo or ruxolitinib formulations.

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.
Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT04551053

Study Director: | Albert Assad, M.D. | Incyte Corporation |
Responsible Party: | Incyte Corporation |
ClinicalTrials.gov Identifier: | NCT04551053 |
Obsolete Identifiers: | NCT04816565 |
Other Study ID Numbers: |
INCB 50465-304/LIMBER-304 |
First Posted: | September 16, 2020 Key Record Dates |
Last Update Posted: | March 15, 2023 |
Last Verified: | March 2023 |
Individual Participant Data (IPD) Sharing Statement: | |
Plan to Share IPD: | Yes |
Plan Description: | Incyte shares data with qualified external researchers after a research proposal is submitted. These requests are reviewed and approved by a review panel on the basis of scientific merit. All data provided is anonymized to respect the privacy of patients who have participated in the trial in line with applicable laws and regulations. The trial data availability is according to the criteria and process described on https://www.incyte.com/our-company/compliance-and-transparency |
Supporting Materials: |
Study Protocol Statistical Analysis Plan (SAP) |
Time Frame: | Data will be shared after the primary publication or 2 years after the study has ended for market authorized products and indications. |
Access Criteria: | Data from eligible studies will be shared with qualified researchers according to the criteria and process described in the Data Sharing section of the www.incyteclinicaltrials.com website. For approved requests, the researchers will be granted access to anonymized data under the terms of a data sharing agreement |
URL: | https://www.incyte.com/our-company/compliance-and-transparency |
Studies a U.S. FDA-regulated Drug Product: | Yes |
Studies a U.S. FDA-regulated Device Product: | No |
INCB050465 ruxolitinib parsaclisib LIMBER LIMBER-304 |
MF MPN Myeloproliferative Neoplasm Myelofibrosis Myoproliferative Neoplasms |
Polycythemia Vera Primary Myelofibrosis Polycythemia Thrombocytosis Thrombocythemia, Essential Myeloproliferative Disorders Bone Marrow Diseases Hematologic Diseases |
Bone Marrow Neoplasms Hematologic Neoplasms Neoplasms by Site Neoplasms Blood Platelet Disorders Blood Coagulation Disorders Hemorrhagic Disorders |