A Phase 1, Open-Label, Safety and Tolerability Study of INCB057643 in Participants With Myelofibrosis and Other Advanced Myeloid Neoplasms LIMBER

What's the purpose of this trial?

The purpose of this study is to evaluate the safety, tolerability, and preliminary efficacy of INCB057643 as monotherapy or combination with ruxolitinib for participants with myelofibrosis and other myeloid neoplasms.

This trial is currently open and accepting patients.

What will happen during the trial?

You may be able to join this trial if you:

The following criteria is a partial list of reasons why patients may be eligible to participate in this clinical trial. Further evaluation with a medical professional is required.

Inclusion Criteria:

* Age 18 years and older at the time of signing the informed consent.
* Part 1: Relapsed or refractory MF, MDS, or MDS/MPN

a. Disease type:

* Primary MF or secondary MFs (post-PV MF, post-ET MF), histologically or cytologically confirmed according to WHO 2016 criteria with measurable disease and risk category of intermediate-2 or high according to DIPSS.
* Measurable disease is defined:

For dose escalation as having a palpable spleen of ≥ 5 cm below the left subcostal margin (ribs).


* Very low-, low-, intermediate-, or high risk MDS as per the IPSS-R criteria

* Low-, intermediate-, or high-risk chronic myelomonocytic leukemia, atypical chronic myeloid leukemia, MDS/MPN with ring sideroblasts and thrombocytosis, and MDS/MPN unclassifiable as per the WHO 2016 criteria.
* Exception: Participants presenting with juvenile myelomonocytic leukemia will be excluded.

b. Prior therapy
* Received at least 1 line of prior therapy; is refractory, relapsed, or intolerant to the last therapy; and there is no further available therapy known to provide clinical benefits, in the opinion of the investigator.
* Participants with MF must have received a JAK inhibitor(s) such as ruxolitinib.
* Part 2: MF - dose escalation and expansion

a. Disease type
* Primary MF or secondary MFs (post-PV MF, post-ET MF), histologically or cytologically confirmed according to WHO 2016 criteria.
* Measurable disease is defined as having a palpable spleen of \> 10 cm below the left subcostal margin.
* 2 subgroups of participants in Part 2 - dose expansion will be enrolled:
* bone marrow myeloblast percentage between 5% (≥ 5%) and less than 20% (\< 20%) or myeloblast percentage ≥ 10% in peripheral blood in 2 occasions at least 2 weeks apart.

b. Prior therapy
* Must currently be treated with ruxolitinib monotherapy at a stable dose for ≥ 8 weeks immediately preceding the first dose of study treatment.
* Must not be a candidate for potentially curative therapy, including hematopoietic stem-cell transplantation.
* Willingness to undergo a pretreatment bone marrow biopsy and/or aspirate at screening/baseline, or archival sample obtained since completion of most recent therapy.
* Willingness to avoid pregnancy or fathering children based on the criteria below.

Exclusion Criteria:

* Prior receipt of a BET inhibitor within 5 half-lives of the compound, and/or experienced BET inhibitor-related AE(s) resulting in dose discontinuation.

Note: For participants in Part 2, ruxolitinib will continue at the participants' current, ongoing doses. No ruxolitinib washout is needed.

* Concurrent anticancer therapy
* Participants who have received allogeneic hematopoietic stem cell transplantation within 6 months of enrollment
* Active HBV or HCV infection or at risk for HBV reactivation.

Additional Trial Information

Phase 1

Enrollment: 138 patients (estimated)

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Trial Locations

All Trial Locations

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University of Alabama at Birmingham O'Neal Comprehensive Cancer Center at UAB

Birmingham, AL

Open and Accepting


University of Colorado Cancer Center Anschutz Cancer Pavilion

Aurora, CO

Open and Accepting



Winship Cancer Institute of Emory University (Main Campus)

Atlanta, GA

Open and Accepting

North Carolina

UNC Lineberger Comprehensive Cancer Center University of North Carolina

Chapel Hill, NC

Open and Accepting


MD Anderson Cancer Center The University of Texas

Houston, TX

Open and Accepting


Huntsman Cancer Institute University of Utah

Salt Lake City, UT

Open and Accepting


Seattle Cancer Care Alliance SCCA

Seattle, WA

Open and Accepting
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