Comparing Momelotinib and Ruxolitinib in People With Untreated Myelofibrosis and Low Blood Cell Counts (APEX-MF)

A Randomized Open Label Trial Comparing Momelotinib vs Dose-Adjusted Ruxolitinib For Treatment-Naive, Cytopenic Myelofibrosis

The purpose of this study is to compare momelotinib and ruxolitinib as treatments for myelofibrosis with low blood cell counts. Both drugs are approved by the FDA to treat myelofibrosis. The study asks which drug does a better job at shrinking the spleen.

Study Overview

• Status: Not yet recruiting
• Conditions: Myelofibrosis; Myelofibrosis (MF)
• Intervention / Treatment: Drug: Momelotinib; Drug: Ruxolitinib

Detailed Description

This study is being done to answer this question:

Does momelotinib or ruxolitinib do a better job at shrinking the spleen in people who have myelofibrosis with low blood cell counts and haven't been treated yet?

Other goals of this study are to find out:

• Which drug does a better job of preventing the need for blood transfusions or other treatments
• Which drug does a better job of reducing myelofibrosis symptoms
• What side effects the drugs cause

Momelotinib and ruxolitinib are JAK inhibitors. JAK inhibitors are medicines that block a type of protein that can cause the immune system to be too active, which can cause pain and swelling (including in the spleen). JAK inhibitors are the most commonly used drugs for myelofibrosis that has caused serious symptoms including swelling in the spleen.

There are many different JAK inhibitors approved by the FDA to treat myelofibrosis, but no previous studies have compared these drugs with each other for treating myelofibrosis in people with low blood cell counts who haven't been treated yet.

• Study Type: Interventional
• Enrollment (Estimated): 268
• Phase: Phase 4

Contacts and Locations

• Study Contact: Name: SWOG Clinical Trials Partnerships SWOG Clinical Trials Partnerships; Phone Number: 210-614-8808; Email: ctp@swog.org

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Registration Step 1: Randomization

Inclusion Criteria:

• Participants must have confirmed diagnosis of primary myelofibrosis (PMF), post-polycythemia vera (PV) MF or post-essential thrombocythemia (ET) MF as assessed by the treating physician per 2022 WHO classification, and confirmed by a bone marrow biopsy within four years.
• Participants must have a spleen measuring ≥ 450 cm3 by MRI within 14 days prior to Step 1 registration. For participants with a medical contraindication to MRI or if MRI is unavailable, a CT scan may be performed.
• Participants must have DIPSS risk category of Intermediate-1, Intermediate-2 or High per Dynamic International Prognostic Scoring System (DIPSS) for MF.
• Participants must have blasts <10% in peripheral blood within 28 days of Step 1 registration. If bone marrow biopsy performed within 28 days prior to Step 1 registration blasts must be <10% as well.
• Participants must have discontinued all drugs used to treat MF, including hydroxyurea, peginterferon alfa-2a, ropeginterferon alfa-2b, anagrelide or busulfan ≥ 14 days prior to Step 1 registration.
• Participants must be ≥ 18 years old at the time of registration.
• Participants must have Zubrod/ECOG Performance Status of 0-2.
• Participants must have a complete medical history and physical exam within 28 days prior to Step 1 registration.
• Participants must meet hematologic parameters within 28 days prior to Step 1 registration.
• Participants must have a calculated creatinine clearance ≥ 30 mL/min using the following Cockcroft-Gault Formula. This specimen must have been drawn and processed within 28 days prior to Step 1 registration. For creatinine clearance formula see the tools on the CRA Workbench https://txwb.crab.org/TXWB/Tools.aspx.
• Participants must be able to take orally administered medication and comply with the oral regimen.
• Participants with a history of human immunodeficiency virus (HIV)-infection must be on effective anti-retroviral therapy at Step 1 registration and have undetectable viral load test on the most recent test results obtained within 6 months prior to Step 1 registration.
• Participants with a history of chronic hepatitis B virus (HBV) infection must have undetectable HBV viral load while on suppressive therapy on the most recent test results obtained within 6 months prior to Step 1 registration, if indicated.
• Participants with a history of hepatitis C virus (HCV) infection must have been treated and cured. Participants currently being treated for HCV infection must have undetectable HCV viral load test on the most recent test results obtained within 6 months prior to Step 1 registration, if indicated.
• Participants must be offered the opportunity to participate in specimen banking.
• Participants who can complete PRO and QOL questionnaires in English or Spanish languages must agree to participate in the patient-reported outcomes and quality of life questionnaires.
• Participants or their legally authorized representative must be informed of the investigational nature of this study and must sign and give informed consent in accordance with institutional and federal guidelines. For participants with impaired decision-making capabilities, legally authorized representatives may sign and give informed consent on behalf of study participants in accordance with applicable federal, local, and WCG IRB regulations.

Exclusion Criteria:

• Participants must have discontinued all drugs used to treat MF, including hydroxyurea, peginterferon alfa-2a, ropeginterferon alfa-2b, anagrelide or busulfan ≥ 14 days prior to Step 1 registration.
• Participants must not be considered eligible for hematopoietic stem cell transplantation (HSCT) or have prior HSCT for MF.
• Participants must not have received prior JAK or ACVR1 inhibitor treatment.
• Participants must not have received investigational therapy within 14 days prior to Step 1 registration.
• Participants must not have had a prior splenectomy.
• Participants must not have had splenic irradiation within 90 days prior to Step 1 registration.
• Participants must not have received prior chemotherapy for their MF (e.g., hypomethylating agent, hypomethylating agent + venetoclax).
• Participants must not have had major surgery within 21 days prior to Step 1 registration.
• Participants must not have received a live vaccine within 14 days prior to Step 1 registration.
• Participants must not have grade 2 or higher peripheral neuropathy.
• Participants must not have clinically significant cardiac disease (New York Heart Association Class III or IV); symptomatic congestive heart failure; or unstable angina pectoris. Participants with known history or current symptoms of cardiac disease, or history of treatment with cardiotoxic agents, must have a clinical risk assessment of cardiac function using the New York Heart Association Functional Classification.
• Participants must not have impairment of gastrointestinal (GI) function or GI disease that may significantly alter the absorption of the study drugs (e.g. ulcerative diseases, uncontrolled nausea, vomiting, diarrhea, malabsorption syndrome, or small bowel resection).
• Participants must not have history of stroke, reversible ischemic neurologic deficit, or transient ischemic attack within 90 days prior to Step 1 registration.
• Participants must not have a prior or concurrent malignancy whose natural history or treatment (in the opinion of the treating physician) has the potential to interfere with the safety or efficacy assessment of the investigational regimen. Participants with curatively treated basal or squamous cell skin cancer, superficial bladder cancer, in situ cervical cancer and/or in situ breast cancer may be enrolled.
• Participants must not have uncontrolled systemic fungal, bacterial, viral or other infection (defined as exhibiting ongoing signs/symptoms related to the infection and without improvement, despite appropriate antibiotics or other treatment) as determined by the local investigator.
• Participants must not be pregnant or nursing (nursing includes breast milk fed to an infant by any means, including from the breast, milk expressed by hand, or pumped). Individuals who are of reproductive potential must have agreed to use an effective contraceptive method with details provided as a part of the consent process. A person who has had menses at any time in the preceding 12 consecutive months or who has semen likely to contain sperm is considered to be of "reproductive potential." In addition to routine contraceptive methods, "effective contraception" also includes refraining from sexual activity that might result in pregnancy and surgery intended to prevent pregnancy (or with a side-effect of pregnancy prevention) including hysterectomy, bilateral oophorectomy, bilateral tubal ligation/occlusion, and vasectomy with testing showing no sperm in the semen.

Registration Step 2: Optional Crossover for All Participants after Week 24 Assessment

Inclusion Criteria:

• Participants must have met one or more of the following criteria on Registration Step 1:

  1. Spleen volume decrease <10% or spleen volume increase of any volume from baseline MRI (or CT) in response to initial treatment (momelotinib or ruxolitinib) from baseline MRI (or CT) at week 24.
  2. ≥ 3 units of RBC transfusions during any rolling 8-week period starting at or after week 16 preceding Step 2 registration OR hemoglobin < 8 g/dL on two consecutive measurements at least 1 week apart during any rolling 8-week period starting at or after week 16 preceding Step 2 registration.
  3. Unacceptable toxicities attributed to initial treatment (momelotinib or ruxolitinib) of grade ≥ 3 (or grade < 3 if determined clinically significant by treating physician) as determined by treating physician.
  4. Unable to maintain total daily ruxolitinib dose ≥ 20 mg due to cytopenias or intolerance (crossover to momelotinib only).
• Participants must be able to safely receive the crossover drug (either momelotinib or ruxolitinib) in the opinion of the treating investigator.
• Participants must have adequate organ and marrow function within 14 days prior to Step 2 registration.
• Participants must have a calculated creatinine clearance ≥ 30 mL/min using the following Cockcroft-Gault Formula. This specimen must have been drawn and processed within 14 days prior to Step 2 registration. For creatinine clearance formula see the tools on the CRA Workbench https://txwb.crab.org/TXWB/Tools.aspx.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Momelotinib	Drug: Momelotinib; 200 mg daily x 96 weeks.; Other Names: JAK-inihibitor
Active Comparator: Ruxolitinib	Drug: Ruxolitinib; Twice daily per treating investigator discretion not to exceed protocol specified guidelines.; Other Names: JAK-inihibitor

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
To estimate and compare the proportion of participants achieving a dual response [SVR35] and transfusion independence response from red blood cell transfusions.	To estimate and compare the proportion of patients achieving a dual response both spleen response [SVR35] and transfusion independence response [TI-R] from red blood cell transfusions at week 24 post-Step 1 randomization in JAK-inhibitor naïve participants with myelofibrosis treated with momelotinib versus ruxolitinib.	24 weeks after randomization

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
TI-R Rate	To estimate and compare the TI-R rate at week 24, post-Step 1 randomization in each treatment arm.	24 weeks after Step 1 Randomization
SVR35 at week 24 post-randomization	To estimate and compare the rates of SVR35 at week 24 post-randomization in each treatment arm.	24 weeks after Step 1 Randomization
OS	To estimate overall survival (OS) in each treatment arm.	96 weeks after Step 1 Randomization
PFS	To estimate progression-free survival (PFS) in each treatment arm.	96 weeks after Step 1 Randomization
SVR35 at week 24 post-randomization	To estimate and compare SVR35 at week 24 post-randomization in each treatment arm with a sensitivity analysis based on a modeled version of the continuous spleen response rate.	24 weeks after Step 1 Randomization
Allogeneic Transplantation	To tabulate the proportion of participants in each arm who undergo allogeneic transplantation at week 24 and week 48 post-Step 1 randomization.	96 weeks after Step 1 Randomization
Cross-over	To tabulate the number of participants on each arm who cross over.	72 weeks after Step 1 Randomization
Time to next non-protocol treatment	To estimate and compare the time to next non-protocol treatment (excludes crossover) in each treatment arm.	96 weeks after Step 1 Randomization
SVR35	To estimate and compare the rates of SVR35 at week 48 post-Step 1 randomization by treatment arm and stratified by cross-over-status.	48 weeks after Step 1 Randomization
TI-R	To estimate and compare the rates of TI-R at week 48 post-Step 1 randomization by treatment arm and stratified by cross-over-status.	48 weeks after Step 1 Randomization
Dual Response	To estimate and compare the rates of dual response (SVR35 + TI-R) at week 48 post-Step 1 randomization by treatment arm and stratified by cross-over-status.	48 weeks after Step 1 Randomization
To estimate the frequency of and severity of toxicities in each treatment arm	To estimate and compare the frequency of major anemia response per 2024 IWG-ELN criteria in each treatment arm by week 24 and by week 48 (week 48 stratified by cross-over-status).	48 weeks after Step 1 Randomization
Major anemia response	To estimate and compare the frequency of major anemia response per 2024 IWG-ELN criteria in each treatment arm by week 24 and by week 48 (week 48 stratified by cross-over-status).	48 weeks after Step 1 Randomization
Time to initiation of anemia-directed therapy	To estimate and compare the time to initiation of anemia-directed therapy in each treatment arm among participants not on anemia-directed therapy at registration by week 24 and by week 48 (week 48 stratified by cross-over-status).	48 weeks after Step 1 Randomization

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Symptom Burden	To compare symptom burden by arm at week 24 using the Myelofibrosis Symptom Assessment Form version 4.0 (MF-SAF v4.0) total score and the Functional Assessment of Cancer Therapy - Anemia (FACT-An) total score	96 weeks after Step 1 Randomization
MF-SAF Scores	To compare by arm individual item scores from the MF-SAF v4.0.	96 weeks after Step 1 Randomization
FACT-An Scores	To compare by arm individual item subscale scores from the FACT-An.	96 weeks after Step 1 Randomization
Longitudinal Trajectories	To examine by arm differences in longitudinal trajectories over time in the MF-SAF v4.0 total score, the FACT-An total score, and MF-SAF v4.0 item scores and FACT-An subscale scores.	96 weeks after Step 1 Randomization
Specimen Banking	To bank specimens for future correlative studies.	96 weeks after Step 1 Randomization

Collaborators and Investigators

• Sponsor: SWOG Cancer Research Network
• Collaborators: GlaxoSmithKline
• Investigators: Principal Investigator: Alexander Coltoff, MD, SWOG Network Cancer Center

Study record dates

Study Major Dates

• Study Start (Estimated): August 8, 2026
• Primary Completion (Estimated): August 8, 2029
• Study Completion (Estimated): August 8, 2031

Study Registration Dates

• First Submitted: March 20, 2026
• First Submitted That Met QC Criteria: March 25, 2026
• First Posted (Actual): March 27, 2026

Study Record Updates

• Last Update Posted (Actual): April 9, 2026
• Last Update Submitted That Met QC Criteria: April 3, 2026
• Last Verified: March 1, 2026

More Information

Terms related to this study

• Keywords: Myelofibrosis; ruxolitinib; momelotinib
• Additional Relevant MeSH Terms: Hematologic Diseases; Bone Marrow Diseases; Myeloproliferative Disorders; Hemic and Lymphatic Diseases; Primary Myelofibrosis; N-(cyanomethyl)-4-(2-((4-(4-morpholinyl)phenyl)amino)-4-pyrimidinyl)benzamide; ruxolitinib
• Other Study ID Numbers: 26CTP.LEUK02

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No