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A Study of CBX-250 for Relapsed or Refractory Myeloid Leukemias

This study is testing a drug called CBX-250 in people with certain types of myeloid leukemias that have come back or haven't responded to previous treatments. These include high-risk Myelodysplastic Syndrome (MDS), Chronic Myelomonocytic Leukemia (CMML), Acute Myeloid Leukemia (AML), and Chronic Myeloid Leukemia (CML). The main goal is to find out how safe CBX-250 is, what side effects it might cause, and the best dose to give. Participants will receive CBX-250 as an injection under the skin in cycles, continuing until their disease gets worse or side effects become too much. The study plans to enroll 72 participants, including those aged 12 and older for whom other treatment options are limited.

Study design
This is a Phase 1, open-label study, meaning both you and your doctors will know you are receiving CBX-250. It is designed to find the safest and most effective dose of CBX-250, and plans to enroll 72 participants.
What's involved
You would receive CBX-250 as an injection under the skin in 28-day cycles, with a priming phase in the first cycle. Treatment continues until your disease progresses or side effects are too severe.
Compensation
Not stated in the trial record.
Follow-up
The study will measure safety and tolerability until the end of the study, which is approximately 24 months.

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NCT06994676

A Study of CBX-250 in Participants With Relapsed or Refractory Myeloid Leukemias

Recruiting
PHASE1Ages 12+InterventionalTreatment
Crossbow Therapeutics, Inc.
~72 participants
Updated 2026-03-16 on ClinicalTrials.gov
What's tested:CBX-250

At a glance

Recruiting sites
11 of 11 listed sites are recruiting right now
RecruitingSuspended, closed, or not yet open
What they're measuring
To determine the safety, tolerability, RP2D, or MTD if different, and dosing regimen of CBX-250.
Measured over Until the end of study (approximately 24 months)
+4 more outcomes measured

Conditions

High-risk Myelodysplastic Syndrome
Chronic Myelomonocytic Leukemia (CMML)
AML - Acute Myeloid Leukemia
Chronic Myeloid Leukemia

Explore related trials

Acute Myeloid LeukemiaChronic Myeloid Leukemia, BCR-ABL1 PositiveChronic Myelomonocytic LeukemiaMyelodysplastic SyndromeHLA Class I Histocompatibility Antigen, A-0201 Alpha Chain

Where it's being run

11 sites across 9 states
California2
Tennessee2
Florida1
Illinois1
Massachusetts1
Missouri1
New York1
Pennsylvania1

Study leadership

  • Briggs Morrison, MD · STUDY_CHAIR · Crossbow Therapeutics, Inc.

Who to contact

Rachel Ghiraldi
[email protected]
857-301-6432
Email the study team

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Do you actually qualify for this trial?

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Eligibility criteria

Inclusion

Hydroxyurea for cytoreduction can be initiated without restriction related to timing of study entry. Hydroxyurea for cytoreduction can be continued concomitantly with CBX-250, with Study Responsible Physician approval.
Intrathecal chemotherapy at the time of diagnostic lumbar puncture at least 24 hours prior to the start of CBX-250 and may continue prophylactic intrathecal chemotherapy beginning in Cycle 2, at the treating physician's discretion. 12. Hematopoietic Growth Factors: At least 7 days since the completion of therapy with short-acting hematopoietic growth factors and 14 days with long-acting growth factors. 13. Biologics (e.g. monoclonal antibody therapy): At least 28 days or 5 half-lives, whichever is shorter, have elapsed since the completion of therapy with a biologic agent. Any AE related to prior biologic treatment must be resolved to baseline severity or ≤Grade 1. 14. Steroids: At least 7 days since systemic glucocorticoid therapy, unless receiving physiologic dosing (equivalent to ≤10 mg prednisone daily) or cytoreductive therapy. Cytoreductive therapy must have approval of the Study Responsible Physician.
Total bilirubin \<1.5 × the upper limit of normal (ULN) for age or normal conjugated bilirubin, or total bilirubin ≤ 3.0 x ULN with direct bilirubin within normal range in participants with well documented Gilbert's syndrome or hemolysis or who require regular blood transfusions.
Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) \<3 × ULN (unless attributed to leukemic involvement with discussion with the Study Responsible Physician).

Exclusion

Any of the following within the 6 months prior to study entry: myocardial infarction, uncontrolled/unstable angina, congestive heart failure (New York Heart Association Classification Class \>II), life-threatening, uncontrolled arrhythmia, cerebrovascular accident, or transient ischemic attack.
QTc using Fridericia's correction (QTcF) \>480 msec 9. Graft-Versus-Host Disease (GVHD): Active acute or chronic GVHD requiring systemic treatment with immunosuppressive medication. Participants may be on physiological doses of steroids. 10. Concurrent malignancy in the previous 2 years with the exception of basal cell carcinoma of the skin, squamous cell carcinoma of the skin, or carcinoma in situ (eg, breast carcinoma, cervical cancer in situ, melanoma in situ) treated with potentially curative therapy. Concurrent malignancy must be in CR or no evidence of disease (NED) during this timeframe. 11. History of or any concurrent condition, therapy, or laboratory abnormality that in the Investigator's opinion might confound the results of the study, interfere with the participant's participation for the full duration of the study, or is not in the best interest of the participant to participate.

What this trial measures

  • To determine the safety, tolerability, RP2D, or MTD if different, and dosing regimen of CBX-250.Until the end of study (approximately 24 months)

    Frequency and type of DLT

  • To determine the safety, tolerability, RP2D, or MTD if different, and dosing regimen of CBX-250.Until the end of study (approximately 24 months)

    Frequency, duration, and severity of TEAEs, TRAEs, AESIs, and SAEs

  • To determine the safety, tolerability, RP2D, or MTD if different, and dosing regimen of CBX-250.Until the end of study (approximately 24 months)

    Frequency and severity of CRS AEs

  • To determine the safety, tolerability, RP2D, or MTD if different, and dosing regimen of CBX-250.Until the end of study (approximately 24 months)

    Drug withdrawals, drug interruptions, or dose reductions due to adverse events

  • To determine the safety, tolerability, RP2D, or MTD if different, and dosing regimen of CBX-250.Until the end of study (approximately 24 months)

    Incidence/shifts of clinical laboratory abnormalities