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High-risk Myelodysplastic SyndromePhase 1CROSSCHECK-001NCT06994676

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

A Phase 1 study testing CBX-250 in people with High-risk Myelodysplastic Syndrome and Chronic Myelomonocytic Leukemia (CMML), run by Crossbow Therapeutics, Inc. at 11 sites in United States.

Recruiting

Looking for participants now. Contact the study team or a site below to ask about taking part.

Sites and contacts
Official record
Search all trials

Trial summary

Study CBX-250-001 is a Phase 1, open-label, dose-escalation study of CBX-250 in participants with relapsed/refractory AML, HR-MDS, CMML, and CML. Participants aged ≥ 12 years are planned to be enrolled. CBX-250 will initially be investigated on a fixed step-up dosing schedule. Read more about this study

Who is it for?
Ages 12 years and older
What is being tested?
CBX-250
Type of treatment
Injection or infusion
Could I receive a placebo?
No, everyone receives an active treatment
How many people
72 participants
Where
11 sitesUnited States
Study dates
16 Jul 2025to Jun 2027
Phase
Phase 1
Are there results?
Not yet: the study is under way

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

  • Ages 12 years and older
  • All sexes
  • No healthy volunteers
  • Child, Adult, Older adult

Who may be able to join

  • Participants are eligible to be included in the study only if all of the following criteria apply:
  • Age
  • Dose Escalation: Male or female participants aged ≥18 years.
  • Backfill Cohorts: Male or female participants aged ≥12 years for whom no curative treatment options, including transplantation, are available.
  • Diagnosis \& Disease Characteristics
  • Participants with histological confirmation of advanced hematologic malignancy including:
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  • R/R AML, as defined by standardized criteria (e.g., European LeukemiaNet criteria [Dohner 2022]; after standard of care therapy. Participants with persistent leukemia after initial therapy or with recurrence of leukemia at any time after achieving a response during or after the course of treatment (including HSCT) are eligible.
  • R/R HR-MDS or very high risk MDS as per the Revised International Prognostic Scoring System (IPSS-R; Greenberg 2012) or Molecular International Prognostic Scoring System (IPPS-M, Bernard 2022) who are resistant or refractory to 4-6 cycles of hypomethylating agents (HMA; decitabine or azacitidine).
  • R/R CMML who are resistant or refractory to 4-6 cycles of hypomethylating agents (HMA; decitabine or azacitidine).
  • White blood cells must be below 25,000/µL at time of enrollment. Participants may receive cytoreduction prior to enrollment.
  • Historical documented evidence of HLA-A*02:01 allele positivity.
  • Performance Level
  • ECOG PS score 0-1 (if aged ≥18 years); Karnofsky Performance Scale of ≥70 (if aged ≥16 years and <18 years); Lansky PS of ≥70 (if aged <16 years).
  • Prior Therapy
  • Any prior treatment-related toxicities resolved to ≤Grade 1 prior to enrollment, with the exception of ≤Grade 2 alopecia.
  • Radiation Therapy: At least 60 days from prior total body irradiation, craniospinal radiation and/or ≥50% radiation of the pelvis, or at least 14 days from local palliative radiation therapy (small port).
  • Stem Cell Infusion: At least 60 days must have elapsed from HSCT and at least 4 weeks (from first dose) must have elapsed from donor lymphocyte infusion without conditioning.
  • Immunotherapy: At least 42 days since prior immunotherapy, including tumor vaccines and checkpoint inhibitors, and at least 21 days since receipt of chimeric antigen receptor therapy.
  • Anti-Leukemia Therapy: At least 14 days since the completion of anti-leukemic therapy (for example, but not limited to, small molecule or cytotoxic/myelosuppressive therapy), with the following exceptions:
  • 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.
  • 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.
  • 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.
  • 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.
  • Adequate Organ Function Requirements within 10 Days of Treatment Initiation
  • Estimated glomerular filtration rate ≥ 45 mL/min/1.73 m2 based on local institutional practice for age-appropriate determination (eg, Schwartz formula for pediatric participants or Cockcroft-Gault formula for adults).
  • Participants ≥18 years: glomerular filtration rate ≥45 mL/min
  • Participants <18 years: ≥45 mL/min x (participant's body surface area m2/1.73) • Adequate liver function defined as:
  • 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).
  • Sex and Contraceptive/Barrier Requirements
  • If a female of childbearing potential, willing to use a highly effective method of contraception or double barrier method from the time of enrollment through 120 days following the last study drug dose.
  • If male of childbearing potential, agrees to use barrier contraception from the time of enrollment through 120 days following the last study drug dose.
  • Informed Consent
  • Participant or participant's health care proxy is able and willing to provide written informed consent and able to follow study instructions.

Who cannot join

  • Participants are excluded from the study if any of the following criteria apply:
  • Diagnosis
  • Previous CTSG targeted therapy or treatment with any pMHC T-cell engager.
  • Isolated extramedullary relapse.
  • Active central nervous system (CNS) disease. Participants with prior CNS history can be enrolled if the participant has a negative lumbar puncture following completion of intrathecal chemotherapy).
  • Infection
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  • Known HIV infection.
  • Active hepatitis B infection (participants with documented clearance following treatment are allowed).
  • Active hepatitis C infection (participants with documented clearance following treatment are allowed).
  • Pregnancy and Breastfeeding
  • Pregnant or nursing women: Negative serum pregnancy tests are required during Screening and a negative serum or urine pregnancy test is required within 72 hours prior to receiving the first study drug administration, in females of childbearing potential. If the urine test is positive or cannot be confirmed as negative, a serum pregnancy test will be required.
  • Concurrent Conditions
  • Cardiac Disease:
  • 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
  • Graft-Versus-Host Disease (GVHD): Active acute or chronic GVHD requiring systemic treatment with immunosuppressive medication. Participants may be on physiological doses of steroids.
  • 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.
  • 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.
  • Concomitant Medications and Interventions
  • Any commercially available or investigational anti-leukemic therapy other than CBX-250, with the following exceptions:
  • Intrathecal chemotherapy for CNS prophylaxis is permitted after C1 is complete, at the treating physician's discretion.
  • Participation in another therapeutic interventional clinical study in which an investigational agent was administered within 14 days or 5-halflives, whichever is shorter, of starting CBX-250. Participants may continue with non-interventional follow-up from previous clinical studies.
  • Any concurrent systemic treatment to prevent GVHD. Topical treatments for GVHD are permitted.
  • Known allergy or sensitivity to study drug, including excipients.

Trial locations and contacts

11 sites in 1 country. Contact the study team or a site near you to ask about taking part.

Rachel Ghiraldi contact

857-301-6432

rachel.ghiraldi@crossbowtx.com

11 sites in 1 country

United States11 sites, 11 recruiting

  • Dana Farber Cancer Institute

    Boston, Massachusetts, 02215

    Megan Forsyth, 857-215-1405, Megan_Forsyth@DFCI.HARVARD.EDU

    Evan Chen, MD

    Recruiting

  • Northwestern Medicine

    Chicago, Illinois, 60611

    312-695-9367, cancer@northwestern.edu

    Jessica Altman, MD

    Recruiting

  • City of Hope

    Duarte, California, 91010

    Mariah Santoscoy, 626-218-2927, msantoscoy@coh.org

    Brian Ball, MD

    Recruiting

  • MD Anderson Cancer Center

    Houston, Texas, 77030

    Ghayas Issa, MD, 713-745-6798, GCIssa@mdanderson.org

    Ghayas Issa, MD

    Recruiting

  • Sarah Cannon Cancer Institute

    Nashville, Tennessee, 37203

    askSARAH, 844-482-4812

    Stephen Strickland, MD

    Recruiting

  • Vanderbilt University Medical Center

    Nashville, Tennessee, 37232

    Somedeb Ball, MD, 615-322-8973, Somedeb.Ball@vumc.org

    Somedeb Ball, MD

    Recruiting

  • Memorial Sloan Kettering Cancer Center

    New York, New York, 10065

    Eytan Stein, MD, steine@mskcc.org

    Eytan Stein, MD

    Recruiting

  • Stanford Medical Center

    Palo Alto, California, 94304

    Gabriel Mannis, MD, gmannis@stanford.edu

    Gabriel Mannis, MD

    Recruiting

  • Thomas Jefferson University Hospital

    Philadelphia, Pennsylvania, 19107

    Elizabeth Waugh, 267-408-7961, Elizabeth.Waugh@jefferson.edu

    Gina Keiffer, MD

    Recruiting

  • Washington University in St. Louis

    St Louis, Missouri, 63110

    Morgan Swanner, 314-454-8304, swanner@wustl.edu

    John DiPersio, MD

    Recruiting

  • Moffitt Cancer Center

    Tampa, Florida, 33612

    David Sallman, MD

    Recruiting

Other trials in United States

About this study

Official title: CROSSCHECK-001: A Phase 1, Open-Label, Dose-Escalation Study to Evaluate Safety, Tolerability, and Clinical Activity of CBX-250 in Participants With Relapsed or Refractory Myeloid Leukemias

Study CBX-250-001 is a Phase 1, open-label, dose-escalation study of CBX-250 in participants with relapsed/refractory AML, HR-MDS, CMML, and CML. Participants aged ≥ 12 years are planned to be enrolled. CBX-250 will initially be investigated on a fixed step-up dosing schedule. CBX-250 will be administered subcutaneously in 28-day cycles, with the first study drug dose administered on Cycle 1, Day 1. Cycle 1 will consist of a priming phase over 7 days, and a target phase over 28 days. Participants will continue CBX-250 until progressive disease (PD) or unacceptable toxicity. All subsequent treatment cycles will be 28 days.

Being tested
CBX-250
Keywords
AML, HR-MDS, CMML, acute leukemia, CBX-250, CBX-250-001, CROSSCHECK, CROSSCHECK-001, Crossbow, CML
Medical subject headings
Leukemia, Myelomonocytic, Chronic, Leukemia, Myeloid, Acute, Leukemia, Myelogenous, Chronic, BCR-ABL Positive

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • CBX-250Drug

    subcutaneous CBX-250

Study groups in NCT06994676
Study groupRoleWhat they receive
CBX-250Experimentalsubcutaneous CBX-250
Receives: Drug: CBX-250

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. To determine the safety, tolerability, RP2D, or MTD if different, and dosing regimen of CBX-250.

    Frequency and type of DLT

    Measured: Until the end of study (approximately 24 months)

  2. To determine the safety, tolerability, RP2D, or MTD if different, and dosing regimen of CBX-250.

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

    Measured: Until the end of study (approximately 24 months)

  3. To determine the safety, tolerability, RP2D, or MTD if different, and dosing regimen of CBX-250.

    Frequency and severity of CRS AEs

    Measured: Until the end of study (approximately 24 months)

  4. To determine the safety, tolerability, RP2D, or MTD if different, and dosing regimen of CBX-250.

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

    Measured: Until the end of study (approximately 24 months)

  5. To determine the safety, tolerability, RP2D, or MTD if different, and dosing regimen of CBX-250.

    Incidence/shifts of clinical laboratory abnormalities

    Measured: Until the end of study (approximately 24 months)

Secondary outcomes (16)

  1. AUC0-t (first dose and at steady state)

    Area under the plasma concentration-time curve from time 0 to time of last measurable concentration (AUC0-t) of CBX-250 and relevant metabolites

    Measured: Approximately 1 year

  2. Cmax

    Maximum plasma concentration (Cmax) of CBX-250 and relevant metabolites

    Measured: Approximately 1 year

  3. Tmax

    Time to observed maximum plasma concentration of CBX-250 and relevant metabolites

    Measured: Approximately 1 year

  4. ADAs

    Incidence and severity of anti-drug antibodies

    Measured: Approximately 1 year

  5. ORR

    To assess the overall response rate (ORR) of CBX-250

    Measured: Approximately 1 year

  6. CR+CRh rate in AML

    To assess the complete remission (CR) and complete remission with partial hematologic recovery (CRh) rate

    Measured: Approximately 1 year

  7. EFS

    To assess the event free survival (EFS) of CBX-250

    Measured: Approximately 3 years

  8. OS

    To assess overall survival (OS) of CBX-250

    Measured: Approximately 3 years

  9. DOR

    To assess the duration of response (DOR) of CBX-250

    Measured: Approximately 3 years

  10. CRc rate in AML

    To assess the composite definition of complete remission (CRc) rate

    Measured: Approximately 3 years

  11. Remission rate in HR-MDS

    Remission rate as defined by Zeidan 2023: CR, CR equivalent, partial remission (PR), CRL (CRuni and CRbi), CRh, Hematologic improvement (HI)

    Measured: Approximately 1 year

  12. PFS

    To assess the progression free survival (PFS) of CBX-250

    Measured: Approximately 3 years

  13. CR+CRh rate in HR-MDS

    CR+ CR equivalent+ CRL + CRh

    Measured: Approximately 1 year

  14. Transfusion independence

    Any transfusion-free period lasting for at least 56 consecutive days, during which the participant is either on CBX-250 therapy or after cessation of CBX-250 therapy but prior to the start of new therapy

    Measured: Approximately 3 years

  15. To assess the preliminary anti-leukemic activity of CBX-250 in participants with CMML

    Proportion of participants achieving complete response (CR), complete cytogenetic remission, partial response (PR), marrow response, and clinical benefit according to the 2015 International Consortium Proposal of Uniform Response Criteria for Myelodysplastic Syndromes (MDS)/Myeloproliferative Neoplasms (MPN).

    Measured: Approximately 1 year.

  16. To assess the preliminary anti-CML activity of CBX-250 in participants with CML

    Proportion of participants achieving a

    ≥1-log10 reduction in BCR::ABL1 transcript levels from pre-treatment baseline at Week 12 (Day 169 ± 7 days), measured on the International Scale (IS) by centralized realtime quantitative PCR (RT-qPCR)

    Measured: Approximately 1 year.

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted29 May 2025
  2. Study start16 Jul 2025
  3. Primary completionJan 2027 (estimated)
  4. Study completionJun 2027 (estimated)

Resources

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design
Study type
Interventional
Phase
Phase 1
Primary purpose
Treatment
Allocation
Not applicable
Intervention model
Sequential
Masking
None (open label)
Enrolment
72 participants (estimated)
IDs, dates and publications
ClinicalTrials.gov ID
NCT06994676
Sponsor's protocol ID
CBX-250-001
Acronym
CROSSCHECK-001
Status last verified
Mar 2026
First submitted
13 May 2025
Last updated
16 Mar 2026
Results posted
No
Data monitoring committee
Yes
FDA-regulated drug
Yes
FDA-regulated device
No
Individual data sharing
Yes: It is anticipated that the results of this study may be presented at scientific meetings and/or published in a peer reviewed scientific or medical journal.

Questions about this trial

What is this clinical trial studying?

A Phase 1 study testing CBX-250 in people with High-risk Myelodysplastic Syndrome and Chronic Myelomonocytic Leukemia (CMML), run by Crossbow Therapeutics, Inc. at 11 sites in United States.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 35 inclusion and 24 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: looking for participants now, as of the sponsor's last update on 16 Mar 2026. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 11 sites in United States. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

What does this phase mean?

Phase 1 studies test a treatment in a small group of people for the first time or in a new way, mainly to check safety and find the right dose.

Not every study follows the same path, and some studies (observational studies, device studies) have no phase.

Are results available for this study?

This study is still under way. Results are not available in the source record yet.

How can a doctor refer a patient or contact the research team?

Contact Rachel Ghiraldi (857-301-6432, rachel.ghiraldi@crossbowtx.com), or a site near the patient. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

To determine the safety, tolerability, RP2D, or MTD if different, and dosing regimen of CBX-250. (time frame: Until the end of study (approximately 24 months)). The study lists 5 primary outcomes in all. It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT06994676.

Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 16 Mar 2026; AzTrials last refreshed its copy on 7 Nov 2026.

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