Advanced Solid TumorsPhase 1TelOscopeNCT07779798
A Phase 1, Open-Label, Dose-Escalation Study to Evaluate Safety, Tolerability, and Clinical Activity of CBX-663 in Participants With Relapsed or Refractory Myeloid Malignancies, Advanced Solid Tumors, or Recurrent or Progressive Glioblastoma.
A Phase 1 study testing CBX-663 in people with Advanced Solid Tumors and Recurrent or Progressive Glioblastoma, run by Crossbow Therapeutics, Inc. at 4 sites in United States.
Trial summary
This is a Phase 1, open-label, dose-escalation study of CBX-663 in participants with R/R AML, MDS or CMML (Cohort A), advanced solid tumors (Cohort B), or recurrent or progressive GBM (Cohort C) (collectively called 'indication cohorts'). Participants aged ≥18 years are planned to be enrolled. Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Advanced Solid Tumors, Recurrent or Progressive Glioblastoma, Relapse or Refractory Myeloid Malignancies
- What is being tested?
- CBX-663
- Type of treatment
- Injection or infusion
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 120 participants
- Where
- 4 sitesUnited States
- Study dates
- 4 Aug 2026to Jun 2028
- 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 18 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Cohort A (R/R AML, MDS or CMML) Specific Inclusion Criteria:
- R/R AML, as defined by standardized criteria (e.g., European Leukemia Net criteria (Dohner, 2022) (Arber, 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. Participants must have bone marrow blasts ≥5%.
- R/R MDS as per WHO 2022. Participants must have peripheral or bone marrow blasts <20%, and must have exhausted locally available treatments, including treatments for actionable mutations.
- For High-Risk MDS participants, participants must be resistant to or refractory to at least 4 cycles of hypomethylating agents or have progressed or are intolerant to such agents.
- R/R dysplastic or proliferative CMML participants, participants must be 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.
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- Any prior treatment-related toxicities resolved to Grade ≤1 prior to enrollment, with the exception of Grade ≤2 alopecia.
- Cohort B (Solid Tumor) Specific Inclusion Criteria:
- Histologically or cytologically diagnosed, locally advanced (unresectable) or metastatic solid cancers that have progressed after all available standard therapy for the specific tumor type, or for which no standard therapy exists. Participants for whom standard therapies are intolerable or considered inappropriate by the Investigator are eligible.
- Measurable disease (as defined by RECIST version 1.1).
- Prior Therapy
- Any prior treatment-related toxicities resolved to Grade ≤1 prior to enrollment, with the exception of Grade ≤2 alopecia.
- 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.
- 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.
- Anti-Cancer Therapy: Chemotherapy or small molecule targeted therapy, either investigational or commercially approved and available, within 2 weeks or 5 half-lives (whichever is shorter) prior to the start of study drug administration.
- 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).
- Cohort C (Recurrent/Progressive GBM) Specific Inclusion Criteria:
- Histologically confirmed or molecularly defined diagnosis of glioblastoma (IDH-wildtype) according to WHO 2021.
- Historical documented evidence of a TERT promoter mutation.
- Radiographic evidence of recurrent or progressive disease following prior first-line radiotherapy, defined as progression per RANO 2.0 criteria, as determined by investigator assessment. Prior use of tumor-treating fields is allowed but not required (Wen, 2023).
- Measurable (at least 1 cm x 1 cm) enhancing tumor.
- Any prior treatment-related toxicities resolved to ≤Grade 1 prior to enrollment, with the exception of ≤Grade 2 alopecia and ≤Grade 2 fatigue.
- Aged ≥18 years.
- Backfill Cohorts: Participants for whom no curative treatment options, including transplantation, are available.
- Historical documented evidence of HLA-A*02:01 allele positivity.
- ECOG PS score 0-1. Adequate Organ Function Requirements within 10 Days of Treatment Initiation
- Estimated glomerular filtration rate (eGFR) ≥60 mL/min/1.73 m2 based on local institutional practice (e.g., Cockcroft-Gault formula).
- 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 or tumor involvement with discussion with the Study Responsible Physician).
- 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.
- 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
- Cohort C (Recurrent/Progressive GBM) Specific Exclusion Criteria:
- Known or suspected leptomeningeal disease are excluded, defined as radiographic evidence of leptomeningeal involvement on MRI of the brain and/or spine, or positive cerebrospinal fluid (CSF) cytology, at screening or prior to first dose.
- Tumors involving the brainstem or spinal cord are excluded, including primary tumors arising from, or metastatic lesions involving, the brainstem (midbrain, pons, or medulla) or spinal cord.
- Received prior bevacizumab or any other anti-VEGF or anti-VEGFR therapy.
- Absolute lymphocyte count <800/uL.
- Clinically significant mass effect or midline shift.
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- Previous treatment with any pHLA-targeting 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.
- Note: this does not apply to Cohort C GBM participants
- 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).
- Any acute or chronic infection requiring systemic treatment
- 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.
- 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 GVHD.
- 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 (e.g., 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.
- Current or historical diagnosis of a gastrointestinal autoimmune or inflammatory condition, including but not limited to ulcerative colitis (UC), Crohn's disease (CD), indeterminate colitis, or microscopic colitis (collagenous or lymphocytic colitis), or a history of GI toxicity from previous therapy that, in the opinion of the investigator, should preclude study participation.
- Significant impairment of lung function requiring chronic use of ambulatory supplemental oxygen.
- Screening laboratory values or investigations that do not meet the requirements for adequate organ function.
- 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.
- Any commercially available or investigational anti-leukemic or anti-cancer therapy other than CBX 663, with the following exceptions:
- Intrathecal chemotherapy for CNS prophylaxis is permitted after C1 is complete, at the treating physician's discretion.
- Participants who experienced severe, life-threatening or recurrent (≥ Grade 2) immune-mediated adverse events or infusion-related reactions including those that led to permanent discontinuation while on previous treatment with immuno-oncology agents.
- Any concurrent systemic treatment to prevent GVHD. Topical treatments for GVHD are permitted. Participants who stopped calcineurin inhibitor (CNI) prophylaxis should be off CNI for at least 4 weeks.
- Known allergy or sensitivity to study drug, including excipients.
Trial locations and contacts
4 sites in 1 country. Contact the study team or a site near you to ask about taking part.
United States4 sites, 4 recruiting
- Recruiting
City of Hope
Duarte, California, 91010
Ian Lagman, 626-218-4976, ilagman@coh.org
Brian Ball, MD
- Recruiting
NEXT Oncology- Virginia
Fairfax, Virginia, 22031
Maybelle De La Rosa, 703-783-4518, mdelarosa@nextoncology.com
Alexander Spira, MD
- Recruiting
The University of Texas, MD Anderson Cancer Center
Houston, Texas, 77030
Nicholas Short, MD, 713-563-4485, nshort@mdanderson.org
Nicholas Short, MD
- Recruiting
H Lee Moffitt Cancer Center & Research Institute
Tampa, Florida, 33612
Malko Cajuste, 813-745-4498, Malko.cajuste@moffitt.org
David Sallman, MD
About this study
This is a Phase 1, open-label, dose-escalation study of CBX-663 in participants with R/R AML, MDS or CMML (Cohort A), advanced solid tumors (Cohort B), or recurrent or progressive GBM (Cohort C) (collectively called 'indication cohorts'). Participants aged ≥18 years are planned to be enrolled. CBX-663 will initially be investigated on a fixed dosing schedule. CBX-663 will be administered intravenously (IV) on Cycle 1 Day 1 (C1D1) and then once weekly (QW) in 21-day cycles. Participants will continue treatment with CBX-663 until unacceptable toxicity, progressive disease, withdrawal of consent, or lack of clinical benefit.
- Conditions
- Advanced Solid Tumors, Recurrent or Progressive Glioblastoma, Relapse or Refractory Myeloid Malignancies
- Being tested
- CBX-663
- Medical subject headings
- Recurrence
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
CBX-663Drug
Intravenous (I.V.) CBX-663
| Study group | Role | What they receive |
|---|---|---|
| CBX-663 | Experimental | Intravenous (I.V.) CBX-663 Receives: Drug: CBX-663 |
What is being measured
The primary outcome is the main question the study is designed to answer.
Recommended Phase 2 Dose (RP2D)
To determine the RP2D.
Measured: Until the end of study (approximately 24 months)
To determine safety and tolerability of CBX-663; Dose Limiting Toxicities (DLTs), Treatment-Emergent Adverse Events (TEAEs) and Treatment-Related Adverse Events (TRAEs).
Frequency and type of dose-limiting toxicities (DLT), Frequency, duration, and severity of treatment-emergent adverse events (TEAEs), treatment-related AEs (TRAEs), and serious adverse events (SAEs), Frequency and severity of cytokine release syndrome (CRS) adverse events (AEs), Withdrawal from the study, drug discontinuations, drug interruptions, or dose reductions due to adverse events Incidence/shifts of clinical laboratory abnormalities
Measured: From enrollment through 30 days following end of treatment.
To assess the PK of CBX-663: AUC0-t
Area under the plasma concentration-time curve from time 0 to time of last measurable concentration (AUC0-t) of CBX-663 and relevant metabolites.
Measured: Approximately 1 year.
To assess the PK of CBX-663: Cmax
Maximum plasma concentration (Cmax) of CBX-663 and relevant metabolites.
Measured: Approximately 1 year.
To assess the PK of CBX-663: Tmax
Time to observed maximum plasma concentration of CBX-663 and relevant metabolites
Measured: Approximately 1 year.
To assess the PK of CBX-663: Ctau
CBX-663 drug concentration at the end of the dosing interval.
Measured: Approximately 1 year.
To assess the PK of CBX-663: T½
Terminal elimination half-life of CBX-663.
Measured: Approximately 1 year.
To assess the PK of CBX-663: Degree of accumulation
Degree of CBX-663 accumulation in the blood stream and body.
Measured: Approximately 1 year.
To assess the preliminary anti-leukemic activity of CBX-663 in participants with R/R AML (Cohort A):
Objective response rate (ORR), complete response (CR), CR with partial hematologic recovery (CRh), CR with incomplete hematologic recovery (CRi) (Dohner, 2022) CR rate (CR+CRh) CRc Rate (CR+ CRh + CRi)
Measured: From enrollment through 30 days following end of treatment
To assess the preliminary anti-leukemic activity of CBX-663 in participants with R/R CMML (Cohort A)
Response criteria for CMML: evaluated per IWG 2015 (Savona, 2015) in adults with endpoints including CR, PR, complete cytogenetic remission, marrow response and clinical benefit as appropriate
Measured: From enrollment through 30 days following end of treatment.
To assess the preliminary anti-leukemic activity of CBX-663 in participants with R/R MDS (Cohort A):
Best Overall Response (BOR) as defined by MDS/MPN International Working Group (IWG) 2023 (Zeidan, 2023) for Higher-Risk MDS and IWG 2018 (Platzbecker, 2019) for Lower-Risk MDS
Measured: From enrollment through 30 days following end of treatment.
To assess the preliminary anti-leukemic activity of CBX-663 in participants in Cohort A: Duration of Response (DoR)
To assess the duration of response (DoR) of CBX-663.
Measured: From enrollment through 30 days following end of treatment.
To assess the preliminary anti-leukemic activity of CBX-663 in participants in Cohort A: Time to Response (TTR)
To assess the time to response (TTR) of CBX-663.
Measured: From enrollment through 30 days following end of treatment.
To assess the preliminary anti-leukemic activity of CBX-663 in participants with R/R AML, MDS or CMML (Cohort A): CRminimal residual disease (MRD)- rate for participants with CRc.
To assess the CRminimal residual disease (MRD)- rate for participants with CRc of CBX-663.
Measured: From enrollment through 30 days following end of treatment.
To assess the preliminary anti-leukemic activity of CBX-663 in Cohort A: Hematologic Improvement (HI)
HI defined as:
- Not meeting criteria for CR (or CR equivalent) or CRuni or CRL
- HIerythroid (HI-E)
- HIplatelets (HI-P)
- HIneutrophils (HI-N)
Measured: From enrollment through 30 days following end of treatment.
To assess the preliminary anti-leukemic activity of CBX-663 in Cohort A: Transfusion Independence
Transfusion independence defined as any transfusion-free period lasting for at least 56 consecutive days, during which the participant is either on CBX-663 therapy or after cessation of CBX-663 therapy but prior to the start of new therapy.
Measured: From enrollment through 30 days following end of treatment.
To assess the preliminary anti-leukemic activity of CBX-663 in Cohort A: Transfusion burden reduction
To assess the transfusion burden reduction of CBX-663.
Measured: From enrollment through 30 days following end of treatment.
To assess the preliminary anti-leukemic activity of CBX-663 in Cohort A: Rate of leukemic transformation
To assess the rate of leukemic transformation of CBX-663.
Measured: From enrollment through 30 days following end of treatment.
To assess the preliminary anti-leukemic activity of CBX-663 in Cohort A: Event free survival (EFS)
To assess the Event free survival (EFS) of CBX-663.
Measured: From enrollment through 30 days following end of treatment.
To assess the preliminary anti-leukemic activity of CBX-663 in Cohort A: Overall Survival (OS)
To assess the Overall Survival (OS) of CBX-663.
Measured: From enrollment through 30 days following end of treatment.
To assess the preliminary anti-tumor activity of CBX-663 in Cohort B based on Investigator assessment using Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1 criteria: Overall Response Rate (ORR)
To assess overall response rate (ORR) of CBX-663.
Measured: From enrollment through 30 days following the end of treatment.
To assess the preliminary anti-tumor activity of CBX-663 in Cohort B based on Investigator assessment using Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1 criteria: Duration of Response (DoR)
To assess duration of response of CBX-663.
Measured: From enrollment through 30 days following end of treatment.
To assess the preliminary anti-tumor activity of CBX-663 in Cohort B based on Investigator assessment using Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1 criteria: Time to Response (TTR)
To assess time to response (TTR) of CBX-663.
Measured: From enrollment through 30 days following end of treatment.
To assess the preliminary anti-tumor activity of CBX-663 in Cohort B based on Investigator assessment using Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1 criteria: Disease Control Rate (DCR)
To assess disease control rate (DCR) of CBX-663.
Measured: From enrollment through 30 days following end of treatment.
To assess the preliminary anti-tumor activity of CBX-663 in Cohort B based on Investigator assessment using Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1 criteria: Progression Free Survival (PFS)
To assess progression free survival (PFS) of CBX-663.
Measured: From enrollment through 30 days following end of treatment.
To assess the preliminary anti-tumor activity of CBX-663 in Cohort B based on Investigator assessment using Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1 criteria: Overall Survival (OS)
To assess overall survival (OS) of CBX-663.
Measured: From enrollment through 30 days following end of treatment.
To assess the preliminary anti-tumor activity of CBX-663 in participants with recurrent/progressive GBM (Cohort C): Overall Response Rate (ORR)
To assess the overall response rate (ORR) per Response Assessment in Neuro-Oncology (RANO) Criteria 2.0 (Wen 2023) and iRANO
Measured: From enrollment through 30 days following the end of treatment.
To assess the preliminary anti-tumor activity of CBX-663 in Cohort C: Duration of Response (DoR)
To assess duration of response (DoR) of CBX-663.
Measured: From enrollment through 30 days following end of treatment.
To assess the preliminary anti-tumor activity of CBX-663 in Cohort C: Time to Response (TTR)
To assess time to response (TTR) of CBX-663.
Measured: From enrollment through 30 days following end of treatment.
To assess the preliminary anti-tumor activity of CBX-663 in Cohort C: Disease Control Rate (DCR)
To assess disease control rate of CBX-663.
Measured: From enrollment through 30 days following end of treatment.
To assess the preliminary anti-tumor activity of CBX-663 in Cohort C: Progression Free Survival (PFS)
To assess progression free survival (PFS) of CBX-663.
Measured: From enrollment through 30 days following end of treatment.
To assess the preliminary anti-tumor activity of CBX-663 in Cohort C: Overall Survival (OS)
To assess overall survival (OS) of CBX-663.
Measured: From enrollment through 30 days following end of treatment.
To assess the preliminary anti-tumor activity of CBX-663 in Cohort C: Changes in Corticosteroid Use
To assess changes in corticosteroid use in participants with GBM.
Measured: From enrollment through 30 days following end of treatment.
To assess the preliminary anti-tumor activity of CBX-663 in Cohort C: Changes in neurologic function as assessed by the Neurological Assessment in Neuro-Oncology scale
To assess changes in neurologic function as assessed by the Neurological Assessment in Neuro-Oncology scale in participants with GBM.
Measured: From enrollment through 30 days following end of treatment.
Secondary outcomes (1)
To assess the immunogenicity of CBX-663.
Incidence and severity of anti-drug antibodies (ADAs)
Measured: From enrollment through 30 days following the end of treatment.
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted21 Aug 2026
- Study start4 Aug 2026
- Primary completionJan 2028 (estimated)
- Study completionJun 2028 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Advanced Solid TumorsStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
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
- Single group
- Masking
- None (open label)
- Enrolment
- 120 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Crossbow Therapeutics, Inc.
- Sponsor type
- Industry (pharma, biotech, devices)
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07779798
- Sponsor's protocol ID
- CBX-663-001
- Acronym
- TelOscope
- Status last verified
- Oct 2026
- First submitted
- 7 Aug 2026
- Last updated
- 21 Oct 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. A Publications Committee, comprised of Investigators participating in the study and representatives from Crossbow as appropriate, will be formed to oversee any publication or presentation of the study results, which will reflect the experience of all participating study centers. All such publications and presentations must be approved in advance by Crossbow, in its sole discretion. Subsequently, individual Investigators may publish results from the study in compliance with their agreement with the Sponsor.
Study at a glance
From the registry record, last updated by the sponsor on 21 Oct 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A Phase 1, Open-Label, Dose-Escalation Study to Evaluate Safety, Tolerability, and Clinical Activity of CBX-663 in Participants With Relapsed or Refractory Myeloid Malignancies, Advanced Solid Tumors, or Recurrent or Progressive Glioblastoma.
- ClinicalTrials.gov ID
- NCT07779798
- Acronym / sponsor ID
- TelOscope / CBX-663-001
- Conditions
- Advanced Solid Tumors, Recurrent or Progressive Glioblastoma, Relapse or Refractory Myeloid Malignancies
- Phase
- Phase 1
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 120 participants (estimated)
- Lead sponsor
- Crossbow Therapeutics, Inc.Industry (pharma, biotech, devices)
- Study start
- 4 Aug 2026 (actual)
- Primary completion
- Jan 2028 (estimated)
- Study completion
- Jun 2028 (estimated)
- First posted
- 21 Aug 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
This is a Phase 1, open-label, dose-escalation study of CBX-663 in participants with R/R AML, MDS or CMML (Cohort A), advanced solid tumors (Cohort B), or recurrent or progressive GBM (Cohort C) (collectively called 'indication cohorts'). Participants aged ≥18 years are planned to be enrolled. CBX-663 will initially be investigated on a fixed dosing schedule. CBX-663 will be administered intravenously (IV) on Cycle 1 Day 1 (C1D1) and then once weekly (QW) in 21-day cycles. Participants will continue treatment with CBX-663 until unacceptable toxicity, progressive disease, withdrawal of consent, or lack of clinical benefit.
Study design
- Primary purpose
- Treatment
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| CBX-663 | Experimental | Drug: CBX-663Intravenous (I.V.) CBX-663 |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (33 listed)
- R/R AML, as defined by standardized criteria (e.g., European Leukemia Net criteria (Dohner, 2022) (Arber, 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. Participants must have bone marrow blasts ≥5%.
- R/R MDS as per WHO 2022. Participants must have peripheral or bone marrow blasts <20%, and must have exhausted locally available treatments, including treatments for actionable mutations.
- R/R dysplastic or proliferative CMML participants, participants must be 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.
- Any prior treatment-related toxicities resolved to Grade ≤1 prior to enrollment, with the exception of Grade ≤2 alopecia.
Key exclusion criteria (29 listed)
- Known or suspected leptomeningeal disease are excluded, defined as radiographic evidence of leptomeningeal involvement on MRI of the brain and/or spine, or positive cerebrospinal fluid (CSF) cytology, at screening or prior to first dose.
- Tumors involving the brainstem or spinal cord are excluded, including primary tumors arising from, or metastatic lesions involving, the brainstem (midbrain, pons, or medulla) or spinal cord.
- Received prior bevacizumab or any other anti-VEGF or anti-VEGFR therapy.
- Absolute lymphocyte count <800/uL.
- Clinically significant mass effect or midline shift.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| CBX-663Intravenous (I.V.) CBX-663 | Drug | CBX-663 |
Primary outcome
Recommended Phase 2 Dose (RP2D)
Time frame: Until the end of study (approximately 24 months)
To determine the RP2D.
To determine safety and tolerability of CBX-663; Dose Limiting Toxicities (DLTs), Treatment-Emergent Adverse Events (TEAEs) and Treatment-Related Adverse Events (TRAEs).
Time frame: From enrollment through 30 days following end of treatment.
Frequency and type of dose-limiting toxicities (DLT), Frequency, duration, and severity of treatment-emergent adverse events (TEAEs), treatment-related AEs (TRAEs), and serious adverse events (SAEs), Frequency and severity of cytokine release syndrome (CRS) adverse events (AEs), Withdrawal from the study, drug discontinuations, drug interruptions, or dose reductions due to adverse events Incidence/shifts of clinical laboratory abnormalities
To assess the PK of CBX-663: AUC0-t
Time frame: Approximately 1 year.
Area under the plasma concentration-time curve from time 0 to time of last measurable concentration (AUC0-t) of CBX-663 and relevant metabolites.
To assess the PK of CBX-663: Cmax
Time frame: Approximately 1 year.
Maximum plasma concentration (Cmax) of CBX-663 and relevant metabolites.
To assess the PK of CBX-663: Tmax
Time frame: Approximately 1 year.
Time to observed maximum plasma concentration of CBX-663 and relevant metabolites
To assess the PK of CBX-663: Ctau
Time frame: Approximately 1 year.
CBX-663 drug concentration at the end of the dosing interval.
To assess the PK of CBX-663: T½
Time frame: Approximately 1 year.
Terminal elimination half-life of CBX-663.
To assess the PK of CBX-663: Degree of accumulation
Time frame: Approximately 1 year.
Degree of CBX-663 accumulation in the blood stream and body.
To assess the preliminary anti-leukemic activity of CBX-663 in participants with R/R AML (Cohort A):
Time frame: From enrollment through 30 days following end of treatment
Objective response rate (ORR), complete response (CR), CR with partial hematologic recovery (CRh), CR with incomplete hematologic recovery (CRi) (Dohner, 2022) CR rate (CR+CRh) CRc Rate (CR+ CRh + CRi)
To assess the preliminary anti-leukemic activity of CBX-663 in participants with R/R CMML (Cohort A)
Time frame: From enrollment through 30 days following end of treatment.
Response criteria for CMML: evaluated per IWG 2015 (Savona, 2015) in adults with endpoints including CR, PR, complete cytogenetic remission, marrow response and clinical benefit as appropriate
To assess the preliminary anti-leukemic activity of CBX-663 in participants with R/R MDS (Cohort A):
Time frame: From enrollment through 30 days following end of treatment.
Best Overall Response (BOR) as defined by MDS/MPN International Working Group (IWG) 2023 (Zeidan, 2023) for Higher-Risk MDS and IWG 2018 (Platzbecker, 2019) for Lower-Risk MDS
To assess the preliminary anti-leukemic activity of CBX-663 in participants in Cohort A: Duration of Response (DoR)
Time frame: From enrollment through 30 days following end of treatment.
To assess the duration of response (DoR) of CBX-663.
To assess the preliminary anti-leukemic activity of CBX-663 in participants in Cohort A: Time to Response (TTR)
Time frame: From enrollment through 30 days following end of treatment.
To assess the time to response (TTR) of CBX-663.
To assess the preliminary anti-leukemic activity of CBX-663 in participants with R/R AML, MDS or CMML (Cohort A): CRminimal residual disease (MRD)- rate for participants with CRc.
Time frame: From enrollment through 30 days following end of treatment.
To assess the CRminimal residual disease (MRD)- rate for participants with CRc of CBX-663.
To assess the preliminary anti-leukemic activity of CBX-663 in Cohort A: Hematologic Improvement (HI)
Time frame: From enrollment through 30 days following end of treatment.
HI defined as: * Not meeting criteria for CR (or CR equivalent) or CRuni or CRL * HIerythroid (HI-E) * HIplatelets (HI-P) * HIneutrophils (HI-N)
To assess the preliminary anti-leukemic activity of CBX-663 in Cohort A: Transfusion Independence
Time frame: From enrollment through 30 days following end of treatment.
Transfusion independence defined as any transfusion-free period lasting for at least 56 consecutive days, during which the participant is either on CBX-663 therapy or after cessation of CBX-663 therapy but prior to the start of new therapy.
To assess the preliminary anti-leukemic activity of CBX-663 in Cohort A: Transfusion burden reduction
Time frame: From enrollment through 30 days following end of treatment.
To assess the transfusion burden reduction of CBX-663.
To assess the preliminary anti-leukemic activity of CBX-663 in Cohort A: Rate of leukemic transformation
Time frame: From enrollment through 30 days following end of treatment.
To assess the rate of leukemic transformation of CBX-663.
To assess the preliminary anti-leukemic activity of CBX-663 in Cohort A: Event free survival (EFS)
Time frame: From enrollment through 30 days following end of treatment.
To assess the Event free survival (EFS) of CBX-663.
To assess the preliminary anti-leukemic activity of CBX-663 in Cohort A: Overall Survival (OS)
Time frame: From enrollment through 30 days following end of treatment.
To assess the Overall Survival (OS) of CBX-663.
To assess the preliminary anti-tumor activity of CBX-663 in Cohort B based on Investigator assessment using Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1 criteria: Overall Response Rate (ORR)
Time frame: From enrollment through 30 days following the end of treatment.
To assess overall response rate (ORR) of CBX-663.
To assess the preliminary anti-tumor activity of CBX-663 in Cohort B based on Investigator assessment using Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1 criteria: Duration of Response (DoR)
Time frame: From enrollment through 30 days following end of treatment.
To assess duration of response of CBX-663.
To assess the preliminary anti-tumor activity of CBX-663 in Cohort B based on Investigator assessment using Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1 criteria: Time to Response (TTR)
Time frame: From enrollment through 30 days following end of treatment.
To assess time to response (TTR) of CBX-663.
To assess the preliminary anti-tumor activity of CBX-663 in Cohort B based on Investigator assessment using Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1 criteria: Disease Control Rate (DCR)
Time frame: From enrollment through 30 days following end of treatment.
To assess disease control rate (DCR) of CBX-663.
To assess the preliminary anti-tumor activity of CBX-663 in Cohort B based on Investigator assessment using Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1 criteria: Progression Free Survival (PFS)
Time frame: From enrollment through 30 days following end of treatment.
To assess progression free survival (PFS) of CBX-663.
To assess the preliminary anti-tumor activity of CBX-663 in Cohort B based on Investigator assessment using Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1 criteria: Overall Survival (OS)
Time frame: From enrollment through 30 days following end of treatment.
To assess overall survival (OS) of CBX-663.
To assess the preliminary anti-tumor activity of CBX-663 in participants with recurrent/progressive GBM (Cohort C): Overall Response Rate (ORR)
Time frame: From enrollment through 30 days following the end of treatment.
To assess the overall response rate (ORR) per Response Assessment in Neuro-Oncology (RANO) Criteria 2.0 (Wen 2023) and iRANO
To assess the preliminary anti-tumor activity of CBX-663 in Cohort C: Duration of Response (DoR)
Time frame: From enrollment through 30 days following end of treatment.
To assess duration of response (DoR) of CBX-663.
To assess the preliminary anti-tumor activity of CBX-663 in Cohort C: Time to Response (TTR)
Time frame: From enrollment through 30 days following end of treatment.
To assess time to response (TTR) of CBX-663.
To assess the preliminary anti-tumor activity of CBX-663 in Cohort C: Disease Control Rate (DCR)
Time frame: From enrollment through 30 days following end of treatment.
To assess disease control rate of CBX-663.
To assess the preliminary anti-tumor activity of CBX-663 in Cohort C: Progression Free Survival (PFS)
Time frame: From enrollment through 30 days following end of treatment.
To assess progression free survival (PFS) of CBX-663.
To assess the preliminary anti-tumor activity of CBX-663 in Cohort C: Overall Survival (OS)
Time frame: From enrollment through 30 days following end of treatment.
To assess overall survival (OS) of CBX-663.
To assess the preliminary anti-tumor activity of CBX-663 in Cohort C: Changes in Corticosteroid Use
Time frame: From enrollment through 30 days following end of treatment.
To assess changes in corticosteroid use in participants with GBM.
To assess the preliminary anti-tumor activity of CBX-663 in Cohort C: Changes in neurologic function as assessed by the Neurological Assessment in Neuro-Oncology scale
Time frame: From enrollment through 30 days following end of treatment.
To assess changes in neurologic function as assessed by the Neurological Assessment in Neuro-Oncology scale in participants with GBM.
1 secondary outcome
To assess the immunogenicity of CBX-663.
Time frame: From enrollment through 30 days following the end of treatment.
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 21 Oct 2026.
- Individual participant dataSharing planned: 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. A Publications Committee, comprised of Investigators participating in the study and representatives from Crossbow as appropriate, will be formed to oversee any publication or presentation of the study results, which will reflect the experience of all participating study centers. All such publications and presentations must be approved in advance by Crossbow, in its sole discretion. Subsequently, individual Investigators may publish results from the study in compliance with their agreement with the Sponsor.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
H Lee Moffitt Cancer Center & Research Institute
Tampa, United States
The University of Texas, MD Anderson Cancer Center
Houston, United States
4 sites in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 1 study testing CBX-663 in people with Advanced Solid Tumors and Recurrent or Progressive Glioblastoma, run by Crossbow Therapeutics, Inc. at 4 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 33 inclusion and 29 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 21 Oct 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 4 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?
Each site lists its own contact: choose the nearest one under Trial locations. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Recommended Phase 2 Dose (RP2D) (time frame: Until the end of study (approximately 24 months)). The study lists 34 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
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 21 Oct 2026.