A Phase 1/2 interventional study of VOR33 and Mylotarg in Leukemia, Myeloid, Acute and Myelodysplastic Syndromes, sponsored by Vor Biopharma. Terminated at 15 sites in 2 countries. Open to participants aged 18 Years to 70 Years. Per ClinicalTrials.gov, last updated 2025-07-29.
Sponsored by Vor Biopharma · Phase 1/2, Interventional, and Treatment
This is a Phase 1/2a, multicenter, open-label, first-in-human (FIH) study of VOR33 in participants with AML or MDS who are undergoing human leukocyte antigen (HLA)-matched allogeneic hematopoietic cell transplant (HCT).
High risk acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS) frequently relapses despite hematopoietic stem cell transplant (HCT). Post-HCT targeted therapy to reduce relapse is limited by toxicity to the engrafted cells. VOR33, an allogeneic CRISPR/Cas9 genome-edited hematopoietic stem and progenitor cell (HSPC) therapy product, lacking the CD33 protein, is being investigated for participants with CD33+ AML or MDS at high risk for relapse after HCT to allow post-HCT targeting of residual CD33+ acute AML cells using Mylotarg™ without toxicity to engrafted VOR33 cells. Participants will undergo a myeloablative HCT with matched related or unrelated donor CD34+-selected hematopoietic stem and progenitor cells (HSPCs) engineered to remove CD33 expression (VOR33 product). Mylotarg™ will be given after engraftment for up to 4 cycles. The primary endpoint assessing safety of VOR33 will be the incidence of successful engraftment at 28 days. Part 1 of this study will evaluate the safety of escalating Mylotarg™ dose levels to determine the maximum tolerated dose (MTD) and recommended phase 2 dose (RP2D). Part 2 will expand the number of participants to evaluate the Mylotarg™ RP2D.
3,667 studies on the registry are indexed under Leukemia, Myeloid, Acute; 816 are open to participants now.
This study's enrollment of 67 is above the median of 40 across 3,005 interventional studies indexed under Leukemia, Myeloid, Acute.
Browse Leukemia, Myeloid, Acute studies →Vor Biopharma is the lead sponsor of 7 studies on the registry; 1 is open to participants now.
Counted across the registry records on this site, refreshed daily.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Patients with AML must have one of the following groups of features that are known to be a risk factor for leukemia relapse:
Patients with MDS must have all of the following:
Must have adequate performance status and organ function as defined below:
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Stem cell (bone marrow) transplants. Allogeneic uses cells from a donor; autologous uses your own cells, collected earlier and given back.
A 0–100 scale of how well someone can carry out everyday activities. 100 is no complaints and no signs of illness; 70 is able to look after yourself but not to work or keep up normal activity; 50 is needing considerable help and frequent medical care.
Studies often ask for 60 or 70 and above. Your doctor gives the score.
The share of blood the heart’s main pumping chamber (the left ventricle) pushes out with each beat, measured by an echocardiogram (heart ultrasound) or a MUGA scan. About 50–70% is normal.
From a breathing test (spirometry): how much air you can blow out in the first second. Often given as a percentage of what is expected for your age, height and sex.
GFR (glomerular filtration rate) is how much blood the kidneys filter each minute. It is usually estimated from a blood test — eGFR, by formulas such as CKD-EPI or MDRD — and some studies ask for it to be measured directly instead. Usually given in mL/min/1.73 m².
Check the method, the units and the minimum the study states. A value of 90 or above is in the normal-or-high range, but kidney damage can show in other tests too.
A yellow substance made when red blood cells are broken down, which the liver clears. A high level can mean a problem with the liver or the bile ducts.
Criteria often allow more for people with Gilbert’s syndrome, a harmless inherited condition that raises bilirubin.
The top of the normal range for a blood test, as set by the laboratory that runs it. Each lab prints its own range next to your result.
“≤ 2.5 × ULN” means the result can be up to two and a half times that top value.
Two enzymes measured in a routine blood test of the liver. Higher levels can mean the liver is under strain or damaged. SGPT and SGOT are older names for ALT and AST.
Criteria usually give a limit as a multiple of the upper limit of normal (ULN), often higher when cancer has spread to the liver.
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
Hepatitis C is a virus that infects the liver. An HCV antibody test can stay positive after an infection has cleared (and is occasionally positive without one); an HCV RNA test shows whether the virus is there now.
After treatment, hepatitis C counts as cured when HCV RNA is still undetectable 12 weeks or more after the treatment ended. Studies often accept people cured this way.
Allogeneic and autologous transplant
Stem cell (bone marrow) transplants. Allogeneic uses cells from a donor; autologous uses your own cells, collected earlier and given back.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Karnofsky performance status (KPS)
A 0–100 scale of how well someone can carry out everyday activities. 100 is no complaints and no signs of illness; 70 is able to look after yourself but not to work or keep up normal activity; 50 is needing considerable help and frequent medical care.
Studies often ask for 60 or 70 and above. Your doctor gives the score.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
LVEF (left ventricular ejection fraction)
The share of blood the heart’s main pumping chamber (the left ventricle) pushes out with each beat, measured by an echocardiogram (heart ultrasound) or a MUGA scan. About 50–70% is normal.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
FEV1
From a breathing test (spirometry): how much air you can blow out in the first second. Often given as a percentage of what is expected for your age, height and sex.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
GFR and eGFR (kidney filtering)
GFR (glomerular filtration rate) is how much blood the kidneys filter each minute. It is usually estimated from a blood test — eGFR, by formulas such as CKD-EPI or MDRD — and some studies ask for it to be measured directly instead. Usually given in mL/min/1.73 m².
Check the method, the units and the minimum the study states. A value of 90 or above is in the normal-or-high range, but kidney damage can show in other tests too.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Bilirubin
A yellow substance made when red blood cells are broken down, which the liver clears. A high level can mean a problem with the liver or the bile ducts.
Criteria often allow more for people with Gilbert’s syndrome, a harmless inherited condition that raises bilirubin.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ULN (upper limit of normal)
The top of the normal range for a blood test, as set by the laboratory that runs it. Each lab prints its own range next to your result.
“≤ 2.5 × ULN” means the result can be up to two and a half times that top value.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ALT and AST (liver enzymes)
Two enzymes measured in a routine blood test of the liver. Higher levels can mean the liver is under strain or damaged. SGPT and SGOT are older names for ALT and AST.
Criteria usually give a limit as a multiple of the upper limit of normal (ULN), often higher when cancer has spread to the liver.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
HIV
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hepatitis B tests
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hepatitis C tests
Hepatitis C is a virus that infects the liver. An HCV antibody test can stay positive after an infection has cleared (and is occasionally positive without one); an HCV RNA test shows whether the virus is there now.
After treatment, hepatitis C counts as cured when HCV RNA is still undetectable 12 weeks or more after the treatment ended. Studies often accept people cured this way.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
VOR33 infusion followed by Mylotarg Dose Level 1
Biological: VOR33 · Drug: Mylotarg
VOR33 infusion followed by Mylotarg Dose Level 2
Biological: VOR33 · Drug: Mylotarg
VOR33 infusion followed by Mylotarg Dose Level 3
Biological: VOR33 · Drug: Mylotarg
Allogeneic, human leukocyte antigen (HLA) matched, genome edited hematopoietic stem and progenitor cell (HSPC) therapy product lacking the CD33 myeloid protein
Infusion of Mylotarg
Also known as: gemtuzumab ozogamicin
Incidence of neutrophil engraftment
Cumulative incidence of patients who achieve neutrophil engraftment (first day of 3 consecutive days of absolute neutrophil count (ANC) ≥500 cells/mm3) by Day 28.
Time frame: Day 28
Time to neutrophil engraftment
Time to neutrophil engraftment after HCT from Day 0; calculated as the first day of 3 consecutive laboratory values obtained on separate days where the ANC is ≥500 cells/mm3.
Time frame: Up to approximately 28 days
Time to platelet recovery
Time to platelet recovery defined as first day of a sustained platelet count \>20,000/ μL with no platelet transfusion in the preceding seven days.
Time frame: Up to approximately 60 days
Incidence of acute GVHD Grade (G) G2-G4 and G3-G4
Time frame: Up to 24 months
Incidence of chronic GVHD (all and moderate-severe)
Time frame: Up to 24 months
Incidence of primary and secondary graft failure
Incidence of primary and secondary graft failure measured by day 28 post HCT. Secondary graft failure is defined as initial neutrophil engraftment by Day 28 followed by subsequent decline.
Time frame: Up to 24 months
Incidence of toxicities to determine the MTD and RP2D of Mylotarg™
Time frame: Approximately day 60 until 24 months
Incidence of transplant-related mortality (TRM) post HCT
Time frame: Day 100, 12 months, 24 months
Percentage of CD33-negative myeloid cells
Percent donor myeloid chimerism and CD33-negative myeloid cells in peripheral blood.
Time frame: Day 28, 60, 100, 180, and Months 12 and 24
Relapse-free Survival (RFS)
Cumulative incidence of RFS
Time frame: Months 12 and 24
Overall Survival (OS)
OS defined as the time from HCT to the date of death from any cause
Time frame: Months 12 and 24
This study is terminated, as verified in May 2025. You cannot join it, but the record below documents what was studied.
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