for people ages 18-70 (full criteria)
study started
completion around
Principal Investigator
by Divya Koura, MD (ucsd)
Headshot of Divya Koura
Divya Koura



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).

Official Title

A First-In-Human, Open-Label, Multicenter Study of VOR33 in Patients With Acute Myeloid Leukemia Who Are at High-Risk for Leukemia Relapse Following Hematopoietic Cell Transplantation


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.


Leukemia, Myeloid, Acute, Myelodysplastic Syndromes, Leukemia, Acute Myeloid Leukemia, AML, Hematopoietic stem cell transplant, HCT, CD33, Allogeneic, Myelodysplastic Syndromes with excess blasts, MDS, MDS-EB, Cell therapy, Preleukemia, Myeloid Leukemia, Syndrome, Gemtuzumab, VOR33, Mylotarg


You can join if…

Open to people ages 18-70

  1. Must be ≥18 and ≤70 years of age.
  2. Patients with AML must have one of the following groups of features that are known to be a risk factor for leukemia relapse:
    • BM in morphological remission (<5% blasts) with adverse-risk disease related genetics at presentation (according to European Leukemia-Net guidelines [ELN, Döhner 2017]), or
    • Intermediate risk genetics in morphologic remission (<5% blasts) with other recognized high risk criteria such as MRD+ following therapy, or
    • BM with evidence of persistent leukemia 5-10% blasts post induction/salvage therapy. Patients with BM Blast count >10% may participate with Sponsor Medical

      Monitor approval. (Note: these patients may have disease-related genetics of any risk criteria at presentation), or

    • Any patient in second or greater remission.
  3. Patients with MDS must have all of the following:
    • Previous or current IPSS-R score of High or Very High risk; AND
    • Previous or current MDS-IB1 or MDS-IB2 per the 2022 WHO criteria (Khoury 2022)
  4. AML sample from the patient must have evidence of CD33 expression (>0%)
  5. Candidate for HLA-matched allogeneic HCT using a myeloablative conditioning regimen.
  6. Must have a related or unrelated stem cell donor that is a 8/8 match for HLA-A, -B, -C, and -DRB1.
  7. Must have adequate performance status and organ function as defined below:
    1. Performance Status: Karnofsky score of ≥70.
    2. Cardiac: left ventricular ejection fraction (LVEF) ≥50%
    3. Pulmonary: diffusing capacity of lung for carbon monoxide (DLCO), forced vital capacity (FVC), and forced expiratory volume in one second (FEV1) ≥66%.
    4. Renal: estimated glomerular filtration rate (GFR) >60 mL/min
    5. Hepatic: total bilirubin <1.5 × ULN, or if ≥1.5 × ULN direct bilirubin <ULN and ALT/AST <1.5 × ULN (per institutional criteria).

You CAN'T join if...

  1. Prior autologous or allogeneic stem cell transplantation.
  2. Presence of the following disease-related genetics: t(15; 17)(q22; q21), or t(9; 22)(q34; q11), or other evidence of acute promyelocytic leukemia or chronic myeloid leukemia.
  3. Prior treatment with Mylotarg™ (gemtuzumab ozogamicin) in the past 3.5 months.
  4. Active central nervous system (CNS) leukemia.
  5. Patients diagnosed with Gilbert's syndrome.
  6. Uncontrolled bacterial, viral, or fungal infections; or known human immunodeficiency virus (HIV), Hepatitis B, or Hepatitis C infection.


  • University of California San Diego Moores Cancer Center accepting new patients
    La Jolla California 92037 United States
  • Fred Hutchinson Cancer Research Center accepting new patients
    Seattle Washington 98109 United States

Lead Scientist at University of California Health

  • Divya Koura, MD (ucsd)
    Associate Clinical Professor, Medicine, Vc-health Sciences-schools. Authored (or co-authored) 17 research publications


accepting new patients
Start Date
Completion Date
Vor Biopharma
Phase 1/2 research study
Study Type
Expecting 24 study participants
Last Updated