Vor Bio, a clinical-stage cell and genome engineering company, has announced encouraging clinical data from its ongoing Phase 1/2 VBP101 study evaluating trem-cel followed by Mylotarg™ in patients with relapsed/refractory acute myeloid leukemia (AML). The data, presented on September 5, 2024, demonstrated reliable engraftment, shielding from Mylotarg's on-target toxicity, a broadened therapeutic window, and early evidence of patient benefit.
VBP101 Trial Results
The data released included 18 patients treated with trem-cel, with ten having received Mylotarg as of the July 19, 2024, data cutoff. Key findings include:
- Reliable Engraftment: 100% of patients achieved primary neutrophil engraftment (median 9 days) and robust platelet recovery (median 16.5 days). High CD33 editing efficiency (median 89%, range 71-94%) and full myeloid chimerism at Day 28 were also observed.
- Shielding of the Blood System: Maintained neutrophil and platelet counts across multiple Mylotarg doses of 0.5, 1, and 2 mg/m2.
- Broadened Therapeutic Index: Drug exposure, represented by AUC, was consistent with labeled Mylotarg doses, while maximal concentrations (Cmax) were well below the known toxic range.
- Early Evidence of Patient Benefit: Measured by relapse-free survival compared to published high-risk AML comparators.
Guenther Koehne, MD, PhD, an investigator on the VBP101 study, noted, "All the hope I had in the safety of this approach has been supported by the data from this trial thus far. I look forward to treating my next patients at high risk of relapse on this trial as their outcomes are otherwise limited with standard transplants."
VCAR33ALLO Progress
Vor Bio is also advancing VCAR33ALLO, another potential synergistic treatment option after trem-cel. The VBP301 study continues to enroll patients, initially focusing on relapsed/refractory AML post-transplant. Encouraging in vivo CAR-T expansion data has been observed from three patients treated at the lowest dose of 1 x 106 CAR+ cells/kg.
New Preclinical Asset: VADC45
Vor Bio introduced VADC45, a new preclinical asset with potential applications in oncology, gene therapy, and autoimmune disorders. VADC45 is an antibody-drug conjugate (ADC) targeting the CD45 protein, a validated target for various blood cancers. The linker-payload used in VADC45 is also clinically validated. Vor Bio is progressing with IND-enabling studies for VADC45 to facilitate future Phase 1 studies.
Next Steps
Vor Bio plans to engage with the U.S. Food & Drug Administration (FDA) to discuss a pivotal trial design for trem-cel + Mylotarg around year-end.
