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Updated: Jul 5, 2025
A Real-time Potency Assay for Chimeric Antigen Receptor T Cells Targeting Solid and Hematological Cancer Cells
Published on: November 12, 2019
Dual-targeting CD33/CD123 NANOBODY T-cell engager with potent anti-AML activity and good safety profile
Zhihong Zeng1, Annelies Roobrouck2, Geert Deschamps2
1Department of Leukemia, The University of Texas MD Anderson Cancer Center, Houston, TX.
Abstract:
Novel therapies are needed for effective treatment of acute myeloid leukemia (AML). Relapse is common and salvage treatment with cytotoxic chemotherapy is rarely curative. CD123 and CD33, 2 clinically validated targets in AML, are jointly expressed on blasts and leukemic stem cells in >95% of patients with AML. However, their expression is heterogenous between subclones and between patients, which may affect the efficacy of single-targeting agents in certain patient populations. We present here a dual-targeting CD33/CD123 NANOBODY T-cell engager (CD33/CD123-TCE) that was designed to decrease the risk of relapse from possible single antigen-negative clones and to increase coverage within and across patients. CD33/CD123-TCE killed AML tumor cells expressing 1 or both antigens in vitro. Compared with single-targeting control compounds, CD33/CD123-TCE conferred equal or better ex vivo killing of AML blasts in most primary AML samples tested, suggesting a broader effectiveness across patients. In a disseminated cell-line-derived xenograft mouse model of AML, CD33/CD123-TCE cleared cancer cells in long bones and in soft tissues. As cytokine release syndrome is a well-documented adverse effect of TCE, the compound was tested in a cytokine release assay and shown to induce less cytokines compared to a CD123 single-targeting control. In an exploratory single-dose nonhuman primate study, CD33/CD123-TCE revealed a favorable PK profile. Depletion of CD123 and CD33 expressing cells was observed, but there were neither signs of cytokine release syndrome nor clinical signs of toxicity. Taken together, the CD33/CD123 dual-targeting NANOBODY TCE exhibits potent and safe anti-AML activity and promises a broad patient coverage.
Insights
A novel dual-targeting NANOBODY T-cell engager (CD33/CD123-TCE) shows potent activity against acute myeloid leukemia (AML) by targeting both CD33 and CD123 antigens. This new therapy demonstrated broad patient coverage and a favorable safety profile in preclinical studies.
Area of Science:
- Hematology
- Immunology
- Oncology
Background:
- Acute myeloid leukemia (AML) treatment faces challenges with high relapse rates and limited efficacy of current salvage therapies.
- CD123 and CD33 are validated AML targets, but their heterogeneous expression necessitates broader targeting strategies.
- Single-targeting agents may be less effective due to antigen escape or variability between patient subclones.
Purpose of the Study:
- To develop and evaluate a novel dual-targeting NANOBODY T-cell engager (CD33/CD123-TCE) for enhanced AML treatment.
- To assess the efficacy and safety of CD33/CD123-TCE in preclinical AML models.
- To investigate the potential of CD33/CD123-TCE for broader patient coverage compared to single-targeting agents.
Main Methods:
- Design and in vitro testing of a dual-targeting CD33/CD123 NANOBODY T-cell engager (CD33/CD123-TCE).
- Evaluation of ex vivo killing of primary AML blasts and AML cell-line-derived xenograft mouse models.
- Assessment of cytokine release and safety profile in nonhuman primate studies.
Main Results:
- CD33/CD123-TCE demonstrated potent in vitro killing of AML cells expressing CD33 and/or CD123.
- Ex vivo studies showed equal or superior AML blast killing compared to single-targeting controls across most primary samples.
- In vivo studies showed clearance of AML cells, reduced cytokine release compared to single-target controls, and a favorable safety profile in nonhuman primates.
Conclusions:
- The dual-targeting CD33/CD123 NANOBODY T-cell engager exhibits potent and safe anti-AML activity.
- This novel therapeutic approach shows promise for broader patient coverage and overcoming relapse associated with antigen heterogeneity.
- CD33/CD123-TCE represents a promising novel therapy for acute myeloid leukemia.
