Related Experiment Video
Updated: Jun 16, 2026
Tailoring In Vivo Cytotoxicity Assays to Study Immunodominance in Tumor-specific CD8+ T Cell Responses
Published on: May 6, 2019
Species differences influencing the safety assessment of CD3 T-cell engagers
Taylor L Hickman1, David A Gallegos1, Shihui Zhong1
1Takeda Development Centers America, Inc., Cambridge, MA, USA.
Abstract:
Bispecific CD3 T-cell engagers (TCE) redirect endogenous T-cells to tumor cells and have demonstrated substantial clinical activity, but their mechanism of action also drives immune-mediated toxicities that are often underpredicted in nonhuman primate (NHP) studies. To investigate the biological basis of this translational gap, we performed a comparative evaluation of human and cynomolgus macaque T-cells using immunophenotyping, functional characterization with TCE, and single-cell transcriptomic profiling. Human and NHP donors showed broadly similar T-cell frequencies, subset distributions, and robust responses to polyclonal stimulation, confirming preserved intrinsic effector capacity in both species. However, across multiple CD20-, BCMA-, and GPRC5D-targeted TCE, human PBMC consistently exhibited greater cytotoxic potency and markedly elevated IFNγ production relative to NHP. Transcriptomic analyses revealed that although global TCR signaling architecture is conserved, human T-cells exhibit increased expression of some proximal signaling mediators, including LAT, PAG1, SKP1, and PI3K-family genes. These functional and molecular differences provide a mechanistic explanation for reduced pharmacologic responsiveness observed in NHP toxicology studies. While NHP studies can provide valuable insight for identifying antigen-dependent cytotoxic hazards, their limitations underscore the increasing importance of incorporating human-relevant models in nonclinical safety assessment.
Insights
Bispecific T-cell engagers show reduced efficacy in nonhuman primates due to species-specific T-cell responses. Understanding these differences is crucial for accurate preclinical safety assessment of immunotherapies.
Area of Science:
- Immunology
- Pharmacology
- Translational Science
Background:
- Bispecific T-cell engagers (TCE) are effective immunotherapies but can cause unpredictable toxicities.
- Nonhuman primate (NHP) models often underpredict these immune-mediated toxicities, creating a translational gap.
Purpose of the Study:
- To investigate the biological basis for the translational gap in TCE efficacy and toxicity between humans and NHPs.
- To compare human and cynomolgus macaque T-cell responses to TCE.
Main Methods:
- Comparative immunophenotyping and functional characterization of human and NHP T-cells.
- Single-cell transcriptomic profiling to analyze molecular differences.
- Evaluation of T-cell responses to CD20-, BCMA-, and GPRC5D-targeted TCE.
Main Results:
- Humans and NHPs have similar T-cell frequencies and distributions but differ in functional responses to TCE.
- Human peripheral blood mononuclear cells (PBMCs) demonstrated greater cytotoxic potency and higher IFNγ production than NHP PBMCs.
- Transcriptomic analysis revealed increased expression of proximal signaling mediators like LAT, PAG1, SKP1, and PI3K-family genes in human T-cells.
Conclusions:
- Functional and molecular differences in T-cells explain the reduced responsiveness observed in NHP toxicology studies.
- NHP models are valuable for identifying antigen-dependent cytotoxic hazards but have limitations.
- Incorporating human-relevant models is essential for improving nonclinical safety assessment of TCE.
