Recent studies have shown that CD32/CD8a/CD28/CD3ζ chimeric receptor cells directly kill breast cancer cells, suggesting the existence of cell surface myeloid FcγR alternative ligands (ALs). Here, we investigated the metabolism, ALs, cytotoxicity, and immunoregulatory functions of CD64/CD28/CD3ζ in colorectal cancer (CRC) and squamous cell carcinoma of the head and neck.
The CD64/CD28/CD3ζ -SFG retroviral vector was used to produce viruses for T-cell transduction. T-cell expansion and differentiation were monitored via flow cytometry. Gene expression was assessed by RNA-seq. Bioenergetics were documented on a Seahorse extracellular flux analyzer. CD64/CD28/CD3ζ polarization was identified via confocal microscopy. Cytotoxicity was determined by MTT assay and bioluminescent imaging, and flow cytometry. Tridimensional antitumor activity of CD64/CD28/CD3ζ T cells was achieved by utilizing HCT116-GFP 3D spheroids via the IncuCyte S3 Live-Cell Analysis system. The intraperitoneal distribution and antitumor activity of NIR-CD64/CD28/CD3ζ and NIR-nontransduced T cells were investigated in CB17-SCID mice bearing subcutaneous FaDu Luc + cells by bioluminescent and fluorescent imaging. IFNγ was assessed by ELISA.
Compared to CD16/CD8a/CD28/CD3ζ T cells, CD32/CD8a/CD28/CD3ζ T cells, and non-transduced T cells, CD64/CD28/CD3ζ T cells exhibited the highest levels of cell expansion and persistence capacity. A total of 235 genes linked to cell division and 52 genes related to glycolysis were overexpressed. The glycolytic phenotype was confirmed by functional in vitro studies accompanied by preferential T-cell effector memory differentiation. Interestingly, oxamic acid was found to inhibit CD64-CR T cell proliferation, indicating the involvement of lactate. Upon CD64/CD28/CD3ζ T-cell conjugation with CRC cells, CD64/CD28/CD3ζ cells polarize at immunological synapses, leading to CRC cell death. CD64/CD28/CD3ζ T cells kill SCCHN cells, and in combination with the anti-B7-H3 mAb (376.96) or anti-EGFR mAb, these cells trigger antibody-dependent cellular cytotoxicity (ADCC) in vitro under 2D and 3D conditions. The 376.96 mAb combined with CD64/CD28/CD3ζ T cells had anti-SCCHN activity in vivo. In addition, they induce the upregulation of PD-L1 and HLA-DR expression in cancer cells via IFNγ. PD-L1 positive SCCHN cells in combination with anti-PD-L1 mAb and CD64-CR T cells were killed by ADCC, which enhanced direct cytotoxicity. These findings indicate that the glycolytic phenotype is involved in CD64-CR T cell proliferation/expansion. These cells mediate long-lasting HLA-independent cytotoxicity and ADCC in CRC and SCCHN cells.
CD64/CD28/CD3ζ T cells could significantly impact the rational design of personalized studies to treat CRC and SCCHN and the identification of novel FcγR ALs in cancer and healthy cells.
© 2025. The Author(s).

Abstract Background Recent studies have shown that CD32/CD8a/CD28/CD3ζ chimeric receptor cells directly kill breast cancer cells, suggesting the existence of cell surface myeloid FcγR alternative ligands (ALs). Here, we investigated the metabolism, ALs, cytotoxicity, and immunoregulatory functions of CD64/CD28/CD3ζ in colorectal cancer (CRC) and squamous cell carcinoma of the head and neck. Methods The CD64/CD28/CD3ζ -SFG retroviral vector was used to produce viruses for T-cell transduction. T-cell expansion and differentiation were monitored via flow cytometry. Gene expression was assessed by RNA-seq. Bioenergetics were documented on a Seahorse extracellular flux analyzer. CD64/CD28/CD3ζ polarization was identified via confocal microscopy. Cytotoxicity was determined by MTT assay and bioluminescent imaging. Tridimensional antitumor activity of CD64/CD28/CD3ζ T cells was achieved by utilizing HCT116-GFP 3-D spheroids via the IncuCyte S3 Live-Cell Analysis system. The intraperitoneal distribution and antitumor activity of NIR-CD64/CD28/CD3ζ and NIR-nontransduced T cells were investigated in CB17-SCID mice bearing subcutaneous FaDu Luc + cells by bioluminescent and fluorescent imaging. IFNγ was assessed by ELISA. Results Compared to CD16/CD8a/CD28/CD3ζ T cells, CD32/CD8a/CD28/CD3ζ T cells, and nontransduced T cells, CD64/CD28/CD3ζ T cells exhibited the highest levels of cell expansion and persistence capacity. A total of 235 genes linked to cell division and 52 genes related to glycolysis were overexpressed. The glycolytic phenotype was confirmed by functional in vitro studies accompanied by preferential T-cell effector memory differentiation. Upon CD64/CD28/CD3ζ T-cell conjugation with CRC cells, CD64/CD28/CD3ζ cells polarize at immunological synapses, leading to CRC cell death. CD64/CD28/CD3ζ T cells kill SCCHN cells, and in combination with the anti-B7-H3 mAb (376.96) or anti-EGFR mAb, these cells trigger ADCC in vitro under 2D and 3D conditions. The 376.96 mAb combined with CD64/CD28/CD3ζ T cells had anti-SCCHN activity in vivo. In addition, they induce the upregulation of PD-L1 and HLA-DR expression on cancer cells via IFNγ. PD-L1 upregulation resulted in the generation of ADCC, which enhanced direct cytotoxicity. These findings indicate that, despite the glycolytic phenotype, these cells mediate long-lasting HLA-independent cytotoxicity and ADCC in CRC and SCCHN cells. Conclusions CD64/CD28/CD3ζ T cells could significantly impact the rational design of personalized studies to treat CRC and HNSCC and the identification of novel FcγR ALs in cancer and healthy cells.

Humanized tumour models could be particularly valuable for cancer immunotherapy research, as they may better reflect human-specific aspects of the interfaces between tumour and immune system of human cancer. However, endogenous antitumour immunity in humanized models is still largely undefined.
We established an autologous humanized mouse tumour model by using NSG mice reconstituted with human immune cells from hematopoietic progenitors and tumours generated from transformed autologous human B cells. We demonstrate growth of solid lymphoid tumours after subcutaneous implantation, infiltration by endogenous human immune cells and immunocompetence of the model.
We found human T cell subsets described in human cancer, including progenitor exhausted (Tpex), terminally exhausted (Tex-term) and tissue-resident (TRM) cells in tumour-bearing humanized mice with accumulation of Tex-term and TRM in the tumour. In addition, we identified tumour-reactive CD8+ T cells through expression of CD137. This subpopulation of de novo arising human CD137+ CD8+ T cells displayed a highly proliferative, fully activated effector and exhausted-like phenotype with enhanced expression of activation and exhaustion markers like PD-1, CD39, CD160, TIM-3, TIGIT and TOX, the senescence marker CD57 (B3GAT1) and cytolytic effector molecules such as PRF1, GZMH and NKG7. Moreover, these CD137+ CD8+ T cells exhibited tumour-specific clonal expansion and presented signature overlap with tumour-reactive CD8+ T cells described in human cancer. We demonstrate superior anticancer activity of this activated and exhausted-like human CD8+ T cell subset by adoptive transfer experiments using recipients bearing autologous human tumours. Mice adoptively transferred with CD137+ CD8+ T cells showed reduced tumour growth and higher CD8+ T cell tumour infiltration, correlating with control of human tumours.
We established an immunocompetent humanized tumour model, providing a tool for immunotherapy research and defined effective anticancer activity of human effector CD8+ T cells with an activated and exhausted-like phenotype, supporting clinical exploration of such cells in adoptive T cell therapies.
Swiss Cancer Research foundation.
Copyright © 2024 The Author(s). Published by Elsevier B.V. All rights reserved.

CD44 has been described in many malignancies as a marker of cancer stem cells (CSCs). Several techniques can be used to detect these cells. Here we detail CD44 detection by flow cytometry, a precise technique allowing to determine the percentage of positive cells and the mean fluorescent intensity reflecting the CD44 expression by cells in the samples. The protocol explained here can be used to detect CD44 from cell suspensions prepared from tissues or in vitro cell cultures.
© 2024. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.

Background Humanized tumor models could be particularly valuable for cancer immunotherapy research, as they may better reflect human-specific aspects of the interfaces between tumor and immune system of human cancer. However, endogenous antitumor immunity in humanized models is still largely undefined. Methods We established a novel autologous humanized mouse tumor model by using NSG mice reconstituted with human immune cells from hematopoietic progenitors and tumors generated from transformed autologous human B cells. We demonstrate growth of solid lymphoid tumors after subcutaneous implantation, infiltration by endogenous human immune cells and immunocompetence of the model. Findings We found human T cell subsets described in human cancer, including progenitor exhausted (T pex ), terminally exhausted (T ex-term ) and tissue-resident (T RM ) cells in tumor-bearing humanized mice with accumulation of T ex-term and T RM in the tumor. In addition, we identified tumor-reactive CD8 + T cells through expression of CD137. This subpopulation of de novo arising human CD137 + CD8 + T cells displayed a highly proliferative, fully activated effector and exhausted-like phenotype with enhanced expression of activation and exhaustion markers like PD-1, CD39, CD160, TIM-3, TIGIT and TOX, the senescence marker CD57 ( B3GAT1 ) and cytolytic effector molecules such as PRF1 , GZMH and NKG7 . Moreover, these CD137 + CD8 + T cells exhibited tumor-specific clonal expansion and presented signature overlap with tumor-reactive CD8 + T cells described in human cancer. We demonstrate superior anticancer activity of this exhausted-like human CD8 + T cell subset by adoptive transfer experiments using recipients bearing autologous human tumors. Mice adoptively transferred with CD137 + CD8 + T cells showed reduced tumor growth and higher CD8 + T cell tumor infiltration, correlating with control of human tumors. Interpretation We established an immunocompetent humanized tumor model, providing a tool for immunotherapy research and defined effective anticancer activity of human effector CD8 + T cells with an exhausted-like phenotype, supporting clinical exploration of such cells in adoptive T cell therapies. Funding Swiss Cancer Research foundation. Research in context Evidence before this study Antitumor immune responses and outcome of immunotherapeutic interventions are not always consistent between mouse models of cancer and data available in humans. This may be due to species-specific differences, therefore models with a potential for better translatability are needed, such as humanized mouse models. However, there is limited data on human antitumor T cell immunity in humanized mice. Added value of this study In this study, we established an immunocompetent humanized tumor model that recapitulates hallmarks of human antitumor T cell responses, offering the possibility for further translational investigation of the interface between human tumors and endogenous anticancer immunity. Furthermore, using functional in vitro assays and adoptive transfer, our study demonstrates the key importance of human effector CD8 + T cells with an activated and exhausted-like phenotype in the antitumor immune response. Implications of all the available evidence The autologous humanized tumor model provided in this study can serve as a tool to elucidate human-specific immune features. By bridging a gap between syngeneic mouse tumor models and human-specific antitumor immune responses, the model may help open up avenues for greater translatability of preclinical data. Our findings suggest that exhausted-like effector CD8 + T cells can be harnessed for clinical development of adoptive T cell therapies.