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BackgroundTriple negative breast cancer (TNBC) is an aggressive breast cancer subtype characterized with poor prognosis and high metastatic potential. Although traditional chemotherapy, radiation, and surgical resection remain the standard treatment options for TNBC, bispecific antibody-based immunotherapy is emerging as new strategy in TNBC treatment. Here, we found that the receptor tyrosine kinase-like Orphan Receptor 1 (ROR1) was highly expressed in TNBC but minimally expressed in normal tissue. A bispecific ROR1-targeted CD3 T cell engager (TCE) was designed in IgG-based format with extended half-life.MethodThe expression of ROR1 in TNBC was detected by RT-qPCR and immunohistology analysis. The killing of ROR1/CD3 antibody on TNBC cells was determined by the in vitro cytotoxicity assay and in vivo PBMC reconstituted mouse model. The activation of ROR1/CD3 on T cells was analyzed by the flow cytometry and ELISA assay. Pharmacokinetics study of ROR1/CD3 was performed in mouse.ResultsThe ROR1/CD3 TCE triggered T cell activation and proliferation, which showed potent and specific killing to TNBC cells in ROR1-depedent manner. In vivo mouse model indicated that ROR1/CD3 TCE redirected the cytotoxic activity of T cells to lyse TNBC cells and induced significant tumor regression. Additionally, the ROR1/CD3 bispecific antibody exhibited an extended half-life in mouse, which may enable intermittent administration in clinic.ConclusionsCollectively, these results demonstrated that ROR1/CD3 TCE has a promising efficacy profile in preclinical studies, which suggested it as a possible option for the treatment of ROR1-expressing TNBC.Supplementary InformationThe online version contains supplementary material available at 10.1186/s13058-025-02005-w.

BackgroundAnti-CD19 chimeric antigen receptor T (CAR-T) cell therapy has proven effective for treating relapsed or refractory acute B cell leukemia. However, challenges such as cytokine release syndrome, T cell dysfunction, and exhaustion persist. Enhancing CAR-T cell efficacy through changing CAR internalization and recycling is a promising approach. The transmembrane domain is the easiest motif to optimize for modulating CAR internalization and recycling without introducing additional domains, and its impact on CAR internalization and recycling has not yet been thoroughly explored. In this study, we aim to enhance CAR-T cell function by focusing on the solely transmembrane domain design.MethodsUtilizing plasmid construction and lentivirus generation, we get two different transmembrane CAR-T cells [19CAR-T(1a) and 19CAR-T(8¦Á)]. Through co-culture with tumor cells, we evaluate CAR dynamic change, activation levels, exhaustion markers, mitochondrial function, and differentiation in both CAR-T cells. Furthermore, immunofluorescence microscopy analysis is performed to reveal the localization of internalized CAR molecules. RNA sequencing is used to detect the transcriptome of activated CAR-T cells. Finally, a mouse study is utilized to verify the anti-tumor efficacy of 19CAR-T(1a) cells in vivo.ResultsOur findings demonstrate that 19CAR-T(1a) has lower surface CAR expression, faster internalization, and a higher recycling rate compared to 19CAR-T(8¦Á). Internalized 19CAR(1a) co-localizes more with early and recycling endosomes, and less with lysosomes than 19CAR(8¦Á). These features result in lower activation levels, less cytokine release, and reduced exhaustion markers in 19CAR-T(1a). Furthermore, CAR-T cells with CD1a transmembrane domain also exhibit a superior anti-tumor ability and reduced exhaustion in vivo.ConclusionOverall, we demonstrate that the transmembrane domain plays a critical role in CAR-T cell function. An optimized transmembrane domain can alleviate cytokine release syndrome and reduce CAR-T cell exhaustion, providing a direction for CAR design to enhance CAR-T cell function.

Memory T cells are a highly heterogeneous collection of antigen-experienced cells that undergo dynamic adaptations upon antigen re-encounter and environmental signals. This heterogeneity hinders studies on memory T cell durability and age-related dysfunction. Using chronic Epstein-Barr virus (EBV) infection and barcode-enabled antigen tracing, we assess the influence of age on memory states at the level of single antigen-specific CD8+ T cells. In young adults (<40 years), EBV-specific CD8+ T cells recognizing different antigenic peptides assume divergent preferred differentiation phenotypes. In older adults (>65-years), antigen-specific cells show largely distinct phenotypic and transcriptomic aging trajectories. Common to many albeit not all antigen-specific populations are maintained TCR diversity, gained natural killer cell-like, innate signatures and lost stem-like features while no evidence is seen for cellular senescence or exhaustion. TCR avidity contributes to these phenotypic differences and aging-related changes. Collectively, our data uncover divergent antigen-guided aging shifts in memory T cell phenotypes, which are informative for antigen selection in optimizing vaccine design and adoptive T cell therapy. Homeostasis of memory T cells is modulated by each antigen encounter, thereby creating a heterogeneous population preventing precise tracking. Here, the authors use barcode-assisted tracing of Epstein-Barr virus-specific CD8+ memory T cells of young and older individuals to find antigen-guided, clonally divergent aging trajectories.