Biology subjects

Guedan, S.

Publications and source records attributed to Guedan, S..

4 recordsLinked to original sources

bioRxiv2026

C1q from C1q+ tumor-associated myeloid cells promotes resistance to T-cell engagers and CAR T-cells and is induced by LIF and glucocorticoids

Immunotherapies, particularly T-cell engagers (TCEs) and CAR T-cells, have shown limited efficacy in solid tumors, partly due to an immunosuppressive tumor microenvironment (TME). However, the molecular mechanisms by which the TME impairs immunotherapy remain poorly understood. Here, we found that C1q generated by C1q tumor-associated myeloid cells (TAMs) plays a fundamental role in shaping the immunosuppressive TME in glioblastoma (GBM), one of the most aggressive tumors. C1q suppressed T-cell activation and impaired the activity of T-cell engagers (TCEs) and CAR T-cells. Genetic ablation of C1qa improved anti-tumor responses to TCEs and CAR T-cells. We used innovative patient-derived tumor tissue cultures (PDTTCs), which preserve an intact TME, from 19 GBM patients and identified the LIF cytokine as the main inducer of C1q. Moreover, we discovered that glucocorticoids cooperate with LIF to induce C1q. The identified C1q TAM signature overlapped with an anti-LIF gene signature, was associated with poor prognosis, and was enriched in mesenchymal GBMs with NF1 mutations. The blockade of LIF using an anti-LIF neutralizing antibody decreased the presence of C1q+ TAMs, and we found that the regulation of C1q by anti-LIF is conserved between human and mouse. Using the C1qa-/- GBM mouse model, we showed that C1q mediates the anti-tumor immune response induced by LIF blockade. Our findings identify C1q TAMs as key immunosuppressive players in GBM, impairing CAR T-cells and TCE activity, and position them as therapeutic targets to improve immunotherapy responses in this devastating disease.

cancer biology↗

bioRxiv2026

Safety profiling of CAR-T cells using an organotypic human tissue platform

CAR-T-cell-associated on-target off-tumor (OTOT) toxicity represents a major safety concern, as recognition of target antigens on healthy tissues can trigger severe and potentially life-threatening complications. Predicting OTOT toxicity remains a challenge because current preclinical models fail to capture the complexity of native human tissues. Here, we developed a human organotypic tissue platform that enables functional assessment of CAR-T-cell activity in intact human tissues across organ-specific and inflammatory contexts. Using a panel of clinically relevant CAR-T-cell products with known OTOT toxicities, we demonstrate that the platform faithfully recapitulates clinically observed tissue-specific toxicity profiles. CAR-T cells targeting EGFR, HER2, and mesothelin induced inflammatory and cytotoxic responses in healthy human lung tissue, whereas CD19 CAR-T cells remained inactive. We further show that OTOT toxicity cannot be reliably predicted from antigen abundance alone but instead results from the integration of multiple target-dependent determinants, including CAR affinity, inflammatory context, antigen accessibility, and effector-cell dose. The platform also enables quantitative assessment of inflammatory and cytotoxic responses and supports evaluation of pharmacological and CAR design-based strategies to mitigate toxicity. Together, this work establishes the first human organotypic platform for functional modeling of CAR-T-cell-associated OTOT toxicity, providing a clinically relevant framework for preclinical safety evaluation and the rational development of safer engineered cell therapies. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=167 SRC="FIGDIR/small/740527v1_ufig1.gif" ALT="Figure 1"> View larger version (38K): org.highwire.dtl.DTLVardef@12c8addorg.highwire.dtl.DTLVardef@150d392org.highwire.dtl.DTLVardef@17218f7org.highwire.dtl.DTLVardef@1c54078_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗

bioRxiv2026

Context-dependent tonic signaling shapes the performance and manufacturability of a 4-1BB- based HER2 CAR-T cell therapy

The development of clinically effective CAR-T cell therapies for solid tumors requires careful optimization of receptor design, functional fitness, and manufacturability. While advancing low-affinity HER2-targeting CAR-T cells toward clinical application, we found that the candidate with the strongest in vivo antitumor activity--comprising a CD8 hinge and transmembrane region and a 4-1BB co-stimulatory domain--exhibited measurable tonic signaling. This basal antigen-independent signaling, likely driven by high CAR surface expression, was associated with increased apoptosis and reduced ex vivo expansion under research-grade manufacturing conditions. Modification of the transmembrane domain reduced CAR surface expression but did not alleviate tonic signaling and instead impaired antitumor activity. By contrast, transient pharmacologic inhibition of CAR signaling with dasatinib rescued expansion and reduced apoptosis in small-scale research cultures. Notably, these tonic-signaling-associated defects were largely absent during large-scale, GMP-compliant manufacturing, which enabled robust CAR-T cell expansion without additional benefit from dasatinib supplementation. Together, these findings show that tonic signaling is not inherently detrimental to CAR-T cell performance and that its functional consequences are highly dependent on manufacturing context. Our study underscores the importance of evaluating CAR candidates within clinically relevant production platforms and supports the advancement of this 4-1BB-based HER2-specific CAR-T cell product toward clinical testing.

immunology↗

bioRxiv2026

In vivo CRISPR-based screen identifies ZC3H12C as a mediator of CAR-T cell dysfunction in solid tumors

CAR-T cell therapy has shown limited efficacy in solid tumors, largely due to T cell dysfunction driven by chronic antigen exposure. To uncover mediators of this dysfunction, we developed an in vivo screening platform using an ovarian xenograft tumor model in which CD28-based CAR-T cells undergo exhaustion leading to tumor escape. Transcriptomic profiling of tumor-infiltrating CAR-T cells at different stages revealed dynamic upregulation of exhaustion-associated genes. We used this data to design a focused CRISPR/Cas9 library and performed an in vivo screen. We identified 14 significantly enriched candidate genes, among which ZC3H12C emerged as the top hit. Single-cell RNA and ATAC-seq confirmed ZC3H12C expression in CAR-T cells undergoing early exhaustion in vivo. ZC3H12C disruption enhanced CAR-T cell persistence and antitumor efficacy while reducing exhaustion, across both CD28- and 4-1BB-based CARs targeting distinct antigens. These results highlight ZC3H12C as a promising target to improve CAR-T therapy in solid tumors.

immunology↗