Mast cells (MCs) display phenotypic heterogeneity across tissues and disease contexts, yet their relevance in melanoma remains unclear. Here, we investigated MC phenotypic programs associated with melanoma progression using high-dimensional phenotyping of MCs co-cultured with melanoma spheroids, trajectory inference, and transcriptomic analyzes. Human melanoma tissues showed differences in MC phenotypic composition despite comparable abundance between outcome groups, with metastatic melanomas enriched for Tryptase⁺ Chymase- MCs. Melanoma exposure induced MC phenotypic remodeling, characterized by loss of lineage- and effector-associated features and increased PD-1 expression, with more pronounced changes following metastatic melanoma co-culture. Trajectory analysis was consistent with a continuum toward a PD-1⁺ Chymase- phenotype, which was detected in melanoma tissues and enriched within intratumoral regions of metastatic melanomas. Experimentally defined protein changes were used to derive two MC-associated transcriptomic signatures with opposing clinical associations, reflecting lineage- and effector-enriched versus melanoma-remodeled programs. The MC-LE signature was associated with favorable survival and interferon-responsive pathways, whereas the MC-MR signature was associated with poorer survival and tumor-associated pathways. These transcriptomic associations extended beyond melanoma across multiple TCGA cancer cohorts, and independent analysis of MCs from healthy skin, basal cell carcinoma, and melanoma showed corresponding differences in MC-LE-related features. Together, these findings support distinct mast cell phenotypic programs associated with melanoma progression and identify a PD-1⁺ Chymase- MC phenotype enriched in metastatic disease and linked to transcriptomic features of poor survival.
Introduction Although first-line immune-based combinations have reshaped the management of metastatic renal cell carcinoma (mRCC), relevant unmet clinical needs remain. Sarcomatoid feature is a negative prognostic factor that confers sensitivity to immunotherapy, yet the optimal ICI combination in this subgroup is still unclear.Methods The Meet-URO 33 is an Italian multicenter retrospective/prospective observational study enrolling patients with mRCC receiving first-line systemic therapy in routine clinical practice. In the present sub-analysis, objective response and survival outcomes were compared between ICI–ICI and ICI–TKI regimens in patients with documented sarcomatoid differentiation and IMDC intermediate-/poor-risk disease.Results Among 1695 patients enrolled from 58 centers, 180 (10.6%) had sRCC and among them, 107 (58.2%) were intermediate-risk and 56 (30.4%) were poor-risk. With a median follow-up of 21.8 months, in the I/P-sRCC population with available data (n = 155), univariable analysis showed longer overall survival (OS) with ICI–ICI compared to ICI–TKI (HR 0.58, p = 0.04). However, in propensity score-weighted analyses, point estimates slightly favored ICI–ICI, but no statistically significant differences were observed for OS, PFS, or ORR.Conclusions In this real-world analysis comparing ICI–ICI and ICI–TKI in sarcomatoid mRCC, propensity score-weighted models showed no statistically significant differences between treatment combinations on clinical outcomes. These findings highlight the relevance of baseline disease and patients characteristics in shaping treatment outcomes and confirm the effectiveness of ICI-containing combinations in the treatment of sarcomatoid mRCC.
Chimeric antigen receptor (CAR)-T cell therapy has shown limited efficacy in glioblastoma (GB), largely because of the immunosuppressive tumor microenvironment (TME). We have previously demonstrated that the ligand-based mCD70-directed construct mCAR27 specifically eliminates CD70⁺ GB cells in vitro, and induces durable tumor remission with prolonged survival in a syngeneic model of orthotopic GB. Despite the therapeutic promise of CD70 as a GB CAR-T cell target, the impact of CD70-directed CAR-T cells on the brain tumor immune landscape after target interception remains unexplored. Here, we independently confirmed a tumorigenic role for CD70 in murine GB by performing bulk RNA sequencing and in vivo experiments. Next, we applied single-cell RNA sequencing (scRNAseq) to decipher the transcriptome of GB-infiltrating immune cells in immunocompetent mice bearing CD70+ GB after intratumoral mCAR27 therapy. CAR-T cell treatment expanded adoptively transferred cells and was associated with increased endogenous Cd8⁺ T-cell infiltration, alongside a reduction in immunosuppressive populations, including Tregs and anti-inflammatory M2-like macrophages, but also subsets of dendritic and natural-killer cells. CD70 expression was detected on multiple GB-infiltrating immune subsets, notably Tregs and M2-like macrophages. Transcriptionally, mCAR27-mediated GB remission led to a coordinated downregulation of type-I interferon-stimulated genes and immunosuppressive mediators such as Arg1, Tgfbi, Cd274, Pdcd1lg2 and Lag3, coupled with upregulation of genes involved in inflammatory resolution, findings consistent with attenuation of GB-derived inflammatory stress and immunosuppression. Collectively, we showcase that CD70-directed CAR-T cell therapy remodels the post-treatment immune landscape towards resolution of inflammation and reduced immunosuppression, supporting sustained immune surveillance.
In a recent paper published in Cancer Cell, we identified subclinical cholestasis as an accessible imprint of gut dysbiosis predicting resistance to immune checkpoint blockade. Our work connects γ-glutamyl transferase, bile-acid remodeling, and MAdCAM-1 loss to compromised antitumor immunity, opening avenues for novel biomarker-guided microbiota interventions.
Membrane-associated proliferating cell nuclear antigen (mPCNA) is an attractive tumor-selective antigen for antibody–drug conjugate (ADC) development. We generated a chimeric IgG1 ADC, RC14-MMAE, to exploit three key properties of mPCNA that support its use as an efficient delivery platform. First, flow-cytometric and imaging analyses show abundant mPCNA surface expression on multiple tumor cell lines and in JIMT1 xenografts, providing accessible epitopes for binding. Second, comparative profiling against non-malignant counterparts and normal mouse tissues reveals minimal or undetectable mPCNA at the plasma membrane of healthy cells, indicating a sharp tumor–normal differential expected to limit off-tumor targeting and improve the therapeutic window. Third, live-cell internalization assays demonstrate that RC14 rapidly accumulates in LAMP1-positive lysosomes after engaging mPCNA, confirming efficient trafficking along the endolysosomal pathway required for protease-mediated cleavage of the valine–citrulline linker and release of monomethyl auristatin E (MMAE). Consistent with this target profile, RC14-MMAE exhibits potent antigen-dependent cytotoxicity in mPCNA-positive tumor models in NSG mice, favorable pharmacokinetics, sustained payload retention in serum, robust in vivo antitumor activity with limited overt toxicity, and a significantly increased fraction of F4/80⁺ tumor-infiltrating myeloid cells within dissociated tumors. These findings establish mPCNA as a functionally validated, tumor-selective internalizing target and support RC14-MMAE as a first-in-class mPCNA-directed ADC with broad translational potential.
