Manganese improves anti-PD-L1 immunotherapy via eliciting type I interferon signaling in melanoma.

The immune checkpoint inhibitor therapy represented by blocking programmed cell death protein 1/ programmed cell death-ligand 1 (PD-1/PD-L1) has made significant progress in melanoma treatment. However, the response rate and therapeutic effect of immunotherapy alone are still not ideal for melanoma. In this study, we aimed to evaluate the defects of treating anti-PD-L1 alone and the therapeutic effect and molecular mechanism of combined therapy with anti-PD-L1 and MnCl2. We detected the changes of immune cell populations after anti-PD-L1 treatment in melanoma xenograft mouse model. Further, we evaluated the regulatory effect of MnCl2 on dendritic cells (DCs) maturation in vitro. Next, we tested the therapeutic effect and regulatory effect on the tumor microenvironment with anti-PD-L1 and MnCl2 via combining treatment with anti-PD-L1 and MnCl2. Anti-PD-L1 therapy has a certain tumor suppressive function, but the effect is not ideal. The results of flow cytometry showed that the number of CD4+ T cells and CD8+ T cells significantly increased after anti-PD-L1 treatment. However, the number of DCs remained basically unchanged after anti-PD-L1 treatment. In vitro, we confirmed that MnCl2 significantly promoted DCs maturation vis activating cGAS-STING signaling pathway. The combination of anti-PD-L1 and MnCl2 displayed the best tumor suppression effect in melanoma xenograft mouse model. In tumor microenvironment, the infiltration of T cells and the maturation of DCs were significantly promoted, demonstrating a strong anti-tumor immune response. In summary, we conclude that combining anti-PD-L1 with MnCl2 is a promising therapeutic strategy for melanoma.

Zhang X ，Deng J ，Wu R ，Hu J ... -  《-》

FAP-targeted radioligand therapy with (68)Ga/(177)Lu-DOTA-2P(FAPI)(2) enhance immunogenicity and synergize with PD-L1 inhibitors for improved antitumor efficacy.

Fibroblast activation protein (FAP)-targeted radioligand therapy, with immunomodulatory effects, has shown efficacy in both preclinical and clinical studies. We recently reported on a novel dimeric FAP-targeting radiopharmaceutical, 68Ga/177Lu-DOTA-2P(FAPI)2, which demonstrated increased tumor uptake and prolonged retention in various cancers. However, further exploration is required to understand the therapeutic efficacy and underlying mechanisms of combining 68Ga/177Lu-DOTA-2P(FAPI)2 radioligand therapy with PD-1/PD-L1 immunotherapy. Regarding the change in PD-L1 expression and DNA double-strand breaks induced by radiopharmaceuticals, CT26-FAP tumor cells were incubated with 68Ga and 177Lu labeled DOTA-2P(FAPI)2, respectively. Monotherapy with 68Ga-DOTA-2P(FAPI)2, 177Lu-DOTA-2P(FAPI)2, and PD-L1 immunotherapy as well as combination therapy (68Ga/177Lu-DOTA-2P(FAPI)2 and PD-L1 immunotherapy) were tested and evaluated to evaluate in vivo antitumor efficacy. Furthermore, immunohistochemical staining and single-cell RNA sequencing were used to analyze changes in the tumor microenvironment (TME) and elucidate the underlying mechanisms of action of this combination therapy. Our findings indicated that FAP-targeting radiopharmaceuticals can induce DNA double-strand breaks and upregulate PD-L1 expression, with 177Lu-DOTA-2P(FAPI)2 proving to be more effective than 68Ga-DOTA-2P(FAPI)2. Both 68Ga-DOTA-2P(FAPI)2 and 177Lu-DOTA-2P(FAPI)2 radiopharmaceuticals significantly improved therapeutic outcomes when combined with anti-PD-L1 monoclonal antibody (αPD-L1 mAb). Notably, the combination of 177Lu-DOTA-2P(FAPI)2 with αPD-L1 mAb immunotherapy eliminated tumors in mouse models. Mice treated with this regimen not only exhibited exceptional responses to the initial immune checkpoint inhibitor therapy but also showed 100% tumor rejection on subsequent tumor cell re-inoculation. Further mechanistic studies have shown that 177Lu-DOTA-2P(FAPI)2 combined with αPD-L1 mAb can reprogram the TME, enhancing antitumor intercellular communication, which activates antitumor-related intercellular contacts such as FasL-Fas interactions between T cells and NK cells with tumor cells and increasing the proportion of infiltrating CD8+ T-cells while reducing regulatory T cells and inhibiting tumor progression. Our research also demonstrates that mature neutrophils play a role in enhancing the efficacy of the combined therapy, as shown in neutrophil-blocking experiments. Our study robustly advocates for use of FAP-targeting radiopharmaceuticals, particularly 177Lu-DOTA-2P(FAPI)2, alongside immunotherapy in treating FAP-positive tumors. This combination therapy transforms the TME and enables a translatable approach to increasing the sensitivity to PD-1/PD-L1 immunotherapy, leading to improved complete remission rates and extended overall survival.

Chen J ，Zhou Y ，Pang Y ，Fu K ，Luo Q ，Sun L ，Wu H ，Lin Q ，Su G ，Chen X ，Zhao L ，Chen H ... -  《Journal for ImmunoTherapy of Cancer》

INHBA promotes tumor growth and induces resistance to PD-L1 blockade by suppressing IFN-γ signaling.

Inhibin beta A (INHBA) and its homodimer activin A have pleiotropic effects on modulation of immune responses and tumor progression, but it remains uncertain whether tumors may release activin A to regulate anti-tumor immunity. In this study we investigated the effects and mechanisms of tumor intrinsic INHBA on carcinogenesis, tumor immunity and PD-L1 blockade. Bioinformatic analysis on the TCGA database revealed that INHBA expression levels were elevated in 33 cancer types, including breast cancer (BRCA) and colon adenocarcinoma (COAD). In addition, survival analysis also corroborated that INHBA expression was negatively correlated with the prognosis of many types of cancer patients. We demonstrated that gain or loss function of Inhba did not alter in vitro growth of colorectal cancer CT26 cells, but had striking impact on mouse tumor models including CT26, MC38, B16 and 4T1 models. By using the TIMER 2.0 tool, we figured out that in most cancer types, Inhba expression in tumors was inversely associated with the infiltration of CD4+ T and CD8+ T cells. In CT26 tumor-bearing mice, overexpression of tumor INHBA eliminated the anti-tumor effect of the PD-L1 antibody atezolizumab, whereas INHBA deficiency enhanced the efficacy of atezolizumab. We revealed that tumor INHBA significantly downregulated the interferon-γ (IFN-γ) signaling pathway. Tumor INHBA overexpression led to lower expression of PD-L1 induced by IFN-γ, resulting in poor responsiveness to anti-PD-L1 treatment. On the other hand, decreased secretion of IFN-γ-stimulated chemokines, including C-X-C motif chemokine 9 (CXCL9) and 10 (CXCL10), impaired the infiltration of effector T cells into the tumor microenvironment (TME). Furthermore, the activin A-specific antibody garetosmab improved anti-tumor immunity and its combination with the anti-PD-L1 antibody atezolizumab showed a superior therapeutic effect to monotherapy with garetosmab or atezolizumab. We demonstrate that INHBA and activin A are involved in anti-tumor immunity by inhibiting the IFN-γ signaling pathway, which can be considered as potential targets to improve the responsive rate of PD-1/PD-L1 blockade.

Li FL ，Gu LH ，Tong YL ，Chen RQ ，Chen SY ，Yu XL ，Liu N ，Lu JL ，Si Y ，Sun JH ，Chen J ，Long YR ，Gong LK ... -  《-》

Spatial proteomics reveals sirtuin 1 to be a determinant of T-cell infiltration in human melanoma.

The tumour microenvironment significantly influences the clinical response of patients to therapeutic immune checkpoint inhibition (ICI), but a comprehensive understanding of the underlying immune-regulatory proteome is still lacking. To decipher targetable biologic processes that determine tumour-infiltrating lymphocytes (TiLs) as a cellular equivalent of clinical response to ICI. We mapped the spatial distribution of proteins in TiL-enriched vs. TiL-low compartments in melanoma by combining microscopy, matrix-assisted laser desorption mass spectrometry imaging and liquid chromatography-mass spectrometry, as well as computational data mining. Pharmacological modulation of sirtuin 1 (SIRT1) activity in syngeneic mouse models was used to evaluate the efficacy of pharmacological SIRT1 activation in two syngeneic melanoma mouse models, one known to be α-programmed cell death protein 1 (PD-1) sensitive and the other α-PD-1 resistant. Spatial proteomics and gene ontology-based enrichment analysis identified > 145 proteins enriched in CD8high tumour compartments, including negative regulators of mammalian target of rapamycin signalling such as SIRT1. Multiplexed immunohistochemistry confirmed that SIRT1 protein was expressed more in CD8high than in CD8low compartments. Further analysis of bulk and single-cell RNA sequencing data from melanoma tissue samples suggested the expression of SIRT1 by different lymphocyte subpopulations (CD8+ T cells, CD4+ T cells and B cells). Furthermore, we showed in vivo that pharmacological SIRT1 activation increased the immunological effect of α-PD-1 ICI against melanoma cells in mice, which was accompanied by an increase in T-cell infiltration and T-cell-related cytokines, including interferon (IFN)-γ, CCL4, CXCL9, CXCL10 and tumour necrosis factor-α. In silico analysis of large transcriptional data cohorts showed that SIRT1 was positively associated with the proinflammatory T-cell chemokines CXCL9, CXCL10 and IFN-γ, and prolonged overall survival of patients with melanoma. Our study deciphers the proteomics landscape in human melanoma, providing important information on the tumour microenvironment and identifying SIRT1 as having important prognostic and therapeutic implications.

Placke JM ，Bottek J ，Váraljai R ，Shannan B ，Scharfenberg S ，Krisp C ，Spangenberg P ，Soun C ，Siemes D ，Borgards L ，Hoffmann F ，Zhao F ，Paschen A ，Schlueter H ，von Eggeling F ，Helfrich I ，Rambow F ，Ugurel S ，Tasdogan A ，Schadendorf D ，Engel DR ，Roesch A ... -  《-》

The ERK inhibitor LY3214996 augments anti-PD-1 immunotherapy in preclinical mouse models of BRAFV600E melanoma brain metastasis.

de Sauvage MA ，Torrini C ，Nieblas-Bedolla E ，Summers EJ ，Sullivan E ，Zhang BS ，Batchelor E ，Marion B ，Yamazawa E ，Markson SC ，Wakimoto H ，Nayyar N ，Brastianos PK ... -  《-》