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Targeting macrophage Syk enhances responses to immune checkpoint blockade and radiotherapy in high-risk neuroblastoma: TAM SYK WT/KO Adoptive Transfer Experiment

ABSTRACT: Neuroblastoma (NB) is considered an immunologically cold tumor and is usually less responsive to immune checkpoint blockade (ICB). Tumor-associated macrophages (TAMs) are highly infiltrated in NB tumors and promote immune escape and resistance to ICB. Hence therapeutic strategies targeting immunosuppressive TAMs can improve responses to ICB in NB. We recently discovered that spleen tyrosine kinase (Syk) reprograms TAMs toward an immunostimulatory phenotype and enhances T-cell responses in the lung adenocarcinoma model. Here we investigated if Syk is an immune-oncology target in NB and tested whether a novel immunotherapeutic approach utilizing Syk inhibitor together with radiation and ICB could provide a durable antitumor immune response in an MYCN amplified murine model of NB. Myeloid Syk KO mice and syngeneic MYCN-amplified cell lines were used to elucidate the effect of myeloid Syk on the NB tumor microenvironment (TME). In addition, the effect of Syk inhibitor, R788, on anti-tumor immunity alone or combination with anti-PDL1 mAb and radiation was also determined in murine NB models. The underlying mechanism of action of this novel therapeutic combination was also investigated. Herein, we report that Syk is a marker of NB -associated macrophages and plays a crucial role in promoting immunosuppression in the NB TME. We found that the blockade of Syk in NB-bearing mice markedly impairs tumor growth. This effect is facilitated by macrophages that become immunogenic in the absence of Syk, skewing the suppressive TME towards immunostimulation and activating anti-tumor immune responses. Moreover, combining FDA-approved Syk inhibitor, R788 (fostamatinib) along with anti-PDL1 mAb provides a synergistic effect leading to complete tumor regression and durable anti-tumor immunity in mice bearing small tumors (50 mm3) but not larger tumors (250 mm3). However, combining radiation to R788 and anti-PDL1 mAb prolongs the survival of mice bearing large NB9464 tumors.

ORGANISM(S): Mus musculus

PROVIDER: GSE224021 | GEO | 2023/06/02

REPOSITORIES: GEO

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Project description:Neuroblastoma (NB) is considered an immunologically cold tumor and is usually less responsive to immune checkpoint blockade (ICB). Tumor-associated macrophages (TAMs) are highly infiltrated in NB tumors and promote immune escape and resistance to ICB. Hence therapeutic strategies targeting immunosuppressive TAMs can improve responses to ICB in NB. We recently discovered that spleen tyrosine kinase (Syk) reprograms TAMs toward an immunostimulatory phenotype and enhances T-cell responses in the lung adenocarcinoma model. Here we investigated if Syk is an immune-oncology target in NB and tested whether a novel immunotherapeutic approach utilizing Syk inhibitor together with radiation and ICB could provide a durable antitumor immune response in an MYCN amplified murine model of NB. Myeloid Syk KO mice and syngeneic MYCN-amplified cell lines were used to elucidate the effect of myeloid Syk on the NB tumor microenvironment (TME). In addition, the effect of Syk inhibitor, R788, on anti-tumor immunity alone or combination with anti-PDL1 mAb and radiation was also determined in murine NB models. The underlying mechanism of action of this novel therapeutic combination was also investigated. Herein, we report that Syk is a marker of NB -associated macrophages and plays a crucial role in promoting immunosuppression in the NB TME. We found that the blockade of Syk in NB-bearing mice markedly impairs tumor growth. This effect is facilitated by macrophages that become immunogenic in the absence of Syk, skewing the suppressive TME towards immunostimulation and activating anti-tumor immune responses. Moreover, combining FDA-approved Syk inhibitor, R788 (fostamatinib) along with anti-PDL1 mAb provides a synergistic effect leading to complete tumor regression and durable anti-tumor immunity in mice bearing small tumors (50 mm3) but not larger tumors (250 mm3). However, combining radiation to R788 and anti-PDL1 mAb prolongs the survival of mice bearing large NB9464 tumors.

Project description:Tumor-associated macrophages (TAMs), often adopting an immunosuppressive M2-like phenotype, correlate with unfavorable cancer outcomes. Our investigation unveiled elevated expression of the butyrophilin (BTN)2A1 in M2-like TAMs across diverse cancer types. We developed anti-BTN2A1 monoclonal antibodies (mAb) and notably, one clone demonstrated a robust inhibitory effect on M2-like macrophage differentiation, inducing a shift towards an M1-like phenotype both in vitro and ex vivo in TAMs from patients with cancer. Macrophages treated with this anti-BTN2A1 mAb exhibited enhanced support for T-cell proliferation and IFNγ secretion. Indeed, M1-like and M2-like macrophage differentiation involves complex signaling pathways leading to specific gene expression profiles. Typically, stimuli from the TME induce pathways including JAK/STATs, MAPK, PI3K/AKT, NOTCH and NF-κB influencing TAMs polarization. We investigated the signaling pathways activated in monocytes and M-CSF-induced M2-like macrophages upon BTN2A1 engagement using anti-BTN2A mAb5. After 30 min of treatment, we observed phosphorylation of MAPKs (i.e. ERK1/2, P38 and JNK) in CD14+ monocytes and in M2-like macrophages, unlike isotype control-treated cells. In contrast, the PI3K/AKT, JAK/STAT, and NF-kB pathways were not consistently activated after 30 min of anti-BTN2A mAb5 treatment. Since BTN2A1 lacks intrinsic kinase activity, we explored whether BTN2A1 could form complexes with molecular partners in M2-like macrophages that provide kinase activity. We prepared lysates from M2-like macrophages treated with mAb5 or with its isotype control for 30 min and performed immunoprecipitation (IP) using another anti-BTN2A mAb followed by western blotting with anti-phosphoTyrosine (pTyr). A 70 kDa was co-immunoprecipitated with BTN2A1 and revealed by the anti-pTyr in lysates from anti-BTN2A mAb5-treated M2-like macrophages. To identify which Tyrosine kinase is enriched in anti-BTN2A mAb5-treated M2-like macrophages, we performed LC-MS/MS on anti-pTyr immunoprecipitates from treated cells. Several tyrosine kinases, including P38α/δ and JNK, were enriched. Notably, SYK was also identified and matched the 72kDa molecular weight of the pTyr band co-immunoprecipitated with BTN2A1.

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Targeting macrophage Syk enhances responses to immune checkpoint blockade and radiotherapy in high-risk neuroblastoma: TAM SYK WT/KO Adoptive Transfer Experiment

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