Spatial distribution of tumor-infiltrating T cells indicated immune response status under chemoradiotherapy plus PD-1 blockade in esophageal cancer

Characteristics of mast cell infiltration in lung adenocarcinoma and its impact on prognosis

BACKGROUND

The role of mast cells in malignancies remains unclear, and there is no clear correlation between mast cells and tumor microvessels, tumor growth, or lung adenocarcinoma (LUAD) prognosis. This study aims to explore the association between mast cell density (MCD) and intratumoral microvessel density (MVD), clinicopathological parameters, and prognosis in LUAD, by evaluating mast cell infiltration characteristics and their prognostic significance.

METHODS

This retrospective investigation involved 238 patients with LUAD undergoing complete resection. Tumor and normal lung tissue sections outside the tumor were immunohistochemically stained for MCD in the intratumoral and outside regions, respectively. CD34 polyclonal antibody was used to measure intratumoral MVD.

RESULTS

Intratumoral regions of LUAD had a higher MCD (P < 0.001) than normal lung tissue. In the intratumoral region, MCD and CD34-MVD were positively correlated (r = 0.411, P < 0.001). Intratumoral MCD correlated with sex, smoking history, tumor differentiation, pathological subtype, and tumor size. Female sex (P = 0.012), no smoking history (P = 0.002), acinar predominant type (P = 0.012), and tumor size ≤ 3 cm (P = 0.009) were associated with a higher MCD, whereas poorly differentiated (P = 0.039) and solid/micropapillary predominant types (P = 0.001) were associated with a lower MCD. Higher intratumoral MCD exhibited a marginally improved overall survival, and individuals with higher MCD infiltration ratios (intratumoral MCD/outside the MCD) had higher disease-free and overall survival rates (log-rank P < 0.001). A high MCD infiltration ratio was associated with decreased risk of tumor progression and death following complete resection.

CONCLUSION

The tumor microenvironment controls mast cell infiltration in LUAD, and patients with increased intratumoral mast cell infiltration have better prognosis.

Macrophage-coated tumor cluster aggravates hepatoma invasion and immunotherapy resistance via generating local immune deprivation

Immune checkpoint inhibitors (ICIs) represent a promising treatment for hepatocellular carcinoma (HCC) due to their capacity for abundant lymphocyte infiltration. However, some patients with HCC respond poorly to ICI therapy due to the presence of various immunosuppressive factors in the tumor microenvironment. Our research reveals that a macrophage-coated tumor cluster (MCTC) signifies a unique spatial structural organization in HCC correlating with diminished recurrence-free survival and overall survival in a total of 572 HCC cases from 3 internal cohorts and 2 independent external validation cohorts. Mechanistically, tumor-derived macrophage-associated lectin Mac-2 binding protein (M2BP) induces MCTC formation and traps immunocompetent cells at the edge of MCTCs to induce intratumoral cytotoxic T cell exclusion and local immune deprivation. Blocking M2BP with a Mac-2 antagonist might provide an effective approach to prevent MCTC formation, enhance T cell infiltration, and thereby improve the efficacy of ICI therapy in HCC.

Efficacy and biomarker analysis of second-line nab-paclitaxel plus sintilimab in patients with advanced biliary tract cancer

Biliary tract cancer (BTC) is a highly aggressive malignancy with limited second-line therapy. We conducted this phase 2 trial to evaluate the efficacy and safety of second-line nab-paclitaxel plus sintilimab in advanced BTC. Histologically confirmed advanced BTC patients with documented disease progression after first-line chemotherapy were enrolled. Subjects received nab-paclitaxel 125 mg/m2 on days 1 and 8 plus sintilimab 200 mg on day 1, administered every 3 weeks. The primary end point was the objective response rate (ORR). The secondary end points were progression-free survival (PFS), overall survival (OS), and adverse reactions. Simultaneously, next-generation sequencing, programmed cell death ligand 1 immunohistochemistry and multiplex immunofluorescence of tumor-infiltrating lymphocytes were applied to explore potential biomarkers. Twenty-six subjects were consecutively enrolled. The ORR was 26.9% (7/26), including two complete responses and five partial responses, which met the primary end point. The disease control rate was 61.5% (16/26). The median PFS was 169 days (about 5.6 months, 95% confidence interval [CI] 60-278 days). The median OS was 442 days (about 14.7 months, 95% CI 298-586 days). Grade 3 treatment-related adverse events (TRAEs) were mainly anemia (27%), leukopenia (23%), neutropenia (19%), and peripheral sensory neuropathy (8%). No grade 4 or 5 TRAEs occurred. Biomarker analysis suggested that positive PD-L1 and high proportions of CD8+ T-cell infiltration were correlated with improved clinical outcome. Nab-paclitaxel plus sintilimab is a potentially effective and tolerable second-line regimen for advanced BTC that deserves to be studied in large-scale trials. PD-L1 status and CD8+ T cell infiltration might be promising biomarkers for efficacy prediction.

Neoadjuvant radioimmunotherapy in pancreatic cancer enhances effector T cell infiltration and shortens their distances to tumor cells

Radiotherapy is hypothesized to have an immune-modulating effect on the tumor microenvironment (TME) of pancreatic ductal adenocarcinoma (PDAC) to sensitize it to anti-PD-1 antibody (a-PD-1) treatment. We collected paired pre- and posttreatment specimens from a clinical trial evaluating combination treatment with GVAX vaccine, a-PD-1, and stereotactic body radiation (SBRT) following chemotherapy for locally advanced PDACs (LAPC). With resected PDACs following different neoadjuvant therapies as comparisons, effector cells in PDACs were found to skew toward a more exhausted status in LAPCs following chemotherapy. The combination of GVAX/a-PD-1/SBRT drives TME to favor antitumor immune response including increased densities of GZMB+CD8+ T cells, TH1, and TH17, which are associated with longer survival, however increases immunosuppressive M2-like tumor-associated macrophages (TAMs). Adding SBRT to GVAX/a-PD-1 shortens the distances from PD-1+CD8+ T cells to tumor cells and to PD-L1+ myeloid cells, which portends prolonged survival. These findings have guided the design of next radioimmunotherapy studies by targeting M2-like TAM in PDACs.