Secretome of pleural effusions associated with non-small cell lung cancer (NSCLC) and malignant mesothelioma: therapeutic implications

Abstract

Introduction: We compared the secretome of metastatic (non-small cell lung cancer (NSCLC)) and primary (mesothelioma) malignant pleural effusions, benign effusions and the published plasma profile of patients receiving chimeric antigen receptor T cells (CAR-T), to determine factors unique to neoplasia in pleural effusion (PE) and those accompanying an efficacious peripheral anti-tumor immune response.

Materials and methods: Cryopreserved cell-free PE fluid from 101 NSCLC patients, 8 mesothelioma and 13 with benign PE was assayed for a panel of 40 cytokines/chemokines using the Luminex system.

Results: Profiles of benign and malignant PE were dominated by high concentrations of sIL-6Rα, CCL2/MCP1, CXCL10/IP10, IL-6, TGFβ1, CCL22/MDC, CXCL8/IL-8 and IL-10. Malignant PE contained significantly higher (p < 0.01, Bonferroni-corrected) concentrations of MIP1β, CCL22/MDC, CX3CL1/fractalkine, IFNα2, IFNγ, VEGF, IL-1α and FGF2. When grouped by function, mesothelioma PE had lower effector cytokines than NSCLC PE. Comparing NSCLC PE and published plasma levels of CAR-T recipients, both were dominated by sIL-6Rα and IL-6 but NSCLC PE had more VEGF, FGF2 and TNFα, and less IL-2, IL-4, IL-13, IL-15, MIP1α and IFNγ.

Conclusions: An immunosuppressive, wound-healing environment characterizes both benign and malignant PE. A dampened effector response (IFNα2, IFNγ, MIP1α, TNFα and TNFβ) was detected in NSCLC PE, but not mesothelioma or benign PE. The data indicate that immune effectors are present in NSCLC PE and suggest that the IL-6/sIL-6Rα axis is a central driver of the immunosuppressive, tumor-supportive pleural environment. A combination localized antibody-based immunotherapy with or without cellular therapy may be justified in this uniformly fatal condition.

Keywords: IL-6; cytokines; malignant mesothelioma; non-small cell lung cancer; pleural effusion.

Figure 1. Geometric mean cytokine levels in benign, NSCLC and mesothelioma PE.

Cytokines are ordered left to right from the highest to the lowest concentration in benign PE. Error bars indicate standard errors of the geometric means. Significant differences (p < 0.01, Bonferroni-corrected 2-tailed t-test, benign vs neoplastic) are shown with asterisks and bold-text. A dashed line is provided at 10 pg/mL for reference.

Figure 2. Geometric mean cytokine levels.

Red symbols, bold text indicates P < 0.01 Bonferroni corrected 2-tailed t-test of log analyte concentrations (see Supplementary Table 1). Diagonal line indicates equal analyte concentration in benign and malignant effusions.

Figure 3. Comparison of cytokine levels grouped by function.

Cytokine concentrations were standardized such that the geometric mean control value in the benign PE group was 0 with a standard deviation of 1 and grouped by function (Table 1).

Figure 4. Median values of 26 cytokines common to our dataset and the median one-month-peak values published as an online supplement by Teachey et al.

(2016). Cytokine Release Syndrome (CRS) grades 0–3, N = 9, CRS grades 4 and 5, N = 3. Pearson product-moment correlation coefficients (R), are shown. Diagonal line indicates equal analyte concentration in the plasma of CAR-T recipients and in malignant effusions.