IL-32γ potentiates tumor immunity in melanoma
Thomas Gruber, … , Antoni Ribas, Mirjam Schenk
Thomas Gruber, … , Antoni Ribas, Mirjam Schenk
Published August 25, 2020
Citation Information: JCI Insight. 2020;5(18):e138772. https://doi.org/10.1172/jci.insight.138772.
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Research Article Immunology Oncology

IL-32γ potentiates tumor immunity in melanoma

Abstract

Myeloid cells orchestrate the antitumor immune response and influence the efficacy of immune checkpoint blockade (ICB) therapies. We and others have previously shown that IL-32 mediates DC differentiation and macrophage activation. Here, we demonstrate that IL-32 expression in human melanoma positively correlates with overall survival, response to ICB, and an immune-inflamed tumor microenvironment (TME) enriched in mature DC, M1 macrophages, and CD8+ T cells. Treatment of B16F10 murine melanomas with IL-32 increased the frequencies of activated, tumor-specific CD8+ T cells, leading to the induction of systemic tumor immunity. Our mechanistic in vivo studies revealed a potentially novel role of IL-32 in activating intratumoral DC and macrophages to act in concert to prime CD8+ T cells and recruit them into the TME through CCL5. Thereby, IL-32 treatment reduced tumor growth and rendered ICB-resistant B16F10 tumors responsive to anti–PD-1 therapy without toxicity. Furthermore, increased baseline IL-32 gene expression was associated with response to nivolumab and pembrolizumab in 2 independent cohorts of patients with melanoma, implying that IL-32 is a predictive biomarker for anti–PD-1 therapy. Collectively, this study suggests IL-32 as a potent adjuvant in immunotherapy to enhance the efficacy of ICB in patients with non–T cell–inflamed TME.

Authors

Thomas Gruber, Mirela Kremenovic, Hassan Sadozai, Nives Rombini, Lukas Baeriswyl, Fabienne Maibach, Robert L. Modlin, Michel Gilliet, Diego von Werdt, Robert E. Hunger, S. Morteza Seyed Jafari, Giulia Parisi, Gabriel Abril-Rodriguez, Antoni Ribas, Mirjam Schenk

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Figure 5

IL-32 treatment efficacy relies on the generation a proinflammatory, chemokine-rich TME.

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IL-32 treatment efficacy relies on the generation a proinflammatory, che...
(A–I) Mice bearing B16F10 tumors were treated with IL-32 or PBS as in Figure 4A. (A–C) At day 12, tumors and spleens were isolated and lysed. Cytokine and chemokine levels were assessed using multiplexed bead array (n = 10, from 2 independent experiments). Data are represented as log2(pg/mL). (A) Hierarchical clustering of cytokine protein levels in tumor lysates and (B) sera. (C) Protein expression levels of the indicated cytokines and chemokines from tumor lysates, shown as box-and-whisker plot; the box extends between 25% and 75%, and the whiskers extend to the minimum and maximum values. (D) Growth curves of IL-32– or PBS-treated primary (P = 0.2824) and (E) contralateral (P = 0.9859) B16F10 tumors inoculated in Batf3–/– mice. (F) CCL5 and (G) CCL4 expression levels in B16F10 tumors at day 12 after tumor inoculation in B6 WT and Batf3–/– mice, as determined by ELISA (PBS, n = 8; IL-32, n = 6). (H–K) IL-32– or PBS-treated B16F10 tumors in mice with or without macrophage depletion using anti-CSF1R mAb. (H) CCL5 (PBS, aCSF1R, IL-32 + aCSF1R, n = 11; IL-32, n = 10) and (I) CCL4 (PBS, aCSF1R, IL-32 + aCSF1R, n = 12; IL-32, n = 11) expression levels in B16F10 tumors at day 14 after tumor inoculation determined by ELISA. (J) Corresponding CD8+ T cell infiltration, as determined by flow cytometry (PBS, aCSF1R, IL-32 + aCSF1R, n = 12; IL-32, n = 10) and (K) tumor growth curves (PBS, aCSF1R, IL-32 + aCSF1R, n = 6; IL-32, n = 5). (L and M) CCR5–/– mice (n = 16) were inoculated with B16F10 cells. (L) At day 14, tumors were isolated and CD8+ T cell frequencies were determined by FACS. Statistical analysis was performed using 2-tailed Student’s t test. (M) Growth curves of IL-32– or PBS-treated B16F10 tumors in CCR5–/– mice (P = 0.9325). (D, E, K, and M) Tumor growth curves are depicted as mean ± SEM. Differences between groups were determined using 2-way ANOVA followed by Šidák’s multiple comparisons test. ****P < 0.0001.