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Background: During targeted treatment, HER2-positive breast cancers invariably lose HER2 DNA amplification. In contrast, and interestingly, HER2 proteins may be either lost or gained. To longitudinally and systematically appreciate complex/discordant changes in HER2 DNA/protein stoichiometry, HER2 DNA copy numbers and soluble blood proteins (aHER2/sHER2) were tested in parallel, non-invasively (by liquid biopsy), and in two-dimensions, hence HER2-2D., Methods: aHER2 and sHER2 were assessed by digital PCR and ELISA before and after standard-of-care treatment of advanced HER2-positive breast cancer patients (n=37) with the antibody-drug conjugate (ADC) Trastuzumab-emtansine (T-DM1)., Results: As expected, aHER2 was invariably suppressed by T-DM1, but this loss was surprisingly mirrored by sHER2 gain, sometimes of considerable entity, in most (30/37; 81%) patients. This unorthodox split in HER2 oncogenic dosage was supported by reciprocal aHER2/sHER2 kinetics in two representative cases, and an immunohistochemistry-high status despite copy-number-neutrality in 4/5 available post-T-DM1 tumor re-biopsies from sHER2-gain patients. Moreover, sHER2 was preferentially released by dying breast cancer cell lines treated in vitro by T-DM1. Finally, sHER2 gain was associated with a longer PFS than sHER2 loss (mean PFS 282 vs 133 days, 95% CI [210-354] vs [56-209], log-rank test p=0.047), particularly when cases (n=11) developing circulating HER2-bypass alterations during T-DM1 treatment were excluded (mean PFS 349 vs 139 days, 95% CI [255-444] vs [45-232], log-rank test p=0.009)., Conclusions: HER2 gain is adaptively selected in tumor tissues and recapitulated in blood by sHER2 gain. Possibly, an increased oncogenic dosage is beneficial to the tumor during anti-HER2 treatment with naked antibodies, but favorable to the host during treatment with a strongly cytotoxic ADC such as T-DM1. In the latter case, HER2-gain tumors may be kept transiently in check until alternative oncogenic drivers, revealed by liquid biopsy, bypass HER2. Whichever the interpretation, HER2-2D might help to tailor/prioritize anti-HER2 treatments, particularly ADCs active on aHER2-low/sHER2-low tumors., Trial Registration: NCT05735392 retrospectively registered on January 31, 2023 https://www., Clinicaltrials: gov/search?term=NCT05735392., (© 2024. The Author(s).)

Precision medicine has driven a major change in the treatment of many forms of cancer. The discovery that each patient is different and each tumor mass has its own characteristics has shifted the focus of basic and clinical research to the singular individual. Liquid biopsy (LB), in this sense, presents new scenarios in personalized medicine through the study of molecules, factors, and tumor biomarkers in blood such as circulating tumor cells (CTCs), circulating tumor DNA (ctDNA), exosomes and circulating tumor microRNAs (ct-miRNAs). Moreover, its easy application and complete absence of contraindications for the patient make this method applicable in a great many fields. Melanoma, given its highly heterogeneous characteristics, is a cancer form that could significantly benefit from the information linked to liquid biopsy, especially in the treatment management. In this review, we will focus our attention on the latest applications of liquid biopsy in metastatic melanoma and possible developments in the clinical setting.

Cancer stem cells (CSCs) are a subpopulation of cancer cells endowed with high tumorigenic, chemoresistant and metastatic potential. Nongenetic mechanisms of acquired resistance are increasingly being discovered, but molecular insights into the evolutionary process of CSCs are limited. Here, we show that type I interferons (IFNs-I) function as molecular hubs of resistance during immunogenic chemotherapy, triggering the epigenetic regulator demethylase 1B (KDM1B) to promote an adaptive, yet reversible, transcriptional rewiring of cancer cells towards stemness and immune escape. Accordingly, KDM1B inhibition prevents the appearance of IFN-I-induced CSCs, both in vitro and in vivo. Notably, IFN-I-induced CSCs are heterogeneous in terms of multidrug resistance, plasticity, invasiveness and immunogenicity. Moreover, in breast cancer (BC) patients receiving anthracycline-based chemotherapy, KDM1B positively correlated with CSC signatures. Our study identifies an IFN-I → KDM1B axis as a potent engine of cancer cell reprogramming, supporting KDM1B targeting as an attractive adjunctive to immunogenic drugs to prevent CSC expansion and increase the long-term benefit of therapy., (© 2022. The Author(s).)

Eosinophils are major effectors of Th2-related pathologies, frequently found infiltrating several human cancers. We recently showed that eosinophils play an essential role in anti-tumor responses mediated by immunotherapy with the 'alarmin' intereukin-33 (IL-33) in melanoma mouse models. Here, we analyzed the mechanisms by which IL-33 mediates tumor infiltration and antitumor activities of eosinophils. We show that IL-33 recruits eosinophils indirectly, via stimulation of tumor cell-derived chemokines, while it activates eosinophils directly, up-regulating CD69, the adhesion molecules ICAM-1 and CD11b/CD18, and the degranulation marker CD63. In co-culture experiments with four different tumor cell lines, IL-33-activated eosinophils established large numbers of stable cell conjugates with target tumor cells, with the polarization of eosinophil effector proteins (ECP, EPX, and granzyme-B) and CD11b/CD18 to immune synapses, resulting in efficient contact-dependent degranulation and tumor cell killing. In tumor-bearing mice, IL-33 induced substantial accumulation of degranulating eosinophils within tumor necrotic areas, indicating cytotoxic activity in vivo. Blocking of CD11b/CD18 signaling significantly reduced IL-33-activated eosinophils' binding and subsequent killing of tumor cells, indicating a crucial role for this integrin in triggering degranulation. Our findings provide novel mechanistic insights for eosinophil-mediated anti-tumoral function driven by IL-33. Treatments enabling tumor infiltration and proper activation of eosinophils may improve therapeutic response in cancer patients.

The antitumor effectiveness of cyclophosphamide (CTX) and other chemotherapeutics was shown to rely not only on direct cytotoxicity but also on immunogenic tumor cell death and systemic immunomodulatory mechanisms, including regulatory T cell (Treg) depletion, Th1 cell polarization, type I interferon (IFN) and proinflammatory cytokine production. IFN regulatory factor (IRF)-1 is a transcriptional regulator of IFNs and IFN-inducible genes, involved in the control of Th1 and Treg differentiation and in sterile inflammation. Aim of this study was to explore the role of IRF-1 in CTX-induced antitumor effects and related immune activities. This study shows for the first time that IRF-1 is important for the antitumor efficacy of CTX in mice. Moreover, experiments in tumor-bearing C57BL/6 mice showed that Irf1 gene expression in the spleen was transiently increased following CTX administration and correlated with the induction of Th1 cell expansion and of Il12p40 gene expression, which is the main Th1-driving cytokine. At the same time, CTX administration reduced both Foxp3 expression and Treg cell percentages. These effects were abrogated in Irf1 -/- mice. Further experiments showed that the gene and/or protein expression of caspase-1, iNOS, IL-1β, IL-6 and CXCL10 and the levels of nitric oxide were modulated following CTX in an IRF-1-direct- or -indirect-dependent manner, and highlighted the importance of caspase-1 in driving the sterile inflammatory response to CTX. Our data identify IRF-1 as important for the antitumor efficacy of CTX and for the regulation of many immunomodulatory activities of CTX, such as Th1 polarization, Treg depletion and inflammation., (© 2017 UICC.)

The alarmin IL-33 is an IL-1 family member that stimulates pleiotropic immune reactions depending on the target tissue and microenvironmental factors. In this study, we have investigated the role of IL-33/ST2 axis in antitumor response to melanoma. Injection of IL-33 in mice-bearing subcutaneous B16.F10 melanoma resulted in significant tumor growth delay. This effect was associated with intratumoral accumulation of CD8 + T cells and eosinophils, decrease of immunosuppressive myeloid cells, and a mixed Th1/Th2 cytokine expression pattern with local and systemic activation of CD8 + T and NK cells. Moreover, intranasal administration of IL-33 determined ST2-dependent eosinophil recruitment in the lung that prevented the onset of pulmonary metastasis after intravenous injection of melanoma cells. Accordingly, ST2-deficient mice developed pulmonary metastasis at higher extent than wild-type counterparts, associated with lower eosinophil frequencies in the lung. Of note, depletion of eosinophils by in vivo treatment with anti-Siglec-F antibody abolished the ability of IL-33 to both restrict primary tumor growth and metastasis formation. Finally, we show that IL-33 is able to activate eosinophils resulting in efficient killing of target melanoma cells, suggesting a direct antitumor activity of eosinophils following IL-33 treatment. Our results advocate for an eosinophil-mediated antitumoral function of IL-33 against melanoma, thus opening perspectives for novel cancer immunotherapy strategies.

Mesenchymal stromal cells (MSCs), first found in bone marrow (BM), are the structural architects of all organs, participating in most biological functions. MSCs possess tissue-specific signatures that allow their discrimination according to their origin and location. Among their multiple functions, MSCs closely interact with immune cells, orchestrating their activity to maintain overall homeostasis. The phenotype of tissue MSCs residing in the bowel overlaps with myofibroblasts, lining the bottom walls of intestinal crypts (pericryptal) or interspersed within intestinal submucosa (intercryptal). In Crohn's disease, intestinal MSCs are tightly stacked in a chronic inflammatory milieu, which causes their enforced expression of Class II major histocompatibility complex (MHC). The absence of Class II MHC is a hallmark for immune-modulator and tolerogenic properties of normal MSCs and, vice versa, the expression of HLA-DR is peculiar to antigen presenting cells, that is, immune-activator cells. Interferon gamma (IFN γ ) is responsible for induction of Class II MHC expression on intestinal MSCs. The reversal of myofibroblasts/MSCs from an immune-modulator to an activator phenotype in Crohn's disease results in the formation of a fibrotic tube subverting the intestinal structure. Epithelial metaplastic areas in this context can progress to dysplasia and cancer., Competing Interests: The authors declare that they have no competing interests.

Resistance to IFN-I-induced antineoplastic effects has been reported in many tumors and arises, in part, from epigenetic silencing of IFN-stimulated genes by DNA methylation. We hypothesized that restoration of IFN-stimulated genes by co-administration of the demethylating drug 5-aza-2'-deoxycitidine (decitabine [DAC]) may enhance the susceptibility to IFN-I-mediated antitumoral effects in melanoma. We show that combined administration of IFN-I and DAC significantly inhibits the growth of murine and human melanoma cells, both in vitro and in vivo. Compared with controls, DAC/IFN-I-treated melanoma cells exhibited reduced cell growth, augmented apoptosis, and diminished migration. Moreover, IFN-I and DAC synergized to suppress the growth of three-dimensional human melanoma spheroids, altering tumor architecture. These direct antitumor effects correlated with induction of the IFN-stimulated gene Mx1. In vivo, DAC/IFN-I significantly reduced melanoma growth via stimulation of adaptive immunity, promoting tumor-infiltrating CD8 + T cells while inhibiting the homing of immunosuppressive CD11b + myeloid cells and regulatory T cells. Accordingly, exposure of human melanoma cells to DAC/IFN-I induced the recruitment of immune cells toward the tumor in a Matrigel (Corning Life Sciences, Kennebunkport, ME)-based microfluidic device. Our findings underscore a beneficial effect of DAC plus IFN-I combined treatment against melanoma through both direct and immune-mediated anti-tumor effects., (Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.)

Some of the anti-neoplastic effects of anthracyclines in mice originate from the induction of innate and T cell-mediated anticancer immune responses. Here we demonstrate that anthracyclines stimulate the rapid production of type I interferons (IFNs) by malignant cells after activation of the endosomal pattern recognition receptor Toll-like receptor 3 (TLR3). By binding to IFN-α and IFN-β receptors (IFNARs) on neoplastic cells, type I IFNs trigger autocrine and paracrine circuitries that result in the release of chemokine (C-X-C motif) ligand 10 (CXCL10). Tumors lacking Tlr3 or Ifnar failed to respond to chemotherapy unless type I IFN or Cxcl10, respectively, was artificially supplied. Moreover, a type I IFN-related signature predicted clinical responses to anthracycline-based chemotherapy in several independent cohorts of patients with breast carcinoma characterized by poor prognosis. Our data suggest that anthracycline-mediated immune responses mimic those induced by viral pathogens. We surmise that such 'viral mimicry' constitutes a hallmark of successful chemotherapy.

Cyclophosphamide, within well-defined therapeutic regimens, increases the antineoplastic effects of immunotherapy. We have recently identified multiple factors and mechanisms that underlie the paradoxical synergy between these two treatment modalities. In particular, we found that cyclophosphamide stimulates anticancer immune responses upon the perception by the immune system of inflammatory danger signals associated with the death of leukocytes, via p53 and type I interferon-related mechanisms.