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Association of DNA hypomethylating agents (DHA) with immune-checkpoint inhibitors (ICI) is a promising strategy to improve efficacy of ICI-based therapy. Here we report the five-year clinical outcome and an integrated multi-omics analysis of pre- and on-treatment lesions from advanced melanoma patients enrolled in the phase Ib NIBIT-M4 study, a dose-escalation trial of the DHA agent guadecitabine combined with ipilimumab. With a minimum follow-up of 45 months the median OS was 25.6 months; the 5-year OS rate was 28.9% and the median DoR was 20.6 months. Specific genomic features and extent of T and B cellmediated immunity discriminated lesions of responding compared to non-responding patients. Enrichment for proliferation and EMT-related gene programs, and immune escape mechanisms characterized lesions from non-responding patients. Integration of a genetic immunoediting index (GIE) with an adaptive immunity signature (ICR) stratified patients/lesions into four distinct subsets and discriminated 5-year OS and PFS. These results suggest that coupling of immunoediting with activation of adaptive immunity is a relevant requisite for achieving long term clinical benefit by epigenetic immunomodulation in advanced melanoma patients.

DNA hypomethylating agents (DHA) combined with immune-checkpoint inhibitors (ICI) is a promising strategy to improve the effect of immunotherapy. Providing initial support to this notion, the phase Ib NIBIT-M4 study, a dose-escalation trial of the DHA guadecitabine plus ipilimumab, has shown this regimen to be safe, tolerable and with promising immunomodulatory and anti-tumor activity in advanced melanoma. Here we report the 5-year clinical outcome of NIBIT-M4 patients and its correlation with an integrated multi-omic analysis. The NIBIT-M4 enrolled unresectable Stage III or IV cutaneous melanoma patients. Median Overall Survival (OS), Progression Free Survival (PFS), 5-year OS and PFS rate, and median Duration of Response (DoR) were assessed. Tumor biopsies were performed at baseline and at week 4 and 12 on-treatment. RNA-seq, whole exome sequencing (WES), RRBS methylation profiling, and tumor immune contexture data generated by immunohistochemistry (IHC), were integratively analyzed and correlated with clinical outcome. Patients were classified as responder (R) or non-responder (NR) based on Disease Control. Nineteen patients were enrolled in the NIBIT-M4 study between October 2015, and August 2018. As of July 1, 2022, median OS was 25.6 months (mo) (95% CI, 0.0-52.9), median PFS was 5.2 mo (95% CI, 4.0-6.4); 5-year OS rate was 28.9% and 5-year PFS rate was 5.3 %; median DoR was 20.6 mo (95% CI, 12.4-28.8). Tumor biopsies for correlative analyses were available from 14 patients. Compared to NR, R patients showed higher mutation frequency in NRAS, while NR patients harbored more frequent somatic alterations in genes involved in Epithelial to Mesenchymal Transition (EMT) and chromatin organization pathways. By tumor transcriptome analysis, NR patients showed enrichment for proliferation/differentiation/EMT pathways associated with suppression of INF-ɣ/HLA-II/immune-related transcriptional modules. R patients displayed a dynamic pattern of activated immune signatures related to CD8+ Tex cells, B cells, tertiary lymphoid structures, TFH cells and IFN-ɣ, reaching highest expression levels in week 12 biopsies. Deconvolution of transcriptomic data showed higher CD8+ and NK cell content and higher correlation of TCRB clonality with CD8+ content in R patients. By integration of a genetic immunoediting index (GIE) with an adaptive immunity signature (ICR) lesions were stratified into four distinct subsets. Interestingly, the ICR/GIE classification discriminated 5-year OS and PFS while the classification based on response groups did not. Moreover, patients with a “high ICR/non-GIE” (i.e., without immunoediting) showed lower expression of antigen presentation and processing-related genes associated with defective HLA-class I expression in the lesions, in spite of high CD8+ content. Citation Format: Teresa Noviello, Anna Maria Di Giacomo, Francesca Pia Caruso, Alessia Covre, Giovanni Scala, Luigi Ferraro, Sandra Coral, Wolf H. Fridman, Catherine Sautes-Fridman, Roberta Mortarini, Elena Simonetti, Maria Fortunata Lofiego, Davide Bedognetti, Andrea Anichini, Michele Ceccarelli, Michele Maio. Guadecitabine plus ipilimumab in unresectable melanoma: Five-year follow-up and correlation with integrated, multi-omic analysis in the NIBIT-M4 trial [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3273.

Background Growing evidence are demonstrating the therapeutic efficacy of immune checkpoint inhibitors (ICI) in mesothelioma; however, a limited percentage of patients benefits from this therapeutic approach. Epigenetic modifications play a relevant role in negatively regulating the cross-talk between neoplastic and immune cells, and in contributing to the highly immunosuppressive mesothelioma microenvironment. A better understanding of mesothelioma epigenetic landscape could open the path to novel and potentially more effective approaches combining ICI and epigenetic drugs. We investigated the immunomodulatory potential of epigenetic agents by comparing the activity of DNA hypomethylating agents (DHA) with histone deacetylases inhibitors (HDACi) and EZH2 inhibitors (EZH2i), alone or combined with DHA, in mesothelioma cells. Methods Four mesothelioma cell lines were treated with the DHA guadecitabine 1μM, or with the HDACi, Valproic Acid (VPA) 1mM, or the EZH2i, EPZ-6438 1μM, alone or combined with guadecitabine. We investigated the expression of HLA class I molecules by flow-cytometry and of PD-L1, cancer testis antigens (CTA: NY-ESO, MAGE-A1), Natural Killer Group 2 member D Ligands (NKG2DLs: MIC-A, MIC-B, ULBP2) and EMT-regulating cadherins (CDH1, CDH2) by quantitative Real-Time PCR. Fold change (FC) expression for each treatment vs untreated cells was reported as mean values (FCm) among investigated cell lines. A positive modulation of the expression was considered if FCm>1.5. Results Guadecitabine upregulated the expression of HLA class I antigens (FCm=1.75), PD-L1 (FCm=2.38), NKG2DLs (MIC-A FCm=1.96, MIC-B FCm=2.57, and ULBP2 FCm=3.56), and upregulated/induced CTA expression. Similarly, VPA upregulated HLA class I antigens (FCm=1.67), PD-L1 (FCm=3.17), NKG2DLs (MIC-A FCm=1.78, MIC-B FCm=3.04, and ULBP2 FCm=3.75) expression; however, CTA expression was modulated only in 1 mesothelioma cell line. Conversely, EPZ-6438 up-regulated only NY-ESO-1 and MIC-B expression in 1 mesothelioma cell line. The addition of both VPA and EPZ-6483 to guadecitabine strengthened its immunomodulatory activity. Specifically, guadecitabine plus VPA or EPZ-6438 upregulated the expression of HLA class I antigens FCm=2.55 or 2.69, PD-L1 FCm=8.04 or 2.65, MIC-A FCm=3.81 or 2.26, MIC-B FCm=8.00 or 3.03, ULBP2 FCm=6.24 or 4.53, respectively. Higher levels of CTA upregulation/induction were observed with combination treatments vs guadecitabine alone. Cadherins modulation was mesothelioma histotype-related: CDH1 expression was induced in the 2 constitutively-negative sarcomatoid mesothelioma cells by guadecitabine alone or combined with VPA or EPZ-6438; CDH2 expression was upregulated by VPA alone (FCm=1.53) or plus guadecitabine (FCm=2.54). Conclusions Combination of DHA-based immunotherapies with other classes of epigenetic drugs could be an effective strategy to be pursued in the mesothelioma clinic.

Until very few years ago, the oncology community dogmatically excluded any clinical potential for immunotherapy in controlling brain metastases. Therefore, despite the significant therapeutic efficacy of monoclonal antibodies to immune check-point(s) across a wide range of tumor types, patients with brain disease were invariably excluded from clinical trials with these agents. Recent insights on the immune landscape of the central nervous system, as well as of the brain tumor microenvironment, are shedding light on the immune-biology of brain metastases. Interestingly, retrospective analyses, case series, and initial prospective clinical trials have recently investigated the role of different immune check-point inhibitors in brain metastases, reporting a significant clinical activity also in this subset of patients. These findings, and their swift translation in the daily practice, are driving fundamental changes in the clinical management of patients with brain metastases, and raise important neuroradiologic challenges. Along this line, neuro-oncology undoubtedly represents an additional area of active investigation and of growing interest to support medical oncologists in the evaluation of clinical responses of brain metastases to ICI treatment, and in the management of neurologic immune-related adverse events. Aim of this review is to summarize the most recent findings on brain metastases immunobiology, on the evolving scenario of clinical efficacy of ICI therapy in patients with brain metastases, as well as on the increasing relevance of neuroradiology in this therapeutic setting.

Rationale: Glioblastoma multiforme (GBM) is the most common and deadliest primary brain tumour in adults, with a very dismal prognosis and limited effective therapies. Immunotherapy may play a role in treating GBM, though the initial clinical results are still poor, and novel combined treatment(s) could possibly improve its efficacy. Manipulating the epigenome has been considered a therapeutic opportunity in GBM, since epigenetic modifications regulate glioma proliferation, metastasis, invasion, and prognosis. In addition, epigenetic alterations may negatively regulate the cross-talk between GBM and immune cells in GBM microenvironment (TME), thus limiting the efficacy of immunotherapy. We previously demonstrated the immunomodulatory potential of epigenetic drugs in cancer cells, and translated this notion in the clinic to improve efficacy of immunotherapy of melanoma patients (Di Giacomo AM, CCR 2019). Accordingly, this study aimed to evaluate the immunomodulatory potential of epigenetic drugs in GBM, and to provide the scientific rationale for new combinatorial therapeutic approaches in GBM patients. Methods: Patient-derived GBM (pGBM) cell lines (n=10) were established from surgically-removed GBM lesions and treated with the DNA hypomethylating agent guadecitabine (1 µM); commercially available human GBM (cGBM) cell lines (n=3) were treated with guadecitabine (1 µM) and/or with the EZH2-inhibitor GSK126 (10 µM). Expression of HLA class I and ICAM-1 by GBM cells was investigated by flow-cytometry; cancer testis antigens (CTA, i.e., NY-ESO, MAGE-A1 and MAGE-A3) and the epithelial-mesenchymal transition (EMT)-regulating cadherins (i.e., CDH1 and CDH2) expression was analyzed by quantitative Real-Time PCR. Results: A positive modulation of immune profile was observed in all investigated guadecitabine-treated GBM cells. Specifically, in untreated vs guadecitabine-treated cells, MFI mean values ± SD of HLA class I were 402±326 vs 442±303 in pGBM cells, and 277±127 vs 381±138 in cGBM cells; MFI mean values ± SD of ICAM-1 were 53±72 vs 92±116 in pGBM cells, and 5±6 vs 26±17 in cGBM cells. Though a slight increment was induced by GSK126 for HLA class I (312±169) and ICAM-1 (9±11) expression in cGBM, an additive effect was detected with GSK126+guadecitabine (405±261 for HLA class I and 35±22 for ICAM-1) in cGBM cells. Guadecitabine induced NY-ESO-1, MAGE-A1, and MAGE-A3 expression in 9/10, 6/10, and 5/8 pGBM cells, respectively and in all cGBM cells. Levels of CTA expression were increased in cGBM by GSK126+guadecitabine vs guadecitabine with mean Fold Change (FC) of 1.5, 1.6 and 1.6 for NY-ESO-1, MAGE-A1 and MAGE-A3 expression. Finally, CDH1 expression was induced in 1/3 and in 2/3 cGBM cells by guadecitabine and guadecitabine+GSK126, respectively; CDH2-positive expression was upregulated by guadecitabine (mean FC=2.45) but not by guadecitabine+GSK126. Conclusions: Immunomodulatory properties of epigenetic drugs in GBM should be exploited to improve the efficacy of GBM immunotherapy. Citation Format: Maria Fortunata Lofiego, Francesca Piazzini, Carolina Fazio, Ornella Cutaia, Carla Chiarucci, Sara Cannito, Elisabetta Gambale, Monica Valente, Anna Maria Di Giacomo, Sandra Coral, Clelia Miracco, Giuseppe Oliveri, Michele Maio, Alessia Covre. Immunomodulatory activity of epigenetic drugs: Laying the ground for new combined immunotherapeutic strategies for glioblastoma [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4488.

Targeting of the programmed cell death protein (PD)-1/programmed death-ligand 1 (PD-L1) axis has shown a significant clinical impact in several tumor types. Accordingly, our phase II NIBIT-MESO-1 study demonstrated an improved clinical efficacy in mesothelioma patients treated with the anti-PD-L1 durvalumab combined with the anti-cytotoxic T-lymphocyte antigen (CTLA)-4 tremelimumab, as compared to tremelimumab alone. Due to the promising therapeutic activity of immune check-point inhibitors (ICIs) in mesothelioma patients, the identification of biomarkers predictive of response to treatment is of crucial relevance. The prognostic role of soluble PD-L1 (sPD-L1) proposed in cancer patients prompted us to investigate this protein in sera from mesothelioma patients (n = 40) enrolled in the NIBIT-MESO-1 study. A significant (p &lt, 0.001) increase in sPD-L1 levels was detected in patients after the first cycle and during therapy vs. baseline. A longer overall survival (OS) was observed in patients with sPD-L1 concentrations below (at baseline, d1C2, d1C5 (p &lt, 0.01)) or FC values above (p &lt, 0.05 at d1C2, d1C3, d1C5) their statistically calculated optimal cut-offs. On the basis of these initial results, the specific role of CTLA-4-, PD-L1-, or PD-1-targeting on sPD-L1 release was then investigated in sera from 81 additional ICI-treated solid cancer patients. Results showed a significant (p &lt, 0.001) increase of sPD-L1 levels during therapy compared to baseline only in anti-PD-L1-treated patients, supporting the specific involvement of PD-L1 targeting in the release of its soluble form. Our findings suggest that sPD-L1 represents a predictive biomarker of clinical response to anti-PD-L1 cancer immunotherapy.

DNA hypomethylating agents (DHAs) play a well-acknowledged role in potentiating the immunogenicity and the immune recognition of neoplastic cells. This immunomodulatory activity of DHAs is linked to their ability to induce or to up-regulate on neoplastic cells the expression of a variety of immune molecules that play a crucial role in host-tumor immune interactions. To further investigate the clinical potential of diverse epigenetic compounds when combined with immunotherapeutic strategies, we have now compared the tumor immunomodulatory properties of the first generation DHAs, azacytidine (AZA) and decitabine (DAC) and of the next generation DHA, guadecitabine. To this end, human melanoma and hematological cancer cells were treated in vitro with 1 μM guadecitabine, DAC or AZA and then studied by molecular and flow cytometry analyses for changes in their baseline expression of selected immune molecules involved in different mechanism(s) of immune recognition. Results demonstrated a stronger DNA hypomethylating activity of guadecitabine and DAC, compared to AZA that associated with stronger immunomodulatory activities. Indeed, the mRNA expression of cancer testis antigens, immune-checkpoint blocking molecules, immunostimulatory cytokines, involved in NK and T cell signaling and recruiting, and of genes involved in interferon pathway was higher after guadecitabine and DAC compared to AZA treatment. Moreover, a stronger up-regulation of the constitutive expression of HLA class I antigens and of Intercellular Adhesion Molecule-1 was observed with guadecitabine and DAC compared to AZA. Guadecitabine and DAC seem to represent the optimal combination partners to improve the therapeutic efficacy of immunotherapeutic agents in combination/sequencing clinical studies.

Immune checkpoint(s) blockade is becoming the therapeutic mainstay in melanoma and lung cancer. Based on these important clinical achievements, immunotherapy with immunomodulating monoclonal antibodies (mAb) is being explored as a new therapeutic modality in most human malignancies, either alone or in combination with other immunomodulating agents. We have provided extensive evidence that the second generation DNA hypomethylating agent (DHA), guadecitabine (SGI-110), plays a promising role in potentiating the immunogenicity and the immune recognition of human malignancies through the up-regulation of the expression of different immune molecules on cancer cells. These findings led us to hypothesize that DHA could represent ideal partners for immune checkpoint(s) blocking agents to improve their therapeutic efficacy. Here, we studied the expression of programmed death 1 (PD-1), programmed death-ligand 1 (PD-L1), and 2 (PD-L2), and cytotoxic T lymphocyte-associated antigen 4 (CTLA4) in peripheral blood mononuclear cells of acute myeloid leukemia (AML) patients (N = 23), enrolled in a phase 1-2 study with guadecitabine. Patients included in this preliminary analysis were selected based on their responsiveness to therapy. Quantitative RT-PCR analyses showed a constitutive expression (gene/β-actin molecules >7.5E-05) of PD1, PD-L1, PD-L2 and CTLA-4 in 82.6%, 100%, 47.8% and 8.7% patients, respectively. Guadecitabine therapy up-regulated (≥2 fold) the expression of PD1, PD-L1, PD-L2 and CTLA-4 in 57.9%, 56.5%, 18.2% and 0% patients, respectively, at any of the time-points investigated during treatment. De novo expression of PD1, PD-L2 and CTLA-4 was observed in 100%, 41.6% and 38.1% of the immune checkpoint(s)-negative patients, respectively. Though preliminary, these results further support the strong link between epigenetics/DNA methylation and immune response, in cancer patients, and strengthen the therapeutic potential of epigenetic immunomodulation, with “consolidated” and emerging immune checkpoint(s) blocking mAb. Citation Format: Carolina Fazio, Alessia Covre, Maria Lofiego, Pietro Taverna, Mohammad Azab, James N. Lowder, Sandra Coral, Michele Maio. Immune checkpoint(s) expression in AML patients enrolled in a phase 1-2 study with guadecitabine. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2325.