Immunomodulatory Properties of DNA Hypomethylating Agents: Selecting the Optimal Epigenetic Partner for Cancer Immunotherapy

Abstract

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.

Guadecitabine Plus Ipilimumab in Unresectable Melanoma: The NIBIT-M4 Clinical Trial

“…Although the relative contributions of guadecitabine and ipilimumab to this finding cannot be unequivocally dissected, CTLA-4 blockade probably plays an active role due to its effect on T-cell function. On the other hand, upregulation of HLA class I molecules observed on melanoma cells in the majority of investigated tumor samples corroborates their established upregulation previously reported in vitro (28) and in syngeneic mouse models (18) with various DHAs, including guadecitabine (8,19).…”

“…These phenotypic changes induced or upregulated antigen-specific T-cell recognition of neoplastic cells (3)(4)(5). More recently, DHAs have also been shown to contribute to the activation of cellular immunity by modulating T helper 1-type (Th1) chemokines (6) and IFN-related genes (7,8). In addition, the DHA decitabine was also found to enhance CD8 þ T-cell activation and proliferation, and to improve the cytolytic activity of human IFN gamma þ T cells, which correlated with improved antitumor responses and survival of patients with solid tumors (9).…”

Regulatory T Cells-Related Genes Are under DNA Methylation Influence

“…For this reason, many clinical trials, which include AZA or DAC therapy, combine the therapy with CTLA-4 or PD-L1/2 inhibitors, in order to improve the outcome of the treatment [119][120][121]. Apart from AZA and DAC, another DHA-guadecitabineincreases the level of Ctla4 in melanoma and hematological cancer cells [122]. MTX also increases Ctla4 expression indirectly via its action on the Foxp3 methylation level and DNMT1 reduction.…”

<p>DNA Methyltransferase Inhibitors: Catalysts For Antitumour Immune Responses</p>

“…In a phase I dose-escalation experiment of 5-AZA-CdR in 12 patients with recurrent epithelial ovarian cancer, Odunsi et al observed increased T cell responses in most patients 111. The mRNA expression of testicular cancer antigens involved in NK and T cell signalling and recruitment, immune checkpoint blocking molecules, immunostimulatory cytokines, and genes involved in the interferon pathway was higher after treatment with guadecitabine(SGI-110) and DAC compared with the immunomodulatory effects of AZA treatment 112. In addition, this combination reduced the number of MDSCs, indicating that the immunomodulatory effects of DNMTi may be useful for immunotherapy 113.…”