Chronic viral mimicry induction following p53 loss promotes immune evasion.

Epigenetic therapies facilitate transcription of immunogenic repetitive elements that cull cancer cells through 'viral mimicry' responses. Paradoxically, cancer-initiating events also facilitate transcription of repetitive elements. Contributions of repetitive element transcription towards cancer initiation, and the mechanisms by which cancer cells evade lethal viral mimicry responses during tumor initiation remain poorly understood.

Ratio of stemness to interferon signalling as a biomarker and therapeutic target of myeloproliferative neoplasm progression to acute myeloid leukaemia.

Progression to aggressive secondary acute myeloid leukaemia (sAML) poses a significant challenge in the management of myeloproliferative neoplasms (MPNs). Since the physiopathology of MPN is closely linked to the activation of interferon (IFN) signalling and that AML initiation and aggressiveness is driven by leukaemia stem cells (LSCs), we investigated these pathways in MPN to sAML progression. We found that high IFN signalling correlated with low LSC signalling in MPN and AML samples, while MPN progression and AML transformation were characterized by decreased IFN signalling and increased LSC signature.

Measuring the effect of drug treatments on primary human CD8+ T cell activation and cytolytic potential.

CD8+ T cells are key effector cells in adaptive immune responses against intracellular pathogens and cancer cells. Systemic drug treatments, like chemotherapy, may positively or negatively affect CD8+ T cell function. In this protocol, we describe robust and optimized polyclonal activation and cell culture conditions to measure drug treatments' effects on primary human CD8+ T cell activation and cytolytic potential.

DNA hypomethylating agents increase activation and cytolytic activity of CD8 T cells.

We demonstrate that DNA hypomethylating agent (HMA) treatment can directly modulate the anti-tumor response and effector function of CD8 T cells. In vivo HMA treatment promotes CD8 T cell tumor infiltration and suppresses tumor growth via CD8 T cell-dependent activity. Ex vivo, HMAs enhance primary human CD8 T cell activation markers, effector cytokine production, and anti-tumor cytolytic activity.

Spliceosome-Targeted Therapies Induce dsRNA Responses.

In a recent issue of Cell, Bowling et al. describe a mechanism by which spliceosome-targeted therapies result in intron-containing transcripts that form double-stranded RNAs (dsRNAs), thereby activating tumor antiviral signaling (viral mimicry) and downstream adaptive immunity.

Single-cell analysis reveals transcriptomic remodellings in distinct cell types that contribute to human prostate cancer progression.

Prostate cancer shows remarkable clinical heterogeneity, which manifests in spatial and clonal genomic diversity. By contrast, the transcriptomic heterogeneity of prostate tumours is poorly understood. Here we have profiled the transcriptomes of 36,424 single cells from 13 prostate tumours and identified the epithelial cells underlying disease aggressiveness.

Epigenetic therapy induces transcription of inverted SINEs and ADAR1 dependency.

Cancer therapies that target epigenetic repressors can mediate their effects by activating retroelements within the human genome. Retroelement transcripts can form double-stranded RNA (dsRNA) that activates the MDA5 pattern recognition receptor. This state of viral mimicry leads to loss of cancer cell fitness and stimulates innate and adaptive immune responses.

An open-label, phase II multicohort study of an oral hypomethylating agent CC-486 and durvalumab in advanced solid tumors.

Purpose: To evaluate whether administration of the oral DNA hypomethylating agent CC-486 enhances the poor response rate of immunologically 'cold' solid tumors to immune checkpoint inhibitor durvalumab.

Experimental Design: PD-L1/PD-1 inhibitor naïve patients with advanced microsatellite stable colorectal cancer; platinum resistant ovarian cancer; and estrogen receptor positive, HER2 negative breast cancer were enrolled in this single-institution, investigator-initiated trial. Two 28 day regimens, regimen A (CC-486 300 mg QD Days 1-14 (cycles 1-3 only) in combination with durvalumab 1500 mg intravenous day 15) and regimen B (CC-486 100 mg QD days 1-21 (cycle 1 and beyond), vitamin C 500 mg once a day continuously and durvalumab 1500 mg intravenous day 15) were investigated.

Methods to detect endogenous dsRNA induction and recognition.

Nucleic acid sensing is a central mechanism for innate immune defense against foreign molecules that culminates with an activation of interferon signaling pathways. This involves detection of molecular patterns associated with extracellular or intracellular pathogens by specialized receptors within the cell. In addition to foreign molecules, cells also sense endogenous molecules.

The Mitochondrial Transacylase, Tafazzin, Regulates for AML Stemness by Modulating Intracellular Levels of Phospholipids.

Tafazzin (TAZ) is a mitochondrial transacylase that remodels the mitochondrial cardiolipin into its mature form. Through a CRISPR screen, we identified TAZ as necessary for the growth and viability of acute myeloid leukemia (AML) cells. Genetic inhibition of TAZ reduced stemness and increased differentiation of AML cells both in vitro and in vivo.

The Cancer Epigenome: Exploiting Its Vulnerabilities for Immunotherapy.

During cancer initiation and progression, the somatic epigenome is broadly reprogrammed. This reprogramming can be a consequence of several processes, including altered transcriptional profiles and mutations. In addition, immune cells infiltrating the tumor microenvironment display a reprogrammed epigenome.

Pharmacological DNA demethylation: Implications for cancer immunotherapy.

Recent studies have demonstrated that DNA demethylation agents can mimic a viral infection by induction of dsRNAs. This viral mimicry leads to an antiviral response mediated by the cytosolic pattern recognition receptor MDA5, followed by MAVS (IPS1) activation, IRF7 nuclear translocation and upregulation of type III Interferon and interferon-stimulated genes.

DNA-Demethylating Agents Target Colorectal Cancer Cells by Inducing Viral Mimicry by Endogenous Transcripts.

DNA-demethylating agents have shown clinical anti-tumor efficacy via an unknown mechanism of action. Using a combination of experimental and bioinformatics analyses in colorectal cancer cells, we demonstrate that low-dose 5-AZA-CdR targets colorectal cancer-initiating cells (CICs) by inducing viral mimicry. This is associated with induction of dsRNAs derived at least in part from endogenous retroviral elements, activation of the MDA5/MAVS RNA recognition pathway, and downstream activation of IRF7.

B7-H4 expression by nonhematopoietic cells in the tumor microenvironment promotes antitumor immunity.

The B7 family plays a critical role in both positive and negative regulation of immune responses by engaging a variety of receptors on lymphocytes. Importantly, blocking coinhibitory molecules using antibodies specific for CTLA-4 and PD-1 enhances tumor immunity in a subset of patients. Therefore, it is critical to understand the role of different B7 family members since they may be suitable therapeutic targets.