Influenza Virus and SARS-CoV-2 Vaccines.

Seasonal influenza and the current COVID-19 pandemic represent looming global health challenges. Efficacious and safe vaccines remain the frontline tools for mitigating both influenza virus and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-induced diseases. This review will discuss the existing strategies for influenza vaccines and how these strategies have informed SARS-CoV-2 vaccines. It will also discuss new vaccine platforms and potential challenges for both viruses.

Role of dendritic cell metabolic reprogramming in tumor immune evasion.

The dendritic cell (DC) is recognized as a vital mediator of anti-tumor immunity. More recent studies have also demonstrated the important role of DCs in the generation of effective responses to checkpoint inhibitor immunotherapy. Metabolic programming of DCs dictates their functionality and can determine which DCs become immunostimulatory versus those that develop a tolerized phenotype capable of actively suppressing effector T-cell responses to cancers. As a result, there is great interest in understanding what mechanisms have evolved in cancers to alter these metabolic pathways, thereby allowing for their continued progression and metastasis. The therapeutic strategies developed to reverse these processes of DC tolerization in the tumor microenvironment represent promising candidates for future testing in combination immunotherapy clinical trials.

Gli2 Facilitates Tumor Immune Evasion and Immunotherapeutic Resistance by Coordinating Wnt Ligand and Prostaglandin Signaling.

Therapeutic resistance to immune checkpoint blockade has been commonly linked to the process of mesenchymal transformation (MT) and remains a prevalent obstacle across many cancer types. An improved mechanistic understanding for MT-mediated immune evasion promises to lead to more effective combination therapeutic regimens. Herein, we identify the Hedgehog transcription factor, Gli2, as a key node of tumor-mediated immune evasion and immunotherapy resistance during MT. Mechanistic studies reveal that Gli2 generates an immunotolerant tumor microenvironment through the upregulation of Wnt ligand production and increased prostaglandin synthesis. This pathway drives the recruitment, viability, and function of granulocytic myeloid-derived suppressor cells (PMN-MDSCs) while also impairing type I conventional dendritic cell, CD8 + T cell, and NK cell functionality. Pharmacologic EP2/EP4 prostaglandin receptor inhibition and Wnt ligand inhibition each reverses a subset of these effects, while preventing primary and adaptive resistance to anti-PD-1 immunotherapy, respectively. A transcriptional Gli2 signature correlates with resistance to anti-PD-1 immunotherapy in stage IV melanoma patients, providing a translational roadmap to direct combination immunotherapeutics in the clinic. SIGNIFICANCE: Gli2-induced EMT promotes immune evasion and immunotherapeutic resistance via coordinated prostaglandin and Wnt signaling.

Poor Prognosis among Radiation-Associated Bladder Cancer Is Defined by Clinicogenomic Features.

Radiotherapy (RT) for prostate cancer has been associated with an increased risk for the development of bladder cancer. We aimed to integrate clinical and genomic data to better understand the development of RT-associated bladder cancer. A retrospective analysis was performed to identify control patients (CTRL; n = 41) and patients with RT-associated bladder cancer (n = 41). RT- and CTRL-specific features were then identified through integration and analysis of the genomic sequencing data and clinical variables. RT-associated bladder tumors were significantly enriched for alterations in KDM6A and ATM, whereas CTRL tumors were enriched for CDKN2A mutation. Globally, there were an increased number of variants within RT tumors, albeit at a lower variant allele frequency. Mutational signature analysis revealed three predominate motif patterns, with similarity to SBS2/13 (APOBEC3A), SBS5 (ERCC2/smoking), and SBS6/15 (MMR). Poor prognostic factors in the RT cohort include a short tumor latency, smoking status, the presence of the smoking and X-ray therapy mutational signatures, and CDKN2A copy number loss. Based on the clinical and genomic findings, we suggest at least two potential pathways leading to RT-associated bladder cancer: The first occurs in the setting of field cancerization related to smoking or preexisting genetic alterations and leads to the development of more aggressive bladder tumors, and the second involves RT initiating the oncogenic process in otherwise healthy urothelium, leading to a longer latency and less aggressive disease. SIGNIFICANCE: Clinicogenomic analysis of radiation-associated bladder cancer uncovered mutational signatures that, in addition to a short tumor latency, smoking, and CDKN2A loss, are associated with a poor outcome. These clinical and genomic features provide a potential method to identify patients with prostate cancer who are at an increased risk for the development of aggressive bladder cancer following prostate RT.

Pharmacological Wnt ligand inhibition overcomes key tumor-mediated resistance pathways to anti-PD-1 immunotherapy.

While immune checkpoint blockade is associated with prolonged responses in multiple cancers, most patients still do not benefit from this therapeutic strategy. The Wnt-ß-catenin pathway is associated with diminished T cell infiltration; however, activating mutations are rare, implicating a role for autocrine/paracrine Wnt ligand-driven signaling in immune evasion. In this study, we show that proximal mediators of the Wnt signaling pathway are associated with anti-PD-1 resistance, and pharmacologic inhibition of Wnt ligand signaling supports anti-PD-1 efficacy by reversing dendritic cell tolerization and the recruitment of granulocytic myeloid-derived suppressor cells in autochthonous tumor models. We further demonstrate that the inhibition of Wnt signaling promotes the development of a tumor microenvironment that is more conducive to favorable responses to checkpoint blockade in cancer patients. These findings support a rationale for Wnt ligand-focused treatment approaches in future immunotherapy clinical trials and suggest a strategy for selecting those tumors more responsive to Wnt inhibition.

A tumor-intrinsic PD-L1/NLRP3 inflammasome signaling pathway drives resistance to anti-PD-1 immunotherapy.

An in-depth understanding of immune escape mechanisms in cancer is likely to lead to innovative advances in immunotherapeutic strategies. However, much remains unknown regarding these mechanisms and how they impact immunotherapy resistance. Using several preclinical tumor models as well as clinical specimens, we identified a mechanism whereby CD8+ T cell activation in response to programmed cell death 1 (PD-1) blockade induced a programmed death ligand 1/NOD-, LRR-, and pyrin domain-containing protein 3 (PD-L1/NLRP3) inflammasome signaling cascade that ultimately led to the recruitment of granulocytic myeloid-derived suppressor cells (PMN-MDSCs) into tumor tissues, thereby dampening the resulting antitumor immune response. The genetic and pharmacologic inhibition of NLRP3 suppressed PMN-MDSC tumor infiltration and significantly augmented the efficacy of anti-PD-1 antibody immunotherapy. This pathway therefore represents a tumor-intrinsic mechanism of adaptive resistance to anti-PD-1 checkpoint inhibitor immunotherapy and is a promising target for future translational research.