Peripheral Blood IFN Responses to Toll-Like Receptor 1/2 Signaling Associate with Longer Survival in Men with Metastatic Prostate Cancer Treated with Sipuleucel-T.

Unlabelled: Mounting evidence links systemic innate immunity with cancer immune surveillance. In advanced metastatic castration-resistant prostate cancer (mCRPC), Black patients have been found to have increased inflammatory markers and longer survival after sipuleucel-T (sip-T) therapy, an FDA-approved, autologous cell therapy. We hypothesized these differences may be explained by previously reported ancestral differences in pattern recognition receptor signaling, which broadly governs innate inflammation to control adaptive immune cell activation, chemotaxis, and functionality.

Cancer mRNA vaccines: clinical advances and future opportunities.

mRNA vaccines have been revolutionary in terms of their rapid development and prevention of SARS-CoV-2 infections during the COVID-19 pandemic, and this technology has considerable potential for application to the treatment of cancer. Compared with traditional cancer vaccines based on proteins or peptides, mRNA vaccines reconcile the needs for both personalization and commercialization in a manner that is unique to each patient but not beholden to their HLA haplotype. A further advantage of mRNA vaccines is the availability of engineering strategies to improve their stability while retaining immunogenicity, enabling the induction of complementary innate and adaptive immune responses.

Functional reprogramming of peripheral blood monocytes by soluble mediators in patients with pancreatic cancer and intraductal papillary mucinous neoplasms.

Background: Monocytes and monocyte-derived tumor infiltrating cells have been implicated in the immunosuppression and immune evasion associated with pancreatic adenocarcinoma (PDAC). Yet, precisely how monocytes in the periphery and tumor microenvironment in patients with intraductal papillary mucinous neoplasm (IPMN), a precursor lesion to PDAC, change during disease progression has not been defined. Here we functionally profiled the peripheral immune system and characterized the tumor microenvironment of patients with both IPMN and PDAC.

The Quest for mRNA Vaccines.

The success of mRNA vaccines against COVID-19 is nothing short of a medical revolution. Given its chemical lability the use of mRNA as a therapeutic has been counterintuitive and met with skepticism. The development of mRNA-based COVID-19 vaccines was the culmination of long and painstaking efforts by many investigators spanning over 30 years and culminating with the seminal studies of Kariko and Weissman.

Multimodality analysis confers a prognostic benefit of a T-cell infiltrated tumor microenvironment and peripheral immune status in patients with melanoma.

Background: We previously reported results from a phase 1 study testing intratumoral recombinant poliovirus, lerapolturev, in 12 melanoma patients. All 12 patients received anti-PD-1 systemic therapy before lerapolturev, and 11 of these 12 patients also received anti-PD-1 after lerapolturev. In preclinical models lerapolturev induces intratumoral innate inflammation that engages antitumor T cells.

Spatial biology analysis reveals B cell follicles in secondary lymphoid structures may regulate anti-tumor responses at initial melanoma diagnosis.

Introduction: B cells are key regulators of immune responses in melanoma. We aimed to explore differences in the histologic location and activation status of B cell follicles in sentinel lymph nodes (SLN) of melanoma patients.

Methods: Flow cytometry was performed on fresh tumor draining lymph nodes (LN).

Controlling cancer-induced inflammation with a nucleic acid scavenger prevents lung metastasis in murine models of breast cancer.

Tumor cells release nucleic acid-containing proinflammatory complexes, termed nucleic acid-containing damage-associated molecular patterns (NA DAMPs), passively upon death and actively during stress. NA DAMPs activate pattern recognition receptors on cells in the tumor microenvironment leading to prolonged and intensified inflammation that potentiates metastasis. No strategy exists to control endogenous or therapy-induced inflammation in cancer patients.

Paracrine Wnt5a-β-Catenin Signaling Triggers a Metabolic Program that Drives Dendritic Cell Tolerization.

Despite recent advances, many cancers remain refractory to available immunotherapeutic strategies. Emerging evidence indicates that the tolerization of local dendritic cells (DCs) within the tumor microenvironment promotes immune evasion. Here, we have described a mechanism by which melanomas establish a site of immune privilege via a paracrine Wnt5a-β-catenin-peroxisome proliferator-activated receptor-γ (PPAR-γ) signaling pathway that drives fatty acid oxidation (FAO) in DCs by upregulating the expression of the carnitine palmitoyltransferase-1A (CPT1A) fatty acid transporter.

Recombinant oncolytic poliovirus, PVSRIPO, has potent cytotoxic and innate inflammatory effects, mediating therapy in human breast and prostate cancer xenograft models.

Intratumoral inoculation of viruses with tumor-selective cytotoxicity may induce cancer cell death and, thereby, shrink neoplastic lesions. It is unlikely, however, that viral tumor cell killing alone could produce meaningful, durable clinical responses, as clinically suitable 'oncolytic' viruses are severely attenuated and their spread and propagation are opposed by host immunity. Thus, a more propitious event in this context is the innate antiviral response to intratumoral virus administration, in particular for recruiting durable adaptive immune effector responses.

The RNAissance period.

The concept that RNA has played a major role in the evolution of life stems from the "RNA World" hypothesis. This role of RNA was not immediately appreciated. Similarly, the scientific community has just recently begun to recognize the true potential of RNA as the drug of choice for gene therapy, cellular reprogramming and vaccination.

Ex vivo generation of dendritic cells from cryopreserved, post-induction chemotherapy, mobilized leukapheresis from pediatric patients with medulloblastoma.

Generation of patient-derived, autologous dendritic cells (DCs) is a critical component of cancer immunotherapy with ex vivo-generated, tumor antigen-loaded DCs. An important factor in the ability to generate DCs is the potential impact of prior therapies on DC phenotype and function. We investigated the ability to generate DCs using cells harvested from pediatric patients with medulloblastoma for potential evaluation of DC-RNA based vaccination approach in this patient population.

High-throughput identification and dendritic cell-based functional validation of MHC class I-restricted Mycobacterium tuberculosis epitopes.

Emergence of drug-resistant strains of the pathogen Mycobacterium tuberculosis (Mtb) and the ineffectiveness of BCG in curtailing Mtb infection makes vaccine development for tuberculosis an important objective. Identifying immunogenic CD8+ T cell peptide epitopes is necessary for peptide-based vaccine strategies. We present a three-tiered strategy for identifying and validating immunogenic peptides: first, identify peptides that form stable complexes with class I MHC molecules; second, determine whether cytotoxic T lymphocytes (CTLs) raised against the whole protein antigen recognize and lyse target cells pulsed with peptides that passed step 1; third, determine whether peptides that passed step 2, when administered in vivo as a vaccine in HLA-A2 transgenic mice, elicit CTLs that lyse target cells expressing the whole protein antigen.

Recognition and killing of autologous, primary glioblastoma tumor cells by human cytomegalovirus pp65-specific cytotoxic T cells.

Purpose: Despite aggressive conventional therapy, glioblastoma (GBM) remains uniformly lethal. Immunotherapy, in which the immune system is harnessed to specifically attack malignant cells, offers a treatment option with less toxicity. The expression of cytomegalovirus (CMV) antigens in GBM presents a unique opportunity to target these viral proteins for tumor immunotherapy.

Whole blood cells loaded with messenger RNA as an anti-tumor vaccine.

The use of a cell-based vaccine composed of autologous whole blood cells loaded with mRNA is described. Mice immunized with whole blood cells loaded with mRNA encoding antigen develop anti-tumor immunity comparable to DC-RNA immunization. This approach offers a simple and affordable alternative to RNA-based cellular therapy by circumventing complex, laborious and expensive ex vivo manipulations required for DC-based immunizations.

Melanoma immunotherapy using mature DCs expressing the constitutive proteasome.

Background: Many cancers, including melanoma, exclusively express constitutive proteasomes (cPs) and are unable to express immunoproteasomes (iPs). In contrast, mature DCs used for immunotherapy exclusively express iPs. Since proteasomes generate peptides presented by HLA class I molecules, we hypothesized that mature melanoma antigen-loaded DCs engineered to process antigens through cPs would be superior inducers of antimelanoma immunity in vivo.

Immunologic targeting of FOXP3 in inflammatory breast cancer cells.

The forkhead transcription factor FOXP3 is necessary for induction of regulatory T lymphocytes (Tregs) and their immunosuppressive function. We have previously demonstrated that targeting Tregs by vaccination of mice with murine FOXP3 mRNA-transfected dendritic cells (DCs) elicits FOXP3-specific T cell responses and enhances tumor immunity. It is clear that FOXP3 expression is not restricted to T-cell lineage and herein, using RT-PCR, flow cytometry, and western immunoblot we demonstrate for the first time that FOXP3 is expressed in inflammatory breast cancer (IBC) cells, SUM149 (triple negative, ErbB1-activated) and SUM190 (ErbB2-overexpressing).

Programming human dendritic cells with mRNA.

Transfecting with in vitro transcribed, protein-encoding mRNA is a simple yet effective method to express high levels of the desired RNA-encoded proteins in primary cells. Cells can be transfected with antigen-encoding mRNA, which is translated into protein and is processed by the cellular antigen-processing pathway to generate antigen-presenting cells. Another elegant and increasingly popular application is to transfect cells with mRNA that encodes immune modulating molecules (cytokines, chemokines, toll-like receptors (TLRs), immune receptor ligands, immune receptor targeting antibodies) which, when translated into protein, can program cell behavior and/or function.

Engineering B cells with mRNA.

Ex vivo activated B cells are an alternative source of antigen presenting cells (APC). However, the ability of ex vivo activated B cells to function as potent APCs has been a concern especially when compared to dendritic cells (DC). Herein, we introduce a strategy to modulate antigen presentation and immune stimulation functions of activated B cells by co-transfection with multiple mRNAs encoding costimulatory molecules (OX40L, 4-1BBL, and CD80), cytokines (IL-12p35 and IL-12p40) and antigen.

Enhancement of anti-tumor immunity through local modulation of CTLA-4 and GITR by dendritic cells.

Cancer vaccines have now demonstrated clinical efficacy, but immune modulatory mechanisms that prevent autoimmunity limit their effectiveness. Systemic administration of mAbs targeting the immune modulatory receptors CTLA-4 and glucocorticoid-induced TNFR-related protein (GITR) on Treg and effector T cells augments anti-tumor immunity both experimentally and clinically, but can induce life-threatening autoimmunity. We hypothesized that local delivery of anti-CTLA-4 and anti-GITR mAbs to the sites where T cells and tumor antigen-loaded DC vaccines interact would enhance the induction of anti-tumor immunity while avoiding autoimmunity.

RNA as performance-enhancers for dendritic cells.

Importance Of The Field: Although studies have demonstrated that antigen-loaded dendritic cells (DC) elicit antigen-specific immune responses, the clinical benefit from DC-based cancer immunotherapy remains low. RNA, in the form of mRNA, has not only been used as a source of antigen but more recently as a way to stimulate DC to produce immunostimulatory molecules. As siRNA it has allowed researchers to modify DC to produce a favorable cytokine profile or to present antigen that may generate the desired immune response.

Assembling OX40 aptamers on a molecular scaffold to create a receptor-activating aptamer.

We show that a molecular scaffold can be utilized to convert a receptor binding aptamer into a receptor agonist. Many receptors (including tumor necrosis receptor family members) are activated when they are multimerized on the cell surface. Molecular scaffolds have been utilized to assemble multiple receptor binding peptide ligands to generate activators of such receptors.

Activated B cells modified by electroporation of multiple mRNAs encoding immune stimulatory molecules are comparable to mature dendritic cells in inducing in vitro antigen-specific T-cell responses.

Ex-vivo-activated B cells are an alternative source of antigen-presenting cells (APCs) and a potential replacement for dendritic cells (DCs) in immunotherapy. However, the ability of ex-vivo-activated B cells to function as potent APCs has been a concern, especially when compared to DCs. Our study investigated whether modification of activated B cells with immune stimulatory molecules could enhance the ability of activated B cells to stimulate T cells.

Robust CD4+ and CD8+ T cell responses to SIV using mRNA-transfected DC expressing autologous viral Ag.

A potentially powerful strategy for therapeutic HIV vaccination is the use of DC transfected with mRNA encoding autologous viral Ag, as epitopes presented by transfected DC would exactly reflect those expressed by infected cells in the individual. Using human and rhesus macaque monocyte-derived DC, we show that nucleofection is a superior method for mRNA transfection, resulting in high-level protein expression and DC maturation. DC transfected with SIV gag isolated from an infected monkey stimulated robust Ag-specific recall T cell responses of similar magnitude to those induced by peptide-pulsed PBMC that were predominantly CD8+ T cell mediated.

Vaccination against the forkhead family transcription factor Foxp3 enhances tumor immunity.

Depletion of CD4+CD25+ regulatory T cells (Treg) by treatment with alphaCD25 antibody synergizes with vaccination protocols to engender protective immunity in mice. The effectiveness of targeting CD25 to eliminate Treg is limited by the fact that CD25, the low-affinity interleukin-2 receptor, is up-regulated on conventional T cells. At present, foxp3 is the only product known to be exclusively expressed in Treg of mice.