The transcriptome of lung tumor-infiltrating dendritic cells reveals a tumor-supporting phenotype and a microRNA signature with negative impact on clinical outcome

Targeting immunomodulatory pathways has ushered a new era in lung cancer therapy. Further progress requires deeper insights into the biology of immune cells in the lung cancer micro-environment. Dendritic cells (DCs) represent a heterogeneous and highly plastic immune cell system with a central role in controlling immune responses. The intratumoral infiltration and activation status of DCs are emerging as clinically relevant parameters in lung cancer. In this study, we used an orthotopic preclinical model of lung cancer to dissect how the lung tumor micro-environment affects tissue-resident DCs and extract novel biologically and clinically relevant information. Lung tumor-infiltrating leukocytes expressing generic DC markers were found to predominantly consist of CD11b(+) cells that, compare with peritumoral lung DC counterparts, strongly overexpress the T-cell inhibitory molecule PD-L1 and acquire classical surface markers of tumor-associated macrophages (TAMs). Transcriptome analysis of these CD11b(+) tumor-infiltrating DCs (TIDCs) indicates impaired antitumoral immunogenicity, confirms the skewing toward TAM-related features, and indicates exposure to a hypoxic environment. In parallel, TIDCs display a specific microRNA (miRNA) signature dominated by the prototypical lung cancer oncomir miR-31. In vitro, hypoxia drives intrinsic miR-31 expression in CD11b(+) DCs. Conditioned medium of miR-31 overexpressing CD11b(+) DCs induces pro-invasive lung cancer cell shape changes and is enriched with pro-metastatic soluble factors. Finally, analysis of TCGA datasets reveals that the TIDC-associated miRNA signature has a negative prognostic impact in non-small cell lung cancer. Together, these data suggest a novel mechanism through which the lung cancer micro-environment exploits the plasticity of the DC system to support tumoral progression

The transcriptome of lung tumor-infiltrating dendritic cells reveals a tumor-supporting phenotype and a microRNA signature with negative impact on clinical outcome

Targeting immunomodulatory pathways has ushered a new era in lung cancer therapy. Further progress requires deeper insights into the biology of immune cells in th

An accelerated, clinical-grade protocol to generate high yields of type 1-polarizing messenger RNA loaded dendritic cells for cancer vaccination

Background: Many efforts have been devoted to improve the performance of dendritic cell (DC) based cancer vaccines. Ideally, a DC vaccine should induce robust type 1 polarized T-cell responses and efficiently expand antigen (Ag)-specific cytotoxic T-cells, while being applicable regardless of patient human leukocyte antigen (HLA) type. Production time should be short, while maximally being good manufacturing practice (GMP) compliant. We developed a method that caters to all of these demands and demonstrated the superiority of the resulting product compared with DCs generated using a well-established "classical" protocol. Methods: Immunomagnetically purified monocytes were cultured in a closed system for 3 days in GMP-compliant serum-free medium and cytokines, and matured for 24 h using monophosphoryl lipid A (MPLA)+ interferon -gamma (IFN-y). Mature DCs were electroporated with messenger RNA (mRNA) encoding full-length antigen and cryopreserved. "Classical" DCs were cultured for 8 days in flasks, with one round of medium and cytokine supplementation, and matured with tumor necrosis factor alpha (TNF-alpha) + prostaglandin E2 (PGE2) during the last 2 days. Results: Four-day MPLA/IFN-y matured DCs were superior to 8-day TNF-alpha/PGE2 matured DCs in terms of yield, co-stimulatory/coinhibitory molecule expression, resilience to electroporation and cryopreservation and type 1 polarizing cytokine and chemokine release after cell thawing. Electroporated and cryopreserved DCs according to our protocol efficiently present epitopes from tumor antigen-encoding mRNA, inducing a strong expansion of antigen-specific CD8+ T-cells with full cytolytic capacity. Conclusion: We demonstrate using a GMP-compliant culture protocol the feasibility of generating high yields of mature DCs in a short time, with a superior immunogenic profile compared with 8-day TNF-alpha/PGE2 matured DCs, and capable of inducing vigorous cytotoxic T-cell responses to antigen from electroporated mRNA. This method is now being applied in our clinical trial program

Treatment of a patient with severe cytomegalovirus (CMV) infection after haploidentical stem cell transplantation with donor-derived CMV-specific T cells

Objectives: Cytomegalovirus (CMV) infection is one of the most common complications in allogeneic hematopoietic stem cell transplant (allo-HSCT) recipients. The classic antiviral treatments have shown clinical efficacy but are often associated with drug resistance. Reconstitution of CMV-specific cellular immunity is essential in controlling CMV infection; therefore, adoptive transfer of CMV-specific T cells is a promising treatment option. We treated a patient with a multidrug resistant CMV infection after haploidentical HSCT with CMV-specific T cells. Methods: The T cells were derived from the HSCT donor who was CMV seropositive. We generated the T cells by a short-term Good Manufacturing Practice (GMP) grade protocol in which a leukapheresis product of the HSCT donor was stimulated with the immunodominant antigen pp65 and interferon-γ secreting cells were isolated. A total of 5 × 105 T cells were administered to the patient within 30 hours after leukapheresis. Results: The patient was closely monitored for reconstitution of antiviral T cell immunity and viral replication after adoptive T cell transfer. We observed an in vivo expansion of both CD4+ and CD8+ CMV-specific T cells associated with a significant decrease in viral burden and clinical improvement. Conclusion: This case report further supports the feasibility and effectiveness of adoptive donor T cell transfer for the treatment of drug resistant CMV infections after allo-HSCT

Small-scale manufacturing of neoantigen-encoding messenger RNA for early-phase clinical trials

Messenger RNA (mRNA) has become a promising tool in therapeutic cancer vaccine strategies. Owing to its flexible design and rapid production, mRNA is an attractive antigen delivery format for cancer vaccines targeting mutated peptides expressed in a tumor-the so-called neoantigens. These neoantigens are rarely shared between patients, and inclusion of these antigens in a vaccine requires the production of individual batches of patient-tailored mRNA. The authors have developed MIDRIXNEO, a personalized mRNA-loaded dendritic cell vaccine targeting tumor neoantigens, which is currently being evaluated in a phase 1 clinical study in lung cancer patients. To facilitate this study, the authors set up a Good Manufacturing Practice (GMP)-compliant production process for the manufacture of small batches of personalized neoantigenencoding mRNA. In this article, the authors describe the complete mRNA production process and the extensive quality assessment to which the mRNA is subjected. Validation runs have shown that the process delivers mRNA of reproducible, high quality. This process is now successfully applied for the production of neoantigen-encoding mRNA for the clinical evaluation of MIDRIXNEO. To the authors' knowledge, this is the first time that a GMP-based production process of patient-tailored neoantigen mRNA has been described. (c) 2021 International Society for Cell & Gene Therapy. Published by Elsevier Inc. This is an open access articl