Objective To better define the rare adverse event (AE) of diabetes mellitus associated with immune checkpoint inhibitors (ICIs). Design and methods We report the case of a lung cancer patient with diabetic ketoacidosis (DKA) and autoimmune thyroiditis during pembrolizumab treatment. We provide a systematic review of all published cases (PubMed/Web of Science/Cochrane, through November 2018) of autoimmune diabetes mellitus related to blockade of the cytotoxic T-lymphocyte antigen 4 (CTLA-4)-, programmed cell death 1 (PD-1) receptor or its ligand (PD-L1) or combination (ICI) therapy. Results Our literature search identified 90 patient cases (our case excluded). Most patients were treated with anti-PD-1 or anti-PD-L1 as monotherapy (79%) or in combination with CTLA-4 blockade (15%). On average, diabetes mellitus was diagnosed after 4.5 cycles; earlier for combination ICI at 2.7 cycles. Early-onset diabetes mellitus (after one or two cycles) was observed during all treatment regimens. Diabetic ketoacidosis was present in 71%, while elevated lipase levels were detected in 52% (13/25). Islet autoantibodies were positive in 53% of patients with a predominance of glutamic acid decarboxylase antibodies. Susceptible HLA genotypes were present in 65% (mostly DR4). Thyroid dysfunction was the most frequent other endocrine AE at 24% incidence in this patient population. Conclusion ICI-related diabetes mellitus is a rare but often life-threatening metabolic urgency of which health-care professionals and patients should be aware. Close monitoring of blood glucose and prompt endocrine investigation in case of hyperglycemia is advisable. Predisposing factors such as HLA genotype might explain why some individuals are at risk.

The use of tumor-associated antigen (TAA) mRNA for therapeutic purposes is under active investigation. To be effective, mRNA vaccines need to deliver activation stimuli in addition to TAAs to dendritic cells (DC). In this study, we evaluated whether intranodal delivery of TAA mRNA together with TriMix, a mix of mRNA encoding CD40 ligand, constitutive active Toll-like receptor 4 and CD70, results in the in situ modification and maturation of DCs, hence, priming of TAA-specific T cells. We showed selective uptake and translation of mRNA in vivo by lymph node resident CD11c þ cells. This process was hampered by codelivery of classical maturation stimuli but not by TriMix mRNA. Importantly, TriMix mRNA induced a T-cell-attracting and stimulatory environment, including recruitment of antigen-specific CD4 þ and CD8 þ T cells and CTLs against various TAAs. In several mouse tumor models, mRNA vaccination was as efficient in CTL induction and therapy response as vaccination with mRNAelectroporated DCs. Together, our findings suggest that intranodal administration of TAA mRNA together with mRNA encoding immunomodulating molecules is a promising vaccination strategy. Cancer Res; 72(7); 1661-71. Ó2012 AACR.

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The release of cytokines by T cells strongly defines their functional activity in vivo. The ability to produce multiple cytokines has been associated with beneficial immune responses in cancer and infectious diseases, while their progressive loss is associated with T-cell exhaustion, senescence and anergy. Consequently, strategies that enhance the multifunctional status of T cells are a key for immunotherapy. Dendritic cells (DCs) are professional antigen presenting cells that regulate T-cell functions by providing positive and negative co-stimulatory signals. A key negative regulator of T-cell activity is provided by binding of programmed death-1 (PD-1) receptor on activated T cells, to its ligand PD-L1, expressed on DCs. We investigated the impact of interfering with PD-L1/PD-1 co-stimulation on the multifunctionality of T cells, by expression of the soluble extracellular part of PD-1 (sPD-1) or PD-L1 (sPD-L1) in human monocyte-derived DCs during antigen presentation. Expression, secretion and binding of these soluble molecules after mRNA electroporation were demonstrated. Modification of DCs with sPD-1 or sPD-L1 mRNA resulted in increased levels of the co-stimulatory molecule CD80 and a distinct cytokine profile, characterized by the secretion of IL-10 and TNF-α, respectively. Co-expression in DCs of sPD-1 and sPD-L1 with influenza virus nuclear protein 1 (Flu NP1) stimulated Flu NP1 memory T cells, with a significantly higher number of multifunctional T cells and increased cytokine secretion, while it did not induce regulatory T cells. These data provide a rationale for the inclusion of interfering sPD-1 or sPD-L1 in DC-based immunotherapeutic strategies.

Regulatory T cells (Tregs) counteract anticancer immune responses through a number of mechanisms, limiting dendritic cell (DC)–based anticancer immunotherapy. In this study, we investigated the influence of various DC activation stimuli on the Treg functionality. We compared DCs activated by electroporation with mRNA encoding constitutively active TLR4 (caTLR4) and CD40 ligand (DiMix-DCs), or these factors together with mRNA encoding the costimulatory molecule CD70 (TriMix-DCs) with DCs maturated in the presence of a mixture of inflammatory cytokines (DCs maturated with a combination of the cytokines IL-1β, IL-6, TNF-α, and PGE2) for their ability to counteract Tregs on different levels. We first demonstrated that there was no difference in the extent of Treg induction starting from CD4+CD25− T cells under the influence of the different DC maturation stimuli. Second, we showed that both DiMix- and TriMix-DCs could partly alleviate Treg inhibition of CD8+ T cells. Third, we observed that CD8+ T cells that had been precultured with DiMix-DCs or TriMix-DCs were partially protected against subsequent Treg suppression. Finally, we showed that Tregs cocultured in the presence of TriMix-DCs, but not DiMix-DCs, partially lost their suppressive capacity. This was accompanied by a decrease in CD27 and CD25 expression on Tregs, as well as an increase in the expression of T-bet and secretion of IFN-γ, TNF-α, and IL-10, suggesting a shift of the Treg phenotype toward a Th1 phenotype. In conclusion, these data suggest that TriMix-DCs are not only able to suppress Treg functions, but moreover could be able to reprogram Tregs to Th1 cells under certain circumstances.