Dendritic cell (DC)-based vaccination for cancer treatment has seen considerable development over recent decades. However, this field is currently in a state of flux toward niche-applications, owing to recent paradigm-shifts in immuno-oncology mobilized by T cell-targeting immunotherapies. DC vaccines are typically generated using autologous (patient-derived) DCs exposed to tumor-associated or -specific antigens (TAAs or TSAs), in the presence of immunostimulatory molecules to induce DC maturation, followed by reinfusion into patients. Accordingly, DC vaccines can induce TAA/TSA-specific CD8+/CD4+ T cell responses. Yet, DC vaccination still shows suboptimal anti-tumor efficacy in the clinic. Extensive efforts are ongoing to improve the immunogenicity and efficacy of DC vaccines, often by employing combinatorial chemo-immunotherapy regimens. In this Trial Watch, we summarize the recent preclinical and clinical developments in this field and discuss the ongoing trends and future perspectives of DC-based immunotherapy for oncological indications.

• Klíčová slova
• DAMPs, Dendritic cells, T cell priming, TAAs, antigen cross-presentation, clinical trial, immune checkpoint blockers, tumor-infiltrating lymphocytes,
• MeSH
• antigeny nádorové MeSH
• dendritické buňky MeSH
• imunoterapie MeSH
• lidé MeSH
• nádory * farmakoterapie   MeSH
• protinádorové vakcíny * terapeutické užití   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• antigeny nádorové MeSH
• protinádorové vakcíny * MeSH

The inevitability of evolution of the adaptive immune system with its mechanism of randomly rearranging segments of the T cell receptor (TCR) gene is the generation of self-reactive clones. For the sake of prevention of autoimmunity, these clones must be eliminated from the pool of circulating T cells. This process occurs largely in the thymic medulla where the strength of affinity between TCR and self-peptide MHC complexes is the factor determining thymocyte fate. Thus, the display of self-antigens in the thymus by thymic antigen presenting cells, which are comprised of medullary thymic epithelial (mTECs) and dendritic cells (DCs), is fundamental for the establishment of T cell central tolerance. Whereas mTECs produce and present antigens in a direct, self-autonomous manner, thymic DCs can acquire these mTEC-derived antigens by cooperative antigen transfer (CAT), and thus present them indirectly. While the basic characteristics for both direct and indirect presentation of self-antigens are currently known, recent reports that describe the heterogeneity of mTEC and DC subsets, their presentation capacity, and the potentially non-redundant roles in T cell selection processes represents another level of complexity which we are attempting to unravel. In this review, we underscore the seminal studies relevant to these topics with an emphasis on new observations pertinent to the mechanism of CAT and its cellular trajectories underpinning the preferential distribution of thymic epithelial cell-derived self-antigens to specific subsets of DC. Identification of molecular determinants which control CAT would significantly advance our understanding of how the cellularly targeted presentation of thymic self-antigens is functionally coupled to the T cell selection process.

• Klíčová slova
• antigen presentation, central tolerance, cooperative antigen transfer, dendritic cells, thymic epithelial cells, thymus,
• MeSH
• autoantigeny * MeSH
• centrální tolerance MeSH
• dendritické buňky * MeSH
• epitelové buňky MeSH
• receptory antigenů T-buněk MeSH
• thymus MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Názvy látek
• autoantigeny * MeSH
• receptory antigenů T-buněk MeSH

Dendritic cells (DCs) are key regulators of immune responses that operate at the interface between innate and adaptive immunity, and defects in DC functions contribute to the pathogenesis of a variety of disorders. For instance, cancer evolves in the context of limited DC activity, and some autoimmune diseases are initiated by DC-dependent antigen presentation. Thus, correcting aberrant DC functions stands out as a promising therapeutic paradigm for a variety of diseases, as demonstrated by an abundant preclinical and clinical literature accumulating over the past two decades. However, the therapeutic potential of DC-targeting approaches remains to be fully exploited in the clinic. Here, we discuss the unique features of DCs that underlie the high therapeutic potential of DC-targeting strategies and critically analyze the obstacles that have prevented the full realization of this promising paradigm.

• Klíčová slova
• autoimmune disorders, cancer, dendritic cells, immunotherapy, vaccine preparation,
• MeSH
• antigen prezentující buňky imunologie   metabolismus   MeSH
• autoimunita MeSH
• autoimunitní nemoci etiologie   metabolismus   terapie   MeSH
• buněčná diferenciace genetika   imunologie   MeSH
• dendritické buňky imunologie   metabolismus   MeSH
• imunita * MeSH
• imunologická tolerance * MeSH
• imunoterapie MeSH
• lidé MeSH
• mezibuněčná komunikace MeSH
• náchylnost k nemoci MeSH
• nádory etiologie   metabolismus   patologie   terapie   MeSH
• plasticita buňky genetika   imunologie   MeSH
• prezentace antigenu imunologie   MeSH
• protinádorové vakcíny aplikace a dávkování   imunologie   MeSH
• T-lymfocyty imunologie   metabolismus   MeSH
• výsledek terapie MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Názvy látek
• protinádorové vakcíny MeSH

Cellular immune reactions against non-self-epitopes require activation of cytotoxic CD8+ T-cells via cross-presentation of MHC class I-restricted peptides by professional antigen presenting cells (pAPCs), with the consequent detection and elimination of cells expressing the same antigens via the endogenous (direct) pathway. The source of peptides for the endogenous pathway is constituted of alternative mRNA translation products; however, it is still unclear which source of peptides is used for cross-presentation. Furthermore, the presentation of non-canonical translation products, produced during a non-conventional translation event, on class I molecules of tumor cells has been reported but how these peptides are generated, presented to pAPCs, and their capacity to stimulate CD8+ T cells is still not known. Here, we report that pioneer translation peptides (PTPs) derived from intron or exon pre-mRNAs can serve as tumor-associated antigens (TA-PTPs) and are delivered from the producing tumor cells to pAPCs via exosomes where they are processed by the cytosolic pathway. Injection of TA-PTPs and tumor-derived exosomes efficiently induce CD8+ T-cell proliferation and prevent tumor growth in mice. Our results show that TA-PTPs represent an efficient source of antigenic peptides for CD8+ T cell activation and that full-length proteins are not required for cross-presentation. These findings can have interesting implications for generating tolerance and for designing vectors to generate vaccines.

• Klíčová slova
• Exosomes, MHC-I antigen cross presentation, pioneer translation products, tumor rejection, vaccines,
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

The use of patient-derived dendritic cells (DCs) as a means to elicit therapeutically relevant immune responses in cancer patients has been extensively investigated throughout the past decade. In this context, DCs are generally expanded, exposed to autologous tumor cell lysates or loaded with specific tumor-associated antigens (TAAs), and then reintroduced into patients, often in combination with one or more immunostimulatory agents. As an alternative, TAAs are targeted to DCs in vivo by means of monoclonal antibodies, carbohydrate moieties or viral vectors specific for DC receptors. All these approaches have been shown to (re)activate tumor-specific immune responses in mice, often mediating robust therapeutic effects. In 2010, the first DC-based preparation (sipuleucel-T, also known as Provenge®) has been approved by the US Food and Drug Administration (FDA) for use in humans. Reflecting the central position occupied by DCs in the regulation of immunological tolerance and adaptive immunity, the interest in harnessing them for the development of novel immunotherapeutic anticancer regimens remains high. Here, we summarize recent advances in the preclinical and clinical development of DC-based anticancer therapeutics.

• Klíčová slova
• DC, dendritic cell, DC-based vaccination, FDA, Food and Drug Administration, IFN, interferon, MRC1, mannose receptor, C type 1, MUC1, mucin 1, TAA, tumor-associated antigen, TLR, Toll-like receptor, Toll-like receptor agonists, Treg, regulatory T cell, WT1, Wilms tumor 1, antigen cross-presentation, autophagy, iDC, immature DC, immunogenic cell death, mDC, mature DC, pDC, plasmacytoid DC, regulatory T cells,
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH