Cytokines are soluble proteins that mediate cell-to-cell communication. Based on the discovery of the potent anti-tumour activities of several pro-inflammatory cytokines in animal models, clinical research led to the approval of recombinant interferon-alpha and interleukin-2 for the treatment of several malignancies, even if efficacy was only modest. These early milestones in immunotherapy have been followed by the recent addition to clinical practice of antibodies that inhibit immune checkpoints, as well as chimeric antigen receptor T cells. A renewed interest in the anti-tumour properties of cytokines has led to an exponential increase in the number of clinical trials that explore the safety and efficacy of cytokine-based drugs, not only as single agents, but also in combination with other immunomodulatory drugs. These second-generation drugs under clinical development include known molecules with novel mechanisms of action, new targets, and fusion proteins that increase half-life and target cytokine activity to the tumour microenvironment or to the desired effector immune cells. In addition, the detrimental activity of immunosuppressive cytokines can be blocked by antagonistic antibodies, small molecules, cytokine traps or siRNAs. In this review, we provide an overview of the novel trends in the cytokine immunotherapy field that are yielding therapeutic agents for clinical trials.

Highlights d Tumor-secreted CXCR1 and CXCR2 ligands induce extrusion of NETs d NETs protect tumor cells from CTL and NK cytotoxicity in 3D cultures d Inhibition of NETosis sensitizes tumors to PD-1+CTLA-4 dual checkpoint blockade d NETs impair contact of immune cytotoxic cells with tumor cells in living mice Authors

Cancer immunotherapy has revolutionized oncology practice. However, current protein and cell therapy tools used in cancer immunotherapy are far from perfect, and there is room for improvement regarding their efficacy and safety. RNA-based structures have diverse functions, ranging from gene expression and gene regulation to pro-inflammatory effects and the ability to specifically bind different molecules. These functions make them versatile tools that may advance cancer vaccines and immunomodulation, surpassing existing approaches. These technologies should not be considered as competitors of current immunotherapies but as partners in synergistic combinations and as a clear opportunity to reach more efficient and personalized results. RNA and RNA derivatives can be exploited therapeutically as a platform to encode protein sequences, provide innate pro-inflammatory signals to the immune system (such as those denoting viral infection), control the expression of other RNAs (including key immunosuppressive factors) post-transcriptionally and conform structural scaffoldings binding proteins that control immune cells by modifying their function. Nascent RNA immunotherapeutics include RNA vaccines encoding cancer neoantigens, mRNAs encoding immunomodulatory factors, viral RNA analogues, interference RNAs and protein-binding RNA aptamers. These approaches are already in early clinical development with promising safety and efficacy results.

Poly I:C is a powerful immune adjuvant as a result of its agonist activities on TLR-3, MDA5 and RIG-I. BO-112 is a nanoplexed formulation of Poly I:C complexed with polyethylenimine that causes tumor cell apoptosis showing immunogenic cell death features and which upon intratumoral release results in more prominent tumor infiltration by T lymphocytes. Intratumoral treatment with BO-112 of subcutaneous tumors derived from MC38, 4 T1 and B16-F10 leads to remarkable local disease control dependent on type-1 interferon and gamma-interferon. Some degree of control of non-injected tumor lesions following BO-112 intratumoral treatment was found in mice bearing bilateral B16-OVA melanomas, an activity which was enhanced with co-treatment with systemic anti-CD137 and anti-PD-L1 mAbs. More abundant CD8 + T lymphocytes were found in B16-OVA tumor-draining lymph nodes and in the tumor microenvironment following intratumoral BO-112 treatment, with enhanced numbers of tumor antigen-specific cytotoxic T lymphocytes. Genome-wide transcriptome analyses of injected tumor lesions were consistent with a marked upregulation of the type-I interferon pathway. Inspired by these data, intratumorally delivered BO-112 is being tested in cancer patients (NCT02828098). Electronic supplementary material The online version of this article (10.1186/s40425-019-0568-2) contains supplementary material, which is available to authorized users.

CD137 (4-1BB, TNF-receptor superfamily 9) is a surface glycoprotein of the TNFR family which can be induced on a variety of leukocyte subsets. On T and NK cells, CD137 is expressed following activation and, if ligated by its natural ligand (CD137L), conveys polyubiquitination-mediated signals via TNF receptor associated factor 2 that inhibit apoptosis, while enhancing proliferation and effector functions. CD137 thus behaves as a bona fide inducible costimulatory molecule. These functional properties of CD137 can be exploited in cancer immunotherapy by systemic administration of agonist monoclonal antibodies, which increase anticancer CTLs and enhance NK-cell-mediated antibodydependent cell-mediated cytotoxicity. Reportedly, anti-CD137 mAb and adoptive T-cell therapy strongly synergize, since (i) CD137 expression can be used to select the T cells endowed with the best activities against the tumor, (ii) costimulation of the lymphocyte cultures to be used in adoptive T-cell therapy can be done with CD137 agonist antibodies or CD137L, and (iii) synergistic effects upon coadministration of T cells and antibodies are readily observed in mouse models. Furthermore, the signaling cytoplasmic tail of CD137 is a key component of anti-CD19 chimeric antigen receptors that are used to redirect T cells against leukemia and lymphoma in the clinic. Ongoing phase II clinical trials with agonist antibodies and the presence of CD137 sequence in these successful chimeric antigen receptors highlight the importance of CD137 in oncoimmunology. Keywords A proposed model for CD137 signaling and its regulationSignaling via CD137 proceeds from ligated molecules at the cell surface, which become cross-linked either by trimerized ligand [14] or multivalent antibodies [3] (Fig 1). CD137 has been immunoprecipitated both as a monomer and as a dimer [2]. Extracellular binding of galectin-9 to CD137 has shown to be a factor keeping preassembled CD137 complexes together [9], which are then further cross-linked by antibody or by CD137 ligand (Fig 1). Across the TNFR family, it seems that trimers are the optimal signaling complexes [15], although a role for the formation of multimers of higher order is likely. The orientation of the monomers in the assembled complexes does not appear to be relevant for signaling, since mAbs binding different distant epitopes over the molecule have been shown to induce the same functional effects [16]. Although a conformational change of CD137 in these complexes cannot be definitively ruled out, this molecular event has not been observed with other members of the TNF-TNFR family and its requirement would not be absolute. CD137 associates with the adaptors TRAF-2 and TRAF-1 in its cytoplasmic tail, resulting in coimmunoprecipitation, which is enhanced upon CD137 activation in T cells [12, 17]. TRAF-2 is expressed in resting T lymphocytes, while TRAF-1 increases its levels of expression following activation [18]. In this way, the composition of the membrane CD137-TRAF complexes changes during lymphocyte activation.Th...

CD137 (4-1BB) is a surface glycoprotein that belongs to the tumour necrosis factor receptor family (TNFRSF9). Its expression is induced on activation on a number of leucocyte types. Interestingly, for cancer immunotherapy, CD137 becomes expressed on primed T and natural killer (NK) cells, which on ligation provides powerful costimulatory signals. Perturbation of CD137 by CD137L or agonist monoclonal antibodies on activated CD8 T cells protects such antigen-specific cytotoxic T lymphocytes from apoptosis, enhances effector functionalities and favours persistence and memory differentiation. As a consequence, agonist antibodies exert potent antitumour effects in mouse models and the CD137 signalling domain is critical in chimeric antigen receptors (CAR) of CAR T cells approved to be used in the clinic. New formats of CD137 agonist moieties are being clinically developed, seeking potent costimulation targeted to the tumour microenvironment to avoid liver inflammation side effects, that have thus far limited and delayed clinical development.

Highlights d mRNA electroporation engineers T cells to transiently produce single-chain IL-12 d IL-12-engineered T cells injected intratumorally reject local and distant tumors d Co-injection of anti-CD137 mAb or co-electroporation of CD137L enhances efficacy d IL-12-engineered TIL cultures successfully treat autologous engrafted tumors Authors Iñ aki Etxeberria, Elixabet Bolañ os,

Public neoantigens (NeoAgs) represent an elite class of shared cancer-specific epitopes derived from recurrently mutated driver genes. Here we describe a high-throughput platform combining single-cell transcriptomic and T cell receptor (TCR) sequencing to establish whether mutant PIK3CA, among the most frequently genomically altered driver oncogenes, generates an immunogenic public NeoAg. Using this strategy, we developed a panel of TCRs that recognize an endogenously processed neopeptide encompassing a common PIK3CA hotspot mutation restricted by the prevalent human leukocyte antigen (HLA)-A*03:01 allele. Mechanistically, immunogenicity to this public NeoAg arises from enhanced neopeptide/HLA complex stability caused by a preferred HLA anchor substitution. Structural studies indicated that the HLA-bound neopeptide presents a comparatively ‘featureless’ surface dominated by the peptide’s backbone. To bind this epitope with high specificity and affinity, we discovered that a lead TCR clinical candidate engages the neopeptide through an extended interface facilitated by an unusually long CDR3β loop. In patients with diverse malignancies, we observed NeoAg clonal conservation and spontaneous immunogenicity to the neoepitope. Finally, adoptive transfer of TCR-engineered T cells led to tumor regression in vivo in mice bearing PIK3CA-mutant tumors but not wild-type PIK3CA tumors. Together, these findings establish the immunogenicity and therapeutic potential of a mutant PIK3CA-derived public NeoAg.