NSCLC: Non-small cell lung cancer. therapy. We discuss the availability and relevance Moxonidine Hydrochloride of preclinical models as well as currently available tools and knowledge from a drug development perspective. Finally, we compare advantages and disadvantages of existing therapeutic concepts and propose a role for V9V2 T cells in immune-oncology next to Cluster of Differentiation (CD) 3 activating therapies. later described as Coleys toxin [1]. Even though clinical statistics were not performed at todays scale, Coley left an amazing amount of data to suggest that although this treatment resulted in severe toxicity, cancer could be treated and even cured by bacterial infection. Although subsequent therapeutic discoveries have led to the emergence of alternative approaches to treat cancer, Moxonidine Hydrochloride including radiotherapy, chemotherapy and targeted therapies [2], bacterial treatment has been further evaluated in the clinic. Bacille Calmette-Guerin (BCG) is a Food and Drug Administration (FDA)-approved live attenuated preparation of (TICE?, Organon Teknika Corp. or PACIS?, BioChemPharma) and currently used as a standard immunotherapy for the treatment of bladder cancer [3]. Research of the past decades has drawn a map of a highly diversified and sensitive alarm system that has evolved to detect non-self structures Mouse monoclonal to Myeloperoxidase of pathogenic intruders or molecular indicators of damaged cells. Pioneering work by Charles Janeway and Ruslan Medzhitov predicted and subsequently identified the first pathogen pattern recognition receptors and highlighted the importance of the innate immune system in the overall immune response [4]. The innate immune system recognizes pathogen-associated molecular patterns (PAMPs) or endogenous damage-associated molecular patterns (DAMPs), e.g., derived from essential bacterial functional or structural components, such as RNA or cell wall lipopolysaccharide (LPS) [5]. In the 21st century, the responsible mediators and mechanisms of the anti-tumor activity of Coleys toxin were identified: bacterial DNA and LPS stimulate Toll-Like Receptor (TLR) 9 and TLR4 signaling on a variety of immune cells, including Natural Killer (NK) cells and T cells, thereby enhancing their anti-tumor activity [6,7,8]. Additional studies have led to pathogen sensors being exploited therapeutically as drug targets to trigger a pro-inflammatory immune response [9,10]. Drug candidates acting as agonists of TLRs, of nucleotide-binding oligomerization domain (NOD)-like receptors (NLRs), or of stimulator of interferon genes (STING) entered the clinics with the aim to increase immune cell activation, infiltration and anti-tumor responses [11]. 2. BTN3A1 is a PAMP Receptor Butyrophilin 3 family member (BTN3) A1 is a transmembrane receptor that harbors two extracellular Immunoglobulin (Ig) -like domains and an intracellular B30.2 domain. The intracellular domain interacts directly Moxonidine Hydrochloride Moxonidine Hydrochloride with the bacterial metabolite (E)-4-hydroxy-3-methyl-but-2-enyl pyrophosphate (HMBPP) [12,13,14]. HMBPP is an essential intermediate product of the prokaryotic non-mevalonate/ 2-preparations [35] and infection of monocytes by or demonstrated that pathogen infection and phosphorylated antigens can activate and trigger expansion of V9V2 T cells [36]. Furthermore, strong V9V2 T cell responses against and infected host cells were demonstrated in in vivo infection models in macaques [37,38]. 4. V9V2T Cells in Cancer Bioinformatic analyses of large meta-genomic datasets determined the relative abundance of V9V2 T cells within tumors and correlated this with patient outcome. Tumor-infiltrating T lymphocytes ( TILs) were found in all tumor entities, albeit at low numbers. Importantly, a correlation between relative abundance of TILs and favorable response to immune checkpoint therapy in a variety of cancers was demonstrated [39,40]. Transformation can lead to differential expression or re-location of molecular signals to the surface of cancer cells and entail recognition by the immune system. V9V2 T cells have been shown to be able to recognize these markers of stress, including TCR ligands F1-ATPase in complex with apolipoprotein A-I, or hMSH2, a DNA mismatch repair protein [41,42]. It has been speculated that dysregulation of the mevalonate pathway during tumorigenesis is able to generate high intracellular levels of isopentenyl pyrophosphate (IPP) and that V9V2 T cells can sense this increase via signals to the BTN3A receptor [43]. IPP is the human metabolite most structurally homologous to bacterial HMBPP and has been shown to be able to trigger V9V2 T-cell activation and proliferation in an in vitro setting. It must be noted these effects required considerably higher concentrations (10000- to 30000-fold) of externally added IPP compared to the bacterial metabolite [44]. Although the intracellular IPP levels in cancer cells could be accumulated by up to 960-fold via downstream inhibition of farnesyl-diphosphate synthetase (FDPS) using aminobisphosphonates [45,46], without this intervention, only minimal cell killing was observed when V9V2 T cells were cultivated with a panel of tumor.