Acute infection is known to induce strong anti-tumor immune responses, but clinical translation has been hindered by the lack of an effective strategy to safely and consistently provoke a therapeutic response. These limitations are overcome with a novel treatment approach involving repeated subcutaneous delivery of a Klebsiella-derived investigational immunotherapeutic, QBKPN. In preclinical models of lung cancer, QBKPN administration consistently showed anti-cancer efficacy, which was dependent on Klebsiella pre-exposure, but was independent of adaptive immunity. Rather, QBKPN induced anti-tumor innate immunity that required NK cells and NKG2D engagement. QBKPN increased NK cells and macrophages in the lungs, altered macrophage polarization, and augmented the production of cytotoxic molecules. An exploratory trial in patients with non-small cell lung cancer demonstrated QBKPN was well tolerated, safe, and induced peripheral immune changes suggestive of macrophage polarization and reduction of PD-1 and PD-L1 expression on leukocytes. These data demonstrate preclinical efficacy, and clinical safety and tolerability, for this cancer immunotherapy strategy that exploits innate anti-tumor immune mechanisms.

Recent developments in understanding how the functional phenotype of the innate immune system is programmed has led to paradigm-shifting views on immunomodulation. These advances have overturned two long-held dogmas: (1) only adaptive immunity confers immunological memory; and, (2) innate immunity lacks specificity. This work describes the observation that innate immune effector cells appear to be differentially recruited to specific pathological sites when mobilized by distinct inactivated bacterial-based stimuli administered subcutaneously. The studies presented suggest that the immune system, upon detecting the first signs of a potential infection by a specific pathogen, tends to direct its resources to the compartment from which that pathogen is most likely originating. The findings from this work puts forth the novel hypothesis that the immunotherapeutic efficacy of a microbial-based stimulus for innate immune mobilization depends on the correct selection of the microbial species used as the stimulant and its relationship to the organ in which the pathology is present.

Recently it was reported that maintenance of mice at thermoneutral temperatures (TT, the temperature at which basal metabolism is sufficient to maintain body temperature, 30oC) enhanced antitumor immune responses and reduced tumor growth, relative to standard vivarium temperatures (ST, 22oC). We hypothesized that mice maintained at ST may have impaired production of T cell chemoattractant cytokines and subsequent T cell infiltration. In mice bearing breast tumors or solid or metastatic-like melanomas, intratumoral expression of CXCL9 and CXCL10 (CXCR3-cognate chemokines) was enhanced by maintenance of hosts in TT conditions. Further, tumors of TT-housed mice contained increased numbers of CD8+ T cells. We further hypothesized that the effect of temperature on T cell chemokine pathways may be a result of chronic cold stress, which may induce norepinephrine (NE) production and subsequent activation of β-adrenergic signaling pathways. We observed that pharmacologic blockade of β-adrenergic receptors in mice bearing solid or metastatic-like melanomas recapitulated the increased intratumoral expression of CXCL9 and CXCL10 and increased CD8+ T cell numbers. Because melanoma cells express β-adrenergic receptors, we suggest that chronic cold stress may induce systemic NE production, leading to tumor local activation of receptors and inhibition of tumor-derived chemokine production. These studies suggest potential interventions to improve existing T cell-based immunotherapies.

25Recent developments in understanding how the functional phenotype of the innate immune system 26 is programmed has led to paradigm-shifting views on immunomodulation. These advances have 27 overturned two long-held dogmas: only adaptive immunity confers immunological memory and 28 innate immunity lacks specificity. This work describes the novel observation that innate immune 29 effector cells can be recruited to specific tissues of the body where pathology is present by using 30 a microbial-based immune stimulus that consists of an inactivated pathogen that typically resides 31 or causes infection in that target tissue site. We demonstrate this principle using experimental 32 models of cancer and infection for which different subcutaneously delivered microbial-based 33 treatments were shown to induce the recruitment of immune effector cells to specific diseased 34 organs. Amelioration of disease in a given organ niche was dependent on matching the correct 35 microbial stimulus for the affected organ site but was independent of the nature of the pathology. 36 This observation intriguingly suggests that the immune system, upon pathogen recognition, tends 37 to direct its resources to the compartment in which the pathogen has previously been encountered 38 and would be the most likely source of infection. Importantly, this phenomenon provides a novel 39 means to therapeutically target innate immune effector cells to sites of specific disease localization 40 to potentially treat a wide spectrum of pathologies, including cancer, infection, and chronic 41 inflammatory disorders. 42 43 AUTHOR SUMMARY 44Vaccines that target adaptive immune memory have revolutionized medicine. This study 45 describes a novel strategy that works as a modified innate immune "vaccine" that exploits the 3 46 trained response of innate immune effector cells to clear pathology in a specific tissue site. 47Unlike memory of the adaptive immune system, which functions like a lock and key, innate 48 immune memory is more akin to a reflex response -like experienced muscle or neural cells that 49 are changed by a stimulus to respond more efficiently upon re-exposure. This change in behavior 50 through experience is the definition of learning. Our study suggests that this innate immune 51 learning occurs at different levels. Emergency hematopoiesis trains new innate immune cells in 52 the bone marrow to respond quickly and effectively to a non-specific threat; whereas, pathogen-53 specific training occurs at sites where cells making up the immunologic niche have had 54 interactions with a particular pathogen and have been trained to respond more robustly to it upon 55 re-presentation in the context of a danger signal. The speed with which new immune cells are 56 trained in the bone marrow in response to an imminent microbial threat and their subsequent 57 recruitment to the target organ site where that microbe typically resides suggests there are ways 58 the immune system communicates to coordinate this rapid response that are yet to be fully ...