Project Information

Project 1

PI: Dr. Chuanlin Ding
Mentors: Drs. Jun Yan and Haribabu Bodduluri
Project Title: Ongoing Inflammation following Chemotherapy Induces Immunosuppression

Project Summary

Conventional chemotherapy has been thought to act through the direct killing of tumor cells. However, accumulating evidence indicates that immune competence is crucially required for chemotherapy efficacy. It is expected that loss of this immunity during chemotherapy has a negative effect on its efficacy. Therefore, the impact of chemotherapy on anti-tumor immunity needs further investigation in order to rationally design combinatorial regimens for conventional chemotherapy.

In the preliminary studies, we have demonstrated that repeated chemodrug gemcitabine (GEM) treatment promoted the expansion and differentiation of immunosuppressive Ly6Chigh monocytic-MDSC (M-MDSC). Tumor-derived soluble factors, such as GM-CSF and soluble ICAM-1(sICAM-1), were up-regulated upon chemo-drug treatment. In tumor-free naïve mice, GEM treatment induced the immunosuppressive activity of Ly6Chigh myeloid cells in the bone marrow (BM). The chemokine CX3CL1 and its receptor CX3CR1 expression levels were elevated in the BM. Higher levels of mitochondrial reactive oxygen species (mtROS) were also observed in tumor cells and BM stromal cells following chemotherapy. Furthermore, chemotherapy induced NF-κB activation leading to the hyperproduction of GM-CSF by tumor cells. Based on these preliminary data, we hypothesize that chemotherapy enhances the production of mtROS in tumor cells and BM stromal cells, which increases the expressions of GM-CSF and sICAM-1 as well as CX3CL1 leading to the enhanced immunosuppression of M-MDSC in the TME. These hypotheses will be addressed by two Specific Aims. Aim 1 defines the roles of GM-CSF and sICAM-1 in chemotherapy-induced differentiation of immunosuppressive Ly6Chigh myeloid cells and the mechanisms underlying mtROS and upregulation of GM-CSF and sICAM-1 in tumor cells; Aim 2 determines the mechanisms by which host cell-derived chemokine CX3CL1 regulates the accumulation and immunosuppressive function of inflammatory Ly6Chigh myeloid cells in the BM. The findings from these studies will allow us to gain a better understanding the underlying mechanisms by which ongoing inflammation following multi-dose clinical regimens of chemotherapy modulates anti-tumor immunity, and rationally design a novel therapeutic approach by combining chemotherapy with mitochondria-targeted antioxidants for cancer treatment.

Project 2

PI: Dr. Qingsheng Li
Mentors: Drs. Nejat Egilmez and Jason Chesney
Project Title: Mechanisms of Resistance to Immunotherapy in NSCLC

Project Summary

Despite having been approved as first and second line therapy for non-small cell lung cancer (NSCLC), anti-PD-1 antibodies still fail in a substantial proportion of lung cancer patients. The mechanism that underlies the failure of anti-PD-1 therapy in the majority of NSCLC patients is not yet fully understood. We have discovered that, in the anti-PD-1-resistant LSL-KrasG12D murine lung adenocarcinoma mouse model, treatment induces a T-cell activation profile that favors Th17/γδT17 reinvigoration over CD8+ T cell activation. In contrast, when administered in conjunction with an anti-IL-17 neutralizing antibody, anti-PD-1 treatment results in a dramatic enhancement of CD8+ T-cell cytotoxicity with near-complete eradication of established disease.  These findings provide the premise for our central hypothesis that in NSCLC, the failure of anti-PD-1 is, at least in part, due to reinvigoration of PD-1+ type 17 T cells (Th17/γδT17), which actively undermine anti-PD-1-mediated restoration of cytotoxic function in CD8+ T-cells.  Based on additional murine data, we are also advancing the extended hypothesis that the severity of pre-existing T17 activity in the neoplastic lung is determined by commensal bacteria and that the lung microbiota signature can ultimately predict responsiveness to anti-PD-1 therapy.  The goal of this proposal is to demonstrate the relevance of these findings to human prior to initiating an R01 application. Specifically, in Aim 1, we will establish whether intrinsic lung T17/CTL ratio is predictive of anti-PD-1 responsiveness in NSCLC patients independent of neoantigen burden. In Aim 2 we will determine whether specific human lung microbiota, individually or in defined combinations, drive the ontogeny of intrinsic T17 immunity and ultimately resistance to ICI therapy.  The proposed study is conceptually impactful as it addresses an important clinical conundrum; is mechanistically novel; and has translational relevance since it introduces therapeutic/prognostic approaches that can rapidly move to the clinic.

Project 3

PI: Dr. Corey T. Watson
Mentors: Drs. Jason Chesney and Jun Yan
Project Title: Defining Tumor-infiltrating B Cell Signatures associated with T Cell-mediated Antitumor Immunity in Human Lung Adenocarcinoma

Project Summary

Lung cancers are the most common malignancies and are the leading cause of cancer-related deaths worldwide. Immunotherapies are transforming treatment regimes, and trials conducted in lung cancer have already demonstrated improvements in long-term survival outcomes. However, existing therapies are not effective in all patients, stressing a need to better characterize the complex molecular and immunological processes associated with treatment responsiveness and disease progression. Although T cells have been the primary target of immunotherapies in lung cancer, there is a growing appreciation that T cell-mediated anti-tumor immunity can be influenced by actions of other immune cells within the tumor microenvironment (TME). Tumor-infiltrating (TI) B cells have been shown to have dual roles in tumor progression generally, but in non-small cell lung cancers (NSCLC), specifically adenocarcinomas (LUAD), particular B cell subsets have been shown to both promote T cell anti-tumor responses and positively impact long-term survival outcomes. Indications of a role for specific antibody (Ab) responses in LUAD have also recently been reported, including evidence of focused tumor antigen-specific responses. However, characterizations of anti-tumor B cells and their functional signatures have been limited by the study of only a small number of pre-selected surface markers in relatively small numbers of patients. Nonetheless, it is evident that B cell-mediated roles in LUAD tumor progression are variable among patients, and indicates that a more comprehensive and integrated characterization of TI B cell phenotypic variation and the associated effects on the anti-tumor T cell response has great potential to inform our understanding of disease progression, as well as the development of novel, potentially personalized, therapies. The overall goal of this proposal is to define TI B cell signatures that are associated with the T cell-mediated anti-tumor response in human lung cancer. To achieve this goal, we will leverage several cutting edge techniques to first comprehensively profile lymphocytes (B and T cells) and myeloid cells in tumor and paired normal tissues from a large cohort of early-stage LUAD patients, including the first pairing of this type of data with Ab repertoire sequencing as a means to interrogate critical functional Ab response signatures in LUAD B cells. Importantly, the single-cell profiling approach proposed will leverage B cell markers already determined to be associated with long-term LUAD survival outcomes, so that distinct functional B cell profiles and their associations with TI T cells and myeloid cells can be identified specifically in the context of disease progression (Aim 1). These large-scale statistical associations will be validated and then serve as a framework for conducting functional in vitro culture and serum-based analyses to assess whether prognostically favorable B cell subsets identified have distinct functional phenotypes, associate with tumor antigen-specific Ab responses, and have differential effects on T cell activation and effector function (Aim 2). Successful completion of this project will facilitate novel discovery and biomarkers critical for the development of novel therapeutics in human lung cancer.

Project 4

PI: Dr. Kavitha Yaddanapudi
Mentors: Drs. Robert A. Mitchell and Huang-ge Zhang
Project Title: Overcoming Resistance to Cancer Immunotherapy by Targeting MDSC-derived Adenosine

Project Summary

Lung cancer is a prevalent disease and consumes many lives every year. Cancer immunotherapy using immune checkpoint inhibitors (ICIs; e.g. anti-PD-1, anti-CTLA-4 antibodies) has revolutionized the treatment of metastatic lung cancer, resulting in long-term complete responses for many patients. Nevertheless, there remains an urgent need for new strategies because not all patients respond to ICIs; moreover, resistance can occur in those that do. Myeloid-derived suppressor cells (MDSCs), in particular, monocytic MDSCs (M-MDSCs) are potent immunosuppressive innate immune cells that actively inhibit CD8+ T cell tumor homing and activation. Since M-MDSC levels are elevated in multiple human cancers and correlate with decreased patient survival, we postulate that these cells contribute to anti-PD-1 resistance. The purine nucleoside, adenosine, is produced in copious amounts within the tumor microenvironment (TME), where it serves to suppress the immune system and promote tumor growth. There is evidence to suggest that overproduction of adenosine can mediate resistance to ICIs. Immune suppressive adenosine is produced via the enzymatic conversion of extracellular AMP by the cell surface enzyme, CD73 (ecto-5¢-nucleotidase; AMP ® adenosine). Our preliminary studies demonstrate that tumor cell-derived prostaglandin E2 (PGE2) maintains M-MDSC suppressive activity, in large part, by directly inducing cell surface CD73 expression via a novel PGE2→cAMP→CREB/STAT3 pathway leading to increased immune suppressive adenosine within the TME. The overall hypothesis of this proposal is that tumor cell-derived PGE2 dictates CD73 expression in M-MDSCs leading to substantial increases in adenosine-dependent inhibition of anti-tumor CD8+ T cell activation resulting, ultimately, in anti-PD-1 immunotherapeutic resistanceA major goal of this proposal is to test the anti-tumor efficacy of a novel cancer immunotherapy involving systemic administration of adenosine deaminase (ADA)—an enzyme that irreversibly converts adenosine into inosine, a non-immunosuppresive nucleoside. A pegylated version of bovine ADA (PEG-ADA) is already FDA-approved for use as an enzyme replacement therapy in children with ADA-associated severe combined immunodeficiency (ADA-SCID). We hypothesize that depletion of adenosine-mediated T cell immune suppression by PEG-ADA sensitizes tumors to PD-1 inhibitor therapy and improves clinical outcomes for NSCLC patients. To fulfill the stated objectives, the following aims are proposed: 1) Delineate the signaling pathway and molecular mechanisms by which PGE2 induces CD73 expression in M-MDSCs; 2)Determine whether inhibition of the PGE2→cAMP→CREB/STAT3→CD73→adenosine pathway attenuates anti-PD-1 resistance in a mouse model of lung cancer; and 3) Validate PGE2 → CD73+ M-MDSC → adenosine mediated anti-PD-1 resistance pathway in lung cancer patients receiving pembrolizumab therapy. Our proposed study will provide important insights towards developing a safe and novel immunotherapy to attenuate ICI resistance in lung cancer patients.