Periodic Reporting for period 4 - CAN-IT-BARRIERS (Disruption of systemic and microenvironmental barriers to immunotherapy of antigenic tumors)
Reporting period: 2024-07-01 to 2024-12-31
To illuminate the mechanisms of intra-tumoral and systemic immune barriers that limit the efficacy of ground-breaking immunotherapies, we used immunocompetent genetically engineered mouse cancer models of cancer (GEMM), enabling the investigation of susceptibility and resistance to therapies, in particular those based on harnessing the body’s immune system to attack and destroy tumors. By elucidating the mechanistic bases of immuno-evasive barriers based on corrupted cells and regulatory signals, our goal was to develop the means to break down these barriers and reprogram the cells implicated in immuno-evasion into ones that instead contribute to tumor immunity. We investigated these questions using several distinctive GEMMs (developing pancreatic cancer, melanoma, or human papillomavirus (HPV16) induced cervical cancer), each of which phenocopies the human disease it is modeling, in terms of tumor development, histopathology, and response to therapy, notably in their resistance to immunotherapies.
One line of investigation (Strategic Goals 1,2&4) used a GEMM that targets the expression of the HPV16 oncogenes to basal keratinocytes, eliciting the multistep development of invasive cervical carcinomas in females, as well as dysplasias of the skin in males and females,. The dysplastic and cancerous tissues elicit systemic immuno-suppression (SIS) of the generation and expansion of tumor-antigen-specific T cells, mediated by neutrophils, which is operative in the lymphoid organs as well as in dysplasias and tumors. We have discovered the mechanistic basis, which involves the expression in HPV16-expressing keratinocytes and secretion into the circulation of three members of the IL1 cytokine superfamily, which instructs the bone marrow to produce abundant quantities of demonstrably immunosuppressive neutrophils that then migrate to the spleen and tumor. Translational studies implicate the same mechanism in human cervical cancer. A pan-IL1 inhibitor shuts down the expansion of these immunosuppressive neutrophils, abrogating the SIS, and importantly unlocking an otherwise ineffectual therapeutic vaccine based on the HPV16 E7 oncoprotein. The combination produces significant therapeutic benefit in mouse models, which can be further extended by blocking the CTLA4 immune checkpoint. A manuscript describing the results is being readied for submission to a prominent journal, and the results are being presented at international cancer conferences.
A second line of investigation (Strategic Goals 3&4) involves models of pancreatic neuroendocrine cancer and melanoma and has implicated tumor-associated macrophages (TAMs) in stimulating tumor development and therapeutic resistance mechanisms following standard-of-care therapies. We have found that TAMs are a significant component of both mouse models, being predominantly biased toward a pro-tumoral “M2-like” phenotype. Furthermore, the TAMs exhibit multifaceted capabilities to inhibit the activity of cytotoxic T cells, suggesting that these TAMs play a significant role in evading anti-tumoral immune responses in the tumor microenvironment TME and are therefore a critical component of the intrinsic resistance to immunotherapies. Moreover, we have identified the angiogenic tumor neo-vasculature in pancreatic cancer as a significant barrier to T cell infiltration, one that we are seeking to reprogram it to become a gateway for productive immune attack. These data highlight the instrumental roles of tumor-associated macrophages and tumor vasculature as key components of the immuno-evasive barrier in solid tumors, ones that present new therapeutic vulnerabilities with the potential to elicit more effective anti-tumor immune responses. Translational studies implicate similar mechanisms in the cognate human cancers. A publication in Immunity (PMID: 36630914) describes the reprogramming of the immunosuppressive TME, and in particular of tumor-associated macrophages (TAMs) and endothelial cells, to enable an efficacious T cell attack, using an innovative combination of a synthetic immuno-cytokine (PD1-IL2v) and an immune checkpoint inhibitor (anti-PD-L1). A second manuscript, to be submitted in the coming months, describes the reprogramming of TAMs in melanomas with three distinctive mechanism-targeted drugs that convert TAMs from being tumor-promoting to instead enhancing the efficacy of standard of care therapies. The results will also be presented in international cancer conferences.
A second line of investigation (Strategic Goals 3&4) involves models of pancreatic neuroendocrine cancer and melanoma and has implicated tumor-associated macrophages (TAMs) in stimulating tumor development and therapeutic resistance mechanisms following standard-of-care therapies. We have found that TAMs are a significant component of both mouse models, being predominantly biased toward a pro-tumoral “M2-like” phenotype. Furthermore, the TAMs exhibit multifaceted capabilities to inhibit the activity of cytotoxic T cells, suggesting that these TAMs play a significant role in evading anti-tumoral immune responses in the tumor microenvironment TME and are therefore a critical component of the intrinsic resistance to immunotherapies. Moreover, we have identified the angiogenic tumor neo-vasculature in pancreatic cancer as a significant barrier to T cell infiltration, one that we are seeking to reprogram it to become a gateway for productive immune attack. These data highlight the instrumental roles of tumor-associated macrophages and tumor vasculature as key components of the immuno-evasive barrier in solid tumors, ones that present new therapeutic vulnerabilities with the potential to elicit more effective anti-tumor immune responses. Translational studies implicate similar mechanisms in the cognate human cancers. A publication in Immunity (PMID: 36630914) describes the reprogramming of the immunosuppressive TME, and in particular of tumor-associated macrophages (TAMs) and endothelial cells, to enable an efficacious T cell attack, using an innovative combination of a synthetic immuno-cytokine (PD1-IL2v) and an immune checkpoint inhibitor (anti-PD-L1). A second manuscript, to be submitted in the coming months, describes the reprogramming of TAMs in melanomas with three distinctive mechanism-targeted drugs that convert TAMs from being tumor-promoting to instead enhancing the efficacy of standard of care therapies. The results will also be presented in international cancer conferences.
Our multi-faceted project will illuminate new aspects of the biology of tumors and their resistance to immunotherapies. We are using refined GEMMs of intra-tumoral (pancreatic cancer and melanoma models) and systemic (HPV+ model) immunosuppression as a platform to characterize and identify actionable targets. We have determined that reprogramming the suppressive TME – namely the myeloid cells (neutrophils and TAMs) and the gatekeeping tumor vasculature - toward a more immune-permissive state would be the basis of a novel type of combinatorial therapy. Moreover, we developed state-of-the-art bioinformatic datasets to decipher the mechanisms of intra-tumoral and systemic immune barriers. Ultimately, we will compare and contrast the targets identified – cells and/or secretome - to perform combinatorial trials for in-depth immunological characterization. To further investigate the systemic immune suppression in human cervical cancer patients, we established several collaborations to characterize biopsies from HPV-driven cancer patients and melanoma patients. We are investigating the presence of immunosuppressive barriers and remodeling of the TME upon treatment and resistance to therapy. Furthermore, as suggested by our data in the HPV+ mouse model, namely that the SIS acts via an immunosuppressive secretome within the bloodstream, we plan to perform proteomic analyses of plasma samples obtained from patients. These analyses will shed light on the degree of systemic immune suppression operating in human cancers and will potentially also lead to the identification of biomarkers to predict the response to immunotherapies. The ultimate goal is to decipher the mechanisms of -local and systemic- immunosuppression, identify actionable targets to set up novel therapeutic strategies in our preclinical models, and translate the findings into better treatments for cancer patients.