The use of nano-enabled chemotherapy to trigger an immune response to pancreatic ductal adenocarcinoma (PDAC) introduces a novel approach for overcoming robust barriers to immunotherapy, including poor immunogenicity, low neoantigen burden, stromal interference (?T-cell exclusion?), overexpression of indoleamine 2,3-dioxygenase (IDO-1), and the immune privileged environment of the liver favoring metastatic spread. Our preliminary data show that lipid-bilayer coated mesoporous silica nanoparticles (silicasomes) provide an effective platform for inducing immunogenic cell death (ICD) by delivering prescreened chemotherapeutic agents to the PDAC site. ICD promotes the presentation of endogenous tumor antigens cells, raising the hypothesis that ICD offers a promising endogenous vaccination approach to generate a ?hot? tumor microenvironment (TME) that can be propagated by co-delivery of drugs interfering in regionally overexpressed immunosuppressive pathways. These pathways can be targeted by inhibitors of IDO-1, CXCR4 (T-cell exclusion) and glycogen synthase kinase 3 (which controls PD-1 expression). We also propose that metastatic spread can be reduced by ICD-induced memory T-cells and delivery of ?stimulator of interferon genes? (STING) agonists to tolerogenic antigen presenting cells in the liver. The long-term goal of our interdisciplinary efforts is to develop a chemo-immunotherapy platform for delivery of ICD stimuli by the silicasome contemporaneous with inhibitors of immune checkpoint and T-cell exclusion pathways (CXCR4). The objectives include the use of innovative drug loading and cholesterol-conjugated prodrugs to synthesize silicasomes that can be used to obtain the best synergy between ICD stimuli and inhibitors of immunosuppressive pathways in orthotopic and genetic engineered PDAC models. This requires research discovery into the mechanistic basis of synergy between ICD and regional immune escape pathways. We will use an integrin-targeting, tumor-penetrating iRGD peptide to enhance drug delivery by a transcytosis pathway. We will also construct polymeric nanocarriers to deliver STING agonists for preventing metastatic spread to the liver. The rationale is that the use of an ICD approach to generate a ?hot? tumor environment will facilitate combination immunotherapy with improvement of PDAC mortality. We plan to test our hypothesis by pursuing the following specific aims:
Aim 1 : To develop a nano-enabled chemo-immunotherapy platform for PDAC that utilizes an endogenous (ICD-mediated) treatment approach plus interference in regionally overexpressed immune checkpoint pathways to generate a ?hot? tumor environment.
Aim 2 : To enhance the immunotherapy impact of the ICD platform by using integrin-targeting, tumor-penetrating iRGD peptides and developing a silicasome that interferes in T-cell exclusion in the stroma through the delivery of CXCR4 inhibitors.
Aim #3 : To reprogram the immune suppressive effects of liver APC by STING nanoparticles that promote eradication of PDAC metastases by the memory T-cells generated by ICD-inducing silicasomes.
In spite of the major success of immune checkpoint inhibitory (ICI) antibodies capable of triggering immune responses to solid cancers, pancreatic ductal adenocarcinoma (PDAC) responds poorly to this intervention due to an immune depleted or ?cold? tumor microenvironment. In this application, we will develop a series of nanocarriers to deliver chemotherapeutic drugs to induce ?immunogenic cell death? (ICD), which is capable of creating a ?hot? tumor environment that can be further exploited to obtain a sustained immune response. The cornerstone of the PDAC immunotherapy platform is a silicasome nanocarrier, which has the ability to deliver ICD stimuli in combination with synergistic small molecule inhibitors that interfere in local immune suppressive pathways.
