Priming stroma with a vitamin D analog to optimize viroimmunotherapy for pancreatic cancer

Culprits of PDAC resistance to gemcitabine and immune checkpoint inhibitor: Tumour microenvironment components

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive and lethal cancer with a dismal five-year survival rate of 11%. Despite remarkable advancements in cancer therapeutics, PDAC patients rarely benefit from it due to insurmountable treatment resistance. Notably, PDAC is pathologically characterized by an extensive desmoplastic reaction and an extremely immunosuppressive tumour microenvironment (TME). The PDAC TME consists of cell components (e.g., tumour, immune and stromal cells) and noncellular components (e.g., extracellular matrix), exhibiting high complexity and their interplay resulting in resistance to chemotherapeutics and immune checkpoint inhibitors. In our review, we shed light on how crosstalk of complex environmental components modulates PDAC drug resistance, and we summarize related clinical trials. Moreover, we extend our discussion on TME exploration and exosome analysis, providing new insights into clinical applications, including personalized medicine, disease monitoring and drug carriers.

Reprogramming the tumor microenvironment to improve the efficacy of cancer immunotherapies

The immunotherapeutic approaches based on checkpoint inhibitors, tumor vaccination, immune cell-based therapy, and cytokines were developed to engage the patient's immune system against cancer and better survival of them. While potent, however, preclinical and clinical data have identified that abnormalities in the tumor microenvironment (TME) can affect the efficacy of immunotherapies in some cancers. It is therefore imperative to develop new therapeutic interventions that will enable to overcome tumor-supportive TME and restrain anti-tumor immunity in patients that acquire resistance to current immunotherapies. Therefore, recognition of the essential nature of the tolerogenic TME may lead to a shift from the immune-suppressive TME to an immune-stimulating phenotype. Here, we review the composition of the TME and its effect on tumor immunoediting and then present how targeted monotherapy or combination therapies can be employed for reprogramming educated TME to improve current immunotherapies outcomes or elucidate potential therapeutic targets.