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Simple Summary: The introduction of immune checkpoint inhibitors (ICI) in 2011 revolutionized the management of many solid cancers and hematological malignancies. However, there are concerns regarding the use of ICI in the era of COVID-19. We present currently available information on the pros and cons of using ICI in cancer patients with respect to the risk of acquiring an infection by SARS-CoV2 and mortality from COVID-19. By means of the present paper, clinicians and researchers may update their knowledge on a highly topical clinical question—is the use of ICI in cancer patients with SARS-CoV2 infection harmful with respect to COVID-19 outcome? Whether cancer patients receiving immune checkpoint inhibitors (ICI) are at an increased risk of severe infection and mortality during the corona pandemic is a hotly debated topic that will continue to evolve. Here, we summarize and discuss current studies regarding COVID-19 and anti-cancer treatment with an emphasis on ICI. Importantly, several lines of evidence suggest that patients currently treated with ICI do not display an increased vulnerability to infection with SARS-CoV-2. Data regarding morbidity and mortality associated with COVID-19 in cancer patients receiving ICI are less clear and often conflicting. Although mostly based on experimental data, it is possible that ICI can promote the exacerbated immune response associated with adverse outcome in COVID-19 patients. On the other hand, mounting evidence suggests that ICI might even be useful in the treatment of viral infections by preventing or ameliorating T cell exhaustion. In this context, the right timing of treatment might be essential. Nevertheless, some cancer patients treated with ICI experience autoimmune-related side effects that require the use of immunosuppressive therapies, which in turn may promote a severe course of infection with SARS-CoV-2. Although there is clear evidence that withholding ICI will have more serious consequences, further studies are urgently needed in to better evaluate the effects of ICI in patients with COVID-19 and the use of ICI during the corona pandemic in general. [ABSTRACT FROM AUTHOR]

The life span of dendritic cells (DCs) can become short following induced activation, which is associated with metabolic transition due to the regulation of mechanistic target of rapamycin (mTOR). The purpose of this study was to investigate the potential of inhibiting mTOR to modulate DC functions for elevating the anti-tumor effects of DNA vaccines. Therefore, the influences of various inhibitors of mTOR (mTORi) on the expressions of DC maturation markers, the abilities of antigen presenting and processing of BMM-derived DCs and the tumor killing effects of E7-specific CD8+ T lymphocytes activated by BMM-derived DCs were in vitro examined. The anti-tumor effects of connective tissue growth factor (CTGF)/E7 DNA vaccine and/or mTORi were also in vivo analyzed. In our study, suppressive effects of mTORi on the DC maturation markers expressed on BMMCs could be reversed. The mTORi-treated mature BMM-derived DCs tended to be non-apoptotic. These mTORi-treated BMM-derived DCs could have better antigen presenting and processing abilities. The E7-specific cytotoxic CD8+ T lymphocytes could have more potent tumoricidal activity following activation of mTORi-treated BMM-derived DCs. For tumor-bearing mice, those treated with CTGF/E7 DNA vaccine and mTORi indeed can have higher percentages of mature DCs in the TME, better disease control and longer survivals. Consequently, application of mTORi can be a pharmacological approach for temporally increasing life span, antigen presenting and antigen processing of DCs to strengthen the therapeutic outcome of cancer immunotherapy. [ABSTRACT FROM AUTHOR]