Oxaliplatin (OXP) can change tumor microenvironment from immune-suppressive toward the immune-favorable condition. Almost all of the antitumor agents cannot totally cure cancer as monotherapy. So the current focus of cancer research became combining therapy using different treatment regimen, especially chemotherapy with checkpoint blockers. In this study, we assessed the activity of combining regimen using anti-PD-L1 with OXP in CT26 tumor-bearing BALB/c mice. We further analyzed the immune cell phenotypes in tumor site, lymph nodes, and spleen by flow cytometry analysis. Our study showed that combination therapy with OXP and anti-PD-L1 significantly increased survival in vivo and inhibited tumor growth of tumor-bearing mice. Inconsistent with better antitumor activity, our combination therapy led to an increase in tumor-infiltrating activated CD8+ T cells. In draining lymph nodes and spleen, regulatory T cells decreased significantly. Mice receiving either anti-PD-L1 or OXP alone had a larger tumor and lower survival rate in comparison with combination therapy receiving group. The time and order of administration of each component of the combination therapy affected antitumor response. K E Y W O R D Santi-PD-L1, cancer, chemotherapy, combination therapy, immunotherapy

COVID-19 currently is the main cause of the severe acute respiratory disease and fatal outcomes in human beings worldwide. Several genes are used as targets for the detection of SARS-CoV-2, including the RDRP, N, and E genes. The present study aimed to determine the RDRP, N, and E genes expressions of SARS-CoV- 2 in clinical samples. For this purpose, 100 SARS-CoV-2 positive samples were collected from diagnostic laboratories of Mazandaran province, Iran. After RNA extraction, the real-time reverse transcription PCR (real-time RT-PCR) assay was performed for differential gene expressions’ analysis of N, E, and RDRP. The threshold cycle (Ct) values for N, RDRP, and E targets of 100 clinical samples for identifying SARS-CoV-2 were then evaluated using quantitative real-time PCR (qRT-PCR). This result suggests N gene as a potential target for the detection of the SARS-CoV‐2, since it was observed to be highly expressed in the nasopharyngeal or oropharynges of COVID-19 patients (P < 0.0001). Herein, we showed that SARS-CoV- 2 genes were differentially expressed in the host cells. Therefore, to reduce obtaining false negative results and to increase the sensitivity of the available diagnostic tests, the target genes should be carefully selected based on the most expressed genes in the cells.

SARS-CoV-2(COVID-19) currently is the main cause of the severe acute respiratory disease and fatal outcomes in human beings worldwide. Several genes are used as targets for the detection of SARS-CoV-2, including the RDRP, N, and E genes. The present study aimed to determine the RDRP, N, and E genes expressions of SARS-CoV- 2 in clinical samples. For this purpose, 100 SARS-CoV-2 positive samples were collected from diagnostic laboratories of Mazandaran province, Iran. After RNA extraction, the real time RT-PCR assay was performed for differential gene expressions’ analysis of N, E, and RDRP. The CT values for N, RDRP, and E targets of 100 clinical samples for identifying SARS-CoV-2 were then evaluated using qRT-PCR. This result suggests N gene as a potential target for the detection of the SARS‐CoV‐2, since it was observed to be highly expressed in the nasopharyngeal or oropharynges of COVID-19 patients (P < 0.0001). Herein, we showed that SARS-CoV- 2 genes were differentially expressed in the host cells. Therefore, to reduce obtaining false negative results and to increase the sensitivity of the available diagnostic tests, the target genes should be carefully selected based on the most expressed genes in the cells.