Comparison between the analytical sensitivity and clinical performance of two cobas SARS-CoV-2 tests based on high-throughput and point-of-care systems.

Objectives: This study examined analytical sensitivity, specificity, and the clinical performance in detecting SARS-CoV-2 of the Cobas SARS-CoV-2 Test based on the high-throughput Cobas 6800 system and the Cobas SARS-CoV-2 & Flu A/B Test based on the point-of-care cobas Liat system. Methods: The commercial reagents containing SARS-CoV-2 RNA subgenomes were diluted for assessing the sensitivity of the RT-qPCR assay. 385 nasopharyngeal swab specimens taken from contacts of COVID-19 cases were tested for the SARS-CoV-2 detection with both Cobas SARS-CoV-2 Tests. Results: In analytical sensitivity assays, the Cobas SARS-CoV-2 & Flu A/B Test on the Liat system had a lower limit of detection (12.5-25 copies/mL) than the cobas SARS-CoV-2 Test on the cobas 6800 system (25-50 copies/mL). In clinical performance assays, the cobas SARS-CoV-2 Test demonstrated 89.36% (42 out of 47) PPA (positive percent agreement) and 98.82% (334 out of 338) NPA (negative percent agreement) compared to the results of the Cobas SARS-CoV-2 & Flu A/B test. Among five discordant specimens, four had the positive result of the cobas SARS-CoV-2 test, but the negative result of the cobas SARS-CoV-2 & Flu A/B Test. Moreover, these discordant specimens had the Ct values of greater than 33 for the cobas SARS-CoV-2 Test, implying a very small number of virions in the samples. Remarkably, four specimens with a presumptive positive result of the cobas SARS-CoV-2 test had been confirmed by the Cobas SARS-CoV-2 & Flu A/B Test. Next, the scatter plots of the Ct values showed a highly positive correlation between cobas SARS-CoV-2 & Flu A/B Test and the cobas SARS-CoV-2 Test (R-squared value = 0.954-0.962). Conclusions: Both SARS-CoV2 tests of the cobas 6800 and Liat systems produce reliable high throughput and point-of-care assays respectively for the early virus detection and the personal care decision-making during COVID-19 pandemic.

Clinical application of liquid biopsy in cancer patients.

BACKGROUND: This study was to determine the prevalence and clinical significance of clonal hematopoiesis (CH)-related variants, and somatic and germline mutations in cancer patients and healthy individuals. METHODS: We performed next-generation sequencing of 275 cancer-related genes be-tween plasma and white blood cells in 92 cancer patients and 47 controls without cancer. Blood samples were recruited from May 2017 to July 2021, and blood cancer patients were excluded. For all statistical analysis in this study, p < 0.05 was considered statistically significant. RESULTS: Overall, 38.04% of patients and 46.81% of controls harbored at least one CH-related mutation in plasma cell-free DNA. Based on our results, older cancer patients exhibited a CH phenomenon more frequently than younger patients (p = 0.0024). A total of 39 somatic pathogenic (P)/likely pathogenic (LP) mutations were identified in 17 genes in 21 of 92 patients. We found that the presence of P/LP variants in cancer-related gene predicted shorter overall survival (OS) (p = 0.001). Multivariate analysis adjusted for CH-related mutations, germline mutations, and tumor stage, also indicated that somatic mutations correlated significantly with OS (p = 0.022). Moreover, the frequency of a germline P/LP variant was that of seven of 92 individuals in the cancer group and one of 42 individuals in the control group. CONCLUSIONS: We characterized the CH-related variants, and somatic and germline mutations in cancer patients and healthy individuals, and the results have important clinical significance.