Abbott Japan LLC

The IgG antibody titer against SARS-CoV-2 receptor binding protein (RBD) after mRNA vaccine were compared between those with and without previous infection (PI) for up to 48 weeks. Though sustained higher IgG-RBD were observed in the PI group after two doses of vaccines, both groups benefited from the booster shots of the third vaccine. This data supports the necessity of the booster shots to those with PI.

Exact comprehension of the prevalence of SARS-CoV-2 infection is essential for the preventive measures. In the clinical settings, however, patients infected with SARS-CoV-2 may not be fully detected by PCR. In the long-term prevalence study, cut-off of IgG assay may not be appropriate due to waning IgG titer.

24 PCR-negative subjects suspected of COVID-19 were categorized into cohorts termed "presumed COVID-19 positive" and "presumed COVID-19 negative" by chest CT images. IgG against nucleocapsid protein of SARS-CoV-2 (IgG (N)) and IgG against receptor biding domain of SARS-CoV-2 (IgG (RBD)) were measured in sera of the subjects and the concordance with the cohort categorization was assessed by receiver operating characteristics (ROC) analyses.

Area under the curves (AUC's) by the ROC analyses with the 24 subjects were 0.982 with IgG (N) and 0.854 with IgG (RBD). Even when we excluded the subjects whose initial PCR was performed after five days from symptom onset, the AUC's were 0.967 with IgG (N) and 0.800 with IgG (RBD). The ROC analysis indicated 0.2 S/C as the optimum cut-off forIgG (N).

Both IgG (N) and IgG (RBD) titers were significantly elevated in subjects whose PCR never showed positive but suggestive of SARS-CoV-2 infection, which indicated the necessity of serological tests in complementing the shortcomings of PCR. For a long-term prevalence study, a cut-off lower than the one used in the ongoing infection phase (e.g. 0.2 S/C vs. 1.4 S/C) was indicated to be more appropriate for IgG (N).

Emerging data suggested that liquid biopsy such as detection of circulating tumor cells (CTCs) and cell-free tumor DNA analysis augments the management of patients with urothelial cancer (UC). We presented our pilot experience of liquid biopsy using the Ion Torrent platform to detect CTCs and genomic alterations in UC.

Blood or urine samples from 16 patients were subjected to CTC and plasma/urine cell-free tumor DNA isolation for next generation sequencing (NGS) using the Ion S5 system to detect mutations among 50 oncogenes on the Ion AmpliSeq Cancer Hotspot Panel.

The Ion Torrent platform detected a higher number of CTCs than those in previous studies using the CellSearchTM system. Overall, mutations were detected in 13/16 (81.3%) patients with a median number of 18 (range 12–25). NGS isolated 17 hotspot mutations from 11 genes and 41 novel genomic alterations from 24 genes, some of which are supposed to be clinically actionable.

The Ion Torrent platform efficiently detected CTCs compared with previous reports. NGS with the present system also allowed for detection of gene alterations which are likely to be therapeutic targets and provided an attractive tool to guide personalized therapy for patients with advanced UC.