Background: Cancer cell line-derived feeder cells enhance natural killer (NK) cell expansion; however, concerns regarding viable residual feeder cells in the final product limit their use. Evidence supporting the safety of NK-sensitive K562-based feeders, even when irradiated, is scarce. We optimized an NK cell expansion protocol using genetically engineered K562-mbIL-18/-21 (GE-K562) feeder cells and clinical-grade media and confirmed the absence of residual feeder cells. Methods: NK cell expansion efficiency was compared between feeder-free and feederbased systems using CTS NK-Xpander Medium. To achieve optimal NK expansion, various peripheral blood mononuclear cell (PBMC)-to-feeder ratios and re-stimulation frequencies were tested over 21 days. Flow cytometry and BCR::ABL1 quantitative reverse transcription PCR (RT-qPCR) were used to confirm the absence of feeder cells in the final NK cell product. Results: Feeder-based systems showed superior NK cell fold expansion compared with that of feeder-free systems. Among feeder-based conditions, NK cells expanded 5,224-fold at a 2:1 PBMC-to-feeder ratio after 3 weeks, relative to 1,450-fold at a 6:1 ratio (P < 0.05).Re-stimulation on days 7 and 14 further increased expansion up to 261,457-fold. Irradiated feeder cells showed no proliferation and were eliminated within 3–6 days. On day 21, flow cytometry and BCR::ABL1 RT-qPCR results confirmed the absence of residual feeder cells. Conclusions Our optimized NK cell expansion protocol using irradiated GE-K562 feeder cells and clinical-grade media offers a safe and scalable approach to generating large numbers of NK cells, supporting its potential use in clinical immunotherapy applications.

Purpose: Immune checkpoint inhibitor plus chemotherapy is the standard first-line treatment for advanced gastric cancer; however, predictive biomarkers for optimal patient selection remain unsatisfactory. This study was aimed at evaluating the predictive value of tumor mutational burden (TMB) and insertion/deletion (Indel) rate in patients with gastric cancer treated with nivolumab plus chemotherapy. Materials and Methods: This retrospective study included 132 patients with gastric cancer treated with first-line nivolumab plus chemotherapy and 185 patients treated with chemotherapy alone, all of whom had next-generation sequencing data available. The TMB and Indel cut-offs were set at 15.63 mutations per megabase and 18.19%, respectively, as determined based on their ability to best distinguish progression-free survival (PFS) among the patients who received nivolumab plus chemotherapy. Results: PFS was favorable for nivolumab and chemotherapy than for chemotherapy alone in both the high and low TMB groups; nevertheless, survival benefits were observed only in the high Indel group. Among the subgroups defined based on both TMB and Indel rates, the high TMB and high Indel rate subgroup showed the greatest benefit from nivolumab plus chemotherapy compared with that from chemotherapy alone. The benefit of this subgroup remained significant in patients with proficient mismatch repair (MMR) tumors, whose survival outcomes were comparable to those of patients with deficient MMR tumors.Among patients treated with nivolumab plus chemotherapy, high TMB and Indel rate were independently associated with favorable survival outcomes. Conclusions Thus, Indel rate, particularly in combination with TMB, may be a promising predictive biomarker for gastric cancer. However, further validation of their predictive value is warranted.

Although venous invasion (VI) is associated with distant metastasis and observed in >50% of pT2–4 colorectal cancers (CRCs), the role of VI in pT1 CRCs is not well-defined. Methods: Thirty-four surgically resected pT1 CRCs were reevaluated for 2-dimensional (2D) VI using hematoxylin and eosin (H&E)–stained slides with additional elastic and desmin immunohistochemical staining (cohort A). Additionally, 27 pT1 CRCs without knowing VI status were selected for 3-dimensional (3D) VI evaluation only (cohort B). All 61 cases (cohorts A and B) were studied in 3D using tissue clearing. Results: VI was detected more commonly in 3D (17/34, 50.0%) than in 2D H&E slide evaluation (9/34, 26.5%, p = .047). When VI was identified in 3D (27/61, 44.3%), the most common phase was that of intraluminal growth (22/27, 81.5%), followed by intravasation (7/27, 25.9%) and extravasation (5/27, 18.5%). E-cadherin expression was characterized in 3D in foci of VI and varied in each phase of invasion. Conclusions: All three phases were observed in VI of pT1 CRCs. The extravasation of neoplastic cells from foci of VI in pT1 CRC suggests that VI could be a route of intratumoral spreading in a subset of pT1 CRCs.

Background: Circulating tumor DNA (ctDNA) is a potential biomarker in pancreatic ductal adenocarcinoma (PDAC). However, studies on residual ctDNA in patients post-chemotherapy are limited. We assessed the prognostic value of residual ctDNA in metastatic PDAC relative to that of carbohydrate antigen 19-9 (CA19-9). Methods: ctDNA analysis using a targeted next-generation sequencing panel was performed at baseline and during chemotherapy response evaluation in 53 patients. Progression-free survival (PFS) and overall survival (OS) were first evaluated based on ctDNA positivity at baseline. For further comparison, patients testing ctDNA-positive at baseline were subdivided based on residual ctDNA into ctDNA responders (no residual ctDNA post-chemotherapy) and ctDNA non-responders (residual ctDNA post-chemotherapy). Additional survival analysis was performed based on CA19-9 levels. Results: The baseline ctDNA detection rate was 56.6%. Although clinical outcomes tended to be poorer in patients with baseline ctDNA positivity than in those without, the differences were not significant. Residual ctDNA post-chemotherapy was associated with reduced PFS and OS. The prognosis of ctDNA responders was better than that of non-responders but did not significantly differ from that of ctDNA-negative individuals (no ctDNA both at baseline and during post-chemotherapy). Compared with ctDNA responses to che-motherapy, a ≥ 50% decrease in the CA19-9 level had less effect on both PFS and OSbased on hazard ratios and significance levels. ctDNA could be monitored in half of the patients whose baseline CA19-9 levels were within the reference range. Conclusions Residual ctDNA analysis post-chemotherapy is a promising approach for predicting the clinical outcomes of patients with metastatic PDAC.

Background: Observational studies have suggested associations between dietary polyunsaturated fatty acids (PUFAs) and cancer risk; however, causal inference regarding skin cancer remains limited due to potential recall bias, confounding, and reverse causation. Objective: This study aimed to evaluate the causal association between genetically predicted circulating PUFA levels and the risk of skin cancers, including basal cell carcinoma (BCC), squamous cell carcinoma (SCC), and melanoma. Methods: We conducted a 2-sample Mendelian randomization (MR) study using genome-wide association study summary statistics from the UK Biobank (PUFAs, n=115,006) and the FinnGen consortium (BCC, n=26,272; SCC, n=4,663; melanoma, n=5,753). Genetic instruments were derived for omega-3, docosahexaenoic acid, omega-6, linoleic acid, and the omega-6:3 ratio.Multiple MR methods—including inverse-variance weighted, MR-Egger, weighted median, weighted mode, and MR-PRESSO—were applied to test for consistency and assess pleiotropy and heterogeneity. Results: A higher genetically predicted linoleic acid to total fatty acid ratio was associated with a significantly lower risk of BCC and SCC. Conversely, higher genetically proxied serum omega-3 levels were associated with increased risks of BCC, SCC, and melanoma. The risk effect on SCC was attenuated upon exclusion of rs174528, a variant in the fatty acid desaturase 1 (FADS1) gene, suggesting a role for endogenous PUFA metabolism in carcinogenesis. Conclusion This MR analysis supports a causal role of circulating PUFAs in skin cancer development and highlights the importance of FADS-mediated endogenous PUFA metabolism. These findings provide novel insights into the genetic and metabolic underpinnings of skin cancer susceptibility.

Background: With the ultimate goal of developing chatbot content to address consumer inquiries about pressure injuries (PIs), this study analyzed consumer perceptions of PI using big data. Methods: This study collected text data, with PI as the central word, from three search engines (Naver, Daum, Google) from January 2019 through December 2022, using Textom version 4.5. The words were refined through text mining, keyword analysis, and TF-IDF (term frequency-inverse document frequency) analysis. N-gram analysis and centrality visualization were conducted using Ucinet 6.0. The keywords and frequencies were clustered based on the frequency of words used in CONCOR (convergence of iteration correlation) analysis. Results: Consumers for PI showed a high perception of common sites for PI, concept of PI, healthcare facility for PI, PI products, PI care, PI-related life, and PI-related disease. Conclusion Development of chatbot content customized to consumers’ needs, based on seven clusters associated with consumers’ perception of PI obtained through extensive data analysis with PI as the central word, is expected to make a significant contribution to improving consumers’ understanding of PI and enhancing the quality of PI management.