大澤 英之

BACKGROUND: Patients with advanced gastric cancer (GC) with peritoneal involvement have a dismal prognosis. Recent clinical trials have shown that anti-Claudin18.2 (CLDN18.2) antibody (zolbetuximab) enhances survival in patients with GC expressing high levels of CLDN18.2. However, the effectiveness of the zolbetuximab in patients with peritoneal metastases (PMs) remains unclear. In this study, we aimed to evaluate the expression of CLDN18.2 in disseminated lesions to assess the clinical utility of zolbetuximab in the treatment of GC with PM. METHODS: In 42 patients diagnosed with stage IV GC with PM, biopsy samples from the primary tumors and peritoneal metastatic nodules were collected and immunostained using the specific antibody (43-14A, Ventana). The expression of CLDN18.2 was comparatively evaluated based on staining intensity and the proportion of positive cells. RESULTS: Positive immunoreactivity of CLDN18.2 was observed in 37 (88%) of the primary tumors. Specifically, CLDN18.2 positivity was identified in 26 (62%) or 12 (29%) patients based on moderate to strong membrane staining in at least 40% or 75% of tumor cells, respectively. In comparison, the staining intensity in tumor cells was consistently reduced in PM across all patients. CLDN18.2 expression was absent in PM of 29 (69%) patients, while 3 (7.1%) cases were determined to be CLDN18.2-positive based on a cutoff value of 40% for high staining. This trend was particularly pronounced in cases with undifferentiated type and human epidermal growth factor receptor 2 (HER-2) negative primary tumors. CONCLUSIONS: Although CLDN18.2 expression in PM mirrored that in primary lesions, the levels were generally reduced. When zolbetuximab is used for GC patients with peritoneal involvement, it is preferable to assess the expression of CLDN18.2 in the disseminated lesions.

BACKGROUND: Globally, prevalence of metabolic dysfunction-associated steatotic liver disease (MASLD) is increasing, and there is an urgent need to develop innovative therapies that promote liver regeneration following hepatectomy for this disease. Surgical excision is a key therapeutic approach with curative potential for liver tumors. However, hepatic steatosis can lead to delayed liver regeneration and higher post-operative complication risk. Mesenchymal stem cells-conditioned medium (MSC-CM) is considered a rich source of paracrine factors that can repair tissues and restore function of damaged organs. Meanwhile, hydrogels have been widely recognized to load MSC secretome and achieve sustained release. This study aimed to evaluate the therapeutic effect of hydrogel-encapsulated MSC-CM on liver regeneration following partial hepatectomy (PHx) in a rodent model of diet-induced hepatic steatosis. METHODS: Male Lewis rats were fed with a methionine and choline-deficient diet. After 3 weeks of feeding, PHx was performed and rats were randomly allocated into two groups that received hydrogel-encapsulated MSC-CM or vehicle via the intra-mesenteric space of the superior mesenteric vein (SMV). RESULTS: The regeneration of the remnant liver at 30 and 168 h after PHx was significantly accelerated, and the expressions of proliferating cell nuclear antigen were significantly enhanced in the MSC-CM group. MSC-CM treatment significantly increased hepatic ATP and β-hydroxybutyrate content at 168 h after PHx, indicating that MSC-CM fosters regeneration not only in volume but also in functionality. The number of each TUNEL- and cleaved caspase-3 positive nuclei in hepatocytes at 9 h after PHx were significantly decreased in the MSC-CM group, suggesting that MSC-CM suppressed apoptosis. MSC-CM increased serum immunoregulatory cytokine interleukin-10 and interleukin-13 at 30 h after PHx. Additionally, mitotic figures and cyclin D1 expression decreased and hepatocyte size increased in the MSC-CM group, implying that this mode of regeneration was mainly through cell hypertrophy rather than cell division. CONCLUSIONS: MSC-CM represents a novel therapeutic approach for patients with MASLD requiring PHx.

This study explores a novel therapeutic approach for peritoneal metastasis (PM) using AAV-mediated delivery of tumor suppressor microRNA-29b (miR-29b) to peritoneal mesothelial cells (PMC). AAV serotypes 2 and DJ demonstrate high transduction efficiency for human and murine PMC, respectively. In vitro analysis indicates that AAV vectors encoding miR-29b precursor successfully elevate miR-29b expression in PMC and their secreted small extracellular vesicle (sEV), thereby inhibiting mesothelial mesenchymal transition and reducing subsequent attachment of tumor cells. A single intraperitoneal (IP) administration of AAV-DJ-miR-29b demonstrates robust and sustained transgene expression, suppressing peritoneal fibrosis and inhibiting the development of PM from gastric and pancreatic cancers. Additionally, AAV-DJ-miR-29b enhances the efficacy of IP chemotherapy using paclitaxel, restraining the growth of established PM. While conventional gene therapy for cancer encounters challenges targeting tumor cells directly but delivering miRNA to the tumor stroma offers a straightforward and efficient means of altering the microenvironment, leading to substantial inhibition of tumor growth. AAV-mediated miR-29b delivery to peritoneum via IP route presents a simple, minimally invasive, and promising therapeutic strategy for refractory PM.