Intraperitoneal transfer of microRNA-29b-containing small extracellular vesicles can suppress peritoneal metastases of gastric cancer.

Small extracellular vesicles (sEV) contain various microRNAs (miRNAs) and play crucial roles in the tumor metastatic process. Although miR-29b levels in peritoneal exosomes were markedly reduced in patients with peritoneal metastases (PM), their role has not been fully clarified. In this study, we asked whether the replacement of miR-29b can affect the development of PM in a murine model. UE6E7T-12, human bone marrow-derived mesenchymal stem cells (BMSCs), were transfected with miR-29b-integrating recombinant lentiviral vector and sEV were isolated from culture supernatants using ultracentrifugation. The sEV contained markedly increased amounts of miR-29b compared with negative controls. Treatment with transforming growth factor-ß1 decreased the expression of E-cadherin and calretinin with increased expression of vimentin and fibronectin on human omental tissue-derived mesothelial cells (HPMCs). However, the effects were totally abrogated by adding miR-29b-rich sEV. The sEV inhibited proliferation and migration of HPMCs by 15% (p < 0.005, n = 6) and 70% (p < 0.005, n = 6), respectively, and inhibited adhesion of NUGC-4 and MKN45 to HPMCs by 90% (p < 0.0001, n = 5) and 77% (p < 0.0001, n = 5), respectively. MicroRNA-29b-rich murine sEV were similarly obtained using mouse BMSCs and examined for in vivo effects with a syngeneic murine model using YTN16P, a highly metastatic clone of gastric cancer cell. Intraperitoneal (IP) transfer of the sEV every 3 days markedly reduced the number of PM from YTN16P in the mesentery (p < 0.05, n = 6) and the omentum (p < 0.05, n = 6). Bone marrow mesenchymal stem cell-derived sEV are a useful carrier for IP administration of miR-29b, which can suppress the development of PM of gastric cancer.

Activated neutrophils inhibit chemotactic migration of activated T lymphocytes to CXCL11 by multiple mechanisms.

Accumulation of T lymphocytes and neutrophils shows inversed association with the prognosis of cancer patients, suggesting infiltration of neutrophils and T cells might be differently regulated in tumor tissue. In this study, we stimulated neutrophils with PMA or LPS to produce neutrophil extracellular traps (NETs) and examined the effects on chemotactic migration of activated T cells to a representative T cell chemokine, CXCL11. Migration of the activated T cells was totally abrogated by PMA-stimulated neutrophils placed either in upper or lower chamber, which was mostly canceled by pretreatment with Catalase. Although LPS-stimulated neutrophils also inhibited T cell migration, depletion of NETs by ultracentrifugation or degradation of NETs with DNAse I restored T cell migration. Western blots showed that LPS-stimulated neutrophils thoroughly degraded CXCL11 with NETs dependent manner. Activated neutrophils inhibit T cell chemotaxis via multiple mechanisms including the release of H2O2 and chemokine degradation by NETs, which may suppress adaptive immunity.

[Intraperitoneal Transfer of miR-29b Containing Exosome Suppresses the Development of Peritoneal Metastases from Gastric Cancer].

Although miR-29b levels in peritoneal exosomes was markedly reduced in patients with peritoneal metastases(PM), their role has not been fully clarified. Bone marrow derived mesenchymal stem cells(BMSC)were transfected with miR-29b- integrating lentivirus and exosomes isolated from culture supernatants using ultracentrifugation. The effects of the exosomes on human peritoneal mesothelial cells(HPMC)were examined in vitro. The in vivo effect of murine BMSC-derived exosomes was examined with a syngeneic PM model. Culture of HPMC with TGF-ß1 decreased expression of E-cadherin and calretinin with increased expression of vimentin, totally restored by adding miR-29b-rich exosomes. The exosomes inhibited proliferation and migration of HPMC, and inhibited adhesion of gastric cancer cells to HPMC. Intraperitoneal(IP)transfer of miR- 29b-rich exosomes every 3 days markedly reduced the number of PM of a murine gastric cancer cell, YTN16P, on the mesentery of C57/BL6 mice. IP administration of miR-29b-containing exosome suppresses the development of PM of gastric cancer.

Programmed cell death ligand 1 expression on monocytes is inversely correlated with tumour response to preoperative chemoradiotherapy for locally advanced rectal cancer.

AIM: The clinical efficacy of chemoradiotherapy (CRT) is largely dependent on host immune status. The aim of this study was to identify possible markers expressed on circulating mononuclear cells to predict tumour response in patients with locally advanced rectal cancer (LARC). METHODS: Peripheral blood samples were obtained from 47 patients diagnosed with LARC before and after CRT. The numbers of lymphocytes and monocyte subsets were analysed using flow cytometry. Based on clinical and pathological findings, patients were classified as high or low responders. RESULTS: Lymphocyte counts were markedly decreased after CRT. Total numbers of lymphocytes (p = 0.030) and CD4(+) T cells (p = 0.041) in post-CRT samples were significantly lower in low responders than in high responders. In contrast, monocyte counts were not reduced and the number of CD14dim (+) CD16(+) nonclassical (patrolling) monocytes were somewhat increased after CRT (p = 0.050). Moreover, the ratios of programmed cell death ligand 1 (PD-L1) (+) cells on patrolling monocytes before and after CRT were significantly higher in low responders than in high responders (p = 0.0046, p = 0.0006). The same trend was observed for classical and intermediate monocytes. The expression of PD-L1 on patrolling monocytes before CRT correlated inversely with the number of T cells and natural killer (NK) cells after CRT. PD-L1(+) ratio in patrolling monocytes was an independent predictor for response to CRT. CONCLUSION: Programmed cell death ligand 1 (PD-L1) expression on patrolling monocytes suppresses cell-mediated immunity in patients receiving CRT which could be related to tumour response, and may be a useful biomarker for decision-making in the management of patients with LARC.

Intraperitoneal Administration of Paclitaxel Combined with S-1 Plus Oxaliplatin as Induction Therapy for Patients with Advanced Gastric Cancer with Peritoneal Metastases.

BACKGROUND: Intraperitoneal (IP) administration of paclitaxel (PTX) has a great pharmacokinetic advantage to control peritoneal lesions and can be combined with various systemic chemotherapies. In this study, we evaluate the efficacy and tolerability of a combination of IP-PTX and systemic S-1/oxaliplatin (SOX) for induction chemotherapy for patients with peritoneal metastases (PM) from gastric cancer (GC). PATIENTS AND METHODS: Patients with GC who were diagnosed as macroscopic PM (P1) or positive peritoneal cytology (CY1) by staging laparoscopy between 2016 and 2019 were enrolled. PTX was IP administered at 40 mg/m2 on days 1 and 8. Oxaliplatin was IV administered at 100 mg/m2 on day 1, and S-1 was administered at 80 mg/m2/day for 14 consecutive days, repeated every 21 days. Survival time and toxicities were retrospectively explored. RESULTS: Forty-four patients received SOX + IP-PTX with a median (range) of 16 (1-48) courses, although oxaliplatin was suspended due to the hematotoxicity or intolerable peripheral neuropathy in many patients. The 1-year overall survival (OS) rate was 79.5% (95% CI 64.4-88.8%) with median survival time of 25.8 months. Gastrectomy was performed in 20 (45%) patients who showed macroscopic shrinkage of PM with a 1-year OS rate of 100% (95% CI 69.5-100%). Grade 2 and 3 histological responses was achieved in four (20%) and one (5%) patients. Grade 3/4 toxicities included neutropenia (11%), leukopenia (39%), and anemia (14%). There were no treatment-related deaths. CONCLUSIONS: Combination chemotherapy using SOX + IP-PTX regimen is highly effective and recommended as induction chemotherapy for patients with PM from GC.

Ratios of miRNAs in Peritoneal Exosomes are Useful Biomarkers to Predict Tumor Response to Intraperitoneal Chemotherapy in Patients with Peritoneal Metastases from Gastric Cancer.

BACKGROUND: Repeat intraperitoneal (IP) chemotherapy has been successfully used for treatment of peritoneal metastases (PM) from gastric cancer (GC). Exosomes play important roles not only in tumor progression but also in chemoresistance via transfer of microRNAs (miRNAs). However, there is little evidence of an effect of miRNAs in peritoneal exosomes on chemosensitivity of peritoneal lesions. METHODS: In 74 patients with advanced GC who underwent staging laparoscopy, exosomes were isolated from peritoneal fluid and expression levels of miR-21-5p, miR-223-3p, and miR-29b-3p determined using TaqMan Advanced miRNA assays. In 43 patients with PM treated with combination chemotherapy, S-1 plus Oxaliplatin together with IP Paclitaxel, the relationship between their relative expression levels and outcomes was examined. RESULTS: The ratios of miR-21-5p/miR-29b-3p and miR-223-3p/miR-29b-3p were significantly upregulated in patients with PM, especially in patients with high serum CA125 levels. They showed a mild association with Peritoneal Cancer Index (PCI) score and ascites. More impressively, the ratios were significantly higher in 16 patients with progression of PM within 1 year compared with 27 patients with an excellent tumor response (miR-21-5p/miR-29b-3p: median 17.49, range 1.83-50.90 vs. median 4.64, range 0.40-38.96, p = 0.0015, miR-223-3p/miR-29b-3p: median 1.02, range 0.23-25.85 vs. median 0.21, range 0.01-50.07, p = 0.0006). Overall survival of patients with high miR-21/miR-29b or miR-223/miR-29b ratios was significantly worse than in patients with low ratios (p = 0.0117, p = 0.0021). CONCLUSIONS: The ratios of miRNAs in peritoneal exosome correlate with survival of the patients with PM from GC and suggest the possibility that they modify the chemosensitivity against IP chemotherapy.

Surgical Stress Increases Circulating Low-Density Neutrophils Which May Promote Tumor Recurrence.

BACKGROUND: Low-density neutrophils (LDN) have been shown to be increased in peripheral blood in patients with various diseases and closely related to immune-mediated pathology. However, the frequency and function of LDN in circulating blood of the patients following abdominal surgery have not been well understood. METHODS: LDN were determined by CD66b(+) cells, which were copurified with mononuclear cells by density gradient preparations of peripheral blood of surgical patients. The effects of the purified LDN on T cell proliferation and tumor cell lysis were examined in vitro. Neutrophil extracellular traps (NETs) production was examined by extracellular nuclear staining. RESULTS: The number of LDN with an immature phenotype is markedly increased in peripheral blood samples in patients after abdominal surgery. The frequency of LDN correlated positively with operative time and intraoperative blood loss. The purified LDN significantly suppressed the proliferation of autologous T cells stimulated with anti-CD3 mAb coated on plate and partially inhibited the cytotoxicity of lymphocytes activated with recombinant interleukin-2 against a human gastric cancer cell, OCUM-1. The LDN also produced NETs after short-term culture in vitro, which efficiently trap many OCUM-1. These results suggest that surgical stress recruits immunosuppressive LDN in the circulation in the early postoperative period. CONCLUSIONS: The LDN may support the lodging of circulating tumor cells via NETs formation and inhibit T cell-mediated antitumor response in target organs, which may promote postoperative cancer metastases. Functional blockade of LDN might be an effective strategy to reduce tumor recurrence after abdominal surgery.

[Mediastinal Thyroid Carcinoma;Report of a Case].

71-year-old woman was pointed out to have an asymptomatic mediastinal tumor. Chest computed tomography(CT) showed a well-demarcated mass measuring 7 cm in diameter in the anterior mediastinum. We resected the mass through a median sternotomy. The tumor had a clear margin without invasion to the surrounding tissue and did not show continuity with the cervical thyroid gland. Histopathologically, the tumor was diagnosed as follicular thyroid carcinoma with capsular invasion. This is an exceptionally rare case.

[Purtscher's retinopathy following blunt chest compression].

Following chest or abdominal injury, acute blurring of vision occurs without direct eye injury. This disease is known as Purtscher's retinopathy. A 74-year-old man suffered blunt chest injury by air bag inflation at traffic accident. Next morning, he suddenly complained of visual abnormality. An ophthalmoscopy revealed multiple cotton-wool exudation and retinal edema. He was diagnosed as Purtscher's retinopathy. The symptoms of soft exudation and retinal edema gradually resolved. The visual acuity gradually improved, but not reached to the previous level. We must be aware of this retinopathy, since this is rare but sometimes sight-threatening condition.

Vagus nerve signal has an inhibitory influence on the development of peritoneal metastasis in murine gastric cancer.

The vagus nerve is the only pathway for transmitting parasympathetic signals between the brain and thoracoabdominal organs, thereby exhibiting anti-inflammatory functions through the cholinergic anti-inflammatory pathway. Despite often being resected during lymph node dissection in upper gastrointestinal cancer surgery, the impact of vagotomy on postoperative outcomes in gastric cancer patients remains unclear. Sub-diaphragmatic vagotomy was performed on C57BL/6 mice. Three weeks later, syngeneic murine gastric cancer cell line YTN16P was injected into the peritoneal cavity, and the number of peritoneal metastases (PM) on the mesentery and omentum compared with control mice. The phenotypes of immune cells in peritoneal lavage and omental milky spots one day after tumor inoculation were analyzed using flow cytometry and immunohistochemistry. Intraperitoneal transfer of 3 × 105 YTN16P significantly increased the number of metastatic nodules on the mesentery in the vagotomy group compared to the control group. The omental metastasis grade was also significantly higher in the vagotomy group. Phenotypic analysis of immune cells in peritoneal lavage did not reveal significant differences after vagotomy. However, vagotomized mice exhibited a notable increase in milky spot area, with a higher presence of cytokeratin(+) tumor cells, F4/80(+) macrophages, and CD3(+) T cells. Vagus nerve signaling appears to regulate the immune response dynamics within milky spots against disseminated tumor cells and inhibits the development of PM. Preserving the vagus nerve may offer advantages in advanced gastric cancer surgery to reduce peritoneal recurrence.

Splenectomy has opposite effects on the growth of primary compared with metastatic tumors in a murine colon cancer model.

The spleen is a key source of circulating and tumor-infiltrating immune cells. However, the effect of splenectomy on tumor growth remains unclear. At 3 weeks after splenectomy, we subcutaneously injected LuM1 cells into BALB/c mice and evaluated the growth of primary tumors and lung metastases at 4 weeks after tumor inoculation. In addition, we examined the phenotypes of immune cells in peripheral blood by using flow cytometry and in tumor tissue by using multiplex immunohistochemistry. The growth of primary tumors was reduced in splenectomized mice compared with the sham-operated group. Conversely, splenectomized mice had more lung metastases. Splenectomized mice had fewer CD11b+cells, especially monocytic MDSCs (CD11b+Gr-1neg-lowLy6chigh), and NK cells (CD49b+CD335+). The proportion of NK cells was inversely correlated with the number of lung metastases. In splenectomized mice, the density of CD3+ and granzyme B+ CD8+ T cells was increased, with fewer M2-type macrophages in primary tumors, but NK cells were decreased markedly in lung. Splenectomy concurrently enhances T cell-mediated acquired immunity by reducing the number of monocytic MDSCs and suppresses innate immunity by decreasing the number of NK cells. Splenectomy has opposite effects on primary and metastatic lesions through differential regulation on these two immune systems.

Peripheral low-density granulocytes after colorectal cancer surgery in predicting recurrence.

BACKGROUND: Low-density granulocytes (LDGs) have been shown to be increased in the peripheral blood of patients with inflammatory and malignant diseases. This study evaluated LDGs in patients who underwent radical surgery for colorectal cancer (CRC) and their impact on survival. METHODS: Patients who underwent radical colectomy between 2017 to 2021 were screened for enrolment in the study. Peripheral blood was obtained in the operating room before and after surgery and cells were recovered from the mononuclear layer after density gradient preparations. The ratio of CD66b(+) LDG to CD45(+) leukocytes was determined with flow cytometry, and the association of the ratios with patient outcomes was examined. The main outcome of interest was recurrence-free survival (RFS). RESULTS: Out of 228 patients treated, 176 were enrolled, including 108 colonic and 68 rectal cancers. Overall, 38 patients were stage I, 30 were stage II, 72 were stage 3, and 36 were stage IV. The number of LDGs was markedly increased immediately after surgery and the proportion of LDGs correlated positively with operating time (r = 0.2806, P < 0.001) and intraoperative blood loss (r = 0.1838, P = 0.014). Purified LDGs produced high amounts of neutrophil extracellular traps after short-term culture and efficiently trapped tumour cells in vitro. The proportion of postoperative LDGs was significantly higher in 13 patients who developed recurrence (median 9 (range 1.63-47.0)) per cent versus median 2.93 ((range 0.035-59.45) per cent, P = 0.013). When cut-off values were set at 4.9 per cent, a higher proportion of LDGs was strongly and independently associated with decreased RFS (P = 0.005). In patients with stage III disease, adjuvant chemotherapy significantly improved RFS of patients with high ratios of LDGs, but not low LDGs. CONCLUSION: LDGs are recruited to circulating blood by surgical stress early in the postoperative interval after colectomy for colonic cancer and their postoperative proportion is correlated with recurrence.

Combined Intraperitoneal Paclitaxel and Systemic Chemotherapy for Patients with Massive Malignant Ascites Secondary to Pancreatic Cancer: A Report of Two Patients.

The prognosis of patients with peritoneal metastases from pancreatic cancer is poor, largely due to massive ascites, which precludes systemic treatment. Two patients with a poor performance status and malignant ascites were treated with cell-free and concentrated ascites reinfusion therapy followed by combined chemotherapy with intraperitoneal paclitaxel, intravenous gemcitabine, and nab-paclitaxel. These patients achieved a survival of 19 and 36 weeks with a relatively good quality of life. Combined intraperitoneal paclitaxel and systemic chemotherapy may provide effective palliative management for some patients with peritoneal metastases from pancreatic cancer.

Semaphorin 3C is involved in the progression of gastric cancer.

Malignant tumors are often associated with denervation, suggesting the functional implication of axonal guidance molecules in tumor growth. Here, we assessed the role of semaphorin 3C (sema3C) in the progression of gastric cancer. Immunohistochemistry of human samples revealed that sema3C was strongly expressed in neoplastic cells, especially at the invasion front. Stable transfection of target sequences of sema3C miRNA did not affect the in vitro proliferative activity of human gastric cancer AZ-521 cells. However, when the tumor growth was examined in vivo using an orthotopic model in nude mice, primary stomach tumors as well as metastatic liver tumors were significantly suppressed by sema3C silencing with the reduction of microvessel density. Immunostaining of primary tumor indicated the rate of Ki-67 positive carcinoma cells was decreased, whereas that of apoptotic cells was significantly increased in sema3C-silenced tumor. In addition, capillary-like tubular formation was reduced by the addition of culture media of sema3C miRNA cells compared with the media of control miRNA cells. Semaphorin 3C is positively expressed in gastric cancer cells and may be involved in tumor progression, presumably through the stimulation of angiogenesis.

Vagus nerve preservation selectively restores visceral fat volume in patients with early gastric cancer who underwent gastrectomy.

BACKGROUND: Body weight loss is a well-known complication after gastrectomy, and is mainly due to reduced fat volume. The effect of vagotomy on the postoperative fat volume was investigated in patients with early stage gastric cancer who underwent gastrectomy. METHODS: Subcutaneous fat area (SFA) and visceral fat area (VFA) were separately measured in a computed tomographic (CT) image at the level of the umbilicus using Fat Scan software. The changes in these two fat areas were determined by comparing CT images taken before and more than 6 mo after gastrectomy, and the ratio of postoperative to preoperative fat area was calculated in 77 patients. RESULTS: VFA was reduced significantly greater after total gastrectomy (TG) than distal gastrectomy (DG) (P = 0.0003). In 63 patients who underwent DG, the reduction in VFA, but not in SFA, was significantly less in vagus nerve-preserved than in vagus nerve-nonpreserved cases (59.0% ± 24.2% versus 74.9% ± 28.2%, P = 0.027). If compared in each case, VFA showed a significantly greater decrease than did SFA in vagus-nonpreserving, but not in vagus-preserving, gastrectomy (68.2% ± 37.0% versus 52.7% ± 25.2%, P < 0.0001; 76.3% ± 30.0% versus 74.9% ± 28.2%, P = 0.79). CONCLUSIONS: The vagus nerve has a function to locally regulate the amount of intra-abdominal fat tissue, and selective vagotomy in gastrectomy results in a preferential reduction of visceral fat in gastrectomy. Surgical denervation of vagus may be reconsidered as a reasonable treatment for excessive obesity.

Vagus nerve preservation results in visceral fat maintenance after distal gastrectomy.

BACKGROUND/AIMS: Although preservation of the vaguas nerve is recommended in surgery for earlystage gastric cancer, the physiological effect of vagotomy on the postoperative course has not been well documented. We assessed the effect of vagotomy on the change in fat volume after gastrectomy. METHODOLOGY: Subcutaneous fat area (SFA) and visceral fat area (VFA) were separately measured in computed tomographic images taken before and more than 6 months after surgery, using Fat Scan software. The ratios of postoperative/ preoperative values of these two fat areas as well as body weight were calculated in 45 patients who underwent DG with (n=24) or without (n=21) vagotomy. RESULTS: Vagotomy did not affect the change in body weight (91.3±1.7% vs. 92.1±1.7%). In patients with vagotomy, VFA was reduced to 59.0±5.1%, which was significantly greater than the reduction in SFA (74.3±8.7%, p=0.042). In contrast, the reduction ratios of VFA and SFA were equal in vagus nerve-preserved patients (78.4±6.7% vs. 78.2±6.9%, p=0.97). CONCLUSIONS: The vagus nerve may have a function to locally regulate the intra-abdominal fat volume and preservation of the vagus nerve results in the maintenance of visceral fat after DG.

Primary hepatic methotrexate-associated lymphoproliferative disorder associated with Epstein-Barr virus reactivation and accompanied by spontaneous necrosis: A case report.

RATIONALE: Methotrexate-associated lymphoproliferative disorder (MTX-LPD) is a major complication of methotrexate (MTX) therapy that can develop in patients with rheumatoid arthritis (RA), although primary hepatic MTX-LPD is extremely rare. Discontinuation of MTX results in remission in half of the patients with MTX-LPDs and is one treatment approach. PATIENT CONCERN: A 64-year-old Japanese woman suffering from rheumatoid arthritis treated with MTX presented with upper abdominal pain. DIAGNOSIS: Pathological evaluation showed that the tumor contained geographic necrosis and proliferation of large atypical lymphocytes strongly positive for cluster of differentiation 20 (CD20) antigen with immunohistochemical staining and Epstein-Barr Virus-encoded RNA transcript by in situ hybridization. The tumor was finally diagnosed as a primary hepatic MTX-associated Epstein-Barr Virus positive B-cell LPD. INTERVENTIONS: Left hepatic lobectomy was performed for diagnosis and therapy. OUTCOMES: No sighs of recurrence were observed for 2 years. LESSONS: This patient demonstrated that MTX-LPD could arise in the liver, although it is rare. If liver tumors arise in patients taking MTX, examination of sIL-2R, Epstein-Barr virus-VCA IgG and EBNA might support the diagnosis of MTX-LPD. In this case, the primary hepatic MTX-LPD became necrotic without discontinuation of MTX. It is generally believed that withdrawal of MTX restores antitumor immunity resulting in tumor necrosis. This case indicates that spontaneous regression might occur without any treatment in some patients treated for RA with MTX-LPD. The relationship between MTX-LPD and spontaneous necrosis is unclear and further data is required to characterize the types of patients that will develop spontaneous regression without intervention.

Effect of Systemic or Intraperitoneal Administration of Anti-PD-1 Antibody for Peritoneal Metastases from Gastric Cancer.

BACKGROUND/AIM: Programmed death-1 (PD-1)/PD-ligand 1 (PD-L1) blockade therapy is widely used for the treatment of patients with metastatic gastric cancer (GC). However, it is unclear how PD-1 antibodies affect the local immunity related to the growth of peritoneal metastases (PM). The clinical efficacy of PD-1/PD-L1 inhibitors against PM from GC has not been clearly determined. MATERIALS AND METHODS: We established a highly metastatic subclone of murine GC cells to the peritoneum, YTN16P, by in vivo selection and evaluated the effects of intravenous (IV) or intraperitoneal (IP) administration of anti-PD-1 antibody on PM in immunocompetent mice model. Phenotypes of immune cells in the spleen and peritoneal metastatic lesions were determined with flow cytometry and immunohistochemistry. RESULTS: IP inoculation of YTN16P (1×106) resulted in multiple mesenteric metastases after 3 weeks. IV and IP administration of anti-PD-1mAb reduced the number of metastases to the mesentery by 30~40% compared with isotype controls. However, no differences were observed depending on the route of administration. Although splenocyte phenotypes were not altered, the densities of CD8(+) T cells in peritoneal tumors were significantly increased, whereas those of Gr-1(+) myeloid derived suppressor cells (MDSC) were significantly reduced in mice treated with anti-PD-1 mAb. CONCLUSION: PD-1 blockade therapy remodels the cellular immune composition of peritoneal tumors, which can partially suppress the PM from GC regardless of the route of administration. Adding anti-PD-1 antibody to chemotherapeutic regimens may enhance their anti-tumor effects against PM, which can lead to the prolongation of survival of patients with GC with peritoneal involvement.

Novel Drug Delivery Method Targeting Para-Aortic Lymph Nodes by Retrograde Infusion of Paclitaxel into Pigs' Thoracic Duct.

Gastrointestinal cancer with massive nodal metastases is a lethal disease. In this study, using a porcine model, we infused the anti-cancer drug Paclitaxel (PTX) into thoracic ducts to examine the efficiency of drug delivery to intra-abdominal lymph nodes. We established a technical method to catheterize the thoracic duct in the necks of pigs. We then compared the pharmacokinetics of PTX administered intrathoracically with those of systemic (intravenous) infusion. Serum, liver, and spleen concentrations of PTX were significantly lower following thoracic duct (IT) infusion than after intravenous (IV) administration approximately 1-8 h post-infusion. However, PTX levels in abdominal lymph nodes were maintained at relatively high levels up to 24 h after IT infusion compared to after IV infusion. Concentrations of PTX in urine were much higher after IT administration than after IV administration. After IT infusion, the same concentration of PTX was obtained in abdominal lymph nodes, but the serum concentration was lower than after systemic infusion. Therefore, IT infusion may be able to achieve higher PTX doses than IV infusion. IT delivery of anti-cancer drugs into the thoracic duct may yield clinical benefits for patients with extensive lymphatic metastases in abdominal malignancies.

Altered intraperitoneal immune microenvironment in patients with peritoneal metastases from gastric cancer.

Background: The peritoneal cavity contains many site-specific immune cells which constitute a unique immune microenvironment. However, it is unclear how the local immune signature is altered in patients with peritoneal metastases (PM). Methods: Peritoneal lavage fluid or ascites were obtained from 122 patients with various stages of gastric cancer (GC). Cells recovered from peritoneal fluids were immunostained with mAbs for lymphocyte-, macrophage- and tumor cell-specific antigens and the frequencies of leukocyte subsets and antigen expression levels were evaluated with multi-color flowcytometry. Results: The proportions of CD8(+) T cells, CD3(+)CD56(+) NKT-like cells, and CD3(-)CD56(+) NK cells to CD45(+) leukocytes were significantly reduced in patients with PM compared to those without PM. In patients with PM, the rates of CD8 (+) T cells and NKT-like cells correlated inversely with the tumor leukocyte ratio (TLR), the relative frequency of CD326(+) tumor cells to CD45(+) leukocytes. In contrast, the proportion of CD19(+) B cells was significantly increased in patients with PM, and their proportion correlated positively with the TLR and peritoneal carcinomatosis index (PCI) score. In patients with PM, CD14(+) macrophages tended to be increased with enhanced expression of CD14, CD16 and a M2-macrophage marker, CD163. In particular, macrophages in patients with high TLR contained many granules with high side scatter and CD14 expression in their flow profile compared to those without PM. Conclusion: PM are accompanied by a drastic change in phenotypes of lymphocyte and macrophage in the peritoneal cavity, which might be involved in the development and progression of intraperitoneal tumor growth.