Flow cytometric quantification of intraperitoneal free tumor cells in patients with peritoneal metastasis

Flow cytometry-based analysis of tumor-leukocyte ratios in peritoneal fluid from patients with advanced gastric cancer

Background

The frequency of tumor cell dissemination in the peritoneal cavity is critically related to the progression of peritoneal metastases (PM). Recently, flow cytometry (FCM) has been successfully used to detect tumor cells in malignant effusions.

Methods

A total of 143 single cell suspensions derived from ascites or peritoneal lavages from patients with advanced gastric cancer (GC) were stained with monoclonal antibodies to CD45 and to CD326 as well as 4,6‐diamidino‐2‐phenylindole (DAPI) and FVS780. Using FCM, tumor‐leukocyte ratio (TLR) were calculated from CD45(−)CD326(+) tumor cell counts/ CD45(+)CD326(+) leukocyte counts in DAPI (+) FVS780(−) gated area. In 54 patients, the ratios of CD11b(+), CD4(+) and CD8(+) cells in CD45(+) leukocytes were evaluated in parallel.

Results

TLR of 69 patients with PM were significantly higher than those of 74 without PM (p < .001) and log(TLR) showed strong correlation with peritoneal cancer index scores in 51 PM (+) patients (r = 0.439). TLR in PM (+) patients also correlated with the ratio of CD11b (+) myeloid cells (r = 0.547), and correlated inversely with those of CD4(+) (r = −0.490) and CD8(+) T cells (r = −0.648). In PM (−) patients who underwent gastrectomy, TLR never exceeded 0.1% in patients with primary GC without serosal involvement (<T4). However, TLR in patients with T4 GC were significantly higher (p < .05) and peritoneal recurrence occurred in 6/8 patients whose TLR exceeded 0.1%.

Conclusion

TLR in peritoneal fluid reflects tumor burden and the immune environment in peritoneal cavity. Multicolor FCM may provide additional information which can be used for the treatment of the patients with PM.

Potential therapeutic strategy for gastric cancer peritoneal metastasis by NKG2D ligands-specific T cells

Purpose

Despite advancements in its treatment, gastric cancer continues to be one of the leading causes of cancer deaths worldwide. Adoptive transfer of chimeric antigen receptor-modified T cells is a promising antitumor therapy for many cancers. The purpose of this study was to construct a chimeric receptor linking the extracellular domain of NKG2D to the CD28 and CD3zeta chain intracellular domains to target gastric cancers that expressed NKG2D ligands.

Methods

Expression of NKG2D ligands including MICA, MICB, and ULBP1–3 in a gastric cancer cell line and primary gastric cancer cells from ascites samples were analyzed using flow cytometry. Co-culture experiments were performed by incubating chNKG2D T cells with gastric cancer cell lines and with primary human gastric cancer cells isolated from ascites and by measuring cytokine and chemokine release and cytotoxicity.

Results

Gastric cancer cell lines and ascites-derived primary human gastric cancer cells expressed high levels of MICA, MICB, and ULBP2. ChNKG2D T cells secreted proinflammatory cytokines and chemokines when cultured with these cancer cells. In addition, chNKG2D T cells lysed gastric cancer cell lines and the ascites-derived primary human gastric cancer cells.

Conclusion

These data indicate that treatment with chNKG2D-expressing T cells is a potential immunotherapy for gastric cancer with peritoneal metastasis.

Screening of carcinoma metastasis by flow cytometry: A study of 238 cases

BACKGROUND

Malignant epithelial cells may be detected in different specimens, by immunophenotyping using flow cytometry (FCM). CD326 (epithelial-specific antigen, clone Ber-Ep4) was used to identify epithelial cells, CD45 to discriminate between leucocytes (positive for this antigen) and non-hematological cells (negative for this antigen), and CD33 to identify monocytes/macrophages. This combination is particularly useful in effusions to characterize large cells and distinguish between monocyte/macrophages (CD45+ CD33+ CD326-), mesothelial cells (CD45 ± (dim) CD33 - CD326-) and epithelial cells (CD45 - CD33 - CD326 +). We evaluated the efficiency of flow cytometry to detect malignant epithelial cells in 238 fresh samples, including effusions, lymph node biopsies, fine needle aspirates, bone marrow aspirates, cerebrospinal fluid, among others. These are specimens expected to lack epithelial cells. FCM results were then compared to the results of smear and cell block morphology, as well as immunocytochemistry on paraffin wax embedded cell blocks, when available. Final diagnosis was the gold standard and a very good sensitivity (96.7%) and specificity (99.3%) were obtained. We concluded that the detection of CD326 positive cells using FCM is strongly indicative of the presence of carcinoma cells. © 2015 International Clinical Cytometry Society.

IFN-γ from lymphocytes induces PD-L1 expression and promotes progression of ovarian cancer

BACKGROUND

PD-L1 (programmed cell death 1 ligand 1) on tumour cells suppresses host immunity through binding to its receptor PD-1 on lymphocytes, and promotes peritoneal dissemination in mouse models of ovarian cancer. However, how PD-L1 expression is regulated in ovarian cancer microenvironment remains unclear.

METHODS

The number of CD8-positive lymphocytes and PD-L1 expression in tumour cells was assessed in ovarian cancer clinical samples. PD-L1 expression and tumour progression in mouse models under conditions of altering IFN-γ signals was assessed.

RESULTS

The number of CD8-positive cells in cancer stroma was very high in peritoneally disseminated tumours, and was strongly correlated to PD-L1 expression on the tumour cells (P<0.001). In mouse models, depleting IFNGR1 (interferon-γ receptor 1) resulted in lower level of PD-L1 expression in tumour cells, increased the number of tumour-infiltrating CD8-positive lymphocytes, inhibition of peritoneal disseminated tumour growth and longer survival (P=0.02). The injection of IFN-γ into subcutaneous tumours induced PD-L1 expression and promoted tumour growth, and PD-L1 depletion completely abrogated tumour growth caused by IFN-γ injection (P=0.01).

CONCLUSIONS

Interferon-γ secreted by CD8-positive lymphocytes upregulates PD-L1 on ovarian cancer cells and promotes tumour growth. The lymphocyte infiltration and the IFN-γ status may be the key to effective anti-PD-1 or anti-PD-L1 therapy in ovarian cancer.

IFN-γ from lymphocytes induces PD-L1 expression and promotes progression of ovarian cancer

BACKGROUND

PD-L1 (programmed cell death 1 ligand 1) on tumour cells suppresses host immunity through binding to its receptor PD-1 on lymphocytes, and promotes peritoneal dissemination in mouse models of ovarian cancer. However, how PD-L1 expression is regulated in ovarian cancer microenvironment remains unclear.

METHODS

The number of CD8-positive lymphocytes and PD-L1 expression in tumour cells was assessed in ovarian cancer clinical samples. PD-L1 expression and tumour progression in mouse models under conditions of altering IFN-γ signals was assessed.

RESULTS

The number of CD8-positive cells in cancer stroma was very high in peritoneally disseminated tumours, and was strongly correlated to PD-L1 expression on the tumour cells (P<0.001). In mouse models, depleting IFNGR1 (interferon-γ receptor 1) resulted in lower level of PD-L1 expression in tumour cells, increased the number of tumour-infiltrating CD8-positive lymphocytes, inhibition of peritoneal disseminated tumour growth and longer survival (P=0.02). The injection of IFN-γ into subcutaneous tumours induced PD-L1 expression and promoted tumour growth, and PD-L1 depletion completely abrogated tumour growth caused by IFN-γ injection (P=0.01).

CONCLUSIONS

Interferon-γ secreted by CD8-positive lymphocytes upregulates PD-L1 on ovarian cancer cells and promotes tumour growth. The lymphocyte infiltration and the IFN-γ status may be the key to effective anti-PD-1 or anti-PD-L1 therapy in ovarian cancer.

Molecular diagnosis and therapy for occult peritoneal metastasis in gastric cancer patients

To apply an individualized oncological approach to gastric cancer patients, the accurate diagnosis of disease entities is required. Peritoneal metastasis is the most frequent mode of metastasis in gastric cancer, and the tumor-node-metastasis classification includes cytological detection of intraperitoneal cancer cells as part of the staging process, denoting metastatic disease. The accuracy of cytological diagnosis leaves room for improvement; therefore, highly sensitive molecular diagnostics, such as an enzyme immunoassay, reverse transcription polymerase chain reaction, and virus-guided imaging, have been developed to detect minute cancer cells in the peritoneal cavity. Molecular targeting therapy has also been spun off from basic research in the past decade. Although conventional cytology is still the mainstay, novel approaches could serve as practical complementary diagnostics to cytology in near future.

Flow Cytometric Quantification of Intraperitoneal Free Tumor Cells is a Useful Biomarker in Gastric Cancer Patients with Peritoneal Metastasis

BACKGROUND

The frequency of intraperitoneal free tumor cells (IPTC) is considered to reflect the severity of peritoneal metastasis (PM). We quantified the relative number of IPTC against leukocytes in peritoneal fluid and evaluated its clinical relevance in gastric cancer (GC) patients, particularly those with PM.

METHODS

Cells recovered from ascites or peritoneal lavage fluid were immunostained with monoclonal antibodies (mAb) to CD45 and CD326 (EpCAM). Using flow cytometry (FACS), CD326(+) and CD45(+) cells were classified as either tumor cells (T) or leukocytes (L) and the T/L ratio (TLR) was calculated in a total of 506 samples obtained from 300 patients with GC and 33 patients with liver cirrhosis (LC).

RESULTS

Median (M) of the TLR of the initial samples obtained from 199 patients with PM(+) GC was 1.32 % (0-1,868.44 %), which was significantly higher than that in patients with PM(-) GC (M = 0 %, 0-0.35 %; n = 101) or LC (M = 0 %, 0-0.031 %; n = 33). In 104 PM(+) patients who received combination chemotherapy including intraperitoneal paclitaxel, the TLR was repeatedly measured in peritoneal fluid obtained from the port. In these patients, the TLR showed a strong correlation with clinical features as well as cytological findings and carcinoembryonic antigen messenger RNA status. Finally, the median survival time of the 11 patients with initial TLR > 10 % was significantly shorter than that of the 52 patients with TLR < 10 % (271 vs. 627 days; p = 0.0002).

CONCLUSION

The TLR excellently reflected tumor burden in the peritoneal cavity, and could be a reliable biomarker to determine the outcome, as well as the effectiveness, of chemotherapy in patients with PM(+) GC.