STAT3 Contributes a Favorable Response to Pembrolizumab Through IFN-γ-induced Apoptosis in Urothelial Cancer.

BACKGROUND/AIM: Pembrolizumab, a second-line therapy for platinum-refractory advanced urothelial carcinoma (UC), is needed to improve objective response rate. Hence, it is crucial to identify optimal predictive biomarkers of responses. This study aimed to clarify the predictive value and role of signal transducer and activator of transcription 3 (STAT3) in selecting patients with advanced UC who might benefit clinically from pembrolizumab therapy. PATIENTS AND METHODS: We retrospectively analyzed 31 patients who received pembrolizumab therapy for UC. STAT3, phosphorylated STAT3 (p-STAT3), and PD-L1 expression were determined using tissue microarrays constructed from patient-derived specimens, and the association of these expression levels with overall survival was analyzed. We assessed the functional role of STAT3 in bladder cancer cell lines in response to interferon-gamma (IFN-γ). RESULTS: Patients with high STAT3 or p-STAT3 expression, and high platelet-to-lymphocyte ratio (PLR) (n=6) had a significantly shorter OS; in the other patients (n=25), high STAT3 or p-STAT3 expression was significantly associated with improved prognosis. IFN-γ-induced apoptosis was partially dependent on STAT3 in T24 cells but not in JMSU1 cells. CONCLUSION: In patients with advanced UC, STAT3 plays a key role in mediating the efficacy of pembrolizumab through apoptosis in response to IFN-γ.

Positive regulatory loop of platelet-derived growth factor DD-induced STAT3 activation is associated with poor prognosis in advanced urothelial carcinoma.

Immune checkpoint inhibitor (ICI) therapy has been established for patients with advanced urothelial cancer (UC). The necessity of overcoming resistance to ICIs and identifying a predictive factor for the same has been highlighted, such as the assessment of combination therapy with other targeted drugs and the characterization of molecular signatures in the tumor microenvironment. Recently, we reported that low hemoglobin (Hb) levels and a high platelet-to-lymphocyte ratio (PLR) were significantly associated with overall survival in patients with UC who did not benefit from pembrolizumab treatment. In the present study, we identified a possible link between these unfavorable prognostic indicators and PDGF-DD-induced STAT3 activation in UC. Overlapping patients between the high STAT3- or phosphorylated STAT3-positive score group (as assessed by immunohistochemistry) and low Hb levels or high PLR group (as assessed by blood tests) showed significantly worse outcomes after pembrolizumab treatment. Additionally, using the bladder cancer JMSU1 cell line, we demonstrated a possible positive regulatory loop between autocrine/paracrine PDGF-DD and STAT3 signaling. Therefore, we suggest that STAT3 inhibition and PDGF-DD detection in the tumor microenvironment might represent a potential therapeutic strategy to overcome resistance to pembrolizumab. Moreover, this can help identify patients with UC who could benefit from combination treatment.

DNA Ligase 4 Contributes to Cell Proliferation against DNA-PK Inhibition in MYCN-Amplified Neuroblastoma IMR32 Cells.

Identifying the vulnerability of altered DNA repair machinery that displays synthetic lethality with MYCN amplification is a therapeutic rationale in unfavourable neuroblastoma. However, none of the inhibitors for DNA repair proteins are established as standard therapy in neuroblastoma. Here, we investigated whether DNA-PK inhibitor (DNA-PKi) could inhibit the proliferation of spheroids derived from neuroblastomas of MYCN transgenic mice and MYCN-amplified neuroblastoma cell lines. DNA-PKi exhibited an inhibitory effect on the proliferation of MYCN-driven neuroblastoma spheroids, whereas variable sensitivity was observed in those cell lines. Among them, the accelerated proliferation of IMR32 cells was dependent on DNA ligase 4 (LIG4), which comprises the canonical non-homologous end-joining pathway of DNA repair. Notably, LIG4 was identified as one of the worst prognostic factors in patients with MYCN-amplified neuroblastomas. It may play complementary roles in DNA-PK deficiency, suggesting the therapeutic potential of LIG4 inhibition in combination with DNA-PKi for MYCN-amplified neuroblastomas to overcome resistance to multimodal therapy.

ATM depletion induces proteasomal degradation of FANCD2 and sensitizes neuroblastoma cells to PARP inhibitors.

BACKGROUND: Genomic alterations, including loss of function in chromosome band 11q22-23, are frequently observed in neuroblastoma, which is the most common extracranial childhood tumour. In neuroblastoma, ATM, a DNA damage response-associated gene located on 11q22-23, has been linked to tumorigenicity. Genetic changes in ATM are heterozygous in most tumours. However, it is unclear how ATM is associated with tumorigenesis and cancer aggressiveness. METHODS: To elucidate its molecular mechanism of action, we established ATM-inactivated NGP and CHP-134 neuroblastoma cell lines using CRISPR/Cas9 genome editing. The knock out cells were rigorously characterized by analyzing proliferation, colony forming abilities and responses to PARP inhibitor (Olaparib). Western blot analyses were performed to detect different protein expression related to DNA repair pathway. ShRNA lentiviral vectors were used to knockdown ATM expression in SK-N-AS and SK-N-SH neuroblastoma cell lines. ATM knock out cells were stably transfected with FANCD2 expression plasmid to over-expressed the FANCD2. Moreover, knock out cells were treated with proteasome inhibitor MG132 to determine the protein stability of FANCD2. FANCD2, RAD51 and γH2AX protein expressions were determined by Immunofluorescence microscopy. RESULTS: Haploinsufficient ATM resulted in increased proliferation (p < 0.01) and cell survival following PARP inhibitor (olaparib) treatment. However, complete ATM knockout decreased proliferation (p < 0.01) and promoted cell susceptibility to olaparib (p < 0.01). Complete loss of ATM suppressed the expression of DNA repair-associated molecules FANCD2 and RAD51 and induced DNA damage in neuroblastoma cells. A marked downregulation of FANCD2 expression was also observed in shRNA-mediated ATM-knockdown neuroblastoma cells. Inhibitor experiments demonstrated that the degradation of FANCD2 was regulated at the protein level through the ubiquitin-proteasome pathway. Reintroduction of FANCD2 expression is sufficient to reverse decreased proliferation mediated by ATM depletion. CONCLUSIONS: Our study revealed the molecular mechanism underlying ATM heterozygosity in neuroblastomas and elucidated that ATM inactivation enhances the susceptibility of neuroblastoma cells to olaparib treatment. These findings might be useful in the treatment of high-risk NB patients showing ATM zygosity and aggressive cancer progression in future.

Pretreatment Hemoglobin Levels and Platelet-to-Lymphocyte Ratio Predict Survival Benefit from Pembrolizumab in Advanced Urothelial Carcinoma.

BACKGROUND/AIM: Several prognostic risk factors have been recognized when using cisplatin-based conventional chemotherapy for the treatment of advanced urothelial carcinoma (UC); these include performance status (PS), liver metastasis, hemoglobin (Hb) levels, time from prior chemotherapy (TFPC), and other systemic inflammation scores including neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR). However, the benefit of these indicators for predicting outcome of immune checkpoint inhibitors is not fully understood. Here, we investigated the predictive value of the indicators in patients who received pembrolizumab for the treatment of advanced UC. PATIENTS AND METHODS: Seventy-five patients who received pembrolizumab treatment for advanced UC were included. The Karnofsky PS, liver metastasis, hemoglobin levels, TFPC, NLR, and PLR were analyzed, and their relationship with overall survival (OS) was determined. RESULTS: All factors were highlighted as significant prognostic indicators for OS in the univariate proportional regression analysis (p<0.05 for each). Multivariate analysis revealed that Karnofsky PS and liver metastasis were independent prognostic indicators for OS (p<0.01) but were applicable only for a small number of patients. Notably, the combined analysis with low Hb levels and high PLR was significantly associated with OS in patients who could gain less benefit from pembrolizumab at a median of 6.6 [95% confidence interval (CI)=4.2-9.0] versus 15.1 (95% CI=12.4-17.8) months (p=0.002). CONCLUSION: The combination of Hb levels and PLR may be a broadly applicable indicator for the outcome of pembrolizumab as second-line chemotherapy in patients with advanced UC.

The RUNX Family Defines Trk Phenotype and Aggressiveness of Human Neuroblastoma through Regulation of p53 and MYCN.

The Runt-related transcription factor (RUNX) family, which is essential for the differentiation of cells of neural crest origin, also plays a potential role in neuroblastoma tumorigenesis. Consecutive studies in various tumor types have demonstrated that the RUNX family can play either pro-tumorigenic or anti-tumorigenic roles in a context-dependent manner, including in response to chemotherapeutic agents. However, in primary neuroblastomas, RUNX3 acts as a tumor-suppressor, whereas RUNX1 bifunctionally regulates cell proliferation according to the characterized genetic and epigenetic backgrounds, including MYCN oncogenesis. In this review, we first highlight the current knowledge regarding the mechanism through which the RUNX family regulates the neurotrophin receptors known as the tropomyosin-related kinase (Trk) family, which are significantly associated with neuroblastoma aggressiveness. We then focus on the possible involvement of the RUNX family in functional alterations of the p53 family members that execute either tumor-suppressive or dominant-negative functions in neuroblastoma tumorigenesis. By examining the tripartite relationship between the RUNX, Trk, and p53 families, in addition to the oncogene MYCN, we endeavor to elucidate the possible contribution of the RUNX family to neuroblastoma tumorigenesis for a better understanding of potential future molecular-based therapies.

Polycomb EZH1 regulates cell cycle/5-fluorouracil sensitivity of neuroblastoma cells in concert with MYCN.

In the present study, we found that EZH1 depletion in MYCN-amplified neuroblastoma cells resulted in significant cell death as well as xenograft inhibition. EZH1 depletion decreased the level of H3K27me1; the interaction and protein stabilization of MYCN and EZH1 appear to play roles in epigenetic transcriptional regulation. Transcriptome analysis of EZH1-depleted cells resulted in downregulation of the cell cycle progression-related pathway. In particular, Gene Set Enrichment Analysis revealed downregulation of reactome E2F-mediated regulation of DNA replication along with key genes of this process, TYMS, POLA2, and CCNA1. TYMS and POLA2 were transcriptionally activated by MYCN and EZH1-related epigenetic modification. Treatment with the EZH1/2 inhibitor UNC1999 also induced cell death, decreased H3K27 methylation, and reduced the levels of TYMS in neuroblastoma cells. Previous reports indicated neuroblastoma cells are resistant to 5-fluorouracil (5-FU) and TYMS (encoding thymidylate synthetase) has been considered the primary site of action for folate analogues. Intriguingly, UNC1999 treatment significantly sensitized MYCN-amplified neuroblastoma cells to 5-FU treatment, suggesting that EZH inhibition could be an effective strategy for development of a new epigenetic treatment for neuroblastoma.

Platelet-to-Lymphocyte Ratio Predicts the Efficacy of Pembrolizumab in Patients With Urothelial Carcinoma.

BACKGROUND/AIM: This study aimed to determine useful predictive factors for selecting patients with advanced urothelial carcinoma (UC) who might benefit clinically from treatment with pembrolizumab. PATIENTS AND METHODS: We retrospectively analyzed 54 patients who underwent pembrolizumab treatment for UC. The hemoglobin, albumin, lymphocyte and platelet (HALP) score, neutrophil-to-lymphocyte ratio (NLR), and platelet-to-lymphocyte ratio (PLR) were calculated as indices of systemic inflammatory response, and the relationships between these scores and the initial tumor response or overall survival, as well as other clinicopathological factors, were assessed. RESULTS: High NLR and PLR were associated with a poor initial tumor response to pembrolizumab. A HALP score <30.05 and a PLR ≥173.73 were associated with worse overall survival. In the multivariate Cox regression analysis, a high PLR was a significant independent prognostic factor for unfavorable outcomes. CONCLUSION: A high pretreatment PLR may be a valuable indicator for choosing therapy other than pembrolizumab in patients with advanced UC.

FGFR2 loss sensitizes MYCN-amplified neuroblastoma CHP134 cells to CHK1 inhibitor-induced apoptosis.

Checkpoint kinase 1 (CHK1) plays a key role in genome surveillance and integrity throughout the cell cycle. Selective inhibitors of CHK1 (CHK1i) are undergoing clinical evaluation for various human malignancies, including neuroblastoma. In this study, one CHK1i-sensitive neuroblastoma cell line, CHP134, was investigated, which characteristically carries MYCN amplification and a chromosome deletion within the 10q region. Among several cancer-related genes in the chromosome 10q region, mRNA expression of fibroblast growth factor receptor 2 (FGFR2) was altered in CHP134 cells and associated with an unfavorable prognosis of patients with neuroblastoma. Induced expression of FGFR2 in CHP134 cells reactivated downstream MEK/ERK signaling and resulted in cells resistant to CHK1i-mediated cell growth inhibition. Consistently, the MEK1/2 inhibitor, trametinib, potentiated CHK1 inhibitor-mediated cell death in these cells. These results suggested that FGFR2 loss might be prone to highly effective CHK1i treatment. In conclusion, extreme cellular dependency of ERK activation may imply a possible application for the MEK1/2 inhibitor, either as a single inhibitor or in combination with CHK1i in MYCN-amplified neuroblastomas.

Loss of p53 suppresses replication stress-induced DNA damage in ATRX-deficient neuroblastoma.

Genetic aberrations are present in the ATRX gene in older high-risk neuroblastoma (NB) patients with very poor clinical outcomes. Its loss-of-function (LoF) facilitates the alternative lengthening of telomeres (ALT) pathway in tumor cells and is strongly linked to replication stress (RS) and DNA damage through G-quadruplex (G4) DNA secondary structures. However, limited information is available on ATRX alteration-related NB tumorigenesis. We herein knocked out (KO) ATRX in MYCN-amplified (NGP) and MYCN single copy (SK-N-AS) NB cells with wild-type (wt) and truncated TP53 at the C terminus, respectively, using CRISPR/Cas9 technologies. The loss of ATRX increased DNA damage and G4 formation related to RS in TP53 wt isogenic ATRX KO NGP cells, but not in SK-N-AS clones. A gene set enrichment analysis (GSEA) showed that the gene sets related to DNA double-strand break repair, negative cell cycle regulation, the G2M checkpoint, and p53 pathway activation were enriched in NGP clones. The accumulation of DNA damage activated the ATM/CHK2/p53 pathway, leading to cell cycle arrest in NGP clones. Interestingly, ATRX loss did not induce RS related to DNA damage response (DDR) in TP53-truncated SK-N-AS cells. p53 inactivation abrogated cell cycle arrest and reduced G4 accumulation in NGP clones. The loss of p53 also induced G4 DNA helicases or Fanconi anemia group D2 protein (FANCD2) with ATRX deficiency, suggesting that ATRX maintained genome integrity and p53 deficiency attenuated RS-induced DNA damage in NB cells featuring inactivated ATRX by regulating DNA repair mechanisms and replication fork stability.

FANCI functions as a repair/apoptosis switch in response to DNA crosslinks.

Cells counter DNA damage through repair or apoptosis, yet a direct mechanism for this choice has remained elusive. When facing interstrand crosslinks (ICLs), the ICL-repair protein FANCI heterodimerizes with FANCD2 to initiate ICL excision. We found that FANCI alternatively interacts with a pro-apoptotic factor, PIDD1, to enable PIDDosome (PIDD1-RAIDD-caspase-2) formation and apoptotic death. FANCI switches from FANCD2/repair to PIDD1/apoptosis signaling in the event of ICL-repair failure. Specifically, removing key endonucleases downstream of FANCI/FANCD2, increasing ICL levels, or allowing damaged cells into mitosis (when repair is suppressed) all suffice for switching. Reciprocally, apoptosis-committed FANCI reverts from PIDD1 to FANCD2 after a failed attempt to assemble the PIDDosome. Monoubiquitination and deubiquitination at FANCI K523 impact interactor selection. These data unveil a repair-or-apoptosis switch in eukaryotes. Beyond ensuring the removal of unrepaired genomes, the switch's bidirectionality reveals that damaged cells can offset apoptotic defects via de novo attempts at lesion repair.

Acceleration or Brakes: Which Is Rational for Cell Cycle-Targeting Neuroblastoma Therapy?

Unrestrained proliferation is a common feature of malignant neoplasms. Targeting the cell cycle is a therapeutic strategy to prevent unlimited cell division. Recently developed rationales for these selective inhibitors can be subdivided into two categories with antithetical functionality. One applies a "brake" to the cell cycle to halt cell proliferation, such as with inhibitors of cell cycle kinases. The other "accelerates" the cell cycle to initiate replication/mitotic catastrophe, such as with inhibitors of cell cycle checkpoint kinases. The fate of cell cycle progression or arrest is tightly regulated by the presence of tolerable or excessive DNA damage, respectively. This suggests that there is compatibility between inhibitors of DNA repair kinases, such as PARP inhibitors, and inhibitors of cell cycle checkpoint kinases. In the present review, we explore alterations to the cell cycle that are concomitant with altered DNA damage repair machinery in unfavorable neuroblastomas, with respect to their unique genomic and molecular features. We highlight the vulnerabilities of these alterations that are attributable to the features of each. Based on the assessment, we offer possible therapeutic approaches for personalized medicine, which are seemingly antithetical, but both are promising strategies for targeting the altered cell cycle in unfavorable neuroblastomas.

The Prognostic Impact of Eosinophils and the Eosinophil-to-Lymphocyte Ratio on Survival Outcomes in Stage II Resectable Pancreatic Cancer.

OBJECTIVES: The relationship between eosinophils and cancer prognosis is unknown. Therefore, we analyzed the relationship between circulating eosinophils and the survival of stage IIA and IIB pancreatic cancer patients who underwent surgical resection. METHODS: This study included a retrospective cohort of 67 consecutive patients. Patients were categorized into two different groups based on the optimal cutoff for pretreatment levels of each biomarker, according to the receiver operating characteristic curves. RESULTS: The Kaplan-Meier method showed that low eosinophil (P = 0.0403), high neutrophil (P = 0.0066), and high monocyte (P = 0.0003) counts were associated with short overall survival (OS). Low lymphocyte-to-monocyte ratio (P = 0.0194) and eosinophil-to-lymphocyte ratio (ELR) (P = 0.0413) were associated with reduced OS. In multivariate analysis, histological differentiation (P = 0.0014), high neutrophils (P = 0.047), high monocytes (P = 0.029), and low eosinophils (P < 0.0001) were correlated with poorer OS. Histological differentiation (P = 0.033), low lymphocyte-to-monocyte ratio (P = 0.029), and low ELR (P = 0.005) were correlated with poor OS and were significant independent prognostic factors of poor outcomes. CONCLUSIONS: Low eosinophils and low ELR were significant independent prognostic factors of poor outcomes.

High levels of human epididymis protein 4 mRNA and protein expression are associated with chemoresistance and a poor prognosis in pancreatic cancer.

Pancreatic cancer is associated with an exceedingly poor prognosis, warranting the development of novel therapeutic strategies and discovery of prognostic predictors. Given that chemoresistance­related molecules are reportedly associated with the poor prognosis of pancreatic cancer, the present study aimed to identify molecules that could be efficacious therapeutic targets for pancreatic cancer. First, 10 patient­derived xenografts (PDXs) were established from patients with pancreatic cancer. Subsequently, after treating tumor tissue generated from the PDXs with standard drugs, next­generation sequencing (NGS) was performed using these tissues. The results of NGS analysis and immunohistochemical analysis on 80 pancreatic cancer tissues revealed that human epididymis protein 4 (HE4) expression in the anticancer drug­treated PDX group was higher than that in the untreated PDXs. In addition, chemoresistance ability was observed in tumor cell lines overexpressing HE4. Furthermore, Kaplan­Meier analysis of tumor tissues from 80 patients with pancreatic cancer was performed and it was found that patients with a high HE4 expression level had a poor survival rate compared with those who had a low HE4 expression level. Multivariate analysis also indicated the high expression level of HE4 was an independent poor prognostic biomarker. Thus, it was concluded that high gene and protein expression levels of HE4 mediate chemoresistance and are independent prognostic factors for pancreatic cancer.

A high number of PD-L1+ CD14+ monocytes in peripheral blood is correlated with shorter survival in patients receiving immune checkpoint inhibitors.

PURPOSE: Targeting of anti-programmed cell death protein-1 (PD-1) and anti-programmed death-ligand 1 (PD-L1) is a standard therapeutic strategy for various cancers. The aim of the present study was to investigate the prognostic effect of pretreatment PD-L1 expression levels in peripheral blood mononuclear cell (PBMC) subsets for patients with several cancer types receiving anti-PD-1 blockade therapies. PATIENTS AND METHODS: Thirty-two patients undergoing anti-PD-L1 blockade therapy, including 15 with non-small cell lung cancer, 14 with gastric cancer, 1 with melanoma, 1 with parotid cancer, and 1 with bladder cancer, were recruited for the present study. PD-L1 expression levels in CD3+, CD4+, CD8+, CD45RA+ and CCR7+ T cells; CD20+ B cells; CD14+ and CD16+ monocytes were measured via flow cytometry before treatment. The percentages of PD-L1+ cells in respective PBMC subsets were compared with respect to different clinicopathological conditions and the association with overall survival (OS) was assessed. RESULTS: The percentages of PD-L1+ with CD3+, CD4+ and CD8+ T cells including naïve and memory T cell subsets, or CD20+ B cells during pretreatment were not markedly correlated with the OS of patients (p > 0.05); however, the percentage of the PD-L1+ CD14+ monocyte subset was significantly correlated with OS (p = 0.0426). CONCLUSION: Increase in pretreatment expression levels of PD-L1 on CD14+ monocytes is associated with the OS of patients treated with immune checkpoint inhibitors. Further evaluation of large sample size and each specific cancer type might clarify the predictive role of PBMC in patients.

CEP131 Abrogates CHK1 Inhibitor-Induced Replication Defects and Is Associated with Unfavorable Outcome in Neuroblastoma.

Checkpoint kinase 1 (CHK1) plays a key role in genome surveillance and integrity throughout the cell cycle. Selective inhibitors of CHK1 (CHK1i) are undergoing clinical evaluation for various human malignancies, including neuroblastoma. Recently, we reported that CHK1i, PF-477736, induced a p53-mediated DNA damage response. As a result, the cancer cells were able to repair DNA damage and became less sensitive to CHK1i. In this study, we discovered that PF-477736 increased expression of MDM2 oncogene along with CHK1i-induced replication defects in neuroblastoma NB-39-nu cells. A mass spectrometry analysis of protein binding to MDM2 in the presence of CHK1i identified the centrosome-associated family protein 131 (CEP131), which was correlated with unfavorable prognosis of neuroblastoma patients. We revealed that MDM2 was associated with CEP131 protein degradation, whereas overexpression of CEP131 accelerated neuroblastoma cell growth and exhibited resistance to CHK1i-induced replication defects. Thus, these findings may provide a future therapeutic strategy against centrosome-associated oncogenes involving CEP131 as a target in neuroblastoma.

High expression levels of polymeric immunoglobulin receptor are correlated with chemoresistance and poor prognosis in pancreatic cancer.

Pancreatic cancer has extremely poor prognosis, warranting the discovery of novel therapeutic and prognostic markers. The expression of polymeric immunoglobulin receptor (pIgR), a key component of the mucosal immune system, is increased in several cancers. However, its clinical relevance in pancreatic cancer remains unclear. In the present study, the prognostic value of pIgR in pancreatic cancer patients after surgical resection was assessed and it was determined that the expression of pIgR was correlated with poor prognosis. Ten pancreatic cancer patient­derived xenograft (PDX) lines were established, followed by next­generation sequencing of tumor tissues from these lines after standard chemotherapy. Immunohistochemical analysis of chemoresistance­related molecules using 77 pancreatic cancer tissues was also performed. The expression of pIgR mRNA in the PDX group treated with anticancer drugs was higher than in the untreated group. High pIgR expression in tissue specimens from 77 pancreatic cancer patients was significantly associated with poor prognosis and was revealed to be an independent prognostic factor, predicting poor outcomes. High pIgR mRNA and protein levels were independent prognostic factors, indicating that pIgR could be a novel predictor for poor prognosis of pancreatic cancer patients.

High expression of olfactomedin-4 is correlated with chemoresistance and poor prognosis in pancreatic cancer.

Pancreatic cancer has an extremely poor prognosis, and identification of novel predictors of therapeutic efficacy and prognosis is urgently needed. Chemoresistance-related molecules are correlated with poor prognosis and may be effective targets for cancer treatment. Here, we aimed to identify novel molecules correlated with chemoresistance and poor prognosis in pancreatic cancer. We established 10 patient-derived xenograft (PDX) lines from patients with pancreatic cancer and performed next-generation sequencing (NGS) of tumor tissues from PDXs after treatment with standard drugs. We established a gene-transferred tumor cell line to express chemoresistance-related molecules and analyzed the chemoresistance of the established cell line against standard drugs. Finally, we performed immunohistochemical (IHC) analysis of chemoresistance-related molecules using 80 pancreatic cancer tissues. From NGS analysis, we identified olfactomedin-4 (OLFM4) as having high expression in the PDX group treated with anticancer drugs. In IHC analysis, OLFM4 expression was also high in PDXs administered anticancer drugs compared with that in untreated PDXs. Chemoresistance was observed by in vitro analysis of tumor cell lines with forced expression of OLFM4. In an assessment of tissue specimens from 80 patients with pancreatic cancer, Kaplan-Meier analysis showed that patients in the low OLFM4 expression group had a better survival rate than patients in the high OLFM4 expression group. Additionally, multivariate analysis showed that high expression of OLFM4 was an independent prognostic factor predicting poor outcomes. Overall, our study revealed that high expression of OLFM4 was involved in chemoresistance and was an independent prognostic factor in pancreatic cancer. OLFM4 may be a candidate therapeutic target in pancreatic cancer.

Plasma Levels of Soluble PD-L1 Correlate With Tumor Regression in Patients With Lung and Gastric Cancer Treated With Immune Checkpoint Inhibitors.

BACKGROUND/AIM: Cancer immune therapy by immune checkpoint inhibitors (ICIs) is a promising therapeutic strategy for various cancer types. Among ICIs, anti-programmed cell death protein-1 (PD1) and anti-programmed death-ligand 1 (PD-L1) antibodies have shown a remarkable clinical benefit. The present study aimed to address the functional and clinical significance of serum levels of soluble PD-L1 (sPD-L1) in patients. MATERIALS AND METHODS: A total of 21 patients, 11 with NSCLC, nine with gastric cancer and one with bladder cancer, who underwent anti-PD-1 therapy were evaluated for sPD-L1 concentration by ELISA analyses at diagnosis and after treatment. RESULTS: Pretreatment levels of sPD-L1 in patients who received ICIs were not remarkably correlated with the overall survival of these patients (r=0.3394, p=0.1323). Reduction of plasma sPD-L1 level was significantly correlated with tumor regression in patients administered four cycles of treatment (p<0.05). CONCLUSION: sPD-L1 might be derived and secreted from tumors and might be useful to identify primary responders to ICIs at a relatively early treatment timepoint.