Prognostic perspectives of PD-L1 combined with tumor-infiltrating lymphocytes, Epstein-Barr virus, and microsatellite instability in gastric carcinomas

Abstract

Background The prognostic potential of PD-L1 is currently unclear in gastric carcinomas, although the immune checkpoint PD-1/PD-L1 inhibitors have produced promising results in clinical trials. Methods We explored the prognostic implications of programmed death ligand 1 (PD-L1) in 514 consecutive surgically-resected gastric carcinomas. Overall survival and recurrence-free survival were evaluated. Immunohistochemistry for PD-L1, CD8, FOXP3, and PD-1, and molecular grouping by in situ hybridization for Epstein-Barr virus (EBV)-encoded small RNAs and multiplex PCR for microsatellite instability (MSI) markers were performed. Additionally, to explore the function inherent to PD-L1, PD-L1-specific siRNA transfection, cell proliferation, invasion, migration and apoptosis assays were conducted in five gastric carcinoma cell lines. Results PD-L1(+) tumor and immune cells were observed in 101 (20%) and 244 patients (47%), respectively. “Tumoral PD-L1(+)/immune cell PD-L1(-)/CD8+/low tumor-infiltrating lymphocytes (TILs),” and more advanced-stage tumors were associated with unfavorable clinical outcomes in the entire cohort through multivariate analysis. Furthermore, tumoral PD-L1(+)/FOXP3+/low TILs were associated with worse clinical outcomes in EBV-positive and MSI-high carcinomas. Tumoral PD-L1(+) alone was an adverse prognostic factor in EBV-positive carcinomas, but not in MSI-high carcinomas, whereas PD-L1(+) immune cells or FOXP3+/high TILs alone were correlated with a favorable prognosis. PD-L1 knockdown in gastric carcinoma cells suppressed cell proliferation, invasion and migration, and increased apoptosis, which were all statistically significant in two EBV(+) cell lines, but not all in three EBV(−) cell lines. Conclusions The prognostic impact of PD-L1 may depend on the tumor microenvironment, and statuses of EBV and MSI, although PD-L1 innately promotes cancer cell survival in cell-based assays. The combination of “tumoral PD-L1/immune cell PD-L1/CD8+ TILs” may serve as an independent prognostic factor. Tumoral PD-L1(+)/immune cell PD-L1(−)/CD8+/low TILs showing a worse prognosis may be beneficial for combinatorial therapies of anti-PD-L1/PD-1 and anti-cytotoxic T-lymphocyte associated antigen 4 (CTLA4) that would promote effector T cells, thus attack the tumor.

Cytotoxic T-lymphocyte infiltration and chemokine predict long-term patient survival independently of tumor mutational burden in triple-negative breast cancer

“… 35 Combination of PD-L1 expression in cancer cells and the number of infiltrating CTLs predicts patient prognosis in gastric cancer. 38 PD-1 positive T cell characteristics, including cytokine and chemokine productions, are different in the tumor (TIL) and in the peripheral blood in lung cancer. 39 Positive stainings of PD-L1 in cancer cells and PD-1 in lymphocytes are associated with aggressive cancer biology, on the other hand, they are also associated with increased pathological complete response to the neoadjuvant chemotherapy in breast cancer.…”

Microsatellite instability and Epstein-Barr virus combined with PD-L1 could serve as a potential strategy for predicting the prognosis and efficacy of postoperative chemotherapy in gastric cancer

“…In the study of De Rosa et al (2018), only 3% PD-L1 + cases were found in MSS/EBV − subgroup and a case was considered positive if membrane immunostaining was present in at least 5% of tumor cells, independently of the intensity. Choi et al (2020) found 14% PD-L1-positive cases in MSS/EBV − when considering both staining intensity and percentage of stained tumor cells, and any membranous staining was regarded as positive expression. In the present study, a higher proportion of PD-L1 + cases in MSS/EBV − group (35%) are reported when scoring PD-L1 expression on the basis of both the intensity and percentage of PD-L1-positive TCs and considering both cell membrane and cytoplasm staining.…”

“…A review of PD-L1 expression in gastric cancer ( Vrna et al, 2018 ) showed that the percentage of PD-L1 + in the TCs ranges from 9% to 49.1% (most of the trials were performed in Asian populations), similar to our results (41.2% in TCs). Previous studies have demonstrated a mutually exclusive relationship between GCs that were EBV-positive and deemed to have MSI ( Choi et al, 2020 ). However, two cases representing both MSI and EBV-positive were observed in a recent study (2/287, 0.70%) ( Pereira et al, 2018 ) and in our study (2/226, 0.88%).…”

“…In recent years, higher PD-L1 expression has been found to be closely associated with EBV-positive and MSI GCs ( Lee et al, 2017 ; Derks et al, 2016 ). However, it is unclear whether the value of PD-L1 expression in predicting GC prognosis is contingent upon EBV and MSI statuses ( Choi et al, 2020 ). Overall, given the complex immune interactions that occur within the tumor microenvironment and available evidence, the addition of PD-L1 expression based on stratification by EBV and MSI statuses would provide better prognostic insight and elucidate the therapeutic implications in GC, whereas the available reports regarding this pattern are insufficient.…”

Whole-Exome Sequencing of Rare Site Endometriosis-Associated Cancer

“…Recently, targeting the immune escape mechanisms of cancer cells and immune checkpoint inhibitor treatment have become the standard for cancer therapy [ 40 ]. Both a high frequency of tumor-infiltrative T cells and PD-1 expression are thought to be potential biomarkers for indicating a response to immune checkpoint inhibitors [ 41 , 42 ]. The high frequency of tumor-infiltrating T cells (revealed by immunostaining of CD8) and the high frequency of PD-1 expression in tumor-infiltrating lymphocytes in the current cases of RSEAC suggest that immune checkpoint inhibitor therapy could also be effective for patients with RSEAC.…”