PD-L1 Is a Therapeutic Target of the Bromodomain Inhibitor JQ1 and, Combined with HLA Class I, a Promising Prognostic Biomarker in Neuroblastoma

Abstract

This study sought to evaluate the expression of programmed cell death-ligand-1 (PD-L1) and HLA class I on neuroblastoma cells and programmed cell death-1 (PD-1) and lymphocyte activation gene 3 (LAG3) on tumor-infiltrating lymphocytes to better define patient risk stratification and understand whether this tumor may benefit from therapies targeting immune checkpoint molecules. IHC staining for PD-L1, HLA class I, PD-1, and LAG3 was assessed in 77 neuroblastoma specimens, previously characterized for tumor-infiltrating T-cell density and correlated with clinical outcome. Surface expression of PD-L1 was evaluated by flow cytometry and IHC in neuroblastoma cell lines and tumors genetically and/or pharmacologically inhibited for MYC and MYCN. A dataset of 477 human primary neuroblastomas from GEO and ArrayExpress databases was explored for PD-L1, MYC, and MYCN correlation. Multivariate Cox regression analysis demonstrated that the combination of PD-L1 and HLA class I tumor cell density is a prognostic biomarker for predicting overall survival in neuroblastoma patients ( = 0.0448). MYC and MYCN control the expression of PD-L1 in neuroblastoma cells both and Consistently, abundance of PD-L1 transcript correlates with MYC expression in primary neuroblastoma. The combination of PD-L1 and HLA class I represents a novel prognostic biomarker for neuroblastoma. Pharmacologic inhibition of MYCN and MYC may be exploited to target PD-L1 and restore an efficient antitumor immunity in high-risk neuroblastoma. .

JQ1, a BET‐bromodomain inhibitor, inhibits human cancer growth and suppresses PD‐L1 expression

“…It has been reported to suppress the growth of pancreatic ductal adenocarcinoma in patient‐derived xenograft models (Garcia et al, ). It also suppresses the growth of ovarian cancer and neuroblastoma (Zhu et al, ; Hogg et al, ; Melaiu et al, ), but the underlying mechanism is still unknown. Furthermore, JQ1 inhibits cell growth by suppressing PD‐L1 expression in ovarian cancer.…”

“…Specific BET inhibitors including JQ1 have been developed (Filippakopoulos and Knapp, ). JQ1 has also been reported to suppress PD‐L1 expression in ovarian cancer and neuroblastoma (Zhu et al, ; Melaiu et al, ). In the present study, therefore, we investigated the effects of JQ1 on cell growth, and mRNA and protein levels of PD‐L1 in renal cell carcinoma primary culture cells, and prostate, liver, and lung cancer cell lines.…”

Tumor-infiltrating T cells and PD-L1 expression in childhood malignant extracranial germ-cell tumors

“…31 Immunohistochemistry and manual acquisition IHC was conducted with 4 μm of formaldehyde-fixed paraffinembedded tissues sections. 24 Following deparaffinization and antigen retrieval with EnVision FLEX Target retrieval solution at low or high pH (citrate buffer pH 6.1 and Tris/EDTA pH 9.0, respectively) with PT-link (Dako), slides were subjected to the avidin/ biotin blocking system (Thermo Fisher Scientific, Fremont, CA, USA) according to manufacturer's instructions. For single staining, slide were incubated (60 min at room temperature) with monoclonal antibodies (mAb) against CD3 (F7.2.38, Dako), CD4 (1F6, Leica Microsystems), CD8 (C8/144B, Dako), FOXP3 (clone 236A/E7, Abcam), PD-1 (NAT105, ScyTek Laboratories), and PD-L1 (RBT-PDL1, Bio SB).…”

“…[17][18][19][20] PD-L1 expression has been investigated in many malignancies, including breast, kidney, lung, esophagus, ovary, colorectal, head and neck, squamous cell carcinomas, melanomas, GISTs, gliomas and neuroblastoma. [21][22][23][24][25] Very little is known about the expression of PD-L1 and the density of TILs subsets in pediatric and adolescent malignant extracranial germ-cell tumors (meGCTs), a heterogeneous group of tumors representing 3-5% of all childhood cancers occurring before 15 years of age, and 15% of neoplasms in adolescents aged 15-19 years. 26,27 MeGCTs derive from primordial germ cells (PGC) and can occur both within and outside the gonads.…”

The Prognostic Significance of Soluble Programmed Death Ligand 1 Expression in Cancers: A Systematic Review and Meta‐analysis

“…However, the current status of cancer is that the 5-year survival rate is still low. Thus, there is an urgent need to identify reliable biomarkers to help early diagnosis, prevention and treatment of cancers [2,3].…”