Accurate predictive markers of therapeutic efficacy are needed to optimize patient selection, improve treatment decision-making and minimize costs

Accurate predictive markers of therapeutic efficacy are needed to optimize patient selection, improve treatment decision-making and minimize costs. tumours can be identified by melanoma-specific immunohistochemistry using commercially available antibodies for HLA-DR to improve anti-PD-1 patient selection. Monoclonal antibodies blocking the programmed death-1 (PD-1) receptor or its ligand (PD-L1) relieve the suppression of anti-tumour immune responses in a variety of cancers. Durable remissions occur in sizable fractions of patients with melanoma (30C40%)1,2,3,4,5,6, non-small cell lung cancer (15C20%)1,3,7,8,9, renal cell carcinoma (20C30%)1,3,10, bladder urothelial carcinoma (30%)11, Hodgkin’s lymphoma (80C90%)12, as well as others including head and neck squamous-cell carcinoma and triple-negative breast malignancy3,13,14,15. Accurate predictive markers of therapeutic efficacy are needed to optimize patient selection, improve treatment decision-making and minimize costs. To date, several candidate approaches have been identified in melanoma. These include tumour or immune cell expression of PD-L1 (refs 1, 3), identification of neoantigens through next-generation sequencing techniques16,17 and T-cell receptor clonality profiling18. While quite promising, these assays are technically challenging and require specialized tissue processing. Tumours evade immune surveillance by immune checkpoint expression (PD-L1 as well as others), immunosuppressive cytokine profiles, tolerogenic immune cell recruitment (regulatory T-cells as well as others) and cancer-specific cell signalling19,20,21. In addition, malignancy cells can drop the ability to present tumour antigens, thus avoiding recognition by cytotoxic T cells and antigen presenting cells, thus avoiding recognition by cytotoxic T cells and antigen-presenting cells (APCs)22. Downregulation of major histocompatibility complex Toceranib (PHA 291639, SU 11654) class-I and -II (MHC-I and MHC-II) has been linked to immune suppression, metastatic progression and a poor prognosis in numerous malignancies22,23,24,25,26. Despite the established importance of tumour-specific antigen expression, the influence of MHC-I and MHC-II expression on response to new immune therapies, particularly anti-PD-1/PD-L1, has not been explored. Specifically, HLA-DR is frequently expressed on melanoma and has unclear functional and prognostic significance27,28,29. We hypothesized that MHC-I and MHC-II expression, particularly HLA-DR, are required for anti-PD-1/PD-L1 activity and serve as technically and clinically feasible predictive biomarkers for therapeutic efficacy. In this study, we find that melanoma-specific expression of HLA-DR marks tumours with unique inflammatory signals that are more responsive to PD-1-targeted therapy. On the basis of this, we propose use of tumour-specific HLA-DR expression as a potential biomarker of high likelihood of response to these brokers in clinical trials. Results MHC-I and MHC-II expression in melanoma cell lines On the basis of the known biological interactions of PD-1/PD-L1-signalling, antigen presentation by tumour or professional APCs is usually hypothesized to be a requirement for immune Rabbit Polyclonal to GRIN2B (phospho-Ser1303) recognition of the malignant cell. MHC-I presents antigen to CD8+ cytotoxic T lymphocytes (CTL) and is ubiquitously expressed by most cells. Loss of MHC-I is typically thought to trigger natural-killer cell checkpoints, resulting in natural-killer cell-mediated cytotoxicity. In contrast, MHC-II, which presents antigen to CD4+ T-helper cells, is typically restricted to professional APCs such as dendritic cells and B cells. HLA-DR, the primary antigen-presenting Toceranib (PHA 291639, SU 11654) molecule of the MHC-II pathway is usually expressed in some cancers, particularly in response to CTL-secreted interferon-gamma (IFN). Some data suggest that non-immune cells, including cancer cells, can function as MHC-II+ APCs30,31,32. Given the heterogeneity of the tumour milieu, we asked whether MHC-I and II were expressed in cell line models of melanoma (rather than in resected melanoma tumours), where the contribution of stromal and infiltrating immune cells could be excluded. Using the Cancer Cell Line Encyclopaedia (CCLE) melanoma panel of 60 cell lines, we decided that MHC-I mRNA expression (using as the prototype) was ubiquitously high across almost all melanoma cell lines (Fig. 1a). In contrast, mRNA (using an arbitrary cutoff of 6 (RMA log2 signal intensity), there was a signature of 159 genes (Supplementary Data 1) which were significantly altered (up or downregulated, false-discovery rate Toceranib (PHA 291639, SU 11654) (FDR) 1%) in mRNA (Fig. 1b). Clustering on these genes suggested four clusters of expression patterns, which we identified as clusters Ia and Ib (predominantly HLA-DR-expressing) and clusters II and III (predominantly HLA-DR-negative). Gene set analysis (GSA) of the CCLE based on MHC-II classification yielded 27 gene sets with upregulated scores and 1 with a downregulated score at an FDR5% in.