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Despite impressive clinical success, cancer immunotherapy based on immune checkpoint blockade remains ineffective in many patients due to tumoral resistance. Here we use the autochthonous TiRP melanoma model, which recapitulates the tumoral resistance signature observed in human melanomas. TiRP tumors resist immunotherapy based on checkpoint blockade, cancer vaccines or adoptive T-cell therapy. TiRP tumors recruit and activate tumor-specific CD8 + T cells, but these cells then undergo apoptosis. This does not occur with isogenic transplanted tumors, which are rejected after adoptive T-cell therapy. Apoptosis of tumor-infiltrating lymphocytes can be prevented by interrupting the Fas/Fas-ligand axis, and is triggered by polymorphonuclear-myeloid-derived suppressor cells, which express high levels of Fas-ligand and are enriched in TiRP tumors. Blocking Fas-ligand increases the anti-tumor efficacy of adoptive T-cell therapy in TiRP tumors, and increases the efficacy of checkpoint blockade in transplanted tumors. Therefore, tumor-infiltrating lymphocytes apoptosis is a relevant mechanism of immunotherapy resistance, which could be blocked by interfering with the Fas/Fas-ligand pathway.

Background: Ipilimumab (Ipi) improves the survival of advanced melanoma patients with an incremental long-term benefit in 10-15 % of patients. A tumor signature that correlates with this survival benefit could help optimizing individualized treatment strategies., Methods: Freshly frozen melanoma metastases were collected from patients treated with either Ipi alone (n: 7) or Ipi combined with a dendritic cell vaccine (TriMixDC-MEL) (n: 11). Samples were profiled by immunohistochemistry (IHC), whole transcriptome (RNA-seq) and methyl-DNA sequencing (MBD-seq)., Results: Patients were divided in two groups according to clinical evolution: durable benefit (DB; 5 patients) and no clinical benefit (NB; 13 patients). 20 metastases were profiled by IHC and 12 were profiled by RNA- and MBD-seq. 325 genes were identified as differentially expressed between DB and NB. Many of these genes reflected a humoral and cellular immune response. MBD-seq revealed differences between DB and NB patients in the methylation of genes linked to nervous system development and neuron differentiation. DB tumors were more infiltrated by CD8(+) and PD-L1(+) cells than NB tumors. B cells (CD20(+)) and macrophages (CD163(+)) co-localized with T cells. Focal loss of HLA class I and TAP-1 expression was observed in several NB samples., Conclusion: Combined analyses of melanoma metastases with IHC, gene expression and methylation profiling can potentially identify durable responders to Ipi-based immunotherapy.

Representational difference analysis, a cDNA subtraction approach, was used to identify genes that are expressed in acute leukemia but not in normal hematological tissues. We isolated a cDNA fragment from a cell line derived from a B cell acute lymphoblastic leukemia bearing two Philadelphia chromosomes. The cDNA derives from an orphan gene that was named BLACE. BLACE is located in region 7q36 and encodes a major 5.3-kb transcript and several alternatively spliced minor transcripts. Significant expression of BLACE was detected by RT-PCR and quantitative RT-PCR in bone marrow samples from B cell acute lymphoblastic leukemia patients. BLACE was not or was scarcely expressed in other types of hematological malignancies, in normal tissues, and in solid tumors. [Copyright &y& Elsevier]