Melanoma treatment has been revolutionized by antibody-based immunotherapies. IFNγ secretion by CD8⁺ T cells is critical for therapy efficacy having anti-proliferative and pro-apoptotic effects on tumour cells. Our study demonstrates a genetic evolution of IFNγ resistance in different melanoma patient models. Chromosomal alterations and subsequent inactivating mutations in genes of the IFNγ signalling cascade, most often JAK1 or JAK2, protect melanoma cells from anti-tumour IFNγ activity. JAK1/2 mutants further evolve into T-cell-resistant HLA class I-negative lesions with genes involved in antigen presentation silenced and no longer inducible by IFNγ. Allelic JAK1/2 losses predisposing to IFNγ resistance development are frequent in melanoma. Subclones harbouring inactivating mutations emerge under various immunotherapies but are also detectable in pre-treatment biopsies. Our data demonstrate that JAK1/2 deficiency protects melanoma from anti-tumour IFNγ activity and results in T-cell-resistant HLA class I-negative lesions. Screening for mechanisms of IFNγ resistance should be considered in therapeutic decision-making.

Malignant cells express ligands for the natural killer cell immunoreceptor NKG2D, which sensitizes to early recognition and elimination by cytotoxic lymphocytes and provides an innate barrier against tumor development. However, the mechanisms that control NKG2D ligand (NKG2DL) expression in tumor cells remain unknown. We recently identified the NKG2DL ULBP2 as strong prognostic marker in human malignant melanoma. Here, we provide evidence that the tumor-suppressive microRNAs (miRNA) miR-34a and miR-34c control ULBP2 expression. Reporter gene analyses revealed that both miRNAs directly targeted the 3′-untranslated region of ULBP2 mRNA and that levels of miR-34a inversely correlated with expression of ULBP2 surface molecules. Accordingly, treatment of cancer cells with miRNA inhibitors led to upregulation of ULBP2, whereas miR-34 mimics led to downregulation of ULBP2, diminishing tumor cell recognition by NK cells. Treatment with the small molecule inhibitor Nutlin-3a also decreased ULBP2 levels in a p53-dependent manner, which was due to a p53-mediated increase in cellular miR-34 levels. Taken together, our study shows that tumor-suppressive miR-34a and miR-34c act as ULBP2 repressors. These findings also implicate p53 in ULBP2 regulation, emphasizing the role of the specific NKG2DL in tumor immune surveillance. Cancer Res; 72(2); 460–71. ©2011 AACR.

Purpose: CD8+ T lymphocytes can kill autologous melanoma cells, but their activity is impaired when poorly immunogenic tumor phenotypes evolve in the course of disease progression. Here, we analyzed three consecutive melanoma lesions obtained within one year of developing stage IV disease for their recognition by autologous T cells. Experimental Design: One skin (Ma-Mel-48a) and two lymph node (Ma-Mel-48b, Ma-Mel-48c) metastases were analyzed for T-cell infiltration. Melanoma cell lines established from the respective lesions were characterized, determining the T-cell–stimulatory capacity, expression of surface molecules involved in T-cell activation, and specific genetic alterations affecting the tumor–T-cell interaction. Results: Metastases Ma-Mel-48a and Ma-Mel-48b, in contrast with Ma-Mel-48c, were infiltrated by T cells. The T-cell–stimulatory capacity was found to be strong for Ma-Mel-48a, lower for Ma-Mel-48b, and completely abrogated for Ma-Mel-48c cells. The latter proved to be HLA class I–negative due to an inactivating mutation in one allele of the beta-2-microglobulin (B2M) gene and concomitant loss of the other allele by a deletion on chromosome 15q. The same deletion was already present in Ma-Mel-48a and Ma-Mel-48b cells, pointing to an early acquired genetic event predisposing to development of β2m deficiency. Notably, the same chronology of genetic alterations was also observed in a second β2m-deficient melanoma model. Conclusion: Our study reveals a progressive loss in melanoma immunogenicity during the course of metastatic disease. The genetic evolvement of T-cell resistance suggests screening tumors for genetic alterations affecting immunogenicity could be clinically relevant in terms of predicting patient responses to T-cell–based immunotherapy. Clin Cancer Res; 20(24); 6593–604. ©2014 AACR.

Myeloid derived suppressor cells (MDSCs) suppress innate and adaptive immunity, thereby limiting anti‐tumor immune responses in cancer patients. In patients with advanced melanoma, the phenotype and function of MDSCs remains controversial. In our study, we further explored two distinct subpopulations of MDSCs and investigated the impact of Vemurafenib on these cells. Flow cytometry analysis revealed that in comparison to healthy donors and patients with localized disease, PBMCs from patients with metastatic melanoma showed an increased frequency of CD14⁺HLA‐DR^−/low monocytic MDSCs (moMDSCs) and of a previously unrecognized population of CD14⁻CD66b⁺Arginase1⁺ granulocytic MDSCs (grMDSCs). In vitro, both populations suppressed autologous T‐cell proliferation, which was tested in CFSE‐based proliferation assays. Vemurafenib treatment of melanoma patients reduced the frequency of both moMDSCs and grMDSCs. According to our in vivo finding, conditioned medium (CM) from Vemurafenib treated melanoma cells was less active in inducing moMDSCs in vitro than CM from untreated melanoma cells. In conclusion, patients with advanced melanoma show increased levels of moMDSCs, and of a population of CD14⁻CD66b⁺Arginase1⁺ grMDSCs. Both MDSCs are distinct populations capable of suppressing autologous T‐cell responses independently of each other. In vitro as well as in vivo, Vemurafenib inhibits the generation of human moMDSCs. Thus, Vemurafenib decreases immunosuppression in patients with advanced melanoma, indicating its potential as part of future immunotherapies.

Antibodies targeting the immune checkpoint molecules PD-1, PD-L1 and CTLA-4, administered alone or in combination with chemotherapy, are the standard of care in most patients with metastatic non-small-cell lung cancers. When given before curative surgery, tumor responses and improved event-free survival are achieved. New antibody combinations may be more efficacious and tolerable. In an ongoing, open-label phase 2 study, 60 biomarker-unselected, treatment-naive patients with resectable non-small-cell lung cancer were randomized to receive two preoperative doses of nivolumab (anti-PD-1) with or without relatlimab (anti-LAG-3) antibody therapy. The primary study endpoint was the feasibility of surgery within 43 days, which was met by all patients. Curative resection was achieved in 95% of patients. Secondary endpoints included pathological and radiographic response rates, pathologically complete resection rates, disease-free and overall survival rates, and safety. Major pathological (≤10% viable tumor cells) and objective radiographic responses were achieved in 27% and 10% (nivolumab) and in 30% and 27% (nivolumab and relatlimab) of patients, respectively. In 100% (nivolumab) and 90% (nivolumab and relatlimab) of patients, tumors and lymph nodes were pathologically completely resected. With 12 months median duration of follow-up, disease-free survival and overall survival rates at 12 months were 89% and 93% (nivolumab), and 93% and 100% (nivolumab and relatlimab). Both treatments were safe with grade ≥3 treatment-emergent adverse events reported in 10% and 13% of patients per study arm. Exploratory analyses provided insights into biological processes triggered by preoperative immunotherapy. This study establishes the feasibility and safety of dual targeting of PD-1 and LAG-3 before lung cancer surgery.ClinicalTrials.gov Indentifier: NCT04205552.

Recent studies suggest that BRAF^V600-mutated melanomas in particular respond to dual anti-programmed cell death protein 1 (PD-1) and anti-cytotoxic T lymphocyte-associated protein 4 (CTLA-4) immune checkpoint inhibition (ICI). Here we identified an over-representation of interleukin (IL)-17–type 17 helper T (T_H17) gene expression signatures (GES) in BRAF^V600-mutated tumors. Moreover, high baseline IL-17 GES consistently predicted clinical responses in dual-ICI-treated patient cohorts but not in mono anti-CTLA-4 or anti-PD-1 ICI cohorts. High IL-17 GES corresponded to tumor infiltration with T cells and neutrophils. Accordingly, high neutrophil infiltration correlated with clinical response specifically to dual ICI, and tumor-associated neutrophils also showed strong IL-17–T_H17 pathway activity and T cell activation capacity. Both the blockade of IL-17A and the depletion of neutrophils impaired dual-ICI response and decreased T cell activation. Finally, high IL-17A levels in the blood of patients with melanoma indicated a higher global T_H17 cytokine profile preceding clinical response to dual ICI but not to anti-PD-1 monotherapy, suggesting a future role as a biomarker for patient stratification.