BRAF inhibitor resistance of melanoma cells triggers increased susceptibility to natural killer cell-mediated lysis

Abstract

BackgroundTargeted therapies and immunotherapies are first-line treatments for patients with advanced melanoma. Serine–threonine protein kinase B-RAF (BRAF) and mitogen-activated protein kinase (MEK) inhibition leads to a 70% response rate in patients with advanced melanoma with a BRAFV600E/K mutation. However, acquired resistance occurs in the majority of patients, leading to relapse. Immunotherapies that activate immune cytotoxic effectors induce long-lasting responses in 30% of patients. In that context, combination of targeted therapies with immunotherapy (IT) is a promising approach. We considered boosting natural killer (NK) cell tumor immunosurveillance, as melanoma cells express stress-induced molecules and activate NK cell lysis.MethodsHere we have generated vemurafenib (a BRAF inihibitor)-resistant (R) cells from BRAFV600E SK28 and M14-sensitive (S) melanoma cell lines and investigated how resistance interferes with immunogenicity to NK cells. We determined the levels of several soluble molecules including NK ligands in 61 melanoma patients at baseline and 6 months M post-treatment with targeted therapies or immunotherapies.ResultsVemurafenib resistance involved activation of p-AKT in SK28R and of p-MEK/p-ERK in M14R cells and was accompanied by modulation of NK ligands. Compared with S cells, SK28R displayed an increased expression of natural killer group 2 D (NKG2D) receptor ligands (major histocompatibility complex class (MHC) I chain-related protein A (MICA) and UL16-binding protein 2 (ULBP2)) whereas M14R exhibited decreased ULBP2 . SK28R and M14R cells induced higher NK degranulation and interferon gamma secretion and were more efficiently lysed by donor and patient NK cells. SK28R showed increased tumor necrosis factor-related apoptosis-inducing ligand receptor II (TRAIL-RII) expression and TRAIL-induced apoptosis, and TRAIL-induced apoptosis of M14R was decreased. Combined BRAF/MEK inhibitors abrogated the growth of SK28S, M14S, and M14R cells, while growth of SK28R was maintained. BRAF/MEK inhibition attenuated NK activity but R cell lines activated polyfunctional NK cells and were lysed with high efficiency. We investigated the relationship of soluble NK ligands and response to treatment in a series of melanoma patients. Soluble NKG2D ligands known to regulate the receptor function have been associated to cancer progression. Serum analysis of patients treated with target therapies or IT indicates that soluble forms of NK ligands (MICA, B7H6, programmed cell death ligand 1, and carcinoembryonic antigen cell adhesion molecule 1) may correlate with clinical response.ConclusionThese results support strategies combining targeted therapies and NK-based immunotherapies.

BRAF as a positive predictive biomarker: Focus on lung cancer and melanoma patients

“…In addition, the combination was not associated with a significantly increase of adverse events of grade 3 or higher respect to vemurafenib alone (65 % vs. 59 %) (Larkin et al, 2014). More recently, in pre-clinical models, it has been highlighted a correlation between the resistance of melanoma cells to BRAF and MEK inhibitors with an increased immunogenicity to natural killer (NK) cells (Frazao et al, 2020). However, due to the possibility of tumor escaping from NK cells activity, a boosting of NK cells may be required in association with targeted therapies to improve antitumor activity (Frazao et al, 2020).…”

Natural Killer Cells and Anti-Cancer Therapies: Reciprocal Effects on Immune Function and Therapeutic Response

“…This suggests that the combination with HDACi could increase the efficacy of BRAFi in an NK cell-dependent manner. Finally, different melanoma cell lines with acquired resistance to vemurafenib and dabrafenib were described to modulate the expression of various NK cell ligands (e.g., MICA/B and HLA-ABC), resulting in higher sensitivity to NK cell lysis compared to the parental cell lines, suggesting patients gaining such resistance might benefit from strategies to enhance NK cell activity [ 197 , 198 ].…”

MAPK inhibitors dynamically affect melanoma release of immune NKG2D-ligands, as soluble protein and extracellular vesicle-associated

“…Our laboratory and others have previously described the effect of vemurafenib on surface expression of NKG2D-L ( López-Cobo et al, 2017 ; Frazao et al, 2017 ). However, even though the effects of BRAFi/MEKi combination on melanoma cell immunogenicity has been previously studied ( Pieper et al, 2018 ; Frazao et al, 2020 ; Harbers et al, 2021 ), little is known about the impact of single MEKi or combined BRAFi/MEKi on the NKG2D system on drug sensitive cells. In addition, the impact of MAPK inhibition on vesicle-released ligands was not studied.…”