Deletion of the TMEM30A gene enables leukemic cell evasion of NK cell cytotoxicity.

Natural killer (NK) cell immunotherapy has gained attention as a promising strategy for treatment of various malignancies. In this study, we used a genome-wide CRISPR screen to identify genes that provide protection or susceptibility to NK cell cytotoxicity. The screen confirmed the role of several genes in NK cell regulation, such as genes involved in interferon-γ signaling and antigen presentation, as well as genes encoding the NK cell receptor ligands B7-H6 and CD58. Notably, the gene TMEM30A, encoding CDC50A-beta-subunit of the flippase shuttling phospholipids in the plasma membrane, emerged as crucial for NK cell killing. Accordingly, a broad range of TMEM30A knock-out (KO) leukemia and lymphoma cells displayed increased surface levels of phosphatidylserine (PtdSer). TMEM30A KO cells triggered less NK cell degranulation, cytokine production and displayed lower susceptibility to NK cell cytotoxicity. Blockade of PtdSer or the inhibitory receptor TIM-3, restored the NK cell ability to eliminate TMEM30A-mutated cells. The key role of the TIM-3 - PtdSer interaction for NK cell regulation was further substantiated by disruption of the receptor gene in primary NK cells, which significantly reduced the impact of elevated PtdSer in TMEM30A KO leukemic cells. Our study underscores the potential significance of agents targeting the interaction between PtdSer and TIM-3 in the realm of cancer immunotherapy.

HLA-B*44 and the Bw4-80T motif are associated with poor outcome of relapse-preventive immunotherapy in acute myeloid leukemia.

HLA-B alleles are associated with outcomes in various pathologies, including autoimmune diseases and malignancies. The encoded HLA-B proteins are pivotal in antigen presentation to cytotoxic T cells, and some variants containing a Bw4 motif also serve as ligands to the killer immunoglobulin-like receptors (KIR) 3DL1/S1 of NK cells. We investigated the potential impact of HLA-B genotypes on the efficacy of immunotherapy for relapse prevention in acute myeloid leukemia (AML). Seventy-eight non-transplanted AML patients receiving HDC/IL-2 in the post-consolidation phase were genotyped for HLA-B and KIR genes. HLA-B*44 heralded impaired LFS (leukemia-free survival) and overall survival (OS), but the negative association with outcome was not shared across alleles of the HLA-B44 supertype. Notably, HLA-B*44 is one of few HLA-B44 supertype alleles containing a Bw4 motif with a threonine at position 80, which typically results in weak binding to the inhibitory NK receptor, KIR3DL1. Accordingly, a strong interaction between KIR3DL1 and Bw4 was associated with superior LFS and OS (p = 0.014 and p = 0.027, respectively). KIR3DL1+ NK cells from 80 T-Bw4 donors showed significantly lower degranulation responses and cytokine responses than NK cells from 80I-Bw4 donors, suggesting impaired KIR3DL1-mediated education in 80 T-Bw4 subjects. We propose that presence of a strong KIR3DL1+-Bw4 interaction improves NK cell education and thus is advantageous in AML patients receiving HDC/IL-2 immunotherapy for relapse prevention.