Natural Killer Cell Killing of Acute Myelogenous Leukemia and Acute Lymphoblastic Leukemia Blasts by Killer Cell Immunoglobulin-Like Receptor–Negative Natural Killer Cells after NKG2A and LIR-1 Blockade

Although the study of natural killer (NK) cell alloreactivity has been dominated by studies of killer cell immunoglobulin-like receptors (KIRs), we hypothesized that NKG2A and LIR-1, present on 53% ± 13% and 36% ± 18% of normal NK cells, respectively, play roles in the NK cell killing of primary leukemia targets. KIR- cells, which compose nearly half of the circulating NK cell population, exhibit tolerance to primary leukemia targets, suggesting signaling through other inhibitory receptors. Both acute myelogenous leukemia and acute lymphoblastic leukemia targets were rendered susceptible to lysis by fresh resting KIR- NK cells when inhibitory receptor–major histocompatibility class I interactions were blocked by pan-HLA antibodies, demonstrating that these cells are functionally competent. Blockade of a single inhibitory receptor resulted in slightly increased killing, whereas combined LIR-1 and NKG2A blockade consistently resulted in increased NK cell cytotoxicity. Dual blockade of NKG2A and LIR-1 led to significant killing of targets by resting KIR- NK cells, demonstrating that this population is not hyporesponsive. Together these results suggest that alloreactivity of a significant fraction of KIR- NK cells is mediated by NKG2A and LIR-1. Thus strategies to interrupt NKG2A and LIR-1 in combination with anti-KIR blockade hold promise for exploiting NK cell therapy in acute leukemias

Circulating Angiogenic Factors Associated with Response and Survival in Patients with Acute Graft-versus-Host Disease: Results from Blood and Marrow Transplant Clinical Trials Network 0302 and 0802

AbstractCirculating angiogenic factors (AF) reflect tissue healing capacity, although some AF can also contribute to inflammation and are indicative of endothelial dysfunction. The AF milieu in acute graft-versus-host disease (aGVHD) has not been broadly characterized. We hypothesized that patients with abundant AF involved in repair/regeneration versus those mediating damage/inflammation would have improved outcomes. Circulating AF known predominantly for repair/regeneration (epidermal growth factor [EGF], fibroblast growth factor-1 and -2, heparin binding–EGF–like growth factor, and vascular endothelial growth factor-A [VEGF-A], -C, and -D) and for damage/inflammation (angiopoietin-2, endothelin-1, soluble endoglin [sEng], follistatin [FS], leptin, and placental growth factor [PlGF]) were measured in a discovery set of hematopoietic cell recipients with grade III and IV aGVHD and compared with controls, then validated in 2 aGVHD cohorts enrolled in Blood and Marrow Transplant Clinical Trials Network (BMT CTN) trials 0302 (n = 105, serum) and 0802 (n = 158, plasma) versus controls without aGVHD (n = 53, serum). Levels of EGF and VEGF-A were lower than in controls at the onset of aGVHD in both trials and higher with complete response to first-line aGVHD therapy in CTN 0802. FS and PlGF were elevated in aGVHD measured in either serum or plasma. At day 28 after initial aGVHD therapy, elevated FS was an independent negative prognostic factor for survival in both cohorts (hazard ratio, 9.3 in CTN 0302; 2.8 in CTN 0802). These data suggest that circulating AF are associated with clinical outcomes after aGVHD and, thus, may contribute to both pathogenesis and recovery

Donor HLA-E Status Associates with Disease-Free Survival and Transplant-Related Mortality after Non In Vivo T Cell-Depleted HSCT for Acute Leukemia

Previous studies have suggested that HLA-E may have a significant role in the outcome of matched unrelated hematopoietic stem cell transplantation (HSCT), especially for patients with acute leukemia. We used Center for International Blood and Marrow Transplant Research data and samples of 1840 adult patients with acute leukemia and their 10/10 HLA-matched unrelated donors to investigate the impact of HLA-E matching status as well as of donor/recipient (D/R) HLA-E genotype on post-HSCT outcome. Both patients and donors were HLA-E genotyped by next-generation sequencing. All patients received their first transplant in complete remission between 2000 and 2015. Median follow-up time was 90 months. Overall survival, disease-free survival (DFS), transplant-related mortality (TRM), and relapse incidence were primary endpoints with statistical significance set at .01. D/R HLA-E genotype analysis revealed a significant association of donor HLA-E*01:03/01:03 genotype with DFS (hazard ratio [HR] = 1.35, P = .0006) and TRM (HR= 1.41, P = .0058) in patients who received T cell replete (ie, without in vivo T cell depletion) transplants (n = 1297). As for D/R HLA-E matching, we did not identify any significant effect on any of the clinical outcome endpoints. In conclusion, this is the largest study to date reporting an improvement of DFS and TRM after matched unrelated HSCT by avoidance of HLA-E*01:03 homozygous donors in patients transplanted with T cell replete grafts for acute leukemia

Therapeutic manipulation of innate lymphoid cells

Since their relatively recent discovery, innate lymphoid cells (ILCs) have been shown to be tissue-resident lymphocytes that are critical mediators of tissue homeostasis, regeneration, and pathogen response. However, ILC dysregulation contributes to a diverse spectrum of human diseases, spanning virtually every organ system. ILCs rapidly respond to environmental cues by altering their own phenotype and function as well as influencing the behavior of other local tissue-resident cells. With a growing understanding of ILC biology, investigators continue to elucidate mechanisms that expand our ability to phenotype, isolate, target, and expand ILCs ex vivo. With mounting preclinical data and clinical correlates, the role of ILCs in both disease pathogenesis and resolution is evident, justifying ILC manipulation for clinical benefit. This Review will highlight areas of ongoing translational research and critical questions for future study that will enable us to harness the full therapeutic potential of these captivating cells