Donor Killer Immunoglobulin-Like Receptor Profile Bx1 Imparts a Negative Effect and Centromeric B-Specific Gene Motifs Render a Positive Effect on Standard-Risk Acute Myeloid Leukemia/Myelodysplastic Syndrome Patient Survival after Unrelated Donor Hematopoietic Stem Cell Transplantation

Investigation of KIR/HLA relationship and other clinical variables after T-cell-replete haploidentical bone marrow transplantation in patients with acute myeloid leukemia (AML)

BACKGROUND

KIR/HLA mismatch in hematopoietic stem cell transplantation (HSCT), particularly in patients with acute myeloid leukemia (AML), was related to decreased recurrence rates, improved engraftment, and a reduction in graft-versus-host disease, according to recent research (GVHD). Uncertainty exists about the impact of KIR/HLA mismatch on haploidentical-HSCTs treated with post-transplant cyclophosphamide (PTCy). We attempted to analyze the effects of KIR/HLA mismatch on clinical outcomes on transplant outcomes using the cohort of 54 AML patients who received a haplo-HSCT with PTCy.

RESULTS

In contrast to KIR/HLA match, our findings showed that donor KIR/HLA mismatch was substantially associated with superior OS (HR, 2.92; (P = 0.04)). Moreover, donor KIR/HLA mismatch (KIR2DS1_D/C2⁺ _R and KIR2DS2_D/C1⁺ _R mismatch versus KIR2DL1_D/C2^- _R mm, KIR2DL2/3_D/C1^- _R mm and KIR3DL1_D/Bw4^- mm) was correlated with the improvements in OS (HR, 0.74; P = 0.085) and activating. KIR/HLA mismatch versus KIR/HLA match was significantly correlated with improvements in OS (HR, .46; P = 0.03) and inhibitory. KIR/HLA mismatch versus KIR/HLA match was enhancement in the OS (HR, .93; P = 0.06). Despite a higher rate of aGvHD (grade I-IV) in the patients with KIR/HLA mismatch compared to KIR/HLA matched (57% vs. 33% (p = 0.04). However, the KIR/HLA mismatch group saw a decreased relapse rate (3.2% vs. 23%, p = 0.04).

CONCLUSION

This analysis shows the significance of KIR/HLA Incompatibility, other clinical variables like CMV, the relationship between donor/recipient and donor age, and the relationship between donor/recipient and donor age in the haplo-donor selection process. It also suggests that KIR and HLA mismatching between donor and recipient could be routinely performed for haplo-donor selection and may improve clinical outcomes after haplo-HSCTs with PTCy.

Impact of natural killer cell’s functional reconstruction on the results of allogeneic hematopoietic stem cell transplantation

Introduction. Currently, more and more attention is being paid to possible strategies for preventing the development of graft-versus-host disease (GVHD) and reducing the risk of infections while maintaining the antitumor effect — graft-versus-leukemia effect (GVL). In this context, the study of natural killer cells (NK-cells) seems to be quite promising.

Aim – to analyze the biological and functional properties of NK-cells after allo-HSCT, their reconstitution after transplantation and factors affecting this process, as well as the mechanisms of alloreactivity of NK cells in patients after allo-HSCT. Main findings. Various types of activating or inhibiting receptors, which are expressed on NK-cells, regulate the functions of NK-cells. Among them, the main role is played by the killer immunoglobin-like receptor (KIR-receptor), which mediates tolerance to one’s own cells and the immune response, both antitumor and directed against infectious agents. NK-cells can play a decisive role in preventing early relapses and infectious complications, as they are among the first to recover after allo-HSCT. They also have the ability to eliminate the recipient’s T-cells and antigen presenting cells (APCs), thereby preventing the development of graft failure and GVHD. There are several models of NK alloreactivity based on KIR; however, the results of studies in this area are contradictory. This review summarizes the available literature data.

Dynamic mRNA expression of donor-derived activating KIR genes and their significant effects on clinical outcome after haematopoietic stem cell transplantation

Numerous reports suggest that activating killer immunoglobulin-like receptors (aKIRs) of natural killer (NK) cells, in addition to inhibitory KIRs (iKIRs), play a prognostic role after allogeneic haematopoietic stem cell transplantation (allo-HSCT). We aimed to investigate the association between the dynamic expression of KIRs on NK cells and the outcomes, particularly regarding graft-versus-host disease (GvHD). This study retrospectively enrolled 260 pairs of donors and recipients who had undergone allo-HSCT without in-vitro T cell depletion. The mRNA transcription level of KIRs was determined by quantitative real-time polymerase chain reaction (RT-qPCR). The levels of aKIR transcripts were decreased more than those of iKIRs during the occurrence of GvHD. The transcription levels of KIR2DS2 and KIR2DS4 in the patients developing GvHD, compared with those who were at a tolerance state, showed the most significant decrease in the month at their peak transcription levels (p = 0.03, p = 0.002). Significantly decreased expression of KIR2DS1 (p = 0.02), KIR2DS3 (p = 0.04) and KIR2DS5 (p = 0.04) in the GvHD group was observed when the transcription level reached a maximum. High expression of KIR3DS1 was associated with superior overall survival (OS) (p < 0.001). The expression of KIR2DS4 in the KIR genotype Bx group decreased more during GvHD, particularly at 3M (p = 0.02). These findings suggest that KIR genes are potential post-HSCT biomarkers and dynamic changes in the KIR transcription levels can be detected to better predict the occurrence and evaluate the treatment of GvHD after transplantation.

Adaptive Admixture of HLA Class I Allotypes Enhanced Genetically Determined Strength of Natural Killer Cells in East Asians

Human natural killer (NK) cells are essential for controlling infection, cancer, and fetal development. NK cell functions are modulated by interactions between polymorphic inhibitory killer cell immunoglobulin-like receptors (KIR) and polymorphic HLA-A, -B, and -C ligands expressed on tissue cells. All HLA-C alleles encode a KIR ligand and contribute to reproduction and immunity. In contrast, only some HLA-A and -B alleles encode KIR ligands and they focus on immunity. By high-resolution analysis of KIR and HLA-A, -B, and -C genes, we show that the Chinese Southern Han (CHS) are significantly enriched for interactions between inhibitory KIR and HLA-A and -B. This enrichment has had substantial input through population admixture with neighboring populations, who contributed HLA class I haplotypes expressing the KIR ligands B*46:01 and B*58:01, which subsequently rose to high frequency by natural selection. Consequently, over 80% of Southern Han HLA haplotypes encode more than one KIR ligand. Complementing the high number of KIR ligands, the CHS KIR locus combines a high frequency of genes expressing potent inhibitory KIR, with a low frequency of those expressing activating KIR. The Southern Han centromeric KIR region encodes strong, conserved, inhibitory HLA-C-specific receptors, and the telomeric region provides a high number and diversity of inhibitory HLA-A and -B-specific receptors. In all these characteristics, the CHS represent other East Asians, whose NK cell repertoires are thus enhanced in quantity, diversity, and effector strength, likely augmenting resistance to endemic viral infections.

BSHI guideline: HLA matching and donor selection for haematopoietic progenitor cell transplantation

A review of the British Society for Histocompatibility and Immunogenetics (BSHI) Guideline 'HLA matching and donor selection for haematopoietic progenitor cell transplantation' published in 2016 was undertaken by a BSHI appointed writing committee. Literature searches were performed and the data extracted were presented as recommendations according to the GRADE nomenclature.

Diversity of KIRs in invasive breast cancer patients and healthy controls along with the clinical significance in ER/PR/HER2+ patients

Killer cell immunoglobulin-like receptors (KIR) consists of activating and inhibitory genes are essential for natural killer cell education. To determine the association of KIRs with susceptibility to invasive Breast cancer (BC), genotyping of 16 KIRs was performed by sequence-specific primers-polymerase chain reaction in 226 confirmed cases of BC with defined estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor 2 (HER2) status and 226 healthy controls (CNs). We observed a lower frequency of 2DL1 and 2DS4del along with increased frequency of 2DS4fl in cases compared to CNs. Further analysis revealed a higher frequency of KIR2DL2, 2DS1, 2DS2,3DS1 in ER+ cases, 2DL2, 2DL5 in PR+ and 2DL1 in HER2+ cases compared to CNs. The detrimental role of KIR2DS4fl was observed in ER+ and PR+ cases whereas 2DS4del confers protection against ER+, PR+, and HER2+ cases. We noted the predisposing role of Bx genotype, KIR2DS1, 2DS2, 2DS5, 2DL2, 2DL5 for lymphatic invasion in ER+ cases along with a higher rate of lymph node metastasis (LNM) in carriers of Bx genotype and KIR2DS1 in ER+ cases. We suggest a link between B haplotype associated genes with the increased risk of lymphatic invasion and LNM, particularly in ER+ cases of BC.

Influence of KIR and NK Cell Reconstitution in the Outcomes of Hematopoietic Stem Cell Transplantation

Natural killer (NK) cells play a significant role in immune tolerance and immune surveillance. Killer immunoglobin-like receptors (KIRs), which recognize human leukocyte antigen (HLA) class I molecules, are particularly important for NK cell functions. Previous studies have suggested that, in the setting of hematopoietic stem cell transplantation (HSCT), alloreactive NK cells from the donor could efficiently eliminate recipient tumor cells and the residual immune cells. Subsequently, several clinical models were established to determine the optimal donors who would exhibit a graft-vs. -leukemia (GVL) effect without developing graft-vs. -host disease (GVHD). In addition, hypotheses about specific beneficial receptor-ligand pairs and KIR genes have been raised and the favorable effects of alloreactive NK cells are being investigated. Moreover, with a deeper understanding of the process of NK cell reconstitution post-HSCT, new factors involved in this process and the defects of previous models have been observed. In this review, we summarize the most relevant literatures about the impact of NK cell alloreactivity on transplant outcomes and the factors affecting NK cell reconstitution.

Study of KIR gene expression at the mRNA level in specific donor-derived NK cells after allogeneic HSCT

The function of natural killer (NK) cells after allogeneic hematopoietic stem cell transplantation (allo-HSCT) is regulated by the balance between inhibitory KIRs (iKIRs) and activating KIRs (aKIRs). However, few studies have examined the subsequent expression of KIR genes unique to the donor. We defined the set of KIR genes expressed only in the donor and designed a method for measuring the expression of these KIR genes by quantitative real-time polymerase chain reaction (RT-qPCR) based on genetic cloning techniques. In this study, we evaluated the recovery pattern of KIR genes in 252 donor-recipient pairs. The expression of each KIR unique to the donor was in line with that of KIR genes shared by the donor and recipient, such as KIR2DS1, KIR3DS1, KIR2DS4, or KIR2DS3. The timing of the peak mRNA expression of aKIRs unique to the donor was inconsistent but occurred within the first 3 months posttransplantation, whereas the peak mRNA expression of iKIRs was consistently observed in the third month after transplantation. The expression of KIR2DL2 in the third month posttransplantation was significantly higher in the transplant recipients than in the donors (p = 0.01). The KIR2DL1 and KIR3DL1 levels in the transplant recipients in the second and third months posttransplantation were also obviously higher than the donor levels (p < 0.0001). Thus, these observations should be considered when attempting to predict the correlation between mRNA expression and prognosis after allo-HSCT.

Cryopreserved Human Natural Killer Cells Exhibit Potent Antitumor Efficacy against Orthotopic Pancreatic Cancer through Efficient Tumor-Homing and Cytolytic Ability (Running Title: Cryopreserved NK Cells Exhibit Antitumor Effect)

Pancreatic cancer is known to be highly aggressive, and desmoplasia-induced accumulation of extracellular matrix (ECM), which is a hallmark of many pancreatic cancers, severely restricts the therapeutic efficacy of both immunotherapeutics and conventional chemotherapeutics due to the ECM functioning as a major physical barrier against permeation and penetration. In the case of cell-based immunotherapeutics, there are several other bottlenecks preventing translation into clinical use due to their biological nature; for example, poor availability of cell therapeutic in a readily usable form due to difficulties in production, handling, shipping, and storage. To address these challenges, we have isolated allogeneic natural killer (NK) cells from healthy donors and expanded them in vitro to generate cryopreserved stocks. These cryopreserved NK cells were thawed to evaluate their therapeutic efficacy against desmoplastic pancreatic tumors, ultimately aiming to develop a readily accessible and mass-producible off-the-shelf cell-based immunotherapeutic. The cultured NK cells post-thawing retained highly pure populations of activated NK cells that expressed various activating receptors and a chemokine receptor. Furthermore, systemic administration of NK cells induced greater in vivo tumor growth suppression when compared with gemcitabine, which is the standard chemotherapeutic used for pancreatic cancer treatment. The potent antitumor effect of NK cells was mediated by efficient tumor-homing ability and infiltration into desmoplastic tumor tissues. Moreover, the infiltration of NK cells led to strong induction of apoptosis, elevated expression of the antitumor cytokine interferon (IFN)-γ, and inhibited expression of the immunosuppressive transforming growth factor (TGF)-β in tumor tissues. Expanded and cryopreserved NK cells are strong candidates for future cell-mediated systemic immunotherapy against pancreatic cancer.

Selecting the Best Donor for Haploidentical Transplant: Impact of HLA, Killer Cell Immunoglobulin-Like Receptor Genotyping, and Other Clinical Variables

The use of post-transplant cyclophosphamide (PTCy)-based haploidentical (haplo) transplant is increasing worldwide. However, because multiple potential haplo donors are usually available, data-driven guidance is clearly needed to help transplant centers prioritize donors. To that end, we retrospectively analyzed 208 consecutive donor-recipient pairs receiving PTCy-based haplo transplant at a single institution. Median recipient and donor age were 52 years (range, 19 to 75) and 38 years (range, 15 to 73), peripheral blood stem cell was the stem cell source in 66%, and myeloablative conditioning was used in 41%. Median follow-up for surviving patients was 33 months (range, 7 to 130). Donor variables analyzed included age, sex, relationship, cytomegalovirus (CMV) status, ABO compatibility, HLA disparity, and several natural killer (NK) alloreactivity models. Multivariate Cox analysis was used to adjust for known patient, disease, and transplant covariates. Donor characteristics independently associated with improved survival included presence of HLA-DR mismatch, HLA-DP nonpermissive mismatch, killer cell immunoglobulin-like receptor (KIR) receptor-ligand mismatch, and KIR B/x haplotype with KIR2DS2. Donor characteristics associated with inferior survival included parental donor relationship and the use of a CMV-seronegative donor for a CMV-seropositive patient. Increased HLA disparity (≥4/10 HLA allelic mismatches [graft-versus-host direction]) resulted in relapse protection at the expense of increased nonrelapse mortality with no associated survival effect. We further propose a donor risk factor scoring system to permit a more evidence-based selection algorithm for potential haplo donors. This large, single-institution analysis demonstrates the importance of HLA-DR/HLA-DP disparity, NK alloreactivity, and other clinical variables in the haplo donor selection process and suggests that KIR and HLA-DP genotyping should be performed routinely for haplo donor selection.

[Immune reconstruct regularity profile of KIR2DL1 and KIR3DL1 in unrelated-donor allogeneic hematopoietic stem cell transplantation]

Objective: To investigate the immune reconstruct regularity profile of KIR2DL1 and KIR3DL1 in unrelated-donor allogeneic hematopoietic stem cell transplantation (allo-HSCT) with KIR-AA genotype. Method: 75 donor-recipient pairs were performed by KIR genotying using PCR-SSP, and all donors were identified with KIR-AA genotype. Dynamic detections (including unrelated-donor on the day of transplantation and the recipient each month post allo-HSCT) of the expression of KIR2DL1/3DL1 on NK cell and mRNA level were performed in 291 cases using flow cytometry (FCM) and real-time fluorescent quantitation PCR (RT-qPCR) . Result: ①The median expression of KIR2DL1 in unrelated-donor on transplant's day was 21.60%, the median expression of KIR2DL1 in recipient 1M, 2M, 3M and 3-6M after transplantation were 7.40%, 12.00%, 16.92%, 17.64% respectively. The median expression of KIR2DL1 in unrelated-donor on transplant's day was 265.14 copies/10 000abl copies, the median expression of KIR2DL1 in recipient 1M, 2M, 3M, 3-6M, 6-9M, 9-12M after transplantation were 332.17, 438.31, 723.25, 414.17, 180.76 and 234.67 copies/10 000abl copies respectively. The median expression of KIR2DL1 on NK cells and mRNA level gradually increased at all time points after transplantation, and reached the highest expression at 3 months after transplantation. But mRNA expression levels increased earlier than NK cell membrane proteins. ②The median expression of KIR3DL1 in unrelated-donors on transplant's day was 18.56%, the median expression of KIR3DL1 in recipient 1M, 2M, 3M, 3-6M after transplantation were 23.83%, 22.57%, 23.02%, 21.60% respectively. The median expression of KIR3DL1 in unrelated-donor on transplant's day was 572.29 copies/10 000abl copies, the median expression of KIR3DL1 in recipient 1M, 2M, 3M, 3-6M, 6-9M, 9-12M after transplantation were 1 233.74, 1 140.42, 876.73, 1 057.07, 739.02 and 514.43 copies/10 000abl copies respectively. The median expression of KIR3DL1 on NK cells and mRNA level were higher than donors at 1 month after transplantation, and stable expression at all time points after transplantation, so mRNA and NK cell membrane proteins expression increased at the same time. Conclusion: The immune reconstruct regularity of KIR2DL1 and KIR3DL1 gene were different, which provided an experimental basis for selecting the best time to detect the expressions of KIR2DL1 and 3DL1 after transplantation.

Engineering Natural Killer Cells for Cancer Immunotherapy

The past several years have seen tremendous advances in the engineering of immune effector cells as therapy for cancer. While chimeric antigen receptors (CARs) have been used extensively to redirect the specificity of autologous T cells against hematological malignancies with striking clinical results, studies of CAR-modified natural killer (NK) cells have been largely preclinical. In this review, we focus on recent advances in NK cell engineering, particularly on preclinical evidence suggesting that NK cells may be as effective as T cells in recognizing and killing targets after genetic modification. We will discuss strategies to introduce CARs into both primary NK cells and NK cell lines in an effort to provide antigen specificity, the challenges of manufacturing engineered NK cells, and evidence supporting the effectiveness of this approach from preclinical and early-phase clinical studies using CAR-engineered NK cells. CAR-NK cells hold great promise as a novel cellular immunotherapy against refractory malignancies. Notably, NK cells can provide an "off-the-shelf" product, eliminating the need for a personalized and patient-specific product that plagues current CAR-T cell therapies. The ability to more potently direct NK cell-mediated cytotoxicity against refractory tumors through the expression of CAR is likely to contribute to the recent paradigm shift in cancer treatment.

[Distribution of donor-specific aKIR after unrelated allogeneic hematopoietic stem cell transplantation]

Objective: To analyze the distribution and proportion of donor-specific activated killer cell immunoglobulin like receptor (aKIR) genes and their clinical application values in unrelated allogeneic hematopoietic stem cell transplantation (allo-HSCT) . Methods: Retrospective analyses of KIR genotyping using polymerase chain reaction with sequence specific primers (PCR-SSP) were performed in 216 pairs of donors and recipients. Results: The frequency of donor-specific KIR genes was 53.7% (116/216) in 216 patients receiving unrelated allo-HSCT, with the frequency of 78.3% (112/143) in the KIR genes mismatched group and 5.5% (4/73) in matched group. Of the 116 patients with detectable donor-specific KIR genes, 99.1% (115/116) patients had various donor-specific aKIR genes. Among 55 pairs of donors' KIR-Bx genotype and patients' KIR-AA genotype group, the most commonly observed genotypes were Bx1, Bx2, Bx3, Bx4, in which the donor-specific KIR genes were respectively KIR 3DS1, 2DL5A, 2DS5, 2DS1; KIR 3DS1, 2DL5A, 2DS3, 2DS1; KIR 2DS2, 2DL2; KIR 2DS2, 2DL2, 3DS1, 2DL5A, 2DS5, 2DS1. Of 44 pairs of donors' KIR-AA genotype and patients' KIR-Bx (AB) genotype group, 36.4% (16/44) recipients had donor-specific KIR2DS4 (FUL) gene. In 143 pairs of KIR mismatched group, the frequencies of donor-specific KIR genes were KIR2DS1 (35.7%) , KIR3DS1 (32.9%) , KIR2DS5 (29.4%) , KIR2DS4 (FUL) (25.9%) , KIR2DL2 (25.2%) , KIR2DS2 (24.5%) , KIR2DS3 (21.7%) and KIR3DL1 (8.4%) , respectively. Conclusion: The donor-specific aKIR genes mainly existed in KIR mismatched group after unrelated allo-HSCT, and the different pairs of donors' and patients' KIR genotypes led to the diverse donor-specific aKIR. But there were higher specific aKIR genes in higher frequency of KIR AA, Bx1, Bx2, Bx3, Bx4 genotypes. All these can provide the experimental basis for studying the role of the donor-specific aKIR genes on the prognosis of HSCT.

Integrating Genomics in Myelodysplastic Syndrome to Predict Outcomes After Allogeneic Hematopoietic Cell Transplantation

Myelodysplastic syndrome (MDS) is a heterogeneous group of clonal hematopoietic neoplastic disorders most commonly occurring in the elderly population; MDS has a tendency to progress to acute leukemia. Although epigenetic therapies have improved the outcomes of MDS patients, allogeneic hematopoietic cell transplantation remains the only curative option. Molecular characterization of MDS using next-generation sequencing has expanded not only the knowledge on MDS but also the depth of understanding of evolution and contribution of recurrent somatic mutations in precursor conditions. Rapidly evolving genomic information on MDS may provide clinicians with better risk stratification tools and may also aid in supplying useful information to allow comprehensive therapeutic decision making for MDS patients. In this concise review, we summarize the current knowledge and understanding of recurrent somatic mutations in MDS and discuss salient genomic information predicting response and influencing therapeutic outcomes in the context of allogeneic hematopoietic cell transplantation, as well as the potential application of these findings into future clinical practice.