Longitudinal NK cell kinetics and cytotoxicity in children with neuroblastoma enrolled in a clinical phase II trial.

BACKGROUND: Natural killer (NK) cells are one of the main effector populations of immunotherapy with monoclonal antibody and cytokines, used in combination with chemotherapy to treat children with high-risk neuroblastoma on this phase II trial. However, the impact of chemoimmunotherapy on NK cell kinetics, phenotype, and function is understudied. METHODS: We prospectively examined NK cell properties from 63 children with newly diagnosed neuroblastoma enrolled in a phase II trial (NCT01857934) and correlated our findings with tumor volume reduction after 2 courses of chemoimmunotherapy. NK cell studies were conducted longitudinally during chemoimmunotherapy and autologous hematopoietic cell transplantation (autoHCT) with optional haploidentical NK cell infusion and additional immunotherapy. RESULTS: Chemoimmunotherapy led to significant NK cytopenia, but complete NK cell recovery reliably occurred by day 21 of each therapy course as well as after autoHCT. Haploidentical NK cell infusion elevated the NK cell count transiently during autoHCT. NK cell cytotoxicity increased significantly during treatment compared with diagnosis. In addition, NK cells maintained their ability to respond to cytokine stimulation in culture longitudinally. Unsupervised cluster analysis of CD56bright NK cell count and tumor volume at diagnosis and after two courses of chemoimmunotherapy identified two patient groups with distinct primary tumor sizes and therapy responses. CONCLUSION: After profound NK cytopenia due to chemoimmunotherapy, endogenously reconstituted NK cells exhibit enhanced NK cytotoxicity compared with pretherapy measurements. Our data suggest a relationship between CD56bright expression and tumor size before and after two courses of chemoimmunotherapy; however, future studies are necessary to confirm this relationship and its predictive significance. TRIAL REGISTRATION NUMBER: NCT01857934.

A phase II clinical trial of adoptive transfer of haploidentical natural killer cells for consolidation therapy of pediatric acute myeloid leukemia.

Consolidation therapies for children with intermediate- or high-risk acute myeloid leukemia (AML) are urgently needed to achieve higher cure rates while limiting therapy-related toxicities. We determined if adoptive transfer of natural killer (NK) cells from haploidentical killer immunoglobulin-like receptor (KIR)-human leukocyte antigen (HLA)-mismatched donors may prolong event-free survival in children with intermediate-risk AML who were in first complete remission after chemotherapy. Patients received cyclophosphamide (Day - 7), fludarabine (Days - 6 through - 2), and subcutaneous interleukin-2 (Days - 1, 1, 3, 5, 7, and 9). Purified, unmanipulated NK cells were infused on Day 0, and NK cell chimerism and phenotyping from peripheral blood were performed on Days 7, 14, 21, and 28. As primary endpoint, the event-free survival was compared to a cohort of 55 patients who completed chemotherapy and were in first complete remission but did not receive NK cells. Donor NK cell kinetics were determined as secondary endpoints. Twenty-one patients (median age at diagnosis, 6.0 years [range, 0.1-15.3 years]) received a median of 12.5 × 106 NK cells/kg (range, 3.6-62.2 × 106 cells/kg) without major side effects. All but 3 demonstrated transient engraftment with donor NK cells (median peak donor chimerism, 4% [range, 0-43%]). KIR-HLA-mismatched NK cells expanded in 17 patients (81%) and contracted in 4 (19%). However, adoptive transfer of NK cells did not decrease the cumulative incidence of relapse (0.393 [95% confidence interval: 0.182-0.599] vs. 0.35 [0.209-0.495]; P = .556) and did not improve event-free (60.7 ± 10.9% vs. 69.1 ± 6.8%; P = .553) or overall survival (84.2 ± 8.5% vs. 79.1 ± 6.6%; P = .663) over chemotherapy alone. The lack of benefit may result from insufficient numbers and limited persistence of alloreactive donor NK cells but does not preclude its potential usefulness during other phases of therapy, or in combination with other immunotherapeutic agents. TRIAL REGISTRATION: www.clinicaltrials.gov , NCT00703820 . Registered 24 June 2008.

TOX2 regulates human natural killer cell development by controlling T-BET expression.

Thymocyte selection-associated high mobility group box protein family member 2 (TOX2) is a transcription factor belonging to the TOX family that shares a highly conserved high mobility group DNA-binding domain with the other TOX members. Although TOX1 has been shown to be an essential regulator of T-cell and natural killer (NK) cell differentiation in mice, little is known about the roles of the other TOX family members in lymphocyte development, particularly in humans. In this study, we found that TOX2 was preferentially expressed in mature human NK cells (mNK) and was upregulated during in vitro differentiation of NK cells from human umbilical cord blood (UCB)-derived CD34(+) cells. Gene silencing of TOX2 intrinsically hindered the transition between early developmental stages of NK cells, whereas overexpression of TOX2 enhanced the development of mNK cells from UCB CD34(+) cells. We subsequently found that TOX2 was independent of ETS-1 but could directly upregulate the transcription of TBX21 (encoding T-BET). Overexpression of T-BET rescued the TOX2 knockdown phenotypes. Given the essential function of T-BET in NK cell differentiation, TOX2 therefore plays a crucial role in controlling normal NK cell development by acting upstream of TBX21 transcriptional regulation.

NK cell genotype and phenotype at diagnosis of acute lymphoblastic leukemia correlate with postinduction residual disease.

PURPOSE: Not all natural killer (NK) cells are equally cytotoxic against leukemia because of differences in receptor gene content and surface expression. We correlated NK cell genotype and phenotype at diagnosis of childhood acute lymphoblastic leukemia (ALL) with minimal residual disease (MRD) after induction chemotherapy. EXPERIMENTAL DESIGN: The NK cells and leukemia blasts of 244 patients were analyzed at diagnosis by killer-cell immunoglobulin-like receptor (KIR) typing and immunophenotyping. The results were correlated statistically with postinduction MRD status. RESULTS: The odds of being MRD positive in patients with KIR telomeric (Tel)-A/B genotype were 2.85 times the odds in those with Tel-A/A genotype (P = 0.035). MRD-positive patients were more likely to have KIR2DL5A (P = 0.006) and expressed less activating receptor NKp46 and FASL on their NK cells (P = 0.0074 and P = 0.029, respectively). The odds of being MRD positive increased by 2.01-fold for every percentage increase in NK cells expressing KIR2DL1 in the presence of HLA-C2 ligand (P = 0.034). The quantity of granzyme B inhibitor PI-9 in the leukemia blasts was greater in patients who were MRD positive (P = 0.038). Collectively, five NK cell-related factors (Tel-B-associated KIR2DL5A, NKp46, FASL, granzyme B, and PI-9) are strongly associated with MRD positivity at the end of induction with 100% sensitivity and 80% specificity. CONCLUSIONS: Our data support the hypothesis that NK cells with a strong effector phenotype in the setting of decreased leukemia resistance are associated with better leukemia control.

Multiplex and genome-wide analyses reveal distinctive properties of KIR+ and CD56+ T cells in human blood.

Killer cell Ig-like receptors (KIRs) on NK cells have been linked to a wide spectrum of health conditions such as chronic infections, autoimmune diseases, pregnancy complications, cancers, and transplant failures. A small subset of effector memory T cells also expresses KIRs. In this study, we use modern analytic tools including genome-wide and multiplex molecular, phenotypic, and functional assays to characterize the KIR(+) T cells in human blood. We find that KIR(+) T cells primarily reside in the CD56(+) T population that is distinctively DNAM-1(high) with a genome-wide quiescent transcriptome, short telomere, and limited TCR excision circles. During CMV reactivation in bone marrow transplant recipients, KIR(+)CD56(+) T cells rapidly expanded in real-time but not KIR(+)CD56(-) T cells or KIR(+) NK cells. In CMV(+) asymptomatic donors, as much as 50% of CD56(+) T cells are KIR(+), and most are distinguishably KIR2DL2/3(+)NKG2C(+)CD57(+). Functionally, the KIR(+)CD56(+) T cell subset lyses cancer cells and CMVpp65-pulsed target cells in a dual KIR-dependent and TCR-dependent manner. Analysis of metabolic transcriptome confirms the immunological memory status of KIR(+)CD56(+) T cells in contrast to KIR(-)CD56(+) T cells that are more active in energy metabolism and effector differentiation. KIR(-)CD56(+) T cells have >25-fold higher level of expression of RORC than the KIR(+) counterpart and are a previously unknown producer of IL-13 rather than IL-17 in multiplex cytokine arrays. Our data provide fundamental insights into KIR(+) T cells biologically and clinically.

Ex vivo activation of CD56(+) immune cells that eradicate neuroblastoma.

Despite the use of intensive contemporary multimodal therapy, the overall survival of patients with high-risk neuroblastoma is still less than 50%. Therefore, immunotherapy without cross-resistance and overlapping toxicity has been proposed. In this study, we report the development of a novel strategy to specifically activate and expand human CD56(+) (NCAM1) natural killer (NK) immune cells from normal donors and patients with neuroblastoma. Enriched CD56(+) cells from peripheral blood were mixed with CD56(-) fraction at 1:1 ratio and cultured in the presence of OKT3, interleukin (IL)-2, and -15 for five days and then without OKT3 for 16 more days. The final products contained more than 90% CD56(+) cells and could kill neuroblastoma cells effectively that were originally highly resistant to nonprocessed NK cells. Mechanistically, cytolysis of neuroblastoma was mediated through natural cytotoxicity receptor (NCR), DNAX accessory molecule-1 (DNAM-1; CD226), perforin, and granzyme B. Successful clinical scale-up in a good manufacturing practices (GMP)-compliant bioreactor yielded effector cells that in a neuroblastoma xenograft model slowed tumor growth and extended survival without GVHD. Investigation of CD56(+) cells from patients with neuroblastoma revealed a similar postactivation phenotype and lytic activity. Our findings establish a novel and clinically expedient strategy to generate allogeneic or autologous CD56(+) cells that are highly cytotoxic against neuroblastoma with minimal risk of GVHD.

Molecular determinant-based typing of KIR alleles and KIR ligands.

Killer cell immunoglobulin-like receptors (KIRs) regulate NK cell function. KIRs and their HLA ligands are highly polymorphic in nature with substantial allelic polymorphism. At present, there is a lack of an expedient method for KIR and HLA allele typing with relevant functional information. Here, we developed a single-nucleotide polymorphism (SNP) assay to type various allele groups of KIR2DL1 with distinct functional properties based on polymorphism at position 245. We also established a SNP assay to type different KIR ligands based on polymorphism at position 77 in HLA-C and position 83 in HLA-B and -A. Our SNP assays for KIR and KIR ligand typing are much cheaper and faster than existing high-resolution typing. Importantly, our high-throughput methods provide readouts that are informative in predicting NK cell activity in health, disease, and transplantation.

Blood dendritic cells suppress NK cell function and increase the risk of leukemia relapse after hematopoietic cell transplantation.

NK cells play an important role in hematopoietic stem cell transplantation (HCT) and in cross talk with dendritic cells (DCs) to induce primary T cell response against infection. Therefore, we hypothesized that blood DCs should augment NK cell function and reduce the risk of leukemia relapse after HCT. To test this hypothesis, we conducted laboratory and clinical studies in parallel. We found that although, phenotypically, NK cells could induce DC maturation and DCs could in turn increase activating marker expression on NK cells, paradoxically, both BDCA1(+) myeloid DCs and BDCA4(+) plasmacytoid DCs suppressed the function of NK cells. Patients who received an HLA-haploidentical graft containing a larger number of BDCA1(+) DCs or BDCA4(+) DCs had a higher risk of leukemia relapse and poorer survival. Further experiments indicated that the potent inhibition on NK cell cytokine production and cytotoxicity was mediated in part through the secretion of IL-10 by BDCA1(+) DCs and IL-6 by BDCA4(+) DCs. These results have significant implications for future HCT strategies.

NKAML: a pilot study to determine the safety and feasibility of haploidentical natural killer cell transplantation in childhood acute myeloid leukemia.

PURPOSE To conduct a pilot study to determine the safety, feasibility, and engraftment of haploidentical natural killer (NK) cell infusions after an immunosuppressive regimen in children with acute myeloid leukemia (AML). PATIENTS AND METHODS Ten patients (0.7 to 21 years old) who had completed chemotherapy and were in first complete remission of AML were enrolled on the Pilot Study of Haploidentical Natural Killer Cell Transplantation for Acute Myeloid Leukemia (NKAML) study. They received cyclophosphamide (60 mg/kg on day -7) and fludarabine (25 mg/m(2)/d on days -6 through -2), followed by killer immunoglobulin-like receptor-human leukocyte antigen (KIR-HLA) mismatched NK cells (median, 29 x 10(6)/kg NK cells) and six doses of interleukin-2 (1 million U/m(2)). NK cell chimerism, phenotyping, and functional assays were performed on days 2, 7, 14, 21, and 28 after transplantation. Results All patients had transient engraftment for a median of 10 days (range, 2 to 189 days) and a significant expansion of KIR-mismatched NK cells (median, 5,800/mL of blood on day 14). Nonhematologic toxicity was limited, with no graft-versus-host disease. Median length of hospitalization was 2 days. With a median follow-up time of 964 days (range, 569 to 1,162 days), all patients remain in remission. The 2-year event-free survival estimate was 100% (95% CI, 63.1% to 100%). CONCLUSION Low-dose immunosuppression followed by donor-recipient inhibitory KIR-HLA mismatched NK cells is well tolerated by patients and results in successful engraftment. We propose to further investigate the efficacy of KIR-mismatched NK cells in a phase II trial as consolidation therapy to decrease relapse without increasing mortality in children with AML.

Significant functional heterogeneity among KIR2DL1 alleles and a pivotal role of arginine 245.

Killer immunoglobulin-like receptors (KIRs) play an essential role in the regulation of natural killer cell functions. KIR genes are highly polymorphic in nature, showing both haplotypic and allelic variations among people. We demonstrated in both in vitro and in vivo models a significant heterogeneity in function among different KIR2DL1 alleles, including their ability to inhibit YT-Indy cells from degranulation, interferon gamma production, and cytotoxicity against target cells expressing the HLA-Cw6 ligand. Subsequent experiments showed that the molecular determinant was an arginine residue at position 245 (R245) in its transmembrane domain that mechanistically affects both the efficiency of inhibitory signaling and durability of surface expression. Specifically, in comparison with R245-negative alleles, KIR2DL1 that included R245 recruited more Src-homology-2 domain-containing protein tyrosine phosphatase 2 and beta-arrestin 2, showed higher inhibition of lipid raft polarization at immune synapse, and had less down-regulation of cell-surface expression upon interaction with its ligand. Thus, our findings provide novel insights into the molecular determinant of KIR2DL1 and conceivably a fundamental understanding of KIR2DL1 allelic polymorphism in human disease susceptibility, transplant outcome, and donor selection.

Longitudinal analysis of T-cell receptor variable beta chain repertoire in patients with acute graft-versus-host disease after allogeneic stem cell transplantation.

T-cell receptor variable beta chain (TCRBV) repertoire spectratyping involves the estimation of CDR3 length distributions for monitoring T-cell receptor diversity and has proven useful for analyses of immune reconstitution and T-cell clonal expansions in graft-versus-host disease (GVHD) and graft-versus-leukemia after allogeneic stem cell transplantation. We performed a longitudinal spectratype analysis of 23 TCRBV families in 28 patients who underwent allogeneic T cell-depleted peripheral blood stem cell transplantation. Sixteen patients subsequently developed acute GVHD. We recently developed statistical methods that bring increased power and flexibility to spectratype analysis and allow us to analyze TCRBV repertoire development under appropriately complex statistical models. Applying these methods, we found that patients with acute GVHD demonstrated TCRBV repertoire development statistically distinct from that repertoire development in patients without GVHD. Specifically, GVHD patients showed spectratypes indicative of lower diversity and greater deviation from the spectratypes expected in healthy individuals at intermediate times. Most individual TCRBV subfamilies had spectratypes statistically distinguishable between GVHD and non-GVHD patients at 6 months after transplantation. These results suggest that the T-cell receptor repertoire perturbations associated with acute GVHD are widely spread throughout the TCRBV families.

Mobilization of dendritic cells from patients with breast cancer into peripheral blood stem cell leukapheresis samples using Flt-3-Ligand and G-CSF or GM-CSF.

Treatment with myeloablative chemotherapy and autologous peripheral blood stem cell (PBSC) transplantation followed by vaccination with autologous dendritic cells (DCs) treated with tumor antigens is a promising therapeutic strategy for several types of cancer. Obtaining sufficient numbers of both PBSCs and DCs is central to this approach. Previously, it has been shown that administration of Flt-3-Ligand (FL) combined with either G-CSF or GM-CSF mobilizes large numbers of PBSCs in patients with cancer. In the current study, we sought to determine whether these same cytokines could simultaneously mobilize DCs into the PBSC leukapheresis collection. DCs were analysed in PBSC leukapheresis samples obtained from five patients with high-risk breast cancer who received G-CSF alone as priming prior to leukapheresis, four patients who received FL+G-CSF and five patients who received FL+GM-CSF. DCs were defined as cells with a lin(dim/-) HLA-DR+ CD11c+ phenotype. The proportions of DCs in the FL+G-CSF and FL+GM-CSF samples were significantly higher than in pre-mobilization peripheral blood and G-CSF leukapheresis samples. The mean yield of DCs/kg in the FL+GM-CSF samples was also significantly higher than the mean yield of DCs in the G-CSF samples. The FL+G-CSF and FL+GM-CSF mobilized DCs were immature by morphologic and phenotypic criteria but stimulated allogeneic T-cells at levels similar to DCs generated in culture from PBMCs. Overnight culture?of the immature DCs obtained from patients receiving either FL+G-CSF or FL+GM-CSF in TNF-alpha?resulted in the generation of mature DCs. In summary, administration of FL in combination with GM-CSF and G-CSF to patients with breast cancer can mobilize large numbers of immature DCs into PBSC leukapheresis collections.

Nonmyeloablative regimen preserves "niches" allowing for peripheral expansion of donor T-cells.

T-cell recovery following myeloablative preparatory regimens and cord blood transplantation in adult patients gen erally occurs between 1 and 3 years following allogeneic bone marrow transplantation. T-cell reconstitution may involve thymic education of donor-derived precursors or peripheral expansion of mature T-cells transferred in the graft. We measured quantitative and qualitative immunologic reconstitution, T-cell receptor spectratyping, and T-cell receptor excision circle (TREC) levels in adult recipients of umbilical cord blood transplants following a novel nonmyeloablative regimen. These results were compared to previously published results of similar patients receiving a myeloablative regimen and cord blood stem cells. With small numbers of patients treated so far, T-cells (CD3+) reached normal levels in adults 6 to 12 months following nonmyeloablative transplantation compared with 24 months in adults receiving a myeloablative regimen. At 12 months after transplantation, the numbers of phenotypically naive (CD45RA) T-cells were higher in those receiving the nonmyeloablative regimen. The T-cell repertoire in cord blood recipients treated with a nonmyeloablative regimen was markedly more diverse and robust compared with the repertoire in those receiving the myeloablative regimen at similar time points. TRECs (which are generated within the thymus and identify new thymic emigrants and those that have not divided) were detected 12 months after transplantation in the nonmyeloablative recipients, whereas TRECs were not detected in adults until 18 to 24 months in those receiving myeloablative regimens. Thus, in adults receiving a nonmyeloablative preparatory regimen, the quantitative and qualitative recovery of T-cells occurs through rapid peripheral expansion. The ability of patients receiving a nonmyeloablative regimen to recover within a few months suggests that the peripheral niches in which T-cells can proliferate are preserved in these patients compared to those receiving ablative regimens. Moreover, the presence of TREC-positive cells within 1 year suggests that thymic recovery is likewise accelerated in non myeloablative compared to myeloablative regimens.