Michael R. Verneris

Allogeneic hematopoietic cell transplantation for hematologic malignancy: relative risks and benefits of double umbilical cord blood

Effectiveness of double umbilical cord blood (dUCB) grafts relative to conventional marrow and mobilized peripheral blood from related and unrelated donors has yet to be established. We studied 536 patients at the Fred Hutchinson Cancer Research Center and University of Minnesota with malignant disease who underwent transplantation with an human leukocyte antigen (HLA)-matched related donor (MRD, n = 204), HLA allele-matched unrelated donor (MUD, n = 152) or 1-antigen-mismatched unrelated adult donor (MMUD, n = 52) or 4-6/6 HLA matched dUCB (n = 128) graft after myeloablative conditioning. Leukemia-free survival at 5 years was similar for each donor type (dUCB 51% [95% confidence interval (CI), 41%-59%]; MRD 33% [95% CI, 26%-41%]; MUD 48% [40%-56%]; MMUD 38% [95% CI, 25%-51%]). The risk of relapse was lower in recipients of dUCB (15%, 95% CI, 9%-22%) compared with MRD (43%, 95% CI, 35%-52%), MUD (37%, 95% CI, 29%-46%) and MMUD (35%, 95% CI, 21%-48%), yet nonrelapse mortality was higher for dUCB (34%, 95% CI, 25%-42%), MRD (24% (95% CI, 17%-39%), and MUD (14%, 95% CI, 9%-20%). We conclude that leukemia-free survival after dUCB transplantation is comparable with that observed after MRD and MUD transplantation. For patients without an available HLA matched donor, the use of 2 partially HLA-matched UCB units is a suitable alternative.

Relapse risk after umbilical cord blood transplantation: enhanced graft-versus-leukemia effect in recipients of 2 units

Umbilical cord blood (UCB) transplantation is potentially curative for acute leukemia. This analysis was performed to identify risk factors associated with leukemia relapse following myeloablative UCB transplantation. Acute leukemia patients (n = 177; 88 with acute lymphoblastic leukemia and 89 with acute myeloid leukemia) were treated at a single center. Patients received a UCB graft composed of either 1 (47%) or 2 (53%) partially human leukocyte antigen (HLA)-matched unit(s). Conditioning was with cyclophosphamide and total body irradiation with or without fludarabine. The incidence of relapse was 26% (95% confidence interval [CI], 19%-33%). In multivariate analysis, relapse was higher in advanced disease patients (> or = third complete remission [CR3]; relative risk [RR], 3.6; P < .01), with a trend toward less relapse in recipients of 2 UCB units (RR = 0.6; P = .07). However, relapse was lower for CR1-2 patients who received 2 UCB units (RR 0.5; P < .03). Leukemia-free survival was 40% (95% CI, 30%-51%) and 51% (95% CI, 41%-62%) for single- and double-unit recipients, respectively (P = .35). Although it is known that transplantation in CR1 and CR2 is associated with less relapse risk, this analysis reveals an enhanced graft-versus-leukemia effect in acute leukemia patients after transplantation with 2 partially HLA-matched UCB units. This trial was registered at http://clinicaltrials.gov as NCT00309842.

Advancing animal models of neoplasia through in vivo bioluminescence imaging

Malignant disease is the final manifestation of complex molecular and cellular events leading to uncontrolled cellular proliferation and eventually tissue destruction and metastases. While the in vitro examination of cultured tumour cells permits the molecular dissection of early pathways in tumorigenesis on cellular and subcellular levels, only interrogation of these processes within the complexity of organ systems of the living animal can reveal the full range of pathophysiological changes that occur in neoplastic disease. Such analyses require technologies that facilitate the study of biological processes in vivo, and several approaches have been developed over the last few years. These strategies, in the nascent field of in vivo molecular and cellular imaging, combine molecular biology with imaging modalities as a means to real-time acquisition of functional information about disease processes in living systems. In this review, we will summarise recent developments in in vivo bioluminescence imaging (BLI) and discuss the potential of this imaging strategy for the future of cancer research.

Human cytomegalovirus (CMV)-induced memory-like NKG2C(+) NK cells are transplantable and expand in vivo in response to recipient CMV antigen.

We have previously shown that NKG2C+ NK cells from CMV naive umbilical cord blood grafts expand preferentially in recipients after CMV reactivation, representing a primary NK cell response after hematopoietic cell transplantation. In this study, recipients of adult donor hematopoietic cell transplantation were assessed to evaluate the role of donor/recipient CMV serostatus on the expression and function of NKG2C+ NK cells to determine responses to secondary CMV events. Expansion of NKG2C+ NK cells was seen following clinical CMV reactivation. However, they also expanded in the absence of detectable CMV viremia when both the donor and recipient were CMV seropositive. Upregulation of NKG2C was observed in NK cells from CMV-positive recipients receiving grafts from CMV-seropositive or -seronegative donors. These in vivo–expanded NKG2C+ NK cells had an increased capacity for target cell–induced cytokine production, expressed an inhibitory killer Ig-like receptor for self-HLA and preferentially acquired CD57. Most importantly, NKG2C+ NK cells transplanted from seropositive donors exhibit heightened function in response to a secondary CMV event compared with NKG2C+ NK cells from seronegative donors. We conclude that NKG2C+ memory-like NK cells are transplantable and require active or latent (subclinical) expression of CMV Ag in the recipient for clonal expansion of NK cells previously exposed to CMV in the donor.

Acute graft-versus-host disease after unrelated donor umbilical cord blood transplantation : analysis of risk factors

Acute graft-versus-host disease (GVHD) occurs less frequently after umbilical cord blood transplantation (UCBT). More recent investigations include the use of 2 partially human leukocyte antigen (HLA)-matched UCB units, or double UCB graft, to meet the minimum cell-dose requirement. The purpose of this analysis was to assess the relative risk of acute GVHD in 265 consecutive patients receiving transplants with UCB graft composed of 1 (n = 80) or 2 (n = 185) units. The incidence of grade III-IV acute GVHD was similar between cohorts. However, the incidence of grade II-IV acute GVHD was higher among double UCBT recipients (58 vs 39%, P < .01). Three risk factors for grade II-IV acute GVHD were identified in multiple regression analysis: use of 2 UCB units, use of nonmyeloablative conditioning, and absence of antithymocyte globulin in the conditioning regimen. Transplantation-related mortality (TRM) at 1 year, however, was significantly lower after double UCBT (24 vs 39%, P = .02) even if recipients had grade II-IV acute GVHD (20 vs 39%, P = .05). These data suggest that, despite a higher incidence of grade II acute GVHD in recipients of 2 partially HLA-matched UCB units, there is no adverse effect on TRM. This study is registered at (http://www.clinicaltrials.gov) under the identifiers NCT00305682 and NCT00309842.

Clearance of acute myeloid leukemia by haploidentical natural killer cells is improved using IL-2 diphtheria toxin fusion protein

Haploidentical natural killer (NK) cell infusions can induce remissions in some patients with acute myeloid leukemia (AML) but regulatory T-cell (Treg) suppression may reduce efficacy. We treated 57 refractory AML patients with lymphodepleting cyclophosphamide and fludarabine followed by NK cell infusion and interleukin (IL)-2 administration. In 42 patients, donor NK cell expansion was detected in 10%, whereas in 15 patients receiving host Treg depletion with the IL-2-diphtheria fusion protein (IL2DT), the rate was 27%, with a median absolute count of 1000 NK cells/μL blood. IL2DT was associated with improved complete remission rates at day 28 (53% vs 21%; P = .02) and disease-free survival at 6 months (33% vs 5%; P < .01). In the IL2DT cohort, NK cell expansion correlated with higher postchemotherapy serum IL-15 levels (P = .002), effective peripheral blood Treg depletion (<5%) at day 7 (P < .01), and decreased IL-35 levels at day 14 (P = .02). In vitro assays demonstrated that Tregs cocultured with NK cells inhibit their proliferation by competition for IL-2 but not for IL-15. Together with our clinical observations, this supports the need to optimize the in vivo cytokine milieu where adoptively transferred NK cells compete with other lymphocytes to improve clinical efficacy in patients with refractory AML. This study is registered at clinicaltrials.gov, identifiers: NCT00274846 and NCT01106950.

NK cell CD16 surface expression and function is regulated by a disintegrin and metalloprotease-17 (ADAM17)

The Fc receptor CD16 is present on essentially all CD56(dim) peripheral blood natural killer (NK) cells. Upon recognition of antibody-coated cells it delivers a potent signal to NK cells, which eliminate targets through direct killing and cytokine production. Here we investigated the regulation of CD16 surface expression after NK cell activation. Cytokine activation and target cell stimulation led to marked decreases in CD16 expression. Activation of CD56(dim) NK cells by cross-linking CD16 with antibodies resulted in a loss of CD16 and CD62L, which correlated with increased interferon-γ production. A disintegrin and metalloprotease-17 (ADAM17) is shown to be expressed by NK cells, and its selective inhibition abrogated CD16 and CD62L shedding, and led to enhanced interferon-γ production, especially when triggering was delivered through CD16. Fc-induced production of cytokines by NK cells exposed to rituximab-coated B cell targets was also enhanced by ADAM17 inhibition. This supports an important role for targeting ADAM17 to prevent CD16 shedding and improve the efficacy of therapeutic antibodies. Our findings demonstrate that over-activation of ADAM17 in NK cells may be detrimental to their effector functions by down-regulating surface expression of CD16 and CD62L.

Tim-3 is an inducible human natural killer cell receptor that enhances interferon gamma production in response to galectin-9

NK-cell function is regulated by the integration of signals received from activating and inhibitory receptors. Here we show that a novel immune receptor, T-cell Ig and mucin-containing domain-3 (Tim-3), is expressed on resting human NK cells and is up-regulated on activation. The NK92 NK-cell line engineered to overexpress Tim-3 showed a marked increase in IFN-γ production in the presence of soluble rhGal-9 or Raji tumor cells engineered to express Gal-9. The Tim-3(+) population of low-dose IL-12/IL-18-activated primary NK cells significantly increased IFN-γ production in response to soluble rhGal-9, Gal-9 presented by cell lines, and primary acute myelogenous leukemia (AML) targets that endogenously express Gal-9. This effect is highly specific as Tim-3 Ab blockade significantly decreased IFN-γ production, and Tim-3 cross-linking induced ERK activation and degradation of IκBα. Exposure to Gal-9-expressing target cells had little effect on CD107a degranulation. Reconstituted NK cells obtained from patients after hematopoietic cell transplantation had diminished expression of Tim-3 compared with paired donors. This observation correlates with the known IFN-γ defect seen early posttransplantation. In conclusion, we show that Tim-3 functions as a human NK-cell coreceptor to enhance IFN-γ production, which has important implications for control of infectious disease and cancer.

Human embryonic stem cells differentiate into a homogeneous population of natural killer cells with potent in vivo antitumor activity

Natural killer (NK) cells serve as important effectors for antitumor immunity, and CD56+CD45+ NK cells can be routinely derived from human embryonic stem cells (hESCs). However, little is know about the ability of hESC-derived NK cells to mediate an effective in vivo antitumor response. Using bioluminescent imaging, we now demonstrate that H9 line hESC-derived NK cells mediate effective clearance of human tumor cells in vivo. In addition to increased in vitro killing of diverse tumor targets, the in vivo tumor clearance by H9 hESC-derived NK cells was more effective compared with NK cells derived from umbilical cord blood (UCB). Phenotypic analysis demonstrates the hESC-derived NK cells are uniformly CD94+CD117(low/-), an NK-cell population characterized by potent cytolytic activity and thus more competent to mediate tumor clearance. These studies demonstrate that hESCs provide an important model to study human lymphocyte development and may serve as a novel source for antitumor immunotherapy.

One-Unit versus Two-Unit Cord-Blood Transplantation for Hematologic Cancers

BACKGROUND Umbilical-cord blood has been used as the source of hematopoietic stem cells in an estimated 30,000 transplants. The limited number of hematopoietic cells in a single cord-blood unit prevents its use in recipients with larger body mass and results in delayed hematopoietic recovery and higher mortality. Therefore, we hypothesized that the greater numbers of hematopoietic cells in two units of cord blood would be associated with improved outcomes after transplantation. METHODS Between December 1, 2006, and February 24, 2012, a total of 224 patients 1 to 21 years of age with hematologic cancer were randomly assigned to undergo double-unit (111 patients) or single-unit (113 patients) cord-blood transplantation after a uniform myeloablative conditioning regimen and immunoprophylaxis for graft-versus-host disease (GVHD). The primary end point was 1-year overall survival. RESULTS Treatment groups were matched for age, sex, self-reported race (white vs. nonwhite), performance status, degree of donor-recipient HLA matching, and disease type and status at transplantation. The 1-year overall survival rate was 65% (95% confidence interval [CI], 56 to 74) and 73% (95% CI, 63 to 80) among recipients of double and single cord-blood units, respectively (P=0.17). Similar outcomes in the two groups were also observed with respect to the rates of disease-free survival, neutrophil recovery, transplantation-related death, relapse, infections, immunologic reconstitution, and grade II-IV acute GVHD. However, improved platelet recovery and lower incidences of grade III and IV acute and extensive chronic GVHD were observed among recipients of a single cord-blood unit. CONCLUSIONS We found that among children and adolescents with hematologic cancer, survival rates were similar after single-unit and double-unit cord-blood transplantation; however, a single-unit cord-blood transplant was associated with better platelet recovery and a lower risk of GVHD. (Funded by the National Heart, Lung, and Blood Institute and the National Cancer Institute; ClinicalTrials.gov number, NCT00412360.).