Activating KIR Haplotype Influences Clinical Outcome Following HLA-Matched Sibling Hematopoietic Stem Cell Transplantation.

Natural killer cells are thought to influence the outcome of hematopoietic stem cell transplant (HSCT), impacting on relapse, overall survival, graft versus host disease and the control of infection, in part through the complex interplay between the large and genetically diverse killer immunoglobulin-like receptor (KIR) family and their ligands. This study examined the relationship between KIR gene content and clinical outcomes including the control of opportunistic infections such as cytomegalovirus in the setting of human leucocyte antigen (HLA)-matched sibling HSCT in an Australian cohort. The presence of the KIR B haplotype which contain more activating receptors in the donor, in particular centromeric B haplotype genes (Cen-B), was associated with improved overall survival of patients with acute myeloid leukemia (AML) undergoing sibling HSCT and receiving myeloablative conditioning. Donor Cen-B haplotype was also associated with reduced acute graft versus host disease grades II-IV whereas donor telomeric-B haplotype was associated with decreased incidence of CMV reactivation. In contrast, we were not able to demonstrate a reduced rate of relapse when the donor had KIR Cen-B, however relapse with a donor Cen-A haplotype was a competing risk factor to poor overall survival. Here we show that the presence of donor activating KIR led to improved outcome for the patient, potentially through reduced relapse rates and decreased incidence of acute GvHD translating to improved overall survival. This article is protected by copyright. All rights reserved.

A national study of the unmet needs of support persons of haematological cancer survivors in rural and urban areas of Australia.

PURPOSE: This study aimed to compare support persons of haematological cancer survivors living in rural and urban areas in regard to the type, prevalence and factors associated with reporting unmet needs. METHODS: One thousand and four (792 urban and 193 rural) support persons of adults diagnosed with haematological cancer were recruited from five Australian state population-based cancer registries. Participants completed the Support Person Unmet Needs Survey (SPUNS) that assessed the level of unmet needs experienced over the past month across six domains. RESULTS: Overall, 66% of support persons had at least one 'moderate, high or very high' unmet need and 24% (n = 182) reported having multiple (i.e. 6 or more) 'high/very high' unmet needs in the past month. There were no significant differences between rural and urban support persons in the prevalence of multiple unmet needs or mean total unmet needs scores. There were however significant differences in the types of 'high/very high' unmet needs with support persons living in rural areas more likely to report finance-related unmet needs. Support persons who indicated they had difficulty paying bills had significantly higher odds of reporting multiple 'high/very high' unmet needs. CONCLUSIONS: This is the first large, population-based study to compare the unmet needs of support persons of haematological cancer survivors living in rural and urban areas. Findings confirm previous evidence that supporting a person diagnosed with haematological cancer correlates with a high level of unmet needs and highlight the importance of developing systemic strategies for assisting support persons, especially in regard to making financial assistance and travel subsidies known and readily accessible to those living in rural areas.

Immunosuppressive human anti-CD83 monoclonal antibody depletion of activated dendritic cells in transplantation.

Current immunosuppressive/anti-inflammatory agents target the responding effector arm of the immune response and their nonspecific action increases the risk of infection and malignancy. These effects impact on their use in allogeneic haematopoietic cell transplantation and other forms of transplantation. Interventions that target activated dendritic cells (DCs) have the potential to suppress the induction of undesired immune responses (for example, graft versus host disease (GVHD) or transplant rejection) and to leave protective T-cell immune responses intact (for example, cytomegalovirus (CMV) immunity). We developed a human IgG1 monoclonal antibody (mAb), 3C12, specific for CD83, which is expressed on activated but not resting DC. The 3C12 mAb and an affinity improved version, 3C12C, depleted CD83(+) cells by CD16(+) NK cell-mediated antibody-dependent cellular cytotoxicity, and inhibited allogeneic T-cell proliferation in vitro. A single dose of 3C12C prevented human peripheral blood mononuclear cell-induced acute GVHD in SCID mouse recipients. The mAb 3C12C depleted CMRF-44(+)CD83(bright) activated DC but spared CD83(dim/-) DC in vivo. It reduced human T-cell activation in vivo and maintained the proportion of CD4(+) FoxP3(+) CD25(+) Treg cells and also viral-specific CD8(+) T cells. The anti-CD83 mAb, 3C12C, merits further evaluation as a new immunosuppressive agent in transplantation.

RAD001 (everolimus) induces dose-dependent changes to cell cycle regulation and modifies the cell cycle response to vincristine.

More than 50% of adults and ~20% of children with pre-B acute lymphoblastic leukemia (ALL) relapse following treatment. Dismal outcomes for patients with relapsed or refractory disease mandate novel approaches to therapy. We have previously shown that the combination of the mTOR inhibitor RAD001 (everolimus) and the chemotherapeutic agent vincristine increases the survival of non-obese diabetic/severe combined immuno-deficient (NOD/SCID) mice bearing human ALL xenografts. We have also shown that 16 µM RAD001 synergized with agents that cause DNA damage or microtubule disruption in pre-B ALL cells in vitro. Here, we demonstrate that RAD001 has dose-dependent effects on the cell cycle in ALL cells, with 1.5 µM RAD001 inhibiting pRb, Ki67 and PCNA expression and increasing G0/1 cell cycle arrest, whereas 16 µM RAD001 increases pRb, cyclin D1, Ki67 and PCNA, with no evidence of an accumulation of cells in G0/1. Transition from G2 into mitosis was promoted by 16 µM RAD001 with reduced phosphorylation of cdc2 in cells with 4 N DNA content. However, 16 µM RAD001 preferentially induced cell death in cells undergoing mitosis. When combined with vincristine, 16 µM RAD001 reduced the vincristine-induced accumulation of cells in mitosis, probably as a result of increased death in this population. Although 16 µM RAD001 weakly activated Chk1 and Chk2, it suppressed strong vincristine-induced activation of these cell cycle checkpoint regulators. We conclude that RAD001 enhances chemosensitivity at least in part through suppression of cell cycle checkpoint regulation in response to vincristine and increased progression from G2 into mitosis.

Haploidentical bone marrow transplants for haematological malignancies using non-myeloablative conditioning therapy and post-transplant immunosuppression with cyclophosphamide: results from a single Australian centre.

AIMS: To demonstrate safety and efficacy of haploidentical bone marrow transplantation with non-myeloablative conditioning and high-dose post-transplant cyclophosphamide in adult patients with leukaemia or lymphoma. BACKGROUND: Human leukocyte antigen haploidentical bone marrow transplantation is a treatment option in patients with haematological malignancies who have no available human leukocyte antigen-matched donor but is limited by conditioning regimen toxicity, graft failure, relapse and graft-versus-host disease (GvHD). METHODS: Twelve patients, median age of 51 years, underwent transplantation with T cell replete bone marrow from a haplotype-matched relative. The conditioning regimen consisted of cyclophosphamide, fludarabine and low-dose total body irradiation. Post-transplant immunosuppression consisted of a single dose of cyclophosphamide 50 mg/kg on day 3, followed by oral tacrolimus and mycophenolate mofetil. Outcomes reported are overall survival, engraftment and chimerism, toxicity, and clinical outcome. RESULTS: All patients had neutrophil recovery (median 14.5 days), and 11 of 12 had platelet engraftment (median 17 days). Two patients had autologous reconstitution. Seven of nine assessable patients had complete donor chimerism. Four patients had grades II-III GvHD, and none had grade IV GvHD. Four patients developed limited stage chronic GvHD. Five patients with acute myeloid leukaemia relapsed. Two patients died of nonrelapse causes, both from other malignancies, and five patients remain alive and relapse free. Median overall survival was 324 days (range 88-1163). CONCLUSION: This regimen is feasible and well tolerated in older patients with high-risk leukaemia or lymphoma, with minimal short-term toxicity and low rates of GvHD. The proportion of disease-free survivors indicates a graft-versus-malignancy effect is present in survivors.

A risk score for early cytomegalovirus reactivation after allogeneic stem cell transplantation identifies low-, intermediate-, and high-risk groups: reactivation risk is increased by graft-versus-host disease only in the intermediate-risk group.

BACKGROUND: This retrospective study was aimed at establishing a clinical score to stratify the risk of cytomegalovirus (CMV) reactivation in patients undergoing allogeneic hematopoietic stem cell transplantation (HSCT) in order to direct strategies for post-transplant CMV monitoring and therapy. PATIENTS AND METHODS: In total, 335 adult patients undergoing HSCT were analyzed and divided into a training set (n = 235) and a validation set (n = 100). Logistic regression analysis on the training set identified recipient and donor CMV seropositivity, acute graft-versus-host disease (GVHD), and use of anti-thymocyte globulin or alemtuzumab as significant risk factors for CMV reactivation. Weighted scores were assigned to each factor. A weighted score (CMV scoring index [CSI]) was calculated for each patient using the scores of all risk factors except for GVHD. The index was collapsed into 3 risk groups - low risk (score of 0-2), intermediate risk (score of 3-5), and high risk (score of 6-7) - and reactivation rates were calculated. In the training set, CMV reactivation occurred in 5.8% in the low-risk group, 44.8% in the intermediate-risk group, and 67.7% in the high-risk group. RESULTS: In patients with an intermediate CSI only, significantly higher reactivation rates were seen in the presence of corticosteroid treatment for GVHD (57.8% vs. 24.5%, P < 0.01). These findings were similar in the validation set with reactivation rates of 0% in the low-risk, 46% in the intermediate-risk, and 68.4% in the high-risk groups. As seen in the training set, the presence of GVHD was associated with higher CMV reactivation rates only in the intermediate-risk group (64% vs. 28% in the absence of GVHD, P = 0.02). CONCLUSIONS: Identification of these 3 risk groups in association with the presence or absence of GVHD will help transplant units to make pre-transplant policy decisions about prophylactic, pre-emptive, or experimental CMV prevention strategies in groups of patients undergoing HSCT, as well as in those developing GVHD post transplant.

Increased activity and improved outcome in unrelated donor haemopoietic cell transplants for acute myeloid leukaemia in Australia, 1992-2005.

BACKGROUND/AIM: Numbers of unrelated donor allogeneic haemopoietic cell transplants (HCT) for acute myeloid leukaemia have increased in Australia in recent years. The aims of this study were to investigate the components of this change and find contributing factors to changes in outcome. METHODS: The study method was a retrospective analysis of 213 consecutive first unrelated donor HCT for acute myeloid leukaemia performed within Australia for adult patients during the years of 1992-1997 (n= 43) and 1998-2005 (n= 170). RESULTS: The proportion of patients transplanted in first or second complete remission (CR) increased markedly from 21% in 1992-1997 to 52% in 1998-2005. The cumulative incidence of relapse at 1 year post HCT was significantly lower for the later cohort (22% vs 30%, P= 0.04) and for patients transplanted in CR compared with those not in CR (16% vs 31%, P= 0.01). The overall survival probability was significantly better at 5 years post HCT for patients transplanted in 1998-2005 compared with 1992-1997 (40% vs 21%, P= 0.04). Multivariate analysis identified five independent significant favourable factors for survival among the whole patient group: age under 40 years, transplant in CR1, CR2 or first relapse, patient CMV seronegativity, good performance status and year of transplant within 1998-2005. CONCLUSION: The later cohort of patients had improved survival even after allowing for the effects of age, remission status and other factors, which suggests a general improvement in the safety of the procedure over time, particularly for patients in early disease stages at transplant.

Pre-transplant cytomegalovirus (CMV) serostatus remains the most important determinant of CMV reactivation after allogeneic hematopoietic stem cell transplantation in the era of surveillance and preemptive therapy.

Between January 2001 and June 2008, 315 adult patients (median age 43 years, range 16-65) including 203 males and 112 females undergoing hematopoietic stem cell transplantation (HSCT) had serial monitoring for cytomegalovirus (CMV) followed by initiation of preemptive therapy. The majority (62.1%) had a conventional myeloablative transplant with 116 (36.9%) having a reduced-intensity conditioning (RIC) transplant, using either matched sibling/family (63.3%) or unrelated donors (36.7%). Graft source was peripheral blood stem cells in 257 (81.5%), bone marrow in 41 (13.1%), and cord blood in 16 (5.4%). T-cell depletion with anti-thymocyte globulin or alemtuzumab was used in 35%. Based upon CMV serostatus, patients were classified into low risk (donor [D]-/recipient [R]-), intermediate risk (D+/R-), or high risk (D-/R+ or D+/R+). Serial weekly monitoring for CMV viremia was performed using a qualitative polymerase chain reaction (PCR) and when positive, quantification was done using either pp65 antigen or a quantitative PCR. CMV reactivation was seen in 123 patients (39.1%) at a median of 50 days post HSCT (range 22-1978). CMV serostatus was the most important risk factor with incidence of 53% in the high-risk group (53.3%) compared with 10.2% in the intermediate risk and 0% in the low-risk group (P<0.0001). Other significant risk factors identified included use of alemtuzumab during conditioning (P=0.03), RIC transplants (P=0.06), and the presence of acute graft-versus-host disease (GVHD) (P<0.0001). On a multivariate analysis, CMV serostatus, RIC transplants, and acute GVHD remained independent predictors of CMV reactivation. All were treated with antiviral therapy with responses seen in 109 (88.6%). Sixteen patients (13%) developed CMV disease at a median of 59 days post HSCT (range 26 days-46 months), 8 of whom died. At a median follow up of 43 months (range 6-93), 166 patients (52.6%) are alive with a significantly higher survival among patients without CMV reactivation (57.2%) as compared with patients with CMV reactivation (45.5%; P=0.049). CMV reactivation and disease remains a major problem in high-risk patients undergoing allogeneic HSCT. Novel prophylactic measures such as immunotherapy and drug prophylaxis need to be considered in this specific group of patients.

Fludarabine-based reduced intensity conditioning transplants have a higher incidence of cytomegalovirus reactivation compared with myeloablative transplants.

Two hundred and ten adult CMV seropositive patients undergoing myeloablative conditioning (MAC) [n=127] or reduced intensity conditioning (RIC) [n=83] transplants (HCT) were serially monitored for CMV reactivation and disease, using a qualitative polymerase chain reaction (PCR) followed by quantitation with pp65 antigen or quantitative PCR. CMV reactivation occurred in 53 RIC (63.9%) and 61 MAC (48%; P=0.03) transplants at a median of 47 days (range: 24-1977). Risk factors identified included acute GVHD (P=0.001), RIC regimen (P=0.03), unrelated donor (P=0.02), use of anti-thymocyte globulin/alemtuzumb (P=0.02) and use of bone marrow in MAC transplants (P=0.011). On multivariate analysis, RIC transplants and acute GVHD remained independent predictors. Treatment with antiviral drugs resulted in CMV negativity rates of 86.8% in MAC and 88.6% in RIC transplants. CMV disease occurred in 10.8% of RIC and 4.7% of MAC transplants (P=0.15). At a median follow-up of 26 months (range: 3-88), 48.1% of RIC and 50.3% of MAC transplants are alive. The higher incidence of CMV reactivation among RIC transplants suggests the need for novel prophylactic or pre-emptive strategies in this high-risk group of patients.

Enrollment of patients to clinical trials in haematological cancer in New South Wales: current status, perceived barriers and opportunities for improvement.

BACKGROUND: Enrolment of cancer patients in clinical trials is associated with significant positive outcomes. There are, however, limited Australian data on enrolment of patients with haematological malignancies to clinical trials. AIM: The aim of this study is to document the number of patients with haematological malignancies enrolled on clinical trials in NSW, to establish the barriers to trial recruitment and to examine possible means by which clinical trials participation may be improved. METHODS: Quantitative data on clinical trial accrual were obtained from all sites participating in clinical trials in haematological malignancies in NSW from 2004 to 2007 and were compared with the cancer incidence data for that period. Qualitative data on barriers and strategies for improvement were gathered using semi-structured interviews with clinical trials professionals from throughout NSW. RESULTS: Between 2004 and 2007 there were significant increases in the number of active centres, clinical trials and trial participation, and by 2007, 10.5% of all eligible patients with haematological malignancies in NSW were enrolled in relevant clinical trials. Resource constraints were the greatest perceived barrier to participation, but the success of clinical trials is also challenged by difficulties associated with communication, ethics review, trial coordination, trial design and support for emerging centres. CONCLUSION: While participation in clinical trials in haematological cancer in NSW improved between 2004 and 2007, participation in clinical trials remains suboptimal. The development of specific strategies to address barriers to participation may facilitate increased enrolment and ultimately improve clinical outcomes in patients with haematological malignancies.

Single versus double unrelated umbilical cord blood units for allogeneic transplantation in adults with advanced haematological malignancies: a retrospective comparison of outcomes.

BACKGROUND: Unrelated umbilical cord blood has emerged as an alternative stem cell source for allogeneic transplantation for patients with haematological malignancies, but in adults is limited by the low number of stem cells present in banked cord blood units. We report our experience with double cord blood transplants for adult patients. The aim of the study was to compare the outcomes of double unrelated cord blood transplants in adults with poor prognosis haematological diseases with single cord blood transplants. METHODS: Eleven patients, median age 27 years and median weight 69 kg, received transplants of two partially matched unrelated cord blood units after myeloablative conditioning therapy. RESULTS: Neutrophil recovery to 0.5 x 10(9)/L was seen by median day 32 (18-53), and platelet recovery to 50 x 10(9)/L by day 91 (56-381). These results were not significantly different from those reported in patients receiving single cord blood transplants. Acute graft-versus-host disease of grades II-IV was seen in four patients, but no chronic graft-versus-host disease occurred. Transplant-related complications were responsible for the deaths of five patients in the first 3 months post-transplant, whereas two patients died of relapse of their haematological malignancy. Four patients survive, disease free, 17-33 months post-transplant. CONCLUSION: Transplantation using two partially matched unrelated cord blood units did not appear to result in improvements either in engraftment or survival, as compared with a previous cohort of patients receiving single cord blood units. Further strategies appear to be needed to reduce the duration of severe neutropenia and reduce the high transplant-related mortality in these patients.

Failure to achieve a threshold dose of CD34+ CD110+ progenitor cells in the graft predicts delayed platelet engraftment after autologous stem cell transplantation.

In this study, we retrospectively analysed the utility of CD110 expression on CD34(+) cells as a predictor of delayed platelet transfusion independence in 39 patients who underwent autologous peripheral blood stem cell transplantation. Absolute CD34(+) cells and CD34(+) subsets expressing CD110 were enumerated using flow cytometry. Of the 39 patients, 7 required 21 days or more to achieve platelet transfusion independence. Six of the seven patients received a dose of CD34(+)CD110(+) cells below 6.0 x 10(4)/kg while 30 of 32 patients who achieved platelet transfusion independence in <21 days received a dose of CD34(+)CD110(+) cells >6.0 x 10(4)/kg (P<0.001). Patients with delayed platelet engraftment received a median dose of 5.2 x 10(4) CD34(+)CD110(+) cells/kg compared with a median dose of 16.4 x 10(4) cells/kg for those engrafting within 21 days (P=0.003). Further analysis showed that >6.0 x 10(4) CD34(+)CD110(+) cells/kg was highly sensitive (93.8%) and highly specific (85.7%) for achieving platelet transfusion independence within 21 days. Delay in platelet transfusion independence translated into an increased requirement for platelet transfusion (median 6 vs 2 transfusions, P<0.0001). The dose of CD34(+)/CD110(+) cells/kg infused at time of transplantation appears to be an important factor identifying patients at risk of delayed platelet engraftment.

Outcome of treatment after first relapse in adults with acute lymphoblastic leukemia initially treated by the LALA-94 trial.

Fifty-four percent of adults with acute lymphoblastic leukemia (ALL) who entered the LALA-94 trial experienced a first relapse. We examined the outcome of these 421 adult patients. One hundred and eighty-seven patients (44%) achieved a second complete remission (CR). The median disease-free survival (DFS) was 5.2 months with a 5-year DFS at 12%. Factors predicting a better outcome after relapse were any transplant performed in second CR (P<0.0001), a first CR duration >1 year (P=0.04) and platelet level >100 x 10(9)/l at relapse (P=0.04). Risk groups defined at diagnosis and treatment received in first CR did not influence the outcome after relapse. The best results were obtained in a subset of patients who were eligible for allogeneic stem cell transplantation (SCT). Geno-identical allogeneic SCT was performed in 55 patients, and 3 patients received donor lymphocyte infusions. Forty-four transplantations were performed from an unrelated donor (of which four were cord blood). We conclude that most adult patients with recurring ALL could not be rescued using current available therapies, although allogeneic SCT remains the best therapeutic option.

The role of high-dose therapy and stem cell rescue in the management of T-cell malignant lymphomas: a BSBMT and ABMTRR study.

Peripheral T-cell lymphomas (PTCL) are a rare and heterogeneous subset of lymphomas with a poorer prognosis compared with B-cell lymphomas. We conducted a retrospective study of 82 patients who received high-dose therapy for PTCL (autologous SCT (ASCT) N=64; allogeneic SCT (Allo-SCT) N=18). With a median follow-up from ASCT of 37 months from transplant, 33 patients were alive; 20 died of progressive disease, 10 died from non-relapse mortality (NRM) with 1 unknown cause. Three-year overall survival (OS) and progression-free survival (PFS) were 53% (95% confidence interval (CI) 42, 67) and 50% (95% CI 39, 64), respectively. Factors significantly affecting OS and PFS on univariate analysis were histological subtype and chemotherapy sensitivity. In a multivariate analysis, the only factor with significant impact was chemotherapy sensitivity. After a median follow-up from Allo-SCT of 57 months, five patients were alive; five died of progressive disease and eight died from NRM. The 3-year OS and PFS were 39% (95% CI 22, 69) and 33% (95% CI 17, 64), respectively, and the 3-year relapse rate was 28% (95% CI 6, 50). These results demonstrate that high-dose chemotherapy with autologous stem cell rescue has a substantial role in the management of T-cell lymphoma. The use of full-intensity allogeneic transplantation is limited by high transplant-related mortality, and exploration of reduced intensity regimens is warranted.

A prospective multicenter trial of peripheral blood stem cell sibling allografts for acute myeloid leukemia in first complete remission using fludarabine-cyclophosphamide reduced intensity conditioning.

The role of allogeneic transplantation in patients with de novo acute myeloid leukemia in first complete remission (AML-CR1) is controversial. Aiming to preserve a graft-versus-leukemia effect, but minimize morbidity and mortality from conditioning-related toxicity and graft-versus-host disease (GVHD), we conducted a prospective multicenter study of reduced-intensity conditioning (RIC) as preparation for peripheral blood stem cell sibling allografts in patients with intermediate or poor risk AML-CR1. Conditioning consisted of fludarabine 125 mg/m(2) and cyclophosphamide 120 mg/kg. Thirty-four patients were transplanted with a median age of 45 years; 85% had intermediate risk cytogenetics. Early toxicity was minimal. The overall incidence of grade II-IV acute GVHD was low (21%), but the 3 patients (9%) who developed grade IV GVHD died. Donor T cell chimerism was rapid and generally complete, but complete myeloid chimerism was delayed. Thirteen patients (38%) relapsed, 12 within a year of transplant. The estimated disease-free survival (DFS) and overall survival at 2 years was 56% (95% confidence interval [CI] 39%-71%) and 68% (95% CI 50%-81%), respectively. The incidence of extensive chronic GVHD (cGVHD) was low (24% of surviving patients at 12 months) and most survivors had an excellent performance status. These observations justify a prospective comparison of RIC versus myeloablative conditioning allografts for AML-CR1.

Rapid expansion of tumor-reactive cells from HLA-matched siblings for adoptive immunotherapy of melanoma.

BACKGROUND: Administration of expanded tumor-infiltrating lymphocytes in association with lymphodepleting chemotherapy is effective in some patients with advanced malignant melanoma. However, obtaining lymphocytes and subsequent expansion is labor intensive, making it impractical for broad clinical application. Allogeneic transplantation may have anti-melanoma efficacy because of a graft vs. tumor effect. The disappointing tumor control observed post-transplant suggests that adoptive immunotherapy using melanoma-reactive cells will be essential for sustained responses. METHODS: Melanoma cell lines were grown from two patients with advanced disease. High-level CD80 and CD86 expression was obtained in the tumor lines using a retroviral vector for gene transfer. Transduced melanoma and controls were cultured with mononuclear cells from HLA-identical sibling donors. RESULTS: Expression of CD80 and CD86, particularly the former, promoted marked expansion of lymphocytes from HLA-matched sibling donors. Proliferation of up to 300-fold after 4 weeks of culture was observed. Lymphocytes from cultures stimulated with CD80 demonstrated cytotoxicity against recipient-untransfected melanoma (45-75% specific lysis at an E:T ratio of 50:1). Although expanded lymphocytes were predominantly CD4(+), cytotoxicity was greatest in the numerically smaller CD8(+) subpopulation. Both CD4(+) and CD8(+) cells secreted IFN-gamma (but not IL-4) on exposure to untransduced stimulator melanoma cells. DISCUSSION: Our strategy generates a large number of melanoma-reactive lymphocytes from HLA-identical siblings using a 4-week culture strategy. Lymphocytes expanded in this way offer an alternative to tumor-infiltrating lymphocytes for allogeneic cellular immunotherapy after stem cell transplantation in young patients.

CXCR4 antagonists mobilize childhood acute lymphoblastic leukemia cells into the peripheral blood and inhibit engraftment.

The role of CXCL12 in the bone marrow (BM) homing and growth of B-cell progenitor acute lymphoblastic leukemia (ALL) has been established. However, the effect of modulating CXCL12/CXCR4 interactions on the retention of ALL cells within the supportive BM microenvironment and the expansion and dissemination of ALL cells in vivo has not been examined. We used mouse models of human childhood and murine leukemia and specific peptide and small molecule CXCR4 antagonists to examine the importance of CXCL12/CXCR4 in the development of leukemia in vivo. CXCR4 antagonists mobilized ALL cells into the peripheral blood (PB). Extended administration of CXCR4 antagonists to mice with leukemia resulted in a reduction in the number of leukemic cells in the PB and spleens of animals compared to control treated animals in three of the five cases tested. There was also a marked reduction in the dissemination of ALL cells to extramedullary sites including liver and kidney in all cases where this occurred. Considering the inhibitory effect of stromal layers on the activity of chemotherapeutic agents and the interactive effect of CXCL12 antagonists with chemotherapeutic agents in vitro, this raises the possibility of using these agents to potentiate the effects of current chemotherapy regimens.