The Analysis of CD83 Expression on Human Immune Cells Identifies a Unique CD83+-Activated T Cell Population.

CD83 is a member of the Ig gene superfamily, first identified in activated lymphocytes. Since then, CD83 has become an important marker for defining activated human dendritic cells (DC). Several potential CD83 mRNA isoforms have been described, including a soluble form detected in human serum, which may have an immunosuppressive function. To further understand the biology of CD83, we examined its expression in different human immune cell types before and after activation using a panel of mouse and human anti-human CD83 mAb. The mouse anti-human CD83 mAbs, HB15a and HB15e, and the human anti-human CD83 mAb, 3C12C, were selected to examine cytoplasmic and surface CD83 expression, based on their different binding characteristics. Glycosylation of CD83, the CD83 mRNA isoforms, and soluble CD83 released differed among blood DC, monocytes, and monocyte-derived DC, and other immune cell types. A small T cell population expressing surface CD83 was identified upon T cell stimulation and during allogeneic MLR. This subpopulation appeared specifically during viral Ag challenge. We did not observe human CD83 on unstimulated human natural regulatory T cells (Treg), in contrast to reports describing expression of CD83 on mouse Treg. CD83 expression was increased on CD4+, CD8+ T, and Treg cells in association with clinical acute graft-versus-host disease in allogeneic hematopoietic cell transplant recipients. The differential expression and function of CD83 on human immune cells reveal potential new roles for this molecule as a target of therapeutic manipulation in transplantation, inflammation, and autoimmune diseases.

Single-Agent High-Dose Cyclophosphamide for Graft-versus-Host Disease Prophylaxis in Human Leukocyte Antigen-Matched Reduced-Intensity Peripheral Blood Stem Cell Transplantation Results in an Unacceptably High Rate of Severe Acute Graft-versus-Host Disease.

High-dose cyclophosphamide given early after allogeneic hemopoietic cell transplantation has been shown to be effective prophylaxis against graft-versus-host disease (GVHD) in the setting of HLA-matched myeloablative bone marrow grafts, allowing avoidance of long-term immunosuppression with calcineurin inhibitors in some patients. Whether this approach is feasible using granulocyte colony-stimulating factor (G-CSF)-mobilized peripheral blood stem cell grafts is unknown. We conducted an exploratory phase 2 trial of cyclophosphamide given at 50 mg/kg i.v. on days 3 and 4 after transplantation as sole GVHD prophylaxis in recipients of G-CSF-mobilized peripheral blood stem cell grafts from HLA-matched related or unrelated donors after reduced-intensity conditioning therapy with fludarabine, carmustine, and melphalan. Five patients, ages 52 to 67 years, with high-risk hematologic malignancies were enrolled. Four of the 5 developed severe acute GVHD of grades 3 to 4, requiring treatment with methylprednisolone and cyclosporine; 3 were steroid refractory and were given salvage therapy. One of these 4 patients died of hepatic GVHD, one died of sepsis, and 2 survived. We conclude that post-transplantation cyclophosphamide is inadequate as sole GVHD prophylaxis in the context of peripheral blood reduced-intensity conditioning transplantations from HLA-matched donors. This trial is registered at ACTRN12613001154796.

A randomized trial of prophylactic palifermin on gastrointestinal toxicity after intensive induction therapy for acute myeloid leukaemia.

Gastrointestinal toxicity, including oral mucositis, is a frequent complication of intensive combination chemotherapy for acute myeloid leukaemia (AML) and contributes substantially to treatment-related mortality. We conducted a placebo-controlled randomized trial to evaluate the efficacy of palifermin (keratinocyte growth factor), given at 60 µg/kg per daily IV for 3 d before and after chemotherapy, for mucosal protection in adult patients with previously untreated AML receiving induction therapy with idarubicin, high-dose cytarabine and etoposide. Among 155 randomized patients, there was no statistically significant difference in the rate of grade 3 and 4 oral mucositis (primary study endpoint) between the two treatment arms (three in palifermin arm (4%), 8 in placebo arm (10%; P = 0·21); however, when considering the severity of oral mucositis (World Health Organization grade 0-4), there was evidence of reduced rates of higher grades of oral mucositis in the palifermin arm (P = 0·0007, test for trend). There was a statistically significantly lower rate of grades 3 and 4 gastrointestinal adverse events in the palifermin arm (21% vs. 44% in placebo arm; P = 0·003), mainly due to a reduction in severe diarrhoea (8% palifermin, 26% placebo; P = 0·01). Palifermin has activity as a mucosal protectant in AML patients receiving intensive chemotherapy. This trial is registered at ACTRN012605000095662.

Sphingosine-1-phosphate facilitates trafficking of hematopoietic stem cells and their mobilization by CXCR4 antagonists in mice.

CXCL12 and VCAM1 retain hematopoietic stem cells (HSCs) in the BM, but the factors mediating HSC egress from the BM to the blood are not known. The sphingosine-1-phosphate receptor 1 (S1P(1)) is expressed on HSCs, and S1P facilitates the egress of committed hematopoietic progenitors from the BM into the blood. In the present study, we show that both the S1P gradient between the BM and the blood and the expression of S1P(1) are essential for optimal HSC mobilization by CXCR4 antagonists, including AMD3100, and for the trafficking of HSCs during steady-state hematopoiesis. We also demonstrate that the S1P(1) agonist SEW2871 increases AMD3100-induced HSC and progenitor cell mobilization. These results suggest that the combination of a CXCR4 antagonist and a S1P(1) agonist may prove to be sufficient for mobilizing HSCs in normal donors for transplantation purposes, potentially providing a single mobilization procedure and eliminating the need to expose normal donors to G-CSF with its associated side effects.

Oncogenic properties of sphingosine kinases in haematological malignancies.

The sphingosine kinases (SphKs) have relatively recently been implicated in contributing to malignant cellular processes with particular interest in the oncogenic properties of SPHK1. Whilst SPHK1 has received considerable attention as a putative oncoprotein, SPHK2 has been much more difficult to study, with often conflicting data surrounding its role in cancer. Initial studies focused on non-haemopoietic malignancies, however a growing body of literature on the role of sphingolipid metabolism in haemopoietic malignancies is now emerging. This review provides an overview of the current state of knowledge of the SphKs and the bioactive lipid sphingosine 1-phosphate (S1P), the product of the reaction they catalyse. It then reviews the current literature regarding the roles of S1P and the SphKs in haemopoietic malignancies and discusses the compounds currently available that modulate sphingolipid metabolism and their potential and shortcomings as therapeutic agents for the treatment of haematological malignancies.

Allogeneic hematopoietic cell transplantation for chronic myelofibrosis in Australia and New Zealand: older recipients receiving myeloablative conditioning at increased mortality risk.

This retrospective registry analysis examined predictive factors for outcome in 57 patients who underwent allogeneic or syngeneic hematopoietic cell transplantation (HCT) for chronic myelofibrosis (CM), either primary (n = 49) or following an antecedent condition (n = 8), reported to the Australasian Bone Marrow Transplant Registry (ABMTRR) between 1993 and 2005. During the 6 years 2000 to 2005, 40 HCTs were performed for CM compared with 17 in the 7 years 1993 to 1999. Twenty-four recipients (42%) were age 50 or over at transplantation; all of these patients were transplanted after 1997, and 15 were given reduced intensity conditioning (RIC) pretransplantation. The cumulative incidence of transplantation-related mortality was 18% at 100 days and 25% at 1 year posttransplantation. Up to 1 year posttransplantation 16 patients died, with the most common causes being infection (n = 6) and graft-versus-host disease (GVHD) (n = 5). A total of 27 patients survived for 3 years or longer posttransplantation. None of these patients required regular red blood cell transfusions, and of the 17 who had not had splenectomies, none had detectable splenomegaly. Twelve patients had no detectable bone marrow fibrosis, 7 had grade 1 fibrosis, and in 8 patients no information was available. The overall survival (OS) probability for all patients was 72% at 1 year and 58% at 5 years posttransplantation. Patients age 50 and over who received myeloablative conditioning fared poorly, with 1-year overall actuarial survival of 44% compared with 77% for all other patients (P = .007). In multivariate analysis, age 50 years and over at transplantation was the only significant independent unfavorable risk factor for survival post-HCT (hazard ratio 2.71, 95% confidence interval 1.16-6.34, P = .02). This study shows a clear increase in annual numbers of allogeneic HCT performed for CM in Australia and New Zealand in recent years. Five-year survival was favorable compared with international studies, but for older recipients who received myeloablative conditioning, mortality risk was elevated.

Potentiating effects of RAD001 (Everolimus) on vincristine therapy in childhood acute lymphoblastic leukemia.

Despite advances in the treatment of acute lymphoblastic leukemia (ALL), the majority of children who relapse still die of ALL. Therefore, the development of more potent but less toxic drugs for the treatment of ALL is imperative. We investigated the effects of the mammalian target of rapamycin inhibitor, RAD001 (Everolimus), in a nonobese diabetic/severe combined immunodeficiency model of human childhood B-cell progenitor ALL. RAD001 treatment of established disease increased the median survival of mice from 21.3 days to 42.3 days (P < .02). RAD001 together with vincristine significantly increased survival compared with either treatment alone (P < .02). RAD001 induced a cell-cycle arrest in the G(0/1) phase with associated dephosphorylation of the retinoblastoma protein, and reduced levels of cyclin-dependent kinases 4 and 6. Ultrastructure analysis demonstrated the presence of autophagy and limited apoptosis in cells of RAD001-treated animals. In contrast, cleaved poly(ADP-ribose) polymerase suggested apoptosis in cells from animals treated with vincristine or the combination of RAD001 and vincristine, but not in those receiving RAD001 alone. In conclusion, we have demonstrated activity of RAD001 in an in vivo leukemia model supporting further clinical development of target of rapamycin inhibitors for the treatment of patients with ALL.

The mammalian target of rapamycin inhibitor RAD001 (everolimus) synergizes with chemotherapeutic agents, ionizing radiation and proteasome inhibitors in pre-B acute lymphocytic leukemia.

BACKGROUND: Despite incremental improvements in outcomes for patients with acute lymphoblastic leukemia, significant numbers of patients still die from this disease. Mammalian target of rapamycin inhibitors have shown potential in vitro and in vivo as therapeutic agents against a range of tumors including acute lymphoblastic leukemia. DESIGN AND METHODS: Flow cytometry was used to evaluate drug-induced cell death in acute lymphoblastic leukemia cell lines and patients' samples. Human xenografts in immunocompromised mice were used to assess the in vivo effects of selected combinations. Pharmacological inhibitors and lentiviral small interfering ribonucleic acid knock-down of p53 were used to investigate the mechanism of cell killing involved. RESULTS: Synergistic interactions between RAD001 and cytotoxic agents were demonstrated in vitro and in vivo, with increased caspase-dependent killing. RAD001 suppressed p53 and p21 responses, while suppression of p53 did not prevent killing, indicating p53 independence. RAD001 and cytotoxic agents activated the JUN N-terminal kinase pathway and the combination further increased JUN N-terminal kinase activation. JUN N-terminal kinase inhibition reduced synergistic cell killing by cytotoxic agents and RAD001 in pre-B acute lymphoblastic leukemia cell lines and patients' samples. Bortezomib and MG132, which activate the JUN N-terminal kinase pathway, also synergized with RAD001 in killing pre-B acute lymphoblastic leukemia cells. Killing was greater when RAD001 was combined with proteasome inhibitors than with cytotoxic drugs. CONCLUSIONS: These observations suggest that combining mammalian target of rapamycin inhibitors with conventional chemotherapy or selected novel agents has the potential to improve clinical responses in patients with pre-B acute lymphoblastic leukemia.

Prophylactic infusion of cytomegalovirus-specific cytotoxic T lymphocytes stimulated with Ad5f35pp65 gene-modified dendritic cells after allogeneic hemopoietic stem cell transplantation.

Cytomegalovirus (CMV) and its therapy continue to contribute to morbidity and mortality in hemopoietic stem cell transplantation (HSCT). Many studies have demonstrated the feasibility of in vitro generation of CMV-specific T cells for adoptive immunotherapy of CMV. Few clinical trials have been performed showing the safety and efficacy of this approach in vivo. In this study, donor-derived, CMV-specific T cells were generated for 12 adult HSCT patients by stimulation with dendritic cells transduced with an adenoviral vector encoding the CMV-pp65 protein. Patients received a prophylactic infusion of T cells after day 28 after HSCT. There were no infusion related adverse events. CMV DNAemia was detected in 4 patients after infusion but was of low level. No patient required CMV-specific pharmacotherapy. Immune reconstitution to CMV was demonstrated by enzyme linked immunospot assay in all recipients with rapid increases in predominantly CMV-pp65 directed immunity in 5. Rates of graft-versus-host disease, infection, and death were not increased compared with expected. These results add to the growing evidence of the safety and efficacy of immunotherapy of CMV in HSCT, supporting its more widespread use. This study was registered at www.anzctr.org.au as #ACTRN12605000213640.

Mannose-binding lectin status is associated with risk of major infection following myeloablative sibling allogeneic hematopoietic stem cell transplantation.

Mannose-binding lectin (MBL) is a mediator of innate immunity that influences the risk of infection in a range of clinical settings. We previously reported associations between MBL2 genotype and infection in a retrospective study of myeloablative allogeneic hematopoietic stem cell transplantation (allo-HCT). However, other studies have been inconclusive, and the role of MBL in reduced-intensity conditioning (RIC) transplantation is unknown. Here we report a prospective study examining MBL2 genotype, MBL levels, and risk of major infection following HLA-matched sibling myeloablative (n = 83) and RIC (n = 59) HCT. Baseline MBL levels were higher in recipients than donors (P < .001), and recipient MBL levels increased during the peritransplantation period (P = .001), most notably in MBL2 wild-type individuals receiving myeloablative total body irradiation (mTBI). MBL2 coding mutations were associated with major infection in recipients receiving mTBI. The cumulative incidence of major infection in recipient harboring an MBL2 mutation receiving mTBI was 70.6%, compared with 31.1% of those without mutations not receiving mTBI (P = .01). MBL status was not associated with infection in RIC transplants. These results confirm the association of MBL status with risk of infection in myeloablative, TBI-conditioned transplantation. Studies examining the role of MBL replacement therapy to prevent infection in this setting should be considered.

Relative survival of long-term hematopoietic cell transplant recipients approaches general population rates.

Whether the annual mortality rates of long-term hematopoietic cell transplant (HCT) survivors ever return to that of the general population is unclear. This study sought to determine the annual long-term mortality rates of allogeneic and autologous HCT recipients who had survived 5 years or more disease-free posttransplant and calculate their relative survival rates. Patients were included if they had a first allogeneic or syngeneic HCT for acute leukemia, chronic myelogenous leukemia (CML) or myelodysplastic syndromes (MDS), or autologous HCT for acute myelogenous leukemia (AML) or lymphoma in Australia or New Zealand between 1992 and 2001, recorded on the Australasian Bone Marrow Transplant Recipient Registry (ABMTRR) database, and were known to have survived, disease free, 5 years or more posttransplant. The annual mortality rates of 5-year transplant survivors were compared to standard Australian and New Zealand populations using relative survival. A total of 1461 HCT survivors (688 postallograft, 773 postautograft) were included in this study. The 10-year survival probability for 5-year allograft survivors was slightly higher than that of 5-year autologous survivors (93.4% versus 89.6%, P=.06). The relative survival of both allogeneic and autologous 5-year survivors was never <97% of that of the general population. However, it was statistically significantly lower than expected in the sixth to ninth years posttransplant, with no obvious pattern of either improvement or deterioration from 6 to 10 years posttransplant. This study indicates that annual relative survival rates of long-term survivors of allogeneic HCT performed in Australia and New Zealand for acute lymophoblastic leukemkia (ALL), AML, CML, and MDS are slightly, but significantly lower than population rates in the 6th to 10th years posttransplant. Annual relative survival rates of long-term survivors of autologous HCT performed in Australia and New Zealand for AML and lymphomas are also slightly lower than population rates up to the 10th year posttransplant. Late deaths from transplant and disease-related causes are unusual, but continue to occur for many years post-HCT.

CXCR4 mediates the homing of B cell progenitor acute lymphoblastic leukaemia cells to the bone marrow via activation of p38MAPK.

The mechanisms regulating the migration of leukaemic cells between the blood and bone marrow compartments remain obscure, but are of fundamental importance for the dissemination of the disease. This study investigated the in vivo homing of human B cell progenitor acute lymphoblastic leukaemia (ALL) cells to the femoral bone marrow of non-obese diabetic severe combined immunodeficient (NOD/SCID) mice. It was demonstrated that patient ALL cells use the chemokine axis, chemokine (CXC motif) receptor 4 (CXCR4)/ chemokine (CXC motif) ligand 12 (CXCL12), to home to the femoral marrow. CXCL12-mediated signalling through p38 mitogen-activated protein kinase (MAPK) was required for optimal homing. In contrast, the homing of normal peripheral blood CD34(+) cells and the cytokine-dependent CD34(+) cell line Mo7e was independent of p38MAPK, consistent with the dependence of these cells, as well as normal CD34(+) CD19(+) B cell progenitors, on PI-3K/AKT signalling. Altogether, our data provide clarification of the direct role of CXCL12 in the bone marrow homing of ALL cells and demonstrate unique signalling molecule usage that may have therapeutic implications for this disease.

Activated circulating dendritic cells after hematopoietic stem cell transplantation predict acute graft-versus-host disease.

BACKGROUND: Dendritic cells (DC) are central to the development of acute graft-versus-host disease (GVHD) following allogeneic hematopoietic stem cell transplantation (alloHSCT). We hypothesized that DC activation status determines the severity of GVHD and that activated DC may be detected in the circulation prior to clinical presentation of GVHD. METHODS: Following transplant, blood samples were obtained twice weekly from alloHSCT patients. Myeloid (CD11c+) and plasmacytoid (CD123hi) DC were enumerated by flow cytometry, and activated myeloid DC were identified using the CMRF-44 monoclonal antibody. RESULTS: Of 40 alloHSCT patients, 26 developed acute GVHD. Severity of GVHD was associated with low total blood DC counts (P=0.007) and with low myeloid and plasmacytoid DC numbers (P=0.015 and 0.003). The CMRF-44 antigen was expressed on blood CD11c+ DC in all cases prior to GVHD onset, whereas of the 14 patients without GVHD, seven had no CMRF-44+ CD11c DC. Patients with CMRF-44+ CD11c+ DC in more than 20% of samples were more likely to subsequently develop acute GVHD (P=0.001, odds ratio=37.1), while patients who developed grade 2-4 GVHD had prior higher percentages of CMRF-44+ CD11c+ DC compared to grade 0-1 GVHD patients (P=0.001). CMRF-44 expression on >7.9% CD11c+ DC predicted for subsequent development of GVHD with a sensitivity of 87.5% and specificity of 79.2%. CONCLUSIONS: Activation status, as assessed by CMRF-44 antigen expression, of blood CD11c+ DC is highly associated with acute GVHD and these cells may be targets for therapeutic intervention.

Defective p38 mitogen-activated protein kinase signaling impairs chemotaxic but not proliferative responses to stromal-derived factor-1alpha in acute lymphoblastic leukemia.

The chemokine stromal-derived factor-1alpha (SDF-1alpha) regulates leukemic cell motility and proliferation; however, the importance of these functions in the growth and dissemination of leukemia is unclear. We examined SDF-1alpha-mediated responses of cells from 27 cases of acute lymphoblastic leukemia (ALL). Although cells from the majority of cases showed chemotactic and proliferative responses to SDF-1alpha, a subset of cases did not undergo chemotaxis in response to SDF-1alpha, while still demonstrating dependence on SDF-1alpha for proliferation in stroma-supported cultures. This chemotactic defect was associated with an absence of phosphorylation of p38 mitogen-activated protein kinase (MAPK) induced by SDF-1alpha, and of SDF-1alpha-induced augmentation of beta(1) integrin-mediated adhesion. Signaling through phosphoinositide 3-kinase and MEK was not affected. No correlation was observed between CXCR4 expression and chemotactic function, in vitro migration into bone marrow stromal layers, and engraftment of leukemic cells in nonobese diabetic/severe combined immunodeficient (NOD/SCID) mice. This study suggests that signaling through p38 MAPK is required for ALL cell chemotaxis but not for proliferation, and that the loss of a chemotactic response to SDF-1alpha does not impede engraftment in NOD/SCID mice.

Bone Marrow Graft-Versus-Host Disease in Major Histocompatibility Complex-Matched Murine Reduced-Intensity Allogeneic Hemopoietic Cell Transplantation.

BACKGROUND: Most clinical allogeneic hemopoietic cell transplants (alloHCT) are now performed using reduced-intensity conditioning (RIC) instead of myeloablative conditioning (MAC); however, the biology underlying this treatment remains incompletely understood. METHODS: We investigated a murine model of major histocompatibility complex-matched multiple minor histocompatibility antigen-mismatched alloHCT using bone marrow (BM) cells and splenocytes from B6 (H-2) donor mice transplanted into BALB.B (H-2) recipients after RIC with fludarabine of 100 mg/kg per day for 5 days, cyclophosphamide of 60 mg/kg per day for 2 days, and total body irradiation (TBI). RESULTS: The lowest TBI dose capable of achieving complete donor chimerism in this mouse strain combination was 325 cGy given as a single fraction. Mice that underwent RIC had a reduced incidence and delayed onset of graft-versus-host disease (GVHD) and significantly prolonged survival compared with MAC-transplanted recipients (TBI of 850 cGy plus cyclophosphamide of 60 mg/kg per day for 2 days). Compared with syngeneic controls, RIC mice with GVHD showed evidence of BM suppression, have anemia, reduced BM cellularity, and showed profound reduction in BM B cell lymphopoiesis associated with damage to the endosteal BM niche. This was associated with an increase in BM CD8 effector T cells in RIC mice and elevated blood and BM plasma levels of T helper1 cytokines. Increasing doses of splenocytes resulted in increased incidence of GVHD in RIC mice. CONCLUSIONS: We demonstrate that the BM is a major target organ of GVHD in an informative clinically relevant RIC mouse major histocompatibility complex-matched alloHCT model by a process that seems to be driven by CD8 effector T cells.

Idarubicin Dose Escalation During Consolidation Therapy for Adult Acute Myeloid Leukemia.

Purpose Higher doses of the anthracycline daunorubicin during induction therapy for acute myeloid leukemia (AML) have been shown to improve remission rates and survival. We hypothesized that improvements in outcomes in adult AML may be further achieved by increased anthracycline dose during consolidation therapy. Patients and Methods Patients with AML in complete remission after induction therapy were randomly assigned to receive two cycles of consolidation therapy with cytarabine 100 mg/m2 daily for 5 days, etoposide 75 mg/m2 daily for 5 days, and idarubicin 9 mg/m2 daily for either 2 or 3 days (standard and intensive arms, respectively). The primary end point was leukemia-free survival (LFS). Results Two hundred ninety-three patients 16 to 60 years of age, excluding those with core binding factor AML and acute promyelocytic leukemia, were randomly assigned to treatment groups (146 to the standard arm and 147 to the intensive arm). Both groups were balanced for age, karyotypic risk, and FLT3-internal tandem duplication and NPM1 gene mutations. One hundred twenty patients in the standard arm (82%) and 95 patients in the intensive arm (65%) completed planned consolidation ( P < .001). Durations of severe neutropenia and thrombocytopenia were prolonged in the intensive arm, but there were no differences in serious nonhematological toxicities. With a median follow-up of 5.3 years (range, 0.6 to 9.9 years), there was a statistically significant improvement in LFS in the intensive arm compared with the standard arm (3-year LFS, 47% [95% CI, 40% to 56%] v 35% [95% CI, 28% to 44%]; P = .045). At 5 years, the overall survival rate was 57% in the intensive arm and 47% in the standard arm ( P = .092). There was no evidence of selective benefit of intensive consolidation within the cytogenetic or FLT3-internal tandem duplication and NPM1 gene mutation subgroups. Conclusion An increased cumulative dose of idarubicin during consolidation therapy for adult AML resulted in improved LFS, without increased nonhematologic toxicity.

Cancer cell-associated fibronectin induces release of matrix metalloproteinase-2 from normal fibroblasts.

The bone and bone marrow are the most common sites of metastasis in breast cancer. Matrix metalloproteinases (MMPs), particularly MMP-2, produced by cancer cells or, more typically, induced in the adjacent normal stroma are necessary for the degradation of extracellular matrix essential for cancer metastasis. Here we describe a mechanism by which breast cancer cells can rapidly use MMP-2 produced by bone marrow fibroblasts (BMFs). MMP-2 is stored in an inactive conformation in association with the cell surface or extracellular matrix of BMFs. Cocultures of BMFs and the human breast cancer cell line MDA-MB-231 induce release of MMP-2 into the culture supernatant without up-regulation of MMP-2 synthesis in either cell. MMP-2 is present on the surface of BMFs and is displaced by MDA-MB-231 cells or by fibronectin or fragments of fibronectin containing the fibronectin type II modules. Moreover, when fibronectin is eluted from the surface of MDA-MB-231 cells, they lose the ability to induce the release of MMP-2 from BMFs. These data are consistent with the displacement of inactive MMP-2 bound to normal fibroblasts via its collagen-binding domain by fibronectin type II modules of cancer cell-associated fibronectin. Cancer cells can then use the proteinase to facilitate tissue invasion. Because an identical mechanism can be demonstrated using fibroblasts from different sources, it is likely to be important for the rapid movement of malignant cells into a variety of normal tissues.

Effects of intensive induction and consolidation chemotherapy with idarubicin and high dose cytarabine on minimal residual disease levels in newly diagnosed adult precursor-B acute lymphoblastic leukemia.

An intensive induction regimen, consisting of idarubicin and high dose cytarabine, was assessed in 19 adult patients, median age 44 years, with newly diagnosed precursor-B acute lymphoblastic leukemia (ALL). Patients achieving a complete response (CR) were given an attenuated consolidation course. The primary endpoints were induction death rate and incidence of serious non-hematological toxicity. Grades 3-4 diarrhoea occurred in 47% of patients during induction. Two patients (11%) died during induction therapy, and 2 were withdrawn due to resistant disease or prolonged marrow hypoplasia. Fifteen patients achieved CR (79%), but levels of minimal residual disease (MRD) after induction were comparable with those previously observed using a modified pediatric protocol. Overall survival at 5 years was 36.8% while leukemia-free survival was 44.1%. An intensive AML protocol used in adults with ALL resulted in substantial toxicity and provided similar levels of cytoreduction to conventional ALL protocols, without improving long-term outcomes.

CMRF-56(+) blood dendritic cells loaded with mRNA induce effective antigen-specific cytotoxic T-lymphocyte responses.

There are numerous transcriptional, proteomic and functional differences between monocyte-derived dendritic cells (Mo-DC) and primary blood dendritic cells (BDC). The CMRF-56 monoclonal antibody (mAb) recognizes a cell surface marker, which is upregulated on BDC following overnight culture. Given its unique ability to select a heterogeneous population of BDC, we engineered a human chimeric (h)CMRF-56 IgG4 mAb to isolate primary BDC for potential therapeutic vaccination. The ability to select multiple primary BDC subsets from patients and load them with in vitro transcribed (IVT) mRNA encoding tumor antigen might circumvent the issues limiting the efficacy of Mo-DC. After optimizing and validating the purification of hCMRF-56(+) BDC, we showed that transfection of hCMRF-56(+) BDC with mRNA resulted in efficient mRNA translation and antigen presentation by myeloid BDC subsets, while preserving superior DC functions compared to Mo-DC. Immune selected and transfected hCMRF-56(+) BDC migrated very efficiently in vitro and as effectively as cytokine matured Mo-DC in vivo. Compared to Mo-DC, hCMRF-56(+) BDC transfected with influenza matrix protein M1 displayed superior MHC peptide presentation and generated potent antigen specific CD8(+) T-cell recall responses, while Wilms tumor 1 (WT1) transfected CMRF-56(+) BDC generated effective primary autologous cytotoxic T-cell responses. The ability of the combined DC subsets within hCMRF-56(+) BDC to present mRNA delivered tumor antigens merits phase I evaluation as a reproducible generic platform for the next generation of active DC immune therapies.