A comparative study of reduced dose alemtuzumab in matched unrelated donor and related donor reduced intensity transplants.

In vivo T cell depletion with 100 mg alemtuzumab prevents graft-versus-host disease (GVHD) in reduced intensity conditioned transplants but is associated with delayed immune reconstitution, a higher risk of infection and relapse. De-escalation studies have shown that a reduced dose of 30 mg is as effective as 100 mg in preventing GVHD in matched related donor (MRD) transplants. Dose reduction in matched unrelated donor (MUD) transplants is feasible but the comparative efficacy of alemtuzumab in this setting is not known and opinions vary widely concerning the optimal level of GVHD prophylaxis that should be achieved. Through retrospective analysis we made an objective comparison of MUD transplants receiving an empirically reduced dose of 60 mg, with MRD transplants receiving a 30 mg dose. We observed proportionate levels of alemtuzumab according to dose but an inverse relationship with body surface area particularly in MRD transplants. MUD transplants experienced more acute and chronic GVHD, higher T cell chimerism, more sustained use of ciclosporin and less need for donor lymphocyte infusion than MRD transplants. Thus, doubling the dose of alemtuzumab to 60 mg did not provide equivalent prevention of GVHD after MUD transplant although there was no difference in non-relapse mortality or survival compared with MRD transplants.

Use of a biosimilar granulocyte colony-stimulating factor for peripheral blood stem cell mobilization: an analysis of mobilization and engraftment.

Peripheral blood haematopoietic progenitor cell mobilization has become a standard procedure prior to autologous stem cell transplantation. Biosimilar granulocyte colony-stimulating factors (GCSF) have recently been awarded European Union (EU) licences for stem cell mobilization but data for their use in this context remain limited. The biosimilar GCSF, Ratiograstim(®) (Ratiopharm, Ulm, Germany) was granted an EU licence in September 2008 and incorporated into clinical practice in the Wessex Blood and Marrow Transplantation Programme in December 2008. Data were retrospectively collected for 154 consecutive patients undergoing peripheral blood stem cell harvest between January 2009 and December 2011 using the biosimilar GCSF. 131 consecutive patients from the preceding 3 years, who had received Neupogen(®) , were used as a control. We analysed both parameters relevant to stem cell collection and engraftment data, where patients proceeded to transplantation. We found no statistically significant difference between the two groups when comparing CD34 predictors, total number of CD34(+) stem cells collected, number of days required for collection, or for time to engraftment. This is, to our knowledge, the largest direct comparison of a biosimilar GCSF with originator GCSF for stem cell mobilization. The use of biosimilar GCSF can produce a significant cost saving, allowing investment in other areas of stem cell transplantation.

Myeloproliferative neoplasms.

The myeloproliferative neoplasms that are associated with the JAK2 mutation are a heterogeneous group of disorders. The additional mutations that result in the clinical phenotype are still the subject of research. As more than one mutation is involved, and as JAK2 has a necessary physiological role (unlike BCR-ABL), the development of targeted therapy remains a challenge. Although new drugs are being developed, treatment at present is predominantly with agents that have been in use for many years. An understanding of the need to control the thrombotic risk has, however, led to improved survival rates such that ET and PV can be seen as chronic diseases.

Donor monocyte-derived macrophages promote human acute graft-versus-host disease.

Myelopoiesis is invariably present and contributes to pathology in animal models of graft-versus-host disease (GVHD). In humans, a rich inflammatory infiltrate bearing macrophage markers has also been described in histological studies. In order to determine the origin, functional properties, and role in pathogenesis of these cells, we isolated single-cell suspensions from acute cutaneous GVHD and subjected them to genotype, transcriptome, and in vitro functional analysis. A donor-derived population of CD11c+CD14+ cells was the dominant population of all leukocytes in GVHD. Surface phenotype and NanoString gene expression profiling indicated the closest steady-state counterpart of these cells to be monocyte-derived macrophages. In GVHD, however, there was upregulation of monocyte antigens SIRPα and S100A8/9 transcripts associated with leukocyte trafficking, pattern recognition, antigen presentation, and costimulation. Isolated GVHD macrophages stimulated greater proliferation and activation of allogeneic T cells and secreted higher levels of inflammatory cytokines than their steady-state counterparts. In HLA-matched mixed leukocyte reactions, we also observed differentiation of activated macrophages with a similar phenotype. These exhibited cytopathicity to a keratinocyte cell line and mediated pathological damage to skin explants independently of T cells. Together, these results define the origin, functional properties, and potential pathogenic roles of human GVHD macrophages.

Serum Flt3 ligand is a biomarker of progenitor cell mass and prognosis in acute myeloid leukemia.

Fms-like tyrosine kinase 3 (Flt3) is expressed on progenitor cells and acute myeloid leukemia (AML) blasts. Fms-like tyrosine kinase 3 ligand (Flt3L) is detectable during homeostasis and increases in hypoplasia due to genetic defects or treatment with cytoreductive agents. Conversely, Flt3+ AML is associated with depletion of Flt3L to undetectable levels. After induction chemotherapy, Flt3L is restored in patients entering complete remission (CR) but remains depressed in those with refractory disease. Weekly sampling reveals marked differences in the kinetics of Flt3L response during the first 6 weeks of treatment, proportionate to the clearance of blasts and cellularity of the bone marrow. In the UK NCRI AML17 trial, Flt3L was measured at day 26 in a subgroup of 140 patients with Flt3 mutation randomized to the tyrosine kinase inhibitor lestaurtinib or placebo. In these patients, attainment of CR was associated with higher Flt3L at day 26 (Mann-Whitney UP < .0001). Day 26 Flt3L was also associated with survival; Flt3L ≤291 pg/mL was associated with inferior event-free survival (EFS), and Flt3L >1185 pg/mL was associated with higher overall survival (OS; P = .0119). The separation of EFS and OS curves increased when minimal residual disease (MRD) status was combined with Flt3L measurement, and Flt3L retained a near-significant association with survival after adjusting for MRD in a proportional hazards model. Serial measurement of Flt3L in patients who had received a hematopoietic stem cell transplant for AML illustrates the potential value of monitoring Flt3L to identify relapse. Measurement of Flt3L is a noninvasive test with the potential to inform clinical decisions in patients with AML.

Application of the pMHC Array to Characterise Tumour Antigen Specific T Cell Populations in Leukaemia Patients at Disease Diagnosis.

Immunotherapy treatments for cancer are becoming increasingly successful, however to further improve our understanding of the T-cell recognition involved in effective responses and to encourage moves towards the development of personalised treatments for leukaemia immunotherapy, precise antigenic targets in individual patients have been identified. Cellular arrays using peptide-MHC (pMHC) tetramers allow the simultaneous detection of different antigen specific T-cell populations naturally circulating in patients and normal donors. We have developed the pMHC array to detect CD8+ T-cell populations in leukaemia patients that recognise epitopes within viral antigens (cytomegalovirus (CMV) and influenza (Flu)) and leukaemia antigens (including Per Arnt Sim domain 1 (PASD1), MelanA, Wilms' Tumour (WT1) and tyrosinase). We show that the pMHC array is at least as sensitive as flow cytometry and has the potential to rapidly identify more than 40 specific T-cell populations in a small sample of T-cells (0.8-1.4 x 10(6)). Fourteen of the twenty-six acute myeloid leukaemia (AML) patients analysed had T cells that recognised tumour antigen epitopes, and eight of these recognised PASD1 epitopes. Other tumour epitopes recognised were MelanA (n = 3), tyrosinase (n = 3) and WT1(126-134) (n = 1). One of the seven acute lymphocytic leukaemia (ALL) patients analysed had T cells that recognised the MUC1(950-958) epitope. In the future the pMHC array may be used provide point of care T-cell analyses, predict patient response to conventional therapy and direct personalised immunotherapy for patients.

Biosimilar G-CSF based mobilization of peripheral blood hematopoietic stem cells for autologous and allogeneic stem cell transplantation.

The use of granulocyte colony stimulating factor (G-CSF) biosimilars for peripheral blood hematopoietic stem cell (PBSC) mobilization has stimulated an ongoing debate regarding their efficacy and safety. However, the use of biosimilar G-CSF was approved by the European Medicines Agency (EMA) for all the registered indications of the originator G-CSF (Neupogen (®) ) including mobilization of stem cells. Here, we performed a comprehensive review of published reports on the use of biosimilar G-CSF covering patients with hematological malignancies as well as healthy donors that underwent stem cell mobilization at multiple centers using site-specific non-randomized regimens with a biosimilar G-CSF in the autologous and allogeneic setting. A total of 904 patients mostly with hematological malignancies as well as healthy donors underwent successful autologous or allogeneic stem cell mobilization, respectively, using a biosimilar G-CSF (520 with Ratiograstim®/Tevagrastim, 384 with Zarzio®). The indication for stem cell mobilization in hematology patients included 326 patients with multiple myeloma, 273 with Non-Hodgkin's lymphoma (NHL), 79 with Hodgkin's lymphoma (HL), and other disease. 156 sibling or volunteer unrelated donors were mobilized using biosimilar G-CSF. Mobilization resulted in good mobilization of CD34+ stem cells with side effects similar to originator G-CSF. Post transplantation engraftment did not significantly differ from results previously documented with the originator G-CSF. The side effects experienced by the patients or donors mobilized by biosimilar G-CSF were minimal and were comparable to those of originator G-CSF. In summary, the efficacy of biosimilar G-CSFs in terms of PBSC yield as well as their toxicity profile are equivalent to historical data with the reference G-CSF.