Network geometry of evidence from randomised controlled trials addressing donor selection and source of haematopoietic progenitor cells used in allogeneic transplantation: a systematic scoping review.

BACKGROUND AND METHODS: A scoping review of randomised controlled trials (RCTs) addressing source of cells and choice of donor for allogeneic haematopoietic cell transplantation (HCT) was performed to create a network of best evidence that allows us to identify new potential indirect comparisons for the strategic development of future studies that connect to the existing evidence network. RESULTS: A total of 19 eligible RCTs (2589 total patients) were identified. Nine studies (1566 patients) compared clinical outcomes following the use of peripheral blood progenitor cells (PBPCs) with bone marrow (BM) from matched related donors (eight studies) or matched unrelated donors (one study). The remaining studies compared BM or PBPCs with various methods of BM stimulation or manipulation (six studies), compared different methods of surface molecule-based selection and/or depletion of grafts (two studies) or compared the optimal number of units for paediatric cord blood transplantation (two studies). No published RCTs compared different types of donors. The geometry of the evidence network was analysed to identify opportunities for potential novel indirect comparisons and to identify opportunities to expand the network. Few indirect comparisons are currently feasible due to small sample size and heterogeneity in patient diagnoses and demographics between treatment nodes in the network. CONCLUSION: More RCTs that enrol greater numbers of similar patients are needed to leverage the current evidence network concerning donor choice and source of cells used in allogeneic HCT.

Eltrombopag after allogeneic haematopoietic cell transplantation in a case of poor graft function and systematic review of the literature.

BACKGROUND: Late graft failure after allogeneic haematopoietic cell transplantation (HCT) can result from the failed engraftment of long-term engrafting cells. The use of thrombopoietin (TPO) receptor agonists (TRA) has been extensively studied and remains an important component of experimental ex vivo stem cell expansion protocols, but its use in allogeneic transplantation is still evolving. METHODS: We describe the use of eltrombopag, a TRA, to stimulate the rescue of late graft failure in a patient following allogeneic HCT, and we performed a systematic review of published studies describing the use of TRAs following allogeneic transplantation. RESULTS: A total of eight publications were identified from our systematic search and included observational case studies (five studies, total of seven patients) that primarily addressed ITP or isolated thrombocytopenia at various time points after allogeneic HCT and prospective clinical trials (three studies, total of 177 patients with 95 patients receiving TRAs). No studies reported specifically on the use of TRAs for the treatment of trilineage graft failure as a means of in vivo stem cell expansion. The use of TRAs following allogeneic HCT appears safe and promising. CONCLUSION: The use of eltrombopag or other TRAs to treat poor graft function after allogeneic HCT is intriguing and warrants further study.

A pilot prospective study of the vascular repair response following red cell transfusion in critically ill patients.

BACKGROUND: Red blood cell transfusion has been associated with adverse outcomes including infection, delayed recovery and increased mortality in some patient populations. Circulating cells that yield endothelial-like vascular progenitor cell (VPC) clusters are correlated with vascular repair and recovery after ischaemic injury. The impact of red cell transfusion on VPC clusters and vascular repair remains uncertain. STUDY DESIGN: We prospectively enrolled patients admitted to intensive care requiring red cell transfusion and subjects at low likelihood of requiring red cell transfusion. Levels of VPC clusters and plasma levels of angiogenic cytokines were compared. A total of 17 patients were recruited and had blood samples collected at time of enrolment and at 24-48 h, 48-72 h and 1 week following transfusion. RESULTS: We could not discern differences in the number of VPC clusters between transfused patients (n = 6) and non-transfused subjects (n = 11) at baseline or throughout the study period. VPC cluster levels demonstrated wide variance and were highest at 24-h post-enrolment in the entire cohort. Furthermore, levels of all 16 cytokines analysed were not significantly different between transfused and non-transfused patients and we did not observe a correlation between cytokine concentrations and levels of circulating VPC-cluster forming cells in the overall study population. CONCLUSIONS: Our data suggest that assessment of vascular repair responses after red blood cell transfusion in critically ill patients is challenging. Although our study did not allow us to discern an influence of red cell transfusion on VPC cluster levels or angiogenic cytokines, new methods evaluating vascular repair mechanisms may be required.

Tetrameric complexes of human histocompatibility leukocyte antigen (HLA)-G bind to peripheral blood myelomonocytic cells.

The nonclassical MHC class I molecule human histocompatibility leukocyte antigen (HLA)-G is selectively expressed on fetal trophoblast tissue at the maternal-fetal interface in pregnancy. It has long been suggested that HLA-G may inhibit maternal natural killer (NK) cells through interaction with particular NK cell receptors (KIRs). To investigate interactions of HLA-G, we constructed phycoerythrin-labeled tetrameric complexes of HLA-G refolded with a self-peptide. These HLA-G tetramers failed to bind to NK cells and cells transfected with CD94/NKG2 and killer immunoglobulin-like NK receptors. In contrast, HLA-G tetramers did bind to peripheral blood monocytes, staining a CD16(+)CD14(mid) subset with greater intensity. On transfectants, HLA-G tetramers bound to inhibitory immunoglobulin-like transcript (ILT)2 and ILT4 receptors. However, staining in the presence of antibodies reactive with ILT receptors revealed that the interaction of HLA-G tetramers with blood monocytes was largely due to binding to ILT4. These results suggest that the primary role of HLA-G may be the modulation of myelomonocytic cell behavior in pregnancy.

Evaluating dose-limiting toxicities of MDM2 inhibitors in patients with solid organ and hematologic malignancies: A systematic review of the literature.

INTRODUCTION: Mouse double minute 2 protein (MDM2), a negative regulator of the p53 tumour suppressor gene, is frequently amplified in malignancies. MDM2 antagonists have shown efficacy in treating malignancies with MDM2 overexpression and can overcome chemoresistance in acute myeloid leukemia. We systematically evaluated the safety profile of MDM2 inhibitors in the treatment of solid organ and hematologic malignancies. MATERIALS AND METHODS: We searched Medline and EMBASE from January 1947 to November 2018 for prospective clinical studies, in English or French, investigating any MDM2 inhibitor in pediatric or adult cancers, and reporting dose and toxicity outcomes. Primary outcome was dose-limiting toxicity (DLT) and secondary outcome was death. RESULTS: The search yielded 493 non-duplicate citations. Eighteen studies of 10 inhibitors met inclusion criteria (total N = 1005 patients). Two-thirds of included studies did not define DLTs and the reporting of toxicities was highly variable. The most commonly reported DLTs were cytopenias, gastrointestinal toxicity, metabolic disturbances, fatigue and cardiovascular toxicity; there was one death attributed to treatment toxicity. CONCLUSION: MDM2 antagonists have been studied in a variety of malignancies with toxicities similar to other commonly used chemotherapy agents and may represent a safe adjuvant treatment for further study in in acute leukemia.

TAP- and tapasin-dependent HLA-E surface expression correlates with the binding of an MHC class I leader peptide.

BACKGROUND: The human major histocompatibility complex (MHC) class lb molecule HLA-E is transcribed in most tissues but little is known about its localisation within the cell. We have recently shown that HLA-E binds signal-sequence-derived peptides from human MHC class I molecules in vitro. RESULTS: Using a newly characterised antibody recognising HLA-E, we show that HLA-E is expressed at the cell surface. We demonstrate that HLA-E surface expression is correlated with the presence of MHC class I molecules which provide suitable leader sequence peptides capable of binding to HLA-E. Further studies on the interaction of HLA-E with molecules in the endoplasmic reticulum revealed that HLA-E associates with the transporter associated with antigen processing (TAP) and calreticulin, and that HLA-E expression is TAP-dependent and tapasin-dependent. In addition, HLA-E dissociates from TAP upon binding of MHC class I leader sequence peptides. CONCLUSION: These experiments establish that surface expression of HLA-E is regulated by the binding of a restricted pool of peptides from the leader sequence of MHC class I molecules. The correlation between HLA-E and MHC class I surface expression might be relevant to the function of HLA-E. Our results also show that, although these HLA-E binding peptides are derived from signal sequences, they may be released back into the cytosol and subsequently translocated by the TAP complex and loaded onto HLA-E molecules.

Functions of nonclassical MHC and non-MHC-encoded class I molecules.

Fascinating recent discoveries have focused attention on the nonclassical class I molecules. They can exert their function at most levels of the immune response, being part of both innate and adaptive immune systems. They not only have specialized antigen-presentation functions but also play important immunoregulatory roles: HLA-E regulates natural killer cells by interacting with CD94/NKG2 receptors; the MIC (MHC class I chain related) glycoproteins appear crucial to the activation of gammadelta T cells in the gastrointestinal epithelium; HLA-G may play a role in controlling the immune response to the fetus; and CD1 molecules are important in defense against bacterial infections, as well as in the development and regulation of a subset of NKT cells expressing a highly restricted TCR repertoire; however not all nonclassical class I molecules have an immunological function, as demonstrated by HFE which is implicated in iron metabolism.

Hematopoietic capacity of adult human skeletal muscle is negligible.

Using experimental mouse models, hematopoietic potential has been shown to exist within skeletal muscle. In humans, the clinical utility of using muscle-derived hematopoietic progenitors remains uncertain. Here, we evaluate the hematopoietic potential of human skeletal muscle. De novo adult muscle contained markedly reduced levels of hematopoietic colony-forming units (hCFU) and negligible responsiveness to hematopoietic ex vivo culture conditions that augment hematopoietic activity of fetal muscle. Neither fetal nor adult muscle yielded significant engraftment in transplanted immune-deficient mice. Although adult muscle possessed 1.5+/-0.9 hCFU/g, similar hematopoietic activity (2.3+/-0.17 hCFU) could also be demonstrated from as little as 3-10 microl of contaminating peripheral blood. We suggest that the clinical utility of adult skeletal muscle as an alternative source of hematopoietic cells in humans appears limited due to the low yield of blood-forming precursors and their lack of responsiveness to ex vivo expansion.

Maintaining high autopsy rates in a Canadian blood and marrow transplant program: preserving a diagnostic and research tool.

Autopsy series have revealed patterns of injury in graft-versus-host disease and provided insight into infectious and toxic complications following hematopoietic stem cell transplantation (HSCT). Overall autopsy rates have declined significantly in recent decades including specialized services such as neonatal medicine and cardiac care. However, rates of post-mortem exams at HSCT centers have not been specifically documented. We reviewed hospital records between 1992 and 2002 to determine overall autopsy rates at our hospital and within the HSCT program. Although the overall autopsy rate declined steadily from 24% in 1992 to 9% in 2002, rates of post-mortem exams in the HSCT program remained relatively stable at 32% (24-46%). Autopsy rates were not significantly different for recipients of allogeneic vs autologous transplants and no clear difference was observed for the proportion of autopsies requested on weekdays compared with weekends. Autopsies confirmed major clinical diagnoses and/or suspected causes of death in 45 of 61 autopsies (74%) and yielded major or minor disagreements in clinical diagnosis in 10 cases (16%) and seven cases (11%), respectively. The preservation of high rates of autopsy within our HSCT program demonstrates that specialized programs are able to maintain elevated rates of post-mortem examinations despite overall declining rates.

An in vitro model of innate lymphoid cell function and differentiation.

Innate lymphoid cells (ILC) are RAG-independent lymphocytes with important roles in innate immunity, and include group-1 (natural killer (NK) cell, ILC1), group-2 (ILC2), and group-3 (lymphoid tissue inducer (LTi), NCR(+) ILC3) subsets. Group-3 ILC express Rorγt, produce interleukin (IL)-22, and are critically important in the normal function of mucosal tissues. Here, we describe a novel model cell line for the study of ILC function and differentiation. The parental MNK cell line, derived from NKR-P1B(+) fetal thymocytes, shows a capacity to differentiate in γc cytokines. One IL-7-responsive subline, designated MNK-3, expresses Rorγt and produces high levels of IL-22 in response to IL-23 and IL-1ß stimulation. MNK-3 cells display surface markers and transcript expression characteristic of group-3 ILC, including IL-7Rα (CD127), c-kit (CD117), CCR6, Thy1 (CD90), RANK, RANKL, and lymphotoxin (LTα1ß2). Using an in vitro assay of LTi cell activity, MNK-3 cells induce ICAM-1 and VCAM-1 expression on stromal cells in a manner dependent upon LTα1ß2 expression. A second IL-2-responsive subline, MNK-1, expresses several NK cell receptors, perforin and granzymes, and shows some cytotoxic activity. Thus, MNK-1 cells serve as a model of ILC1/NK development and differentiation, whereas MNK-3 cells provide an attractive in vitro system to study the function of ILC3/LTi cells.

The ILT family of leukocyte receptors.

In this short review we examine the recently identified immunoglobulin-like transcript (ILT) family of receptors (also known as LIR and MIR). ILT are expressed by many leukocyte subsets, especially monocytic cells. Expression levels of certain ILT molecules allow definition of blood monocyte and dendritic cell (DC) subsets. Two receptors, ILT2 and ILT4, recognise a broad range of MHC class I molecules and transduce an inhibitory signal. Such recognition may give many cell lineages the potential to recognise and respond to MHC class I down-regulation.

Number of viable CD34(+) cells reinfused predicts engraftment in autologous hematopoietic stem cell transplantation.

Reduced CD34(+) cell viability due to cryopreservation has unknown effects on subsequent hematopoietic engraftment in autologous transplantation. Thirty-six consecutive autologous peripheral stem cell collections were analyzed for absolute viable CD34(+) cell numbers at the time of stem cell collection and prior to re-infusion. Viable CD34(+) cells were enumerated using single platform flow cytometry and the molecular exclusion dye 7-amino actinomycin D. The median number of viable CD34(+) cells was 3.6 x 10(6)/kg at the time of harvest and 2.0 x 10(6)/kg after thawing. When viable CD34(+)cells enumerated after thawing were <2.0, 2.0-5.0, or >5.0 x 10(6)/kg, the median time to platelet engraftment was 17, 12 and 10 days, respectively (P < 0.05 for comparison of the group with <2.0 x 10(6)/kg and the other two groups), and the median time to neutrophil engraftment was 13, 14 and 12 days, respectively (P = NS). A minimum of 2.0 x 10(6) CD34(+) cells/kg was harvested in 33 of 36 patients (92%) but only 19 of 36 (52%) patients met this threshold at the time of reinfusion. The reduced numbers of viable CD34(+) cells measured prior to re-infusion is associated with time to platelet engraftment and may be useful in monitoring stem cell loss during processing and identifying patients at risk of graft failure.

Outpatient supportive care following chemotherapy for acute myeloblastic leukemia.

Treatment of acute myeloid leukemia (AML) involves aggressive myelosuppressive chemotherapy that is generally administered on an inpatient basis. In our centre, AML therapy has been initiated in hospital and followed by early outpatient supportive care according to guidelines established in 1996. We conducted a review of all patients presenting with AML in our centre between January 1996 and July 1998 to evaluate the safety and feasibility of early outpatient supportive care. Nineteen consecutive patients treated with induction chemotherapy were analyzed. Patients were treated with cytosine arabinoside and an anthracycline as aggressive AML induction therapy with the intent for early discharge. Ten patients (53%) were discharged within 10 days of starting induction chemotherapy (median 4.5 days). Reasons for remaining in hospital included sepsis, serious medical complications, and social and geographic factors. Patients discharged early had a median of 1.5 readmissions (range 0-3), but had 30% fewer in-hospital days than inpatients (p = 0.03), and 57% fewer days of in-hospital antibiotic therapy (p = 0.01). There were no significant differences in transfusion requirements or episodes of febrile neutropenia between the two groups. Thirty-one cycles of consolidation therapy were administered to the 18 patients who survived induction. Early discharge from hospital was achieved for 30 cycles (97%). Nine cycles of consolidation chemotherapy were delivered using outpatient intravenous infusion pumps (29%). This study supports the feasibility and safety of early discharge and outpatient supportive care following chemotherapy for AML.

Endogenous murine leukemia virus DNA sequences in murine cell lines: implications for gene therapy safety testing by PCR.

Safety testing for replication-competent retrovirus (RCR) is an important requirement in gene transfer clinical trials using retroviral vectors. A sensitive polymerase chain reaction (PCR) method is one approach to RCR detection. Only in the presence of RCR will the pol-env encoding sequences, necessary for viral replication and packaging, be amplified from proviral DNA in infected indicator cells. To avoid false-positive results in this assay it is crucial that indicator cell lines are free of endogenous retroviral sequences that could also be amplified with pol-env PCR primers. We screened candidate murine indicator cell lines and determined that while Mus dunni is free of detectable pol-env sequences, endogenous retroviral sequences do indeed exist in several cell lines and lead to false-positive results in the PCR assay for RCR. Furthermore, these endogenous retroviral sequences are expressed as RNA transcripts in NIH 3T3 and SC-1 cell lines, as determined by PCR amplification of cDNA but, nevertheless, do not give rise to replication-competent particles. We recognize the potential for murine cell lines to undergo spontaneous rearrangements of endogenous viral sequences in culture and give rise to recombinants containing newly acquired contiguous pol-env sequences. Indicator cell lines should thus be carefully selected and monitored on an ongoing basis when used in safety testing using PCR approaches for the detection of RCR.

Impact of critical care outreach on hematopoietic stem cell transplant recipients: a cohort study.

Serious morbidity and mortality can occur after hematopoietic SCT (HSCT). Critical care outreach (CCO) can provide timely access to intensive care for hospitalized patients in need of urgent stabilization but has not been examined in HSCT. Rapid Assessment of Critical Events (RACE) team was introduced at our centre January 1, 2005. A retrospective cohort study was performed. Patients undergoing HSCT between January 1, 2000 and December 31, 2004 (n=520) formed the 'before' cohort and patients transplanted between January 1, 2005 and December 31, 2007 (n=294) formed the 'after' cohort. Non-relapse mortality at day 100 after transplant was not different in the two cohorts (26 (8.8%) post-RACE vs 53 (10.2%) pre-RACE, P=0.62). The number of failed organs at time of transfer to intensive care unit (ICU) was reduced in the post-RACE cohort (1.9 ± 0.8 vs 2.3 ± 1.0, P=0.04) and the incidence of cardiovascular failure was lower (23.8 vs 43.8%, P=0.04). Other secondary outcomes were not different, including the frequency of ICU admission. RACE may contribute to earlier stabilization during critical illness in patients undergoing HSCT but does not reduce non-relapse mortality. CCO should be studied prospectively in patients undergoing HSCT to better evaluate its role.

Monoclonal B cells detected in autologous PBSC grafts from patients with classical Hodgkin lymphoma: impact on relapse and survival following transplantation.

Autologous peripheral blood stem cell transplantation (PBSCT) for Hodgkin lymphoma (HL) is curative for many patients with relapsed or refractory disease. Relapsing disease, however, remains a major problem. Neoplastic transformation of B-lymphocytes probably underlies the development of classical HL. Whether clonal B cells are critical for disease evolution and response to therapy in HL remains uncertain. We investigated the impact of clonal B cells detected in peripheral blood stem cell (PBSC) collections on the outcome of patients with HL undergoing transplant. Qualitative semi-nested PCR was carried out on genomic DNA from mononuclear cells from PBSCs to determine the presence of clonal immunoglobulin heavy chain (IgH) complementary-determining region 3 (CDR3) gene rearrangements. Clinical factors were assessed for their association with relapse, overall survival (OS) and progression-free survival (PFS). Among 39 patients undergoing PBSCT, 12 grafts (31%) were PCR positive for clonal IgH rearrangements. OS was better in the PCR-negative group (logrank test, P=0.041). The OS at 5 years was 81% in PCR-negative versus 39% in PCR-positive patients; hazard ratio was 3.23 (95% confidence interval: 0.98-10.63). There was a trend towards better PFS (logrank test, P=0.12), estimated as 71% at 5 years in PCR-negative versus 41% in PCR-positive patients. Clonal B-lymphocytes in PBSC collections of patients with HL identify patients at risk of poor outcome. Larger series are needed to confirm our observations. Insight regarding the role of monoclonal B cells may lead to improved therapies.

Total scalp radiation using image-guided IMRT for progressive cutaneous T cell lymphoma.

Modern radiotherapy has advanced dramatically over the past decade and it is now possible to focus radiotherapy with extreme precision. This allows the radiation dose to be targeted to the area(s) of tumour while sparing adjacent normal tissues even in seemingly complicated and difficult parts of the body. The case report presented here will illustrate how it is possible to irradiate the entire scalp for extensive cutaneous T cell lymphoma while minimising radiotherapy to the underlying brain, orbits and other critical structures.

Contaminating tumour cells in autologous PBSC grafts do not influence survival or relapse following transplant for multiple myeloma or B-cell non-Hodgkin's lymphoma.

Relapsed disease remains a major obstacle following autologous haematopoietic SCT (HSCT) for non-Hodgkin's lymphoma (NHL) and multiple myeloma (MM). Studies regarding the importance of detectable tumour cells in PBSC collections have been inconclusive. Patients undergoing autologous HSCT for NHL and MM between 2001 and 2006 were enrolled (n=158). PBSC grafts were assessed for clonal IgH CDR3 gene rearrangements using qualitative semi-nested PCR. In comparison to patients with PCR-positive PBSC grafts, patients negative for detectable disease had no improvement in overall survival (OS) or PFS for MM (P=0.91 and 0.91) or NHL (P=0.82 and 0.85). Further, no significant difference in OS was observed between patients with PCR-positive compared with PCR-negative PBSC grafts with aggressive NHL histology (P=0.74) or indolent disease (P=0.29). Patients with contaminating tumour cells in autologous PBSCs do not have worsened OS or PFS in MM or NHL. Tumour cells detected by sensitive molecular methods in PBSC collections may be distinct from cells contaminating marrow and appear to have limited utility in identifying patients with MM and B-cell NHL who would benefit from purging strategies.