Prevention and management of infections after exposure to ionising radiation.

Ionising radiation impacts many organ systems, each of which comprises a level of immunity to infectious disease. Bone marrow toxicity after radiation results in a predisposition to leukopenia and subsequent susceptibility to bacterial, viral, and fungal infections. Radiation-induced damage to mucosal, integumentary, and solid organ structures disrupts additional lines of innate defense. Over the past three decades, much progress has been made in effective antimicrobial prophylaxis, resulting in decreased infectious complications and improved survival. Vaccination schedules following myeloablative radiation have become highly regimented and treatment of overt infectious complications is largely standardised. In this article, we discuss consequences, prevention, and management of infections following exposure to ionising radiation.

Transient Tertiary Structures of Disordered Dynein Intermediate Chain Regulate its Interactions with Multiple Partners.

The N-terminal domain of dynein intermediate chain (N-IC) is central to the cytoplasmic dynein 'cargo attachment subcomplex' and regulation of motor activity. It is a prototypical intrinsically disordered protein (IDP), serving as a primarily disordered polybivalent molecular scaffold for numerous binding partners, including three dimeric dynein light chains and coiled coil domains of dynein partners dynactin p150Glued and NudE. At the very N-terminus, a 40 amino acid single alpha helix (SAH) forms the major binding site for both p150Glued and NudE, while a shorter nascent helix (H2) separated from SAH by a disordered linker, is necessary for tight binding to dynactin p150Glued but not to NudE. Here we demonstrate that transient tertiary interactions in this highly dynamic protein underlie the differences in its interactions with p150Glued and NudE. NMR paramagnetic relaxation enhancement experiments and restrained molecular dynamics simulations identify interactions between the two non-contiguous SAH and H2 helical regions, the extent of which correlates with the length and stability of H2, showing clearly that tertiary and secondary structure formation are coupled in IDPs. These interactions are significantly attenuated when N-IC is bound to NudE, suggesting that NudE binding shifts the conformational ensemble to one that is more extended and with less structure in H2. While the intrinsic disorder and flexibility in N-IC modulate its ability to serve as a binding platform for numerous partners, deviations of this protein from random-coil behavior provide a process for regulating these binding interactions and potentially the dynein motor.

Allogeneic hematopoietic cell transplantation with non-myeloablative conditioning for patients with hematologic malignancies: Improved outcomes over two decades.

We have used a non-myeloablative conditioning regimen for allogeneic hematopoietic cell transplantation for the past twenty years. During that period, changes in clinical practice have been aimed at reducing morbidity and mortality from infections, organ toxicity, and graft-versus-host disease. We hypothesized that improvements in clinical practice led to better transplantation outcomes over time. From 1997-2017, 1,720 patients with hematologic malignancies received low-dose total body irradiation +/- fludarabine or clofarabine before transplantation from HLA-matched sibling or unrelated donors, followed by mycophenolate mofetil and a calcineurin inhibitor ± sirolimus. We compared outcomes in three cohorts by year of transplantation: 1997 +/- 2003 (n=562), 2004 +/- 2009 (n=594), and 2010 +/- 2017 (n=564). The proportion of patients ≥60 years old increased from 27% in 1997 +/- 2003 to 56% in 2010-2017, and with scores from the Hematopoietic Cell Transplantation Comborbidity Index of ≥3 increased from 25% in 1997 +/- 2003 to 45% in 2010 +/- 2017. Use of unrelated donors increased from 34% in 1997 +/- 2003 to 65% in 2010-2017. When outcomes from 2004 +/- 2009 and 2010-2017 were compared to 1997 +/- 2003, improvements were noted in overall survival (P=.0001 for 2004-2009 and P <.0001 for 2010-2017), profression-free survival (P=.002 for 2004-2009 and P <.0001 for 2010 +/- 2017), non-relapse mortality (P<.0001 for 2004 +/- 2009 and P <.0001 for 2010 +/- 2017), and in rates of grades 2 +/- 4 acute and chronic graft-vs.-host disease. For patients with hematologic malignancies who underwent transplantation with non-myeloablative conditioning, outcomes have improved during the past two decades. Trials reported are registered under ClinicalTrials.gov identifiers: NCT00003145, NCT00003196, NCT00003954, NCT00005799, NCT00005801, NCT00005803, NCT00006251, NCT00014235, NCT00027820, NCT00031655, NCT00036738, NCT00045435, NCT00052546, NCT00060424, NCT00075478, NCT00078858, NCT00089011, NCT00104858, NCT00105001, NCT00110058, NCT00397813, NCT00793572, NCT01231412, NCT01252667, NCT01527045.

Health state utilities associated with treatment options for acute myeloid leukemia (AML).

Aims: Acute myeloid leukemia (AML) treatment typically involves remission induction chemotherapy followed by consolidation chemotherapy. New treatments for AML have recently been introduced, including a chemotherapy formulation called CPX-351, which is administered via less time-intensive IV infusion than the standard "7 + 3" continuous infusion regimen of cytarabine plus an anthracycline. The purpose of this study was to estimate utilities that could be used in economic modeling of AML treatment. Materials and methods: In time trade-off interviews, participants from the UK general population valued 12 health states drafted based on literature and clinician interviews. To identify disutility associated with chemotherapy, two types of induction and four types of consolidation were added to an otherwise identical health state describing AML. The decrease in utility when adding these chemotherapy regimens represents the disutility of each regimen. Five additional health states were valued to estimate utilities associated with other AML treatments. Results: Two hundred participants completed interviews. Mean (SD) utilities were 0.55 (0.31) for pre-treatment AML and 0.66 (0.29) for AML in temporary remission. Adding any chemotherapy significantly decreased utility (p < 0.0001). Induction had a mean disutility of -0.11 with CPX-351 and -0.15 with 7 + 3. Mean disutility for consolidation ranged from -0.03 with outpatient CPX-351 to -0.11 with inpatient 5 + 2. Utilities are also reported for other AML treatments (e.g. transplant, low-intensity chemotherapy). Limitations: One limitation is that the differences in adverse event profiles between the treatment regimens were based on clinician opinion. Future use of CPX-351 in clinical trials or clinical settings will provide additional information on its adverse event profile. Conclusions: While all chemotherapy regimens were associated with disutility, regimens with shorter hospitalization and less time-intensive infusion were generally perceived as preferable. These utilities may be useful in cost-utility models comparing the value of AML treatments.

Investigation of Nascent Base Pair and Polymerase Behavior in the Presence of Mismatches in DNA Polymerase I Using Molecular Dynamics.

Optimizing DNA polymerases for a broad range of tasks requires an understanding of the factors influencing polymerase fidelity, but many details of polymerase behavior remain unknown, especially in the presence of mismatched nascent base pairs. Using molecular dynamics, the large fragment of Bacillus stearothermophilus DNA polymerase I is simulated in the presence of all 16 possible standard nucleoside triphosphate-template (dNTP-dN) pairs, including four Watson-Crick pairs and 12 mismatches. The precatalytic steps of nucleotide addition from nucleotide insertion to immediately preceding catalysis are explored using three starting structures representing different stages of nucleotide addition. From these simulations, interactions between dNTPs and the DNA-protein complex formed by the polymerase are elucidated. Patterns of large-scale conformational shifts, classification of nucleotide pairs based on composition, and investigation of the roles of residues interacting with dNTPs are completed on 50+ µs of simulation. The role of molecular dynamics in studies of polymerase behavior is discussed.

Improved Accuracy for Constant pH-REMD Simulations through Modification of Carboxylate Effective Radii.

The accuracy of computational models for simulating biomolecules under specific solution pH conditions is critical for properly representing the effect of pH in biological processes. Constant pH (CpH) simulations involving implicit solvent using the AMBER software often incorrectly estimate pKa values of aspartate and glutamate residues due to large effective radii stemming from the presence of dummy protons. These inaccuracies stem from problems in the sampled ensembles of titratable residues that can influence other observable pH-dependent behavior, such as conformational change. We investigate new radii assignments for atoms in titratable residues with carboxylate groups to mitigate the systematic overestimation in the current method. We find that decreased carboxylate radii correspond with increased agreement with experimentally derived pKa values for residues in hen egg-white lysozyme and Δ+PHS variants of staphylococcal nuclease (SNase) and improved conformation state sampling compared to experimentally described expectations of native-like structure. Our CpH simulations suggest that decreasing the effective radii of these carboxylate groups is essential for eliminating a significant source of systematic error that hurts the accuracy of both conformational and protonation state sampling with implicit solvent.

Cardiovascular Oncologic Emergencies.

Oncologic emergencies can present either as a progression of a known cancer or as the initial presentation of a previously undiagnosed cancer. In most of these situations, a very high degree of suspicion is required to allow prompt assessment, diagnosis, and treatment. In this article, we review the presentation and management of cardiovascular oncologic emergencies from primary and metastatic tumors of the heart and complications such as pericardial tamponade, superior vena cava syndrome, and hyperviscosity syndrome. We have included the cardiovascular complications from radiation therapy, chemotherapeutic agents, and biologic agents used in modern cancer treatment.

Cellular transplant therapies for globoid cell leukodystrophy: Preclinical and clinical observations.

Globoid cell leukodystrophy (GLD) is a progressive neurodegenerative disorder caused by the deficiency of galactocerebrosidase (GALC), resulting in accumulation of toxic metabolites in neural tissues. Clinically variable based on age of onset, infantile GLD is generally a rapidly fatal syndrome of progressive neurologic and cognitive decline, whereas later-onset GLD has a more indolent, protracted clinical course. Animal models, particularly the twitcher mouse, have allowed investigation of both the pathophysiology of and the potential treatment modalities for GLD. Cellular therapy for GLD, notably hematopoietic cell transplantation (HCT; transplantation of bone marrow, peripheral blood stem cells, or umbilical cord blood cells) from a normal related or unrelated allogeneic donor provides a self-renewing source of GALC in donor-derived cells. The only currently available treatment option in human GLD, allogeneic HCT, can slow the progression of the disease and improve survival, especially when performed in presymptomatic infants. Because persistent neurologic dysfunction still occurs after HCT in GLD, preclinical studies are evaluating combinations of HCT with other treatment modalities. © 2016 Wiley Periodicals, Inc.

Polycythaemia: an unusual presentation of multiple myeloma.

In contrast to anaemia, polycythaemia is a distinctly uncommon finding in patients with multiple myeloma. We describe the presence of otherwise unexplained polycythaemia in a 57-year-old Caucasian man who was found to have IgG κ multiple myeloma. After treatment of myeloma, the polycythaemia resolved. We reviewed previous reports of polycythaemia associated with multiple myeloma and discuss potential pathophysiological mechanisms that link these 2 conditions.

Efficacy of Pharmacokinetics-Directed Busulfan, Cyclophosphamide, and Etoposide Conditioning and Autologous Stem Cell Transplantation for Lymphoma: Comparison of a Multicenter Phase II Study and CIBMTR Outcomes.

Busulfan, cyclophosphamide, and etoposide (BuCyE) is a commonly used conditioning regimen for autologous stem cell transplantation (ASCT). This multicenter, phase II study examined the safety and efficacy of BuCyE with individually adjusted busulfan based on preconditioning pharmacokinetics. The study initially enrolled Hodgkin lymphoma (HL) and non-Hodgkin lymphoma (NHL) patients ages 18 to 80 years but was amended due to high early treatment-related mortality (TRM) in patients > 65 years. BuCyE outcomes were compared with contemporaneous recipients of carmustine, etoposide, cytarabine, and melphalan (BEAM) from the Center for International Blood and Marrow Transplant Research. Two hundred seven subjects with HL (n = 66) or NHL (n = 141) were enrolled from 32 centers in North America, and 203 underwent ASCT. Day 100 TRM for all subjects (n = 203), patients > 65 years (n = 17), and patients ≤ 65 years (n = 186) were 4.5%, 23.5%, and 2.7%, respectively. The estimated rates of 2-year progression-free survival (PFS) were 33% for HL and 58%, 77%, and 43% for diffuse large B cell lymphoma (DLBCL; n = 63), mantle cell lymphoma (MCL; n = 29), and follicular lymphoma (FL; n = 23), respectively. The estimated rates of 2-year overall survival (OS) were 76% for HL and 65%, 89%, and 89% for DLBCL, MCL, and FL, respectively. In the matched analysis rates of 2-year TRM were 3.3% for BuCyE and 3.9% for BEAM, and there were no differences in outcomes for NHL. Patients with HL had lower rates of 2-year PFS with BuCyE, 33% (95% CI, 21% to 46%), than with BEAM, 59% (95% CI, 52% to 66%), with no differences in TRM or OS. BuCyE provided adequate disease control and safety in B cell NHL patients ≤ 65 years but produced worse PFS in HL patients when compared with BEAM.

Role of Maintenance Therapy after High-Dose Chemotherapy and Autologous Hematopoietic Cell Transplantation in Aggressive Lymphomas: A Systematic Review.

Significant uncertainty exists in regard to the efficacy of maintenance therapy after high-dose chemotherapy (HDC) as well as autologous stem cell transplantation (ASCT) for the treatment of patients with aggressive lymphoma. A systematic review was performed to evaluate the effectiveness of post-ASCT maintenance therapy in patients with relapsed/refractory lymphoma. A comprehensive literature search yielded 4476 studies and a total of 42 studies (11 randomized controlled trials [RCT], 9 retrospective comparative studies, and 22 single-arm studies) were included in the systematic review. There was significant heterogeneity in study design, chemotherapeutic regimens, post-ASCT maintenance strategies, patient enrollment criteria, and study endpoints. Our findings suggest that post-ASCT maintenance immune-targeting strategies, including PD-1/PD-L1 blocking antibodies, rituximab, and brentuximab, may improve progression-free survival but not overall survival. Collectively, the results indicate a need for testing new strategies with well-designed and adequately powered RCTs to better address the role of post-ASCT maintenance in relapsed/refractory lymphomas.

Factors associated with improved outcomes after second allogeneic hematopoietic cell transplantation for relapsed pediatric leukemia.

A second allogeneic (allo) hematopoietic cell transplant (HCT) is an important therapeutic consideration for patients relapsing after their first. We conducted a retrospective review of 41 pediatric patients with leukemia that underwent a second allo-HCT at our institution. Overall, 53.7 and 43.9 % of patients were alive and disease-free at 1 and 5 years, respectively, after the second allo-HCT. The factors affecting outcome by both univariate and multivariate analysis were interval between transplants and the use of a myeloablative conditioning (MAC) regimen prior to second transplant. Outcomes were inferior in patients who received their second transplant <6 months from their first HCT when compared to patients in whom the interval between HCTs was 6-12 or more than 12 months. Interval between HCTs was also significant when each type of leukemia (acute lymphoblastic leukemia (ALL) n = 21, acute myelogenous leukemia (AML) n = 11, and chronic myelogenous leukemia (CML) n = 7) was analyzed separately. In univariate analysis, use of the same donor and use of a matched sibling donor resulted in significant improved outcome. There was not a significant association between disease-free survival (DFS) and age, remission status, use of total body irradiation (TBI) before second HCT, or type of leukemia. Second allogeneic HCT can be a curative therapeutic option for leukemia patients relapsing after their first transplant. As more targeted therapies have become available, patients that relapse after first HCT are more likely to achieve remission. Therefore, it is anticipated that there will be more candidates for second HCT with improved performance and remission status, ultimately leading to a better outcome with the second HCT.

Plerixafor as a salvage mobilization strategy for haploidentical peripheral blood allogeneic stem cell transplantation.

In allogeneic stem cell mobilization, peripheral blood stem cell mobilization with filgrastim can be considered standard of care. Poor mobilizers may be at risk for inadequate stem cell collection during apheresis. He we present a successful case of salvage plerixafor use with filgrastim in a haploidentical identical transplant patient.

Extramedullary Breast Relapse of Acute Lymphoblastic Leukemia Controlled with a Second Allogeneic/Autologous Hematopoietic Cell Transplant.

Relapse of acute lymphoblastic leukemia (ALL) in the breast is uncommon and often precedes systemic relapse, resulting in poor survival. We report the development of breast involvement of ALL in a 20-year-old woman 32 months after a related allogeneic peripheral blood hematopoietic cell transplantation (PBHCT) in first remission. This extramedullary relapse occurred in the continuous presence of complete donor chimerism. After systemic re-induction chemotherapy and a second PBHCT using donor cells that had been cryopreserved at first transplant, our patient has remained in second complete remission for more than 44 months.

Phase 2 trial of CPX-351, a fixed 5:1 molar ratio of cytarabine/daunorubicin, vs cytarabine/daunorubicin in older adults with untreated AML.

CPX-351 is a liposomal formulation of cytarabine:daunorubicin designed to deliver synergistic drug ratios to leukemia cells. In this phase 2 study, newly diagnosed older acute myeloid leukemia (AML) patients were randomized 2:1 to first-line CPX-351 or 7+3 treatment. The goal was to determine efficacy and identify patient subgroups that may benefit from CPX-351 treatment. Response rate (complete remission + incomplete remission) was the primary end point, with event-free survival (EFS) and overall survival (OS) as secondary end points. The 126 patients entered were balanced for disease and patient-specific risk factors. Overall, CPX-351 produced higher response rates (66.7% vs 51.2%, P = .07), meeting predefined criteria for success (P < .1). Differences in EFS and OS were not statistically significant. A planned analysis of the secondary AML subgroup demonstrated an improved response rate (57.6% vs 31.6%, P = .06), and prolongation of EFS (hazard ratio [HR] = 0.59, P = .08) and OS (HR = 0.46, P = .01). Recovery from cytopenias was slower after CPX-351 (median days to absolute neutrophil count ≥1000: 36 vs 32; platelets >100 000: 37 vs 28) with more grade 3-4 infections but without increase in infection-related deaths (3.5% vs 7.3%) or 60-day mortality (4.7% vs 14.6%), indicating acceptable safety. These results suggest a clinical benefit with CPX-351, particularly among patients with secondary AML, and provide the rationale for a phase 3 trial currently underway in newly diagnosed secondary AML patients. This study is registered at Clinicaltrials.gov as #NCT00788892.

"Almost bleeding to death": the conundrum of acquired amegakaryocytic thrombocytopenia.

Acquired amegakaryocytic thrombocytopenia (AAT) is a rare hematological disorder causing severe thrombocytopenia and bleeding. Previous in vitro studies postulated both cell-mediated suppression of megakaryocytopoiesis in early megakaryocytic progenitor cells and humoral-mediated suppression by anti-thrombopoietin antibodies as possible etiologies of AAT. Patients with AAT usually present with severe bleeding and thrombocytopenia that is unresponsive to steroids and intravenous immunoglobulin (IVIG). Although standard guidelines have not been established for management of AAT, a few case reports have indicated a response to immunosuppressive treatment. The prompt recognition of this disease entity is essential in view of the substantial risk of morbidity and mortality from excessive bleeding. We report a case of AAT successfully treated with equine antithymocyte globulin (ATG) and cyclosporine (CSP).