Timely diagnostics and safe procedures in children with anterior mediastinal masses (AMMs): a qualitative review of the AMM protocol at BC Children's Hospital in Vancouver BC.

The presence of an anterior mediastinal mass should prompt rapid triage, workup and treatment to effectively manage and prevent emergent complications. Implementation of an AMM protocol can ensure the response is standardized and coordinated. Importantly, such a protocol can encourage prompt multi-disciplinary communication to mitigate risks associated with procedures required for timely diagnosis. The aim of this review is to evaluate the BC Children's Hospital's Pediatric New/Suspected Anterior Mediastinal Mass (AMM) Protocol. Retrospective chart review was conducted for 18 patients admitted from February 2016 to May 2020 with AMM for whom the protocol was enacted. Primary parameters assessed presence of high-risk feature at time of presentation, time from admission and/or protocol activation to specific time points, including imaging, first diagnostic procedure, and diagnosis. Data regarding perioperative management, including anesthetic considerations and peri-operative complications, was also collected. Mean time from protocol activation to first diagnostic procedure and diagnosis were 1.88 days (range 0-7) and 2.24 days (range 0-7), respectively. The majority of procedures were conducted under sedation (n = 77, 64%), followed by general anesthetic (GA; n = 34, 28%) and local anesthetic (n = 10, 8%). Despite 15 cases having more than one high risk feature, pre-operative steroids were only administered for four of the total 158 procedures (3%) and extracorporeal life support (ECLS) and otolaryngology (ENT) were only required for immediate availability for seven procedures (4%). Furthermore, only 10 procedures (8%) had associated complications and none of these complications resulted in patient death. Our data demonstrate that implementation of a streamlined multi-disciplinary protocol can expedite time to diagnosis without impacting patient safety.

A Germline Mutation in the C2 Domain of PLCγ2 Associated with Gain-of-Function Expands the Phenotype for PLCG2-Related Diseases.

We report three new cases of a germline heterozygous gain-of-function missense (p.(Met1141Lys)) mutation in the C2 domain of phospholipase C gamma 2 (PLCG2) associated with symptoms consistent with previously described auto-inflammation and phospholipase Cγ2 (PLCγ2)-associated antibody deficiency and immune dysregulation (APLAID) syndrome and pediatric common variable immunodeficiency (CVID). Functional evaluation showed platelet hyper-reactivity, increased B cell receptor-triggered calcium influx and ERK phosphorylation. Expression of the altered p.(Met1141Lys) variant in a PLCγ2-knockout DT40 cell line showed clearly enhanced BCR-triggered influx of external calcium when compared to control-transfected cells. Our results further expand the molecular basis of pediatric CVID and phenotypic spectrum of PLCγ2-related defects.

Impact of renal impairment on outcomes after autologous stem cell transplantation in multiple myeloma: a multi-center, retrospective cohort study.

BACKGROUND: Renal impairment (RI) is a negative prognostic factor in Multiple Myeloma (MM) and affected patients are often excluded from autologous stem cell transplantation (ASCT). However, it remains unclear whether historically inferior outcome data still hold true. METHODS: From a total of 475 eligible MM patients who had undergone ASCT between 1998 and 2016, 374 were included in this multi-centric retrospective cohort study. Renal function was determined both at the time of MM diagnosis and ASCT by estimated glomerular filtration rate (eGFR according to the MDRD formula, RI defined as eGFR < 60 ml/min/1.73m2). Patients were categorized into 3 groups: A) no RI diagnosis and ASCT, B) RI at diagnosis with normalization before ASCT and C) RI both at the time of diagnosis and ASCT. Log-rank testing was used for overall and progression-free survival (OS, PFS) analysis. CONCLUSION: While severe RI at MM diagnosis confers a risk of shorter OS, MM progression after ASCT is not affected by any stage of renal failure. It can be concluded that ASCT can be safely carried out in MM patients with mild to moderate RI and should be pro-actively considered in those with severe RI. RESULTS: When comparing all groups, no difference in OS and PFS was found (p = 0.319 and p = 0.904). After further stratification according to the degree of RI at the time of diagnosis, an OS disadvantage was detected for patients with an eGFR < 45 ml/min/m2. PFS was not affected by any RI stage.

Plerixafor as preemptive strategy results in high success rates in autologous stem cell mobilization failure.

Plerixafor in combination with granulocyte-colony stimulating factor (G-CSF) is approved for autologous stem cell mobilization in poor mobilizing patients with multiple myeloma or malignant lymphoma. The purpose of this study was to evaluate efficacy and safety of plerixafor in an immediate rescue approach, administrated subsequently to G-CSF alone or chemotherapy and G-CSF in patients at risk for mobilization failure. Eighty-five patients mobilized with G-CSF alone or chemotherapy were included. Primary endpoint was the efficacy of the immediate rescue approach of plerixafor to achieve ≥2.0 × 106 CD34+ cells/kg for a single or ≥5 × 106 CD34+ cells/kg for a double transplantation and potential differences between G-CSF and chemotherapy-based mobilization. Secondary objectives included comparison of stem cell graft composition including CD34+ cell and lymphocyte subsets with regard to the mobilization regimen applied. No significant adverse events were recorded. A median 3.9-fold increase in CD34+ cells following plerixafor was observed, resulting in 97% patients achieving at least ≥2 × 106 CD34+ cells/kg. Significantly more differentiated granulocyte and monocyte forming myeloid progenitors were collected after chemomobilization whereas more CD19+ and natural killer cells were collected after G-CSF. Fifty-two patients underwent transplantation showing rapid and durable engraftment, irrespectively of the stem cell mobilization regimen used. The addition of plerixafor in an immediate rescue model is efficient and safe after both, G-CSF and chemomobilization and results in extremely high success rates. Whether the differences in graft composition have a clinical impact on engraftment kinetics, immunologic recovery, and graft durability have to be analysed in larger prospective studies.

Clofarabine/cyclophosphamide for debulking before stem cell transplantation.

BACKGROUND: Allogeneic haematopoietic stem cell transplantation (HSCT) is the only curative rescue therapy for patients (pts) with chemotherapy-refractory acute leukaemia. Disease control prior to HSCT is essential for long-term disease-free survival after HSCT. PATIENTS AND METHODS: We have retrospectively analysed the outcome of 20 pts aged 21-64 years with refractory leukaemia (acute myeloid leukaemia, n = 16; acute lymphatic leukaemia, n = 4) who received debulking therapy with clofarabine (10 mg/m², days 1-4) and cyclophosphamide (200 mg/m², days 1-4; ClofCy) prior to HSCT. RESULTS: Clofarabine/cyclophosphamide (1-4 cycles) was well tolerated and resulted in a substantial reduction of leukaemic cells in all pts. HSCT was performed in 15 of 20 pts. After HSCT (myeloablative, n = 9; dose-reduced, n = 6), all pts showed engraftment and full donor chimerism (related donors, n = 4 or unrelated donors, n = 11) and all pts achieved complete haematologic remission (CR). The median survival after HSCT is 531 days (range: 48-1462 days), and six pts are still alive after a median of 1245 days. Seven pts died after they had relapsed between days +152 and +1496. One patient died from acute graft-versus-host disease (day +48) and one from systemic fungal infection (day +87). CONCLUSION: Clofarabine/cyclophosphamide is a novel effective treatment approach for pts with chemotherapy-refractory acute leukaemia prior to HSCT. Whether this novel debulking protocol leads to improved long-term outcome in pts with refractory leukaemias remains to be determined in forthcoming clinical studies.

Fatal skin and pulmonary infection caused by Hormographiella aspergillata in a leukaemic patient: case report and literature overview.

Invasive systemic fungal infections are a major cause of morbidity and mortality in patients after hematopoietic stem cell transplantation. We report the case of a fatal infection with Hormographiella aspergillata in a patient undergoing allogenic peripheral blood stem cell transplantation for acute myeloid leukaemia.

Mitogen-induced defective mitosis transforms neural progenitor cells.

BACKGROUND: Chromosome instability (CIN) with recurrent copy number alterations is a feature of many solid tumors, including glioblastoma (GBM), yet the genes that regulate cell division are rarely mutated in cancers. Here, we show that the brain-abundant mitogen, platelet-derived growth factor-A (PDGFA) fails to induce the expression of kinetochore and spindle assembly checkpoint genes leading to defective mitosis in neural progenitor cells (NPCs). METHODS: Using a recently reported in vitro model of the initiation of high-grade gliomas from murine NPCs, we investigated the immediate effects of PDGFA exposure on the nuclear and mitotic phenotypes and patterns of gene and protein expression in NPCs, a putative GBM cell of origin. RESULTS: NPCs divided abnormally in defined media containing PDGFA with P53-dependent effects. In wild-type cells, defective mitosis was associated with P53 activation and cell death, but in some null cells, defective mitosis was tolerated. Surviving cells had unstable genomes and proliferated in the presence of PDGFA accumulating random and clonal chromosomal rearrangements. The outcome of this process was a population of tumorigenic NPCs with recurrent gains and losses of chromosomal regions that were syntenic to those recurrently gained and lost in human GBM. By stimulating proliferation without setting the stage for successful mitosis, PDGFA-transformed NPCs lacking P53 function. CONCLUSIONS: Our work describes a mechanism of transformation of NPCs by a brain-associated mitogen, raising the possibility that the unique genomic architecture of GBM is an adaptation to defective mitosis that ensures the survival of affected cells.

BendaEAM versus BEAM as conditioning regimen for ASCT in patients with relapsed lymphoma (BEB): a multicentre, randomised, phase 2 trial.

Background: Replacement of carmustine (BCNU) in the BEAM regimen (BCNU, etoposide, cytarabine, melphalan) with bendamustine (BendaEAM) before autologous stem cell transplantation (ASCT) is feasible in lymphoma. However, randomised trials are lacking. Here, we present the first trial addressing this topic. Methods: This multicentre, randomised, phase 2 study (BEB-trial) conducted at four haematological centres in Austria and Switzerland compares BEAM with BendaEAM in patients with relapsed lymphoma. Both regimens were administered intravenously before ASCT, in BEAM according to the standard protocol (300 mg/m2 BCNU on day -6), in BendaEAM, BCNU was replaced by 200 mg/m2 bendamustine given on days -7 and -6. Eligible patients were aged 18-75 years and had mantle cell lymphoma, diffuse large B-cell lymphoma, or follicular lymphoma in first or second remission or chemosensitive relapse. The primary endpoint of the study was to evaluate whether replacement of BCNU by bendamustine reduces lung toxicity, defined as a decrease of the diffusion capacity of the lung for carbon monoxide by at least 20% at three months after ASCT. Data analyses were performed on an intention-to-treat basis. This study is registered with ClinicalTrials.gov, number NCT02278796, and is complete. Findings: Between April 20, 2015, and November 28, 2018, 108 patients were enrolled; of whom 53 were randomly assigned to receive BendaEAM (36 male, 17 female) and 55 to receive BEAM (39 male, 16 female). All patients engrafted rapidly. Lung toxicity did not differ between groups (BendaEAM: n = 8, 19.5%; BEAM: n = 11, 25.6%; risk difference = -6.1%: 95% confidence interval: -23.9% to 11.7%). Acute toxicities of at least grade 3 were comparable in both groups (BendaEAM: 35.8%, BEAM: 30.9%). Overall survival (BendaEAM: 92.5%, BEAM: 89.1%) and complete remission (BendaEAM: 76.7%, BEAM: 74.3%) after 1 year (median follow-up: 369 days) were similar. No difference in quality of life was observed. Interpretation: Results were similar for both regimens in terms of survival and response rates. A phase 3 non-inferiority study is required to investigate whether BendaEAM can be considered as an alternative to BEAM. Funding: Mundipharma.

Frequency and prognostic value of D alloantibodies after D-mismatched allogeneic hematopoietic stem cell transplantation after reduced-intensity conditioning.

BACKGROUND: Due to the fact that the ABO and D system is inherited independently from the HLA system, approximately 40% of allogeneic hematopoietic stem cell transplants (HSCT) are performed across the blood group barrier. Reports on the development of de novo anti-D in patients undergoing reduced-intensity conditioning (RIC) followed by D-mismatched allogeneic HSCT are rare. The objective of this study was to evaluate the frequency of anti-D alloimmunization after D-mismatched HSCT following RIC and its prognostic impact on transplant outcome. STUDY DESIGN AND METHODS: Forty patients with hematologic diseases who underwent D-mismatched HSCT were retrospectively analyzed: 19 D- patients with a D+ donor and 21 D+ patients with a D- donor. Routine serologic testing for blood group typing and antibody screening was performed by a column agglutination method every time when transfusion of red blood cell units was requested and in the posttransplantation course to demonstrate establishment of donor ABO type and to detect alloimmunization. RESULTS: After a median serologic follow-up of 21 (range, 0 to 73) months after HSCT, anti-D was identified in 2 of 21 (10%) D+ patients receiving a D- transplant, 23 and 34 months after HSCT. None of the 19 D- patients with a D+ donor developed an anti-D. CONCLUSION: We observed an infrequent de novo anti-D formation that is more likely in D+ recipients of D- grafts. However, the development of anti-D does not normally impair the transplant outcome and is not of clinical relevance in the posttransplant course.

Clinical and cost outcomes following genomics-informed treatment for advanced cancers.

BACKGROUND: Single-arm trials are common in precision oncology. Owing to the lack of randomized counterfactual, resultant data are not amenable to comparative outcomes analyses. Difference-in-difference (DID) methods present an opportunity to generate causal estimates of time-varying treatment outcomes. Using DID, our study estimates within-cohort effects of genomics-informed treatment versus standard care on clinical and cost outcomes. METHODS: We focus on adults with advanced cancers enrolled in the single-arm BC Cancer Personalized OncoGenomics program between 2012 and 2017. All individuals had a minimum of 1-year follow up. Logistic regression explored baseline differences across patients who received a genomics-informed treatment versus a standard care treatment after genomic sequencing. DID estimated the incremental effects of genomics-informed treatment on time to treatment discontinuation (TTD), time to next treatment (TTNT), and costs. TTD and TTNT correlate with improved response and survival. RESULTS: Our study cohort included 346 patients, of whom 140 (40%) received genomics-informed treatment after sequencing and 206 (60%) received standard care treatment. No significant differences in baseline characteristics were detected across treatment groups. DID estimated that the incremental effect of genomics-informed versus standard care treatment was 102 days (95% CI: 35, 167) on TTD, 91 days (95% CI: -9, 175) on TTNT, and CAD$91,098 (95% CI: $46,848, $176,598) on costs. Effects were most pronounced in gastrointestinal cancer patients. CONCLUSIONS: Genomics-informed treatment had a statistically significant effect on TTD compared to standard care treatment, but at increased treatment costs. Within-cohort evidence generated through this single-arm study informs the early-stage comparative effectiveness of precision oncology.

Function of platelets in apheresis platelet concentrates and in patient blood after transfusion as assessed by Impact-R.

BACKGROUND: Platelet (PLT) transfusion is a mainstream therapy for preventing or treating bleeding episodes in patients with thrombocytopenia. The efficacy is usually estimated from the corrected count increment of PLTs after transfusion, which does not assess PLT function. We therefore evaluated PLT function in blood samples of patients with thrombocytopenia before and after transfusion. STUDY DESIGN AND METHODS: PLT function was assessed in 24 chemotherapy-treated patients and in the PLT concentrates (PCs) by the Impact-R (DiaMed). This device evaluates PLT adhesion and aggregation recorded as surface coverage (%) and size of aggregates (AS microm(2)). P-selectin expression was determined by flow cytometry. RESULTS: The PCs were stored for a median of 70 hours before transfusion. An analysis stratified by the median storage of PCs (<70 hr or >70 hr) showed no differences in the SC, the AS, and P-selectin expression between these concentrates' groups. Transfusion resulted in an increase of adhering PLTs in the patients after transfusion. There were no differences in the AS and in P-selectin expression before and after transfusion, but the AS increased after transfusion upon ex vivo exposure to adenosine 5'-diphosphate. P-selectin expression was significantly lower in the patient group receiving PCs stored for more than 70 hours. CONCLUSION: The current trial shows the feasibility of using the Impact-R to assess the function of transfused PLTs in the patient's blood stream.

In vitro modeling of glioblastoma initiation using PDGF-AA and p53-null neural progenitors.

BACKGROUND: Imagining ways to prevent or treat glioblastoma (GBM) has been hindered by a lack of understanding of its pathogenesis. Although overexpression of platelet derived growth factor with two A-chains (PDGF-AA) may be an early event, critical details of the core biology of GBM are lacking. For example, existing PDGF-driven models replicate its microscopic appearance, but not its genomic architecture. Here we report a model that overcomes this barrier to authenticity. METHODS: Using a method developed to establish neural stem cell cultures, we investigated the effects of PDGF-AA on subventricular zone (SVZ) cells, one of the putative cells of origin of GBM. We microdissected SVZ tissue from p53-null and wild-type adult mice, cultured cells in media supplemented with PDGF-AA, and assessed cell viability, proliferation, genome stability, and tumorigenicity. RESULTS: Counterintuitive to its canonical role as a growth factor, we observed abrupt and massive cell death in PDGF-AA: wild-type cells did not survive, whereas a small fraction of null cells evaded apoptosis. Surviving null cells displayed attenuated proliferation accompanied by whole chromosome gains and losses. After approximately 100 days in PDGF-AA, cells suddenly proliferated rapidly, acquired growth factor independence, and became tumorigenic in immune-competent mice. Transformed cells had an oligodendrocyte precursor-like lineage marker profile, were resistant to platelet derived growth factor receptor alpha inhibition, and harbored highly abnormal karyotypes similar to human GBM. CONCLUSION: This model associates genome instability in neural progenitor cells with chronic exposure to PDGF-AA and is the first to approximate the genomic landscape of human GBM and the first in which the earliest phases of the disease can be studied directly.

Sorafenib Maintenance After Allogeneic Hematopoietic Stem Cell Transplantation for Acute Myeloid Leukemia With FLT3-Internal Tandem Duplication Mutation (SORMAIN).

PURPOSE: Despite undergoing allogeneic hematopoietic stem cell transplantation (HCT), patients with acute myeloid leukemia (AML) with internal tandem duplication mutation in the FMS-like tyrosine kinase 3 gene (FLT3-ITD) have a poor prognosis, frequently relapse, and die as a result of AML. It is currently unknown whether a maintenance therapy using FLT3 inhibitors, such as the multitargeted tyrosine kinase inhibitor sorafenib, improves outcome after HCT. PATIENTS AND METHODS: In a randomized, placebo-controlled, double-blind phase II trial (SORMAIN; German Clinical Trials Register: DRKS00000591), 83 adult patients with FLT3-ITD-positive AML in complete hematologic remission after HCT were randomly assigned to receive for 24 months either the multitargeted and FLT3-kinase inhibitor sorafenib (n = 43) or placebo (n = 40 placebo). Relapse-free survival (RFS) was the primary endpoint of this trial. Relapse was defined as relapse or death, whatever occurred first. RESULTS: With a median follow-up of 41.8 months, the hazard ratio (HR) for relapse or death in the sorafenib group versus placebo group was 0.39 (95% CI, 0.18 to 0.85; log-rank P = .013). The 24-month RFS probability was 53.3% (95% CI, 0.36 to 0.68) with placebo versus 85.0% (95% CI, 0.70 to 0.93) with sorafenib (HR, 0.256; 95% CI, 0.10 to 0.65; log-rank P = .002). Exploratory data show that patients with undetectable minimal residual disease (MRD) before HCT and those with detectable MRD after HCT derive the strongest benefit from sorafenib. CONCLUSION: Sorafenib maintenance therapy reduces the risk of relapse and death after HCT for FLT3-ITD-positive AML.

Awareness of predatory journals and open access among medical oncologists: results of an online survey.

Introduction: Predatory journals harm the integrity of science as principles of 'good scientific practice' are bypassed by omitting a proper peer-review process. Therefore, we aimed to explore the awareness of predatory journals among oncologists. Methods: An online survey among oncologists working in Germany or Austria of various professional surroundings was conducted between October 2018 and April 2019. Results: One hundred and eighty-eight participants (55 women (29.2%), 128 men (68.1%)) completed the questionnaire. 41 (21.8%) participants indicated to work in a hospital, 24 (12.8%) in private practice and 112 (59.6%) in a university hospital. 98.9% of participants indicated to actively read scientific articles and consider them in clinical decision-making (96.3%). 90.4% of participants indicated to have scientific experience by publishing papers in journals with peer-review system. The open-access system was known by 170 (90.4%), predatory journals by 131 (69.7%) and Beall's list by 52 participants (27.7%). Predatory journals were more likely to be known by participants with a higher number of publications (p<0.001), with more high-impact publications (p=0.005) and with recent publications (p<0.001). Awareness of predatory journals did not correlate with gender (p=0.515) or translation of scientific literature into clinical practice (p=0.543). Conclusions: The problematic topic of 'predatory journals' is still unknown by a considerable amount of oncologist, although the survey was taken in a cohort of oncologists with scientific experience. Dedicated educational initiatives are needed to raise awareness of this problem and to aid in the identification of predatory journals for the scientific oncology community.

Red blood cell transfusion dependence and outcome after allogeneic peripheral blood stem cell transplantation in patients with de novo myelodysplastic syndrome (MDS).

The prognosis of patients with de novo myelodysplastic syndrome (MDS) who are red blood cell transfusion-dependent (TD) and receive supportive care is inferior to that of patients who do not require transfusions. Whether TD also affects outcome after allogeneic transplantation is unknown. Consequently, in 172 de novo MDS patients (median age, 51 years), we analyzed the impact of TD on outcome after high-dose conditioning and allogeneic peripheral blood stem cell transplantation (PBSCT). With a median follow-up of 37 months, the probability of 3-year overall survival (OS) did not differ significantly between patients who were TD and those who were not TD before PBSCT (P=.1); however, transfusion burden, as reflected by ferritin levels, was correlated with a greater probability of severe acute graft-versus-host disease (aGVHD; P=.03) and a higher comorbidity index (P=.01), and OS was inferior in those patients with a ferritin level>1000 microg/L before PBSCT (P=.03). In multivariate analysis, only marrow myeloblast count (P=.01) and comorbidity index (P=.001) had a significant impact on OS. Our data do not identify TD as an independent negative prognostic factor for outcome after allogeneic PBSCT' however, iron overload (presumably transfusion-related) may contribute to poor transplantation success by adding to the overall comorbidities. Whether clinical intervention in the form of iron chelation can improve the outcome of allogeneic PBSCT in TD patients with MDS remains to be determined.

Effects of the CD33-targeted drug gemtuzumab ozogamicin (Mylotarg) on growth and mediator secretion in human mast cells and blood basophils.

OBJECTIVE: Mylotarg (gemtuzumab ozogamicin [GO]) has recently been introduced as a novel CD33-targeting drug in clinical hematology. However, despite efficacy, GO produces significant side effects including an infusion syndrome. We have recently shown that mast cells (MCs) and basophils (BAs) express CD33. In the present study, we investigated the effects of GO on growth and mediator secretion in MCs and BAs. METHODS: Growth-inhibitory effects of GO on neoplastic MCs (HMC-1) and BAs (KU812) as well as cord blood-derived MC and BA progenitor cells were determined by counting cell numbers and the numbers of apoptotic cells. The amount of histamine secreted from primary MCs and BAs was measured by radioimmunoassay after incubation of cells with GO alone or GO together with an anti-immunoglobulin E (IgE) antibody. RESULTS: MCs and BAs as well as HMC-1 cells and KU812 cells were found to express CD33 mRNA and the CD33 protein. GO was found to inhibit the growth of HMC-1 cells and KU812 cells as well as stem cell factor-dependent differentiation of MCs and interleukin-3-induced growth of BAs from their cord blood-derived progenitors. The GO-induced inhibition of growth of neoplastic cells was found to be associated with induction of apoptosis. GO neither induced secretion of histamine from MCs or BAs nor upregulated the anti-IgE-induced release of histamine in these cells. CONCLUSIONS: GO counteracts growth of normal and neoplastic MCs and BAs without inducing rapid release of histamine. The exact value of GO as a targeted drug for the treatment of high-grade MC or BA neoplasms remains to be determined.

ABT-888 restores sensitivity in temozolomide resistant glioma cells and xenografts.

BACKGROUND: Temozolomide (TMZ) is active against glioblastomas (GBM) in which the O6-methylguanine-DNA methyltransferase (MGMT) gene is silenced. However, even in responsive cases, its beneficial effect is undermined by the emergence of drug resistance. Here, we tested whether inhibition of poly (ADP-ribose) polymerase-1 and -2 (PARP) enhanced the effectiveness of TMZ. METHODS: Using patient derived brain tumor initiating cells (BTICs) and orthotopic xenografts as models of newly diagnosed and recurrent high-grade glioma, we assessed the effects of TMZ, ABT-888, and the combination of TMZ and ABT-888 on the viability of BTICs and survival of tumor-bearing mice. We also studied DNA damage repair, checkpoint protein phosphorylation, and DNA replication in mismatch repair (MMR) deficient cells treated with TMZ and TMZ plus ABT-888. RESULTS: Cells and xenografts derived from newly diagnosed MGMT methylated high-grade gliomas were sensitive to TMZ while those derived from unmethylated and recurrent gliomas were typically resistant. ABT-888 had no effect on the viability of BTICs or tumor bearing mice, but co-treatment with TMZ restored sensitivity in resistant cells and xenografts from newly diagnosed unmethylated gliomas and recurrent gliomas with MSH6 mutations. In contrast, the addition of ABT-888 to TMZ had little sensitizing effect on cells and xenografts derived from newly diagnosed methylated gliomas. In a model of acquired TMZ resistance mediated by loss of MMR gene MSH6, re-sensitization to TMZ by ABT-888 was accompanied by persistent DNA strand breaks, re-engagement of checkpoint kinase signaling, and interruption of DNA synthesis. CONCLUSION: In laboratory models, the addition of ABT-888 to TMZ overcame resistance to TMZ.

HLA-C KIR-Ligands Determine the Impact of Anti-Thymocyte Globulin (ATG) on Graft versus Host and Graft versus Leukemia Effects Following Hematopoietic Stem Cell Transplantation.

Rabbit anti-thymocyte globulins (ATGs) are widely used for the prevention of acute and chronic graft versus host disease (aGVHD, cGVHD) following allogeneic hematopoietic stem cell transplantation (HSCT). However, most prospective and retrospective studies did not reveal an overall survival (OS) benefit associated with ATG. Homozygosity for human leukocyte antigen (HLA)-C group 1 killer-cell immunoglobulin-like receptor ligands (KIR-L), i.e. C1/1 KIR-L status, was recently shown to be a risk factor for severe aGVHD. Congruously, we have previously reported favorable outcomes in C1/1 recipients after ATG-based transplants in a monocentric analysis. Here, within an extended cohort, we test the hypothesis that incorporation of ATG for GVHD prophylaxis may improve survival particularly in HSCT recipients with at least one C1 KIR-ligand. Retrospectively, 775 consecutive allogeneic (excluding haploidentical) HSCTs were analyzed, including peripheral blood and bone marrow grafts for adults with hematological diseases at two Austrian HSCT centers. ATG-Fresenius/Grafalon, Thymoglobuline, and alemtuzumab were applied in 256, 87, and 7 transplants, respectively (subsequently summarized as "ATG"), while 425 HSCT were performed without ATG. Median follow-up of surviving patients is 48 months. Adjusted for age, disease-risk, HLA-match, donor and graft type, sex match, cytomegalovirus serostatus, conditioning intensity, and type of post-grafting GVHD prophylaxis, Cox regression analysis of the entire cohort (n = 775) revealed a significant association of ATG with decreased non-relapse mortality (NRM) (risk ratio (RR), 0.57; p = 0.001), and overall mortality (RR, 0.71; p = 0.014). Upon stratification for HLA-C KIR-L, the greatest benefit for ATG emerged in C1/1 recipients (n = 291), by reduction of non-relapse (RR, 0.34; p = 0.0002) and overall mortality (RR, 0.50; p = 0.003). Less pronounced, ATG decreased NRM (RR, 0.60; p = 0.036) in HLA-C group 1/2 recipients (n = 364), without significantly influencing overall mortality (RR, 0.70; p = 0.065). After exclusion of higher-dose ATG-based transplants, serotherapy significantly improved both NRM (RR, 0.54; p = 0.019; n = 322) and overall mortality (RR, 0.60; p = 0.018) in C1/2 recipients as well. In both, C1/1 (RR, 1.70; p = 0.10) and particularly in C1/2 recipients (RR, 0.94; p = 0.81), there was no statistically significant impact of ATG on relapse incidence. By contrast, in C2/2 recipients (n = 121), ATG neither reduced NRM (RR, 1.10; p = 0.82) nor overall mortality (RR, 1.50; p = 0.17), but increased the risk for relapse (RR, 4.38; p = 0.02). These retrospective findings suggest ATG may provide a survival benefit in recipients with at least one C1 group KIR-L, by reducing NRM without significantly increasing the relapse risk.

Immunohistochemical detection of histidine decarboxylase in neoplastic mast cells in patients with systemic mastocytosis.

Synthesis of histamine in hematopoietic progenitor cells may be one of the earliest events in mastopoiesis. We therefore asked whether the key enzyme involved in histamine production, histidine decarboxylase (HDC), can be used as an immunohistochemical marker for the detection of immature neoplastic mast cells (MC) in patients with MC-proliferative disorders. To address this question, we examined bone marrow biopsy specimens in a cohort of 102 patients with mastocytosis using an antibody against HDC. Independent of the maturation stage of MC, the anti-HDC antibody produced clear diagnostic staining results in all patients with systemic MC disease examined including those with MC leukemia and MC sarcoma, in which MCs are particularly immature. In these patients, expression of HDC was reconfirmed at the messenger RNA level by reverse transcriptase polymerase chain reaction analyses performed with RNA of highly enriched CD117(+) MC. In summary, HDC is expressed in neoplastic MC in patients with systemic mastocytosis independent of the maturation stage of cells or the variant of disease. Histidine decarboxylase should therefore be considered as a new MC marker in the screen panel of antigens used to diagnose high-grade MC malignancies.

Identification of basogranulin (BB1) as a novel immunohistochemical marker of basophils in normal bone marrow and patients with myeloproliferative disorders.

In myeloproliferative disorders (MPDs), basophils typically increase in number in the bone marrow (BM) and blood. In chronic myeloid leukemia (CML), basophilia is a diagnostic and prognostic variable. However, no reliable approach for routine detection and enumeration of basophils in BM sections is available. We applied the antibasogranulin antibody BB1 on paraffin-embedded BM sections in 21 control samples (normal BM), 45 patients with CML, 9 with chronic idiopathic myelofibrosis, 11 with polycythemia vera, 19 with essential thrombocythemia, and 7 with indolent systemic mastocytosis. As assessed by immunostaining of serial BM sections, BB1+ cells coexpressed myeloperoxidase, histidine decarboxylase, and leukosialin but did not express B- or T-cell-restricted antigens. BB1+ BM cells were found to be highly elevated in patients with CML compared with normal BM or other MPDs, with maximum counts found in accelerated phase CML (median, 160 cells/mm(2)). In summary, BB1 (basogranulin) is a new immunohistochemical basophil marker that should allow quantification of basophils in CML at diagnosis and during therapy.