Advanced Systemic Mastocytosis with associated haematological neoplasm: Treatment with avapritinib can facilitate successful bridge to allogeneic haematopoietic cell transplant.

Advanced systemic mastocytosis (AdvSM) is a rare, life-limiting mast cell (MC) neoplasm, with approximately 70% patients having an associated haematological neoplasm (AHN). Avapritinib, a selective tyrosine kinase inhibitor targeting KIT D816V, has shown potent activity translating clinically into durable responses in the phase 1 EXPLORER (NCT02561988) and phase 2 PATHFINDER (NCT03580655) studies. We report three patients with AdvSM-AHN on avapritinib who achieved complete remission (CR) of SM and were successfully bridged to allogeneic haematopoietic cell transplant (allo-HCT). Two cases additionally highlight the risk of clonal evolution within the AHN component and requirement for close monitoring while on targeted therapy.

The impact of improved JACIE standards on the care of related BM and PBSC donors.

Discrepancies exist between the care of unrelated donors (UDs) and related donors (RDs), particularly regarding medical suitability criteria, consenting procedures and donor follow-up. Changes to the most recent JACIE standards have addressed these issues. We studied 208 RDs who underwent PBSC or BM donation in a single centre during 2004-2013 to determine the impact of regulatory changes on donor care, and assessed the safety and efficacy of stem cell donation in donors not meeting UD medical suitability criteria. We observed significant improvements in donor consenting procedures (P=0.003) and donor follow-up (P=0.007) after stipulations in these areas were introduced. We saw a higher incidence of serious adverse events (SAEs) in RDs not meeting UD suitability criteria (P=0.018), and a higher incidence of SAEs in donors ⩾60 years (P=0.020). Haematopoietic progenitor cell donation is less safe in RDs who do not meet UD criteria for medical suitability. Although changes to JACIE standards have improved practice, development of specific medical suitability for RDs and guidelines around 'grey areas' where risks to a donor are unclear or theoretical, will be important in improving RD safety and standardising practice.

Pre-transplant MRD predicts outcome following reduced-intensity and myeloablative allogeneic hemopoietic SCT in AML.

The presence of minimal residual disease (MRD) by multiparametric flow cytometry (MFC) has been associated with adverse outcomes in AML patients treated with chemotherapy alone, but its impact in the setting of allogeneic hematopoietic SCT (HSCT) is less clear. We studied 88 patients who underwent myeloablative (MA) or reduced-intensity conditioned allogeneic HSCT for AML in first or subsequent remission at our center. MRD status was determined using three-color MFC on pre-HSCT BM aspirates, and patients were stratified by MRD status into MRD-negative, low-level MRD-positive (<1%) or high-level MRD-positive groups (1-4.9%). Two-year survival estimates in these groups were 66.8%, 51% and 30%, respectively (P=0.012), and 2-year estimates of relapse were 7.6, 37 and 70% (P<0.001). Pre-HSCT MRD was related to disease characteristics including secondary AML (P=0.002) and primary induction failure (P=0.005), but, despite these strong correlations, MRD remained independently associated with poorer survival in multivariate analysis (hazard ratio, 1.92; P=0.014). Pre-HSCT MRD is associated with adverse clinical outcomes in AML patients undergoing reduced-intensity or MA HSCT in first or subsequent remission and should be integrated into transplant strategies for patients with AML.

Mycophenolic acid trough level monitoring: relevance in acute and chronic graft versus host disease and its relation with albumin.

Mycophenolate mofetil (MMF) is used to treat acute and chronic graft versus host disease (GvHD). There is scant evidence in the literature about mycophenolic acid (MPA) trough level monitoring in GvHD. We therefore reviewed 32 patients treated with MMF for acute (n = 19) or chronic GvHD (n = 13). Twelve (63%) of 19 patients with acute GvHD and nine (69%) of 13 with chronic GvHD showed a good response. In all 21 patients who responded to MMF, their mean total MPA levels were therapeutic (1-3.5 mg/L), whereas five of 11 patients who did not respond had sub-therapeutic mean MPA levels (p = 0.002). Sixteen (66%) of 24 steroid refractory or dependent patients responded to MMF. Associations between the mean total MPA level for each patient and the corresponding mean serum albumin concentration showed therapeutic mean total MPA levels for all 23 patients with mean albumin ≥ 31 g/L but sub-therapeutic mean total MPA levels in five of nine patients with mean albumin <31 g/L (p = 0.0006). In conclusion, MMF is efficacious in steroid refractory and dependent acute or chronic GvHD with statistically significant correlation between therapeutic plasma total MPA trough levels and clinical response. Serum albumin levels should be taken into account when considering MMF dose adjustments.

Diverging effects of HLA-DPB1 matching status on outcome following unrelated donor transplantation depending on disease stage and the degree of matching for other HLA alleles.

Disease stage and recipient/donor human leukocyte antigen (HLA) matching are important determinants of outcome in transplantation using volunteer-unrelated donors (VUD). Matching for HLA-A, -B, -C, -DRB1, -DQB1 is beneficial, whereas the importance of DPB1 matching is more controversial. The impact of HLA matching status may differ dependent on disease stage. We investigated the outcome according to the degree of HLA matching at 6 loci, in 488 recipients of predominantly T-cell depleted bone marrow VUD transplants for leukaemia. Survival was significantly better in 12/12-matched transplants in those with early leukaemia (5 years: 63 versus 41% in 10/10 matched, P=0.006), but not late stage disease. Conversely, within the HLA-mismatched group (< or =9/10), there was a significant survival advantage to DPB1 mismatching (5 years: 39 versus 21% in DPB1 matched, P=0.008), particularly in late leukaemia (P=0.01), persisting in multivariate analysis (odds ratio 0.478; 95% confidence interval 0.30, 0.75; P=0.001). These novel findings suggest that the best outcome for patients with early leukaemia, with a 10/10-matched donor, is achieved by matching for DPB1. Conversely, our results suggest that in patients receiving an HLA-mismatched graft, the outcome is significantly better if they are also mismatched for DPB1. We recommend validation of these results in independent datasets.

An early CT-diagnosis-based treatment strategy for invasive fungal infection in allogeneic transplant recipients using caspofungin first line: an effective strategy with low mortality.

Empirical antifungal therapy is frequently used in allogeneic transplant patients who have persistent febrile neutropenia and can be associated with high cost, toxicity and breakthrough infections. There are limited reports of strategies for early diagnosis of invasive fungal infection (IFI) and, to our knowledge, no reports of treatment strategies based only on high-resolution computerized tomography (HRCT) scans. We used an early treatment strategy for IFI in 99 consecutive patients undergoing allogeneic transplantation. Patients received caspofungin if they had antibiotic-resistant neutropenic fever for more than 72 h and a positive HRCT scan. Fifty-three of 99 patients (54%) had antibiotic-resistant neutropenic fever at 72 h and would have received parenteral antifungal treatment if an empirical approach had been used. The HRCT-based strategy reduced the use of parenteral antifungal agents to 17/99 patients (17%), a 68% reduction. No subsequent diagnoses of IFI occurred within 100 days in patients with a negative HRCT. Only one patient died from IFI within 100 days. These data suggest that this non-empirical strategy may be feasible and that caspofungin may be effective in this setting. A randomized controlled trial is warranted to further assess these results.

The role of maintenance chemotherapy after autotransplantation for acute lymphoblastic leukemia in first remission: single-center experience of 100 patients.

A total of 100 adults with ALL in first CR received melphalan (110 mg/m(2)) with TBI followed by autologous marrow (n=35) or single-agent melphalan (200 mg/m(2)) followed by autologous blood stem cells (n=65). After adequate hematologic recovery, maintenance chemotherapy with 6-mercaptopurine, methotrexate and vincristine-prednisone was administered for 2 years. Six patients, all TBI recipients (P=0.001), died of toxicity. In total 70 patients received 6-mercaptopurine, 53 received methotrexate and 40 received vincristine-prednisone. The cumulative incidence of relapse at 7 years was 45%. The 7-year probabilities of disease-free survival (DFS) and overall survival were 45 and 48%. Age 30 years, >4 weeks to attain remission, and karyotypes t(4;11) and t(9;22) were associated with adverse outcome. Patients with 0 (standard risk), 1 (intermediate risk), and 2-3 (high risk) adverse features had 7-year cumulative incidences of relapse of 19, 53 and 82% (P<0.0001), and 7-year DFS probabilities of 73, 36 and 7% (P<0.0001). The 7-year probabilities of DFS for patients receiving 0, 1, 2 and 3 maintenance chemotherapy agents were 15, 29, 58 and 61% (P<0.0001). Maintenance chemotherapy intensity was an independent determinant of outcome in Cox analysis. Maintenance chemotherapy after autotransplantation reduces relapse and improves outcome in adult patients with ALL.

Prophylactic defibrotide in allogeneic stem cell transplantation: minimal morbidity and zero mortality from veno-occlusive disease.

Veno-occlusive disease (VOD) is a common and high-risk complication of allogeneic stem cell transplantation (SCT). Defibrotide has recently been used successfully to treat the disorder. We report on 58 patients who received defibrotide prophylaxis without concurrent heparin. No patients fulfilled the Baltimore criteria for VOD or died of the condition within 100 days of SCT. None of this group developed haemorrhagic complications secondary to defibrotide. These observations suggest that prophylaxis with defibrotide alone may reduce the incidence of VOD post-SCT although a randomised controlled trial is warranted to further evaluate its role.

Parainfluenza type 3 infection post stem cell transplant: high prevalence but low mortality.

Parainfluenza type 3 (PIV 3) is a well-recognized cause of respiratory illness after stem cell transplantation (SCT), with an estimated incidence of 2-7% and a high mortality rate associated with lower respiratory tract infection (LRTI). A 12-month retrospective study was undertaken in which 23 positive cases of PIV 3 occurred in SCT recipients. The frequency of infection was 36.1% in matched unrelated donor SCT recipients, 23.8% in sibling allogeneic SCT recipients and 2.3% in autologous transplant recipients. Seventeen cases were outpatient or community acquired despite standard infection control measures. Eleven patients only developed upper respiratory tract symptoms. LRTI symptoms developed in 12 patients, of whom eight had a new infiltrate on chest X-ray. Overall mortality at 30 days from PIV 3 diagnosis was 4% (one patient). Four patients died within 100 days of PIV 3 diagnosis, but PIV 3 was not believed to be the primary cause of death in any of these patients. Early ribavirin was used in eight patients and only one patient who received ribavirin died. These results suggest a higher prevalence of PIV 3 but a lower mortality than documented previously, particularly in allogeneic transplant recipients. The authors propose that the high prevalence reflects the unit's policy of active surveillance for respiratory viruses and the difficulty in preventing transmission of PIV 3, especially in the outpatient setting during an outbreak period. Ribavirin treatment may improve outcome in patients with LRTI but is not required in all patients with PIV 3.

Factors affecting reconstitution of the T cell compartment in allogeneic haematopoietic cell transplant recipients.

The factors affecting T cell reconstitution post haematopoietic cell transplantation (HCT) are not well characterised. We carried out a longitudinal analysis of T cell reconstitution in 32 HCT recipients during the first 12 months post transplant. We analysed reconstitution of naïve, memory and effector T cells, their diversity and monitored thymic output using TCR rearrangement excision circles (TRECs). Thymic-independent pathways were responsible for the rapid reconstitution of memory and effector T cells less than 6 months post HCT. Thymic-dependent pathways were activated between 6 and 12 months in the majority of patients with naïve T cell numbers increasing in parallel with TREC levels. Increasing patient age, chronic GVHD and T cell depletion (with or without pretransplant Campath-1H) predicted low TREC levels and slow naïve T cell recovery. Furthermore, increasing patient age also predicted high memory and effector T cell numbers. The effects of post HCT immunosuppression, total body irradiation, donor leucocyte infusions, T cell dose and post HCT infections on T cell recovery were also analysed. However, no effects of these single variables across a variety of different age, GVHD and T cell depletion groups were apparent. This study suggests that future analysis of the factors affecting T cell reconstitution and studies aimed at reactivating the thymus through therapeutic intervention should be analysed in age-, GVHD- and TCD-matched patient groups.

Identification of non-naïve CD4+CD45RA+ T cell subsets in adult allogeneic haematopoietic cell transplant recipients.

The study of thymic-dependent pathways of T cell reconstitution in T cell replete haematopoietic cell transplant (HCT) recipients in previous studies was complicated by the transfer of naïve CD4(+)CD45RA(+) T cells with the stem cell graft. However, direct quantification of thymic output has been enabled by measurement of T cell receptor excision circles (TREC). We analysed T cell reconstitution using T cell phenotyping and TREC quantification in 12 T cell-replete HCT recipients 6-53 years of age during the first 12 months post transplant. We have identified a novel subpopulation of CD4(+)CD45RA(+) T cells in the peripheral blood of these HCT recipients with expansions of this subset being more pronounced in older recipients. The recovery of classical naïve CD4(+)CD45RA(+) T cells was dependent on thymic output whereas this novel CD4(+)CD45RA(+) subpopulation arose independently of thymic output and displayed effector function and phenotype. These results suggest that CD4(+)CD45RA(+) effector populations exist, similar to the CD8(+)CD45RA(+) effector subset, and that the CD45RA antigen should not be used alone to define naïve CD4(+) T cells when monitoring T cell reconstitution in T cell replete HCT recipients. Furthermore, these results raise important questions regarding the role of the thymus in regulating T cell homeostasis in older HCT recipients and normal individuals.

Evidence for surfactant contributing to the gastric mucosal barrier of the horse.

This study was undertaken to determine the hydrophobicity of the luminal surface of the equine stomach and to elucidate the ultrastructure of the lining imparting that property. Gastric and duodenal mucosal samples from 5 horses were collected immediately after euthanasia and subjected to surface contact angle measurement using a goniometer. Gastric mucosal samples from 4 horses and a foal were examined by electron microscopy following a fixation procedure known to preserve phospholipids and oligolamellar structures. Contact angles for the equine gastric glandular mucosal surface (mean +/- s.e. 78.0 +/- 11.0 degrees) were greater than for the duodenum (33.4 +/- 8.7 degrees), (P = 0.003). The contact angles for gastric squamous tissue (50.4 +/- 4.5 degrees) tended to be greater than for duodenum (P = 0.15). Electron microscopy revealed the existence of surfactant as abundant osmiophilic phospholipid material within both squamous and glandular gastric mucosae. These results indicate the hydrophobic nature of the equine gastric mucosae. We propose that the water-repellent nature of the stomach contributes to the 'gastric mucosal barrier' and is imparted by surface-active phospholipid adsorbed to the surface. Phospholipids may also be utilised as a physical barrier to back-diffusion of acid by lining intracellular canaliculi and oxyntic ducts where other defence mechanisms are absent.

In vitro elution of gentamicin, amikacin, and ceftiofur from polymethylmethacrylate and hydroxyapatite cement.

OBJECTIVE: To compare the elution characteristics of ceftiofur and liquid and powdered gentamicin and amikacin from polymethylmethacrylate (PMMA) and from hydroxyapatite cement (HAC). METHODS: PMMA and HAC beads in triplicate were impregnated with various amounts and formulations of antibiotics. Beads were immersed in 5 mL of phosphate buffered saline that was replaced at 1, 3, 6, and 12 hours, and 1, 2, 3, 5, 7, 10, 14, 18, 22, 26, and 30 days. The eluent was stored at -70 degrees C until assayed within 2 weeks by microbiological assay (gentamicin and amikacin) or capillary electrophoresis (ceftiofur). RESULTS: Rate of elution for all beads was greatest within the first 24 hours. Cumulative release of total antibiotic dose from beads over 30 days was significantly greater from HAC than PMMA. Antibiotic elution was directly related to the amount of antibiotic incorporated into the cement. Powdered and liquid forms of gentamicin had similar elution rates from PMMA. Elution of amikacin from PMMA beads was greater when the powdered form was used compared with liquid amikacin. Eluent concentrations of ceftiofur were similar to those of the aminoglycosides during the first 3 to 7 days but then decreased precipitously by comparison. CONCLUSIONS: Elution of antibiotics from HAC was greater than from PMMA. Gentamicin- and amikacin-impregnated PMMA and HAC released bactericidal concentrations of antibiotic for at least 30 days. Ceftiofur-impregnated PMMA or HAC is unlikely to provide long-term bactericidal concentrations. CLINICAL RELEVANCE: Gentamicin and amikacin elute effectively from PMMA and HAC.

Modes of local drug delivery to the musculoskeletal system.

A number of methods for the local delivery of drugs to musculoskeletal tissues in the horse are now available. Further research is required to document the disposition of drugs delivered by such methods and to correlate this information with efficacy. Perhaps the greatest potential area for the methods discussed is the treatment of synovial and bone infections. To be able to provide high and sustained therapeutic concentrations of antimicrobials to the site of infection should increase the chances of success in such cases. These methods of drug delivery need to be used in conjunction with other management procedures, however, including bacterial culture and sensitivity procedures, systemic antimicrobials, surgical drainage, removal of dead bone or surgical implants, establishment of fracture stability, use of autogenous bone grafts, systemic NSAIDs, and rest.

Ultrastructure of the hydrophobic gastric surfactant barrier in the dog.

OBJECTIVES: To confirm the hydrophobicity of the luminal surface of the canine stomach and to elucidate the ultrastructure of the lining imparting that property. DESIGN AND PROCEDURES: Gastric and duodenal mucosal samples from eight dogs were collected immediately after euthanasia and subjected to contact angle measurement using a goniometer. Other samples were examined by electron microscopy following a fixation procedure known to preserve phospholipids and oligolamellar structures. RESULTS: Contact angles for the canine gastric mucosal surface (85.1 +/- 5.5) were significantly greater (P < 0.0001) than for the duodenum (24.0 +/- 1.7). Electron microscopy revealed the existence of surfactant as abundant osmiophilic phospholipid material within the gastric and duodenal mucosae. CONCLUSION: We have confirmed the hydrophobic nature of the canine gastric mucosa whereas the luminal surface of the duodenum is hydrophilic. We propose that the water-repellent nature of the canine gastric lining contributes to the 'gastric mucosal barrier' and is imparted by an oligolamellar layer of surface-active phospholipid ('gastric surfactant') adsorbed to the surface. Both gastric and duodenal mucosae may also utilise phospholipids as an intercellular defense mechanism in the event that tight junctions are breached by acid. It is tempting to speculate that a deficiency of gastric phospholipids may predispose dogs to ulcers. Further, exogenous administration of phospholipids may be useful in preventing gastric ulceration.