Abstract: Background Current response criteria for AML were established for and validated in younger patients (pts) fit for and treated with intensive chemotherapy (IC) in an era before hypomethylating agents (HMA) were available. According to these criteria: 1 Achievement of morphologic complete response (CR; defined as bone marrow blasts [BMB] 〈 5%, absolute neutrophil count 〉 1.0G/L, platelets ≥100G/L and red blood cell transfusion independence) is a prerequisite for cure, and is deemed the sole outcome associated with improved overall survival (OS)1 2 Pts without morphologic CR are considered non-responders1 3 Morphologic leukemia free state (MLFS; defined as 〈 5% BMB, irrespective of cytopenias) is considered inferior to CR 4 Hematologic improvement (HI) without BMB clearance is considered treatment failure1,2 However, evidence is accumulating that these definitions may not be applicable to older AML pts treated with HMA. For example, achievement of CR with HMA may not be necessary for clinical benefit and prolonged OS.3-5 We have previously shown that older AML pts achieving HI according to myelodysplastic syndrome (MDS) criteria6 have clinical benefit from extended azacitidine (AZA) treatment.3,4 In addition, treatment goals and modalities differ for HMA vs IC. Thus, the question arises whether current response criteria remain valid for older AML pts unfit for IC. Aims and methods To define new response criteria, including the 1st criteria for assessment of HI, for older AML pts unfit for IC with the intention of keeping them as simple to implement as possible. Human errors in response assessment according to these proposed criteria were excluded by the development of algorithms for automated computational calculation from data entered into the eCRF. We next assessed the supplementary value of HI in addition to BMB reduction, as well as the value of HI irrespective of BMB reduction, with regards to predicting treatment outcomes. Results In total, 193 AML pts receiving AZA 1st line were included in this analysis. Baseline and treatment characteristics were mostly comparable to those of AML pts included in a recent phase 3 clinical trial (Fig 1).7 Overall, 5 categories of HI and hematologic progression were defined, using: erythrocytes (E), platelets (P), neutrophils (N), peripheral blood blasts, and elevated white blood cells (Fig 2). We based our definitions on IWG 2006 MDS criteria and adapted these for the more aggressive disease biology and kinetics of AML, and treatment goals and modalities of HMA. Our data indicate that: 1 AML pts achieving HI (irrespective of BMB reduction) had significantly longer OS than those without HI (16.1 vs 6.0 mo, p 〈 0.001; Fig 3A) 2 OS was prolonged irrespective of the cell lineage in which HI occurred (17.1, 17.5 and 18.0 mo for pts with HI-N, HI-E or HI-P, respectively) 3 OS correlated with the number of cell lineages/types in which HI was achieved (6.0 vs 14.4 vs 19.7 mo [p 〈 0.001] for HI in 0 vs 1-2 vs 〉 2 lineages/types; Fig 3B) 4 Pts with MLFS did not have worse OS than pts with CR (Fig 3C) 5 Definition of response according to our proposed criteria resulted in clinically meaningful separation of 3 response types with significant differences in median OS: 23.0 (CR or MLFS) vs 13.5 (HI and not CR or MLFS) vs 4.4 mo (non-responders) (p 〈 0.001; Fig 3D) Conclusions While achievement of CR according to IWG 2003 criteria1 remains the primary goal for AML pts treated with IC, we guardedly introduce new response criteria for pts unfit for IC treated with non-curative treatment such as HMA. Applying these criteria to our large real world cohort, we show that pts achieving HI in the absence of BMB clearance (considered non-responders using current criteria)1, had a significant survival benefit from continued AZA treatment compared to pts with no HI. We conclude that these patients should be considered as responders and kept on treatment, and hypothesize that achievement of HI could be used as a surrogate parameter for response in pts unable or unwilling to undergo BM biopsy for response assessment. This proposal requires concerted validation efforts and we hope that our data stimulate cooperations. References 1 Cheson BD JCO 2003;21:4642 2 Lopez G Blood 2001;98:329;abs 1388 3 Pleyer L J Hematol Oncol 2013;6:32 4 Pleyer L Ann Hematol 2014;93:1825 5 Schuh AC Haematologica 2015;100:abs P575 6 Cheson BD Blood 2006;108:419 7 Dombret H Blood 2015;126:291 Disclosures Pleyer: AOP Orphan Pharmaceuticals: Honoraria; Novartis: Consultancy, Honoraria; Bristol-Myers Squibb: Consultancy, Honoraria; Celgene: Consultancy, Honoraria. Off Label Use: Vidaza (azacitidine) is indicated for the treatment of adult AML patients who are not eligible for hematopoietic stem cell transplantation with 20-30% blasts and multi-lineage dysplasia, according to WHO classification. This cohort also includes AML patients with 〉 30% bone marrow blasts.. Burgstaller:Celgene: Consultancy, Honoraria, Research Funding; Novartis: Honoraria; Mundipharma: Honoraria; AOP Orphan Pharmaceuticals: Honoraria, Research Funding. Girschikofsky:Pfizer: Honoraria, Research Funding; Mundipharma: Consultancy, Honoraria. Sill:Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding. Thaler:AOP Orphan: Research Funding. Halter:Medical University Innsbruck: Employment. Zebisch:Celgene: Honoraria. Pichler:Celgene: Honoraria. Pfeilstöcker:Celgene: Consultancy, Honoraria, Research Funding, Speakers Bureau; Novartis: Consultancy, Speakers Bureau. Autzinger:Wilhelminenspital: Employment. Lang:Celgene: Consultancy. Geissler:Celgene: Membership on an entity's Board of Directors or advisory committees. Geissler:Klinikum Klagenfurt: Employment. Sperr:Celgene: Consultancy; Ariad: Consultancy. Hojas:LKH Fürstenfeld: Employment. Greil:Amgen: Honoraria, Research Funding; Pfizer: Honoraria, Research Funding; Boehringer-Ingelheim: Honoraria; Astra-Zeneca: Honoraria; Cephalon: Consultancy, Honoraria, Research Funding; Celgene: Consultancy; Ratiopharm: Research Funding; GSK: Research Funding; Sanofi Aventis: Honoraria; Novartis: Honoraria; Janssen-Cilag: Honoraria; Genentech: Honoraria, Research Funding; Eisai: Honoraria; Mundipharma: Honoraria, Research Funding; Merck: Honoraria; Bristol-Myers-Squibb: Consultancy, Honoraria; AOP Orphan: Research Funding; Roche, Celgene: Honoraria, Research Funding.

Abstract: Background In the Phase III trial (AML-001; NCT01074047) that assessed azacitidine (AZA) vs conventional care regimens (CCR; intensive chemotherapy, low-dose cytarabine or best supportive care as preselected by the treating physician) in older patients (≥65 years) with newly diagnosed acute myeloid leukemia (AML) and 〉 30% bone marrow (BM) blasts, AZA was associated with a clinically meaningful improvement in overall survival (OS) vs CCR.1Patient registry data, if performed with adequate quality control, can complement and be of additional value to data generated in clinical trials. The Austrian Azacitidine Registry (AAR; NCT01595295) was initiated to gain a comprehensive view of the use, safety and efficacy of AZA in patients with AML in a 'real world' clinical practice setting.2,3 No formal exclusion criteria existed, as the aim was to include all AML patients treated with AZA, irrespective of age, comorbidities, and/or previous lines of treatment.2,3 Aims and methods The aim of this analysis was to assess the efficacy and safety of 1st -line AZA in patients with AML who were included in the AAR and who fulfilled the BM blast percentage and white blood cell (WBC) count entry criteria of the AML-001 trial (BM blasts 〉 30% and WBC 〈 15G/L). Outcomes of the subgroups of patients with poor-risk cytogenetics and with AML and myelodysplasia-related changes (AML-MRC) who received 1st -line AZA were also evaluated. Results A total of 95 patients were identified that fulfilled the BM blast percentage and WBC count entry criteria of the AML-001 trial (data cut-off June 19 2015). Apart from a higher proportion of AML-MRC and a lower proportion of AML-not otherwise specified (AML-NOS) within the AAR, baseline characteristics were comparable to those observed in AML-001 (i.e. age, BM blast percentage, gender, therapy-related AML, prior myelodysplastic syndrome (MDS), Eastern Cooperative Oncology Group Performance Status (ECOG PS), cytogenetic risk, transfusion dependence, hemoglobin level, WBC count, absolute neutrophil count, and platelet (PLT) count; Figure 1). Patient status at data cut-off, reasons for AZA discontinuation and treatment characteristics were also similar: median number of AZA cycles was 5 (1-51) and 6 (1-28) for the AAR and AML-001 trial, respectively (Figure 1). Patient outcome in terms of overall response according to International Working Group criteria4 (31.5 vs 29.0%), red blood cell (42.1 vs 38.5%) and PLT transfusion independence (34.5 vs 40.6%) did not differ significantly between the AAR and the AML-001 trial. Furthermore, median OS was highly concordant between the AAR and AML-001 overall (10.8 vs 10.4 months; Figure 2A) as well as for various patient subgroups: 12.2 vs 12.7 months for patients with AML-MRC (Figure 2B); 14.6 vs 14.1 months for patients with normal cytogenetics; 13.1 vs 13.0 months for patients with intermediate-risk cytogenetics; and 7.2 vs 6.4 months for patients with high-risk cytogenetics (Figure 2C). After 1 year, 47.4% of patients were still alive in the AAR cohort compared with 46.5% in the AML-001 trial (p=0.924). Event-free survival was 5.5 (range: 0-35.3) vs 6.7 (range: 5-8.8) months in the AAR and AML-001 trial, respectively. The 30-day (8.4 vs 6.6%; p=0.642) and 60-day (15.5 vs 16.2%; p=0.903) mortality rates were comparable. The incidence of febrile neutropenia (24.2 vs 28.0%) and Grade 3-4 treatment-emergent (TE) neutropenia were similar between the AAR and AML-001; however, higher rates of TE thrombocytopenia (47.4 vs 15.7%; p=0.023) and anemia (31.6 vs 26.3%; p 〈 0.001) were observed in the AAR. Conclusion These data confirm the safety and efficacy of AZA in a patient-population for whom this drug has not yet been approved, i.e. AML with more than 30% BM blasts and without leukocytosis. These data therefore complement prospective clinical trial data and support the role of well-designed and in-depth clinical registries. References 1. Dombret H, et al. Blood 2015;126:291-9 2. Pleyer L, et al. J Hematol Oncol 2013;6:32 3. Pleyer L, et al. Ann Hematol 2014;93:1825-38 4. Cheson BD, et al. J Clin Oncol 2003;21:4642-9 Disclosures Pleyer: Celgene: Consultancy, Honoraria; Bristol-Myers Squibb: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; AOP Orphan Pharmaceuticals: Honoraria. Off Label Use: Vidaza (azacitidine) is indicated for the treatment of adult AML patients who are not eligible for hematopoietic stem cell transplantation with 20-30% blasts and multi-lineage dysplasia, according to WHO classification. This cohort also includes AML patients with 〉 30% bone marrow blasts.. Burgstaller:Novartis: Honoraria; Celgene: Consultancy, Honoraria, Research Funding; AOP Orphan Pharmaceuticals: Honoraria, Research Funding; Mundipharma: Honoraria. Girschikofsky:Mundipharma: Consultancy, Honoraria; Pfizer: Honoraria, Research Funding. Sill:Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding. Thaler:AOP Orphan: Research Funding. Halter:Medical University Innsbruck: Employment. Zebisch:Celgene: Honoraria. Pichler:Celgene: Honoraria. Pfeilstöcker:Novartis: Consultancy, Speakers Bureau; Celgene: Consultancy, Honoraria, Research Funding, Speakers Bureau. Autzinger:Wilhelminenspital: Employment. Lang:Celgene: Consultancy. Geissler:Celgene: Membership on an entity's Board of Directors or advisory committees. Geissler:Klinikum Klagenfurt: Employment. Sperr:Ariad: Consultancy; Celgene: Consultancy. Hojas:LKH Fürstenfeld: Employment. Greil:Astra-Zeneca: Honoraria; Ratiopharm: Research Funding; GSK: Research Funding; Sanofi Aventis: Honoraria; Pfizer: Honoraria, Research Funding; Eisai: Honoraria; AOP Orphan: Research Funding; Novartis: Honoraria; Celgene: Consultancy; Merck: Honoraria; Cephalon: Consultancy, Honoraria, Research Funding; Bristol-Myers-Squibb: Consultancy, Honoraria; Genentech: Honoraria, Research Funding; Roche, Celgene: Honoraria, Research Funding; Amgen: Honoraria, Research Funding; Mundipharma: Honoraria, Research Funding; Janssen-Cilag: Honoraria; Boehringer-Ingelheim: Honoraria.

Abstract: Since its first identification in Scotland, over 1,000 cases of unexplained paediatric hepatitis in children have been reported worldwide, including 278 cases in the UK 1 . Here we report an investigation of 38 cases, 66 age-matched immunocompetent controls and 21 immunocompromised comparator participants, using a combination of genomic, transcriptomic, proteomic and immunohistochemical methods. We detected high levels of adeno-associated virus 2 (AAV2) DNA in the liver, blood, plasma or stool from 27 of 28 cases. We found low levels of adenovirus (HAdV) and human herpesvirus 6B (HHV-6B) in 23 of 31 and 16 of 23, respectively, of the cases tested. By contrast, AAV2 was infrequently detected and at low titre in the blood or the liver from control children with HAdV, even when profoundly immunosuppressed. AAV2, HAdV and HHV-6 phylogeny excluded the emergence of novel strains in cases. Histological analyses of explanted livers showed enrichment for T cells and B lineage cells. Proteomic comparison of liver tissue from cases and healthy controls identified increased expression of HLA class 2, immunoglobulin variable regions and complement proteins. HAdV and AAV2 proteins were not detected in the livers. Instead, we identified AAV2 DNA complexes reflecting both HAdV-mediated and HHV-6B-mediated replication. We hypothesize that high levels of abnormal AAV2 replication products aided by HAdV and, in severe cases, HHV-6B may have triggered immune-mediated hepatic disease in genetically and immunologically predisposed children.

Abstract: To assess and describe the aetiology and management of febrile illness in children with primary or acquired immunodeficiency at high risk of serious bacterial infection, as seen in emergency departments in tertiary hospitals. Prospective data on demographics, presenting features, investigations, microbiology, management, and outcome of patients within the ‘Biomarker Validation in HR patients’ database in PERFORM, were analysed. Immunocompromised children ( 〈  18 years old) presented to fifteen European hospitals in nine countries, and one Gambian hospital, with fever or suspected infection and clinical indication for blood investigations. Febrile episodes were assigned clinical phenotypes using the validated PERFORM algorithm. Logistic regression was used to assess the effect size of predictive features of proven/presumed bacterial or viral infection. A total of 599 episodes in 482 children were analysed. Seventy-eight episodes (13.0%) were definite bacterial, 67 episodes probable bacterial (11.2%), and 29 bacterial syndrome (4.8%). Fifty-five were definite viral (9.2%), 49 probable viral (8.2%), and 23 viral syndrome (3.8%). One hundred ninety were unknown bacterial or viral infections (31.7%), and 108 had inflammatory or other non-infectious causes of fever (18.1%). Predictive features of proven/presumed bacterial infection were ill appearance (OR 3.1 (95% CI 2.1–4.6)) and HIV (OR 10.4 (95% CI 2.0–54.4)). Ill appearance reduced the odds of having a proven/presumed viral infection (OR 0.5 (95% CI 0.3–0.9)). A total of 82.1% had new empirical antibiotics started on admission ( N  = 492); 94.3% proven/presumed bacterial ( N  = 164), 66.1% proven/presumed viral ( N  = 84), and 93.2% unknown bacterial or viral infections ( N  = 177). Mortality was 1.9% ( N  = 11) and 87.1% made full recovery ( N  = 522).    Conclusion : The aetiology of febrile illness in immunocompromised children is diverse. In one-third of cases, no cause for the fever will be identified. Justification for standard intravenous antibiotic treatment for every febrile immunocompromised child is debatable, yet effective. Better clinical decision-making tools and new biomarkers are needed for this population. What is Known: •  Immunosuppressed children are at high risk for morbidity and mortality of serious bacterial and viral infection, but often present with fever as only clinical symptom. •  Current diagnostic measures in this group are not specific to rule out bacterial infection, and positivity rates of microbiological cultures are low. What is New: •  Febrile illness and infectious complications remain a significant cause of mortality and morbidity in HR children, yet management is effective. •  The aetiology of febrile illness in immunocompromised children is diverse, and development of pathways for early discharge or cessation of intravenous antibiotics is debatable, and requires better clinical decision-making tools and biomarkers.