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Additional data on blast phase (BP) chronic myeloid leukaemia (CML) in children and adolescents is essential for improving diagnostic and therapeutic approaches of this rare but serious condition. Here, we describe distinct clinical and genetic characteristics of 18 paediatric patients with de novo (n = 10) and secondary (n = 8) BP CML enrolled in the CML-PAED-II trial and registry. Our findings suggest that paediatric patients exhibit a diverse cytogenetic profile compared to adults with BP CML. In addition, patients with de novo BP CML in this cohort presented at a younger age, whereas patients with secondary BP CML more often harboured complex karyotypes.

Zusammenfassung Hintergrund Die Chronische Myeloische Leukämie (CML) repräsentiert nur 2–3% der pädiatrischen Leukämien. Sie wird meist in chronischer Phase (CML-CP) diagnostiziert und schreitet unbehandelt zur akzelerierten (CML-AP) und schließlich akut lebensbedrohlichen Blastenphase (CML-BP) fort. Anders als bei anderen Leukämieformen erfolgt in CML-CP keine intensive Chemotherapie, sondern auf unbestimmte Dauer eine Therapie mit oralen Medikamenten, den Tyrosinkinase-Inhibitoren (TKI). Diese kann mit allgemeinen und entwicklungsspezifischen Nebenwirkungen assoziiert sein. Die Seltenheit der pädiatrischen CML limitiert die Erfahrung bei der Festlegung des Grades der Behinderung (GdB) durch die Behörden. Methoden Es erfolgte eine Fragebogen-Erhebung zu den Abläufen bei Antragsstellung für einen Schwerbehindertenausweis. Resultate 34/70 Patienten (49%; medianes Alter 11 J, Bereich 3–17 J; CML-CP/-AP/-BP: N= 28/3/3 Patienten) beantworteten die Fragen. Die mediane TKI-Therapiedauer betrug 33 Monate (Bereich 4–163 Mon.), wobei 24/34 Patienten (71%) Nebenwirkungen berichteten. 5/34 Patienten (15%) hatten keinen Behindertenausweis beantragt. In CML-BP wurde ein GdB 100 allen und in CML-AP 2 von 3 Patienten bewilligt; dem 3. Patienten wurde GdB 60 zugestanden. Bei den 21 Patienten in CML-CP variierte der bewilligte GdB von 20–100; 9/28 Patienten (32%) erhielten GdB 50. Das Merkzeichen H (hilflos) wurde bei 5/28 Patienten (18%) in CML-CP bewilligt. Fazit Verglichen mit anderen pädiatrischen Malignomen lässt die große Spannbreite des GdB bei CML-CP auf eine Unsicherheit bei der Einschätzung der Einschränkungen durch die Erkrankung und Therapie schließen. Vorgaben bei Erwachsenen mit CML bieten nur wenig Orientierung, da sich bei pädiatrischen Patienten auch häufig entwicklungsspezifische Nebenwirkungen ergeben.

Background: Chronic myeloid leukaemia (CML) is a rare disease in children. The frequency and outcome of children evolving to accelerated phase (AP) or blastic phase (BP) under treatment with imatinib is unknown. The aim of the current study is to assess the inci-dence of progression from CML in chronic phase with imatinib frontline in a paediatric setting and describe the management and outcome of these patients.Patients and methods: In the I-CML-Ped Study database (www.clinicaltrials.gov, #NCT01281735), 19 of 339 paediatric patients in chronic phase treated with imatinib in the frontline evolved to CML-AP or CML-BP.Results: With a median follow-up of 38 months (range: 2-190 months), the cumulative inci-dence of progression at 1 and 3 years was 3% (confidence interval [CI] 95%: 1-5%) and 7% (CI 95%: 4-11%), respectively. We observed a large predominance of lymphoid-BP (70%) over myeloid-BP (30%) with imatinib in frontline therapy. Sixteen patients underwent haemato-poietic stem cell transplantation, and eight were treated with a tyrosine kinase inhibitor after transplant. Only the transplanted patients are alive. The 5-year overall survival rate of children with CML-AP/BP is 44%, with no statistical difference between the lymphoid-BP and myeloid-BP outcome.Conclusion: Children evolving to AP or BP under treatment with imatinib have a very poor prognosis with an overall survival under 50%, much worse than children with advanced phase at diagnosis. (c) 2020 Elsevier Ltd. All rights reserved.

Chronic myeloid leukemia (CML) in minors is a rare disease which can be effectively treated by tyrosine kinase inhibitors (TKIs) since the year 2000. A majority of pediatricians will encounter one or two CML patients in the course of their careers and will typically have to rely on written information along with their own intuition to provide care. Knowledge of response to TKIs and of age-specific side effects has an impact on the design of pediatric CML trials in many ways aiming to contribute toward greater predictability of clinical improvements. Information from a registry on a rare disease like CML offers the enormous benefit of enabling treating physicians to interact and share their collective experience. The International Registry on Pediatric CML (IR-PCML) was founded at Poitiers/France almost 10 years ago. Since then, the number of collaboration centers and in parallel of registered patients continuously increased (> 550 patients as of December 2019). Ideally, from a given treatment center in a country data are transferred to a national coordinator who interacts with the IR-PCML. In the sense of quality assurance, the registry can offer dissemination of knowledge on state-of-the-art diagnostics (including reference appraisal), optimal treatment approaches, and follow-up procedures within a network that is exerting its strength via participation. With continuous growth during the recent years, very rare subgroups of patients could be identified (e.g., CML diagnosed at age < 3 years, children presenting with specific problems at diagnosis or during course of treatment) which had not been described before. Publications coming from the IR-PCML disseminated this useful information derived from patients who robustly participate and share information about their disease, among themselves and with their caregivers and clinicians. Patient input driving the collection of data on this rare leukemia is the basis for the considerable success of bringing new therapeutics into clinical use.

Ponatinib has proven to be effective in adults with Philadelphia chromosome-positive leukaemias, but data in paediatrics are scarce. Among paediatric patients with chronic myeloid leukaemia (n = 9) or acute lymphoblastic leukaemia (n = 12) treated with varying doses of ponatinib in 13 centres, 71% showed a decrease in disease burden after a median of three months. Ponatinib was well tolerated, with grade 3 toxicities occurring in 29% of patients. Toxicities were similar to those reported in adults, with the exception of arterial thrombotic events, which were not observed. Ponatinib has a favourable safety profile in this paediatric cohort, but dose-finding studies are needed.

Background Isolated myelosarcoma of infancy is a rare presentation of acute myelogenous leukaemia (AML). Because of its rarity and early onset in infancy underlying genetic predisposition is potentially relevant in disease initiation. Methods and Results We report an oncologic emergency in an infant with thoracic and intraspinal aleukaemic myeloid sarcoma causing acute myelon compression and lower leg palsy. Whole‐exome sequencing of the patient's germline DNA identified a rare PALB2 (OMIM 610355) variant (p.A1079S), which is located in a domain critical for the gene's proper function within the homology‐directed repair pathway. In line with potential DNA damage repair defects mediated by the PALB2 deregulation, the patient's fibroblasts showed increased sensitivity towards radiation and DNA intercalating agents. Conclusion Therefore, we suggest PALB2 p.A1079S as a pathogenic variant potentially contributing to the here observed patient phenotype., We present the finding of an infant with thoracic and intraspinal aleukemic myeloid sarcoma with a rare germline PALB2 variant (p.A1079S). The identified variant is located in a domain critical for the gene's proper function within the homology‐directed repair pathway. A functional role of the variant is further supported by increased sensitivity towards irradiation and DNA intercalating agents observed in primary cells from the patient carrying PALB2 p.A1079S.

Acquired polyneuropathies (PN) are rare in childhood and adolescent. We report on a 15-year-old male patient who presented with progressive gait instability, ataxia, neuropathic pain, distal muscle weakness and progressive loss of ambulation. Nerve conduction studies (NCS) revealed a progressive demyelinating sensorimotor polyneuropathy predominantly of the lower limbs. Cerebrospinal fluid (CSF) analyses revealed a cytoalbuminologic dissociation. Extensive diagnostic workup for autoantibodies and inflammatory markers was inconclusive. Corticosteroids and intravenous immunoglobulins did not affect. Cranial MRI revealed leptomeningeal enhancement of the cerebellum and the brainstem. Brain biopsy of the cerebellar lesions revealed an unclassifiable sarcoma. The patient was treated according to the CWS guidance study resulting in a decrease in enhanced lesion size. After two years NCS still revealed a demyelinating sensorimotor PN. This case report describes for the first time the clinical course of a chronic PN, putative paraneoplastic, associated with isolated unclassifiable CNS-sarcoma in an adolescent patient. Paraneoplastic pathogenesis should be considered in an unusual sequence of subacute progressive neurological symptoms even in children and adolescents.

Simple Summary The low incidence (1:1,000,000) of chronic myeloid leukemia (CML) in the first two decades of life presents an obstacle to accumulation of pediatric experience and knowledge on this leukemia. Biological features of CML are shared but also differing between adult and pediatric patients. This review aims; (i) to define the disease based on an unified terminology, (ii) to list the diseases to be considered as a differential diagnosis in children, (iii) to outlines the morphological, histopathological and immuno-phenotypical findings of pediatric CML, (iv) to illustrate rare but classical complications resulting from high white cell and platelet counts at diagnosis, and (v) to recommend a uniform approach for the diagnostic procedures to be applied. Evidently, only a clear detailed picture of all relevant features can lay the basis for standardized treatment approaches. Abstract Depending on the analytical tool applied, the hallmarks of chronic myeloid leukemia (CML) are the Philadelphia Chromosome and the resulting mRNA fusion transcript BCR-ABL1. With an incidence of 1 per 1 million of children this malignancy is very rare in the first 20 years of life. This article aims to; (i) define the disease based on the WHO nomenclature, the appropriate ICD 11 code and to unify the terminology, (ii) delineate features of epidemiology, etiology, and pathophysiology that are shared, but also differing between adult and pediatric patients with CML, (iii) give a short summary on the diseases to be considered as a differential diagnosis of pediatric CML, (iv) to describe the morphological, histopathological and immunophenotypical findings of CML in pediatric patients, (v) illustrate rare but classical complications resulting from rheological problems observed at diagnosis, (vi) list essential and desirable diagnostic criteria, which hopefully in the future will help to unify the attempts when approaching this rare pediatric malignancy.

Targeted therapy by tyrosine kinase inhibitors (TKIs) has dramatically improved survival rates in CML. Today stem cell transplantation is no longer the first-line treatment also in children. However, in the majority of patients, TKIs probably have to be administered over decades to control instead of eradicating completely the malignant cell clone. Thus, CML nowadays has to be regarded in sensu stricto as “chronic” which is in sharp contrast to the other pediatric malignancies dealt with in the context of this book. Lifelong TKI administration requires assessment of any side or “late” effect as a possible “untargeted consequence of a targeted treatment,” which represents a novelty in pediatric oncology. Systematic investigations on TKI late effects in adults are missing, and the cumulative toxicity of ongoing exposure in a growing organism with regard to young and old adulthood is presently hard to be judged on.

Background Ponatinib is effective in adults with Philadelphia chromosome–positive (Ph+) leukaemias, but scant data are available regarding the use of this tyrosine kinase inhibitor in children. Aims The aim of this study isto describe the tolerance and efficacy of compassionate use of ponatinib in a paediatric cohort of patients with Ph+ leukaemias. Methods Data from 11 children with chronic myeloid leukaemia (CML) registered to the international registry of childhood chronic myeloid leukaemia and from 3 children with Ph+ acute lymphoblastic leukaemia (Ph+ ALL) treated with ponatinib were collected retrospectively. Results In 11 girls and 3 boys (median age 14 years), ponatinib was used as a second- to eighth-line treatment. Ponatinib was administered as single therapy (9 patients) or in combination with chemotherapy (8 patients). The status of the disease when ponatinib was started was as follows: CML in advanced phases (n = 8), CML in chronic phase without achievement of molecular response (n = 2) or presence of T315I mutation (n = 1) and Ph + ALL in molecular (n = 1) or marrow (n = 2) relapses. The median dose administered was 21.4 mg/m2 and median duration of ponatinib was 2.5 months. Ponatinib alone or in combination with chemotherapy administered on 16 occasions led to achievement of major molecular response in 50% of cases. Ponatinib was used as a bridge to transplant in 4 cases. Among the 9 patients treated with ponatinib alone, toxicity grade III–IV (2 patients) was exclusively haematologic. No vascular events related to ponatinib were observed. Conclusion Ponatinib may be a reasonable additional treatment option for children with Ph+ leukaemias who have failed several lines of therapy.

INTRODUCTION Chronic myeloid leukemia (CML) is rare in the first two decades of life comprising only 3% of newly diagnosed pediatric and adolescent leukemias. We studied the epidemiologic and clinical features of patients with CML diagnosed at younger than 3 years of age and evaluated treatment and long-term outcome. METHOD Data from the International Pediatric I-BFM/CML Registry were retrospectively analyzed using the European LeukemiaNet criteria of the year 2006. Characteristics and treatment outcome of patients

ZusammenfassungKrebserkrankungen bei Kindern und Jugendlichen unter 18 Jahren sind selten; im Jahr 2017 wurden ca. 2220 Neuerkrankungen in Deutschland an das Deutsche Kinderkrebsregister gemeldet. Ziel der GPOH war es immer, möglichst alle betroffenen Patienten standardisiert, am besten in prospektiven, kontrollierten Studien, zu behandeln. Diese Vorgabe hat auch der Gemeinsame Bundesausschuss in der Kinderonkologierichtlinie festgeschrieben. In einer Umfrage unter den Studienleitern der GPOH wurde ermittelt, wie sich nach der geänderten Arzneimittelgesetzgebung, die Zahl der klinischen Studien verändert hat. Im Jahr 2002 waren 33 Therapieoptimierungs-studien (TOS) der GPOH geöffnet. Insgesamt ist ein Rückgang der TOS von 33 im Jahre 2002 auf 2 im Jahre 2017 zu verzeichnen. Die Zahl der Arzneimittelstudien hat sich bis zum Jahr 2017 auf 16 erhöht (knapp 1100 erfasste Patienten). Zeitgleich hat sich die Zahl der klinischen Register auf 28 erhöht mit insgesamt mehr als 1800 dort erfassten Patienten. Diese Beobachtung zeigt, dass die klinischen Register eine neue Bedeutung in der pädiatrischen Onkologie bekommen haben. An 3 Beispielen wird dargelegt, welche Beiträge Register im Verhältnis zu Studien zur Behandlung der Patienten und zum wissenschaftlichen Fortschritt leisten können. Zusammengefasst verdeutlichen die bisherigen Erfahrungen aus den diskutierten Beispielen, dass Studien und Register wechselseitig eine sinnvolle und notwendige Ergänzung der Studiengruppenstruktur in der Kinderonkologie darstellen.

Introduction: CML is a rare disease in children and adolescents, accounting for 2-3% of leukemia cases in this population. Pediatric CML is more frequent in the 2 nd decade of life but data on adolescents are limited. Only response to treatment has been analyzed in few studies and seems to be poorer in this age cohort. The International Registry of Childhood Chronic Myeloid Leukemia gave us the opportunity to analyze the characteristics and outcome in a large cohort of adolescents. Aims and objectives: To report on clinical features and response to treatment in adolescents (15-18 years of age at diagnosis) with CML in chronic phase (CML-CP). Material and methods: The International Registry of Childhood CML (I-CML-Ped Study, registered at www.clinicaltrials.gov NCT01281735) enrolled patients less than 18 years of age at diagnosis of CML in all phases according to the criteria of the European Leukemia Net (ELN). Data from this registry collected from Jan 2011 - Mar 2021 into the I-CML-Ped Study (Poitiers, France) were retrospectively analyzed. Results: Out of 614 patients (pts) registered in the I-CML-Ped Study, we identified 144 (23.4%) adolescents (15-18 years of age at diagnosis) with sufficient available data. Among them, according to the ELN criteria, 132 (92%), 7 (5%), and 5 (3%) pts presented with CML-CP, accelerated phase (AP), and blastic phase (BP), respectively. The median age of the cohort comprising 132 adolescents with CML-CP was 16.2 years [range, 15-18]. Ratio male/female was 1.75. Splenomegaly was reported in 66% of the pts with a median spleen size of 11.5 cm below the costal margin [range, 1-32]. Hepatomegaly was reported in 31% of the pts with a median liver size of 2.5 cm below the costal margin [range, 1-19]. Pain, asthenia and weight loss were the most frequent symptoms at diagnosis in 35%, 33%, and 20% of pts, respectively. The performance status according to the OMS and Karnofsky scores were 0 and 100% in 81% and 57% of the pts, respectively. At diagnosis, median leukocyte count was 181 G/L [range, 7-820]; median platelet count was 516 G/L [range, 102-2619], and median hemoglobin level was 10.45 g/dL [range, 4-17]. BCR-ABL1 transcript type b3a2 was present in 53% of the assessable pts. Additional chromosomal abnormalities and variants were found in 5% of the pts. 9% and 40% of pts were considered at high-risk according to the ELTS score and to the Sokal score (for pts less than 45 years), respectively. The majority of pts (97%) were treated with imatinib as first line treatment. After 12 months of treatment, in pts with data available, rate of complete cytogenetic response (CCyR) was 74/109 (68%) pts with imatinib first line. Overall, rate of CCyR was 101/109 (93%) pts with imatinib first line [88/109 (81%) pts receiving imatinib only, 13/109 (12%) pts after switching to another TKI, 8/109 (7%) pts did not achieve CCyR]. Median time to achieve CCyR was 8.2 months [range, 2.7-106.7]. The cumulative rate of MMR at month 12 was 40/111 (36%) pts. Overall rate of MMR was 91/111 (82%) pts [72/111 (65%) pts with first line imatinib only; 19/111 (17%) pts with another TKI]. Median time to achieve first MMR was 14.5 months [range, 0.9-63.1]. Out of all patients on first line imatinib, 11/123 (9%) pts progressed: 3/11 pts progressed to AP and 8/11 pts to BP. Further progress to BP was observed in 2 of the 3 pts with AP. BP phenotype was myeloid in 5/10 pts, lymphoid in 3/10 pts and bilineage in 1/10 pts (no data for 1/10 pts). With imatinib first line, deaths occurred in 5/123 (4%) pts, among them 4/5 due to complications associated with hematopoietic stem cell transplantation. With a median follow up of 37 months [range, 0.9-231], the overall survival rate was 89.2% [83.6%; 94.7%] for pts treated with imatinib first line (N = 123). Conclusion: Our results are in line with publications describing adolescents and young adults (AYAs) as a risk population for a poorer treatment outcome: when comparing AYAs (15-29 yrs) to adults (>30 yrs), CCyR and MMR were inferior in AYAs (cumulative CCyR 84% vs 93%, cumulative MMR 75% vs 86%, respectively) [Pemmaraju N et al., Haematologica 2012] and rates of progression to AP and BP were 8.7% in AYAs (16-29 yrs) but only 5.3% and 6.1% in adults (45-59 yrs and >60 yrs, respectively) [Kalmanti L et al. , Ann Hematol. 2013]. Additional research is required in adolescents with CML to shed light on the cause(s) for the observed differences and to further improve the outcome. Disclosures No relevant conflicts of interest to declare.

Children with CML need TKI treatment for many years, and the lack of knowledge about immune dysfunction with TKI has hindered routine immunizations. This review attempts to provide an overview of the effects of TKIs licensed for children (e.g., imatinib, dasatinib, and nilotinib) on immune function, as well as its implications on immunizations. We discuss surveillance strategies (e.g., immunoglobulin blood serum levels and hepatitis B reactivation) and immunizations. All inactivated vaccines (e.g., influenza, pneumococcal, and streptococcal) can be given during the treatment of CML in the chronic phase, although their efficacy may be lower. As shown in single cases of children and adults with CML, live vaccines (e.g., varicella, measles, mumps, rubella, and yellow fever) may be administered under defined circumstances with great precautions. We also highlight important aspects of COVID-19 in this patient population (e.g., the outcome of COVID-19 infection in adults with CML and in children with varying hemato-oncological diseases) and discuss the highly dynamic field of presently available different vaccination options. In conclusion, TKI treatment for CML causes humoral and cellular immune dysfunction, which is mild in most patients, and thus infectious complications are rare. Routine immunizations are important for health maintenance of children, but vaccinations for children with CML on TKI therapy should be carefully considered.

Within the International Registry of Childhood Chronic Myeloid Leukemia (CML), we identified 18 patients less than 18 years old at diagnosis of CML who were in the chronic phase and exhibiting a sustained deep molecular response (DMR) to imatinib defined as BCR-ABL1/ABL1 &lt, 0.01% (MR4) for at least two years followed by discontinuation of imatinib. Before discontinuation, the median duration of imatinib was 73.2 months (range, 32–109) and the median duration of MR4 was 46.2 months (range, 23.9–98.6). Seven patients experienced loss of major molecular response (MMR) 4.1 months (range, 1.9–6.4) after stopping and so restarted imatinib. The median molecular follow-up after discontinuation was 51 months (range, 6–100) for the nine patients without molecular relapse. The molecular free remission rate was 61% (95% CI, 38–83%), 56% (95% CI, 33–79%) and 56% (95% CI, 33–79%) at 6, 12 and 36 months, respectively. Six of the seven children who experienced molecular relapse after discontinuation regained DMR (median, 4.7 months, range, 2.5–18) after restarting imatinib. No withdrawal syndrome was observed. In univariate analysis, age, sex, Sokal and ELTS scores, imatinib treatment and DMR durations before discontinuation had no influence on treatment free remission. These data suggest that imatinib can be safely discontinued in children with sustained MR4 for at least two years.

Background In the adult population with newly diagnosed chronic myeloid leukemia (CML), variant translocations are usually not considered to be impairing the prognosis, whereas some additional cytogenetic abnormalities (ACAs) are associated with a negative impact on survival. Because of the rarity of CML in the pediatric population, such abnormalities have not been investigated in a large group of children with CML. Methods The prognostic relevance of variant t(9;22) and ACAs at diagnosis was assessed in 301 children with CML in the chronic phase who were enrolled in the International Registry for Chronic Myeloid Leukemia in Children and Adolescents. Results Overall, 19 children (6.3%) presented with additional cytogenetic findings at diagnosis: 5 children (1.7%) had a variant t(9;22) translocation, 13 children (4.3%) had ACAs, and 1 had both. At 3 years, for children with a classic translocation, children with ACAs, and children with a variant t(9;22) translocation who were treated with imatinib as frontline therapy, the probability of progression-free survival (PFS) was 95% (95% confidence interval [CI], 91%-97%), 100%, and 75% (95% CI, 13%-96%), respectively, and the probability of overall survival (OS) was 98% (95% CI, 95%-100%), 100% (95% CI, 43%-98%), and 75% (95% CI, 13%-96%), respectively. No statistical difference was observed between the patients with classic cytogenetic findings and those with additional chromosomal abnormalities in terms of PFS and OS. Conclusions In contrast to adults with CML, additional chromosomal abnormalities observed at diagnosis do not seem to have a significant prognostic impact. Cancer 2017;123:3609-16. © 2017 American Cancer Society.

Background: Imatinib, a tyrosine kinase inhibitor (TKI) is currently proposed as first line therapy in children with chronic myeloid leukemia (CML) in chronic phase (CP). Studies in adults with CML demonstrated that 40 to 50% of patients with prolonged deep molecular response under TKI could discontinue TKI permanently without molecular relapse. However, data regarding TKI discontinuation in children with CML are limited. Methods: Using the ELN criteria we identified in the International Registry of Childhood Chronic Myeloid Leukemia 18 patients less than 18 years of age at diagnosis with CML in CP exhibiting under imatinib treatment sustained deep molecular response >MR4.0 (DMR) for ≥ 2 years and then discontinued the TKI. We retrospectively analyzed outcome of these patients and treatment-free remission rate (TFR) at various time points. Treatment with imatinib was resumed in case of molecular relapse defined as loss of major molecular response (MMR). Results: There were 11 boys and 7 girls. From diagnosis in CP until TKI discontinuation the 18 children showed no progression, resistance, warning or suboptimal response or switch to another TKI before discontinuation. Median age at diagnosis of CML was 11.9 years (range, 2.3 to 15.8 years) and median age at discontinuation of TKI was 16 years (range, 9 to 24 years). Median overall follow-up from diagnosis of CML was 107 months (range, 67-209 months). DMR was achieved after a median time of 12 months (range, 3 - 50 months) on imatinib. Before discontinuation median treatment duration of imatinib was 73.25 months (range, 32 to 109 months) and median duration of MR4.0 was 46.2 months (range, 23.9 to 98.6 months). Seven patients experienced molecular relapse 4.1 months (range, 1.9-6.4 months) after stopping and restarted imatinib. Two patient resumed imatinib 3.6 and 3.4 months after discontinuation because of increased in transcript level (from 0.001% to 0.01 and 0.012, respectively) but without loss of MMR. The median molecular follow up after discontinuation was 116 months (range, 71 to 209 months) for the patients without molecular relapse. The proportion of patients maintaining molecular free remission was 61% (95% CI, 38%-83%), 56% (95% CI, 33%-79%) and 56% (95% CI, 33%-79%) at 6, 12, and 36 months, respectively (Figure 1). Six of the 7 children who experienced molecular relapse after discontinuation again achieved MR4.0 at median of 4.7 months (range, 2.5-18 months) after restart of imatinib; the remaining patient achieved MMR but not DMR and was switched to Dasatinib. No withdrawal syndrome was observed in this cohort of 18 patients. In univariate analysis, age, sex, Sokal and ELTS scores, imatinib treatment duration before discontinuation and duration of DMR until imatinib discontinuation had no influence on treatment free remission. Conclusion: These data indicate that imatinib could be safely discontinued in children younger than 18 years of age at diagnosis of CML with sustained MR4.0 for at least 2 years under imatinib. Larger studies of TKI discontinuation in children with CML are needed in order to identify factors predicting treatment free remission. Disclosures Dalle: Incyte: Consultancy, Membership on an entity's Board of Directors or advisory committees; Medac: Consultancy, Honoraria; Orchard: Consultancy, Honoraria; Bellicum: Consultancy, Honoraria; Jazz Pharmaceuticals: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; bluebird bio: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Sanofi-Genzyme: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Gilead: Honoraria; AbbVie Pharmacyclics: Membership on an entity's Board of Directors or advisory committees.

Chronic myeloid leukemia (CML) is a rare malignancy at younger age with less than 10% of all cases diagnosed in the first two decades of life and representing less than 2% of all pediatric leukemia...

Tyrosine kinase inhibitors (TKIs), such as imatinib (IMA) and nilotinib (NIL), are the cornerstone of chronic myeloid leukemia (CML) treatment via the blockade of the oncogenic BCR-ABL1 fusion protein. However, skeletal side effects are commonly observed in pediatric patients receiving long-term treatment with IMA. Additionally, in vitro studies have shown that IMA and NIL alter vitamin D metabolism, which may further impair bone metabolism. To determine whether TKIs directly affect bone cell function, the present study treated the human osteoblastic cell line SaOS-2 with IMA or NIL and assessed effects on their mineralization capacity as well as mRNA expression of receptor activator of nuclear factor κB ligand (RANKL) and osteoprotegerin (OPG), two cytokines that regulate osteoclastogenesis. Both TKIs significantly inhibited mineralization and downregulated osteoblast marker genes, including alkaline phosphatase, osteocalcin, osterix, as well as genes associated with the pro-osteogenic Wnt signaling pathway; NIL was more potent than IMA. In addition, both TKIs increased the RANKL/OPG ratio, which is known to stimulate osteoclastogenesis. The present results suggested that the TKIs IMA and NIL directly inhibited osteoblast differentiation and directly promoted a pro-osteoclastogenic environment through the RANKL-OPG signaling axis. Thus, we propose that future work is required to determine whether the bone health of CML patients undergoing TKI-treatment should be routinely monitored.

A considerable proportion of patients with chronic myeloid leukaemia (CML) may present at diagnosis with high platelet counts. This may result in thrombosis or bleeding complications due to binding of von Willebrand factor (VWF) multimers to platelets. Paediatric CML is very rare and no systematic investigation on clinical complications of elevated platelets has been reported. Data on platelet count and associated haemostaseological complications were retrospectively analysed in a cohort of 156 children with CML. Fifty-one percent (81/156) patients presented with thrombocytosis (platelet count> 500 × 109 /l), and were extreme (>1 000 × 109 /l) in 23/156 (16%). There were no cases of thrombosis but mild bleeding signs were present in 12% (n = 9) children with thrombocytosis. Bleeding occurred without correlation to elevated platelet counts and was associated with reduced large VWF multimers, indicating a diagnosis of acquired von Willebrand syndrome (AVWS), which resolved after initiation of CML treatment. Patients with paediatric CML frequently exhibit high platelet counts not resulting in thrombosis. In patients with thrombocytosis mild bleeding signs due to a low percentage of large VWF multimers can be demonstrated. AVWS may be underdiagnosed in paediatric CML (Clinical-Trials.gov NCT00445822, 9 March 2007).

This international study aimed to assess the effect of imatinib discontinuation in paediatric patients with chronic myeloid leukaemia (CML) after deep molecular remission (DMR) had been achieved and maintained for at least 2 years. The primary endpoint of this analysis was the molecular relapse-free survival, estimated by the non-parametric Kaplan-Meier method. Major endpoint was the estimated rate of patients without molecular relapse at 6 months. Fourteen patients were enrolled; 4 patients maintained DMR with a follow-up of 24 (two patients), 34 and 66 months, respectively, whereas 10 patients relapsed. All molecular relapses occurred within 6 months (median 3 months, range 1-6) after imatinib discontinuation. The overall probability of maintaining DMR at 6 months was 28 center dot 6%. No parameters associated with molecular relapse could be identified. Keeping in mind the rarity of paediatric CML, which contributed to the small size of the cohort, our findings illustrate that imatinib cessation after sustained DMR is successful in only limited numbers of patients, whereas much higher rates are reported in adult patients. Further research is needed to extend the cohort of paediatric CML patients who might achieve treatment-free remission with an ideal prerequisite of predicting the occurrence of molecular relapse l after imatinib cessation.

Background Chronic myeloid leukaemia (CML) is very rare in children. The aim of the study is to report the experience within the I-CML-Ped study in children and adolescents presenting at diagnosis with advanced phase disease and to describe their characteristics and outcomes. Methods Of 479 children and adolescents enrolled in the international registry for childhood chronic myeloid leukaemia (I-CML-Ped Study; www.clinicaltrials.gov NCT01281735 ), 36 children (7.5%) presented at initial diagnosis with CML in advanced phase according to the European LeukemiaNet criteria. Results Nineteen (4%) patients were diagnosed in accelerated phase (CML-AP), and among the 17 patients (3.5%) diagnosed in blastic phase (CML-BP), 70% presented with lymphoid immunophenotype. Initial treatment of CML-AP/CML-BP consisted of tyrosine kinase inhibitors (TKIs) with or without chemotherapy, leading to complete haematologic response in 33 of 36 (92%) patients. Seventeen patients proceeded to haematopoietic stem cell transplantation. At the last follow-up, 18 of 19 patients with de novo CML-AP are alive in at least major molecular response (MMR) (n = 16), in progression (n = 1) or in molecular relapse (n = 1) and 13 of 17 patients with de novo CML-BP are alive in at least MMR. Five-year overall survival rates are 94% (95% confidence interval [CI]: 66%–99%) and 74% (95% CI: 44%–89%) for patients diagnosed in CML-AP and CML-BP, respectively. Conclusion Children with advanced phase at diagnosis of CML seem to have a better survival rate than that reported for advanced phases evolving under TKI treatment.

Patients with primary immunodeficiencies caused by severe defects in T cell immunity are at risk of acquiring life-threatening infections. Cellular therapies are necessary to establish normal T cell function and to allow for long-term survival. This is most commonly achieved by hematopoietic stem cell transplantation (HSCT), but the outcome of this procedure is impaired if active infections are present at the time of HSCT. Donor lymphocyte infusions (DLIs) are a well-established therapeutic strategy following HSCT to treat viral infections, improve donor cell engraftment, or achieve graft-versus-leukemia activity in malignant disease. Here we present a cohort of 6 patients with primary T cell deficiencies who received transfusions of unselected mature donor lymphocytes prior and not directly related to allogeneic HSCT. DLIs obtained from the peripheral blood of HLA-identical (10/10) family donors were transfused without prior conditioning to treat or prevent life-threatening infections. All patients are alive with a follow-up of 0.5 to 16.5 years after the initial T cell administration. Additional cellular therapies were administered in 5 of 6 patients at 0.8 to 15 months after the first DLI. Mild cutaneous graft-versus-host disease (GVHD, stage ≤2) was observed in 3 of 6 patients and resolved spontaneously. We provide evidence that unselected HLA-identical DLIs can effectively prevent or contribute to overcome infections with a limited risk for GVHD in T cell deficient patients. The T cell system established by this readily available source can provide T cell function for years and can serve as a bridge to additional cellular therapies or, in specific conditions, as definite treatment.

Hintergrund Leukamie ist die haufigste bosartige Erkrankung im Kindesalter. Es werden akute und chronische Leukamien lymphatischen oder myeloischen Ursprungs unterschieden.

Side effects of tyrosine kinase inhibitor (TKI) treatment vary in children and adults with chronic myelogenous leukemia (CML). As children have a much longer life expectancy than adults, TKI therapy may continue for decades and with long-term consequences that differ from adults. Children may develop endocrinopathies related to "off-target" effects of TKIs, such as delayed growth, changes in bone metabolism, thyroid abnormalities, and effects on puberty and fertility. These endocrinopathies present additional challenges for pediatric patients with CML. This review critically evaluates the literature on long-term endocrine side effects of TKIs in the pediatric CML population and provides suggested recommendations.

Antineoplastic treatment of osteoblastic osteosarcoma in a patient with cystic fibrosis (CF) may harbor a high risk of neutropenia-associated complications, and, to the best of our knowledge, has not been previously reported. Diagnosis of CF was confirmed in a 6-week-old boy following pathological newborn screening. The patient had a stable course of CF under standardized continuous therapy. At the age of 5 years, osteosarcoma of the left proximal humerus was diagnosed without evidence of metastases. Neoadjuvant chemotherapy, including doxorubicin, cisplatin and methotrexate, was administered for 10 weeks. The patient tolerated this therapy relatively well, with a continuous antibiotic prophylaxis of cefuroxime without experiencing major complications; in particular, no pulmonary exacerbations were observed as a consequence of immunosuppression or mucosal toxicity. The tumor responded well, and amputation of the limb was avoided via the use of 'clavicle per humerus' osteosynthesis. Postoperatively, compartmental syndrome occurred, requiring management by fasciotomy. Adjuvant chemotherapy was applied thereafter again, without major toxicity that would have required dose reduction. Under intensive physiotherapy, the mobility of the left arm and hand was deemed to be satisfactory. The coincidence of CF with osteosarcoma is extremely rare, and, to the best of our knowledge, has not been previously described. Under antibiotic prophylaxis, antineoplastic treatment was possible without major complications during neutropenia.

Evidence-based recommendations have been established for treatment of chronic myeloid leukemia (CML) in adults treated with tyrosine kinase inhibitors (TKIs), but the rarity of this leukemia in children and adolescents makes it challenging to develop similar recommendations in pediatrics. In addition to imatinib, which was approved for pediatric CML in 2003, the second-generation TKIs dasatinib and nilotinib were recently approved for use in children, expanding the therapeutic options and pushing allogeneic stem cell transplantation to a third-line treatment of most pediatric cases. Yet, without sufficient data on efficacy and safety specific to pediatric patients, the selection of a TKI continues to rely on clinical experience in adults. Here, we present 4 case scenarios highlighting common yet challenging issues encountered in the treatment of pediatric CML (suboptimal response, poor treatment adherence, growth retardation, and presentation in advanced phases). Limited experience with very young children, the transition of teenagers to adult medicine, and the goal of achieving treatment-free remission for this rare leukemia are additional significant obstacles that require further clinical investigation through international collaboration.

Background/aim DNA methylation plays an important role in the initiation and propagation of carcinogenesis; however, the role of heterogeneously methylated epialleles is currently not well studied, also due to the lack of sensitive, unbiased and high throughput methods. Here, a newly developed droplet digital PCR (ddPCR)-based method was evaluated regarding its ability to quantify such heterogeneously methylated epialleles with sufficient analytical sensitivity and specificity. Materials and methods Genomic DNA from blood leukocytes and bone marrow aspirate of an 8-year old male with B-cell acute lymphoblastic leukemia (B-ALL) and from normal and malignant prostate cell lines were analysed using ddPCR. Results By using these DNA samples, the specificity of an applied set of fluorescence-labeled probes was demonstrated as a proof of concept. Conclusion All individual heterogeneously-methylated epialleles were quantifiable by a set of fluorescence-labeled probes with complementary sequences to epialleles in a closed-tube and high-throughput manner. The new method named epiallele-sensitive droplet digital PCR (EAST-ddPCR) may give new insights in the generation and regulation of epialleles and may help in finding new biomarkers for the diagnosis of benign und malignant diseases.

Osteonecrosis (ON) was prospectively assessed in 557 children and adolescents in the Berlin-Frankfurt-Münster Stem Cell Transplantation in children with acute lymphoblastic leukaemia 2003 trial. Median age at haematopoietic stem cell transplantation (HSCT) was 10·3 years (range 0·5-26). Cumulative incidence of symptomatic ON (sON) was 9% at 5 years (standard deviation 1%), median time from HSCT to diagnosis of sON was 12·4 months (range 1-126). Multivariate analysis identified age at HSCT [10-15 years vs.10 years: hazard ratio (HR) 3·73, P = 0·009;15 years vs.10 years: HR 5·46, P = 0·001], diagnosis of sON prior to HSCT and chronic graft-versus-host disease (yes versus no: HR 2·696, P = 0·015) as significant independent risk factors for the development of sON.

Burkitt lymphoma (BL) in children often presents with abdominal localization. Intestinal perforations have been described mainly during treatment. We report on a three-year-old patient with abdominal BL who was diagnosed with a duodenocolonic fistula.A three-year-old boy presented with diarrhea, crampy abdominal pain, and a four-week history of loss of appetite and weight. Ultrasound and MRI detected a colonic tumor forming a duodenocolonic fistula which was verified by gastroduodenoscopy. A surgical biopsy revealed BL. The stage III BL with low LDH was treated with four courses of BFM-type short-pulse chemotherapy. After two courses of chemotherapy the patient developed a mechanic ileus. A segmental resection of a short segment of the colon at the right flexure carrying the residual tumor mass with cicatricial stenosis and fistula followed by colonic end to end anastomosis and covering of the fistula by omentum major were carried out without complication. 15 days after surgery, two additional courses of chemotherapy could be administrated and the boy is in ongoing remission and free of any symptoms with a follow-up interval of 18 months.Duodeonocolonic fistula at presentation in a child with abdominal BL is extremely rare. Delayed surgery after size of the tumor bulk has been reduced by chemotherapy might represent a risk adapted approach. However, due to limited experience with duodenocolonic fistulas even in larger pediatric lymphoma trials any decision has to be based on the problems to be faced in individual cases.Ein Burkitt-Lymphom (BL) im Kindesalter ist oft im Abdomen lokalisiert. Intestinale Perforationen wurden in der Literatur zumeist als während der Chemotherapie auftretende Komplikation beschrieben. Wir berichten über einen Patienten mit abdominellen BL, welcher bei Diagnosestellung eine duodenokolische Fistel aufwies.Ein 3jähriger Junge wurde vorgestellt mit rezidivierenden Diarrhoen, krampfartigen Bauchschmerzen, Appetitlosigkeit und Gewichtsverlust über einen 4wöchigen Zeitraum. Die radiologische Diagnostik mittels Abdomensonographie und MRT ergab das Bild eines Tumors, welcher eine duodenokolonische Fistel ausgebildet hatte, was mittels Ösophagogastroduodenoskopie bestätigt wurde. Die chirurgische Tumorbiopsie sicherte den Befund eines BL. Es handelte sich um das Stadium III mit einer leichten LDH-Erhöhung. Nach 2 Blöcken der Chemotherapie entwickelte der Patient einen mechanischen Ileus. Eine operative kurzstreckige Segementresektion des stenosierenden und fistelbildenden Tumors im Bereich des Colons ascendens wurde mit einer End-zu-End-Anastomose und Abdecken der Fistel durch Omentum majum ohne Komplikationen durchgeführt. Am 15. postoperativen Tag konnten anschließend 2 weitere Chemotherapie-Blöcke verabreicht werden. Der Patient befindet sich 16 Monaten später beschwerdefrei in Remission.Eine duodenokolonische Fistel als Komplikation eines abdominellen BL ist eine extreme Rarität. Die verzögerte Resektion nach Tumorverkleinerung durch Chemotherapie stellt möglicherweise eine risiko-adaptierte Vorgehensweise dar. Jedoch sollte jede Entscheidung zur Vorgehensweise bei duodenokolonischen Fisteln aufgrund der fehlenden Erfahrungen im Kindesalter auch innerhalb großer Lymphomstudien immer individuell angepasst sein.

A total of 156 patients (age range 1.3-18.0 years, median 13.2 years; 91 (58.3%) male) with newly diagnosed CML (N = 146 chronic phase (CML-CP), N = 3 accelerated phase (CML-AP), N = 7 blastic phase (CML-BP)) received imatinib up-front (300, 400, 500 mg/m 2 , respectively) within a prospective phase III trial. Therapy response, progression-free survival, causes of treatment failure, and side effects were analyzed in 148 children and adolescents with complete data. Event-free survival rate by 18 months for patients in CML-CP (median follow-up time 25 months, range: 1-120) was 97% (95% CI, 94.2-99.9%). According to the 2006 ELN-criteria complete hematologic response by month 3, complete cytogenetic response (CCyR) by month 12, and major molecular response (MMR) by month 18 were achieved in 98, 63, and 59% of the patients, respectively. By month 36, 86% of the patients achieved CCyR and 74% achieved MMR. Thirty-eight patients (27%) experienced imatinib failure because of unsatisfactory response or intolerance (N = 9). In all, 28/148 patients (19%) underwent stem cell transplantation (SCT). In the SCT sub-cohort 2/23 patients diagnosed in CML-CP, 0/1 in CML-AP, and 2/4 in CML-BP, respectively, died of relapse (N = 3) or SCT-related complications (N = 2). This large pediatric trial extends and confirms data from smaller series that first-line imatinib in children is highly effective.

Blood is arguably the most important bodily fluid and its analysis provides crucial health status information. A first routine measure to narrow down diagnosis in clinical practice is the differential blood count, determining the frequency of all major blood cells. What is lacking to advance initial blood diagnostics is an unbiased and quick functional assessment of blood that can narrow down the diagnosis and generate specific hypotheses. To address this need, we introduce the continuous, cell-by-cell morpho-rheological (MORE) analysis of diluted whole blood, without labeling, enrichment or separation, at rates of 1000 cells/sec. In a drop of blood we can identify all major blood cells and characterize their pathological changes in several disease conditions in vitro and in patient samples. This approach takes previous results of mechanical studies on specifically isolated blood cells to the level of application directly in blood and adds a functional dimension to conventional blood analysis., eLife digest When you are sick and go to the doctor, it is often not obvious what exactly is wrong — what is causing fever, nausea, shortness of breath or other symptoms. It is important to find this out quickly so that the right action can be taken. One of the first steps is to obtain a blood sample and to count how many of the different blood cells are present in it. This is called a complete blood count, and the information it provides has turned out to be surprisingly useful. A large number of certain white blood cells, for example, can show that the body is fighting an infection. But there might be several reasons why the number of white blood cells has increased, so this information alone is often not enough for a specific diagnosis. There are many hundreds of possible tests that can supplement the results of a complete blood count. These might identify bacteria or measure the concentrations of certain molecules in the blood, for example. But which test will give the important clue that reveals the source of the illness? This can be difficult to predict. Although each test helps to narrow down the final diagnosis they become increasingly expensive and time-consuming to perform, and rapid action is often important when treating a disease. Can we get more decisive information from the initial blood test by measuring other properties of the blood cells? Toepfner et al. now show that this is possible using a technique called real-time deformability cytometry. This method forces the blood cells in a small drop of blood to flow extremely rapidly through a narrow microfluidic channel while they are imaged by a fast camera. A computer algorithm can then analyze the size and stiffness of the blood cells in real-time. Toepfner et al. show that this approach can detect characteristic changes that affect blood cells as a result of malaria, spherocytosis, bacterial and viral infections, and leukemia. Furthermore, many thousands of blood cells can be measured in a few minutes — fast enough to be suitable as a diagnostic test. These proof-of-concept findings can now be used to develop actual diagnostic tests for a wide range of blood-related diseases. The approach could also be used to test which of several drugs is working to treat a certain medical condition, and to monitor whether the treatment is progressing as planned.

Here we report on a child with Li-Fraumeni syndrome with a de novo TP53 mutation c.818G>A, who developed three malignancies at the age of 4 months, 4 and 5 years, respectively. We show that (i) in the choroid plexus carcinoma, the germline mutation was detected in a homozygous state due to copy-neutral LOH/uniparental disomy, (ii) in the secondary AML, a complex karyotype led to loss of the wild-type TP53 allele, (iii) in the Wilms tumor, the somatic mutation c.814G>A led to compound heterozygosity. The findings show that the complete inactivation of TP53 by different mechanisms is an important step towards tumorigenesis.

Chronic myeloid leukemia (CML) is a myeloproliferative disease characterized by the presence of the BCR‑ABL1 fusion gene, a constitutively active, oncogenic tyrosine kinase that is responsible for the clinical features of CML. Tyrosine kinase inhibitors, such as imatinib, have markedly altered the treatment of CML. However, tyrosine kinase inhibitors are associated with side effects on bone metabolism, in adult and pediatric patients. Vitamin D3 is involved in the complex cycle of bone remodeling, therefore the present study aimed to investigate the influence of imatinib on vitamin D3 metabolism in the HaCaT human keratinocyte cell line, using commercially available enzyme assays. Imatinib was shown to significantly reduce the production of calcidiol and calcitriol. Based on interaction studies of imatinib with the cytochrome P450 (CYP450) inhibitors VID400 and ketoconazole, it is proposed that imatinib may interfere with the vitamin D3 cascade due to its metabolism by CYP27B1, which is involved in vitamin D3 metabolism.

Objectives: Chronic recurrent multifocal osteomyelitis (CRMO), the most severe form of chronic nonbacterial osteomyelitis (CNO), is an autoinflammatory bone disorder. In the absence of diagnostic criteria or biomarkers, CNO/CRMO remains a diagnosis of exclusion. The aim of this study was to identify biomarkers for diagnosing multifocal disease (CRMO). Study design: Sera from 71 pediatric CRMO patients, 11 patients with osteoarticular infections, 62 patients with juvenile idiopathic arthritis (JIA), 7 patients with para-infectious or reactive arthritis, and 43 patients with acute leukemia or lymphoma, as well as 59 healthy individuals were collected. Multiplex analysis of 18 inflammation- and/or bone remodeling-associated serum proteins was performed. Statistical analysis included univariate ANOVA, discriminant analysis, univariate receiver operating characteristic (ROC) analysis, and logistic regression analyses. Results: For 14 of 18 blood serum proteins, significant differences were determined between CRMO patients, at least one alternative diagnosis, or healthy controls. Multi-component discriminant analysis delivered five biomarkers (IL-6, CCL11/eotaxin, CCL5/RANTES, collagen Iα, sIL-2R) for the diagnosis of CRMO. ROC analysis allowed further reduction to a core set of 2 biomarkers (CCL11/eotaxin, IL-6) that are sufficient to discern between CRMO, healthy controls, and alternative diagnoses. Conclusion: Serum biomarkers CCL11/eotaxin and IL-6 differentiate between patients with CRMO, healthy controls, and alternative diagnoses (leukemia and lymphoma, osteoarticular infections, para-infectious arthritis, and JIA). Easily accessible biomarkers may aid in diagnosing CRMO. Further studies testing biomarkers in larger unrelated cohorts are warranted.

Prolonged treatment with tyrosine kinase inhibitors (TKI) including imatinib (IMA) or nilotinib (NIL), induces severe disturbances of bone metabolism in patients with chronic myeloid leukaemia. As vitamin D3 (VD3) is involved in the complex cycle of bone remodelling, the present study investigated in vitro, the influence of IMA and NIL on VD3 metabolism i) in HaCaT cells and ii) in cultured outer root sheath keratinocytes (ORS‑KC) from hair follicles of IMA treated children. Cells were incubated in the presence of IMA or NIL. Concomitantly, specific inhibitors were applied to analyze the inhibition of the VD3 processing cytochrome P450 isoenzyme family by TKIs. In vitro, IMA and NIL significantly impaired the production of calcitriol in HaCaT and cultured ORS‑KC cells from hair follicles of IMA treated children. For NIL, this inhibitory effect demonstrated a 4‑fold increase. In HaCaT and ORS‑KC, application of specific CYP450 inhibitors revealed that CYP27B1 was impaired by IMA and NIL leading to an intracellular accumulation of calcidiol. However, during TKI treatment, KC of IMA treated children revealed no differences in calcidiol and calcitriol levels. In conclusion, IMA and NIL interfere with the vitamin D3 cascade due to their metabolism by CYP27B1.

Blood is arguably the most important bodily fluid and its analysis provides crucial health status information. A first routine measure to narrow down diagnosis in clinical practice is the differential blood count, determining the frequency of all major blood cells. What is lacking to advance initial blood diagnostics is an unbiased and quick functional assessment of blood that can narrow down the diagnosis and generate specific hypotheses. To address this need, we introduce the continuous, cell-by-cell morpho-rheological (MORE) analysis of whole blood, without labeling, enrichment or separation, at rates of 1,000 cells/sec. In a drop of blood we can identify all major blood cells and characterize their pathological changes in several disease conditions in vitro and in patient samples. This approach takes previous results of mechanical studies on specifically isolated blood cells to the level of application directly in whole blood and adds a functional dimension to conventional blood analysis.

The EUTOS Long-Term Survival score was tested in 350 children with chronic myeloid leukemia in first chronic phase treated with imatinib and registered in the International Registry for Childhood Chronic Myeloid Leukemia. With a median follow up of 3 years (range, 1 month to 6 years) progression and/or death (whichever came first) occurred in 23 patients. For the entire cohort of patients the 5-year progression-free survival rate was 92% (95% CI: 87%-94%) and the 5-year survival accounting for chronic myeloid leukemia deaths was 97% (95% CI: 94%-99%). Of the 309 patients allocated to low (n=199), intermediate (n=68) and high (n=42) risk groups by the EUTOS Long-Term Survival score, events (progression and/or death) occurred in 6.0%, 8.8% and 26.2%, respectively. Estimates of the 5-year progression-free survival rates according to these three risk groups were 96% (95% CI: 92%-98%), 88% (95% CI: 76%-95%) and 67% (95% CI: 48%-81%), respectively. Differences in progression-free survival according to these risk groups were highly significant (P

Chronic myeloid leukaemia in children and young people is a relatively rare form of leukaemia that shows increased incidence with age and some evidence suggests that the molecular basis differs from that in adults. Significant advances in targeted therapy with the development and use in children of tyrosine kinase inhibitors and the ability to monitor and understand the prognostic significance of minimal residual disease by standardized molecular techniques has shifted the management of this condition from bone marrow transplantation as the main therapeutic modality to individualized treatment for each patient based on achieving specific milestones. The physiological changes occurring during childhood, particularly those affecting growth and development and the long-term use of treatment, pose specific challenges in this age group, which we are only beginning to understand.

Background: Documented experience on vaccination while on imatinib treatment is missing in children. According to current recommendations for all age groups of immunocompromised individuals inactive vaccines can safely be administered. However, depending on the grade of immunosuppression the immune response may be reduced or missing. Live attenuated vaccines must not be administered to immunosuppressed individuals according to general recommendations. To date, very few in vivo human studies have addressed the long-term impact of imatinib on the immune function. Data from in vitro and animal studies have documented seemingly contradictory effects of imatinib, ranging from impaired antigen-specific T-cell responses to reversal of T-cell tolerance and potentiation of antitumor immune responses. In adult patients (pts) with CML treated with imatinib, the B-cell response to inactivated vaccines against pneumococcus as well as H1N1 influenza virus was impaired and associated with loss of memory B-cell subsets [de Lavallade H, et al. Haematologica 2011; Blood 2013]. Accordingly, several adult cases of reactivation of hepatitis B virus infection under imatinib have been observed [Mallet V, et al. Lancet Infect Dis. 2016]. On the other hand, no opportunistic infections or uncommon courses of an infection were observed in the so far largest pediatric CML trial while pts were on imatinib treatment [Suttorp M, et al. Leukemia 2018]. The growing anti-vaccination movement in many countries based heavily on non-rational objections to vaccinations poses a world-wide threat to public health. In Europe, the number of reported cases of measles in 2018 was triple that in 2017 and 15 times that in 2016 (Thornton J, Br Med J 2019). To what extend this scenario poses any extra risk on CML pts is completely unknown. Methods: Four pediatric pts (10, 11, 12, 14 yrs old) with complete or partially non-protective titers against measles, mumps, rubella, and/or varicella were vaccinated after informed consent following individual assessments of risk and benefits once stable remission of CML had been achieved. Commercially available vaccines (M-M-RVAX Pro®, Varivax®, Priorix-Tetra®) were administered at lymphocyte counts >1500/µl. Details are listed in the table. Pt #4 was vaccinated 1 week after interruption of imatinib treatment followed by a 2 week cessation while the other 3 pts were vaccinated under ongoing imatinib treatment. Results: All seven live virus vaccinations in the 4 pts were well tolerated and no acute or late adverse events were observed (see table). Seroconversion could be confirmed in pts #1 and #3, while in pt #2 the first vaccination against measles, mumps, and rubella performed 11 months after diagnosis of CML was unsuccessful. However, revaccination three years later resulted in seroconversion. Interestingly, vaccination of this girl against varicella in the 54th month of imatinib treatment resulted in no measurable VZ-IgG in serum. Pt #4 lost his protective measles titer 7 months after vaccination when the imatinib dose was weight-adapted and increased but responded with protective titers to revaccination. Discussion: As a word of caution no sound conclusions can be drawn from this small series of only 7 vaccinations in 4 pts. Noteworthy, no adverse events resulting from attenuated live viral vaccines were observed in this cohort. The initial non-response in pt #2 when vaccinated 11 months after diagnosis of CML cannot be explained. A missing detection of varicella zoster IgG is observed in 1-5 % of healthy vaccinees and is caused by acquired T-cellular immunity against varicella (not investigated in this case). An alternative approach to be explored for administering live virus vaccination is short interruptions of imatinib treatment (2-3 weeks "off" the drug once molecular remission is achieved, pt #4). As long as herd immunity against dangerous diseases like measles is not established in many countries, pts with CML require protection. In order to accumulate knowledge we suggest that any experience with live virus vaccines in children with CML should be documented in an international registry. Disclosures No relevant conflicts of interest to declare.

Background: At diagnosis of chronic myeloid leukemia (CML) patients (pats) may present with elevated platelets (PLT) counts. Generally, high PLT counts may result in thrombosis and/or bleeding complications, the latter being due to binding of von Willebrand factor (VWF) multimers to platelets. Pediatric CML is very rare (Hijiya N, Suttorp M 2019; Blood 33:2374-2384) and no systematic investigation on clinical complications of elevated PLT counts has so far been reported. Methods: Data on PLT counts and associated thrombo-hemorrhagic complications were retrospectively analyzed in newly diagnosed pediatric pats (0 - 18 yrs old) with CML in chronic phase. Data were pooled from a German pediatric trial (CML-paed II, N= 146 pats; registered as NCT00445822, [Suttorp M, et al. 2018; Leukemia 32:1657-1669], data collection closed Dec 2016) and the International registry for CML in children and adolescents (I-CML- Ped Study, N= 475 pats, registered as NCT01281735, [Millot F, et al. 2017; Haematologica 102:1704-1708], data collection closed June 2019). Results: A total of 621 pediatric pats with CML in chronic phase could be analyzed. At diagnosis 343/621 (55.2%) pats (median age 13.2 yrs, range 1.3 - 18 yrs) presented with thrombocytosis (>500 000 PLT/µl). PLT ranged from 500 000 - 1 000 000 PLT/µl in 239/621 (38.5%) pats while extremely high PLT counts (>1 000 000 PLT /µl) were present in 94/621 (11.2%) pats. Thrombosis was observed in 2/621 (0.3%) pats including priapism occurring at 655 000 PLT/µl and lower leg venous thrombosis at 1 820 000 PLT/µl. Bleeding signs (bruises, mucosal hemorrhage) being of mild nature (grade 1, grade 2, National Cancer Institute Common Terminology Criteria v3.0) only were described in 38/343 (11.1%) pats with thrombocytosis (>500 000 PLT/µl). Bleeding occurred without correlation to elevated PLT counts but was associated in selected cases investigated with a reduced plasma concentration of large VWF multimers pointing to the diagnosis of acquired von Willebrand syndrome (AVWS). AVWS resolved after initiation of CML treatment with imatinib. Discussion: In newly diagnosed pediatric pats with CML, pathologically high PLT counts (>500 000 PLT/µL) were detected in >50% of the cohort and extremely high platelet counts in >10%. However, associated thrombo-hemorrhagic complications were rare events affecting less than 10% (40/621= 6.4%) of the pats. Especially thrombosis was a rare (0.3%) complication whereas mild bleeding symptoms formed the majority of hemostaseological complications observed. Compared to recently published findings in adults (Sora F, et al. 2018; Br J Haematol 181:267-270, N= 1591 pats; Sandal R, et al. 2019; J Clin Oncol (Suppl) abstract #e18546, N= 2350 pats; Liu Z, et al. 2017; Onco Target Ther 10:3515-3520, N= 87 pats) the proportions of adult pats with extremely high platelet counts (Sora F: 5,5%, Sandal R: not listed; Liu Z: 25.3%) is in the same range (5% - 25%) as in pediatric patients (11.2%). Surprisingly, thrombo-hemorrhagic complications were observed more frequently in children (40/621= 6.4%) than in adults (Sora F: 9/1591= 0.5%, Liu Z: 1/85= 0.1%; Sandal R: 66/2350= 2.8%). As a word of caution this comparative analysis is weakened by its retrospective nature and a non-standardized reporting of bleeding signs. Mild bleeding signs in pats with high PLT counts can be caused by an acquired low plasma concentration of large VWF multimers as could be demonstrated in selected pediatric pats from this cohort. Systematic investigations on AVWS in children with CML have not been published so far and AVWS may be underdiagnosed in pediatric CML. Disclosures No relevant conflicts of interest to declare.

Background aims Natural killer (NK) cells, either naive or genetically engineered, are increasingly considered for cellular therapy of patients with malignancies. When using NK cells from peripheral blood, the number of expanded NK cells can be highly variable and the need for NK cell enrichment can make the process expensive. The NK-92 cell line (CD56+/CD3−) that was isolated from a patient with lymphoma has predictable high cytotoxic activity and can be expanded under good manufacturing practice conditions in recombinant interleukin-2. Methods Fifteen patients (age, 9–71 years) with advanced, treatment-resistant malignancies, either solid tumors/sarcomas (n = 13) or leukemia/lymphoma (n = 2), received two infusions of NK-92 cells, given 48 h apart. Three cohorts of patients were treated with escalating doses of NK-92 cells (n = 7 at 1 × 10 9 , n = 6 at 3 × 10 9 and n = 2 at 1 × 10 10 cells/m 2 ). Results No infusion-related or long-term side effects were observed. The dose of 10 10 cells/m 2 was considered the maximum expandable cell dose with the use of an established culture bag system. Three fourths of patients with lung cancer had some anti-tumor response. Only one patient of seven had development of human leukocyte antigen antibodies. The persistence of NK-92 cells (male origin) in the circulation was confirmed by Y chromosome–specific polymerase chain reaction in two female patients. Conclusions Infusions of NK-92 cells up to 10 10 cells/m 2 were well tolerated. Despite the allogeneic nature of NK-92, development of human leukocyte antigen antibodies in these patients with cancer appears to be rare. The cells can persist in the recipient's circulation for at least 48 h. Some encouraging responses were seen in patients with advanced lung cancer.