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We report the first large series (n=596) of pediatric acute myeloid leukemia (AML) focusing on modal numbers (MN) from the population-based NOPHO-AML trials. Abnormal karyotypes were present in 452 ...

Background Testicular dysfunction and infertility are of major concern in long-term survivors after allogeneic hematopoietic stem cell transplantation (HSCT). This study assesses predictive factors for very long-term testicular recovery after allogeneic HSCT in childhood and adolescence. Procedure Testicular volume, sperm production and long-term need of testosterone substitution were evaluated among 106 male survivors transplanted at Huddinge and Helsinki University Hospitals from 1978 through 2000, at a mean age of 8 ± 4.6 years (range 1–17). A mean ± SD of 13 ± 4.8 years (range 4–28) had elapsed since their HSCT and the mean age of the participants was 22 ± 6.0 years (range 12–42). An adult testicular volume was recorded in 74 patients at a mean age of 19 ± 3.3 years (range 14–36). Results Recipients conditioned with busulfan-based regimens or regimens containing only cyclophosphamide had significantly larger adult testicular volumes (mean volume 18 ml and 16 ml vs. 9 ml, P

Hyperleucocytosis in paediatric acute myeloid leukaemia (AML) is associated with increased morbidity and mortality. We studied hyperleucocytosis in 890 patients with AML aged 0-18 years registered in the Nordic Society of Paediatric Haematology and Oncology (NOPHO) registry, with special focus on very high white blood cell counts (WBC200 × 10/l). Eighty-six patients (10%) had WBC 100-199 × 10

Personalized medicine involves a comprehensive analysis of factors affecting a disease. Family history is an important but not a definitive indicator of inherited predisposition to malignancy and thus studying the germline gene aberrations alongside somatic variants is warranted. The significance of germline predisposition has been increasingly recognized in acute myeloid leukemia and is noted in the latest WHO classification.1,2,3Despite the recent progress in acute lymphoblastic leukemia (ALL) therapies, many adult patients with ALL still do poorly and there is a need for new biomarkers and therapy targets. The aim of our study was to identify and determine the frequency of germline mutations in known ALL genes, to discover new genes associated with ALL predisposition, and to compare the germline genetic background and respective consequences of pediatric and adult high-risk ALL. We examined exome sequencing data from biobanked samples of adult (50) and pediatric (68) patients with high-risk ALL (Finnish Hematological Registry and Biobank - FHRB, and clinical repositories). First, a candidate-gene analysis consisted of 92 genes previously associated with germline predisposition to ALL or syndromes predisposing to ALL. Variants with minor allele frequency of Second, an unbiased approach was applied to find novel genes predisposing to ALL by checking pathogenic variants in the same gene in at least two (adult/pediatric) patients and filtering by gene ontologies DNA repair, cell cycle, and lymphocyte differentiation; and by COSMIC cancer census genes. In both analyses, only statistically significantly more common variants in our series compared to normal population were included. We also conducted a mutational signature analysis on the samples. Our analysis (Table 1) demonstrates that 8% of adult and 10% pediatric study patients carried a pathogenic or likely pathogenic mutation in their germline in known ALL predisposing genes. All these mutations were at least 30-fold more frequent in our study series compared with allele frequencies in the normal population (p In conclusion, our results emphasize that germline predisposition is not rare among high-risk ALL patients. In addition to pediatric ALL patients, we show contributing germline variants also in adult patients. At least 20% of the adult ALL patients are transplanted and a potential germline basis of the disease should be considered when choosing the donor. Our analysis also reveals new information on the biology of high-risk ALL and may contribute to the future studies seeking for therapy options in this challenging patient category. Despite the anxiety that acknowledging inheritable factors may cause in patients, families, and caretakers, we encourage clinicians to integrate carefully interpreted germline data into patient care. References 1. Wartiovaara-Kautto U et al. Germline alterations in a consecutive series of acute myeloid leukemia. Leukemia. 2018. 2. Arber DA et al. The 2016 revision to the World Health Organization classification of myeloid neoplasms and acute leukemia. Blood. 2016. 3. Tawana K et al. Universal genetic testing for inherited susceptibility in children and adults with myelodysplastic syndrome and acute myeloid leukemia : are we there yet? Leukemia. 2018. Disclosures Porkka: Daiichi Sankyo: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Novartis: Consultancy, Research Funding. Heckman:Celgene: Research Funding; Novartis: Research Funding; Oncopeptides: Research Funding; Orion Pharma: Research Funding.

Relapse remains a major therapeutic challenge in children with acute myeloid leukemia (AML). Outcome after relapse may improve if preemptive therapy is initiated at first evidence of leukemia regrowth. Early detection of imminent relapse requires molecular measurable residual disease (MRD) monitoring after therapy completion. Today, this is possible only in about 40% of children with AML that harbor genetic abnormalities applicable for quantification using standardized qPCR assays. To enable disease surveillance for all patients, we developed patient-tailored deep sequencing (DS) MRD analysis, which provides highly sensitive detection of leukemia-specific mutations. We investigated the potential of this method for early relapse detection in peripheral blood (PB), the only easily accessible source for MRD sampling in children. PB samples were collected at monthly intervals during follow-up from 45 children diagnosed with AML and treated according to The Nordic Society of Pediatric Haematology and Oncology (NOPHO)-DBH AML 2012 protocol between January 2013 and May 2016 in Denmark, Norway, Sweden and Finland (508 samples, median 11 samples/patient, range 3-27). Nine patients with relapse (median age 5 years, range 0-8) had available diagnostic and relapse material and were included in this study. The patients displayed core binding factor abnormalities (n=3), KMT2A-rearrangements (n=3), monosomy 7 (n=1) or normal karyotype (n=2) at AML diagnosis. Leukemia-specific single nucleotide variants (SNVs) were identified with exome sequencing (ES) of sorted leukemic cells with lymphocytes or remission PB as constitutive DNA template. A variant allele frequency (VAF) with 95% confidence interval including 50% indicates presence of the mutation in all leukemic cells at diagnosis. With the exception of 2 cases with only subclonal mutations at diagnosis, leukemia-specific SNVs with VAF of 50% at diagnosis and persistence at relapse were selected as MRD targets. MRD target mutations were quantified in PB samples preceding overt relapse using patient-tailored DS assays with sensitivity of VAF 0.02%. In diagnostic samples, ES identified 53 leukemia-specific SNVs (median 4 SNVs/patient, range 2-12) of which 33 were also present at relapse (median 2 SNVs/patient, range 1-9). The number of mutations identified at diagnosis increased with age (Rs 0.83, p=0.006). All patients had at least one leukemia-specific SNV detected at both diagnosis and relapse. Twenty-one MRD target mutations (median 2 SNVs/patient, range 1-3) were quantified in PB (55 samples, median sampling interval 28 days, range 11-80) using DS. In 8/9 patients, at least one SNV was detected in PB before overt relapse occurred. The first PB sample showing MRD positivity (median VAF 0.14%, range 0.03-0.44) preceded hematological relapse at a median interval of 3 months (range 0-7.9). In 6 patients not preemptively treated, the median doubling time based on VAF increments was 7 days, with great variability between individuals and genotypes (range 4-28 days). Three patients had molecular relapse diagnosed by qPCR used in clinical diagnostics and received individualized preemptive treatment. In these 3 patients, DS detected mutations in PB for >100 days preceding overt relapse and the doubling times were 14, 25 and 36 days. In conclusion, DS of leukemia-specific mutations at frequent intervals in PB enables early detection of relapse and ES at diagnosis may identify SNVs applicable for such longitudinal MRD monitoring. This approach facilitates molecular disease surveillance and initiation of preemptive therapy in AML patients without established qPCR targets. Disclosures No relevant conflicts of interest to declare.

Background More than 60% of children with acute myeloid leukemia (AML) become long-term survivors. Most are cured using chemotherapy without hematopoietic stem cell transplantation (HSCT). We report on pubertal development and compare self-reported parenthood among AML survivors and their siblings. Procedure We included 137 children treated for AML according to the Nordic Society of Pediatric Hematology and Oncology (NOPHO)-AML-84, -88, and -93 trials, who were alive by June 2007. Patients with relapse or treated with HSCT were excluded. AML survivors participated in a physical and biochemical examination (n = 102) and completed a questionnaire (n = 101). One of their siblings completed an identical questionnaire (n = 84). Results At a median follow-up of 11 years (range 5–25) after diagnosis of AML the survivors (median age 16 years, range 5–36) were either prepubertal or had entered puberty normally. Serum levels of FSH, LH, testosterone, estradiol, sex hormone binding globulin (SHBG), inhibin A and B, and testicular volumes were within normal ranges. Anti-Mullerian hormone (AMH) levels were decreased in 5 of 40 postpubertal females. Mean reported age at menarche was 13.1 (range 11–17) years. Among survivors 15 years of age or older 31% of females reported pregnancies and 9% of males reported pregnancies in their partners, rates comparable with the frequency reported by their siblings. Conclusions Most AML survivors treated with chemotherapy had normal pubertal development and fertility, however, AMH levels were decreased in 13% of postpubertal females. Longer follow-up is necessary to evaluate possible risk of premature ovarian failure. Pediatr Blood Cancer 2013;60:1988–1995. © 2013 Wiley Periodicals, Inc.

Children with high-risk neuroblastoma (NBL) constitute a heterogenous group, but little attention has been paid to further subdivision of the high-risk group. Although the current therapies including multiple high-dose consolidations have neared their efficacy and tolerability limits, alternative therapies are needed. We wanted to define an ultrahigh-risk group among high-risk NBL patients, to be potential candidates for novel therapies given up-front. Children with high-risk NBL (n=59) treated at a single institution during 1987 to 2010 were evaluated for upfront prognostic factors at diagnosis and response to induction therapy. The overall outcome was not different during 1987 to 1994 versus 1995 to 2010. Therapy consisted of induction chemotherapy, surgery, and high dose-consolidation (single, tandem, or triple) with autologous stem cell rescue, followed by local irradiation and cis-retinoic acid. MYCN amplification and bone metastases were powerful upfront prognostic factors, and a combination of these determined an ultrahigh-risk group with a 5-year event-free survival of 0.125±0.083. The combination of MYCN amplification and bone metastases overruled the intensity of the therapy given and remained the only significant predictor (P

ObjectiveLong-term health sequelae of childhood-onset acute lymphoblastic leukemia (ALL) remain largely unknown. Low bone mineral content (BMC) and bone mineral density (BMD) are recognized complications, but it is unknown whether these persist until adulthood. We evaluated skeletal characteristics and their association with ALL therapy in long-term male ALL survivors.DesignThis cross-sectional cohort study included 49 long-term male ALL survivors and 55 age-matched healthy males.MethodsBMD and compression fractures were assessed by dual-energy X-ray absorptiometry; blood biochemistry was obtained for parameters of calcium homeostasis.ResultsThe ALL survivors (median age 29 years, range 25–38 years), assessed 10–38 years after ALL diagnosis, had lower lumbar spine (PPP=0.017) BMD than expected based on normative values. When compared with the controls (median age 30 years, range 24–36 years), the ALL survivors had lower lumbar spine BMC (P=0.014), lower whole-body BMC (PPConclusionsAt young adulthood, long-term male ALL survivors have significantly reduced BMC and BMD and a high prevalence of spinal compression fractures. Careful follow-up and active treatment of the recognized risk factors are warranted.

Context: Rapid progress in fertility preservation strategies has led to the investigation of ways in which fertile gametes could be generated from cryopreserved immature testicular tissue. Childhood cancer patients remain the major group that can benefit from these techniques. Other potential candidates include patients undergoing gonadectomy and patients with Klinefelter's syndrome and cryptorchid testes. This review aims to present an overview of the current state of knowledge in experimental germ cell transplantation, testicular tissue transplantation, and germ cell culture as fertility preservation methods for males. Methodology: We included English articles published in PubMed as well as personal files with the focus on studies including human or nonhuman material. Main Findings: Germ cell and testicular tissue transplantation demonstrate clinical options to mature germ cells from immature primate testicular tissue. The most promising approach involves autologous grafting of immature testicular tissu...

The aim of this study was to analyze the prevalence of frailty and physical health limitations among long-term survivors of high-risk neuroblastoma (HR NBL) and to investigate whether frail health is associated with variables of cardiovascular function, markers of inflammation and telomere length. A national study cohort of 19 (median age 22, range 16-30 years) long-term (>10 years) HR NBL survivors was studied and the findings were compared with 20 age- and sex-matched controls. Frailty was defined as ⩾3 of the following conditions: low muscle mass, low energy expenditure, slow running and weakness. The prevalence of frailty was significantly higher among the HR NBL survivors 9/19 (47%) than among the controls (0%). Thirteen (68%) of the survivors reported significant physical health limitations in vigorous activities, as opposed to none of the controls. The HR NBL survivors had significantly shorter telomere length and higher serum levels of high sensitivity C-reactive protein than did the controls. Frail health and poor physical functioning are prevalent among HR NBL survivors and suggest premature aging. Survivors with gonadal damage, very low fat mass percentage, low glycosylated hemoglobin A1c and increased common carotid artery intima-media thickness may be more prone to early aging after high dose therapy.

Early response after induction is a prognostic factor for disease outcome in childhood acute myeloid leukaemia (AML). Residual disease (RD) detection by multiparameter flow cytometry (MFC) was performed at day 15 and before consolidation therapy in 101 patients enrolled in the Nordic Society of Paediatric Haemato-Oncology AML 2004 study. A multicentre laboratory approach to RD analysis was used. Event-free survival (EFS) and overall survival (OS) was significantly different in patients with and without RD at both time points, using a 0·1% RD cut-off level. RD-negative and -positive patients after first induction showed a 5-year EFS of 65 ± 7% and 22 ± 7%, respectively (P < 0·001) and an OS of 77 ± 6% (P = 0·025) and 51 ± 8%. RD-negative and -positive patients at start of consolidation therapy had a 5-year EFS of 57 ± 7% and 11 ± 7%, respectively (P < 0·001) and an OS of 78 ± 6% and 28 ± 11%) (P < 0·001). In multivariate analysis only RD was significantly correlated with survival. RD before consolidation therapy was the strongest independent prognostic factor for EFS [hazard ratio (HR):5·0; 95% confidence interval (CI):1·9-13·3] and OS (HR:7·0; 95%CI:2·0-24·5). In conclusion, RD before consolidation therapy identifies patients at high risk of relapse in need of intensified treatment. In addition, RD detection can be performed in a multicentre setting and can be implemented in future trials.

Left ventricular mass and ambulatory blood pressure are increased in long-term survivors of childhood cancer after autologous SCT

Boys faced with future sterility as a result of the need of a sterilizing cancer therapy might avoid this fate by engraftment of cryopreserved immature testicular tissue after therapy is completed. Efforts to address this important survivorship issue have been encouraged by reports of the long-term survival and proliferation of human spermatogonia after xenotransplant of cryopreserved immature testicular tissue into immunocompromised murine hosts. However, spermatogenic arrest at the pachytene spermatocyte stage that occurs in this situation has been associated with a failure in sperm production. In this study, we used a prepubescent simian model to address the possibility that testicular tissue engraftment is insufficiently supported in the model to allow suitable maturation of germ cells. Briefly, we carried out autologous orthotopic grafting of cryopreserved testicular tissue from four prepubescent monkeys and one pubescent rhesus monkey after testicular irradiation and castration of the host animal. Five months after implantation of scrotal grafts, we determined that 3% to 7% of the autografts could be recovered with spermatogenesis proceeding through spermatozoa formation in 13% to 17% of the seminiferous tubules formed in the grafts. In contrast, Sertoli cell-only tubules were detected in parallel xenografts transplanted into immunocompromised mice. Our results show that cryopreservation of testicular tissue from prepubescent primates can maintain the fully functional capacity of spermatogonia to produce sperm, but that host conditions are critical for spermatogenic maturation. Furthermore, our results establish an initial perspective on the quantity of cryopreserved material needed to ensure success in preserving fertility through testicular tissue grafts. Cancer Res; 72(20); 5174–8. ©2012 AACR.

There are no data on the role of postconsolidation therapy with gemtuzumab ozogamicin (GO; Mylotarg) in children with acute myeloid leukemia (AML). The NOPHO-AML 2004 protocol studied postconsolidation randomization to GO or no further therapy. GO was administered at 5 mg/m2 and repeated after 3 weeks. We randomized 120 patients; 59 to receive GO. Survival was analyzed on an intention-to-treat basis. The median follow-up for patients who were alive was 4.2 years. Children who received GO showed modest elevation of transaminase and bilirubin without signs of veno-occlusive disease. Severe neutropenia followed 95% and febrile neutropenia 40% of the GO courses. Only a moderate decline in platelet count and a minor decrease in hemoglobin occurred. Relapse occurred in 24 and 25 of those randomized to GO or no further therapy. The median time to relapse was 16 months versus 10 months (nonsignificant). The 5-year event-free survival and overall survival was 55% versus 51% and 74% versus 80% in those randomized to receive GO or no further therapy, respectively. Results were similar in all subgroups. In conclusion, GO therapy postconsolidation as given in this trial was well tolerated, showed a nonsignificant delay in time to relapse, but did not change the rate of relapse or survival (clinicaltrials.gov identifier NCT00476541).

Background Outcome of high risk neuroblastoma (NBL) remains unsatisfactory in spite of intensive treatment efforts. Consolidation with high-dose (HD) chemotherapy and autologous stem cell transplantation (ASCT) has been intensified with tandem and triple cycles with promising results. Our purpose was to improve the outcome with two or three HD-consolidations. Methods Thirty six children with high risk NBL, diagnosed 1995–2010, had intensive induction and surgery, and were stratified to single, tandem or triple HD-therapy and ASCT, followed by local irradiation and cis-retinoic acid. In inoperable patients surgery was facilitated by preoperative HD-melphalan. Long-term outcome of our old cohort from 1987–1994 was updated. Results Ten year event-free survival (EFS) from diagnosis was 0.44+/−0.10 of the old and 0.43+/−0.085 of the new cohort. EFS from the last ASCT was 0.53 +/−0.12 and 0.48+/−0.091, respectively. Preoperative HD-melphalan rendered 73% of bulky primaries operable in the new cohort. The 5-yr EFS from ASCT was 0.46+/−0.15 for single and 0.73+/−0.15 for tandem ASCT (P = 0.19). All triple ASCT patients, selected by poor/slow response, relapsed or died. Conclusions Thiotepa- and melphalan based HD regimens, with or without total body irradiation (TBI), appeared to give an outcome comparable to major NBL study groups with acceptable toxicity. Tandem HD therapy gave a 5-year EFS of 73%, whereas a third HD consolidation did not offer any additional advantage for ultra high risk patients with slow response. Pediatr Blood Cancer 2012; 59: 1190–1197. © 2012 Wiley Periodicals, Inc.

Trisomy 8 (+8) is a common cytogenetic aberration in acute myeloid leukemia (AML); however, the impact of +8 in pediatric AML is largely unknown. We retrospectively investigated 609 patients from the NOPHO-AML database to determine the clinical and cytogenetic characteristics of +8 in pediatric AML and to investigate its prognostic impact. Complete cytogenetic data were available in 596 patients (98%) aged 0-18 years, diagnosed from 1993 to 2012, and treated according to the NOPHO-AML 1993 and 2004 protocols in the Nordic countries and Hong Kong. We identified 86 patients (14%) with +8. Trisomy 8 was combined with other cytogenetic aberrations in 68 patients (11%) (+8 other) and in 18 patients (3%), it was the sole abnormality (+8 alone). Trisomy 8 was associated with FAB M5 (36%) but otherwise clinically comparable with non-trisomy 8 patients. Trisomy 8 was favorable in patients of young age and with t(9;11). Trisomy 8 alone was associated with older age (median age 10.1 years), FAB M2 (33%), and FLT3-ITD mutations (58%). The 5-year event-free survival for patients with +8 alone was 50% and 5-year overall survival was 75%. In conclusion, +8 is one of the most common cytogenetic aberrations in pediatric AML. Trisomy 8 positive AML is a heterogeneous group and the majority of cases have additional cytogenetic aberrations. Patients with +8 alone differed from patients with +8 other and were associated with older age, FAB M2, and FLT3-ITD aberrations. There were no differences in survival despite the more frequent occurrence of FLT3-ITD in +8 alone. © 2016 Wiley Periodicals, Inc.

Hedgehog (Hh) signalling has a crucial role in testis development. Sertoli cell-derived desert hedgehog (DHH) guides the formation of testis cords and differentiation of foetal-type Leydig cells.Dhhmutant mice are infertile due to a block in germ cell differentiation, hypogonadism and hypoandrogenism. Hh signalling pathway components are also expressed in postnatal testis. In the rat testis the transcription factor of the Hh pathway, glioma-associated oncogene homologue (GLI1), is expressed by a wide variety of germ cells. This suggests that Hh signalling is involved in spermatogenesis at many different levels. Our data show that canonical Hh signalling is turned off in early condensing spermatids that strongly express the negative regulator of the pathway, suppressor of fused (SUFU). Most of the Hh pathway specific mRNAs display the highest values in stages II–VI of the rat seminiferous epithelial cycle. The key endocrine regulator of germ cell differentiation, FSH, down-regulatesDhhmRNA levelsin vitro. Hh signalling inhibitionin vitroleads to massive apoptosis of germ cells. In prepubertal rat testis imatinib mesylate-induced inhibition of tyrosine kinases impinges onDhhtranscript levels and Hh signalling. Our data indicate that Hh signalling is part of the paracrine signalling network in the rat testis. It promotes the survival of germ cells and is suppressed by FSH.

Objective To assess testicular function and its determinants in adult survivors of childhood acute lymphoblastic leukemia (ALL) at a median time of 20 years after ALL therapy. Design Prospective investigation. Setting University hospital. Patient(s) Fifty-one male long-term survivors and 56 age-matched controls (median age of survivors at ALL diagnosis was 5 years, range: 1 to 15 years, and at the study 29 years, range: 26 to 38 years). Intervention(s) None. Main Outcome Measure(s) Testicular size (mean value of both testicular volumes), serum hormone concentrations, semen quality, and number of children fathered correlated with ALL therapy. Result(s) Survivors treated with 0–10 g/m 2 of cyclophosphamide had sperm quality and fertility rates comparable with those of controls, but the serum free-testosterone in the survivors treated with cyclophosphamide was lower than in controls (median: 213 pmol/L, range: 189–260 vs. 296 pmol/L, range: 242–338, respectively). Cranial irradiation without cyclophosphamide did not affect semen quality, fertility, or testosterone levels. None of the survivors of a high cumulative dose of cyclophosphamide (>20 g/m 2 ) and testicular irradiation (10–24 Gy) had fathered a child. Testicular size was shown to be better than serum inhibin B in predicting nonazoospermic semen samples or fertility. Conclusion(s) Treatment of childhood ALL with 0–10 g/m 2 of cyclophosphamide and cranial irradiation does not affect fertility or semen quality but may impair long-term Leydig cell function.

Background Although infertility is a serious concern in survivors of pediatric cancers, little is known about the influence of the degree of sexual maturation at the time of irradiation on spermatogenic recovery after treatment. Thus, we address this question in a non-human primate model, the rhesus monkey (Macaca mulatta). Methods Two pubertal (testis size 3 and 6.5 ml, no sperm in ejaculate) and four prepubertal (testis size 1 ml, no sperm in ejaculate) macaques were submitted to a single fraction of testicular irradiation (10 Gy). Unilateral autologous transfer of cryopreserved testis cells was performed 2 months after irradiation. Testicular volume, histology and semen parameters were analyzed to assess irradiation effects and testicular recovery. Results Irradiation provoked acute testis involution only in the two pubertal monkeys. Subsequently, testis sizes recovered and sperm was present in the ejaculates. Longitudinal outgrowth of seminiferous tubules continued, and, in testes without autologous cell transfer, 4-22% of tubular cross sections showed spermatogenesis 2 years after irradiation. In contrast, the four prepubertal monkeys showed neither a detectable involution as direct response to irradiation, nor a detectable growth of seminiferous tubules later. However, two of these animals showed spermarche 2 years after irradiation, and 8-12% of tubules presented spermatogenesis. One prepubertally irradiated monkey presented fast growth of one testis after cell transfer, and showed spermarche 1 year after irradiation. The infused testis had spermatogenesis in 70% of the tubules. The contralateral testis remained smaller. Conclusion We conclude that irradiation before puberty has a severe detrimental effect on outgrowth of seminiferous tubules. But, within the seminiferous epithelium, spermatogenetic recovery occurs at a low rate with no detectable relation to the maturity of the epithelium at irradiation. We also show that autologous testis cell transplantation can enhance spermatogenesis, but only in isolated cases.

The testis has been shown to be highly susceptible to the toxic effects of cancer therapy at all stages of life. Young cancer survivors are approximately half as likely as their siblings to sire a pregnancy. Radiation therapy to the testes and high cumulative dose of alkylating agents are the major factors decreasing the probability of fertility. This review aims to present an overview of the current state of knowledge in mechanisms how human spermatogonia proliferate and differentiate and how cancer therapy affects germ cells, what are the options for fertility preservation and what are the clinical risks and limitations related to such procedures. This area of research is discussed in the context of the potential future options that may become available for preserving fertility in male cancer patients.

Acute myeloid leukemia (AML) represents 20% of the acuteleukemiacasesinchildrenandadolescents.IntheNordiccountries,AML is diagnosed in approximately 30 children annually in a totalchildpopulationof4.5millionbelowtheageof15years.Thepasttwodecadeshaveseenamarkedimprovementinsurvival.TheresultsoftheNOPHO-AMLstudies(NordicSocietyofPediatricHematologyandOncology)areamongthebestintheworldwitha5-yearsurvivalrate of 65% [1,2]. The late morbidity and mortality after the veryintensive treatment therefore deserve attention.Long-termsurvivorsofchildhoodcancerareatriskofdevelopingseveraladverseoutcomesincludingearlydeath,secondneoplasms,organ dysfunction (e.g., cardiac and pulmonary), growth disturb-ance, reduced fertility, impaired intellectual function, difficultiesinobtainingemploymentandinsurance,andreducedqualityoflife[3–5]. Previous studies have reported common late effects afterchildhood AML [6–15]. In the Childhood Cancer Survivor Study(CCSS),62%ofAMLsurvivorsreportedachronicmedicalcondition[6]. However, most previous studies included rather few AMLsurvivors whose therapy varied considerably. Cranial irradiationhad been givento 9–100% of patients, and hematopoietic stem celltransplantation (HSCT) had been used in 0–60%. Many of the lateeffects reported in previous studies were probably caused by thesetreatments [7,9,10]. From 1984 to 2003, approximately 50% ofNordic children with AML were cured with chemotherapy only.Cranialirradiationwasnotused,andcumulativedosesofanthracy-clines were lower than in most other protocols [1,2]. However, thechemotherapyusedtocureAMLremainedveryintensiveanditsusewasassociatedwithmajoracutetoxicity,includingahighfrequencyof both early (6%) and late toxic death (7%) [2]. Limited data existabout the long-term mortality, morbidity, and social outcomes ofAML patients treated with chemotherapy only.The objective of the Nordic AML Late Effect Study was toinvestigatethespectrum,frequencyandpossibleriskfactorsforlateeffects of childhood AML cured by chemotherapy only. This studycomparedtheself-reporteduseofhealthcareservices,healthexperi-ence,socialoutcomes,andlifestylebehaviorofAMLsurvivorswiththose of their sibling controls.

Hereditary predisposition has been ever since implicated in the etiology of childhood myelodysplastic syndromes (MDS). Until recently, GATA2 deficiency prevailed as a major germline cause in pediatric primary MDS. In the past 2 years, we and others identified germline mutations in paralogue genes SAMD9 and SAMD9L residing on chromosome 7q21.2 as new systemic diseases with high propensity for MDS with monosomy 7. Although initially, mutations in SAMD9 and SAMD9L genes were associated with MIRAGE and Ataxia-Pancytopenia syndromes, respectively, with recent reports the phenotypes are becoming more intertwined. Nevertheless, the predisposition to MDS with monosomy 7 (-7) remains a common clinical denominator. Both genes are categorized as negative regulators of cellular proliferation and mutations were shown to be activating. Because of their high evolutionary divergence, classical in silico prediction is erratic, thereby establishing in vitro testing as the current gold standard for pathogenicity evaluation. The objectives of this study were to define the prevalence of SAMD9/9L germline mutations in primary pediatric MDS, and to describe the clinical phenotype and outcome. In addition, we aimed to characterize the somatic mutational architecture and develop a functional scoring system. Within the cohort of 548 children and adolescents with primary MDS diagnosed between 1998 and 2016 in Germany, 43 patients (8%) carried SAMD9/9L mutations that were mutually exclusive with GATA2 deficiency and known constitutional bone marrow (BM) failure. MDS type refractory cytopenia of childhood was diagnosed in 91% (39/43), and MDS with excess blasts in 9% (4/43) of mutated cases. Karyotype at diagnosis was normal in 58%, and -7 was detected in 37% of SAMD9/9L cohort. Within MDS subgroup with -7 (n=74), SAMD9/9L mutations accounted for 22% of patients. Notably, the demographics, familial disease, diagnostic blood and BM findings, overall survival (OS) and the outcome after HSCT were not influenced by mutational status in our study cohort (n=548). At the last follow up, 88% (38/43) of SAMD9/9L MDS patients were alive; 35/43 had been transplanted with a 5-year-OS of 85%. Next, we added 26 additional cases with SAMD9/9L mutations diagnosed in Europe within EWOG-MDS studies. In the total cohort of 69 germline mutated patients we found a total of 75 SAMD9/9L mutations, of which 67 were novel. Of those we tested 47 using a HEK293 cell in vitro system and 45/47 mutants inhibited proliferation. While 53/69 patients carried only single germline mutations (missense in 50/53 and truncating in 3/53), in the remaining 16 patients, 11 additional truncating and 7 missense mutations were found. We did not observe an association between germline mutation and phenotype. Immunological issues (e.g. recurring infections, low Ig) were described in 32%/50% of SAMD9/9L-mutated patients, while physical anomalies were very heterogeneous and reported in ~50% of patients in both mutational groups. Intriguingly, genital phenotypes occurred in 40% of SAMD9L, while neurological problems were present in 30% of SAMD9 - mutational subgroups. To elucidate the somatic mutational landscape, we performed whole exome and deep sequencing of 58 SAMD9/9L patients and identified recurrent somatic mutations in known oncogenes that were earlier associated with pediatric MDS: SETBP1 (10%), RUNX1 (7%), ASXL1 (5%), EZH2 (5%), CBL (3%). The identified somatic mutations occurred in association with monosomy 7 background (18/20). Finally, we utilized the results from functional testing of the 47 SAMD9/9L variants as our test cohort to develop combinatorial in silico scoring. The rationale was to decrease the dependency on functional validation. Based on the results of 20 in silico tools we could concatenate a matrix of 5 algorithms to resolve the pathogenicity of >80% of variants. Using this model, all variants predicted as pathogenic showed also growth-restrictive effect in vitro. In summary, pathogenic SAMD9/9L germline mutations account for 8% of primary pediatric MDS and 22% of MDS/-7. The mutations identified are heterogeneous and their effect can be predicted using a combinatorial in silico - in vitro approach. Finally, the clinical outcome and somatic mutational landscape are not influenced by the mutational status. Disclosures Locatelli: Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Bellicum: Consultancy, Membership on an entity's Board of Directors or advisory committees; bluebird bio: Consultancy; Miltenyi: Honoraria; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees. Niemeyer:Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees.

Isolation of spermatogonial stem cells before potentially sterilizing cancer therapy, followed by transplantation of these cells into the testis after such treatment, may be an effective approach to prevent infertility among prepubertal boys suffering from acute lymphoblastic leukemia (ALL). A key clinical consideration in this context is the timing of biopsy, if collection of spermatogonia could be delayed from diagnosis to the later phase of leukemia treatment, better patient selection could be offered.The objective of the study was to examine the routine testicular biopsy material collected to detect testicular leukemia to evaluate if treatment for leukemia affects numbers and maturation of the spermatogonia during the prepubertal period.The study involved 28 testicular biopsies from 23 prepubertal boys treated for ALL.Samples were stained immunohistochemically to evaluate the expression of the spermatogonial markers MAGE 4A, OCT4, CD9, and AP2gamma, and of the Sertoli cell marker WT-1. To relate these findings to gonadal function after sexual maturation, the surviving patients were evaluated as adults.Several MAGE 4A-, CD9-, or OCT4-positive spermatogonia were detected in testicular biopsies after standard risk therapy without cyclophosphamide, whereas their numbers were significantly reduced in six patients receiving high-risk ALL therapy involving cyclophosphamide. No significant alteration in spermatogonial numbers was associated with testicular leukemia. All patients not treated with cyclophosphamide recovered normal testicular function, with normal sperm quality and endocrine function.Treatment for childhood leukemia without high-dose cyclophosphamide seldom depletes the spermatogonial stem cell pool totally.

Spermatogonial stem cells open novel strategies for preservation of testicular tissue and fertility preservation in boys and men exposed to gonadotoxic therapies. This review provides an update on the physiology of spermatogonial stem cells in rodent and primate testes. Species-specific differences must be considered when new technologies on testicular stem cells are considered. Germ cell transplantation is presented as one novel and promising strategy. Whereas this technique has become an important research tool in rodents, a clinical application must still be regarded as experimental and many aspects of the procedure need to be optimized prior to a safe and efficient clinical application in men. Testicular grafting opens another exciting strategy for fertility preservation. Autologous and xenologous transfer of immature tissue revealed a high regenerative potential of immature testicular tissue. Grafting was applied in rodents and primates and resulted in the generation of sperm. Further research is needed before an application in humans can be considered safe and efficient. Despite the current limitations in regard to the generation of sperm from cryopreserved male germline cells and tissues, protocols for cryopreservation of testicular tissue are available and reveal a promising outcome. Since future improvements of germ cell transplantation and grafting approaches can be assumed, bioptic retrieval and cryopreservation of testicular tissue fragments should be performed in oncological patients at high risk of fertility loss since this is their only option to maintain their fertility potential.

Elimination of contaminating malignant cells is crucial to avoiding cancer relapse in association with transplantation of autologous spermatogonial stem cells. In the clinical setting, there is presently no effective procedure for separating testicular cells from cancer cells. Here, CD4, a selective surface marker for Roser's rat leukaemic T-cells, was utilized to eliminate cancer cells from testicular cell samples from leukaemic piebald variegated (PVG) rats by magnetic-activated cell sorting (MACS). All animals receiving MACS-selected testicular cells died within 14-15 days. Only one-third of the contaminating leukaemic cells could be removed from testicular samples. An increase in antibody concentration enhanced the proportion of leukaemic cells removed from 27 to 49%. Variations in the cell size and expression of surface antigens on testicular leukaemic cells were the major obstacles to purification based on this marker. It is concluded that MACS does not prevent transmission of leukaemia to syngenic PVG rats when cells from leukaemic testes are used for testicular cell transplantation.

Imatinib mesylate (Glivec, STI 571; Novartis), a small-molecular analog of ATP that potently inhibits the tyrosine kinase activities of Bcr-Abl, PDGFR-alpha, PDGFR-beta, c-Fms, Arg and c-kit, is one of the novel molecularly targeted agents being introduced into cancer therapy. Stem cell factor (SCF)/c-kit and platelet-derived growth factor (PDGF) signaling pathways regulate postnatal formation of the pools of spermatogonial stem cells and Leydig cells in the rat testis. The effect of short postnatal imatinib exposure on fertility of the male rats and offspring of these animals were investigated. Imatinib significantly reduced the litter size sired by the treated animals and led to permanently slightly elevated serum levels of the gonadotropins. Testicular morphology and mRNA levels of ligands and receptors involved in stem cell factor/c-kit and PDGF signaling returned to control levels, and the offsprings were born healthy. Our findings indicate that treatment of cancer with certain molecularly targeted drugs may have latent effects on testicular development by inhibiting specific physiological signaling pathways.

The tyrosine kinase receptor c-kit and its interaction with the ligand, stem cell factor (SCF), play an essential role in the developing testis. C-kit is important for the development of the Leydig cells and for the migration, proliferation and survival of spermatogonia. Platelet-derived growth factor (PDGF) and its tyrosine kinase receptor (PDGFR) are important for the development of Leydig cells and myoid cells. The chemotherapeutic agent, imatinib mesylate (STI571, Glivec; Novartis) inhibits both of these tyrosine kinase receptors. Three-day treatment of immature male rats (SD) with imatinib (150 mg/kg) on postnatal days 5-7 delayed the formation of germ-line stem cell pool, reduced proliferation of type A spermatogonia and induced germ cell apoptosis. PDGFR-mediated proliferation of mesenchymal myoid precursors was also decreased and the length of the seminiferous cord was reduced. However, at the age of 11 weeks the exposed animals had normal epididymal sperm counts, whereas plasma levels of luteinizing hormone and follicle stimulating hormone were significantly increased. Imatinib serves as a good tool to study postnatal formation of the male germ-line stem cell pool and factors determining the final testicular size. As development of the human testis is controlled by the same mechanisms, further studies with primate and human models are needed to explore whether imatinib affects the testis in children as well.

BACKGROUND: Banking of testicular tissue from pre-pubertal boys before gonadotoxic treatment is a crucial step in fertility preservation. We wanted to find optimal methods for cryopreservation of testicular tissue from pre-pubertal boys, modifying techniques developed for fetal and adult human testicular tissue cryopreservation. METHODS: Testicular tissue was collected from five pre-pubertal boys undergoing gonadotoxic treatment in a clinical programme. Two freezing protocols, originally developed for fetal and adult human testicular tissue, were applied for pre-pubertal testicular tissue cryopreservation. In both methods, 5% dimethyl sulphoxide (DMSO) was used as a cryoprotectant. The integrity of the tissue was investigated in non-frozen tissue cultured for 24 h and in cryopreserved-thawed tissue, using two different programmes. We also analysed frozen–thawed samples cultured for 24 h in comparison with untreated fresh fixed control tissue. Immunohistochemical analysis using anti-MAGE-A4, vimentin and CD34 monoclonal antibodies was performed in order to visualize and characterize the cryodamage of the different testicular cells and compartments. The structure of the tissue was evaluated using light microscopy. Qualitative control analysis was performed using transmission electron microscopy. RESULTS: No clear structural changes were observed in the fresh, fresh cultured and cryopreserved testicular tissue after using the protocol developed for adult testicular tissue. The programme earlier successfully used for human fetal testicular tissue cryopreservation caused more tissue damage. CONCLUSIONS: Pre-pubertal testicular tissue from boys facing gonadotoxic treatment survives cryopreservation, can be cryobanked and hopefully used for fertility preservation. Slow programmed freezing with DMSO as a cryoprotectant is efficient in maintaining the spermatogonia, Sertoli cells and stromal compartment during freezing, thawing and tissue culture.

In the present population-based study, we compared the clinical data of testicular relapses with and without concurrent bone marrow relapse and clinical data of the relapses in other locations among boys with acute lymphoblastic leukaemia (ALL), in order to study the possible evidence of early sequestration and local regulation of leukaemic lymphoblast in the testis of humans. The results suggest that the pathogenesis of isolated testicular relapse (T) and testicular relapse with a concurrent bone marrow relapse (T + BM) is likely to be similar. Isolated and non-isolated testicular relapses appeared late after the achievement of remission (T 34 +/- 16 months, T + BM 32 +/- 15 months) in ALL compared to relapses in other locations (CNS 23 +/- 11 months, BM 25 +/- 19 months). The better prognosis after testicular relapses (estimated second event free survival probability, 2-EFS: T 0.63, T + BM 0.32) compared to bone marrow relapse (2-EFS: BM 0.13) further suggests that testicular relapse with a concurrent bone marrow relapse possibly originates from the isolated testicular relapse, and that the isolated testicular relapse is a separate entity and not a manifestation of systemic recurrence. Higher frequencies of isolated and non-isolated testicular relapses (T 9%, T + BM 5%) were observed among boys with onset of ALL in early puberty (10-12 y) compared to those among younger (T 4%, T + BM 2%) and older (T 0%, T + BM 0%) boys. The late occurrence, the possible association with hormonal maturation and the good prognosis after testicular relapses suggest a possible local regulation of the residual leukaemic lymphoblast in human testis.

Accurate analysis and quantification of different testicular cell populations are of central importance in studies of male reproductive biology. The traditional histomorphometric and immunohistochemical methods remain the gold standard in studying the complex dynamics of the testicular tissue. Through past years advances have been made in the application of flow cytometry for the rapid analysis of testicular cell populations. Detection of DNA content and of surface antigens and fluorescent reporters have been widely used to analyze and sort cells. Detection of intracellular antigens can broaden the possibilities of applying flow cytometry in studies of male reproduction. Here, we report a detailed protocol for the preparation of rat testicular tissue for detection of intracellular antigens by flow cytometry, and a pipeline for subsequent data analysis and troubleshooting. Rat testicular ontogenesis was chosen as the experimental model to validate the performance of the assay using vimentin and gamma H2AX as intracellular markers for the somatic and spermatogenic cells, respectively. The results show that the assay is reproducible and recapitulates the rat testis ontogenesis.

High-dose therapy (HDTx) with autologous stem cell rescue has been widely applied in very-poor-risk pediatric solid tumors. Promising data have become available with the use of high-dose busulfan, whereas high-dose (HD) thiotepa is less commonly used. We report retrospectively our single-institution experience from 1986 to 2012 of single and tandem HDTx with special emphasis on HD-thiotepa as the backbone of HD regimen in Ewing family tumors, including all 24 patients in the Helsinki University Hospital referral area in population-based fashion (Ewing sarcoma 9, Askin tumor 9, peripheral neuroectodermal tumor 6). The 10-year overall survival for the entire cohort was 0.73±0.01. Thirteen out of the 24 underwent HDTx (10 single, 3 tandem). The HDTx regimen consisted of HD-thiotepa (900 mg/m), VP16, and carboplatin. Additional HD-melphalan and total body irradiation were used in the tandem regimens. There was no toxic mortality. The 5-year event-free survival was 0.73±0.16 for high-risk cases transplanted in 1CR. In the relapse group, 1 out of the 3 survived. Radiotherapy to axial sites was given safely in combination with HD-thiotepa in all 3 patients. Thiotepa-based HDTx approach resulted in an encouraging outcome without toxic mortality for high-risk patients. HD-thiotepa merits further studies in larger controlled series.

Auto-transplant of cryopreserved ovarian tissue in leukemia patients carries a risk to reintroduce malignant cells. Maturation of ovarian follicles in vitro is a promising strategy to overcome the leukemic cell contamination. The follicle development and survival in 14 cryopreserved ovarian tissues with leukemia-specific PCR marker was evaluated after 7 or 14 days culture. Minimal residual disease (MRD) quantification was assessed by real-time quantitative PCR in order to identify the MRD positive (n = 6) and negative (n = 8) samples and to monitor levels of MRD before and after culture. The morphology of ovarian follicles were studied by light microscopy. After culture, no statistical significant differences were detected in follicle densities between MRD positive- and negative samples. Ovarian MRD either decreased below undetectable or fluctuated near the baseline level after 7 and 14 days in culture. This study provides quantitative in vitro evidence that leukemia contamination does not affect the follicle survival in cryopreserved ovarian tissue.

Studies on adolescents and young adults with acute lymphoblastic leukemia suggest better results when using pediatric protocols for adult patients, while corresponding data for acute myeloid leukemia (AML) are limited.We investigated disease characteristics and outcome for de novo AML patients 10-30 years old treated in pediatric or adult departments. We included 166 patients 10-18 years of age with AML treated according to the pediatric NOPHO-protocols (1993-2009) compared with 253 patients aged 15-30 years treated in hematology departments (1996-2009) in the Nordic countries.The incidence of AML was 4.9/million/year for the age group 10-14 years, 6.5 for 15-18 years, and 6.9 for 19-30 years. Acute promyelocytic leukemia (APL) was more frequent in adults and in females of all ages. Pediatric patients with APL had similar overall survival as pediatric patients without APL. Overall survival at 5 years was 60% (52-68%) for pediatric patients compared to 65% (58-70%) for adult patients. Cytogenetics and presenting white blood cell count were the only independent prognostic factors for overall survival. Age was not an independent prognostic factor.No difference was found in outcome for AML patients age 10-30 years treated according to pediatric as compared to adult protocols.

The aim of the study was to evaluate arterial morphology and function in a national cohort of long-term survivors of high-risk neuroblastoma (NBL) treated with high-dose chemotherapy and autologous hematopoietic stem cell transplantation with or without total body irradiation (TBI).Common carotid, femoral, brachial, and radial artery morphology were assessed with very-high-resolution vascular ultrasound (25-55 MHz), and carotid artery stiffness and brachial artery flow-mediated dilatation measured with conventional vascular ultrasound in 19 adult or pubertal (age 22.7 ± 4.9 years, range 16-30) NBL survivors transplanted during 1984-1999 at the mean age of 2.5 ± 1.0 years. Results were compared with 20 age- and sex-matched healthy controls. The cardiovascular risk assessment included history, body mass index, fasting plasma lipids, glucose, and 24-h ambulatory blood pressure (BP). The survivors had consistently smaller arterial lumens, increased carotid intima-media thickness (IMT), plaque formation (N = 3), and stiffness, as well as increased radial artery intima thickness (N = 5) compared with the control group. Survivors displayed higher plasma triglyceride and cholesterol levels, and increased heart rate, as well as increased systolic and diastolic BPs. TBI (N = 10) and a low body surface area were independent predictors for decreased arterial lumen size and increased IMT. Three out of five survivors with subclinical intima thickening had arterial plaques. Plaques occurred only among TBI-treated survivors.Long-term childhood cancer survivors treated with TBI during early childhood display significant signs of premature arterial aging during young adulthood.

A quarter of cancers diagnosed in those under 18 years of age are leukemias, another quarter being tumors of the central nervous system. The remaining cancers are solid tumors occurring elswehere in the body, most commonly lymphomas, soft tissue and bone sarcomas, neuroblastomas and Wilms tumors. In almost all cases, the treatment of these solid tumors consists of combinations of surgery, cytotoxic drugs and radiotherapy. Although the prognoses have improved, they exhibit variation even within tumor groups. New targeted therapies are being developed, but for the time being they do not have any significant role.

STUDY QUESTION:What clinical practices, patient management strategies and experimental methods are currently being used to preserve and restore the fertility of prepubertal boys and adolescent males?SUMMARY ANSWER:Based on a review of the clinical literature and research evidence for sperm freezing and testicular tissue cryopreservation, and after consideration of the relevant ethical and legal challenges, an algorithm for the cryopreservation of sperm and testicular tissue is proposed for prepubertal boys and adolescent males at high risk of fertility loss.WHAT IS KNOWN ALREADY:A known late effect of the chemotherapy agents and radiation exposure regimes used to treat childhood cancers and other non-malignant conditions in males is the damage and/or loss of the proliferating spermatogonial stem cells in the testis. Cryopreservation of spermatozoa is the first line treatment for fertility preservation in adolescent males. Where sperm retrieval is impossible, such as in prepubertal boys, or it is unfeasible in adolescents prior to the onset of ablative therapies, alternative experimental treatments such as testicular tissue cryopreservation and the harvesting and banking of isolated spermatogonial stem cells can now be proposed as viable means of preserving fertility.STUDY DESIGN, SIZE, DURATION:Advances in clinical treatments, patient management strategies and the research methods used to preserve sperm and testicular tissue for prepubertal boys and adolescents were reviewed. A snapshot of the up-take of testis cryopreservation as a means to preserve the fertility of young males prior to December 2012 was provided using a questionnaire.PARTICIPANTS/MATERIALS, SETTING, METHODS:A comprehensive literature review was conducted. In addition, survey results of testis freezing practices in young patients were collated from 24 European centres and Israeli University Hospitals.MAIN RESULTS AND THE ROLE OF CHANCE:There is increasing evidence of the use of testicular tissue cryopreservation as a means to preserve the fertility of pre- and peri-pubertal boys of up to 16 year-old. The survey results indicate that of the 14 respondents, half of the centres were actively offering testis tissue cryobanking as a means of safeguarding the future fertility of boys and adolescents as more than 260 young patients (age range less than 1 year old to 16 years of age), had already undergone testicular tissue retrieval and storage for fertility preservation. The remaining centres were considering the implementation of a tissue-based fertility preservation programme for boys undergoing oncological treatments.LIMITATIONS, REASONS FOR CAUTION:The data collected were limited by the scope of the questionnaire, the geographical range of the survey area, and the small number of respondents.WIDER IMPLICATIONS OF THE FINDINGS:The clinical and research questions identified and the ethical and legal issues raised are highly relevant to the multi-disciplinary teams developing treatment strategies to preserve the fertility of prepubertal and adolescent boys who have a high risk of fertility loss due to ablative interventions, trauma or genetic pre-disposition.STUDY FUNDING/COMPETING INTERESTS:The work was funded by the European Society of Human Reproduction and Embryology (ESHRE). There were no conflicts of interest.

Rapid progress in the development of novel experimental strategies to generate fertile gametes from cryo-preserved ovarian and testicular tissue motivates oncologists to investigate ways in which gonadal tissue might be preserved. Childhood cancer patients remain the major pediatric group which can benefit from these techniques. Other potential candidates include patients with systemic diseases, which require gonadotoxic chemotherapy, patients undergoing gonadectomy, patients with Turner or Kleinefelter's syndrome, and boys with cryptorchid testes. This review aims to present an overview of the current state of knowledge in experimental germ stem cell transplantation in higher primates including humans, and the clinical risks and limitations related to such procedures in children. This area of research is discussed in the context of the potential future options that may become available for preserving fertility in boys and girls.

Background: We evaluated the body composition and its association with hypogonadism in adult male long-term acute lymphoblastic leukemia (ALL) survivors. Methods: The cohort included 49 long-term male ALL survivors and 55 age-matched healthy controls. Fat and lean mass was assessed by dual-energy X-ray absorptiometry; blood biochemistry was obtained for adipokines and testicular endocrine markers. Results: As compared with controls, the ALL survivors (median age 29 years, range 25-38), assessed 10-28 years after ALL diagnosis, had higher percentages of body (p < 0.05) and trunk fat mass (p < 0.05), and a lower body lean mass (p < 0.001). Survivors had significantly higher levels of leptin and adiponectin and lower levels of insulin-like growth factor-binding protein 3. Body fat mass and percent fat mass correlated with serum leptin and sex hormone-binding globulin (SHBG) levels. Altogether, 15% of the ALL survivors and 9% of age-matched controls were obese (BMI ≥30). Obese survivors more often had hypogonadism, had received testicular irradiation, and needed testosterone replacement therapy compared to nonobese survivors. Conclusion: At young adulthood, long-term male ALL survivors have significantly increased body adiposity despite normal weight and BMI. Potential indicators of increased adiposity included high leptin and low SHBG levels. Serum testicular endocrine markers did not correlate with body adiposity.

The physiological apoptosis that occurs in immature testis appears to be necessary for the maturation of this tissue. Thus, inhibition of the early apoptotic wave associated with the first round of spermatogenesis is followed by accumulation of spermatogonia and infertility later in life. To identify the cell types undergoing apoptosis in immature rat testis and to characterize the relationship between this apoptosis and progression of the first wave of spermatogenesis, sequential viable segments of seminiferous tubules from 8-, 18-, and 26-day-old rats were examined under a phase-contrast microscope. One novel observation was the existence of pronounced stage-specificity during the peak of apoptosis at the very early postnatal ages of 18 and 26 days. Increased apoptosis of pachytene spermatocytes in stages VII-VIII was the major feature that distinguished immature spermatogenesis from the corresponding adult process. The frequency of apoptosis among type A spermatogonia in immature stages IX-I was also elevated in comparison to the corresponding mature stages. The age-related peak of apoptosis was mediated by caspase 3; furthermore, stage-dependent expression of Bax in midpachytene spermatocytes was observed in the 18- and 26-day-old testis. These observations suggest that this Bax-regulated, caspase 3-mediated, increased apoptosis of midpachytene spermatocytes during the first wave of immature spermatogenesis represents a major difference in comparison to apoptosis occurring in the mature testis, and it may play an important regulatory role in establishing spermatogenesis in the rat testis.

Central nervous system (CNS) involvement in childhood acute myeloid leukemia (AML) can manifest as leukemic cells in the cerebrospinal fluid, a solid CNS tumor, or as neurological symptoms. We evaluated the presenting symptoms and neuroimaging findings in 33 of 34 children with AML and CNS involvement at diagnosis in the period 2000-2012 in Sweden, Finland, and Denmark. Imaging was performed in 22 patients, of whom 16 had CNS-related symptoms. Seven patients, including all but two with facial palsy, had mastoid cell opacification, considered an incidental finding. The frequent involvement of the mastoid bone with facial palsy warrants evaluation in larger series.

Treatment-related late toxicities after pediatric allogeneic hematopoietic SCT (allo-HSCT) are increasingly important as long-term survival has become an expected outcome for many transplanted children and adolescents. In a retrospective cohort study, we assessed long-term health outcomes in 204 allo-HSCT survivors transplanted in childhood or adolescence (20 years) between 1978 through 2000 after a median follow-up time of 12 (range 4-28) years. Data on conditioning regimen, adverse health events (AE) and growth and hormonal substitutions (hormone replacement therapies (HRTs)) were obtained from medical records. AEs were graded retrospectively according to Common Terminology Criteria for Adverse Events v3.0. Late deaths (⩾48 months after allo-HSCT) were evaluated separately. Multivariate analysis demonstrated that chronic GVHD (P0.000) and longer follow-up time (P0.05) correlated with AEs, whereas CY-based conditioning was inversely correlated (P0.002). TBI and longer follow-up duration predicted more severe AEs (P0.001 and P0.001, respectively). HRTs were more frequent after TBI. Diabetes type II, dyslipidemia and hypertension were detected in 9, 7 and 7% of the survivors, respectively. Late deaths (n=22) were most frequently due to pulmonary failure (n=7), followed by secondary malignancy (n=5). The occurrence of AEs after pediatric allo-HSCT is high and likely to increase during extended follow-up, particularly in patients who have received TBI.

Background With increased long-term survivors of childhood cancer patients, therapy-associated infertility has become one of the most common late side-effects and significantly affects their life-quality. Therefore, evaluation of anti-cancer agents on male reproduction and infertility prevention are urgently demanding. The proteasome inhibitor bortezomib has been launched in clinical trials for childhood cancers, however, its potential side effects on reproduction have so far been neither investigated experimentally nor reported in treated children. Thus the present study is designed to explore the impact of bortezomib on male reproductive function and to gain insights into how bortezomib exerts its adverse effects on man gonad, thereby providing pediatric oncologists relevant information. Methods 35 day-old male mice were treated with one 11-day cycle of bortezomib and then sacrificed 2 days, 45 days, or 6 months later. A mating study was performed in the group followed for 6 months, and their pups were analyzed on postnatal day 50. Serum follicle-stimulating hormone (FSH) and testicular testosterone levels were measured. Testicular morphology was evaluated by light- and electron microscopy, and the underlying mechanisms and pathways of testis damage were investigated. Results Testicular damage was visible already 2 days after stopping bortezomib and increased in severity by day 45. Then 80% of seminiferous tubules exhibited hypospermatogenesis with arrest at the levels of spermatogonia, spermatocytes and round spermatids. Germ cells were specifically targeted by bortezomib as evidenced by increased apoptosis mediated through activation of p53 and caspases. Even six months after the bortezomib treatment, testis weight, sperm concentration and seminiferous tubule length remained at a decreased level, indicating that spermatogenesis and tubular outgrowth could not fully recover. Combined with persistently increased serum levels of FSH in these mice, our results demonstrate that bortezomib can have long-term effects on testicular function, although fertility of bortezomib-exposed males remained and their offspring looked healthy. Conclusion Bortezomib treatment causes long-term gonadal dysfunction in male mice. Careful monitoring of gonadal function in male childhood cancer patients treated with bortezomib is thus strongly recommended.

Testicular dysfunction and infertility are of major concern in long-term survivors after allogeneic hematopoietic stem cell transplantation (HSCT). This study assesses predictive factors for very long-term testicular recovery after allogeneic HSCT in childhood and adolescence.Testicular volume, sperm production and long-term need of testosterone substitution were evaluated among 106 male survivors transplanted at Huddinge and Helsinki University Hospitals from 1978 through 2000, at a mean age of 8 ± 4.6 years (range 1-17). A mean ± SD of 13 ± 4.8 years (range 4-28) had elapsed since their HSCT and the mean age of the participants was 22 ± 6.0 years (range 12-42). An adult testicular volume was recorded in 74 patients at a mean age of 19 ± 3.3 years (range 14-36).Recipients conditioned with busulfan-based regimens or regimens containing only cyclophosphamide had significantly larger adult testicular volumes (mean volume 18 ml and 16 ml vs. 9 ml, P0.00001, respectively) and lower serum levels of FSH (mean 9 IU and 5 IU vs. 19 IU, P0.01 and 0.001, respectively) compared to those conditioned with total body irradiation (TBI). Multivariate analysis demonstrated that a non-leukemia diagnosis (P0.01) and adult testicular volume ≥ 15 ml (P0.03) positively impacted spermatogenetic recovery.A larger adult testicular volume, normal serum levels of FSH and spermatozoa detected in a majority of seminal fluids after busulfan-based or cyclophosphamide conditionings suggest very long-term recovery of spermatogenesis after chemotherapy-based regimens. A simple measurement of adult testicular volume may help predict spermatogenetic potential among pediatric HSCT survivors.

High-dose methotrexate (HD-MTX) is potentially nephrotoxic. The feasibility of novel biomarkers to indicate renal injury due to HD-MTX infusion was studied in children with acute lymphoblastic leukemia (ALL).Markers for glomerular and tubular injury were evaluated prospectively after HD-MTX infusion in 20 children with ALL. Plasma creatinine, cystatin C, and neutrophil gelatinase-associated lipocalin (NGAL) were measured 24-48 hr before MTX-infusion and 24, 36, 48, and 72 hr after starting the HD-MTX treatment, and thereafter daily until the MTX concentration was below 0.1 µmol/L. Urine NGAL, β2 -microglobulin, and creatinine concentrations as well as dipstick and urinalysis were performed at the same time points.In children with ALL, HD-MTX treatment at 5 g/m(2) over 24 hr was well tolerated and none of the patients developed significant glomerular or tubular dysfunction. The mean plasma cystatin C level increased significantly (P 0.001) from 0.83 mg/L at baseline to 0.94 mg/L at 36 hr after starting the HD-MTX treatment. The cystatin C concentration remained within reference range in all but two patients (10%). There was no significant change in plasma creatinine level during or after HD-MTX treatment, the values being normal in all patients. Plasma and urea NGAL did not increase during or after the HD-MTX treatment.Our results suggest that plasma cystatin C concentration alone is a sensitive marker to monitor renal function during and after HD-MTX infusion in pediatric ALL patients. Plasma or urine NGAL do not provide any further advantage in the follow-up of these patients.

We report the first large series (n = 596) of pediatric acute myeloid leukemia (AML) focusing on modal numbers (MN) from the population-based NOPHO-AML trials. Abnormal karyotypes were present in 452 cases (76%) and numerical aberrations were present in 40% (n = 237) of all pediatric AML. Among patients with an abnormal karyotype, the MN 46 was most common (n = 251; 56%) of which 36 (8%) were pseudodiploid with numerical aberrations, followed by MN 47 (n = 80; 18%) and MN 43-45 (n = 48; 8%). No cases had MN less than 43. Hyperdiploid AML with MN 48-65 comprised 11% of all cases and was associated with early onset (median age 2 years), female sex (57%), and a dominance of acute megakaryoblastic leukemia (AMKL) (29%). Hypodiploidy constituted 8% of all AML and was associated with older age (median age 9 years), male predominance (60%), FAB M2 (56%), and t(8;21)(q22;q22) (56%) with loss of sex chromosomes. Inferior outcome was observed for hypodiploid cases (5-year event-free survival 40% and 5-year overall survival 40%) but did not reach statistical significance. Chromosomes were gained in a nonrandom pattern, where chromosomes 8, 21, 19, and 6 were the most commonly gained. In conclusion, based on MNs, two cytogenetic subgroups with characteristic clinical features are described; hypodiploidy found in 8% and associated with high median age, male sex, t(8;21)(q22;q22), and FAB M2 and possibly associated with inferior outcome (P = 0.13), and hyperdiploidy with MN 48-65 in 11% associated with early onset, female sex, and AMKL.

Decreased linear growth is a common problem during childhood anticancer therapy. Although catch-up growth may occur, short stature is sometimes permanent. A macroscopic experimental study was performed to investigate the catch-up growth of body and craniofacial structures of growing rats subjected to the antineoplastic agent vincristine. A total of 150 Long-Evans/Turku strain rats were randomly divided into one of two treatment or control groups. A group of 10-d-old rats was given a single s.c. injection of 0.0375 mg/kg vincristine, while another treatment group of 30-d-old rats received three injections of 0.05 mg/kg vincristine. All rats were killed at the age of 100 d. Twelve different craniofacial dimensions, tibia and body length, and final weight were recorded. Female and male groups were analyzed separately. As an expression of catch-up growth, most of the body and craniofacial structures returned to the control level by 100 d of age. A clear sex-dependency was seen in the measurements which remained reduced so that females seemed to catch-up better than males. The timing of the first injection was found to be important for the catch-up growth in the neurocranial area.

ObjectiveThe aim of the study was to evaluate long-term ovarian function after allogeneic hematopoietic stem cell transplantation (HSCT) in childhood and adolescence.Subjects and methodsPredictive factors for ovarian function were evaluated among 92 adult or pubertal female survivors transplanted at Huddinge and Helsinki University Hospital during 1978–2000, at a mean age of 9±4.3 years (range 1–19). At the time of the study a mean±s.d. of 13±5.5 years (range 6–27) had elapsed since the HSCT and the mean age of the participants was 22±6.3 years (range 9–41).ResultsSpontaneous puberty based on breast development occurred in 40 and menarche in 30 of the 70 girls who were prepubertal at transplantation. Six out of 20 girls who received HSCT after initiation of pubertal development recovered their ovarian function. Younger age at HSCT, conditioning without total body irradiation (TBI), and a non-leukemia diagnosis predicted the spontaneous menarche. The incidence of menarche was higher after fractioned vs single fraction TBI (PPPPPPConclusionsPatients conditioned with TBI or Bu-based regimes are at high risk of ovarian failure. Intensive anti-leukemia therapy before HSCT including CRT especially among relapsed patients may further decrease the possibility of spontaneous menarche.

Children with acute lymphoblastic leukemia (ALL) have several risk factors for deep venous thromboses (DVTs) such as central venous catheters and asparaginase (ASP), related antithrombin (AT) deficiency. After introduction of a new standard and intermediate-risk ALL treatment protocol with prolonged continuous ASP treatment, two symptomatic DVTs in 10 patients were observed at the Children's Hospital, Helsinki, Finland. To prevent further thrombotic complications yet ensuring continuous exposure to ASP, an AT substitution strategy was adopted in Helsinki. The same ALL treatment protocol is used without AT substitution in the other Nordic countries. In this retrospective study, we describe the effect of prolonged ASP treatment on AT and fibrinogen levels in children without AT substitution in Stockholm, Sweden (n = 39) and the AT substitution in children with AT activity below 0.55 kIU/l in Helsinki (n = 36, intervention group). The intervention group is compared with children treated similarly earlier in Helsinki without AT substitution (n = 10). The median lowest AT activity during the ASP treatment without AT substitution was 0.55 kIU/l. Fibrinogen level of 1.0 g/l or less was found in 14% of all routine samples during the ASP treatment. In the intervention group, 23 (64%) received AT concentrate. Two (20%) children had symptomatic DVT before initiation of the AT substitution and two (6%) thereafter. We conclude that most children are exposed to low AT activity during ASP treatment predisposing to thrombosis. The effect of prophylactic AT substitution remains unclear.

Most cases of childhood leukemia are acute lymphoblastic leukemia, a small proportion being myelogenous leukemia. Chronic myelogenous leukemia is rare in children, whereas chronic lymphocytic leukemia is not encountered. The prognosis of childhood leukemia has improved considerably so that approximately 80 to 90% of those having lymphocytic leukemia and 60 to 70% of those having myelogenous leukemia will recover fully. The challenge is to develop new treatments for disease groups having a poor prognosis and on the other hand to lighten the treatments for leukemias having a good prognosis.