Gertjan J L Kaspers

VU University Medical Center, Amsterdamo, North Holland, Netherlands

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Publications (358)2023.28 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Pediatric acute myeloid leukemia (AML) is a heterogeneous disease, characterized by different collaborating karyotypic and molecular abnormalities, which are used in risk group stratification. In ∼20% of the pediatric AML cases a specific genetic aberration is still unknown. Minimally differentiated myeloid leukemia or FAB-type M0 is a rare morphological subtype of AML. The translocation t(10;17)(p15;q21) is described to be recurrent in minimally differentiated AML, but the involved genes and location of the breakpoints have so far not been identified. In this study, we show that this translocation results in an in-frame translocation fusing exon 12 of the tumor suppressor gene ZMYND11 to exon 3 of the chromatin protein MBTD1, encoding a protein of 1,054 amino acids, while the reciprocal fusion product is predicted to lack a productive start codon. Gene expression profiling of the leukemic cells showed high HOXA expression. ZMYND11, also known as BS69, is a tumor suppressor that specifically recognizes H3K36me3, which is linked to aberrant HOXA expression in leukemogenesis. Aberrant expression of the genes involved in this fusion may thus contribute to the HOXA-phenotype observed with gene expression profiling. © 2015 Wiley Periodicals, Inc.
    Genes Chromosomes and Cancer 11/2015; DOI:10.1002/gcc.22326 · 4.04 Impact Factor
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    ABSTRACT: Purpose: This study assessed cardiorespiratory fitness (CRF), physical activity (PA), and sedentary behavior (SB), as well as factors associated with these outcomes in children during or shortly after cancer treatment. Methods: Cross-sectionally, CRF data, obtained by the cardiopulmonary exercise test, and PA and SB data, obtained by an accelerometer, were assessed in children with cancer (8-18 years old). Linear regression models were used to determine associations between CRF, PA, or SB and patient characteristics. Results: Among 60 children with cancer, mean age 12.6 years, 35 boys, 28 % were during cancer treatment. CRF, reported as the z score of VO2peak, showed that 32 children had a VO2peak z score which was -2 below the predicted value. CRF was significantly associated with PA and SB: each additional activity count per minute resulted in 0.05 ml/kg/min VO2peak increase and each additional minute sedentary reduced VO2peak by 0.06 ml/kg/min. Multiple linear regression models of PA and SB showed that decreased activity was significantly associated with higher age, being fatigued, being during childhood cancer treatment (p < 0.001), or having a higher percentage of fat mass. The multiple linear regression model showed that lower CRF was significantly associated with increased fatigue, being during cancer treatment, having a higher percentage of fat mass, and lower belief of own athletic competence (p < 0.001). Conclusion: This study revealed that children during or shortly after cancer treatment have low CRF scores. The most inactive children had a higher fat mass, were fatigued, older, and during childhood cancer treatment. Unexpectedly, treatment-related factors showed no significant association with activity behavior.
    Supportive Care in Cancer 11/2015; DOI:10.1007/s00520-015-2993-1 · 2.36 Impact Factor
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    ABSTRACT: Purpose: This retrospective cohort study aimed to determine the predictive relevance of clinical characteristics, additional cytogenetic aberrations, and cKIT and RAS mutations, as well as to evaluate whether specific treatment elements were associated with outcomes in pediatric t(8;21)-positive patients with acute myeloid leukemia (AML). Patients and methods: Karyotypes of 916 pediatric patients with t(8;21)-AML were reviewed for the presence of additional cytogenetic aberrations, and 228 samples were screened for presence of cKIT and RAS mutations. Multivariable regression models were used to assess the relevance of anthracyclines, cytarabine, and etoposide during induction and overall treatment. End points were the probability of achieving complete remission, cumulative incidence of relapse (CIR), probability of event-free survival, and probability of overall survival. Results: Of 838 patients included in final analyses, 92% achieved complete remission. The 5-year overall survival, event-free survival, and CIR were 74%, 58%, and 26%, respectively. cKIT mutations and RAS mutations were not significantly associated with outcome. Patients with deletions of chromosome arm 9q [del(9q); n = 104] had a lower probability of complete remission (P = .01). Gain of chromosome 4 (+4; n = 21) was associated with inferior CIR and survival (P < .01). Anthracycline doses greater than 150 mg/m(2) and etoposide doses greater than 500 mg/m(2) in the first induction course and high-dose cytarabine 3 g/m(2) during induction were associated with better outcomes on various end points. Cumulative doses of cytarabine greater than 30 g/m(2) and etoposide greater than 1,500 mg/m(2) were associated with lower CIR rates and better probability of event-free survival. Conclusion: Pediatric patients with t(8;21)-AML and additional del(9q) or additional +4 might not be considered at good risk. Patients with t(8;21)-AML likely benefit from protocols that have high doses of anthracyclines, etoposide, and cytarabine during induction, as well as from protocols comprising cumulative high doses of cytarabine and etoposide.
    Journal of Clinical Oncology 11/2015; DOI:10.1200/JCO.2015.61.1947 · 18.43 Impact Factor
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    ABSTRACT: Methotrexate (MTX), a folate antagonist which blocks de novo nucleotide biosynthesis and DNA replication, is an anchor drug in acute lymphoblastic leukemia (ALL) treatment. However, drug resistance is a primary hindrance to curative chemotherapy in leukemia and its molecular mechanisms remain poorly understood. We have recently shown that impaired folylpolyglutamate synthetase (FPGS) splicing possibly contributes to the loss of FPGS activity in MTX-resistant leukemia cell line models and adult leukemia patients. However, no information is available on the possible splicing alterations in FPGS in pediatric ALL. Here, using a comprehensive PCR-based screen we discovered and characterized a spectrum of FPGS splicing alterations including exon skipping and intron retention, all of which proved to frequently emerge in both pediatric and adult leukemia patient specimens. Furthermore, an FPGS activity assay revealed that these splicing alterations resulted in loss of FPGS function. Strikingly, pulse-exposure of leukemia cells to antifolates and other chemotherapeutics markedly enhanced the prevalence of several FPGS splicing alterations in antifolate-resistant cells, but not in their parental antifolate-sensitive counterparts. These novel findings suggest that an assortment of deleterious FPGS splicing alterations may constitute a mechanism of antifolate resistance in childhood ALL. Our findings have important implications for the rational overcoming of drug resistance in individual leukemia patients. This article is protected by copyright. All rights reserved.
    International Journal of Cancer 11/2015; DOI:10.1002/ijc.29919 · 5.09 Impact Factor
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    ABSTRACT: Objective: Although survival rates in childhood cancer have improved, prevention and reduction of late effects remain important. This study evaluates the effects of a combined physical exercise and psychosocial intervention on health-related quality of life (HrQoL) and psychosocial functioning in childhood cancer patients. Methods: In this multicenter randomized controlled trial, cancer patients (aged 8-18 years) and their parents filled in questionnaires on HrQoL, depressive symptoms, behavioral problems, and self-esteem. Measurements were conducted at baseline, shortly after the 12-week intervention period and 12 months after baseline. Generalized estimating equations analyses were performed to assess short-term and long-term psychosocial effects. Results: Of the 174 eligible patients, 68 (39.1%) participated. The intervention group consisted of 30 participants at baseline [mean age 13.0 (SD 3.0) years; 53% male], 26 at short-term and 22 at long-term follow-up. The 'care as usual' control group consisted of 38 participants at baseline [mean age 12.6 (SD 3.1) years; 53% male], 33 at short-term and 31 at long-term follow-up. Overall, the intervention did not improve psychosocial functioning and HrQoL. According to parent-proxy reports, the intervention leads to a greater improvement on pain-related HrQoL on both the short (β = 13.4; 95% CI: 3.0; 23.8) and long term (β = 13.0; 95% CI: 1.6; 24.4) and to greater improvement on procedural anxiety immediately after the intervention (β = 12.6; 95% CI: 1.9; 23.3). Conclusion: A combined physical and psychosocial training for children with cancer did not have effects on HrQoL or psychosocial functioning, with exception of modest positive effects on parent-reported pain and procedural anxiety Copyright © 2015 John Wiley & Sons, Ltd.
    Psycho-Oncology 10/2015; DOI:10.1002/pon.4016 · 2.44 Impact Factor
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    ABSTRACT: Background: More than 90% of patients with diffuse intrinsic pontine glioma (DIPG) will die within 2 years of diagnosis. Patients deteriorate rapidly during the disease course, which severely impairs their quality of life. To date, no specific research on this clinically important subject has been conducted. This study aimed to compile an inventory of symptoms experienced, interventions applied, and current service provision in end-of-life care for DIPG. Methods: We performed a retrospective cohort study of children with DIPG, aged 0-18 years, who received treatment under the care of 2 London hospitals. Symptoms, interventions, and services applied during the 12 weeks before death were analyzed. In addition, we conducted a global questionnaire-study among health care professionals. Results: In more than 78% of DIPG patients, problems concerning mobility, swallowing, communication, consciousness, and breathing arose during end-stage disease. Supportive drugs were widely prescribed. The use of medical aids was only documented in <15% of patients. Palliative and end-of-life care was mostly based on the health care professional's experience; only 21% of the questionnaire respondents reported to have a disease-specific palliative care guideline available. Conclusions: This research assessed the current state of palliative and end-of-life care for children with DIPG. Our results show the variability and complexity of symptoms at end-stage disease and the current lack of disease-specific guidelines for this vulnerable group of patients. This first descriptive paper is intended to act as a solid basis for developing an international clinical trial and subsequent guideline to support high-quality palliative and end-of-life care.
    Neuro-Oncology 10/2015; DOI:10.1093/neuonc/nov250 · 5.56 Impact Factor
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    ABSTRACT: The first cohorts to survive childhood lymphoid malignancies treated with cranial irradiation are now aging into adulthood, and concerns are growing about the development of radiotherapy-induced cognitive deficits in the aging brain. These deficits are hypothesized to increase over time. Their impact on daily functioning of older survivors, and the accompanying need for interventions, should be anticipated. By describing a detailed profile of executive function deficits and their associations with age, specific targets for neuropsychological intervention can be identified. Fifty survivors of childhood lymphoid malignancies and 58 related controls were assessed with the Amsterdam Neuropsychological Tasks program. The survivors were on average 31.1 (4.9) years old, treated with 22.5 (6.8) Gy cranial irradiation, and examined on average 25.5 (3.1) years after diagnosis. The survivors showed significantly decreased response speed, irrespective of the task at hand. Furthermore, we found deficits in working memory capacity, inhibition, cognitive flexibility, executive visuomotor control, attentional fluctuations, and sustained attention. Older age was associated with poorer performance on executive visuomotor control and inhibition. On executive visuomotor control, 50% of female survivors performed more than 1.5 SD below average, versus 15.4% of male survivors. The combination of visuospatial working memory problems and decreasing executive visuomotor control could result in difficulty with learning new motor skills at older ages, like walking with a cane. Deterioration of executive control and inhibition may result in decreased behavioral and emotional regulation in aging survivors. Especially the deficiency in executive visuomotor control in female survivors should be considered for (prophylactic) intervention. ( JINS , 2015, 21 , 1–13)
    Journal of the International Neuropsychological Society 09/2015; 21(9):1-13. DOI:10.1017/S1355617715000788 · 2.96 Impact Factor
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    ABSTRACT: Diagnosis, treatment, response monitoring, and outcome of pediatric acute myeloid leukemia (AML) have made enormous progress during the past decades. Because AML is a rare type of childhood cancer, with an incidence of approximately seven occurrences per 1 million children annually, national and international collaborative efforts have evolved. This overview describes these efforts and includes a summary of the history and contributions of each of the main collaborative pediatric AML groups worldwide. The focus is on translational and clinical research, which includes past, current, and future clinical trials. Separate sections concern acute promyelocytic leukemia, myeloid leukemia of Down syndrome, and relapsed AML. A plethora of novel antileukemic agents that have emerged, including new classes of drugs, are summarized as well. Finally, an important aspect of the treatment of pediatric AML-supportive care-and late effects are discussed. The future is bright, with a wide range of emerging innovative therapies and with more and more international collaboration that ultimately aim to cure all children with AML, with fewer adverse effects and without late effects.
    Journal of Clinical Oncology 08/2015; 33(27). DOI:10.1200/JCO.2015.62.8289 · 18.43 Impact Factor
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    ABSTRACT: Use of complementary and alternative medicine (CAM) is common among patients with childhood cancer. Health-care providers (HCP) should address this need properly. Geographical and cultural differences seem likely. This study explores perspectives on CAM of HCP involved in the care of children with cancer in Netherlands and Indonesia. Health beliefs, components of CAM, encouraging or discouraging CAM, and knowledge about CAM were assessed. We conducted a cross-sectional study using semi-structured questionnaires at a Dutch and Indonesian academic hospital. A total of 342 HCP participated: 119 Dutch (response rate 80%) and 223 Indonesian (response rate 87%). Chemotherapy can cure cancer according to more Dutch than Indonesian HCP (87% vs. 53% respectively, P < 0.001). Combination of chemotherapy and CAM is the best way to cure cancer according to more Indonesian than Dutch HCP (45% vs. 25%, P < 0.001). Dutch and Indonesian HCP recommend and discourage CAM use differently. Most Dutch (77%) and Indonesian HCP (84%) consider their knowledge about CAM to be inadequate (P = ns). Fewer Dutch doctors than other HCP want to learn more about CAM (51% vs. 76%, P = 0.007), whereas there is no significant difference in eagerness to learn about CAM between Indonesian doctors (64%) and other HCP (72%). Indonesian HCP have more positive views about CAM than their Dutch colleagues. Both Dutch and Indonesian HCP consider their knowledge about CAM to be inadequate. Therefore, education programs about CAM tailored to the needs of HCP are recommended, knowing that CAM is used frequently. Pediatr Blood Cancer © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.
    Pediatric Blood & Cancer 08/2015; DOI:10.1002/pbc.25689 · 2.39 Impact Factor
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    ABSTRACT: At the government, hospital, and health-care provider level, corruption plays a major role in health-care systems in Africa. The returns on health investments of international financial institutions, health organisations, and donors might be very low when mismanagement and dysfunctional structures of health-care systems are not addressed. More funding might even aggravate corruption. We discuss corruption and its effects on cancer care within the African health-care system in a sociocultural context. The contribution of high-income countries in stimulating corruption is also described. Corrupt African governments cannot be expected to take the initiative to eradicate corruption. Therefore, international financial institutions, health organisations, and financial donors should use their power to demand policy reforms of health-care systems in Africa troubled by the issue of corruption. These modifications will ameliorate the access and quality of cancer care for patients across the continent, and ultimately improve the outcome of health care to all patients. Copyright © 2015 Elsevier Ltd. All rights reserved.
    The Lancet Oncology 08/2015; 16(8):e394-404. DOI:10.1016/S1470-2045(15)00163-1 · 24.69 Impact Factor

  • Cancer Research 08/2015; 75(15 Supplement):4437-4437. DOI:10.1158/1538-7445.AM2015-4437 · 9.33 Impact Factor
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    ABSTRACT: Background: Retinoblastoma is a pediatric eye cancer associated with RB1 loss or MYCN amplification (RB1+/+MYCNA). There are controversies concerning the existence of molecular subtypes within RB1−/− retinoblastoma. To test whether these molecular subtypes exist, we performed molecular profiling. Methods: Genome-wide mRNA expression profiling was performed on 76 primary human retinoblastomas. Expression profiling was complemented by genome-wide DNA profiling and clinical, histopathological, and ex vivo drug sensitivity data. Findings: RNA and DNA profiling identified major variability between retinoblastomas. While gene expression differences between RB1+/+MYCNA and RB1−/− tumors seemed more dichotomous, differences within the RB1−/− tumors were gradual. Tumors with high expression of a photoreceptor gene signature were highly differentiated, smaller in volume and diagnosed at younger age compared with tumors with low photoreceptor signature expression. Tumors with lower photoreceptor expression showed increased expression of genes involved in M-phase and mRNA and ribosome synthesis and increased frequencies of somatic copy number alterations. Interpretation: Molecular, clinical and histopathological differences between RB1−/− tumors are best explained by tumor progression, reflected by a gradual loss of differentiation and photoreceptor expression signature. Since copy number alterations were more frequent in tumors with less photoreceptorness, genomic alterations might be drivers of tumor progression. Research in context: Retinoblastoma is an ocular childhood cancer commonly caused by mutations in the RB1 gene. In order to determine optimal treatment, tumor subtyping is considered critically important. However, except for very rare retinoblastomas without an RB1 mutation, there are controversies as to whether subtypes of retinoblastoma do exist. Our study shows that retinoblastomas are highly diverse but rather than reflecting distinct tumor types with a different etiology, our data suggests that this diversity is a result of tumor progression driven by cumulative genetic alterations. Therefore, retinoblastomas should not be categorized in distinct subtypes, but be described according to their stage of progression.
    07/2015; 2(7):660-670. DOI:10.1016/j.ebiom.2015.06.022
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    ABSTRACT: Methotrexate (MTX) eradicates leukemic cells by disrupting de novo nucleotide biosynthesis and DNA replication, resulting in cell death. Since its introduction in 1947, MTX-containing chemotherapeutic regimens have proven instrumental in achieving curative effects in acute lymphoblastic leukemia (ALL). However, drug resistance phenomena pose major obstacles to efficacious ALL chemotherapy. Moreover, clinically relevant molecular mechanisms underlying chemoresistance remain largely obscure. Several alterations in MTX metabolism, leading to impaired accumulation of this cytotoxic agent in tumor cells, have been classified as determinants of MTX resistance. However, the relation between MTX resistance and long-term clinical outcome of ALL has not been shown previously. We have collected clinical data for 235 childhood ALL patients, for whom samples taken at the time of diagnosis were also broadly characterized with respect to MTX resistance. This included measurement of concentrations of MTX polyglutamates in leukemic cells, mRNA expression of enzymes involved in MTX metabolism (FPGS, FPGH, RFC, DHFR, and TS), MTX sensitivity as determined by the TS inhibition assay, and FPGS activity. Herein we demonstrate that higher accumulation of long-chain polyglutamates of MTX is strongly associated with better overall (10-year OS: 90.6 vs 64.1 %, P = 0.008) and event-free survival (10-year EFS: 81.2 vs 57.6 %, P = 0.029) of ALL patients. In addition, we assessed both the association of several MTX resistance-related parameters determined in vitro with treatment outcome as well as clinical characteristics of pediatric ALL patients treated with MTX-containing combination chemotherapy. High MTX sensitivity was associated with DNA hyperdiploid ALL (P < 0.001), which was linked with increased MTX accumulation (P = 0.03) and elevated reduced folate carrier (RFC) expression (P = 0.049) in this subset of ALL patients. TEL-AML1 fusion was associated with increased MTX resistance (P = 0.023). Moreover, a low accumulation of MTX polyglutamates was observed in MLL-rearranged and TEL-AML1 rearranged ALL (P < 0.05). These findings emphasize the central role of MTX in ALL treatment thereby expanding our understanding of the molecular basis of clinical differences in treatment response between ALL individuals. In particular, the identification of patients that are potentially resistant to MTX at diagnosis may allow for tailoring novel treatment strategies to individual leukemia patients.
    Journal of Hematology & Oncology 05/2015; 8(1):61. DOI:10.1186/s13045-015-0158-9 · 4.81 Impact Factor
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    ABSTRACT: Unlabelled: Loss of ephrin receptor (EphB1) expression may associate with aggressive cancer phenotypes; however, the mechanism of action remains unclear. To gain detailed insight into EphB1 function in acute myelogenous leukemia (AML), comprehensive analysis of EphB1 transcriptional regulation was conducted. In AML cells, EphB1 transcript was inversely correlated with EphB1 promoter methylation. The presence of EphB1 allowed EfnB1 ligand-mediated p53 DNA binding, leading to restoration of the DNA damage response (DDR) cascade by the activation of ATR, Chk1, p53, p21, p38, CDK1(tyr15), and Bax, and downregulation of HSP27 and Bcl2. Comparatively, reintroduction of EphB1 expression in EphB1-methylated AML cells enhanced the same cascade of ATR, Chk1, p21, and CDK1(tyr15), which consequently enforced programmed cell death. Interestingly, in pediatric AML samples, EphB1 peptide phosphorylation and mRNA expression were actively suppressed as compared with normal bone marrow, and a significant percentage of the primary AML specimens had EphB1 promoter hypermethylation. Finally, EphB1 repression associated with a poor overall survival in pediatric AML. Combined, the contribution of EphB1 to the DDR system reveals a tumor-suppressor function for EphB1 in pediatric AML. Implications: The tumor-suppressor function of EphB1 is clinically relevant across many malignancies, suggesting that EphB1 is an important regulator of common cancer cell transforming pathways.
    Molecular Cancer Research 05/2015; 13(6). DOI:10.1158/1541-7786.MCR-14-0660-T · 4.38 Impact Factor
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    ABSTRACT: Development of relapse remains a problem for further improvements in the survival of pediatric AML patients. While virtually all patients show a good response to initial treatment, more patients respond poorly when treated at relapse. The cellular characteristics of leukemic blast cells that allow survival of initial treatment, relapse development and subsequent resistance to salvage treatment remain largely elusive. Therefore, we studied if leukemic blasts at relapse biologically resemble their initial diagnosis counterparts. We performed microarray gene expression profiling on paired initial and relapse samples of 23 pediatric AML patients. In 11 out of 23 patients, gene expression profiles of initial and corresponding relapse samples end up in different clusters in unsupervised analysis, indicating altered gene expression profiles. In addition, shifts in type I/II mutational status were found in 5 of these 11 patients, while shifts were found in 3 of the remaining 12 patients. Although differentially expressed genes varied between patients, they were commonly related to hematopoietic differentiation, encompassed genes involved in chromatin remodeling and showed associations with similar transcription factors. The top five were CEBPA, GFI1, SATB1, KLF2 and TBP . In conclusion, the leukemic blasts at relapse are biologically different from their diagnosis counterparts. These differences may be exploited for further development of novel treatment strategies.
    PLoS ONE 04/2015; 10(4):e0121730. DOI:10.1371/journal.pone.0121730 · 3.23 Impact Factor
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    ABSTRACT: Placement of a totally implantable venous access device in children with cancer often leads to hypertrophic scars after its removal. This study investigates whether the use of silicone gel sheets has a beneficial effect on scar outcome in children with cancer. In a three-arm randomized controlled trial, the effects of use of silicone gel sheets for 2 and 6 months were assessed and compared with no intervention in children with cancer after removal of the totally implantable venous access device. Silicone gel sheets were first administered 14 days after surgery. The 1-year follow-up included measurements at seven time points. Next to scar size assessment, the modified Vancouver Scar Scale was used to assess scar outcome. Thirty-six children participated. For hypertrophy, no significant differences were found between the two intervention groups and the control group. However, at 1-year follow-up, the 2-month application group showed significantly smaller scars compared with the group receiving silicone gel sheet treatment for 6 months (p = 0.04), but not when compared with the control group (p = 0.22). Longitudinal multilevel analyses could not confirm these findings and showed no significant intervention effects on both outcomes. This study provides no strong evidence to support the use of silicone gel sheets after totally implantable venous access device removal in children with cancer. There seems to be a small benefit for scar width with application for 2 months. However, for hypertrophy, the scar outcome shows no significant difference between the control group and the 2-month and 6-month treatment groups. Therapeutic, I.
    Plastic and Reconstructive Surgery 04/2015; 135(4):1086-1094. DOI:10.1097/PRS.0000000000001053 · 2.99 Impact Factor
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    ABSTRACT: The purpose of this study is to explore the applicability of a psychosocial intervention in childhood cancer patients. This individualized structured psychosocial program to enhance social-emotional functioning and coping with disease-related effects includes six sessions for children and two sessions for parents. This program was part of a combined intervention with physical exercise. Questionnaires are used to evaluate completion of the psychosocial intervention, coping and satisfaction with the psychosocial intervention by patients and psychologists, and ranking of the individual topics by patients, parents, and psychologists. Of the 30 patients (mean age 13.0 (SD 3.0); 53.3 % male; 30 % still on treatment) who participated in the psychosocial intervention, two dropped out due to medical complications and one due to lack of time; 90 % completed the psychosocial intervention. Overall, patients liked participation in the intervention (4.2 on a 5-point scale; SD 0.8) and were positive about the psychologists (8.1 on a 10-point scale; SD 1.3). Psychologists rated the intervention on several points (e.g., clarity of the manual and content of the intervention), and mean scores ranged from 7.1 (SD 1.1) to 8.6 (SD 0.9) on 10-point scales. Minor adaptations were suggested by patients and psychologists, including customizing according to age and a more patient-tailored approach. This psychosocial intervention for childhood cancer patients appears to be applicable. Future studies need to establish whether this intervention combined with a physical exercise intervention actually improves psychosocial functioning of childhood cancer patients. When proven effective, this combined intervention can be offered to childhood cancer patients and may enhance their physical health and quality of life.
    Supportive Care Cancer 01/2015; DOI:10.1007/s00520-014-2576-6 · 2.36 Impact Factor
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    ABSTRACT: Over the past decade, the proteasome inhibitor bortezomib (Velcade) has not only gained a cornerstone position in the treatment of hematological malignancies, particularly multiple myeloma and mantle cell lymphoma, but also in experimental therapeutics of acute leukemia. However, the therapeutic efficacy of bortezomib is hampered by the emergence of acquired resistance, for which multifactorial mechanisms have been identified. This review summarizes the current status of the molecular mechanisms underlying resistance to proteasome inhibitors that emerged in preclinical therapeutic studies, and discusses these findings in the clinical perspective of novel therapeutic modalities of hematological malignancies. The specific topics that will be addressed in the current review include the recently established mechanisms of resistance to proteasome inhibitors: the role of constitutive and immunoproteasomes, mutations in proteasome subunits, unfolded protein response, XBP1 and MARCKS proteins, multidrug efflux transporters, aggresomes and autophagy, as well as the impact of pro-survival signaling pathways and bone marrow microenvironment. The growing knowledge of the determinants that confer bortezomib resistance and/or toxicity has provided the basis for the rational development of second generation proteasome inhibitors, some of which were recently approved or that are undergoing clinical evaluation as novel strategies to overcome bortezomib resistance as well as to enhance clinical therapeutic efficacy along with minimal side effects. Collectively, these combined approaches should enhance therapeutic efficacy and outcome in patients with hematological malignancies.
    Drug Resistance Updates 12/2014; 18. DOI:10.1016/j.drup.2014.12.001 · 9.12 Impact Factor
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    ABSTRACT: Background Wilms tumour postoperative chemotherapy is ideally stratified according to the pathologist's assessment of tumour stage and risk classification (tumour type). In sub-Saharan Africa results are often not available in time to influence therapy and in Malawi surgical staging has been used to stratify postoperative chemotherapy. Here we compare the results from surgical and both local pathology and central pathology review.ProcedureChildren diagnosed with a Wilms tumour in Blantyre, Malawi between 2007 and 2011 were included if they had a nephrectomy and the pathology slides were available. All tumour specimens were assessed in three different ways: the local surgeon documented the surgical stage of the tumour, and the risk classification and pathology stage were assessed both by the local pathologist and by a SIOP central review pathologist in Europe.ResultsFifty patients had complete data available and were included in the analyses. Tumour risk classification differed between the local and central pathology review in only two patients (4%). Using central pathology review as the gold standard 60% of patients received the correct postoperative chemotherapy treatment based on surgical staging and 84% based on the local pathology stage and risk classification.Conclusion Local pathology capacity building is needed to enable timely assessment and reporting. Pediatr Blood Cancer © 2014 Wiley Periodicals, Inc.
    Pediatric Blood & Cancer 12/2014; 61:2180-2184. DOI:10.1002/pbc.25138 · 2.39 Impact Factor
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    ABSTRACT: Children with and after cancer are found to have a decreased physical fitness, frequently resulting in decreased physical functioning. The gold standard test for assessing aerobic fitness, a component of physical fitness, is the respiratory gas analyses--based cardiopulmonary exercise test (CPET). However, equipment for gas analysis is often unavailable in local physical therapy centres and non--university hospitals. The Steep Ramp Test (SRT), is a cycle ergometer test with a fast increase in workload, a short duration, and does not require respiratory gas analysis equipment. The aim of this study was to compare the results of the CPET and the SRT, in children with cancer, and to assess whether the SRT can be used for aerobic fitness assessment in clinical practice in this population. This study is a cross--sectional assessment using baseline data of a randomized controlled trial. The study was performed in a hospital setting. Sixty--one children (mean age 12.9 years; 33 boys) with cancer were included in the analysis; 16 children were on non--intensive chemotherapy treatment, 45 were in the first year thereafter. Participants performed both the SRT and the CPET on a cycle ergometer with respiratory gas analysis. Data of the two tests were compared and regression analyses were performed. CPET test results revealed a higher impact on the cardiovascular system, as shown by higher peak ventilation (47.8 versus 52.0 Litres per min) and peak heart rates (173 versus 191 beats per min), compared to the SRT. In addition, the test time was significantly longer (90 s versus 390 s). Yet, the primary outcome of the SRT (peak work rate) was able to reliably estimate the peak oxygen uptake of the CPET. The peak oxygen uptake was comparable between the SRT and the CPET, although the peak work rate was significantly higher during the SRT. This study showed that the SRT is a valid instrument to assess aerobic fitness in children with cancer. The SRT is less time consuming and can be performed without gas analysis in a non--clinical setting, making it less demanding for children.
    European journal of physical and rehabilitation medicine 11/2014; 51(5). · 1.90 Impact Factor

Publication Stats

7k Citations
2,023.28 Total Impact Points


  • 2002-2015
    • VU University Medical Center
      • • Department of Clinical Genetics
      • • Department of Pediatrics
      • • Department of Orthopedic Surgery
      • • Department of Haematology
      Amsterdamo, North Holland, Netherlands
    • University of Hamburg
      Hamburg, Hamburg, Germany
    • Karmanos Cancer Institute
      Detroit, Michigan, United States
  • 1993-2014
    • VU University Amsterdam
      • Department of Pediatric Hematology/Oncology
      Amsterdamo, North Holland, Netherlands
  • 2013
    • University Medical Center Utrecht
      Utrecht, Utrecht, Netherlands
    • National Heart, Lung, and Blood Institute
      • Hematology Branch
      Maryland, United States
  • 2006-2013
    • Dutch Childhood Oncology Group
      Rotterdam, South Holland, Netherlands
  • 2011
    • Leiden University Medical Centre
      • Department of Pediatrics
      Leiden, South Holland, Netherlands
  • 2009-2010
    • Erasmus MC
      Rotterdam, South Holland, Netherlands
    • University of Groningen
      Groningen, Groningen, Netherlands
    • St. Jude Medical
      Little Canada, Minnesota, United States
    • Aarhus University Hospital
      • Department of Pediatrics
      Aarhus, Central Jutland, Denmark
  • 2008-2009
    • Charles University in Prague
      • Department of Paediatric Haematology and Oncology (2. LF)
      Praha, Praha, Czech Republic
    • Università degli Studi di Milano-Bicocca
      Milano, Lombardy, Italy
  • 2003
    • Universität Ulm
      Ulm, Baden-Württemberg, Germany
    • Kent Hospital
      Warwick, Rhode Island, United States
  • 1993-2000
    • University of Amsterdam
      • Department of Paediatrics
      Amsterdamo, North Holland, Netherlands
  • 1995
    • Erasmus Universiteit Rotterdam
      Rotterdam, South Holland, Netherlands
  • 1994
    • Post University
      Post, Texas, United States