Irinotecan and temozolomide in combination with dasatinib and rapamycin versus irinotecan and temozolomide for patients with relapsed or refractory neuroblastoma (RIST-rNB-2011): a multicentre, open-label, randomised, controlled, phase 2 trial.

BACKGROUND: Neuroblastoma is the most common extracranial solid tumour in children. Relapsed or refractory neuroblastoma is associated with a poor outcome. We assessed the combination of irinotecan-temozolomide and dasatinib-rapamycin (RIST) in patients with relapsed or refractory neuroblastoma. METHODS: The multicentre, open-label, randomised, controlled, phase 2, RIST-rNB-2011 trial recruited from 40 paediatric oncology centres in Germany and Austria. Patients aged 1-25 years with high-risk relapsed (defined as recurrence of all stage IV and MYCN amplification stages, after response to treatment) or refractory (progressive disease during primary treatment) neuroblastoma, with Lansky and Karnofsky performance status at least 50%, were assigned (1:1) to RIST (RIST group) or irinotecan-temozolomide (control group) by block randomisation, stratified by MYCN status. We compared RIST (oral rapamycin [loading 3 mg/m2 on day 1, maintenance 1 mg/m2 on days 2-4] and oral dasatinib [2 mg/kg per day] for 4 days with 3 days off, followed by intravenous irinotecan [50 mg/m2 per day] and oral temozolomide [150 mg/m2 per day] for 5 days with 2 days off; one course each of rapamycin-dasatinib and irinotecan-temozolomide for four cycles over 8 weeks, then two courses of rapamycin-dasatinib followed by one course of irinotecan-temozolomide for 12 weeks) with irinotecan-temozolomide alone (with identical dosing as experimental group). The primary endpoint of progression-free survival was analysed in all eligible patients who received at least one course of therapy. The safety population consisted of all patients who received at least one course of therapy and had at least one post-baseline safety assessment. This trial is registered at ClinicalTrials.gov, NCT01467986, and is closed to accrual. FINDINGS: Between Aug 26, 2013, and Sept 21, 2020, 129 patients were randomly assigned to the RIST group (n=63) or control group (n=66). Median age was 5·4 years (IQR 3·7-8·1). 124 patients (78 [63%] male and 46 [37%] female) were included in the efficacy analysis. At a median follow-up of 72 months (IQR 31-88), the median progression-free survival was 11 months (95% CI 7-17) in the RIST group and 5 months (2-8) in the control group (hazard ratio 0·62, one-sided 90% CI 0·81; p=0·019). Median progression-free survival in patients with amplified MYCN (n=48) was 6 months (95% CI 4-24) in the RIST group versus 2 months (2-5) in the control group (HR 0·45 [95% CI 0·24-0·84], p=0·012); median progression-free survival in patients without amplified MYCN (n=76) was 14 months (95% CI 9-7) in the RIST group versus 8 months (4-15) in the control group (HR 0·84 [95% CI 0·51-1·38], p=0·49). The most common grade 3 or worse adverse events were neutropenia (54 [81%] of 67 patients given RIST vs 49 [82%] of 60 patients given control), thrombocytopenia (45 [67%] vs 41 [68%]), and anaemia (39 [58%] vs 38 [63%]). Nine serious treatment-related adverse events were reported (five patients given control and four patients given RIST). There were no treatment-related deaths in the control group and one in the RIST group (multiorgan failure). INTERPRETATION: RIST-rNB-2011 demonstrated that targeting of MYCN-amplified relapsed or refractory neuroblastoma with a pathway-directed metronomic combination of a multkinase inhibitor and an mTOR inhibitor can improve progression-free survival and overall survival. This exclusive efficacy in MYCN-amplified, relapsed neuroblastoma warrants further investigation in the first-line setting. FUNDING: Deutsche Krebshilfe.

MicroRNA-profiling of miR-371~373- and miR-302/367-clusters in serum and cerebrospinal fluid identify patients with intracranial germ cell tumors.

PURPOSE: Intracranial germ cell tumors (iGCT) comprise germinoma and non-germinoma. Their diagnosis predominantly relies on biopsy as only one-fifth of patients present with elevated biomarkers (AFP/ß-HCG) in serum or cerebrospinal fluid (CSF). MicroRNAs (miR/miRNA) have emerged as non-invasive biomarkers in extracranial GCT and may potentially facilitate non-invasive diagnosis in iGCT. METHODS: We analyzed eight miRNAs in serum and CSF from the miR-371~373- and miR-302/367-clusters and four miRNAs differentially expressed in iGCT tissue (miR-142-5p/miR-146a-5p/miR-335-5p/miR-654-3p) from eight iGCT patients (age 10-33 years) and 12 control subjects by pre-amplified RT-qPCR. MiR-30b-5p (serum) and miR-204-5p (CSF) acted as reference genes. ΔCt-values were expressed as [Formula: see text] after standardization against controls. RESULTS: Between iGCT and control patients' serum ΔCt-values of miR-371a-3p (p = 0.0159), miR-372-3p (p= 0.0095, miR-367 (p = 0.0190), miR-302a (p = 0.0381) and miR-302d-3p (p = 0.0159) differed significantly. Discriminatory pattern in CSF was similar to serum as miR-371a (p = 0.0286), miR-372-3p (p = 0.0028), miR-367-3p (p = 0.0167) and miR-302d-3p (p = 0.0061) distinguished between patients and controls. Abundant [Formula: see text] levels of each of these miRNAs were found across all serum and CSF samples including biomarker-negative patients. CONCLUSION: With the largest data set so far, we underline the suitability of miR-371a, miR-372, miR-367 and miR-302d in serum and CSF for diagnosis of iGCT, particularly in biomarker-negative germinoma. Diagnosis of iGCT by miRNA analysis is a feasible and valid approach, particularly as serum can be readily obtained by a less invasive procedure. MiRNA analysis may discriminate iGCT from other tumors with similar radiological findings and may allow to monitor response to therapy as well as early relapse during follow-up.

The PI3K inhibitor pictilisib and the multikinase inhibitors pazopanib and sorafenib have an impact on Rac1 level and migration of medulloblastoma in vitro.

Metastatic disease is the leading cause of death in children suffering from medulloblastoma and a major treatment challenge. The evidence of leptomeningeal dissemination defines the most aggressive tumours and is associated with increased mortality; thus, inhibition of migration as a factor involved in the process of metastatic disease is fundamental for the treatment and prevention of metastatic dissemination. Targeting the small Rho GTPases Rac1 has been shown to effectively impair medulloblastoma cell migration in vitro. Yet clinically applicable selective Rac1 inhibitors are still lacking. In view of the pertinent oncogenic role of the PI3K signalling cascade and tyrosine kinase-mediated signalling pathways in medulloblastoma, we explored clinically available targeted therapeutics to this effect. Here, we show that Rac1 is expressed in both the cytoplasm and nucleus in the medulloblastoma cell lines Daoy and MEB-Med-8A representative of two high risk medulloblastoma entities. We demonstrate that activated Rac1 is subject to substantial downmodulation following administration of the clinically available inhibitor of the PI3K pathway Pictilisib (GDC-0941) and the multityrosine kinase inhibitors Pazopanib and Sorafenib. The application of those drugs was associated with reduced mobility of the medulloblastoma cells and alterations of the actin skeleton. Of note, PI3K inhibition reveals the strongest anti-migratory effect in Daoy cells. Thus, our in vitro observations provide new insights into different strategies of blocking Rac1 and inhibiting migration in medulloblastoma employing clinically available agents paving the way for confirmatory studies in in vivo models.

Amsacrine combined with etoposide and methylprednisolone is a feasible and safe component in first-line intensified treatment of pediatric patients with high-risk acute lymphoblastic leukemia in CoALL08-09 trial.

BACKGROUND: The prognosis of children with acute lymphoblastic leukemia (ALL) has improved considerably over the past five decades. However, to achieve cure in patients with refractory or relapsed disease, novel treatment options are necessary. METHODS: In the multicenter trial Cooperative Study Group for Childhood Acute Lymphoblastic Leukemia (CoALL)08-09, one additional treatment element consisting of the rarely used chemotherapeutic agent amsacrine combined with etoposide and methylprednisolone (AEP) (amsacrine 2 × 100 mg/m2 , etoposide 2 × 500 mg/m2 , and methylprednisolone 4 × 1000 mg/m2 ) was incorporated into the first-line treatment of pediatric patients with poor treatment responses at the end of induction (EOI), measured by minimal residual disease (MRD). These patients were stratified into a high-risk intensified arm (HR-I), including an AEP element at the end of consolidation. Patients with induction failure (IF), that is, with lack of cytomorphological remission EOI, were eligible for hematopoietic stem cell transplantation (HSCT) after remission had been reached. These patients received AEP as a part of their MRD-guided bridging-to-transplant treatments. RESULTS: A significant improvement in probability of overall survival (pOS) was noted for the CoALL08-09 HR-I patients compared to MRD-matched patients from the preceding CoALL07-03 trial in the absence of severe or persistent treatment-related toxicities. Relapse rate and probability of event-free survival (pEFS) did not differ significantly between trials. In patients with IF, stable or improved MRD responses after AEP were observed without severe or persistent treatment-related toxicities. CONCLUSION: In conclusion, AEP is well tolerated as a component of the HR treatment and is useful in bridging-to-transplant settings.

Clofarabine increases the eradication of minimal residual disease of primary B-precursor acute lymphoblastic leukemia compared to high-dose cytarabine without improvement of outcome. Results from the randomized clinical trial 08-09 of the Cooperative Acute Lymphoblastic Leukemia Study Group.

Novel treatment strategies are needed to improve cure for all children with acute lymphoblastic leukemia (ALL). To this end, we investigated the therapeutic potential of clofarabine in primary ALL in trial CoALL 08-09 (clinicaltrials gov. identifier: NCT01228331). The primary study objective was the minimal residual disease (MRD)- based comparative assessment of cytotoxic efficacies of clofarabine 5x40 mg/m2 versus high-dose cytarabine (HIDAC) 4x3g/m2, both in combination with PEG-ASP 2,500 IU/m2 as randomized intervention in early consolidation. The secondary objective was an outcome analysis focused on treatment arm dependence and MRD after randomized intervention. In B-cell precursor (BCP)-ALL, eradication of MRD was more profound after clofarabine compared to cytarabine, with 93 versus 79 of 143 randomized patients per arm reaching MRD-negativity (c2 test P=0.03, leftsided P [Fisher's exact test]=0.04). MRD status of BCP-ALL after randomized intervention maintained its prognostic relevance, with a significant impact on event-free survival (EFS) and relapse rate. However, no difference in outcome regarding EFS and overall survival (OS) between randomized courses was observed (5-year EFS: clofarabine 85.7, SE=4.1 vs. HIDAC 84.8, SE=4.7 [P=0.96]; OS: 95.7, SE=1.9 vs. 92.2, SE=3.2 [P=0.59]), independent of covariates or overall risk strata. Severe toxicities between randomized and subsequent treatment elements were also without significant difference. In conclusion, clofarabine/PEG-ASP is effective and safe, but greater cytotoxic efficacy of clofarabine compared to HIDAC did not translate into improved outcomes indicating a lack of surrogacy of post-intervention MRD at the trial level as opposed to the patient level, which hampers a broader implementation of this regimen in the frontline treatment of ALL.

Targeting EpCAM by a Bispecific Trifunctional Antibody Exerts Profound Cytotoxic Efficacy in Germ Cell Tumor Cell Lines.

Outcome in high-risk patients with refractory or relapsed germ cell tumours (GCT) remains poor. Novel strategies enhancing therapeutic efficacy whilst limiting therapeutic burden are warranted, yet immunotherapy approaches geared towards activating endogenous antitumor responses have not been successful thus far. Redirection of cytotoxic effector cells by bispecific antibodies represents a promising approach in this setting. We demonstrate that the Epithelial Cell Adhesion Molecule (EpCAM) is broadly expressed in GCT cell lines of different histologic origin including seminoma, choriocarcinoma (CHC), and embryonal carcinoma (EC). In these GCT lines of variable EpCAM surface expression, targeting T cells by the prototypic bispecific EpCAM/CD3-antibody (bAb) Catumaxomab together with natural killer (NK) cell engagement via the Fc domain promotes profound cytotoxicity across a broad range of antibody dilutions. In contrast, tumor cell lysis mediated by either immune cell subset alone is influenced by surface density of the target antigen. In the CHC line JAR, NK cell-dependent cytotoxicity dominates, which may be attributed to differential surface expression of immunomodulatory proteins such as MHC-I, CD24, and Fas receptors on CHC and EC. In view of redirecting T cell therapy mediated by bispecific antibodies, such differences in GCT immunophenotype potentially favoring immune escape are worth further investigation.

Health status, health-related quality of life, and socioeconomic outcome in childhood brain tumor survivors: a German cohort study.

BACKGROUND: With rising numbers of childhood cancer survivors, somatic and socioeconomic outcome as well as health-related quality of life (QoL) gain increasing relevance. Based on the first nationwide German Survey on Life Situation, State of Health, and Quality of Life of Childhood Cancer Survivors, the VIVE survey, we report the outcome of survivors of childhood brain tumors localized in the posterior fossa. METHODS: Two hundred seventy participants with a median follow-up period of 21.9 years completed a questionnaire on socioeconomic and somatic late effects as well as a standardized QoL questionnaire (European Organisation for Research and Treatment of Cancer QLQ-C30). Comparisons were performed between World Health Organization (WHO) grades I-II, WHO grades III-IV brain tumor survivors (BTS), and the general population adjusting for potential confounders. RESULTS: The socioeconomic and QoL results of WHO grades I-II BTS were largely comparable to the general population, while grades III-IV BTS were at higher risk for significantly worse outcomes. Of WHO grades III-IV BTS, 36.8% were still living with their parents or in assisted living facilities compared with 16.1% of grades I-II BTS and 7.8% of the age-adjusted general population. Of grades III-IV BTS, 60.8% achieved at least an intermediate school degree in comparison to 80.5% of grades I-II BTS and 75.6% of the general population. Grades III-IV BTS developed up to 2 times more somatic late effects than survivors of grades I-II tumors. CONCLUSION: Derived from a large and homogeneous cohort, these results stress the importance of an appropriate follow-up period focusing not only on physical aspects but encompassing the entire living situation to allow patient-tailored support.

High-Dose Chemotherapy and Blood Autologous Stem-Cell Rescue Compared With Standard Chemotherapy in Localized High-Risk Ewing Sarcoma: Results of Euro-E.W.I.N.G.99 and Ewing-2008.

Purpose For over 30 years, the place of consolidation high-dose chemotherapy in Ewing sarcoma (ES) has been controversial. A randomized study was conducted to determine whether consolidation high-dose chemotherapy improved survival in patients with localized ES at high risk for relapse. Methods Randomization between busulfan and melphalan (BuMel) or standard chemotherapy (vincristine, dactinomycin, and ifosfamide [VAI], seven courses) was offered to patients if they were younger than 50 years of age with poor histologic response (≥ 10% viable cells) after receiving vincristine, ifosfamide, doxorubicin, and etoposide (six courses); or had a tumor volume at diagnosis ≥ 200 mL if unresected, or initially resected, or resected after radiotherapy. A 15% improvement in 3-year event-free survival (EFS) was sought (hazard ratio [HR], 0.60). Results Between 2000 and 2015, 240 patients classified as high risk (median age, 17.1 years) were randomly assigned to VAI (n = 118) or BuMel (n = 122). Seventy-eight percent entered the trial because of poor histologic response after chemotherapy alone. Median follow-up was 7.8 years. In an intent-to-treat analysis, the risk of event was significantly decreased by BuMel compared with VAI: HR, 0.64 (95% CI, 0.43 to 0.95; P = .026); 3- and 8-year EFS were, respectively, 69.0% (95% CI, 60.2% to 76.6%) versus 56.7% (95% CI, 47.6% to 65.4%) and 60.7% (95% CI, 51.1% to 69.6%) versus 47.1% (95% CI, 37.7% to 56.8%). Overall survival (OS) also favored BuMel: HR, 0.63 (95% CI, 0.41 to 0.95; P = .028); 3- and 8-year OS were, respectively, 78.0% (95% CI, 69.6% to 84.5%) versus 72.2% (95% CI, 63.3% to 79.6%) and 64.5% (95% CI, 54.4% to 73.5%) versus 55.6% (95% CI, 45.8% to 65.1%). Results were consistent in the sensitivity analysis. Two patients died as a result of BuMel-related toxicity, one after standard chemotherapy. Significantly more BuMel patients experienced severe acute toxicities from this course of chemotherapy compared with multiple VAI courses. Conclusion BuMel improved EFS and OS when given after vincristine, ifosfamide, doxorubicin, and etoposide induction in localized ES with predefined high-risk factors. For this group of patients, BuMel may be an important addition to the standard of care.

The FDA approved PI3K inhibitor GDC-0941 enhances in vitro the anti-neoplastic efficacy of Axitinib against c-myc-amplified high-risk medulloblastoma.

Aberrant receptor kinase signalling and tumour neovascularization are hallmarks of medulloblastoma development and are both considered valuable therapeutic targets. In addition to VEGFR1/2, expression of PDGFR α/ß in particular has been documented as characteristic of metastatic disease correlating with poor prognosis. Therefore, we have been suggested that the clinically approved multi-kinase angiogenesis inhibitor Axitinib, which specifically targets these kinases, might constitute a promising option for medulloblastoma treatment. Indeed, our results delineate anti-neoplastic activity of Axitinib in medulloblastoma cell lines modelling the most aggressive c-myc-amplified Non-WNT/Non-SHH and SHH-TP53-mutated tumours. Exposure of medulloblastoma cell lines to Axitinib results in marked inhibition of proliferation and profound induction of cell death. The differential efficacy of Axitinib is in line with target expression of medulloblastoma cells identifying VEGFR 1/2, PDGFR α/ß and c-kit as potential markers for drug application. The high specificity of Axitinib and the consequential low impact on the haematopoietic and immune system render this drug ideal multi-modal treatment approaches. In this context, we demonstrate that the clinically available PI3K inhibitor GDC-0941 enhances the anti-neoplastic efficacy of Axitinib against c-myc-amplified medulloblastoma. Our findings provide a rational to further evaluate Axitinib alone and in combination with other therapeutic agents for the treatment of most aggressive medulloblastoma subtypes.

Importance of whole-body imaging with complete coverage of hands and feet in alveolar rhabdomyosarcoma staging.

BACKGROUND: Alveolar rhabdomyosarcoma commonly arises in the extremities and is characterized by aggressive biology and high frequency of metastases. Whole-body imaging is increasingly employed in pediatric oncology but not recommended as standard in the staging of soft-tissue sarcomas. OBJECTIVE: After observing patients with a large symptomatic alveolar rhabdomyosarcoma lesion and a smaller silent lesion in the more distal part of an extremity we sought to estimate the frequency of this constellation. MATERIALS AND METHODS: We retrospectively evaluated the data of prospectively registered paediatric patients (age <21 years) with alveolar rhabdomyosarcoma in the SoTiSaR (Soft Tissue Sarcoma Registry) of the Cooperative Weichteilsarkom Studiengruppe (CWS) 09/2011-04/2015 with regard to whole-body imaging. RESULTS: Seventy-five patients were eligible. Images of 57 patients had been submitted for reference consultation, including 80 whole-body examinations in 36 patients. Among them were 5 patients (14%, 95% confidence interval 3-25%) who had been diagnosed because of a symptomatic lesion while an additional silent lesion in the distal part of an extremity had remained unnoticed and had only been detected by later whole-body imaging. It is noteworthy that in 42 (53%) of all 80 whole-body examinations, the hands and feet had been only partially covered or completely excluded. CONCLUSION: In alveolar rhabdomyosarcoma silent lesions can be overlooked when the distal parts of the limbs are not thoroughly examined and not completely covered by imaging. Missing them influences treatment decisions and prognosis. Our results should be considered when evaluating the potential role of whole-body imaging in rhabdomyosarcoma.

Brentuximab vedotin exerts profound antiproliferative and pro-apoptotic efficacy in CD30-positive as well as cocultured CD30-negative germ cell tumour cell lines.

Prognosis in patients suffering from high-risk, refractory and relapsed germ cell tumours (GCT) often comprising of CD30-positive embryonal carcinoma (EC) components remains poor. Thus, novel treatment strategies are warranted. The antibody-drug conjugate (ADC) brentuximab vedotin delivers the potent antimitotic drug monomethyl auristatin E (MMAE) to CD30-expressing tumour cells. After CD30 binding, internalization and intracellular linker cleavage cytotoxic MMAE can efflux and eradicate neighbouring CD30-negative cells. To analyse cytotoxicity and a potential bystander effect of brentuximab vedotin in GCT, we established an in vitro coculture model mimicking GCT of heterogeneous CD30 positivity and measured cell viability, proliferation and apoptosis after exposure to brentuximab vedotin and unbound MMAE by MTS- and flow cytometry-based CFSE/Hoechst assay. CD30 expression being assessed by quantitative RT-PCR and immunohistochemistry was apparent in all EC cell lines with different intensity. Brentuximab vedotin abrogates cell viability of CD30-positive GCT27 EC line exerting marked time-dependent antiproliferative and pro-apoptotic activity. CD30-negative JAR cultured alone barely responds to brentuximab vedotin, while in coculture with GCT27 brentuximab vedotin induces clear dose-dependent cytotoxicity. Cellular proliferation and cell death are significantly enhanced in CD30-negative JAR cocultured with CD30-positive GCT27 compared to JAR cultured alone in proof of substantial bystander activity of brentuximab vedotin in CD30-negative GCT. We present first evidence that in an in vitro model mimicking GCT of heterogeneous histology, brentuximab vedotin exerts potent antiproliferative and pro-apoptotic activity against both CD30-positive as well as CD30-negative GCT subsets. Our results strongly support translational efforts to evaluate clinical efficacy of brentuximab vedotin in high-risk GCT of heterogeneous CD30 positivity.

Haematological malignancies following temozolomide treatment for paediatric high-grade glioma.

BACKGROUND: Temozolomide (TMZ) is widely used in high-grade glioma (HGG). There is a major concern of treatment-induced secondary haematological malignancies (SHMs). Due to the poor overall survival of HGG patients, the true incidence is yet elusive. Thus, the aim of this study was to determine the risk of SHMs following TMZ in paediatric HGG. METHODS: We analysed 487 patients from the HIT-HGG database of the German-speaking Society of Pediatric Oncology and Hematology with follow up beyond 1 year. RESULTS: The incidence of SHM was 7.7 ± 3.2% at 10 years. No SHM occurred in 194 patients after first-line TMZ therapy, but four out of 131 patients treated with TMZ for relapse following first-line multiagent chemotherapy experienced SHM (20% at 10 years; p = 0.041). SHMs occurred in two out of 162 patients who underwent multiagent chemotherapy without TMZ (4.1% at 10 years). Gender, patient age and acute haematological toxicity during treatment did not affect the incidence of SHMs. CONCLUSION: Data of our cohort do not indicate an increased risk of SHM following TMZ treatment when compared to previous chemotherapy regimen. However, if TMZ is administered as a second-line treatment following conventional chemotherapy regimen, the risk might be disproportionately increasing.

The anti-neoplastic activity of Vandetanib against high-risk medulloblastoma variants is profoundly enhanced by additional PI3K inhibition.

Medulloblastoma is comprised of at least four molecular subgroups with distinct clinical outcome (WHO classification 2016). SHH-TP53-mutated as well as MYC-amplified Non-WNT/Non-SHH medulloblastoma show the worst prognosis.Here we present evidence that single application of the multi-kinase inhibitor Vandetanib displays anti-neoplastic efficacy against cell lines derived from high-risk SHH-TP53-mutated and MYC-amplified Non-WNT/Non-SHH medulloblastoma. The narrow target spectrum of Vandetanib along with a favourable toxicity profile renders this drug ideal for multimodal treatment approaches. In this context our investigation documents that Vandetanib in combination with the clinically available PI3K inhibitor GDC-0941 leads to enhanced cytotoxicity against MYC-amplified and SHH-TP53-mutated medulloblastoma. In line with these findings we show for MYC-amplified medulloblastoma a profound reduction in activity of the oncogenes STAT3 and AKT. Furthermore, we document that Vandetanib and the standard chemotherapeutic Etoposide display additive anti-neoplastic efficacy in the investigated medulloblastoma cell lines that could be further enhanced by PI3K inhibition. Of note, the combination of Vandetanib, GDC-0941 and Etoposide results in MYC-amplified and SHH-TP53-mutated cell lines in complete loss of cell viability. Our findings therefore provide a rational to further evaluate Vandetanib in combination with PI3K inhibitors as well as standard chemotherapeutics in vivo for the treatment of most aggressive medulloblastoma variants.

The PI3K inhibitor GDC-0941 displays promising in vitro and in vivo efficacy for targeted medulloblastoma therapy.

Deregulation of the Phosphoinositide 3-kinase (PI3K)/AKT signalling network is a hallmark of oncogenesis. Also medulloblastoma, the most common malignant brain tumor in children, is characterized by high levels of AKT phosphorylation and activated PI3K signalling in medulloblastoma is associated with enhanced cellular motility, survival and chemoresistency underscoring its role of as a potential therapeutic target. Here we demonstrate that GDC-0941, a highly specific PI3K inhibitor with good clinical tolerability and promising anti-neoplastic activity in adult cancer, also displays anti-proliferative and pro-apoptotic effects in pediatric human medulloblastoma cell lines. Loss in cell viability is accompanied by reduced phosphorylation of AKT, a downstream target of PI3K. Furthermore, we show that GDC-0941 attenuates the migratory capacity of medulloblastoma cells and targets subpopulations expressing the stem cell marker CD133. GDC-0941 also synergizes with the standard medulloblastoma chemotherapeutic etoposide. In an orthotopic xenograft model of the most aggressive human medulloblastoma variant we document that oral adminstration of GDC-0941 impairs tumor growth and significantly prolongs survival. These findings provide a rational to further investigate GDC-0941 alone and in combination with standard chemotherapeutics for medulloblastoma treatment.

In comparative analysis of multi-kinase inhibitors for targeted medulloblastoma therapy pazopanib exhibits promising in vitro and in vivo efficacy.

Regardless of the recent advances in cytotoxic therapies, 30% of children diagnosed with medulloblastoma. succumb to the disease. Therefore, novel therapeutic approaches are warranted. Here we demonstrate that Pazopanib a clinically approved multi-kinase angiogenesis inhibitor (MKI) inhibits proliferation and apoptosis in medulloblastoma cell lines. Moreover, Pazopanib profoundly attenuates medulloblastoma cell migration, a prerequisite for tumor invasion and metastasis. In keeping with the observed anti-neoplastic activity of Pazopanib, we also delineate reduced phosphorylation of the STAT3 protein, a key regulator of medulloblastoma proliferation and cell survival. Finally, we document profound in vivo activity of Pazopanib in an orthotopic mouse model of the most aggressive c-myc amplified human medulloblastoma variant. Pazopanib reduced the growth rate of intracranial growing medulloblastoma and significantly prolonged the survival. Furthermore, to put these results into a broader perspective we analysed Pazopanib side by side with the MKI Sorafenib. Both compounds share a similar target profile but display different pharmacodynamics and pharmacokinetics with distinct cytotoxic activity in different tumor entities. Thus, we identified Pazopanib as a new promising candidate for a rational clinical assessment for targeted paediatric medulloblastoma therapy.

Sustained complete molecular remission after imatinib discontinuation in children with chronic myeloid leukemia.

Approximately 40% of adults with chronic myeloid leukemia (CML) in prolonged complete molecular response (CMR) remain in CMR after imatinib discontinuation. Corresponding information in children is lacking. Two children with CML in CMR for 48 and 19 months after imatinib discontinuation showed low-level fluctuating disease at RNA transcript and genomic DNA levels. Both patients were low risk according to adult criteria. Since adults with molecular relapse responded to re-introduction of imatinib, we postulated that treatment discontinuation in low risk children might be justified within clinical trials with close monitoring. This may help to minimize exposure to imatinib and its potential side effects.

Downregulation of 14q32 microRNAs in Primary Human Desmoplastic Medulloblastoma.

Medulloblastoma (MB) is one of the most common pediatric cancers, likely originating from abnormal development of cerebellar progenitor neurons. MicroRNA (miRNA) has been shown to play an important role in the development of the central nervous system. Microarray analysis was used to investigate miRNA expression in desmoplastic MB from patients diagnosed at a young age (1 or 2 years old). Normal fetal or newborn cerebellum was used as control. A total of 84 differentially expressed miRNAs (64 downregulated and 20 upregulated) were found. Most downregulated miRNAs (32/64) were found to belong to the cluster of miRNAs at the 14q32 locus, suggesting that this miRNA locus is regulated as a module in MB. Possible mechanisms of 14q32 miRNAs downregulation were investigated by the analysis of publicly available gene expression data sets. First, expression of estrogen-related receptor-γ (ESRRG), a reported positive transcriptional regulator of some 14q32 miRNAs, was found downregulated in desmoplastic MB. Second, expression of the parentally imprinted gene MEG3 was lower in MB in comparison to normal cerebellum, suggesting a possible epigenetic silencing of the 14q32 locus. miR-129-5p (11p11.2/7q32.1), miR-206 (6p12.2), and miR-323-3p (14q32.2), were chosen for functional studies in DAOY cells. Overexpression of miR-129-5p using mimics decreased DAOY proliferation. No effect was found with miR-206 or miR-323 mimics.