Roberta Migliorati

The micro-RNA 199b-5p regulatory circuit involves Hes1, CD15, and epigenetic modifications in medulloblastoma

Micro-RNA (miR) 199b-5p targets Hes1 in medulloblastoma, one of the downstream effectors of both the canonical Notch and noncanonical Sonic Hedgehog pathways. In medulloblastoma patients, expression of miR-199b-5p is significantly decreased in metastatic cases, thus suggesting a downregulation mechanism. We studied this mechanism, which is mediated mostly by Hes1 and epigenetic promoter modifications. The miR-199b-5p promoter region was characterized, which identified a Hes1 binding site, thus demonstrating a negative feedback loop of regulation. MiR-199b-5p was shown to be downregulated in several medulloblastoma cell lines and in tumors by epigenetic methylation of a cytosine-phosphate-guanine island upstream of the miR-199b-5p promoter. Furthermore, the cluster of differention (CD) carbohydrate antigen CD15, a marker of medulloblastoma tumor-propagating cells, is an additional direct target of miR-199b-5p. Most importantly, regulation of miR-199b-5p expression in these CD15+/CD133+ tumor-propagating cells was influenced by only Hes1 expression and not by any epigenetic mechanism of regulation. Moreover, reverse-phase protein array analysis showed both the Akt and extracellular-signal-regulated kinase pathways as being mainly negatively regulated by miR-199b-5p expression in several medulloblastoma cell lines and in primary cell cultures. We present here the finely tuned regulation of miR-199b-5p in medulloblastoma, underlining its crucial role by its additional targeting of CD15.

Phase I study of temozolomide combined with oral etoposide in children with recurrent or progressive medulloblastoma

BACKGROUND The prognosis of recurrent or progressive medulloblastoma (MB) is still poor. This study was designed to investigate the potential therapeutic benefit of combination therapy with temozolomide (TMZ) and oral etoposide (VP-16) in children with progressive or relapsed MB. Given the oral administration of both drugs the regimen was administered outpatient. METHODS A phase I trial was conducted to establish the maximum tolerated dose (MTD) of TMZ and oral VP-16. This orally administered combination was investigated by classical 3+3 design. Cohorts of patients were enrolled at four different levels: (1) TMZ 120 mg/m(2) on days 1-5 and VP-16 50 mg/m(2) on days 1-8; (2) TMZ 150 mg/m(2) on days 1-5 and VP-16 50 mg/m(2) on days 1-8; (3) TMZ 150 mg/m(2) on days 1-5 and VP-16 50 mg/m(2) on days 1-10; (4) TMZ 150 mg/m(2) on days 1-5 and VP-16 50 mg/m(2) on days 1-12. Therapy was administered in 28-d courses. A total of 66 courses were administered to 14 patients with a median age of 5.7 years. RESULTS None of the 3 patients at dose levels 1 and 2 had dose-limiting toxicity (DLT). Of the 6 patients at dose level 3, 1 patient had DLT. At dose level 4, grade 4 thrombocytopaenia and neutropaenia were observed in the first 2 patients enrolled. Therefore, the MTD was established at dose level 3. CONCLUSION The recommended phase II dose in children is TMZ 150 mg/m(2) on days 1-5 and VP-16 50 mg/m(2) on days 1-10 every 28 d. The combination was well tolerated and demonstrated antitumour activity.

Shunt Related Abdominal Metastases in an Infant with Medulloblastoma: Long Term Remission by Systemic Chemotherapy and Surgery

This is the first reported case of long remission of abdominal metastases spread through a ventriculo-peritoneal shunt in an infant diagnosed, four years ago, at age 1 year and 10 months, to have cerebral medulloblastoma. Two years later, while in second complete remission of his cerebral tumor, he showed abdominal metastases, successfully treated by platinum based chemotherapy and surgery. One year later, a second abdominal relapse and hepatic metastases were treated by doxorubicin administration and surgery. Since then the child remained in continuous complete remission. This unusual favorable outcome can be explained by an extreme responsiveness of the tumor, unprotected by the blood brain barrier, to systemic chemotherapy, particularly to doxorubicin administration. The need for careful surveillance of patients with ventriculo-peritoneal shunts is emphasized. Searching for new tools, such as entrapment of doxorubicin in liposomes, able to overcome the blood–brain barrier and to expose brain tumors to effective drugs, probably represents the best choice for future treatment strategies of CNSbreak tumors.

Second-line chemotherapy with the association of liposomal daunorubicin, carboplatin and etoposide in children with recurrent malignant brain tumors.

Progressive or recurrent high-grade gliomas are characterized by a very poor prognosis, and the relevance of second-line chemotherapy is still unassessed.Although it has been reported that liposomal anthracyclines and carboplatin show some activity in these patients, their association has never been investigated.We have treated six children with recurrent high-grade glioma after surgery, radiotherapy and chemotherapy, and one child with progressive teratoid/rhabdoid tumor with the combination of liposomal daunorubicin and carboplatin plus etoposide. Five out of seven children showed a major response and the 29 month progression-free survival was 38%. The above regimen was feasible and children showed only little and transient hematological toxicity.In our opinion, these results justify further investigation of the above combination chemotherapy for recurrent or progressive malignant brain tumors in children.

Salivary gland carcinomas in children and adolescents: The Italian TREP project experience

Salivary gland carcinomas are extremely rare in pediatric age. We report the clinical features of a series of children/adolescents with salivary gland carcinomas prospectively registered in the Italian TREP (Rare Tumors in Pediatric Age) project.

Efficacy of Sequential Chemotherapy Including Methotrexate and Doxorubicin in an Infant with Partially Resected Choroid Plexus Carcinoma

This report refers to a 3-month-old male, with a residual choroid plexus carcinoma following partial resection, who was successfully treated with sequential chemotherapy without any postoperative radiation therapy. Along with carboplatin, we also used doxorubicin and methotrexate, hypothesizing that, given the patient’s age, the blood-brain barrier should not hamper drug delivery to the tumor. According to this hypothesis, the treatment achieved complete remission of the disease, which lasts 27 months after the diagnosis. This result deserves further studies to assess the possible curative role of chemotherapy in very young patients suffering from choroid plexus carcinoma.

Constitutional 11q14-q22 chromosome deletion syndrome in a child with neuroblastoma MYCN single copy.

Constitutional 11q deletion is a chromosome imbalance possibly found in MCA/MR patients analyzed for chromosomal anomalies. Its role in determining the phenotype depends on extension and position of deleted region. Loss of heterozygosity of 11q (region 11q23) is also associated with neuroblastoma, the most frequent extra cranial cancer in children. It represents one of the most frequent cytogenetic abnormalities observed in the tumor of patients with high-risk disease even if germline deletion of 11q in neuroblastoma is rare. Hereby, we describe a 18 months old girl presenting with trigonocephaly and dysmorphic facial features, including hypotelorism, broad depressed nasal bridge, micrognathia, synophrys, epicanthal folds, and with a stage 4 neuroblastoma without MYCN amplification, carrying a germline 11q deletion (11q14.1-q22.3), outside from Jacobsen syndrome and from neuroblastoma 11q critical regions. The role of 11q deletion in determining the clinical phenotype and its association with neuroblastoma development in the patient are discussed.

Treatment of Medulloblastoma: Chemotherapy

Medulloblastoma (MB) is one of the most common malignant brain tumors in childhood. Its origin is from the cerebellar vermis or from one of cerebellar hemispheres. Its extracerebellar counterparts are the primitive neuroectodermal tumors known as PNETs. Among pediatric embryonal central nervous system tumors, MB generally shows a better prognosis with 5-year survival rates of up to 70 % in standard-risk patients. The standard risk identifies patients fulfilling following criteria: total or subtotal resection, age over 3 years, and localized disease without dissemination. Chemotherapy modified the prognosis of MB since 1976 when the first trial of the International Society of Paediatric Oncology (SIOP I) introduced adjuvant chemotherapy (vincristine, lomustine, and prednisone). Now, we consider MB a chemoresponsive tumor and chemotherapy plays a role together with surgery and radiotherapy. Resistance to treatments is on study: biological differences may explain different behavior of neoplastic cells and different fates between patients inside the same risk group. Ongoing research will point to the knowledge of deregulation of embryogenetic signalling pathways involved in the pathogenesis of MB and in self-maintenance of tumoral stem cells. Future therapeutic trials will have different stratification of patients based on biological markers.