Ziad Khatib

Preponderance of Thiopurine S-Methyltransferase Deficiency and Heterozygosity Among Patients Intolerant to Mercaptopurine or Azathioprine

PURPOSE To assess thiopurine S-methyltransferase (TPMT) phenotype and genotype in patients who were intolerant to treatment with mercaptopurine (MP) or azathioprine (AZA), and to evaluate their clinical management. PATIENTS AND METHODS TPMT phenotype and thiopurine metabolism were assessed in all patients referred between 1994 and 1999 for evaluation of excessive toxicity while receiving MP or AZA. TPMT activity was measured by radiochemical analysis, TPMT genotype was determined by mutation-specific polymerase chain reaction restriction fragment length polymorphism analyses for the TPMT*2, *3A, *3B, and *3C alleles, and thiopurine metabolites were measured by high-performance liquid chromatography. RESULTS Of 23 patients evaluated, six had TPMT deficiency (activity < 5 U/mL of packed RBCs [pRBCs]; homozygous mutant), nine had intermediate TPMT activity (5 to 13 U/mL of pRBCs; heterozygotes), and eight had high TPMT activity (> 13.5 U/mL of pRBCs; homozygous wildtype). The 65.2% frequency of TPMT-deficient and heterozygous individuals among these toxic patients is significantly greater than the expected 10% frequency in the general population (P <.001, chi(2)). TPMT phenotype and genotype were concordant in all TPMT-deficient and all homozygous-wildtype patients, whereas five patients with heterozygous phenotypes did not have a TPMT mutation detected. Before thiopurine dosage adjustments, TPMT-deficient patients experienced more frequent hospitalization, more platelet transfusions, and more missed doses of chemotherapy. Hematologic toxicity occurred in more than 90% of patients, whereas hepatotoxicity occurred in six patients (26%). Both patients who presented with only hepatic toxicity had a homozygous-wildtype TPMT phenotype. After adjustment of thiopurine dosages, the TPMT-deficient and heterozygous patients tolerated therapy without acute toxicity. CONCLUSION There is a significant (> six-fold) overrepresentation of TPMT deficiency or heterozygosity among patients developing dose-limiting hematopoietic toxicity from therapy containing thiopurines. However, with appropriate dosage adjustments, TPMT-deficient and heterozygous patients can be treated with thiopurines, without acute dose-limiting toxicity.

A phase II trial of a multi-agent oral antiangiogenic (metronomic) regimen in children with recurrent or progressive cancer

Preclinical models show that an antiangiogenic regimen at low‐dose daily (metronomic) dosing may be effective against chemotherapy‐resistant tumors. We undertook a prospective, open‐label, single‐arm, multi‐institutional phase II study to evaluate the efficacy of a “5‐drug” oral regimen in children with recurrent or progressive cancer.

Tamoxifen Modulation of Etoposide Cytotoxicity Involves Inhibition of Protein Kinase C Activity and Insulin-Like Growth Factor II Expression in Brain Tumor Cells

Tamoxifen, a non-steroidal anti-estrogen widely used against breast cancer, is also useful for treatment of other malignancies, due to its sensitizing effect on other chemotherapeutic agents and radiation. We have investigated the advantages of combining tamoxifen with one of the commonly used cancer chemotherapeutic drug, etoposide (VP-16) in brain tumor cell lines. While tamoxifen (10 uM) increased etoposide cytotoxicity 8.3-fold in the human glioma cell line (HTB-14), it increased etoposide cytotoxicity 47.5- and 40-fold in two primary cell lines established from pediatric medulloblastoma patients (MCH-BT-31 and MCH-BT-39), respectively. Similarly, in the pediatric ependymoma cell lines (MCH-BT-30 and MCH-BT-52), tamoxifen enhanced etoposide cytotoxicity 6- and 2.68-fold, respectively. CalcuSyn analysis of cytotoxicity data showed that tamoxifen and etoposide combinations were synergistic with combination index values ranging from 0.243 to 0.369 at IC50 level among different pediatric brain tumor cell lines. Tamoxifen is also cytotoxic at higher concentrations (>20 μM) in brain tumor cells. To understand the mechanism underlying the tamoxifen modulation of etoposide cytotoxicity, we analyzed expression of P-glycoprotein (P-gp), insulin-like growth factor-I receptor (IGF-IR), IGF-I, IGF-II and estrogen receptor as well as protein kinase C (PKC) activity. While P-gp, IGF-IR and IGF-I were not affected, enhanced inhibition of PKC, and IGF-II were observed in brain tumor cells treated with tamoxifen and etoposide combination as compared to cells treated with either drug alone. Tamoxifen at 10 μM when combined with etoposide at 0–100 μM concentrations reduced PKC activity 77% compared to only 58% without tamoxifen. IGF-II expression decreased to 48.6% of the untreated control in the combination treatment as compared to 31.2% for etoposide alone and 26.2% for tamoxifen alone treatments. These results suggest that inhibitory effect of tamoxifen on brain tumor cells manifest through different mechanisms involving inhibition of targets such as PKC and IGF-II.

Molecular studies in pediatric medulloblastomas.

Ten pediatric medulloblastoma patients were analyzed for DNA content, cell cycle, expression of drug resistance, apoptosis, cell proliferation, andN-myc genes to determine their prognostic significance. Medulloblastoma patients with progressive disease had fourth ventricle foraminal extension and larger tumors in the imaging studies. Patients with aneuploid tumors responded well to treatment regimens as compared with those with diploid tumors. Cell cycle analysis showed that the patients with progressive disease had a high S-phase fraction in the tumor cell population as compared with patients with favorable response to treatment. The correlation coefficients betweenBcl-2 andMRP, Bcl-2 andBax, p53 andp21, as well asKi67 andPCNA were positive and significant, indicating their possible coregulated expression. The relationship between these markers indicates their relative and cumulative effect on cellular drug resistance, apoptosis, and/or cell proliferation in pediatric medulloblastomas.

Nonoperative management of solitary eosinophilic granulomas of the calvaria

OBJECT Solitary eosinophilic granuloma (EG) of the calvaria is most commonly treated with surgical excision. The authors hypothesize that many solitary EGs will resolve without intervention, and observation may be a reasonable option. This study was undertaken to investigate that hypothesis. METHODS The authors reviewed their institutional records and identified 14 cases of solitary calvarial EG. In 6 cases the patients underwent resection based on family and/or neurosurgeon preferences. A strategy of nonoperative management (purposeful observation) was chosen for the other 8 cases. The authors report the clinical course and imaging results in these 8 cases. RESULTS One of the 8 patients underwent surgery 2 months after presentation because of slight enlargement of the lesion and increasing pain. After a median follow-up period of 1 year (range 6-19 months), none of the other patients had required surgery. Five of these 7 patients had pain at presentation. Pain resolved completely in all 5. The remaining 2 remained asymptomatic. Complete resolution of pain was reported in the 5 patients who had pain at presentation. There was complete clinical resolution of the palpable soft-tissue lesion in all 7 cases. Complete radiographic resolution of the lesion was observed in 5 cases and near-complete resolution in the remaining 2. CONCLUSIONS Observation is a safe and reasonable approach in the management of solitary calvarial EG and may prevent unnecessary surgical interventions.

Acute lymphocytic leukemia in a child with Beckwith-Wiedemann syndrome.

Beckwith-Wiedemann syndrome (BWS) is an overgrowth syndrome characterized by neonatal hypoglycemia, abdominal wall defects, macroglossia, organomegaly, ear pits and creases, hemihypertrophy, and increased birthweight. Children with BWS have an increased risk of malignancy. The authors present the case of a 3-year-old boy diagnosed with both BWS and acute lymphocytic leukemia (ALL). This case report will elaborate on the possibilities as to how BWS and ALL may be associated due to abnormal genomic imprinting and IGF dysregulation.

Rosai–Dorfman disease following bone marrow transplantation for pre‐B cell acute lymphoblastic leukemia

A child with acute pre‐B cell lymphoblastic leukemia underwent haploidentical bone marrow transplantation (BMT) after first relapse. Approximately 8 months after the BMT, he developed a soft tissue mass overlying a defect in the left frontal bone. He was found to have several additional osteolytic lesions but no evidence of lymphadenopathy or organomegaly. A biopsy of the presenting lesion demonstrated a polymorphous infiltrate composed predominantly of S‐100 protein and CD68 immunoreactive histiocytic cells. Together with the presence of emperipolesis, the process was interpreted as Rosai–Dorfman (R–D) disease. He received chemotherapy with vinblastine, prednisone, 6‐mercaptopurine and methotrexate and has been in remission for over 4 years. Only one previous example of acute lymphoblastic leukemia in childhood has been reported with R–D disease. Pediatr Blood Cancer 2008;51:433–435.

Bilateral conjunctival extranodal marginal zone B‐cell lymphoma

Extranodal marginal zone B‐cell lymphomas (EMZLs), while relatively common in adults, are rare entities in the pediatric population. A subclass of the typically aggressive non‐Hodgkin lymphomas, the few reported pediatric cases indicate that, as in adults, these tumors tend to be indolent. We present a case of EMZL arising in the conjunctivae in a 9‐year‐old male with bilateral disease. The patient was treated with surgical excision alone and has remained disease‐free 6 years after the operation. Pediatr Blood Cancer. 2010;55:1414–1416.

The genetic landscape of ganglioglioma

Ganglioglioma is the most common epilepsy-associated neoplasm that accounts for approximately 2% of all primary brain tumors. While a subset of gangliogliomas are known to harbor the activating p.V600E mutation in the BRAF oncogene, the genetic alterations responsible for the remainder are largely unknown, as is the spectrum of any additional cooperating gene mutations or copy number alterations. We performed targeted next-generation sequencing that provides comprehensive assessment of mutations, gene fusions, and copy number alterations on a cohort of 40 gangliogliomas. Thirty-six harbored mutations predicted to activate the MAP kinase signaling pathway, including 18 with BRAF p.V600E mutation, 5 with variant BRAF mutation (including 4 cases with novel in-frame insertions at p.R506 in the β3-αC loop of the kinase domain), 4 with BRAF fusion, 2 with KRAS mutation, 1 with RAF1 fusion, 1 with biallelic NF1 mutation, and 5 with FGFR1/2 alterations. Three gangliogliomas with BRAF p.V600E mutation had concurrent CDKN2A homozygous deletion and one additionally harbored a subclonal mutation in PTEN. Otherwise, no additional pathogenic mutations, fusions, amplifications, or deletions were identified in any of the other tumors. Amongst the 4 gangliogliomas without canonical MAP kinase pathway alterations identified, one epilepsy-associated tumor in the temporal lobe of a young child was found to harbor a novel ABL2-GAB2 gene fusion. The underlying genetic alterations did not show significant association with patient age or disease progression/recurrence in this cohort. Together, this study highlights that ganglioglioma is characterized by genetic alterations that activate the MAP kinase pathway, with only a small subset of cases that harbor additional pathogenic alterations such as CDKN2A deletion.

Inhibition of AKT signaling by supercritical CO2 extract of mango ginger (Curcuma amada Roxb.) in human glioblastoma cells

Abstract Background: Mango ginger (Curcuma amada Roxb.) is a less-investigated herb for anticancer properties than other related Curcuma species. AKT (a serine/threonine protein kinase B, originally identified as an oncogene in the transforming retrovirus AKT8) plays a central role in the development and promotion of cancer. In this investigation, we have analyzed the effect of supercritical CO2 extract of mango ginger (CA) on the genetic pathways associated with AKT signaling in human glioblastoma cells. Methods: The inhibitory effect of supercritical CO2 extract of mango ginger (Curcuma amada) on AKT signaling was investigated in U-87MG glioblastoma cells. Results: CA was highly cytotoxic to glioblastoma cell line (IC50=4.92±0.81 µg/mL) compared to mHypoE-N1 normal mouse hypothalamus cell line (IC50=40.57±0.06 µg/mL). CA inhibits AKT (protein Kinase B) and adenosine monophophate -activated protein kinase α (AMPKα) phosphorylation significantly in a dose-dependent manner. The cell migration which is necessary for invasion and metastasis was also inhibited by CA treatment, with about 43% reduction at 20 µg/mL concentration. Analysis of mRNA and protein expression of genes associated with apoptosis, cell proliferation and angiogenesis showed that CA modulates expression of genes associated with apoptosis (Bax, Bcl-2, Bcl-X, BNIP3, caspase-3, mutant p53 and p21), cell proliferation (Ki67) and angiogenesis vascular endothelial growth factor (VEGF). Additionally, heat shock protein 90 (HSP90) and AMPKα genes interacting with the AKT signaling pathway were also downregulated by CA treatment. Conclusions: These results indicate the molecular targets and mechanisms underlying the anticancer effect of CA in human glioblastoma cells.