John P. Perentesis

Renal carcinomas with the t(6;11)(p21;q12): Clinicopathologic features and demonstration of the specific alpha-TFEB gene fusion by immunohistochemistry, RT-PCR, and DNA PCR

A highly distinctive subset of renal neoplasms of children and young adults contains a t(6;11)(p21;q12), a translocation recently been shown to result in fusion of Alpha, a gene on 11q12, with the transcription factor gene TFEB on 6p21. To define the clinicopathologic spectrum of this nascent entity and to establish immunohistochemical (IHC) and molecular methods for the detection of the specific Alpha-TFEB fusion, we studied 7 renal neoplasms that showed the t(6;11) by cytogenetic or molecular analysis (patient age: range, 9-33 years; mean, 17 years). While all tumors were confined to the kidney, 3 tumors demonstrated vascular invasion. In limited follow-up, none has metastasized. We postulated that the Alpha-TFEB gene fusion may result in deregulated expression of TFEB protein that would be detectable by IHC. Using a polyclonal antibody to TFEB on formalin-fixed, paraffin-embedded tissue sections, we found that all 7 renal neoplasms with the t(6;11) demonstrated moderate (2 cases) or strong (5 cases) nuclear TFEB immunoreactivity. In contrast, none of 1089 other tumors (of 74 histologic types from 16 sites) labeled significantly for TFEB. Nuclear immunoreactivity for TFEB in normal tissues was extremely rare, limited to weak labeling of scattered benign lymphocytes. We also show that the Alpha-TFEB fusion RNAs are highly variable in size and structure, making detection by reverse-transcriptase polymerase chain reaction (RT-PCR) less reliable than for other gene fusions. Because Alpha is an intronless gene and therefore lacks splice signals, we hypothesized that DNA PCR and RT-PCR products would be identical, allowing for the use of more robust molecular assays based on genomic DNA. Indeed, in 2 cases with available frozen tissue, we showed the genomic Alpha-TFEB junction detected by DNA PCR to be identical to the Alpha-TFEB fusion mRNA detected by RT-PCR. In summary, renal neoplasms with the t(6;11) are a distinctive neoplastic entity with many similarities to the Xp11 translocation carcinomas, and together with the latter form a growing “MiTF/TFE family” of translocation carcinomas. Nuclear immunoreactivity for TFEB protein is a highly sensitive and specific diagnostic marker for these renal neoplasms. Finally, the special molecular features of the Alpha-TFEB gene fusion allow its molecular detection by DNA PCR as a robust alternative to RT-PCR in clinical tumor samples.

Glutathione S-Transferase Polymorphisms and Outcome of Chemotherapy in Childhood Acute Myeloid Leukemia

PURPOSE Glutathione S-transferase theta (GSTT1) and mu (GSTM1) genes are polymorphic, the genes being absent in approximately 15% and 50% of the population, respectively. Because glutathione S-transferases may be involved in the metabolism of chemotherapy drugs, we hypothesized that presence or absence of the genes may influence the outcome of treatment for childhood acute myeloid leukemia (AML). PATIENTS AND METHODS We genotyped GSTT1 and GSTM1 in 306 children with AML receiving chemotherapy on Childrens Cancer Group therapeutic studies. Outcomes were compared in those with and without GSTT1 and GSTM1 genes. RESULTS Patients with the GSTT1-negative genotype had reduced survival compared with those with at least one GSTT1 allele (GSTT1 positive) (52% v 40% at 5 years; log-rank P =.05). A multivariate model of survival adjusted for age group, sex, WBC count, chloroma, CNS involvement, and French-American-British group confirmed the increased risk of death in the GSTT1-null cases (relative risk, AQ 1.6; P =.02). The frequency of death in remission was increased in GSTT1-negative cases compared with GSTT1-positive cases (24% v 12%, log-rank P =.05). The frequency of relapse from end of induction was similar in GSTT1-negative and GSTT1-positive cases (38% v 35%, log-rank P =.5). CONCLUSION Children who lacked GSTT1 had greater toxicity and reduced survival after chemotherapy for AML compared with children with at least one GSTT1 allele. If confirmed in further studies, GSTT1 genotype might be useful in selecting appropriate chemotherapy regimens for children with AML.

Management of Metabolic Effects Associated With Anticancer Agents Targeting the PI3K-Akt-mTOR Pathway

Agents inhibiting the phosphoinositide 3-kinase-Akt-mammalian target of rapamycin (PAM) pathway are currently in various stages of clinical development in oncology, ranging from some in early-phase evaluations to others that have already received regulatory approval for treatment in advanced cancers. The administration of PAM pathway inhibitors has been associated with metabolic toxicities of hyperlipidemia and hyperglycemia. The PAM Task Force of the National Cancer Institute Investigational Drug Steering Committee convened an interdisciplinary expert panel to review the pathophysiology of hyperlipidemia and hyperglycemia induced by PAM pathway inhibitors, summarize the incidence of these metabolic toxicities induced by such agents in the current literature, advise on clinical trial screening and monitoring criteria, and provide management guidance and therapeutic goals on occurrence of these toxicities. The overarching aim of this consensus report is to raise awareness of these metabolic adverse events to enable their early recognition, regular monitoring, and timely intervention in clinical trials. Hyperglycemia and hyperlipidemia are generally not acutely toxic and most often reversible with therapeutic intervention. Dose modifications or discontinuation of PAM pathway inhibitors should only be considered in situations of severe events or if progressive metabolic derangement persists after therapeutic interventions have been attempted for a sufficient duration. Specialty consultation should be sought to aid clinical trial planning and the management of these metabolic adverse events.

Natural history of transient myeloproliferative disorder clinically diagnosed in Down syndrome neonates: a report from the Children's Oncology Group Study A2971

Transient myeloproliferative disorder (TMD), restricted to newborns with trisomy 21, is a megakaryocytic leukemia that although lethal in some is distinguished by its spontaneous resolution. Later development of acute myeloid leukemia (AML) occurs in some. Prospective enrollment (n = 135) elucidated the natural history in Down syndrome (DS) patients diagnosed with TMD via the use of uniform monitoring and intervention guidelines. Prevalent at diagnosis were leukocytosis, peripheral blast exceeding marrow blast percentage, and hepatomegaly. Among those with life-threatening symptoms, most (n = 29/38; 76%) received intervention therapy until symptoms abated and then were monitored similarly. Organomegaly with cardiopulmonary compromise most frequently led to intervention (43%). Death occurred in 21% but only 10% were attributable to TMD (intervention vs observation patients: 13/14 vs 1/15 because of TMD). Among those solely observed, peripheral blasts and all other TMD symptoms cleared at a median of 36 and 49 days from diagnosis, respectively. On the basis of the diagnostic clinical findings of hepatomegaly with or without life-threatening symptoms, 3 groups were identified with differing survival: low risk with neither finding (38%), intermediate risk with hepatomegaly alone (40%), and high risk with both (21%; overall survival: 92% ± 8%, 77% ± 12%, and 51% ± 19%, respectively; P ≤ .001). Among all, AML subsequently occurred in 16% at a median of 441 days (range, 118-1085 days). The trial is registered at http://www.clinicaltrials.gov as NCT00003593.

Effective in vivo targeting of the mammalian target of rapamycin pathway in malignant peripheral nerve sheath tumors

Malignant peripheral nerve sheath tumors (MPNST) are chemoresistant sarcomas with poor 5-year survival that arise in patients with neurofibromatosis type 1 (NF1) or sporadically. We tested three drugs for single and combinatorial effects on collected MPNST cell lines and in MPNST xenografts. The mammalian target of rapamycin complex 1 inhibitor RAD001 (Everolimus) decreased growth 19% to 60% after 4 days of treatment in NF1 and sporadic-derived MPNST cell lines. Treatment of subcutaneous sporadic MPNST cell xenografts with RAD001 significantly, but transiently, delayed tumor growth, and decreased vessel permeability within xenografts. RAD001 combined with the epidermal growth factor receptor tyrosine kinase inhibitor erlotinib caused additional inhibitory effects on growth and apoptosis in vitro, and a small but significant additional inhibitory effect on MPNST growth in vivo that were larger than the effects of RAD001 with doxorubicin. RAD001 plus erlotinib, in vitro and in vivo, reduced phosphorylation of AKT and total AKT levels, possibly accounting for their additive effect. The results support the consideration of RAD001 therapy in NF1 patient and sporadic MPNST. The preclinical tests described allow rapid screening strata for drugs that block MPNST growth, prior to tests in more complex models, and should be useful to identify drugs that synergize with RAD001. [Mol Cancer Ther 2008;7(5):1237–45]

RAS oncogene mutations and outcome of therapy for childhood acute lymphoblastic leukemia

Activating mutations in the RAS oncogenes are among the most common genetic alterations in human cancers, including patients with acute lymphoblastic leukemia (ALL). We sought to define the frequency and spectrum, and possible prognostic importance, of N- and K-RAS mutations in children with ALL treated with contemporary therapy. Leukemic blast DNA from 870 children was analyzed for the presence of activating mutations in the N- or K-RAS oncogenes using a sensitive mutation detection algorithm. RAS mutations were present in the blasts of 131 (15.1%) pediatric ALL patients. The spectrum of mutations included 81 (9.3%) mutations of codons 12/13 of N-RAS, 12 (1.4%) mutations of codon 61 of N-RAS, 39 (4.5%) mutations of codons 12/13 of K-RAS, and 2 (0.2%) mutations of codon 61 of K-RAS. The presence of N- or K-RAS mutations was not associated with white blood cell count at diagnosis, sex, race, extramedullary testicular involvement, central nervous system disease, or NCI/CTEP ALL Risk Group. Patients with an exon 1 K-RAS mutation (codons 12/13) were significantly younger at diagnosis (P=0.001) and less frequently B-lineage phenotype (P=0.01). RAS mutation status did not predict overall survival, event-free survival and disease-free survival. While N- and K-RAS mutations can be identified in 15% of children with newly diagnosed ALL, they do not represent a significant risk factor for outcome using contemporary chemotherapy regimens.

Vav3 collaborates with p190-BCR-ABL in lymphoid progenitor leukemogenesis, proliferation, and survival.

Despite the introduction of tyrosine kinase inhibitor therapy, the prognosis for p190-BCR-ABL(+) acute lymphoblastic leukemia remains poor. In the present study, we present the cellular and molecular roles of the Rho GTPase guanine nucleotide exchange factor Vav in lymphoid leukemogenesis and explore the roles of Vav proteins in BCR-ABL-dependent signaling. We show that genetic deficiency of the guanine nucleotide exchange factor Vav3 delays leukemogenesis by p190-BCR-ABL and phenocopies the effect of Rac2 deficiency, a downstream effector of Vav3. Compensatory up-regulation of expression and activation of Vav3 in Vav1/Vav2-deficient B-cell progenitors increases the transformation ability of p190-BCR-ABL. Vav3 deficiency induces apoptosis of murine and human leukemic lymphoid progenitors, decreases the activation of Rho GTPase family members and p21-activated kinase, and is associated with increased Bad phosphorylation and up-regulation of Bax, Bak, and Bik. Finally, Vav3 activation only partly depends on ABL TK activity, and Vav3 deficiency collaborates with tyrosine kinase inhibitors to inhibit CrkL activation and impair leukemogenesis in vitro and in vivo. We conclude that Vav3 represents a novel specific molecular leukemic effector for multitarget therapy in p190-BCR-ABL-expressing acute lymphoblastic leukemia.

XRCC1 and Glutathione-S-Transferase Gene Polymorphisms and Susceptibility to Radiotherapy- Related Malignancies in Survivors of Hodgkin Disease A Report from the Childhood Cancer Survivor Study

One of the most serious late effects of treatment for childhood cancer is the occurrence of subsequent malignancy. Survivors of Hodgkin disease (HD), in particular, have been shown to be at high risk of subsequent malignancy, the occurrence of which has been associated strongly with exposure to radiotherapy.

Differences in outcomes of newly diagnosed acute myeloid leukemia for adolescent/young adult and younger patients: a report from the Children's Oncology Group.

Studies comparing survival of adolescent and young adult (AYA) patients to that of younger patients with newly diagnosed acute myeloid leukemia (AML) have yielded conflicting results. In order to more accurately characterize relative survival and other outcomes of AYA patients, a cross‐study analysis was conducted using data from recent trials conducted by the Childrens Cancer Group (CCG) and Childrens Oncology Group (COG).

Phase I trial of two schedules of vincristine, oral irinotecan, and temozolomide (VOIT) for children with relapsed or refractory solid tumors: a Children's Oncology Group phase I consortium study.

In preclinical models, temozolomide, and vincristine are additive or synergistic with irinotecan. We examined this three‐drug combination in children with relapsed solid tumors. Patients received orally administered irinotecan together with temozolomide and vincristine on two different schedules, using cefixime to reduce irinotecan‐associated diarrhea.