HDAC1 and HDAC6 are essential for driving growth in IDH1 mutant glioma

Low-grade and secondary high-grade gliomas frequently contain mutations in the IDH1 or IDH2 metabolic enzymes that are hypothesized to drive tumorigenesis by inhibiting many of the chromatin-regulating enzymes that regulate DNA structure. Histone deacetylase inhibitors are promising anti-cancer agents and have already been used in clinical trials. However, a clear understanding of their mechanism or gene targets is lacking. In this study, the authors genetically dissect patient-derived IDH1 mutant cultures to determine which HDAC enzymes drive growth in IDH1 mutant gliomas. A panel of patient-derived gliomasphere cell lines (2 IDH1 mutant lines, 3 IDH1 wildtype lines) were subjected to a drug-screen of epigenetic modifying drugs from different epigenetic classes. The effect of LBH (panobinostat) on gene expression and chromatin structure was tested on patient-derived IDH1 mutant lines. The role of each of the highly expressed HDAC enzymes was molecularly dissected using lentiviral RNA interference knock-down vectors and a patient-derived IDH1 mutant in vitro model of glioblastoma (HK252). These results were then confirmed in an in vivo xenotransplant model (BT-142). The IDH1 mutation leads to gene down-regulation, DNA hypermethylation, increased DNA accessibility and H3K27 hypo-acetylation in two distinct IDH1 mutant over-expression models. The drug screen identified histone deacetylase inhibitors (HDACi) and panobinostat (LBH) more specifically as the most selective compounds to inhibit growth in IDH1 mutant glioma lines. Of the eleven annotated HDAC enzymes (HDAC1-11) only six are expressed in IDH1 mutant glioma tissue samples and patient-derived gliomasphere lines (HDAC1-4, HDAC6, and HDAC9). Lentiviral knock-down experiments revealed that HDAC1 and HDAC6 are the most consistently essential for growth both in vitro and in vivo and target very different gene modules. Knock-down of HDAC1 or HDAC6 in vivo led to a more circumscribed less invasive tumor. The gene dysregulation induced by the IDH1 mutation is wide-spread and only partially reversible by direct IDH1 inhibition. This study identifies HDAC1 and HDAC6 as important and drug-targetable enzymes that are necessary for growth and invasiveness in IDH1 mutant gliomas.

Radiotherapy for Atypical Teratoid/=Rhabdoid Tumor (ATRT) on the Pediatric Proton/Photon Consortium Registry (PPCR)

PURPOSE

Atypical teratoid/rhabdoid tumors (ATRT) of the central nervous system (CNS) are rare tumors with a poor prognosis and variable use of either focal or craniospinal (CSI) radiotherapy (RT). Outcomes on the prospective Pediatric Proton/Photon Consortium Registry (PPCR) were evaluated according to RT delivered.

METHODS

Pediatric patients receiving RT were prospectively enrolled on PPCR to collect initial patient, disease, and treatment factors as well as provide follow-up for patient outcomes. All ATRT patients with evaluable data were included. Kaplan-Meier analyses with log-rank p-values and cox proportional hazards regression were performed.

RESULTS

The PPCR ATRT cohort includes 68 evaluable ATRT patients (median age 2.6 years, range 0.71-15.40) from 2012 to 2021. Median follow-up was 40.8 months (range 3.4-107.7). Treatment included surgery (65% initial gross total resection or GTR), chemotherapy (60% with myeloablative therapy including stem cell rescue) and RT. For patients with M0 stage (n = 60), 50 (83%) had focal RT and 10 (17%) had CSI. Among patients with M + stage (n = 8), 3 had focal RT and 5 had CSI. Four-year overall survival (OS, n = 68) was 56% with no differences observed between M0 and M + stage patients (p = 0.848). Local Control (LC) at 4 years did not show a difference for lower primary dose (50-53.9 Gy) compared to ≥ 54 Gy (73.3% vs 74.7%, p = 0.83). For patients with M0 disease, four-year OS for focal RT was 54.6% and for CSI was 60% (Hazard Ratio 1.04, p = 0.95. Four-year event free survival (EFS) among M0 patients for focal RT was 45.6% and for CSI was 60% (Hazard Ratio 0.71, p = 0.519). For all patients, the 4-year OS comparing focal RT with CSI was 54.4% vs 60% respectively (p = 0.944), and the 4-year EFS for focal RT or CSI was 42.8% vs 51.4% respectively (p = 0.610).

CONCLUSION

The PPCR ATRT cohort found no differences in outcomes according to receipt of either higher primary dose or larger RT field (CSI). However, most patients were M0 and received focal RT. A lower primary dose (50.4 Gy), regardless of patient age, is appealing for further study as part of multi-modality therapy.

FLASH Radiotherapy for the Treatment of Symptomatic Bone Metastases (FAST-01): Protocol for the First Prospective Feasibility Study

BACKGROUND

In preclinical studies, FLASH therapy, in which radiation delivered at ultrahigh dose rates of ≥40 Gy per second, has been shown to cause less injury to normal tissues than radiotherapy delivered at conventional dose rates. This paper describes the protocol for the first-in-human clinical investigation of proton FLASH therapy.

OBJECTIVE

FAST-01 is a prospective, single-center trial designed to assess the workflow feasibility, toxicity, and efficacy of FLASH therapy for the treatment of painful bone metastases in the extremities.

METHODS

Following informed consent, 10 subjects aged ≥18 years with up to 3 painful bone metastases in the extremities (excluding the feet, hands, and wrists) will be enrolled. A treatment field selected from a predefined library of plans with fixed field sizes (from 7.5 cm × 7.5 cm up to 7.5 cm × 20 cm) will be used for treatment. Subjects will receive 8 Gy of radiation in a single fraction-a well-established palliative regimen evaluated in prior investigations using conventional dose rate photon radiotherapy. A FLASH-enabled Varian ProBeam proton therapy unit will be used to deliver treatment to the target volume at a dose rate of ≥40 Gy per second, using the plateau (transmission) portion of the proton beam. After treatment, subjects will be assessed for pain response as well as any adverse effects of FLASH radiation. The primary end points include assessing the workflow feasibility and toxicity of FLASH treatment. The secondary end point is pain response at the treated site(s), as measured by patient-reported pain scores, the use of pain medication, and any flare in bone pain after treatment. The results will be compared to those reported historically for conventional dose rate photon radiotherapy, using the same radiation dose and fractionation.

RESULTS

FAST-01 opened to enrollment on November 3, 2020. Initial results are expected to be published in 2022.

CONCLUSIONS

The results of this investigation will contribute to further developing and optimizing the FLASH-enabled ProBeam proton therapy system workflow. The pain response and toxicity data acquired in our study will provide a greater understanding of FLASH treatment effects on tumor responses and normal tissue toxicities, and they will inform future FLASH trial designs.

TRIAL REGISTRATION

: ClinicalTrials.gov NCT04592887; http://clinicaltrials.gov/ct2/show/NCT04592887.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/41812.

A POETIC Phase II study of continuous oral everolimus in recurrent, radiographically progressive pediatric low-grade glioma

BACKGROUND

To evaluate efficacy, pharmacokinetics (PK) and pharmacodynamics of single-agent everolimus in pediatric patients with radiographically progressive low-grade glioma (LGG).

METHODS

Everolimus was administered at 5 mg/m² once daily as a tablet or liquid for a planned 48-week duration or until unacceptable toxicity or disease progression. Patients with neurofibromatosis type 1 were excluded. PK and pharmacodynamic endpoints were assessed in consenting patients.

RESULTS

Twenty-three eligible patients (median age 9.2 years) were enrolled. All patients received prior chemotherapy (median number of prior regimens two) and/or radiotherapy (two patients). By week 48, two patients had a partial response, 10 stable disease, and 11 clinical or radiographic progression; two discontinued study prior to 1 year (toxicity: 1, physician determination: 1). With a median follow up of 1.8 years (range 0.2-6.7 years), the 2-, 3-, and 5-year progression-free survivals (PFS) were 39 ± 11%, 26 ± 11%, and 26 ± 11%, respectively; two patients died of disease. The 2-, 3-, and 5-year overall survival (OS) were all 93 ± 6%. Grade 1 and 2 toxicities predominated; two definitively related grade 3 toxicities (mucositis and neutropenia) occurred. Grade 4 elevation of liver enzymes was possibly related in one patient. Predose blood levels showed substantial variability between patients with 45.5% below and 18.2% above the target range of 5-15 ng/mL. Pharmacodynamic analysis demonstrated significant inhibition in phospho-S6, 4E-BP1, and modulation of c-Myc expression.

CONCLUSION

Daily oral everolimus provides a well-tolerated, alternative treatment for multiple recurrent, radiographically progressive pediatric LGG. Based on these results, everolimus is being investigated further for this patient population.

The Ikaros1, IKZF1, risk locus for Acute Lymphoblastic Leukemia (ALL) at chromosome 7p12.2 regulates the expression of the FIGNL1 gene

ALL, the most common pediatric cancer, originates from progenitor B-cells in ~85% of cases. IKAROS Family Zinc Finger 1 (IKZF1) is an important locus for ALL. Our goal was to identify the functional variants, thereby nominating a potential causal mechanism for ALL.

We evaluated all 27 genetic polymorphisms in disequilibrium at r2>0.8 with the tag, the most highly associated risk variant at IKZF1 locus. They map to intron 7, 3′ UTR and 3′ flanking sequence of IKZF1. Fidgetin-like protein 1 (FIGNL1) is 45,524 bases from the tag variant and is nominated by eQTL and DNA looping data along with IKZF1 as possible targets. Epstein-Barr virus (EBV) transformed GM12878 cells were transduced with lentiviral vectors for stable expression of fusion proteins dead (d) Cas9-VP64 and activator MS2-p65-HSF1 (synergistic activation mediator (SAM) system). We designed 27 single guide (sg) RNAs, one for each of the 27 variants and evaluated expression perturbation in cells transfected with pools and individual sgRNA. Expression of FIGNL1, but not IKZF1, was convincingly altered in this system. The reduction of FIGNL1 expression by ~50% was isolated to two neighboring variants separated by 1 kb. The risk allele at these variants increases FIGNL1 expression in wild type cells, however in EBV transformed B-cells FIGNL1 expression is decreased. Other data show that the EBV encoded DNA binding co-factor EBNA3C binds at or very near this locus in EBV transformed B cells.

Our results nominate two closely located SNPs in the last intron of IKZF1 as potentially causal variants, controlling the expression of FIGNL1, which ordinarily participates in homologous recombination during DNA double-strand break repair, maintenance of genomic stability and prevention of cancer.

The signaling axis atypical protein kinase C λ/ι-Satb2 mediates leukemic transformation of B-cell progenitors

Epigenetically regulated transcriptional plasticity has been proposed as a mechanism of differentiation arrest and resistance to therapy. BCR-ABL leukemias result from leukemic stem cell/progenitor transformation and represent an opportunity to identify epigenetic progress contributing to lineage leukemogenesis. Primary human and murine BCR-ABL⁺ leukemic progenitors have increased activation of Cdc42 and the downstream atypical protein kinase C (aPKC). While the isoform aPKCζ behaves as a leukemic suppressor, aPKCλ/ι is critically required for oncogenic progenitor proliferation, survival, and B-cell differentiation arrest, but not for normal B-cell lineage differentiation. In vitro and in vivo B-cell transformation by BCR-ABL requires the downregulation of key genes in the B-cell differentiation program through an aPKC λ/ι-Erk dependent Etv5/Satb2 chromatin repressive signaling complex. Genetic or pharmacological targeting of aPKC impairs human oncogenic addicted leukemias. Therefore, the aPKCλ/ι-SATB2 signaling cascade is required for leukemic BCR-ABL⁺ B-cell progenitor transformation and is amenable to non-tyrosine kinase inhibition.

The upstream pathways regulating leukemic transcriptional plasticity for differentiation arrest and resistance to therapy are unclear. Here the authors show that aPKC λ/ι-controls leukemic B-cell precursor differentiation arrest trough RAC/MEK/ERK/SATB2 epigenetic repression

A comparison of safety and efficacy of cytotoxic versus molecularly targeted drugs in pediatric phase I solid tumor oncology trials

BACKGROUND

Prior reviews of phase I pediatric oncology trials involving primarily cytotoxic agents have reported objective response rates (ORRs) and toxic death rates of 7.9-9.6% and 0.5%, respectively. These data may not reflect safety and efficacy in phase I trials of molecularly targeted (targeted) drugs.

METHODS

A systematic review of pediatric phase I solid tumor trials published in 1990-2013 was performed. The published reports were evaluated for patient characteristics, toxicity information, and response numbers.

RESULTS

A total of 143 phase I pediatric clinical trials enrolling 3,896 children involving 53 targeted and 48 cytotoxic drugs were identified. A meta-analysis demonstrated that the ORR is 2.1-fold higher with cytotoxic drugs (0.066 vs. 0.031 per subject; P = 0.007). By contrast, the pooled estimate of the stable disease rate (SDR) is similar for cytotoxic and targeted drugs (0.2 vs. 0.23 per subject; P = 0.27).  The pooled estimate of the dose-limiting toxicity rate is 1.8-fold larger with cytotoxic drugs (0.24 vs. 0.13 per subject; P = 0.0003). The hematologic grade 3-4 (G3/4) toxicity rate is 3.6-fold larger with cytotoxic drugs (0.43 vs. 0.12 per treatment course; P = 0.0001); however, the nonhematologic G3/4 toxicities and toxic deaths occur at similar rates for cytotoxic and targeted drugs.

CONCLUSIONS

In phase I pediatric solid tumor trials, ORRs were significantly higher for cytotoxic versus targeted agents. SDRs were similar in targeted and cytotoxic drug trials. Patients treated with cytotoxic agents were more likely to experience hematologic G3/4 toxicities than those patients receiving targeted drugs.

Increasing Activities of Daily Living Is as Easy as 1-2-3

Background: Human flora are the most common cause of bacteremia in immunocompromised patients. Activities of daily living (ADL), including oral care and daily chlorhexidine gluconate bathing, can lower the risk of infection. Methods: To address ADL compliance in our pediatric oncology and bone marrow transplant patients, we adopted the ADL 1-2-3 initiative: daily chlorhexidine gluconate bath and linen change, at least 2 activities per day, and oral care 3 times per day. Using the Model for Improvement we created a standardized ADL process that involved all providers. Interventions included addressing ADL 1-2-3 compliance during rounds, establishing accountability in care delivery, an oral care order set and algorithm, daily text message reminders, and physician intervention with noncompliant and high-risk patients. Results: With our interventions, we increased our median compliance with the all-or-none ADL 1-2-3 initiative from 25% to 66% in 90 days. We have sustained our median compliance to 75% sixteen months after implementation. The greatest impact on compliance was seen with text message reminders to staff to complete and document the ADL 1-2-3 components, designated roles and responsibilities, and physician discussion with noncompliant and high-risk patients. Discussion: Oral care algorithm and order set, daily text message reminders, and physician intervention with noncompliant and high-risk patients has improved our compliance. Units where compliance with ADL participation is low can benefit from incorporating elements from this ADL 1-2-3 initiative.

Increasing the efficiency of trial-patient matching: automated clinical trial eligibility pre-screening for pediatric oncology patients

Background

Manual eligibility screening (ES) for a clinical trial typically requires a labor-intensive review of patient records that utilizes many resources. Leveraging state-of-the-art natural language processing (NLP) and information extraction (IE) technologies, we sought to improve the efficiency of physician decision-making in clinical trial enrollment. In order to markedly reduce the pool of potential candidates for staff screening, we developed an automated ES algorithm to identify patients who meet core eligibility characteristics of an oncology clinical trial.

Methods

We collected narrative eligibility criteria from ClinicalTrials.gov for 55 clinical trials actively enrolling oncology patients in our institution between 12/01/2009 and 10/31/2011. In parallel, our ES algorithm extracted clinical and demographic information from the Electronic Health Record (EHR) data fields to represent profiles of all 215 oncology patients admitted to cancer treatment during the same period. The automated ES algorithm then matched the trial criteria with the patient profiles to identify potential trial-patient matches. Matching performance was validated on a reference set of 169 historical trial-patient enrollment decisions, and workload, precision, recall, negative predictive value (NPV) and specificity were calculated.

Results

Without automation, an oncologist would need to review 163 patients per trial on average to replicate the historical patient enrollment for each trial. This workload is reduced by 85% to 24 patients when using automated ES (precision/recall/NPV/specificity: 12.6%/100.0%/100.0%/89.9%). Without automation, an oncologist would need to review 42 trials per patient on average to replicate the patient-trial matches that occur in the retrospective data set. With automated ES this workload is reduced by 90% to four trials (precision/recall/NPV/specificity: 35.7%/100.0%/100.0%/95.5%).

Conclusion

By leveraging NLP and IE technologies, automated ES could dramatically increase the trial screening efficiency of oncologists and enable participation of small practices, which are often left out from trial enrollment. The algorithm has the potential to significantly reduce the effort to execute clinical research at a point in time when new initiatives of the cancer care community intend to greatly expand both the access to trials and the number of available trials.

Electronic supplementary material

The online version of this article (doi:10.1186/s12911-015-0149-3) contains supplementary material, which is available to authorized users.

Sirolimus for progressive neurofibromatosis type 1-associated plexiform neurofibromas: a neurofibromatosis Clinical Trials Consortium phase II study

BACKGROUND

Plexiform neurofibromas (PNs) are benign peripheral nerve sheath tumors that arise in one-third of individuals with neurofibromatosis type 1 (NF1). They may cause significant disfigurement, compression of vital structures, neurologic dysfunction, and/or pain. Currently, the only effective management strategy is surgical resection. Converging evidence has demonstrated that the NF1 tumor suppressor protein, neurofibromin, negatively regulates activity in the mammalian Target of Rapamycin pathway.

METHODS

We employed a 2-strata clinical trial design. Stratum 1 included subjects with inoperable, NF1-associated progressive PN and sought to determine whether sirolimus safely and tolerably increases time to progression (TTP). Volumetric MRI analysis conducted at regular intervals was used to determine TTP relative to baseline imaging.

RESULTS

The estimated median TTP of subjects receiving sirolimus was 15.4 months (95% CI: 14.3-23.7 mo), which was significantly longer than 11.9 months (P < .001), the median TTP of the placebo arm of a previous PN clinical trial with similar eligibility criteria.

CONCLUSIONS

This study demonstrated that sirolimus prolongs TTP by almost 4 months in patients with NF1-associated progressive PN. Although the improvement in TTP is modest, given the lack of significant or frequent toxicity and the availability of few other treatment options, the use of sirolimus to slow the growth of progressive PN could be considered in select patients.

Sirolimus for non-progressive NF1-associated plexiform neurofibromas: an NF clinical trials consortium phase II study

BACKGROUND

Patients with Neurofibromatosis Type 1 (NF1) have an increased risk of developing tumors of the central and peripheral nervous system, including plexiform neurofibromas (PN), which are benign nerve sheath tumors that are among the most debilitating complications of NF1. There are no standard treatment options for PN other than surgery, which is often difficult due to the extensive growth and invasion of surrounding tissues. Mammalian Target of Rapamycin (mTOR) acts as a master switch of cellular catabolism and anabolism and controls protein translation, angiogenesis, cell motility, and proliferation. The NF1 tumor suppressor, neurofibromin, regulates the mTOR pathway activity. Sirolimus is a macrolide antibiotic that inhibits mTOR activity.

PROCEDURE

We conducted a 2-stratum phase II clinical trial. In stratum 2, we sought to determine whether the mTOR inhibitor sirolimus in subjects with NF1 results in objective radiographic responses in inoperable PNs in the absence of documented radiographic progression at trial entry.

RESULTS

No subjects had better than stable disease by the end of six courses. However, the children's self-report responses on health-related quality of life questionnaires indicated a significant improvement in the mean scores of the Emotional and School domains from baseline to 6 months of sirolimus.

CONCLUSIONS

This study efficiently documented that sirolimus does not cause shrinkage of non-progressive PNs, and thus should not be considered as a treatment option for these tumors. This study also supports the inclusion of patient-reported outcome measures in clinical trials to assess areas of benefit that are not addressed by the medical outcomes.

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

BACKGROUND

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 Children's Cancer Group (CCG) and Children's Oncology Group (COG).

METHODS

Data were combined from the CCG-2891, CCG-2941, CCG-2961, and AAML03P1 trials. The data set included 1840 patients, comprising 238 AYA and 1602 younger patients.

RESULTS

Overall survival was not significantly different in the 2 groups (AYA, 49% ± 7% versus younger, 54% ± 3% (± 2 standard errors), P = .058). Relapse was lower in AYA patients (30% ± 7% versus 41% ± 3%, P = .002), but treatment-related mortality (TRM) was higher (25% ± 6% versus 12% ± 2%, P < .001). After adjustment for other factors, older age remained strongly associated with TRM (hazard ratio = 2.30, 95% CI = 1.59-3.33, P < .001). Infection accounted for the excess TRM in AYA patients.

CONCLUSIONS

Survival in AYA and younger patients with newly diagnosed AML is similar; however, older patients are at higher risk for TRM. More effective strategies for preventing mortality from infection in AYA patients are needed.

Phase I/II trial of clofarabine and cytarabine in children with relapsed/refractory acute lymphoblastic leukemia (AAML0523): a report from the Children's Oncology Group

BACKGROUND

The discovery of effective re-induction regimens for children with more than one relapse of acute lymphoblastic leukemia (ALL) remains elusive. The novel nucleoside analog clofarabine exhibits modest single agent efficacy in relapsed ALL, though optimal combinations of this agent with other active chemotherapy drugs have not yet been defined. Herein we report the response rates of relapsed ALL patients treated on Children's Oncology Group study AAML0523, a Phase I/II study of the combination of clofarabine and cytarabine.

PROCEDURE

AAML0523 enrolled 21 children with ALL in second or third relapse, or those refractory to re-induction therapy. The study consisted of two phases: a dose finding phase and an efficacy phase. The dose finding portion consisted of a single dose escalation/de-escalation of clofarabine for 5 days in combination with a fixed dose of cytarabine (1 g/m(2)/day for 5 days). Eight patients received clofarabine at 40 mg/m(2)/day and 13 patients at 52 mg/m(2)/day.

RESULTS

Toxicities observed at all doses of clofarabine were typical of intensive chemotherapy regimens for leukemia, with infection being the most common. We did not observe significant hepatotoxicity as reported in other clofarabine combination regimens. The recommended pediatric Phase II dose of clofarabine in combination with cytarabine for the efficacy portion of AAML0523 was 52 mg/m(2). Of 21 patients with ALL, 3 (14%) achieved a complete response (CR). Based on the two-stage design definition of first-stage inactivity, the therapy was deemed ineffective.

CONCLUSION

The combination of clofarabine and cytarabine in relapsed/refractory childhood ALL does not warrant further clinical investigation.

Children's Oncology Group's 2013 blueprint for research: adolescent and young adult oncology

The discipline of Adolescent and Young Adult (AYA) Oncology addresses compelling medical and psychosocial needs of AYA patients across the spectrum of cancer survivorship. To be successful, extraordinary collaboration involving multiple scientific disciplines and specialties is required. While AYA Oncology is international in scope, recent AYA-focused studies conducted in the Children's Oncology Group (COG) have documented survival disparities, toxicity differences, and biological insights that provide the basis for new COG trials and initiatives for this population. This experience will be useful in leveraging the new United States National Cancer Institute Clinical Trials Network to transform AYA Oncology research.

Phase I study of paclitaxel with standard dose ifosfamide in children with refractory solid tumors: a Pediatric Oncology Group study (POG 9376)

PURPOSE

A dose-escalation Phase I study of taxol (paclitaxel) administered in combination with standard dose ifosfamide was conducted in children with relapsed or refractory solid tumors. Primary objectives were to estimate the maximum tolerated dose (MTD) and to describe the dose-limiting toxicities (DLTs).

PATIENTS AND METHODS

Paclitaxel was administered as a 6-hr continuous infusion (hr 0-6), followed by intravenous ifosfamide (2 g/m(2)/day x 3 days) over 1 hr at hours 6-7, 24-25, and 48-49. Patients at dose level 1 received 250 mg/m(2) paclitaxel. Subsequent dose escalation proceeded using a standard 3 x 3 Phase I design.

RESULTS

Fifteen patients received a combined 46 courses of therapy. The median age was 14.5 years (range, 2-19 years), and diagnoses included sarcoma (7), neuroblastoma (3), and other (5). Three patients received paclitaxel at 250 mg/m(2) (10 courses), six at 325 mg/m(2) (19 courses), three at 425 mg/m(2) (8 courses), and three at 550 mg/m(2) (9 courses). DLTs occurred in 2/3 patients at 550 mg/m(2) paclitaxel during cycle 1, including grade 3 hypotension and grade 4 anaphylaxis in 1 patient each. Common non-dose-limiting toxicities included bone marrow suppression and peripheral neuropathy. Response was evaluable in 14 patients and included mixed response (3), stable disease (5), and progressive disease (6).

CONCLUSION

Paclitaxel hypersensitivity reactions were dose limiting when the drug was administered as a 6-hr infusion. The MTD and recommended Phase II dose of paclitaxel administered as a 6-hr continuous intravenous infusion followed by standard dose intravenous ifosfamide is 425 mg/m(2) paclitaxel.

Cytidine deaminase genotype and toxicity of cytosine arabinoside therapy in children with acute myeloid leukemia

Cytosine arabinoside (ara-C) is irreversibly deaminated to a non-toxic metabolite by cytidine deaminase (CDA). A common polymorphism, A79C, in the gene encoding cytidine deaminase (CDA) changes a lysine residue to glutamine resulting in decreased enzyme activity. CDA A79C genotypes were determined in 457 children with acute myeloid leukaemia (AML) treated on the Children's Cancer Group (CCG) 2941 and 2961 protocols and analyzed the impact of CDA genotype on therapy outcomes. Postinduction treatment-related mortality (TRM) was significantly elevated in children with the CC genotype (5-year TRM 17 +/- 13% CC vs. 7 +/- 4% AA, 5 +/- 4% AC, P = 0.05). This was more notable in children who received idarubicin, fludarabine, ara-C, and granulocyte colony-stimulating factor (IDA-FLAG; ara-C = 7590 mg/m2) (5-year TRM 24 +/- 21% CC vs. 6 +/- 6% AA, 6 +/- 7% AC, P = 0.07) as consolidation therapy compared to idarubicin, dexamethasone, cytarabine, thioguanine, etoposide and daunomycin (IDA-DCTER; ara-C = 800 mg/m2) (5-year TRM 15 +/- 20% CC vs. 8 +/- 6% AA, 4 +/- 6% AC; P = 0.29). Relapse-free survival was non-significantly increased in children with the CC genotype treated with IDA-FLAG (76 +/- 20% CC vs. 59 +/- 12% AA and 55 +/- 14% AC; P = 0.40). These data indicate that children with a low activity CDA genotype are at increased risk of TRM with ara-C based therapy for AML.

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.

Ethnicity and survival in childhood acute myeloid leukemia: a report from the Children's Oncology Group

We evaluated differences in outcome by ethnicity among children with acute myeloid leukemia (AML). We analyzed 791 children in the CCG 2891 trial and confirmed positive findings in 850 children in the CCG 2961 trial. Hispanic and black children treated with chemotherapy in CCG 2891 had significantly inferior overall survival (OS) from study entry compared with white children (37%+/- 9% vs 48%+/- 4% [P = .016] and 34% +/- 10% vs 48% +/- 4%, [P = .007], respectively). Significantly fewer black children had related donors. Analyses of CCG 2961 confirmed that black children had significantly decreased OS rates compared with white children (45% +/- 12% vs 60% +/- 4%; P = .007) The difference in OS rates between Hispanic and white children approached statistical significance (51% +/- 8% vs 60% +/- 4%; P = .065) Only 7.5% of black children on CCG 2961 had an available family donor. In conclusion, Hispanic and black children with AML have worse survival than white children. Access to chemotherapy, differences in supportive care or leukemia phenotype, and reduced compliance are unlikely explanations for this difference because therapy was given intravenously according to CCG protocols. Fewer black children than expected had an available family marrow donor.

Translocation (8;18;16)(p11;q21;p13). A new variant of t(8;16)(p11;p13) in acute monoblastic leukemia: case report and review of the literature

A complex three-way t(8;18;16)(p11;q21;p13) was detected in a 15-month-old patient with acute myeloid leukemia (AML). The patient had typical clinical manifestation and bone marrow features of AML subtype M5b associated with t(8;16)(p11;p13). Therefore, we believe that the t(8;18;16) is a new variant of t(8;16) related to AML M4/M5. We also review other t(8;16)(p11;p13) variants reported in the literature.

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.

XRCC1 and glutathione-S-transferase gene polymorphisms and susceptibility to radiotherapy-related malignancies in survivors of Hodgkin disease

BACKGROUND

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.

METHODS

In the current study, the authors investigated the association between polymorphisms in 3 genes--glutathione-S-transferase M1 (GSTM1), glutathione-S-transferase T1 (GSTT1), and XRCC1, with roles in protection from a variety of DNA-damaging agents-and the risk of subsequent malignancy in 650 survivors of HD enrolled in the Childhood Cancer Survivor Study who had received radiotherapy.

RESULTS

Individuals lacking GSTM1 but not GSTT1 were at increased risk of any subsequent malignancy (odds ratio [OR], 1.5; 95% confidence interval [CI], 1.0-2.3), and for subsequent cancer within the radiation field (OR, 1.4; 95% CI, 0.9-2.1). A nonsignificant increased risk of thyroid carcinoma was observed in individuals lacking either GSTM1 (OR, 2.9; 95% CI, 0.8-10.9) or GSTT1 (OR, 3.7; 95% CI, 0.6-23.5). Individuals having the genotype of the arginine/glutamine polymorphism at codon 399 in the XRCC1 gene (R399) showed a nonsignificant increased risk of breast carcinoma compared with those without (OR, 1.4; 95% CI, 0.7-2.7), and a nonsignificant decreased risk against a subsequent thyroid carcinoma (OR, 0.6; 95% CI, 0.2-1.6). No differences in genotype frequencies were observed between survivors with basal cell carcinoma when compared with survivors without a subsequent cancer.

CONCLUSIONS

These data illustrated the potential value of incorporating the collection of genomic DNA in longitudinal cohort studies of populations with well defined, potentially carcinogenic exposures. Evaluation of additional genetic polymorphisms in this cohort may help define genes that influence individual sensitivity to radiotherapy.

Results of treatment for metastatic osteosarcoma with neoadjuvant chemotherapy and surgery

The purpose of the current study was to define the survival outcome variables for the 85 patients with Stage IIB osteosarcoma treated with neoadjuvant chemotherapy at the authors' institution from 1982 to 1997. A minimum 4-year followup or death was a requisite for inclusion. Forty-three patients were relapse-free survivors and 14 had no evidence of disease at followup for an overall survival of 67%. Twenty-nine patients had thoracotomy and nine have no evidence of disease with a minimum 4-year followup from last thoracotomy. The mean time to metastasis after diagnosis for patients presenting with Stage IIB disease was 12.8 months. There was no difference in the survival for any of the three chemotherapy protocols, used during the 15 years included in this analysis. There was a significant relation between length of time to relapse and survival. For each additional year without relapse, there is an 18% increase in chance of survival. In patients who were treated with thoracotomy, the number of metastatic nodules was a significant predictor of survival; specifically, each nodule increased the risk of death by 43%. A favorable outcome in this cohort of patients is related to the length of time between initiation of therapy and diagnosis of metastasis, and the number of metastatic foci.

Autologous stem cell transplantation for high-risk pediatric solid tumors

Many solid tumors exhibit a steep dose-response to alkylating agents, and autologous stem cell transplantation (ASCT) allows escalation of the chemotherapy dose for treatment of high risk solid tumors. We have transplanted 24 children and young adults with relapsed or metastatic solid tumors on two consecutive ASCT protocols consisting primarily (protocol MT 8911) or exclusively (MT 9408) of alkylating agents. The median time to neutrophil engraftment was 21 days in protocol MT 8911 (no prophylactic use of growth factors) and 14 days in MT 9408 (G-CSF, 5 microg/kg, started on day 0). Disease-free survival estimated by the Kaplan-Meier method is 39% (95% CI: 19-59%) at 2 years after transplant and 34% (95% CI: 14-54%) at 4 years after transplant. Six of the nine patients with metastatic or relapsed disease that were transplanted while in complete remission (four patients with Ewing's sarcoma family of tumors and two patients with anaplastic Wilms tumor) are alive and disease-free with a median follow-up of 37 months (range 20-74 months). The estimated 4 year survival for patients receiving a transplant while in high risk remission was 78% (95% CI: 51-100%). In contrast, 13/15 patients that were transplanted while in partial remission died because of progressive disease or transplant-related complications. There were three transplant-related deaths (12.5%), including one patient with multiorgan failure, and two patients with complications of hepatic veno-occlusive disease. Our data indicate that autologous stem cell transplantation should be considered for consolidation therapy of high risk and relapsed pediatric patients with solid tumors who have achieved complete remission.

Biphenotypic leukemia: immunologic and morphologic evidence for a common lymphoid-myeloid progenitor in humans

A 5-year-old white girl had a white blood cell count of 80,000/cu mm and 82% lymphoblasts in the peripheral blood. Acute lymphocytic leukemia (ALL) was diagnosed, defined by typical morphology (FAB-L1), a positive reaction for terminal deoxynucleotidyl transferase (TdT) and characteristic surface antigens detected with lymphoid monoclonal antibodies. The patient's peripheral lymphoblast count fell rapidly with ALL therapy, but the WBC count began to rise unexpectedly on the sixth day of treatment, with 84% myeloblasts and monocytoid blasts. Malignant cells in the bone marrow showed FAB-M4 morphology and were no longer reactive with antibodies directed against TdT or common ALL antigen. However, the myeloblasts continued to react with some of the same monoclonal antibodies as the original leukemia cells, and in addition expressed new determinants detected by monoclonal antibody TA-1 and peanut agglutinin. The rapid dynamic evolution of the malignancy during the course of induction chemotherapy favors the existence of a stem cell capable of differentiation into both lymphoid and myeloid clones that are both independently and selectively sensitive to specific chemotherapeutic regimens.