Rationale: The ability of patients with central hypoventilation syndrome (CHS) to produce and process mechanoreceptor signals is unknown.
Objectives: Children with CHS hypoventilate during sleep, although they generally breathe adequately during wakefulness. Previous studies suggest that they have compromised central integration of afferent stimuli, rather than abnormal sensors or receptors. Cortical integration of afferent mechanical stimuli caused by respiratory loading or upper airway occlusion can be tested by measuring respiratory-related evoked potentials (RREPs). We hypothesized that patients with CHS would have blunted RREP during both wakefulness and sleep.
Methods: RREPs were produced with multiple upper airway occlusions and were obtained during wakefulness, stage 2, slow-wave, and REM sleep. Ten patients with CHS and 20 control subjects participated in the study, which took place at the Children's Hospital of Philadelphia. Each patient was age- and sex-matched to two control subjects. Wakefulness data were collected from 9 patients and 18 control subjects.
Measurements and Main Results: During wakefulness, patients demonstrated reduced Nf and P300 responses compared with control subjects. During non-REM sleep, patients demonstrated a reduced N350 response. In REM sleep, patients had a later P2 response.
Conclusions: CHS patients are able to produce cortical responses to mechanical load stimulation during both wakefulness and sleep; however, central integration of the afferent signal is disrupted during wakefulness, and responses during non-REM are damped relative to control subjects. The finding of differences between patients and control subjects during REM may be due to increased intrinsic excitatory inputs to the respiratory system in this state.
central hypoventilation syndrome; respiratory-related evoked potentials; wakefulness; sleep
MLN0128 is an investigational small molecule ATP-competitive inhibitor of the serine/threonine kinase mTOR. MLN0128 was tested against the in vitro panel at concentrations ranging from 0.1 nM to 1 μM and against the PPTP in vivo panels at a dose of 1 mg/kg administered orally daily x 28. In vitro the median relative IC50 concentration was 19 nM. In vivo MLN0128 induced significant differences in EFS in 24/31 (77%) solid tumor models, but 0/7 ALL xenografts. The modest activity observed for MLN0128 against the PPTP preclinical models is similar to that previously reported for another TOR kinase inhibitor.
Preclinical Testing; Developmental Therapeutics; mTOR inhibitor
PF-03084014, a γ-secretase inhibitor, was tested against the PPTP in vitro cell line panel (1.0 nM to 10 μM) and against the in vivo xenograft panels (administered orally twice daily on days 1–7 and 15–21). PF-03084014 demonstrated limited in vitro activity, with no cell line achieving ≥50% inhibition. PF-03084014 induced significant differences in EFS distribution in 14 of 35 (40%) solid tumor xenografts, and 1 of 9 ALL xenografts (which lacked a NOTCH1 mutation), but objective responses were not observed. PF-03084014 demonstrated limited single agent activity in vitro and in vivo against the pediatric preclinical models studied.
Preclinical Testing; Developmental Therapeutics; Notch inhibitors
IMGN901 (lorvotuzumab mertansine) is an antibody-drug conjugate composed of a humanized antibody that specifically binds to CD56 (NCAM, neural cell adhesion molecule) and that is conjugated to the maytansinoid, DM1 (a microtubule targeting agent).
IMGN901 and DM1-SMe (unconjugated DM1 as a mixed disulfide with thiomethane to cap its sulfhydryl group) were tested in vitro at concentrations ranging from 0.01 nM to 0.1 μM and 0.3 pM to 3 nM, respectively. IMGN901 was tested against a subset of PPTP solid tumor xenografts focusing on those with high CD56 expression.The combination of IMGN901 with topotecan was also evaluated.
Neuroblastoma models expressed CD56 at or above the median expression level for all PPTP xenografts and cell lines. Neuroblastoma cell lines demonstrated relatively low sensitivity to DM1-SMe compared to other cell lines, but the sensitivity of neuroblastoma cell lines to IMGN901 was comparable to that of non-neuroblastoma cell lines. In vivo, objective responses were observed in 9 of 24 (38%) models including, 3 of 7 neuroblastoma xenografts, and 2 of 7 rhabdomyosarcoma xenografts. All xenografts with objective responses showed homogeneous high-level staining by IHC for CD56, but not all xenografts with homogenous high-level staining had objective responses. Combined with topotecan, IMGN901 demonstrated therapeutic enhancement against 2 of 4 neuroblastoma models.
IMGN901 has anti-tumor activity against some CD56 expressing pediatric cancer models. High expression of CD56 is a biomarker for in vivo response, but resistance mechanisms to IMGN901 in some high CD56 expressing lines need to be defined.
Preclinical Testing; Developmental Therapeutics; antibody-maytansinoid conjugate; microtubules
Lenalidomide, a novel immunomodulatory agent, is reported to modulate stem cell differentiation, and have direct antiproliferative activity as well as inhibit inflammation and hyperalgesia. On the basis of this varied pharmacological profile, lenalidomide is under investigation as a treatment for a range of oncologic indications.
Lenalidomide was evaluated against the PPTP in vitro panel using 96 hour exposure at concentrations ranging from 1 nM to 10 μM. It was tested against the PPTP in vivo panels at a dose of 30 mg/kg administered orally (PO) oncedaily for a planned for 6 weeks.
In vitro activity was not observed at concentrations up to 10 μM. Lenalidomide was well tolerated, and induced significant differences in EFS distribution compared to control in 7 of 37 (18.9%) of the evaluable solid tumor xenografts and in 0 of 8 (0%) of the evaluable ALL xenografts. The best response in the solid tumor panel was PD2 [progressive disease with growth delay (EFS T/C > 1.5)], observed in 4 of 37 (10.8%) solid tumor xenografts. A single ALL xenograft showed a PD2 response.
Direct antiproliferative effects of lenalidomide were not observed in vitro. In vivo lenalidomide demonstrated low activity against tumors in immune-deficient mice. Our results suggest that lenalidomide’s utility in the pediatric clinical setting may depend upon its ability to induce antitumor activity through effects on host immune and stromal cells rather than through direct effects on tumor cells.
Preclinical Testing; Developmental Therapeutics; Lenalidomide
Neuroblastoma is a pediatric cancer that continues to exact significant morbidity and mortality. Recently, a number of cell cycle proteins, particularly those within the Cyclin D/CDK4/CDK6/RB network, have been shown to exert oncogenic roles in neuroblastoma, suggesting that their therapeutic exploitation might improve patient outcomes.
We evaluated the effect of dual CDK4/CDK6 inhibition on neuroblastoma viability using LEE011, a highly specific CDK4/6 inhibitor.
Treatment with LEE011 significantly reduced proliferation in 12 of 17 human neuroblastoma-derived cell lines by inducing cytostasis at nanomolar concentrations (mean IC50 = 307 ± 68 nM in sensitive lines). LEE011 caused cell cycle arrest and cellular senescence that was attributed to dose-dependent decreases in phosphorylated RB and FOXM1, respectively. In addition, responsiveness of neuroblastoma xenografts to LEE011 translated to the in vivo setting in that there was a direct correlation of in vitro IC50 values with degree of subcutaneous xenograft growth delay. While our data indicate that neuroblastomas sensitive to LEE011 were more likely to contain genomic amplification of MYCN (p = 0.01), the identification of additional clinically accessible biomarkers is of high importance.
Taken together, our data show that LEE011 is active in a large subset of neuroblastoma cell line and xenograft models, and supports the clinical development of this CDK4/6 inhibitor as a therapy for patients with this disease.
Neuroblastoma; CDK4; CDK6; LEE011; MYCN
JNJ-26854165 was originally developed as an activator of p53 capable of inducing apoptosis in cancer cell lines. In vitro, JNJ-26854165 demonstrated cytotoxic activity. The ALL cell line panel had a significantly lower median IC50 (0.85 µM) than the remaining cell lines. In vivo JNJ-26854165 induced significant differences in EFS distribution compared to control in 18 of 37 solid tumors and in 5 of 7 of the evaluable ALL xenografts. Objective responses were observed in 4 of 37 solid tumor xenografts, and 2 of 7 ALL xenografts achieved PR or CR. Responses were noted in xenografts with both mutant and wild-type p53.
Preclinical Testing; Developmental Therapeutics; JNJ-26854165
High-risk neuroblastoma is an aggressive malignancy with high rates of treatment failure. We evaluated genetic variants associated with in vitro sensitivity to two derivatives of cyclophosphamide for association with clinical response in a separate replication cohort of neuroblastoma patients (n=2,709). Lymphoblastoid cell lines (LCLs) were exposed to increasing concentrations of 4-hydroperoxycyclophosphamide [4HC n=422] and phosphoramide mustard [PM n=428] to determine sensitivity. Genome-wide association studies (GWAS) were performed to identify single nucleotide polymorphisms (SNPs) associated with 4HC and PM sensitivity. SNPs consistently associated with LCL sensitivity were analyzed for associations with event-free survival in patients. Two linked SNPs, rs9908694 and rs1453560, were found to be associated with PM sensitivity in LCLs across populations and were associated with event-free survival in all patients (P=0.01) and within the high-risk subset (P=0.05). Our study highlights the value of cell-based models to identify candidate variants that may predict response to treatment in patients with cancer.
neuroblastoma; pharmacogenomics; cell-based models; IKZF3; ZPBP2; expression quantitative trait loci
TP53 is the most frequently mutated gene in human malignancies; however, de novo somatic mutations in childhood embryonal cancers such as neuroblastoma are rare. We report on the analysis of three independent case–control cohorts comprising 10290 individuals and demonstrate that rs78378222 and rs35850753, rare germline variants in linkage disequilibrium that map to the 3′ untranslated region (UTR) of TP53 and 5′ UTR of the Δ133 isoform of TP53, respectively, are robustly associated with neuroblastoma (rs35850753: odds ratio [OR] = 2.7, 95% confidence interval [CI] = 2.0 to 3.6, P
combined = 3.43×10−12; rs78378222: OR = 2.3, 95% CI = 1.8 to 2.9, P
combined = 2.03×10−11). All statistical tests were two-sided. These findings add neuroblastoma to the complex repertoire of human cancers influenced by the rs78378222 hypomorphic allele, which impairs proper termination and polyadenylation of TP53 transcripts. Future studies using whole-genome sequencing data are likely to reveal additional rare variants with large effect sizes contributing to neuroblastoma tumorigenesis.
The condensin complex is required for chromosome condensation during mitosis; however, the role of this complex during interphase is unclear. Neuroblastoma is the most common extracranial solid tumor of childhood, and it is often lethal. In human neuroblastoma, MYCN gene amplification is correlated with poor prognosis. This study demonstrates that the gene encoding the condensin complex subunit SMC2 is transcriptionally regulated by MYCN. SMC2 also transcriptionally regulates DNA damage response genes in cooperation with MYCN. Downregulation of SMC2 induced DNA damage and showed a synergistic lethal response in MYCN-amplified/overexpression cells, leading to apoptosis in human neuroblastoma cells. Finally, this study found that patients bearing MYCN-amplified tumors showed improved survival when SMC2 expression was low. These results identify novel functions of SMC2 in DNA damage response, and we propose that SMC2 (or the condensin complex) is a novel molecular target for the treatment of MYCN-amplified neuroblastoma.
condensin complex; DNA damage response; MYCN; neuroblastoma; synergistic lethal response
Prognostic effects of Mitosis-Karyorrhexis Index (MKI) used in the International Neuroblastoma Pathology Classification (INPC) are age-dependent. A total of 4,282 neuroblastomas reviewed at the Children’s Oncology Group Neuroblastoma Pathology Reference Laboratory (8/1/2001–3/31/2012) included 2,365 low-MKI (L-MKI), 1,068 intermediate-MKI (I-MKI), and 849 high-MKI (H-MKI) tumors. Cox proportional hazards models were fit to determine age cut-offs at which the relative risk of event/death was maximized in each MKI class. Backward-selected Cox models were fit to determine the prognostic strength of the age cut-offs for survival in the presence of other prognostic factors. The age cut-offs used in the INPC for L-MKI tumors (<60 months, n = 2,710, 84.0% ± 1.0% event-free survival [EFS], 93.8 ± 0.7% overall survival [OS] vs ≥60 months, n = 195, 49.8% ± 4.6% EFS, 71.7% ± 4.1% OS; P < 0.0001) and I-MKI tumors (<18 months, n = 568, 83.8% ± 2% EFS, 93.7% ± 1.3% OS vs ≥18 months, n = 500, 51.4% ± 2.9% EFS, 66.7% ± 2.7% OS; P < 0.0001) were within the effective range for distinguishing prognostic groups. As for H-MKI tumors (no cut-off age in the INPC, 51.0% ± 2.2% EFS, 64.4% ± 2.1% OS), a new cut-off of 3–4 months was suggested (<4 months, n = 38, 82.3% ± 8.4% EFS, 81.8% ± 8.5% OS vs ≥4 months, n = 811, 49.6% ± 2.2% EFS, 63.7% ± 2.1% OS, P = 0.0034 and 0.0437, respectively). Multivariate analyses revealed that cut-offs of 60 and 18 months for L-MKI and I-MKI tumors, respectively, were independently prognostic. However, the cut-off of 4 months for H-MKI tumors did not reach statistical significance in the presence of other factors. The age cut-offs for MKI classes (60 months for L-MKI, 18 months for I-MKI, no cut-off for H-MKI) in the current INPC are reasonable and effective for distinguishing prognostic groups with increased risk of event/death for older patients.
age cut-off; International Neuroblastoma Pathology Classification; mitosis-karyorrhexis index; neuroblastoma; prognosis
Quisinostat (JNJ-26481585) is a second generation pyrimidyl-hydroxamic acid histone deacetylase (HDAC) inhibitor with high cellular potency towards class I and II HDACs. Quisinostat was selected for clinical development as it showed prolonged pharmacodynamic effects in vivo and demonstrated improved single agent antitumoral efficacy compared to other analogs.
Quisinostat was tested against the PPTP in vitro panel at concentrations ranging from 1.0 nM to 10 μM and was tested against the PPTP in vivo panels at a dose of 5 mg/kg (solid tumors) or 2.5 mg/kg (ALL models) administered intraperitoneally daily x 21.
In vitro quisinostat demonstrated potent cytotoxic activity, with T/C% values approaching 0% for all of the cell lines at the highest concentration tested. The median relative IC50 value for the PPTP cell lines was 2.2 nM, (range <1 nM to 19 nM). quisinostat induced significant differences in EFS distribution compared to control in 21 of 33 (64%) of the evaluable solid tumor xenografts and in 4 of 8 (50%) of the evaluable ALL xenografts. An objective response was observed in 1 of 33 solid tumor xenografts while for the ALL panel, two xenografts achieved complete response (CR) or maintained CR, and a third ALL xenograft achieved stable disease.
Quisinostat demonstrated broad activity in vitro, and retarded growth in the majority of solid tumor xenografts studied. The most consistent in vivo activity signals observed were for the glioblastoma xenografts and T-cell ALL xenografts.
Preclinical Testing; Developmental Therapeutics; HDAC inhibitor
PR-104 is rapidly hydrolyzed to PR-104A in vivo, which is activated by reduction to the corresponding 5-hydroxylamine (PR-104H) and amine (PR-104M) to produce DNA interstrand cross-links. PR-104 activation can occur via hypoxia-dependent reductases and also independently of hypoxia by aldo-keto reductase (AKR) 1C3.
PR-104A was tested against the PPTP in vitro panel (10 nM to 100 μM), and PR-104 in vivo using a weekly × 6 schedule at its maximum tolerated dose (MTD) of 550 mg/kg. Subsequently PR-104 was tested at 270 and 110 mg/kg. Pharmacokinetics for PR-104 and its metabolites were determined, as were levels of AKR1C3 RNA and protein in xenografts.
In vitro, the leukemia models were most sensitive to PR-104A. In vivo, PR-104 induced objective responses at its MTD in 21/34 solid tumor models and maintained complete responses against 7/7 acute lymphoblastic leukemia (ALL) models. At 270 mg/kg and lower dose levels, PR-104 did not induce solid tumor regressions, suggesting a steep dose–response relationship. Pharmacokinetic analysis suggests higher systemic exposures to PR-104A and its metabolites in mice compared to those achievable in patients. Levels of AKR1C3 protein did not correlate with tumor responsiveness.
As monotherapy, PR-104 demonstrated a high level of activity against both solid tumor and ALL models at its MTD, but the activity was almost completely lost at half the MTD dose for solid tumors. Pharmacokinetic data at the PR-104 MTD from human trials suggest that PR-104 metabolites may not reach the plasma exposures in children that were associated with high-level preclinical activity.
developmental therapeutics; preclinical testing; PR-104
AZD8055 is a small molecule ATP-competitive inhibitor of the serine/threonine kinase mTOR that regulates cap-dependent translation through the mTORC1 complex and Akt activation through the mTORC2 complex.
AZD8055 was tested against the PPTP in vitro panel at concentrations ranging from 1.0 nM to 10 μM and against the PPTP in vivo panels at a dose of 20 mg/kg administered orally daily × 7 for 4 weeks.
In vitro the median relative IC50 for AZD8055 against the PPTP cell lines was 24.7 nM. Relative I/O values >0% (consistent with a cytostatic effect) were observed in 8 cell lines and 15 cell lines showed Relative I/O values ranging from −4.7 to −92.2% (consistent with varying degrees of cytotoxic activity). In vivo AZD8055 induced significant differences in EFS distribution compared to controls in 23 of 36 (64%) evaluable solid tumor xenografts, and 1 of 6 evaluable ALL xenografts. Intermediate activity for the time to event activity measure (EFS T/C >2) was observed in 5 of 32 (16%) solid tumor xenografts evaluable. The best response was stable disease. PD2 (progressive disease with growth delay) was observed in 20 of 36 (55.6%) evaluable solid tumor xenografts. AZD8055 significantly inhibited 4E-BP1, S6, and Akt phosphorylation following day 1 and day 4 dosing, but suppression of mTORC1 or mTORC2 signaling did not predict tumor sensitivity.
AZD8055 demonstrated broad activity in vitro, but at the dose and schedule studied demonstrated limited activity in vivo against the PPTP solid tumor and ALL panels.
developmental therapeutics; mTOR inhibitor; preclinical testing
Volasertib (BI 6727) is a potent inhibitor of Polo-like kinase 1 (Plk1), that is overexpressed in several childhood cancers and cell lines. Because of its novel mechanism of action, volasertib was evaluated through the PPTP.
Volasertib was tested against the PPTP in vitro cell line panel at concentrations from 0.1 nM to 1.0 μM and against the PPTP in vivo xenograft panels administered I.V at a dose of 30 mg/kg (solid tumors) or 15 mg/kg (ALL models) using a q7dx3 schedule.
In vitro volasertib demonstrated cytotoxic activity, with a median relative IC50 value of 14.1 nM, (range 6.0 nM to 135 nM). Volasertib induced significant differences in EFS in 19 of 32 (59%) of the evaluable solid tumor xenografts and in 2 of 4 (50%) of the evaluable ALL xenografts. Volasertib induced tumor growth inhibition meeting criteria for intermediate EFS T/C (>2) activity in 11 of 30 (37%) evaluable solid tumor xenografts, including neuroblastoma (4 of 6) and glioblastoma (2 of 3) panels, and 2 of 4 ALL models. Objective responses (CR’s) were observed for 4 of 32 solid tumor (2 neuroblastoma, 1 glioblastoma, and 1 rhabdomyosarcoma) and 1 of 4 ALL xenografts.
Volasertib shows potent in vitro activity against the PPTP cell lines with no histotype selectivity. In vivo, volasertib induced regressions in several xenograft models. However, pharmacokinetic data suggest that mice tolerate higher systemic exposure to volasertib than humans, suggesting that the current results may over-estimate potential clinical efficacy against the childhood cancers studied.
Preclinical Testing; Developmental Therapeutics; Plk inhibitor
BMS-754807 is a small molecule ATP-competitive inhibitor of the type-1 insulin-like growth factor receptor currently in phase 1 clinical trials.
BMS-754807 was tested against the Pediatric Preclinical Testing Program (PPTP) in vitro panel at concentrations ranging from 1.0 nM to 10 μM and was tested against the PPTP in vivo panels at a dose of 25 mg/kg administered orally BID for 6 days, repeated for 6 weeks.
In vitro BMS-754807 showed a median EC50 value of 0.62 μM against the PPTP cell lines. The median EC50 for the four Ewing sarcoma cell lines was less than that for the remaining PPTP cell lines (0.19 μM vs. 0.78 μM, P = 0.0470). In vivo BMS-754807 induced significant differences in EFS distribution compared to controls in 18 of 32 evaluable solid tumor xenografts (56%) tested, but in none of the ALL xenografts studied. Criteria for intermediate activity for the time to event activity measure (EFS T/C >2) were met in 7 of 27 solid tumor xenografts evaluable for this measure. The best response was PD2 (progressive disease with growth delay), which was observed in 18 of 32 solid tumor xenografts. PD2 responses were most commonly observed in the rhabdomyosarcoma, neuroblastoma, osteosarcoma, Ewing sarcoma, and Wilms tumor panels.
BMS-754807 activity in vitro is consistent with a specific IGF-1R effect that has half-maximal response in the 0.1 μM range and that is observed in a minority of the PPTP cell lines. In vivo intermediate activity was most commonly observed in the neuroblastoma and rhabdomyosarcoma panels.
developmental therapeutics; IGF-1 receptor inhibitor; preclinical testing
Antimitotic agents are essential components for curative therapy of pediatric acute leukemias and many solid tumors. Eribulin is a novel agent that differs from both Vinca alkaloids and taxanes in its mode of binding to tubulin polymers.
Eribulin was tested against the PPTP in vitro cell line panel at concentrations from 0.1 nM to 1.0 μM and against the PPTP in vivo xenograft panels at a dose of 1 mg/kg (solid tumors) or 1.5 mg/kg (ALL models) using a q4dx3 schedule repeated at Day 21.
In vitro eribulin demonstrated cytotoxic activity, with a median relative IC50 value of 0.27 nM, (range <0.1–14.8 nM). Eribulin was well tolerated in vivo, and all 43 xenograft models were considered evaluable for efficacy. Eribulin induced significant differences in event-free survival (EFS) distribution compared to control in 29 of 35 (83%) of the solid tumors and in 8 of 8 (100%) of the ALL xenografts. Objective responses were observed in 18 of 35 (51%) solid tumor xenografts. Complete responses (CR) or maintained CR were observed in panels of Wilms tumor, Ewing sarcoma, rhabdomyosarcoma, glioblastoma, and osteosarcoma xenografts. All eight ALL xenografts achieved CR or MCR.
The high level of activity observed for eribulin against the PPTP preclinical models makes this an interesting agent to consider for pediatric evaluation. The activity pattern observed for eribulin in the solid tumor panels is equal or superior to that observed previously for vincristine.
developmental therapeutics; PI3K inhibitor; preclinical testing
The PIM kinase inhibitor, SGI-1776, was tested against the PPTP in vitro (1.0 nM to 10 μM) and in vivo panels (148 mg/kg daily x 5 days for 3 weeks). SGI-1776 exhibited cytotoxic activity in vitro with a median relative IC50 of 3.1 μM. SGI-1776 induced significant differences in EFS distribution in vivo in 9 of 31 solid tumor xenografts and in 1 of 8 of the evaluable ALL xenografts. SGI-1776 induced tumor growth inhibition meeting criteria for intermediate EFS T/C activity in 1 of 39 evaluable models. In contrast, SGI-1776 induced complete responses of subcutaneous MV4;11 (B myeloid leukemia).
Preclinical Testing; Developmental Therapeutics; kinase inhibitors
The DNA methylating agent temozolomide was developed primarily for treatment of glioblastoma. However, preclinical data have suggested a broader application for treatment of childhood cancer. Temozolomide was tested against the PPTP solid tumor and ALL models.
Temozolomide was tested against the PPTP in vitro panel at concentrations ranging from 0.1 to 1,000 μM and was tested against the PPTP in vivo panels at doses from 22 to 100 mg/kg administered orally daily for 5 days, repeated at day 21.
In vitro temozolomide showed cytotoxicity with a median relative IC50 (rIC50) value of 380 μM against the PPTP cell lines (range 1 to > 1,000 μM). The three lines with rIC50 values lesser than 10 μM had low MGMT expression compared to the remaining cell lines. In vivo temozolomide demonstrated significant toxicity at 100 mg/kg, but induced tumor regressions in 15 of 23 evaluable solid tumor models (13 maintained CR [MCR], 2 CR) and 5 of 8 ALL models (3 MCR, 2 CR). There was a steep dose response curve, with lower activity at 66 mg/kg temozolomide and with tumor regressions at 22 and 44 mg/kg restricted to models with low MGMT expression.
Temozolomide demonstrated high level antitumor activity against both solid tumor and leukemia models, but also elicited significant toxicity at the highest dose level. Lowering the dose of TMZ to more closely match clinical exposures markedly reduced the antitumor activity for many xenograft lines with responsiveness at lower doses closely related to low MGMT expression.
developmental therapeutics; preclinical testing; temodar
Neuroblastoma is an embryonal tumor with contrasting clinical courses. Despite elaborate stratification strategies, precise clinical risk assessment still remains a challenge. The purpose of this study was to develop a PCR-based predictor model to improve clinical risk assessment of patients with neuroblastoma.
The model was developed using real-time PCR gene expression data from 96 samples and tested on separate expression data sets obtained from real-time PCR and microarray studies comprising 362 patients.
On the basis of our prior study of differentially expressed genes in favorable and unfavorable neuroblastoma subgroups, we identified three genes, CHD5, PAFAH1B1, and NME1, strongly associated with patient outcome. The expression pattern of these genes was used to develop a PCR-based single-score predictor model. The model discriminated patients into two groups with significantly different clinical outcome [set 1: 5-year overall survival (OS): 0.93 ± 0.03 vs. 0.53 ± 0.06, 5-year event-free survival (EFS): 0.85 ± 0.04 vs. 0.042 ± 0.06, both P < 0.001; set 2 OS: 0.97 ± 0.02 vs. 0.61 ± 0.1, P = 0.005, EFS: 0.91 ± 0.8 vs. 0.56 ± 0.1, P = 0.005; and set 3 OS: 0.99 ± 0.01 vs. 0.56 ± 0.06, EFS: 0.96 ± 0.02 vs. 0.43 ± 0.05, both P < 0.001]. Multivariate analysis showed that the model was an independent marker for survival (P < 0.001, for all). In comparison with accepted risk stratification systems, the model robustly classified patients in the total cohort and in different clinically relevant risk subgroups.
We propose for the first time in neuroblastoma, a technically simple PCR-based predictor model that could help refine current risk stratification systems.
TrkB acts as an oncogenic kinase in a subset of human neuroblastomas. Lestaurtinib, a multi-kinase inhibitor with potent activity against Trk kinases, has demonstrated activity in preclinical models of neuroblastoma.
Patients with refractory high-risk neuroblastoma received lestaurtinib twice daily for 5 days out of seven in 28-day cycles, starting at 70% of the adult recommended Phase 2 dose. Lestaurtinib dose was escalated using a 3 + 3 design. Pharmacokinetics and plasma phospho-TrkB inhibitory activity were evaluated in the first cycle.
Forty-seven subjects were enrolled, and 10 dose levels explored starting at 25 mg/M2/dose BID. Forty-six subjects were evaluable for response, and 42 subjects were fully evaluable for determination of dose escalation. Asymptomatic and reversible grade 3–4 transaminase elevation was dose limiting in 4 subjects. Reversible pancreatitis (grade 2) was observed in 3 subjects after prolonged treatment at higher dose levels. Other toxicities were mild and reversible. Pharmacokinetic analyses revealed rapid drug absorption, however inter-patient variability was large. Plasma inhibition of phospho-TrkB activity was observed 1 h post-dosing at 85 mg/M2 with uniform inhibition at 120 mg/M2. There were two partial responses and nine subjects had prolonged stable disease at dose levels ≥ 5, (median: 6 cycles). A biologically effective and recommended phase 2 dose of 120 mg/M2/dose BID was established.
Lestaurtinib was well tolerated in patients with refractory neuroblastoma, and a dose level sufficient to inhibit TrkB activity was established. Safety and signs of activity at the higher dose levels warrant further evaluation in neuroblastoma.
Neuroblastoma; Receptor tyrosine kinase; Targeted therapy; Lestaurtinib; Signal transduction
MicroRNAs are small noncoding RNAs that have critical roles in regulating a number of cellular functions through transcriptional silencing. They have been implicated as oncogenes and tumor suppressor genes (oncomirs) in several human neoplasms. We used an integrated genomics and functional screening strategy to identify potential oncomirs in the pediatric neoplasm neuroblastoma. We first identified microRNAs that map within chromosomal regions that we and others have defined as frequently deleted (1p36, 3p22, and 11q23-24) or gained (17q23) in high-risk neuroblastoma. We then transiently transfected microRNA precursor mimics or inhibitors into a panel of six neuroblastoma cell lines that we characterized for these genomic aberrations. The majority of transfections showed no phenotypic effect, but the miR-34a (1p36) and miR-34c (11q23) mimics showed dramatic growth inhibition in cell lines with 1p36 hemizygous deletion. In contrast, there was no growth inhibition by these mimics in cell lines without 1p36 deletions. Quantitative reverse transcription-PCR showed a perfect correlation of absent miR-34a expression in cell lines with a 1p36 aberration and phenotypic effect after mimetic add-back. Expression of miR-34a was also decreased in primary tumors (n = 54) with 1p36 deletion (P = 0.009), but no mutations were discovered in resequencing of the miR-34a locus in 30 neuroblastoma cell lines. Flow cytometric time series analyses showed that the likely mechanism of miR-34a growth inhibition is through cell cycle arrest followed by apoptosis. BCL2 and MYCN were identified as miR-34a targets and likely mediators of the tumor suppressor phenotypic effect. These data support miR-34a as a tumor suppressor gene in human neuroblastoma.
Ganetespib, an Hsp90 inhibitor, was tested against the PPTP in vitro cell line panel and selected xenografts in vivo, including JAK2- and BRAF-mutated models. Ganetespib demonstrated potent in vitro cytotoxic activity (median rIC50 8.8 nM, range 4.4–27.1 nM). In vivo, ganetespib induced significant differences in EFS distribution for 4 of 11 xenografts. Intermediate activity (EFS T/C > 2) was noted only for the MV4;11 xenograft, and there were no objective responses. Administered as single agents, Hsp90 inhibitors examined by the PPTP have shown limited evidence for a therapeutic window against both solid tumor and leukemia pediatric preclinical models.
Developmental therapeutics; Hsp90 inhibitors; preclinical testing
A phase I study was conducted to determine the maximum-tolerated dose, dose-limiting toxicities (DLTs), and pharmacokinetics of fenretinide (4-HPR) delivered in an oral powderized lipid complex (LXS) in patients with relapsed/refractory neuroblastoma.
4-HPR/LXS powder (352 - 2210 mg/m2/day) was administered on Days 0 – 6, in 21-day courses, by standard 3+3 design.
Thirty-two patients (median age = 8 years, range 3 – 27 years) enrolled with thirty evaluable for dose escalation. Prior therapies included stem cell transplantation/support (n = 26), 13-cis-retinoic acid (n = 22), 125/131I-MIBG (n = 13), and anti-GD2 antibody (n = 6). 170+ courses were delivered. Course 1 DLTs were a Grade 3 (n = 1) alkaline phosphatase at 352 mg/m2/day. Other major toxicities were Grade 4 (n = 1) alkaline phosphatases on Courses 5 and 6 at 774 mg/m2/day, and Grade 3 (n = 1) ALT/AST elevation on Course 2 at 1700 mg/m2/day. Of twenty-nine response-evaluable patients, six had stable disease (SD)(4 – 26 courses); four with marrow- or bone disease-only had complete responses (CR)(10 - 46 courses). 4-HPR plasma levels were several fold higher (P<0.05) than previously reported using capsular fenretinide. The Day 6 mean peak 4-HPR plasma level at 1700 mg/m2/day was 21 μM. An MTD was not reached.
4-HPR/LXS oral powder obtained higher plasma levels, with minimal toxicity and evidence of anti-tumor activity, than a previous capsule formulation. A recommended phase II schedule of 4-HPR/LXS powder is 1500 mg/m2/day, TID, on Days 0 – 6, of a 21-day course.
fenretinide; neuroblastoma; pediatric; powder; Lym-X-Sorb™
Identifying novel therapeutic agents for the treatment of childhood cancers requires preclinical models that recapitulate the molecular characteristics of their respective clinical histotypes.
Experimental Design and Results
Here, we have applied Affymetrix HG-U133Plus2 profiling to an expanded panel of models in the Pediatric Preclinical Testing Program. Profiling led to exclusion of two tumor lines that were of mouse origin and five osteosarcoma lines that did not cluster with human or xenograft osteosarcoma samples. We compared expression profiles of the remaining 87 models with profiles from 112 clinical samples representing the same histologies and show that model tumors cluster with the appropriate clinical histotype, once “immunosurveillance” genes (contributed by infiltrating immune cells in clinical samples) are eliminated from the analysis. Analysis of copy number alterations using the Affymetrix 100K single nucleotide polymorphism GeneChip showed that the models have similar copy number alterations to their clinical counterparts. Several consistent copy number changes not reported previously were found (e.g., gain at 22q11.21 that was observed in 5 of 7 glioblastoma samples, loss at 16q22.3 that was observed in 5 of 9 Ewing’s sarcoma and 4 of 12 rhabdomyosarcoma models, and amplification of 21q22.3 that was observed in 5 of 7 osteosarcoma models). We then asked whether changes in copy number were reflected by coordinate changes in gene expression. We identified 493 copy number – altered genes that are nonrandom and appear to identify histotype-specific programs of genetic alterations.
These data indicate that the preclinical models accurately recapitulate expression profiles and genetic alterations common to childhood cancer, supporting their value in drug development.