Abstract 708: Prohibitin is a prognostic marker of treatment failure and therapeutic target to block chemotherapy resistance in Wilms tumor

Wilms tumor (WT) is the most common kidney tumor of children. Over the last three decades, clinical trials employing multi-modality therapies have resulted in overall survival of greater than 90% for patients with low-risk disease. In spite of these advances, treatment of patients with advanced, anaplastic, and relapsed Wilms tumors remains challenging, with substantial rates of treatment failure and death. To improve risk stratification and identify novel therapeutic targets, we used high-accuracy mass spectrometry urine proteomics to identify urine tumors markers associated with relapsed WT and non-WT renal tumors. We measured urine proteomes at diagnosis of 54 patients with renal WT, clear cell sarcoma, rhabdoid tumor, and age-matched controls, leading to the quantitation of 6,519 urine proteins. In particular, we identified specific urine WT markers, including those that were enriched in patients with relapsed WT, such as mitochondrial regulators prohibitin and DAD1, β-catenin antagonist DACT2, and DNA repair factor SUN1. Using a specific enzyme-linked immunosorbent assay (ELISA) developed to measure urine prohibitin in an independent cohort of 139 WT and control samples, we found that urine prohibitin concentrations over 1000 ng/mL were significantly associated with the risk of disease relapse, with an odds ratio of relapse of 153 and receiver operating characteristic area under the curve of 0.77 (95% confidence interval of 0.64-0.99). Immunohistochemical tumor analysis revealed that prohibitin was highly expressed in primary Wilms tumor specimens. Importantly, using loss- and gain-of-function genetic experiments, we found that prohibitin was required for the growth and survival of Wilms tumor cells, and its overexpression conferred concomitant resistance to vincristine, doxorubicin and actinomycin D. Consistent with prohibitin’s functions in mitochondria, we are using BH3 profiling to elucidate specific intrinsic apoptotic dependencies in distinct subsets of refractory Wilms tumors, as a prelude to rational combination blockade of chemotherapy resistance, such as blockade of BCL2 dependence using venetoclax. In all, the use of urine prohibitin measurements may improve initial therapy stratification, and enable monitoring of response to therapy and early detection of relapse. In addition, therapeutic targeting of chemotherapy resistance induced by prohibitin overexpression may offer improved therapies for patients with relapsed or refractory Wilms tumors.

Citation Format: Michael Vincent Ortiz, Melissa Burns, Amy Eisenberg, Saima Ahmed, Lyvia Gaewsky, Gary Bradwin, Paolo Cifani, Anton Henssen, Ian Macarthur, Michael LaQuaglia, Anthony Letai, Arlene Naranjo, Samantha Gadd, Yueh-Yun Chi, Jeffrey Dome, Elizabeth Perlman, Elizabeth Mullen, Hanno Steen, Alex Kentsis. Prohibitin is a prognostic marker of treatment failure and therapeutic target to block chemotherapy resistance in Wilms tumor [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 708. doi:10.1158/1538-7445.AM2017-708

Phase 1 trial of lyso-thermosensitive liposomal doxorubicin (LTLD) and magnetic resonance guided high intensity focused ultrasound (MR-HIFU) for pediatric refractory solid tumors

TPS10579

Background: Prognosis for children and young adults with refractory solid tumors remains unacceptably poor. Current approaches have reached the limits of maximal dose intensification, and the acute and late side effects of therapy are substantial. MR-HIFU is an innovative therapy that uses an external applicator to focus ultrasound energy inside a tumor non-invasively and without radiation. The resulting heating is precisely controlled and accurately targeted with the aid of MR thermometry and anatomic imaging. The flexibility and control over local heating by MR-HIFU provide an ideal system to be used with LTLD, a novel formulation of liposomal doxorubicin with the unique property of rapid heat-activated release of doxorubicin, an active agent in most pediatric solid tumors. The potential synergistic effects include enhanced permeability of the tumor vasculature, enhanced extravasation of the drug and subsequent high local concentrations of doxorubicin in the targeted tumor, inhibition of DNA repair, and stimulation of immune responses. Methods: This is the first pediatric trial of LTLD with MR-HIFU in refractory solid tumors (NCT02536183). Part A is a phase 1 dose escalation study to determine the maximum tolerated dose (MTD) or recommended phase 2 dose (RP2D) of LTLD combined with MR-HIFU ablation in children. Part B combines LTLD at the MTD/RP2D with MR-HIFU induced mild hyperthermia (MHT) in an expanded cohort. Patients ≤21 (Part A) and ≤30 (Part B) years of age with refractory solid tumors at sites accessible to MR-HIFU, adequate organ function including cardiac function, and prior anthracycline dose of ≤ 450 mg/m2 are eligible. LTLD is administered intravenously over 30 min followed immediately by MR-HIFU on day 1 of a 21-day cycle. Patients can receive a maximum of 6 cycles (or lifetime of 600 mg/m2 of cumulative anthracycline) provided treatment is tolerated and have at least stable disease. Secondary objectives evaluate changes in quality of life and pharmacodynamic immune markers in children treated with LTLD and MR-HIFU. Clinical trial information: NCT02536183.

ADVL1522: A phase 2 study of IMGN901 (lorvotuzumab mertansine; IND# 126953, NSC# 783609) in children with relapsed or refractory Wilms tumor, rhabdomyosarcoma, neuroblastoma, pleuropulmonary blastoma, malignant peripheral nerve sheath tumor (MPNST), and synovial sarcoma: A Children's Oncology Group study

10537

Background: Lorvotuzumab mertansine (IMGN901; LM) is an antibody-drug conjugate, linking anti-mitotic agent (DM1) to an anti-CD56 antibody. Preclinical data show effects in Wilms tumor (WT), rhabdomyosarcoma (RMS), and neuroblastoma (NBL). Synovial sarcoma (SS), MPNST and pleuropulmonary blastoma (PPB) also express CD56. A phase 2 trial assessing the efficacy and tolerability of LM administered at the adult recommended phase 2 dose (RP2D) was conducted in children with relapsed tumors. Methods: LM (110 mg/m2/dose) was administered IV on days (d) 1 and 8 of 21 d cycles, with dexamethasone pre-medication. The tolerability of LM was assessed in 6 patients prior to trial activation group-wide. Dose limiting toxicity (DLT) was assessed using CTCAE. Response was assessed by RECIST. Pharmacokinetics (PK) were obtained during cycle 1. Peripheral blood CD56-positive cells were measured d1 and d8 pre-dose. Tumor CD56 expression by immunohistochemistry in archival tissue was scored (0-3+). Results: Sixty-two patients were enrolled. The median (range) age was 14.3 y (2.8–29.9); 35 were male. Diagnoses included WT (17), RMS (17), NBL (12), SS (10), MPNST (5) and PPB (1). One patient was ineligible due to lack of measurable disease. Of 61 eligible patients, 47 were evaluable for toxicity, 50 for response, 50 for tumor CD56 expression; and 18 consented to optional PK. Five patients experienced 9 DLTs: hyperglycemia (1), colonic fistula (1) with perforation (1), nausea (1) with vomiting (1), increased ALT (2 in cycle 1; 1 in cycle 2 with increased AST (1)). Non-dose limiting toxicities (Grade ≥3) attributed to LM included lymphopenia, anemia, vomiting, dehydration, hypokalemia, hyperuricemia, hypophosphatemia. Mean DM1 Cmax, t1/2 and AUC0-∞values were 922 ng/ml, 33 h and 27400 ng/ml*h, respectively. Tumor CD56 expression was 0 (8%), 1+(4%), 2+(12%), 3+(76%). LM and CD56 antibody PK, and response, will be reported. Conclusions: LM (110 mg/m2) is tolerated in children at the adult RP2D. Clinical trial information: NCT 02452554.

Abstract 1103: Human tumorigenesis induced by endogenous DNA transposase

Recent cancer genome surveys have revealed extremely low rates of coding gene mutations in distinct tumor subtypes, suggesting that alternative mechanisms must contribute to their pathogenesis. Transposons are mobile genetic elements that are found in all living organisms, including humans where they occupy nearly half of the genome. Their mobilization can cause structural rearrangements in normal and cancer cells. However, it remains unknown whether transposition is a cause of cellular transformation or merely a bystander effect of dysregulated gene expression. Here, we report that PGBD5, a recently characterized human gene related to the piggyBac transposase from the cabbage looper moth, is aberrantly expressed in rhabdoid tumors, medulloblastoma, acute leukemias, and some sarcomas and carcinomas. Ectopic expression of PGBD5 in non-transformed primary human cells is sufficient to induce anchorage independence in vitro and penetrant tumor formation in immunodeficient mice in vivo. PGBD5 expression is sufficient to induce genomic mobilization of engineered DNA transposons in human cells, and purified recombinant PGBD5 exhibits transposase domain-dependent endonuclease activity in vitro. Flanking-sequence exponential anchored PCR and massively parallel sequencing of DNA transposon integrations revealed distinct activity on piggyBac-like inverted terminal repeats, and preference for specific euchromatic human genomic loci. This enables mapping of structural rearrangements of endogenous human transposable elements in primary human tumor genomes, some of which target genes involved in cellular transformation. We find that PGBD5 transposase-induced cell transformation is associated with morphologic de-differentiation, induction of distinct Polycomb gene expression programs and structural chromatin remodeling, consistent with its epigenetic control. These findings reveal an unanticipated mechanism of human tumorigenesis, genomic plasticity and structural alterations of non-coding regulatory genomic loci in human cancer.

Citation Format: Anton Henssen, Amy Eisenberg, Eileen Jiang, Elizabeth Henaff, Richard Koche, Melissa Burns, Julianne R. Carson, Gouri Nanjangud, Eric Still, Jorge Gandara, Paolo Cifani, Avantika Dhabaria, Xiaodong Huang, Elisa de Stanchina, Elizabeth Mullen, Hanno Steen, Elizabeth Perlman, Jeffrey Dome, Cristina Antonescu, Cedric Feschotte, Christopher E. Mason, Alex Kentsis. Human tumorigenesis induced by endogenous DNA transposase. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1103. doi:10.1158/1538-7445.AM2015-1103

Prognostic implications of gain of 1q in favorable histology Wilms tumor: A report from the Children’s Oncology Group

10014

Background: Wilms tumor is the most common childhood renal tumor. While the majority of patients with favorable histology Wilms Tumor (FHWT) have good outcomes, many patients still experience recurrence and death from disease. This study’s goal was to determine if chromosome 1q gain is associated with event-free (EFS) and overall survival (OS) in FHWT. Methods: Unilateral FHWT samples were obtained from patients enrolled on National Wilms Tumor Study-4 and Pediatric Oncology Group 9046, “A Molecular Genetic analysis of Wilms Tumor.” 1q gain, 1p loss, and 16q loss were determined using multiplex ligation-dependent probe amplification (MLPA). Results: The eight-year EFS was 87% (95% CI 82%, 91%) for the entire cohort of 212 patients. Tumors of 58/212 patients (27%) displayed 1q gain. A strong relationship between 1q gain and 1p/16q loss was observed. The eight-year EFS was 76% (95% CI 63%, 85%) for those with 1q gain and 93% (95% CI 87%, 96%) for those lacking 1q gain (p=0.0024). The eight-year OS was 89% (95% CI 78%, 95%) for those with 1q gain, and 98% (95% CI 94%, 99%) for those lacking 1q gain (p=0.0075). Gain of 1q did not correlate with disease stage (p=0.16). After stratification for stage, 1q gain was associated with a significant increase in the risk of failure (risk ratio estimate: 2.72, p=0.0089). Conclusions: Gain of 1q is associated with inferior EFS and OS in FHWT and may provide a new and valuable prognostic marker to stratify therapy for patients with FHWT. A confirmatory study is necessary before this biomarker is incorporated into risk stratification schema of future therapeutic studies.

Abstract 1439: Loss of expression of SWI/SNF subunits in high risk Wilms tumor is accompanied by global gene expression changes

Introduction: The TARGET initiative seeks to identify therapeutic targets through genomic sequencing supported by copy number and gene expression analysis. The High Risk Wilms Tumor TARGET project, currently in progress, includes the analysis of favorable histology (FH) tumors that relapsed and tumors with anaplasia (unfavorable histology). We report the identification of a group of Wilms tumors (WT) identified by a unique gene expression pattern. Methods and Results: 102 high risk WT (43 anaplastic, 59 relapsed FH) were analyzed using Affymetrix U133+2 chips. Unsupervised hierarchical analysis consistently selected 9 tumors (5 anaplastic, 4 FH) that shared a striking gene expression pattern. These patients presented at 15-96 months (median 51); 7 had a triphasic histology and 2 were blastemal predominate; 4 died of their disease. When the top differentially expressed genes (P<0.0001) were analyzed with PANTHER, significant repression (p=5x10−7) of genes responsible for the regulation of chromatin architecture was apparent. Among the most significantly down-regulated were ARID1A (fold change (FC) 0.2, p=5.2x10−8) and SMARCA4 (BRG1, FC 0.16 p=9x10−6), among others. Transcriptomic analysis using hierarchical clustering based on chromosomal position displayed a unique pattern of alternating increased and decreased expression of small genetic regions for all chromosomes in this group. These findings may represent long-range genomic regulation that has been attributed to histone modifications and are in keeping with the role of the SWI/SNF chromatin remodeling complex. Analysis using the Affymetrix 6.0 SNP chip demonstrated LOH for 1p31 (ARID1A) and 19p13 (BRG1) in 2 and 1 of the 9 tumors, respectively. Global methylation analysis is underway. Conclusion: Mutations in several SWI/SNF subunits (including ARID1A, BRG1, SMARCB1, PBRM1) have been implicated in the development of a wide range of neoplasias. In normal cells, SWI/SNF subunit protein levels are tightly controlled in a coordinated fashion in order to maintain constant cellular levels. Little is known about the transcriptional regulation of these subunits. This report suggests that a subset of Wilms tumors show striking repression of many SWI/SNF subunits, resulting in a unique globally abnormal gene expression pattern that has not been previously described in tumors with ARID1A or SMARCB1 loss. Whole genomic or exomic sequencing of our tumor set is in progress.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1439. doi:1538-7445.AM2012-1439

Loss of heterozygosity at 2q37 in sporadic Wilms' tumor: putative role for miR-562

PURPOSE

Wilms' tumor is a childhood cancer of the kidney with an incidence of approximately 1 in 10,000. Cooccurrence of Wilms' tumor with 2q37 deletion syndrome, an uncommon constitutional chromosome abnormality, has been reported previously in three children. Given these are independently rare clinical entities, we hypothesized that 2q37 harbors a tumor suppressor gene important in Wilms' tumor pathogenesis.

EXPERIMENTAL DESIGN

To test this, we performed loss of heterozygosity analysis in a panel of 226 sporadic Wilms' tumor samples and mutation analysis of candidate genes.

RESULTS

Loss of heterozygosity was present in at least 4% of cases. Two tumors harbored homozygous deletions at 2q37.1, supporting the presence of a tumor suppressor gene that follows a classic two-hit model. However, no other evidence of second mutations was found, suggesting that heterozygous deletion alone may be sufficient to promote tumorigenesis in concert with other genomic abnormalities. We show that miR-562, a microRNA within the candidate region, is expressed only in kidney and colon and regulates EYA1, a critical gene for renal development. miR-562 expression is reduced in Wilms' tumor and may contribute to tumorigenesis by deregulating EYA1. Two other candidate regions were localized at 2q37.3 and 2qter, but available data from patients with constitutional deletions suggest that these probably do not confer a high risk for Wilms' tumor.

CONCLUSIONS

Our data support the presence of a tumor suppressor gene at 2q37.1 and suggest that, in individuals with constitutional 2q37 deletions, any increased risk for developing Wilms' tumor likely correlates with deletions encompassing 2q37.1.

Molecular characterization of the pediatric preclinical testing panel

PURPOSE

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.

CONCLUSIONS

These data indicate that the preclinical models accurately recapitulate expression profiles and genetic alterations common to childhood cancer, supporting their value in drug development.

Patient weight and event-free survival for children under 2 years of age at diagnosis with favorable histology Wilms tumor

20002

Background: Over- and underweight have been associated with excess mortality in certain childhood cancers. The impact of the child’s weight at diagnosis on event-free survival (EFS) in favorable histology Wilms tumor (FH WT) is unknown. Methods: Patients with FH WT under 2 years of age at enrolment on NWTS-5 were included. This age group was analyzed by body weight in kilograms because body mass index (BMI) norms do not exist for individuals less than 2 years old. Outcomes by BMI for children older than 2 years of age with FH WT will be analyzed separately. CDC 2000 growth charts were used. Patients were stratified for risk based on stage and chemotherapy protocol [EE4A = vincristine/dactinomycin] [DD4A = vincristine/doxorubicin/ actinomycin]. A univariate analysis of the relationship of weight-for-age and EFS was calculated. A Cox proportional hazards model was fitted for EFS examining four subsets of weight-for-age by percentiles: a) less than 5%, b) 5–9.9%, c) 90–94.9% and d) more than 95% and adjusting for risk/treatment groups via stratification. Results: 594 patients met the study criteria. 567 had weights recorded. Median follow-up was 4.7 years. 10% of patients had a weight for age percentile of 5.6 or below and 10% had a weight percentile of 94.1 or above. A univariate analysis of the relationship of weight-for-age and EFS showed no relationship (p=0.40, log-rank test). A Cox proportional hazards model, stratified by risk/treatment groups, showed that low or high weight-for-age was not predictive of outcome (p=0.24). Conclusions: There was no evidence that low or high weight-for-age was predictive for EFS among patients less than 2 years old with FH WT. There were more patients with lower or higher weight than would be expected.

[Table: see text]

No significant financial relationships to disclose.

Rhabdoid tumor of the kidney in the National Wilms' Tumor Study: age at diagnosis as a prognostic factor

PURPOSE

The objective of this study is to determine prognostic factors in rhabdoid tumor of the kidney (RTK), including both demographic and treatment variables.

PATIENTS AND METHODS

A total of 142 patients studied on National Wilms' Tumor Studies 1, 2, 3, 4, and 5 were analyzed. Patients were enrolled between the years 1969 and 2002. Variables examined included sex, age of diagnosis, tumor stage, presence of CNS lesions, as well as treatment variables, including the use of doxorubicin and/or radiotherapy (RT).

RESULTS

No survival differences were observed between males and females, between those treated with or without doxorubicin, or with or without RT. Patients with tumors of lower stage had an overall survival rate of 41.8%, whereas, tumors of higher stage were associated with a 15.9% survival (P < .001). A highly significant difference in survival was noted when patients were stratified according to age of diagnosis. Survival at 4 years in infants under 6 months of age at diagnosis was 8.8%, whereas, survival in patients 2 years of age or older was 41.1% (P < .0001). Stratification into intermediate age brackets demonstrated a strong correlation of increasing survival with increasing age at diagnosis. All patients with a CNS lesion, except one, died.

CONCLUSION

Age at diagnosis is a highly significant prognostic factor for survival of children with RTK. Infants have a dismal prognosis, whereas, older children have a more favorable outcome. Higher tumor stage and presence of a CNS lesion were both factors predictive of a poor survival rate.

Telomerase activity in ductal carcinoma in situ and invasive breast cancer

The increasing number of breast carcinoma in situ detected by screening procedures makes it imperative to develop improved markers to stratify the risk of invasive cancer. Telomerase is detectable in invasive cancer, but not in normal tissues. We have microdissected frozen tissue blocks containing both DCIS and invasive cancer to assay the telomerase activity of these two lesions. The 46 available cases of concurrent DCIS and invasive breast cancer resulted in 43 DCIS samples and 38 invasive cancer samples adequate for analysis. Seventy per cent of the DCIS and all invasive cancer samples tested had detectable telomerase activity. In addition, we analysed telomerase activity in ten cases of DCIS that were not associated with invasive cancer, and detected telomerase activity in seven (70%). Mixing experiments showed no evidence of telomerase inhibitors in telomerase negative samples. Furthermore, periductal inflammatory infiltrates were shown to be a potential confounding source of telomerase activity. Since DCIS lesions appear to be heterogeneous with respect to telomerase activity, and telomerase activation appears to precede the development of invasive cancer, telomerase activity may be a useful adjunct in stratifying the risk of developing invasive breast cancer in patients with DCIS.