Discrete Tumors Research Articles

Role of tumor-specific and whole-body imaging biomarkers for prediction of recurrence in patients with stage III colorectal cancer.

Imaging biomarkers are emerging as non-invasive predictors of cancer prognosis and clinical outcome. We assessed tumor-specific ("radiomics") and body composition imaging features ("morphomics") extracted from baseline pre-treatment CT for prediction of recurrence in patients with stage III colorectal cancer (CRC). Patients with newly diagnosed stage III CRC were enrolled in this prospective observational study. Patients with available preoperative scans were included (N = 101). The tumor, if visible, was manually segmented and first-order radiomics features were extracted with a commercially available software. The morphomics features (reflecting muscle, fat, and bone characteristics) were extracted in a standardized fashion using a proprietary software and the values were adjusted and normalized based on a reference standard. Time to recurrence was the final outcome. Correlation between demographics, clinical features, radiomics, and morphomics features and outcome were assessed using univariate and multivariate tests as well as Kaplan-Meier and log-rank tests. Morphomic analysis was performed in all 101 patients. 60 patients had discrete tumors suitable for radiomics analysis. These patients had lower ECOG score (p < 0.05), more muscle mass (p > 0.05), and lower fat density (p > 0.05) compared to the patients in whom radiomics analysis could not be performed. Pathological stage (HR: 2.69; p = 0.03), CEA level after surgery (HR: 1.11 for 1ng/mL; p < 0.005), bone mineral density (HR: 1.01 for 1 Hounsfield Unit; p < 0.01), and tumor skewness (HR: 0.33 for 1 unit; p < 0.05) had association with recurrence based on both univariate and multivariate analyses. A model using Cox's regression analyses was able to divide the patients into low-, medium-, and high-risk for recurrence. Both radiomics and morphomics features were independently associated with the risk of CRC recurrence and, when combined, each contributed valuable information to explain risk of recurrence. Clinical trial.gov NCT02842203. Patient recruitment occurred between 22/07/2016 and 18/03/2020.

Inducible TgfbR1 and Pten deletion in a model of tongue carcinogenesis and chemoprevention.

Head and neck squamous cell carcinoma (HNSCC) is a significant public health problem, with a need for novel approaches to chemoprevention and treatment. Preclinical models that recapitulate molecular alterations that occur in clinical HNSCC patients are needed to better understand molecular and immune mechanisms of HNSCC carcinogenesis, chemoprevention, and efficacy of treatment. We optimized a mouse model of tongue carcinogenesis with discrete quantifiable tumors via conditional deletion of Tgfβr1 and Pten by intralingual injection of tamoxifen. We characterized the localized immune tumor microenvironment, metastasis, systemic immune responses, associated with tongue tumor development. We further determined the efficacy of tongue cancer chemoprevention using dietary administration of black raspberries (BRB). Three Intralingual injections of 500 µg tamoxifen to transgenic K14 Cre, floxed Tgfbr1, Pten (2cKO) knockout mice resulted in tongue tumors with histological and molecular profiles, and lymph node metastasis similar to clinical HNSCC tumors. Bcl2, Bcl-xl, Egfr, Ki-67, and Mmp9, were significantly upregulated in tongue tumors compared to surrounding epithelial tissue. CD4+ and CD8 + T cells in tumor-draining lymph nodes and tumors displayed increased surface CTLA-4 expression, suggestive of impaired T-cell activation and enhanced regulatory T-cell activity. BRB administration resulted in reduced tumor growth, enhanced T-cell infiltration to the tongue tumor microenvironment and robust antitumoral CD8+ cytotoxic T-cell activity characterized by greater granzyme B and perforin expression. Our results demonstrate that intralingual injection of tamoxifen in Tgfβr1/Pten 2cKO mice results in discrete quantifiable tumors suitable for chemoprevention and therapy of experimental HNSCC.

Surgical Management of Peripheral Nerve Pathology in Patients With Neurofibromatosis Type 2.

Neurofibromatosis type 2 (NF2) is rare genetic disorder mainly characterized by the development of central nervous system lesions, but peripheral nerve pathology may also cause high morbidity including pain, motor, and sensory loss. To describe the tumor burden of patients with peripheral nerve pathology in NF2 including peripheral neuropathies and schwannomas and the results of surgery in the latter group. We conducted a retrospective chart review of all patients with NF2 followed up at our NF2 Reference Center to include all patients suffering from peripheral nerve pathology. Tumor detection relied on focal MRIs based on symptoms. Thirty-four patients harboring 105 peripheral nerve schwannomas and 1 perineurioma were included. Schwannomas were mainly located in major nerves (n = 74, 71%) compared with subcutaneous (n = 23, 22%) and intramuscular (n = 8, 7%) cases. Most schwannomas (81/90-90%) were classical discrete tumors while multinodular cases represented only 9 cases (10%). During follow-up, 63 (60%) tumors were operated in 24 patients, including 39 schwannomas of major nerves. A complete resection was achieved in most of the cases (52/63, 83%) with a complete relief of preoperative pain in most patients (57/60, 95%). Persistent motor deficits (5/39, 13%) were mostly encountered in patients operated from multinodular schwannomas (4/5, 80%). Six patients had an associated peripheral neuropathy with 5 cases of pseudo-Charcot-Marie-Tooth-associated amyotrophy. Surgery remains a safe and effective method of treating peripheral nerve schwannoma-associated pain in NF2, with the exception of rare multinodular tumors. Special attention should be drawn to patients harboring severely debilitating neuropathies and perineuriomas.

3D-Printed Tumor Phantoms for Assessment of In Vivo Fluorescence Imaging Analysis Methods

PurposeInterventional fluorescence imaging is increasingly being utilized to quantify cancer biomarkers in both clinical and preclinical models, yet absolute quantification is complicated by many factors. The use of optical phantoms has been suggested by multiple professional organizations for quantitative performance assessment of fluorescence guidance imaging systems. This concept can be further extended to provide standardized tools to compare and assess image analysis metrics.Procedures3D-printed fluorescence phantoms based on solid tumor models were developed with representative bio-mimicking optical properties. Phantoms were produced with discrete tumors embedded with an NIR fluorophore of fixed concentration and either zero or 3% non-specific fluorophore in the surrounding material. These phantoms were first imaged by two fluorescence imaging systems using two methods of image segmentation, and four assessment metrics were calculated to demonstrate variability in the quantitative assessment of system performance. The same analysis techniques were then applied to one tumor model with decreasing tumor fluorophore concentrations.ResultsThese anatomical phantom models demonstrate the ability to use 3D printing to manufacture anthropomorphic shapes with a wide range of reduced scattering (μs′: 0.24–1.06 mm−1) and absorption (μa: 0.005–0.14 mm−1) properties. The phantom imaging and analysis highlight variability in the measured sensitivity metrics associated with tumor visualization.Conclusions3D printing techniques provide a platform for demonstrating complex biological models that introduce real-world complexities for quantifying fluorescence image data. Controlled iterative development of these phantom designs can be used as a tool to advance the field and provide context for consensus-building beyond performance assessment of fluorescence imaging platforms, and extend support for standardizing how quantitative metrics are extracted from imaging data and reported in literature.

Abstract P5-07-03: Disease classification modeling of inflammatory breast cancer based on simultaneous profiling of coding and non-coding RNAs in tumor and blood samples by TGIRT-sequencing

Abstract Background: Inflammatory breast cancer (IBC) is the most aggressive and lethal breast cancer subtype but lags in disease-specific RNA biomarkers due in part to its paucity of large discrete tumors. A strategy to overcome this challenge is to identify blood-based RNA biomarkers that are minimally invasive and reflect the state of both the diseased breast tissue and the patient's immune response. Here, we identified IBC-specific RNA biomarkers by thermostable group II intron reverse transcriptase sequencing (TGIRT-seq), a recently developed comprehensive RNA-seq technology that enables simultaneous profiling of all RNA biotypes from small amounts of starting material. We used these biomarkers to develop novel disease classification models for IBC based on coding and non-coding RNAs from FFPE tumor slices, PBMCs, and plasma. Methods: We obtained biological samples including FFPE, PBMC, and plasma from a cohort of ten patients with IBC and compared them to samples from six patients with non-IBC and sixteen healthy donors using TGIRT-seq technology. Results: TGIRT-seq of FFPE tumor slices identified differentially expressed mRNAs and miRNAs found previously to distinguish IBC from non-IBC tumors, as well as numerous additional differentially expressed mRNAs and small non-coding RNAs characteristic of IBC. Surprisingly, TGIRT-seq revealed that the differentially expressed protein-coding gene transcripts fall into two categories: mature mRNAs with reads confined to exons, and pre-mRNAs-derived transcripts with reads distributed across exons and introns, to our knowledge, a distinction not made previously for any cancer type. Differentially expressed miRNAs included both mature miRNAs and other transcripts of miRNA loci. IBC PBMCs showed a characteristic inflammatory response not seen in PBMCs from non-IBC patients, as well as differentially expressed tRNAs, snoRNAs, and other sncRNAs, while plasma samples, although of variable quality, included coding and non-coding RNAs distinctive of IBC. Classification models using panels consisting of sets of 50 selected biomarkers profiled by TGIRT-seq achieved a high degree of accuracy under cross-validation, with models based on PBMCs and plasma RNAs correlating with those based on tumor RNAs, and models using both coding and non-coding RNA biomarkers outperforming those based on either alone. Conclusions: Our findings are the first to define a distinct IBC profile across three different tissue types and advance TGIRT-seq as a promising method for high-resolution RNA biomarker profiling of both primary tumors and liquid biopsies with potentially broad utility for diagnosing and defining treatment response in IBC and other cancers. COI: Thermostable group II intron reverse transcriptase (TGIRT) enzymes and methods for their use are the subject of patents and patent applications that have been licensed by the University of Texas to InGex, LLC. A.M.L., some former and present members of the Lambowitz laboratory, and the University of Texas are minority equity holders in InGex, and receive royalty payments from the sale of TGIRT enzymes and kits and from sublicensing of intellectual property to other companies. Citation Format: Dennis C. Wylie, Xiaoping Wang, Jun Yao, Hengyi Xu, Toshiaki Iwase, Savitri Krishnamurthy, Naoto T. Ueno, Alan M. Lambowitz. Disease classification modeling of inflammatory breast cancer based on simultaneous profiling of coding and non-coding RNAs in tumor and blood samples by TGIRT-sequencing [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P5-07-03.

Adult granulosa cell tumor with Mucinous cystadenoma of ovary: a unique case with insight into histogenesis

Mixed ovarian tumors are of common occurrence. In this category are placed rare novelties displaying composite granulosa cell and mucinous tumor elements. Such a combination of stromal and epithelial elements may be a chance association of two discrete tumors. Intriguing still is the intimate admixture of these two elements which has been reported only in two cases till date. (1,2) We report the third such case and review the previous cases with an effort to elucidate their enigmatic histogenesis.

Melanocytic Tumors

Primary melanocytic neoplasms of the central nervous system(CNS)presumably arise from leptomeningeal melanocytes that are derived from the neural crest. Melanocytic neoplasms associated with neurocutaneous melanosis likely derive from melanocyte precursor cells that reach the CNS after somatic mutations, mostly, of the NRAS. They should be distinguished from other melanotic tumors involving the CNS, including metastatic melanoma and other primary tumors that undergo melanization, such as melanocytic schwannomas, medulloblastomas, paragangliomas, and various gliomas, because these lesions require different patient workups and therapy. Primary melanocytic neoplasms of the CNS that are diffuse and do not form macroscopic masses are called melanocytoses, whereas malignant diffuse or multifocal lesions are collectively called melanomatoses. Benign and intermediate-grade tumoral lesions are called melanocytomas. Discrete malignant tumors are called melanomas. CT and MRI of melanocytosis and melanomatosis show diffuse thickening and enhancement of the leptomeninges, often with focal or multifocal nodularity. Depending on the melanin content, diffuse and circumscribed melanocytic tumors of the CNS may show some characteristics on CT and MRI: iso- to hyperattenuation on CT and paramagnetic properties of melanin on MRI resulting in an isointense signal on T1WIs and iso- to hypointensity on T2WIs.

EWSR1(22q12) Translocation Positive Pediatric Adrenal Tumor with Loss of 1p, 11q, and Unbalanced Gain of 17q: Neuroblastoma or Ewing Sarcoma?

Background Although neuroblastoma and Ewing sarcoma/Primitive neuroectodermal tumor are different clinical entities, they are both a member of small round blue cell tumors and can mimic each other’s behavior in clinical and molecular aspects. Case report: A 3 year-old girl with an abdominal mass was found to have a small round blue cell tumor originating from the right adrenal gland. High level of neuron specific enolase, initial genetic test results (N-Myc amplification: negative, loss of 1p, 11q, and unbalanced gain of 17q) and characteristic radiological appearance of the tumor suggested a preliminary diagnosis of neuroblastoma but further analysis showed CD99 expression and presence of EWSR1 rearrangement, which are mostly observed in Ewing sarcoma. Conclusion: Adrenal gland tumors of childhood with complex immunophenotypic features requires distinguishing two discrete tumors in the small round blue cell tumor group, neuroblastoma and Ewing sarcoma. Although no exact diagnosis of the tumor was made, we reached a good response with neuroblastoma treatment protocol.

The role of magnetic resonance imaging in detection and surgical treatment of breast intraductal papillomas

Background: Intraductal papillomas are discrete benign tumors of the breast duct epithelium. Due to the risk of subsequent carcinoma, a surgical excision is generally recommended as a precaution. However, it is difficult to initially diagnose and accurately locate the lesions both in pre-surgery and surgery periods. Methods: Retrospectively analyzed 245 patients, with a pathologically proven breast intraductal papillomas. All the patients underwent magnetic resonance imaging (MRI) scans and ultrasound examination(s) pre-surgery and/or in surgery. All the patients who underwent surgery were divided into four groups according to the following operation method type(s): ultrasound & clinical examination excision, methylene blue notation excision, methylene blue notation & MRI guide excision, and MRI guide excision. Then, the differences between the last two MRI guide excisions and the first two conventional methods were analyzed. Afterwards, 238 patients were followed up for recurrence checks. SPSS 19.0 statistical software was used and the results of P Results: A total of 161 (65.7%) and 48 (19.6%) patients were pathological diagnosed of solitary and multiple papilloma separately, and 36 (14.7%) patients had papillomatosis; 168 and 243 cases with positive signs, which were detected in all 245 patients who had underwent ultrasound and MRI examination(s), with the detection rate being 68.6% and 99.0% respectively. MRI imaging could clearly present mass-like lesions (solitary and multiple mass) and non-mass like lesions (ductal and regional). Whereas, ultrasound imaging could barely show mass-like (solitary and multiple mass) lesions. In surgery, when compared with traditional methods, MRI imaging could also more accurately locate the lesions and guide the excision. MRI guidance is both applicable to patients with and without nipple discharge, in addition to those who show no abnormal signs in ultrasound imaging. The recurrence-free survival time with traditional surgery methods was significantly lower than those in the MRI guide groups. Conclusions: MRI is accurate at the detection, localization and resection range of intraductal papilloma lesions; all capabilities which are critical to successful breast surgery.

The role of magnetic resonance imaging in detection and surgical treatment of breast intraductal papillomas.

BackgroundIntraductal papillomas are discrete benign tumors of the breast duct epithelium. Due to the risk of subsequent carcinoma, a surgical excision is generally recommended as a precaution. However, it is difficult to initially diagnose and accurately locate the lesions both in pre-surgery and surgery periods.MethodsRetrospectively analyzed 245 patients, with a pathologically proven breast intraductal papillomas. All the patients underwent magnetic resonance imaging (MRI) scans and ultrasound examination(s) pre-surgery and/or in surgery. All the patients who underwent surgery were divided into four groups according to the following operation method type(s): ultrasound & clinical examination excision, methylene blue notation excision, methylene blue notation & MRI guide excision, and MRI guide excision. Then, the differences between the last two MRI guide excisions and the first two conventional methods were analyzed. Afterwards, 238 patients were followed up for recurrence checks. SPSS 19.0 statistical software was used and the results of P<0.05 being considered statistically significant.ResultsA total of 161 (65.7%) and 48 (19.6%) patients were pathological diagnosed of solitary and multiple papilloma separately, and 36 (14.7%) patients had papillomatosis; 168 and 243 cases with positive signs, which were detected in all 245 patients who had underwent ultrasound and MRI examination(s), with the detection rate being 68.6% and 99.0% respectively. MRI imaging could clearly present mass-like lesions (solitary and multiple mass) and non-mass like lesions (ductal and regional). Whereas, ultrasound imaging could barely show mass-like (solitary and multiple mass) lesions. In surgery, when compared with traditional methods, MRI imaging could also more accurately locate the lesions and guide the excision. MRI guidance is both applicable to patients with and without nipple discharge, in addition to those who show no abnormal signs in ultrasound imaging. The recurrence-free survival time with traditional surgery methods was significantly lower than those in the MRI guide groups.ConclusionsMRI is accurate at the detection, localization and resection range of intraductal papilloma lesions; all capabilities which are critical to successful breast surgery.

Abstract B47: Modeling epithelial plasticity-induced erlotinib resistance in non-small cell lung cancer

Abstract Background: Advanced non-small lung cancer (NSCLC) patients with EGFR mutations initially respond to treatment with the EGFR-targeted tyrosine kinase inhibitors (TKIs) such as erlotinib, but will invariably acquire resistance with progression of disease within 10–16 months. Mechanisms of EGFR TKIs resistance include second-site EGFR mutations (&amp;gt;50%), MET amplfication (5–10%), and mutations in PIK3CA (&amp;lt;5%). A much less well-defined mechanism of TKIs resistance are lung cancer cells that have appeared to undergone a morphologic change to a more mesenchymal phenotype (~5-30% of cases) or epithelial-mesenchymal transition (EMT). Whether epithelial plasticity programs like EMT are directly causative for erlotinib-acquired resistance has not been shown definitively in vivo. Methods: To examine the relationship between epithelial plasticity and erlotinib resistance in EGFR mutant lung cancers, we created an inducible CCSP-rtTA/tetO-EgfrL858R/Twist1 (CET) transgenic mice (Twist1 is a key regulator of EMT). We utilized the tetracycline-inducible gene expression system to control EgfrL858R/Twist1 gene expression in the lung by providing or withdrawing doxycycline to the mice. The mice were treated for 3 weeks with erlotinib and scanned by CT each week, and survival of the mice was also recorded. The tumor tissues were collected 1 week and 3 weeks after the start of treatment and used for immunohistochemical staining for H&amp;E, Ki67, and cleaved caspase 3 (CC3). To investigate the mechanisms of treatment resistance, mice lung tumor tissues were collected after 3 weeks' treatment with erlotinib, and tumor lysates were used for RTK signaling antibody array analysis. Results: The lung tumors in the CET mice were more anaplastic than those seen in CE (CCSP-rtTA/tetO-EgfrL858R) mice, with larger, more irregular nuclei. This is consistent with reports of cancers expressing Twist1 being more aggressive. Both genotypes display diffuse hyperplasia instead of discrete tumors, which is similar to the disease seen in EGFR mutant NSCLC in humans. After 3 weeks of erlotinib treatment, a majority of CE mice demonstrated complete and partial responses as well as stable disease. Conversely, over half of the CET mice had tumor progression over the three weeks of treatment. CET mice median overall survival time, from the beginning of treatment, was 6.8 weeks, while CE mice lived a median of 8.7 weeks (p&amp;lt;0.01, Mantel–Cox test). When erlotinib-treated tissue was stained for Ki-67, there was no significant difference between proliferation levels in CE and CET mice. Apoptosis assessed through staining for CC3 showed apoptosis levels were decreased in CET erlotinib-treated compared to the CE erlotinib-treated lung tumors. RTK signaling antibody array analysis showed several signaling pathways that were found to be dysregulated between CE and CET lung tumors, with the highest signal observed from the Src kinase pathway. Targeting the Src pathway with 30 mg/kg of dasatinib in combination with erlotinib in CET mice demonstrated significant reduction in tumor burden and increased survival in comparison to the other single-drug groups (p&amp;lt;0.05, Mantel–Cox test). Conclusions: Expression of Twist1 induces resistance to erlotinib in EGFR mutant NSCLC, partially through activation of the Src signaling pathway. Combining erlotinib treatment with the Src inhibitor, dasatinib, in the CET mice leads to tumor regression, prolonged overall survival, as well as decreased proliferation and downstream signaling. Therefore, this combined treatment can potentially overcome Twist1-induced erlotinib resistance in NSCLC. Citation Format: Hailun Wang, Jessica Cades, Zachary Yochum, Katriana Nugent, Charles Rudin, Timothy Burns, Phuoc Tran. Modeling epithelial plasticity-induced erlotinib resistance in non-small cell lung cancer [abstract]. In: Proceedings of the AACR Special Conference: Advances in Modeling Cancer in Mice: Technology, Biology, and Beyond; 2017 Sep 24-27; Orlando, Florida. Philadelphia (PA): AACR; Cancer Res 2018;78(10 Suppl):Abstract nr B47.

English

INTRODUCTION: The giant cell tumor of tendon sheath is among the more common soft tissue tumors of the hand. It is a slowly progressive, usually painless, rubbery mass predominating on the radial three digits of the hand and is typically identified adherent to the digital flexor tendon sheath of the hand. The histology is variable but the tumors consistently contain multinucleated giant cells and xanthoma cells. CASE PRESENTATION: A case report of a 57 years old female patient who came with a diffuse, painless swelling on the radial aspect of middle finger of the right hand at the Orthopedic OPD of our institution. MANAGEMENT & OUTCOME: A planned operative procedure was done. After clinical examination and other investigations, a careful excision of the mass was done by detaching it from the underlying tendon sheath. The tissue was sent for biopsy to two different labs for examination. The reports were confirmed as Giant Cell tumor of the tendon Sheath. DISCUSSION: A giant cell tumors of the tendon sheath (GCTTS) is an uncommon and usually benign lesion that arises from the tendon sheath though they are the second most common tumors of the hand. Recurrence rates are as high. A recent study found that following surgical excision, the only lesions that recurred were those that originally had multiple discrete tumors. Tumors composed of single masses did not recur following surgical excision. MRI may be helpful in determining the anatomic extent of the lesion.

Percutaneous Cryoablation of Extraabdominal Desmoid Tumors: A 10-Year Experience.

Extraabdominal desmoid (EAD) tumors pose a therapeutic challenge because they often recur locally and behave aggressively. Accepted management options include surgery, radiation, chemotherapy, and observation. The objective of this study was to assess the safety and efficacy of percutaneous cryoablation for the treatment of EAD tumors. A retrospective search of our cryoablation database was performed to identify patients with EAD tumors treated with percutaneous cryoablation between June 15, 2004, and June 15, 2014. During this 10-year time period, we treated 18 patients with 26 discrete tumors during 31 treatment sessions. After cryoablation, contrast-enhanced MRI or CT was performed. Any enhancing soft tissue was considered viable EAD tumor and was measured in three planes. Of the 26 EAD tumors treated, follow-up imaging with IV contrast material was available for 23 tumors. The mean imaging follow-up was 16.2 ± 20.0 (SD) months. All 31 sessions were technically successful procedures. No residual viable EAD tumor was observed in nine of 23 tumors (39.1%). Some degree of volume reduction was evident in 22 of 23 tumors (95.7%). Progressive disease was observed in one of the 23 tumors (4.3%). Of the cases with residual or progressive disease, the recurrence occurred at the margin of the treated tumor in all cases. No major complications were observed, and none of the complications was more severe than Clavien-Dindo grade I. Percutaneous cryoablation is a safe, effective, and repeatable treatment for achieving local control of EAD tumors.

Abstract A05: A novel minimal residual disease model of neuroblastoma in mice

Abstract Introduction: Despite aggressive medical and surgical therapy, the 5-year survival rate for high-risk neuroblastoma remains poor at 40-50%. The vast majority of these deaths are not due to the primary tumor but from recurrent metastatic disease. However, current in vivo models of neuroblastoma primarily study the efficacy of novel treatments on primary tumor growth (subcutaneous, orthotopic, transgenic) as opposed to residual metastatic disease as seen in patients. We sought to create an in vivo model of minimal residual disease (MRD), which clinically replicates tumor recurrence and metastasis after surgical resection. Methods: We surgically injected one million luciferase expressing human neuroblastoma cells into the left renal capsule of NSG mice to establish tumor xenografts. The neuroblastoma cell lines CHLA-255 (n=10) and CHLA-136 (n=8) were utilized. At day 14, half of CHLA-255 mice (n=5) and CHLA-136 mice (n=4) underwent complete resection of their primary tumors, while the remaining mice underwent a sham surgery. Extent of disease in mice was monitored weekly by bioluminescent imaging. Mice were sacrificed when they met institutional criteria for euthanasia (weakness/paralysis, seizures, inability to eat or drink, moribund state, dyspnea). Survival data was analyzed using Kaplan-Meier method with significance being determined by log-rank test. P&amp;lt;0.05 was considered significant. Results: In the CHLA-255 group, at the time of sacrifice, 5/5 control mice and 1/5 resection mice were found to have discrete tumors in the left kidney bed. By imaging, 4/5 control mice and 5/5 resected mice were found to have evidence of metastatic disease (femur, liver, brain) at the time of sacrifice. The tumor resection cohort had a mean survival of 47.4 ± 1.3 days compared to 33.8 ± 4.1 days for the non-resection cohort (p=0.003). In the CHLA-136 group, 4/4 control mice and 4/4 resection mice had discrete tumors in the left kidney bed at the time of sacrifice. Imaging demonstrated that 2/4 control mice and 4/4 resected mice were found to have evidence of metastatic disease at the time of sacrifice. The tumor resection cohort had a mean survival of 44 ± 3.2 days compared to 36 ± 2.7 days for the non-resection cohort (p=0.007). Conclusion: In this study, we describe a novel neuroblastoma model of minimal residual disease in mice. Following the resection of an orthotopic xenograft tumor, our in vivo model of MRD demonstrates a 100% rate of metastatic disease in two cell lines of neuroblastoma. This MRD model serves as an innovative means to test novel therapies as well as elucidate the mechanisms in metastatic disease in neuroblastoma. Citation Format: Jeremy R. Jackson, Youngleem Kim, Robert C. Seeger, Eugene S. Kim. A novel minimal residual disease model of neuroblastoma in mice. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Pediatric Cancer Research: From Mechanisms and Models to Treatment and Survivorship; 2015 Nov 9-12; Fort Lauderdale, FL. Philadelphia (PA): AACR; Cancer Res 2016;76(5 Suppl):Abstract nr A05.

Patient-Derived Xenografts (PDX) of B Cell Lymphoma in NSG Mice: A Mouse Avatar for Developing Personalized Medicine

Introduction: In the United States, over 90% of non-Hodgkin's lymphomas (NHL) are derived from mature B lymphocytes. More than 500,000 individuals in the U.S. are living with non-Hodgkin's lymphoma, yet despite an improving 5-year survival rate estimated at 69% for 2014, almost 20,000 deaths were predicted for the year. Personalized medicine for NHL, while still in its infancy, has the potential to improve patient survival and quality of life during treatment. The promise of personalized medicine depends on the ability to guide patient treatment and develop targeted therapies that are specifically tailored to each person's cancer. A key component of this goal is a method to test drug regimens on individual patient samples. To this end, we have developed a new experimental paradigm: mouse Avatars of lymphoma progression using NOD.Cg-PrkdcscidIl2rgtm1Wjl/SzJ (NSG) mice. Defects in both adaptive and innate immunity in NSG mice provide murine hosts receptive for human primary tumors.Results: Here we describe three examples of B cell lymphoma derived from patient samples that were successfully engrafted into NSG mice (the first two specimens were from lymph node biopsies, and the third from bone marrow). Case 1 was derived from follicular lymphoma (FL) Grade 3A with a t(14;18)(q32q21) BCL2-IGH rearrangement. When small tumor specimens were implanted intra-peritoneally (i.p.), discrete tumors formed in recipient mice and dissemination of tumor cells was also observed in spleen and bone marrow. Lymphomas from these mice were subsequently adoptively transferred to 6 secondary recipient NSG host mice to generate widely disseminated tumors, including one mouse with intestinal and pancreatic tumors. Case 2 was diagnosed as diffuse large B cell lymphoma (DLBCL) transformed from pre-existing FL with a t(14;18)(q32q21) BCL2-IGH rearrangement. Fragments of involved lymph node implanted i.p. in NSG mice grew as 0.8-1.4 cm tumors in the abdomen, and tumor cells were also detected in spleen and bone marrow of the mice. Case 3 was a high grade B cell lymphoma (BL) transformed from follicular lymphoma with bone marrow and central nervous system (CNS) involvement. The lymphoma was described as B-cell lymphoma unclassified, with features intermediate between DLBCL and Burkitt's lymphoma. The tumor exhibited a t(8;14) c-myc translocation and a high level of MYC protein expression. A single cell suspension of patient bone marrow was injected intravenously into NSG mice and after 3 months, 6 of 8 recipient mice developed CNS disease with pathology resembling human CNS lymphoma with perivascular and parenchymal invasion. The bone marrow from these mice had nearly 90% lymphoma cells, and high levels of infiltration were also observed in spleen and peritoneal cavity. Transfer of lymphoma cells isolated from CNS of primary recipient mice to secondary mice resulted in lymphoma cells in peripheral blood, spleen, bone marrow, and brain.Conclusions: Altogether, we have successfully developed a new experimental paradigm utilizing mouse Avatars from primary patient B-cell lymphomas. These cases include a spectrum of B-cell lymphoma subtypes including FL, transformed DLBCL, and high grade BL (with MYC translocation). This experimental approach provides a powerful platform for evaluating response to standard and novel therapeutic approaches. This model will also permit investigation of the basis for bone marrow and CNS dissemination of tumor cells in the NSG mouse model, given the clinical importance of B cell lymphoma invasion of these sites. To the best of our knowledge, this is the first demonstration of CNS disease in a B cell lymphoma PDX system. Continued examination of primary, secondary and tertiary grafts and establishment of additional NSG PDX models are ongoing. DisclosuresGerstein:Vertex Pharmaceuticals: Other: employer of spouse. Brehm:The Jackson Laboratory: Consultancy. Cerny:Incyte Inc: Honoraria, Membership on an entity's Board of Directors or advisory committees; Spectrum Inc: Membership on an entity's Board of Directors or advisory committees; Ariad Pharmaceuticals Inc.,: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer Inc: Honoraria, Membership on an entity's Board of Directors or advisory committees. Greiner:The Jackson Laboratory: Honoraria.

Evidence of polyclonality in neurofibromatosis type 2-associated multilobulated vestibular schwannomas.

Neurofibromatosis type 2 (NF2) is a tumor syndrome that results from mutation of the NF2 tumor suppressor gene. The hallmark of NF2 is the presence of bilateral vestibular schwannoma (VS). Though NF2-associated and sporadic VS share identical histopathologic findings and cytogenetic alterations, NF2-associated VS often appears multilobulated, is less responsive to radiosurgery, and has worse surgical outcomes. Temporal bone autopsy specimens and MRI of the inner ear performed on NF2 patients suggest that multiple discrete tumors may be present within the labyrinth and cerebellopontine angle. Treatment-naïve ears in patients enrolled in a prospective NF2 natural history study (NIH#08-N-0044) were included for MRI analysis. T2-weighted and postcontrast T1-weighted MRIs were evaluated for the presence of multiple discrete tumors or a multilobulated mass. Peripheral blood (germline) and regional samples of tumor tissue were procured from consecutive patients enrolled in this study undergoing resection of a multilobulated VS (MVS). Histopathologic evaluation and genetic analysis (single nucleotide polymorphism array analysis, NF2 sequencing) were performed on each specimen. Over half of NF2 ears harbored either an MVS (60/139 ears) or multiple discrete masses (19/139 ears). For 4 successive MVSs, genetic analysis revealed an admixture of cell populations, each with its own somatic NF2 mutation or deletion. These findings suggest that the majority of NF2-associated VSs are polyclonal, such that the tumor mass represents a collision of multiple, distinct tumor clones. This explains the characteristic lobulated gross appearance of NF2-associated VS, and may also explain the substantially different treatment outcomes compared with sporadic VS.

Canine soft tissue sarcoma managed in first opinion practice: outcome in 350 cases.

To determine outcome of dogs with a diagnosis of soft tissue sarcoma managed in first opinion practice. Retrospective, case-controlled study Dogs (n = 350) with primary occurrence of a soft tissue sarcoma. A previously validated questionnaire was sent to all veterinarians requesting clinical information and ultimate outcome for all dogs. Histologic sections were reviewed by a single pathologist. Most surgeries were unplanned, with only 15 (4%) dogs having a histologic and 59 (16.8%) dogs having a cytologic diagnosis before surgery. Median survival time for all dogs was not reached with 70% proportional survival at 5 years. Local recurrence developed in 73 (20.8%) cases. The extent of resection performed was not associated with improved survival (P = .2) or tumor recurrence (P = .8). Age <8 years (χ(2) = 6.1; P = .01), tumors <5 cm in size (χ(2) = 9.6; P = .002) and discrete tumors (χ(2) = 16.6; P < .001) had improved survival outcomes. On multivariate analysis, a high tumor grade was significant for recurrence (HR 5.8; P < .001; 95% CI: 2.2-14.8). Evidence of a selection bias towards less aggressive tumors being managed in first opinion practice was confirmed. Wide resection margins are not the primary determinant of outcome for all soft tissue sarcoma. Veterinarians need to better understand the biologic behavior of a suspected soft tissue sarcoma before treatment to allow surgical margins to be adjusted accordingly.

Expression of MAGE-A restricted to testis and ovary or to various cancers in dogs

Expression of MAGE-A protein, a family of cancer/testis antigens, was investigated in normal and neoplastic canine tissues. Immunohistochemical analysis of cross-reactions between a mouse anti-human MAGE-A proteins including MAGE-A1, -A2, -A3, -A4, -A6, -A10, and -A12 monoclonal antibody and canine proteins, showed positive immunoreactivity only in testicular spermatogonia and spermatocytes, and ovary oocytes. The immunoreaction was negative in all other tissues tested, including normal tissues of the skin, gingiva, muscle, adipose, connective, salivary gland, lymph node, intestinal mucosa, mammary gland, liver, cartilage, oviduct, endometrium, cerebrum and cerebellum. Use of a scoring system in the investigated tumors showed positive immunoreactivity in 75% (21/28) of melanomas including oral, cutaneous, eyelid, and interdigital melanomas; in 68.7% (22/32) of oral and nasal tumors; in 52.5% (21/40) discrete round cell tumors; and in 40.5% (15/37) of soft tissue sarcomas. Different tumor types also showed large difference in percentage of MAGE-A expression. Although oral squamous cell carcinomas, multicentric lymphomas and extraosseous osteosarcomas showed no expression, overexpression occurred in oral melanomas (81.82%, 18/21), malignant nasal tumors (100%, 3/3) and in transmissible venereal tumors (100%, 10/10). Based on the characteristic expression of MAGE-A in canine germ cells and in various neoplasms, MAGE-A has potential use as an indicator of malignancy but is probably unsuitable for strictly diagnostic purposes (i.e., diagnosis of tumor type).

Abstract P2-08-03: Phosphatidylinositol-3-kinase mutations are common in lobular neoplasia

Abstract The phosphatidylinositol-3-kinase pathway is one of the most commonly mutated in invasive breast carcinoma, with PIK3CA mutations present in ∼25% of invasive carcinomas, and several studies demonstrating an even higher prevalence of PIK3CA mutations in invasive lobular carcinomas. Lobular neoplasia (LN), including lobular carcinoma in situ (LCIS) and atypical lobular hyperplasia (ALH), are controversial lesions that may represent non-obligate precursor of invasive lobular carcinoma. However, lobular neoplasia has not yet been systematically studied for activating point mutations. Twenty-six breast resection specimens containing LN and/or invasive lobular carcinoma (ILC) were identified from the files of Oregon Health &amp; Science University. Adjacent lesions including columnar cell change (CCC), usual ductal hyperplasia (UDH), invasive or in-situ ductal carcinoma, and lymph node metastases were separately isolated where available. DNA was prepared from punches of formalin-fixed paraffin-embedded tissue blocks using standard methods. DNA extracts were screened for a panel of point mutations using a multiplex PCR panel with a mass-spectroscopy readout (Sequenom MassArray). The panel covers 643 point mutations in 53 genes including AKT1/2/3, ALK, BRAF, CDK4, CSF1R, CTNNB1, EGFR, ERBB2, ERCC6, FBX4, FBXW7, FES, FGFR1/2/3/4, FOXL2, GNA11, GNAQ, GNAS, HRAS, IDH1/2, IGF1R, KDR, KIT, KRAS, MAPK2K1/2/7, MET, MYC, NEK9, NRAS, NTRK1/2/3, PDGFRA, PIK3CA, PIK3R1/4/5, PKHD1, PRKCB1, RAF1, RET, SMO, SOS1, STAT1, TEC, and TP53; covering 41 substitutions in 23 codons of the PIK3CA gene. PIK3CA mutations were identified in 8/22 LN (36%; PIK3CA exon 4 N345K-1; exon 9 E542K-1; E545K-3; exon 20 H1047R-3), and in 11/16 ILC (68%; PIK3CA exon 4 N345K-2; exon 9 E542K-1, E545K-2, Q546R-1; exon 20 H1047L-1, H1047R-4, one with concomitant HRAS G12D mutation). LN and coincident ILC were tested in 11 patients; 4 patients had the same point mutations in LN and ILC (concordant mutant); 4 patients were wildtype for all codons tested in LN and ILC (concordant wildtype); 3 patients had discordant mutation status (LCIS-E545K/ILC-H1047R; LCIS-E542K/ILC-H1047R; ALH-WT/ILC-H1047R &amp; HRAS G12V). Four patients had LN and invasive ductal carcinoma (IDC); of these, 2 were discordant (LCIS-H1047R/IDC-wildtype; ALH-wildtype/IDC-E545K) and 2 concordant wildtype. Two additional patients had discrete IDC and ILC tumors; in both the IDC was wildtype, but the ILC harbored a PIK3CA mutation. Concurrent CCC and UDH were also screened, yielding 10/22 (45%) lesions with PIK3CA point mutations; in 3 instances the UDH mutation was concordant with LN/ILC, whereas CCC from the same specimen has discordant mutational status. Our study confirms the high prevalence of PIK3CA hotspot point mutations in ILC (68%). Importantly, we screened LCIS and ALH for a large panel of point mutations, and found only PIK3CA mutations (36% of lesions). Although a small cohort, the mutation status of concurrent LN and ILC was frequently concordant (8/11=72%), and in fact, quite similar to the degree of mutational concordance between paired DCIS and IDC in the literature and in our own experience (66–77%). This provides some support to the notion of LN as a precursor to ILC. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P2-08-03.

Multifocal Lipoblastoma of the Face

Lipoblastoma is a rare benign neoplasm found exclusively in the pediatric population that can occur anywhere in the body, most commonly seen in the extremities but also found in the face. We report an 8-month-old female subject who presented with multifocal soft tissue masses of the face. The diagnosis of lipoblastoma was made in 2 separate locations after surgical resection. Subsequent surgery was performed at the cheek site in an attempt to remove further mass, resulting in discovery of 2 other discrete tumors found to be lipoblastomas. Although the literature reports recurrence rates ranging from 14% to 27%, to our knowledge, aside from a case of Proteus syndrome, there are no known reports of multiple lipoblastomas in the literature. Presentation of the case, review of pertinent literature, and consideration of congenital infiltrative lipomatosis of the face follow.