Abstract 1687: Checkpoint inhibitor signatures across endometrial cancer histologies

Background: Therapies targeting immune checkpoints have revolutionized cancer treatment. However, biomarkers that effectively stratify patients to these therapies are required. Endometrial carcinomas consist of several histologies and a subset harbor hypermutation/microsatellite instability (MSI) that has been associated with response to PD-1 inhibition. The purpose of this study was to investigate the immune checkpoint landscape across endometrial cancer subtypes and ascertain whether more complex signatures indicate directions for combination immune therapies in efforts to improve patient response.

Methods: With IRB approval, 60 diagnostic endometrial tumor samples were obtained from 2013-2017 consisting of MSI low grade endometrioid (n=11), microsatellite stable (MSS) low grade endometrioid (n=11), high grade endometrioid (n=16), carcinosarcoma (n=11), and uterine serous carcinoma (n=11) histologies. Immune RNA expression signatures were evaluated using a Luminex platform that evaluated 142 gene targets, including inflammation mediators, immune checkpoints, immune cell type and immune cell polarity markers. Expression of RNA for genes encoding CTLA-4, PD-1, PD-L1, LAG-3, and TIM-3 were quantified and correlated with clinical outcomes utilizing parametric and non-parametric testing. These signatures will be further investigated with multispectral imaging, including proximity analysis.

Results: Cohort characteristics included 32 patients with stage 1A, 9 patients with stage 1B, 6 with stage II, 8 with stage III and 5 with stage IV disease. The median age at diagnosis was 66 years. RNA expression for CTLA-4, PD-1, PD-L1, LAG-3, and TIM-3 were compared across the various endometrial carcinoma histologies. While there were no significant differences noted between carcinosarcoma and serous carcinoma, levels of TIM-3 and CTLA-4 expression were significantly elevated in endometrioid carcinoma (P<0.01, P<0.001 respectively). When evaluating expression within endometrioid subtypes, high grade tumors were independently associated with elevated checkpoint expression (LAG-3 (P=0.04), PD-L1 (P=0.04), and CTLA-4 (P=0.04)), as was the presence of MSI (TIM-3 (P=0.02), PD-L1 (P=0.01), and CTLA-4 (P=0.014). When both grade and MSI were factored together, PD-1 was significantly elevated in MSI high grade versus MSI low grade cancers (P=0.04). RNA expression levels for PD-L1 and PD-L2 were also significantly elevated in endometrioid cancers. Preliminary analysis suggests that recurrent tumors demonstrate altered levels of immune checkpoint signatures compared to those that do not.

Conclusion: A complex landscape of regulatory immune receptors was found across endometrial cancer histologies, with particular relevance in endometrioid carcinomas that was grade and MSI-dependent. These data suggest directions for combined immune blockade therapy in this cancer type.

Citation Format: Amanda Ramos, Sarah Fortin, Victoria Melchert, David Jenkins, Whitfield Growdon, Darrell Borger. Checkpoint inhibitor signatures across endometrial cancer histologies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1687.

Abstract 386: Addition of mTOR inhibition to HER2 blockade results in improved antitumor activity in a preclinical model of uterine serous carcinoma with HER2 gene amplification and a gain of function mutation in PIK3CA

Subsets of uterine serous carcinomas (USC) harbor simultaneous HER2 (ERBB2) over-expression and gain of function mutations in PIK3CA that may play a role in resistance to single agent anti-HER2 therapies. Targeting the mammalian target of rapamycin (mTOR) may be a promising option to heighten anti-tumor response and restore sensitivity to anti-HER2 therapies.

HER2 gene amplified cell lines with (ARK1, E542K) and without (ARK2) PIK3CA gene mutations were divided into four arm cohorts with equivalent tumor volumes and treated with either vehicle, ridaforolimus (1 mg/kg, lapatinib (150 mg/kg) and trastuzumab (10mg/kg) or the combination of lapatinib/trastuzumab and ridaforolimus. At day 22, tumors were collected to measure downstream target proteins and calculate the proliferation and apoptosis index.

In the ARK1 USC xenograft cohort, inhibition of tumor growth was observed following treatment with ridaforolimus compared to vehicle (P<0.05) and this was not statistically different from the lapatinib/trastuzumab group. However, when lapatinib/trastuzumab was combined with ridaforolimus, improved anti-tumor activity was observed compared to all other arms (P<0.01). Similarly, the treatment of ARK2 mice with ridaforolimus slowed tumor growth (P<0.05) compared to the vehicle. Both the lapatinib/trastuzumab and lapatinib/trastuzumab/ridaforolimus arms induced reductions in tumor sizes compared to the vehicle and ridaforolimus arms (P<0.01), but ridaforolimus failed to add any additional anti-tumor activity.

Analysis of the treatment effects revealed the lapatinib/trastuzumab/ridaforolimus therapy was required to decrease Ki67 positive cells in ARK1 xenografts compared to the vehicle (P<0.01) however in ARK2 xenografts, lapatinib/trastuzumab was sufficient to decrease Ki67 positive cells with or without ridaforolimus. Similarly, differential TUNEL staining was observed in the two cell lines with ridaforolimus being required to increase the percentage of apoptotic cells in ARK1, while the apoptotic index was solely dependent of lapatinib/trastuzumab administration in ARK2. In ARK1, we observed that pS6 expression was reduced (p<0.01) only in the arms where ridaforalimus was administered but in ARK2, its expression was again independent of mTOR inhibition.

These data suggest that USCs harboring gain of function PIK3CA mutations are relatively insensitive to anti-HER2 therapies. The addition of downstream mTOR inhibition to HER2 blockade increased the anti-tumor activity only in the xenograft model with PIK3CA mutation and provides rationale for clinical trials in HER2 positive endometrial cancers based on molecular genotype.

Citation Format: Silvia F. Hernandez, Sarah Chisholm, Darrell Borger, Rosemary Foster, Bo R. Rueda, Whitfield B. Growdon. Addition of mTOR inhibition to HER2 blockade results in improved antitumor activity in a preclinical model of uterine serous carcinoma with HER2 gene amplification and a gain of function mutation in PIK3CA. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 386.

Ridaforolimus improves the anti-tumor activity of dual HER2 blockade in uterine serous carcinoma in vivo models with HER2 gene amplification and PIK3CA mutation

OBJECTIVE

Uterine serous carcinomas (USC) harbor simultaneous HER2 (ERBB2) over-expression and gain of function mutations in PIK3CA. These concurrent alterations may uncouple single agent anti-HER2 therapeutic efficacy making inhibition of the mammalian target of rapamycin (mTOR) a promising option to heighten anti-tumor response.

METHODS

Both in vitro and in vivo experiments were conducted to assess proliferation, cell death and anti-tumor activity of ridaforolimus, lapatinib and combination lapatinib, trastuzumab (L/T) and ridaforolimus. With institutional approval, NOD/SCID mice bearing xenografts of non-immortalized, HER2 gene amplified cell lines (ARK1, ARK2) with and without PIK3CA gene mutations were divided into four arm cohorts. Ridaforolimus was administered alone and in combination with L/T. Tumor volumes were assessed and posttreatment analysis was performed.

RESULTS

We observed dose dependent in vitro abrogation of downstream target proteins including phospho-AKT and phospho-S6. In both in vivo models, single agent ridaforolimus impaired xenograft tumor growth. Combination ridaforolimus and L/T, however, further improved the observed anti-tumor activity only in the ARK1 model with the PIK3CA gene mutation (E542K). The addition of mTOR inhibition to dual HER2 blockade added no additional anti-tumor effects in the ARK2 xenografts. Western blot and immunohistochemical analysis of downstream pathway alterations following in vivo treatment revealed dual HER2 blockade with ridaforolimus was necessary to induce apoptosis, decrease proliferation and abrogate phospho-S6 protein expression in the PIK3CA mutated model.

CONCLUSIONS

These pilot data suggest that PIK3CA gene mutation may be an effective biomarker for selecting those HER2 over-expressing USC tumors most likely to benefit from mTOR inhibition.

Abstract 658: Phosphorylated HER3 levels associated with trastuzumab resistance in HER2 gene amplified uterine serous carcinoma xenograft tumors

Uterine serous carcinoma (USC) is an aggressive subtype of endometrial cancer that commonly harbors HER2 gene amplification. Clinical trial has demonstrated that USC is impervious to trastuzumab therapy, though the mechanism is poorly understood. Since HER3 mediated signaling has been implicated in trastuzumab resistance in breast cancer, we sought to understand the relevance of HER3 activation in USC xenografts derived from the HER2 gene amplified (HER2:Chr 17 > 15) non-immortalized USC cell line ARK2. Cohorts of mice harboring xenografts derived from ARK2 were treated with either vehicle, trastuzumab (10 mg/kg IP BIW), lapatinib (150 mg/kg QD oral gavage) or the combination of trastuzumab and lapatinib for 21 days. Acute and chronic post treatment tumor samples were assessed for downstream signaling alterations. Single agent trastuzumab had no impact on xenograft growth compared to vehicle. Lapatinib alone resulted in significant tumorstatic effects (p < 0.01) and dual therapy with trastuzumab and lapatinib induced synergistic activity that significantly decreased tumor volume compared to all other arms (p < 0.01). Single agent trastuzumab was associated with rapid elevation in pHER3 levels with unchanged pAKT and pERK expression compared to vehicle. These elevated pHER3 levels were similarly elevated after the 21 day treatment. Anti-tumor activity observed in the lapatinib and dual lapatinib/trastuzumab arm was not associated with any alterations in pHER3 levels following 21 day treatment, though acute elevations in pHER3 were noted in the dual HER2 blockade arm at 24 hours after treatment. In conclusion, trastuzumab alone failed to impact USC xenograft growth and this innate resistance was associated with an elevation in pHER3 levels that was still evident in xenografts at the end of the treatment period. Unlike single agent trastuzumab, treatment arms that utilized lapatinib demonstrated significant anti-tumor activity with no increase in pHER3 above vehicle over the course of treatment. These data highlight HER3 activation as a possible trastuzumab resistance mechanism in USC that can be abrogated through the addition of lapatinib.

Citation Format: Silvia F. Hernandez, Celeste DiGloria, Jolijn Groeneweg, Darrell Borger, Rosemary Foster, Bo Rueda, Whitfield Growdon. Phosphorylated HER3 levels associated with trastuzumab resistance in HER2 gene amplified uterine serous carcinoma xenograft tumors. [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 658. doi:10.1158/1538-7445.AM2015-658

Abstract 4895: A one-tube assay for simultaneous detection of gene mutation, fusion, copy number alteration and expression

There are growing demands for tumor genotyping in the clinic, with an ever-growing number of mutation/fusion targets and expression profiles needed for tumor diagnostics. We sought to develop a comprehensive yet efficient tumor genetic approach using next-generation sequencing (NGS) that would target the genomic DNA and mRNA components of a sample simultaneously, to decrease costs and labor in the lab, and take advantage of small/limited quantity tumor specimens.

We describe here a novel method termed one-tube anchored multiplex PCR (OneAMP) for combined DNA-and-RNA targeted sequencing, allowing simultaneous detection of gene expression, rearrangements, single nucleotide variations (SNVs), insertion and deletions (Indels) and copy number variation (CNV). In this approach, total nucleic acid is used as input for the assay, starting with cDNA synthesis, shearing, adenylation, and ligation with a half-functional molecule-indexed Y adaptor. The molecular index is a random oligomer and serves as a tag for tracing and counting sample templates from ligation through sequencing. Target enrichment is then achieved by two rounds of hemi-nested PCR using gene specific primers and adaptor primers. Gene specific primers for priming genomic DNA (intronic primer extension to exons for SNVs, Indels and CNV) and for priming cDNA (exonic primer extension for gene fusion and expression) have been optimized so they can be combined in one tube for PCR. A distinctive feature of OneAMP is that mRNA expression is normalized to genomic DNA copy number for the same gene, eliminating the need for normalization to housekeeping genes, which can eliminate significant bias across tissue types and individuals.

We developed a 210 gene OneAMP cancer panel that consists of important cancer genes that are mutated, fused, or with altered expression or copy number. We validated CNV calls with aCGH/FISH of the same samples and validated mRNA expression by comparing to array and qPCR. Finally SNVs, Indels, and fusions were validated with a large panel of samples with known mutation status.

We demonstrate the potential of OneAMP for the comprehensive detection of genetic abnormalities, preserving precious tumor samples, and reducing reagent usage and time.

Citation Format: Zongli Zheng, Ranjit Shetty, Matthew Liebers, Jessica L. Cambry, Lindsay A. Bernardo, Darrell Borger, Long P. Le, John A. Iafrate. A one-tube assay for simultaneous detection of gene mutation, fusion, copy number alteration and expression. [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 4895. doi:10.1158/1538-7445.AM2015-4895

Abstract 2666: PI3K inhibition induces homologous repair defects in endometrioid endometrial cancer patient derived xenografts leading to synergistic anti-tumor activity with PARP inhibitors

Inhibition of the phosphatidylinositol 3-kinase (PI3K) pathway has been shown to induce defective homologous repair in breast carcinoma leading to heightened sensitivity to poly-ADP ribose polymerase (PARP) inhibitors. Our objective was to assess the effects on DNA repair pathways following single agent and combined PI3K and PARP inhibition utilizing endometrial cancer (EnCa) patient derived xenografts (PDX) with and without identified PIK3CA mutations. Under an institutional protocol, tumors from consenting patients with endometrioid carcinoma were collected at the time of primary surgery and genotyped for common oncogenic mutations utilizing the SNaPshot® platform. NOD/SCID mice bearing xenografts derived from two primary human endometrioid endometrial tumors with and without PIK3CA gene mutations (ENCA1 & ENCA2 respectively) were divided into four arm cohorts with equivalent tumor volumes. Vehicle or NVP BKM-120 (30 mg/kg) was administered alone and in combination with veliparib (25 mg/kg) and endometrial xenograft tumor volumes were assessed. Immunoblotting was used to assess downstream PI3K pathway and DNA repair pathway alterations in post treatment samples at specific time points. While NVP BKM120 as a single agent failed to induce significant anti-tumor activity compared to vehicle in either model, decreased pAKT, RAD51 and increased γ-H2AX levels were observed in response to NVP BKM120 alone. PIK3CA mutation status did not affect these molecular alterations. Dual NVP BKM-120 and veliparib therapy significantly impeded tumor growth (p < 0.01) in the ENCA1 model, while in ENCA2, significant tumor regression was observed (p < 0.001). No changes in mouse weight or premature death were observed in the various treatment arms. Combination therapy was associated with reconstitution of baseline RAD51 and increased γ-H2AX levels. In conclusion, these results suggest that PI3K inhibition induces defects in homologous repair mediated by RAD51 and increases reliance on PARP mediated DNA repair mechanisms. Our in vivo data suggest that PI3K inhibition sensitizes endometrial tumors with and without PIK3CA mutations to a PARP inhibitor.

Citation Format: Bo Rueda, Celeste Digloria, Tracilyn Hall, Rosemary Foster, Darrell Borger, Whitfield Growdon. PI3K inhibition induces homologous repair defects in endometrioid endometrial cancer patient derived xenografts leading to synergistic anti-tumor activity with PARP inhibitors. [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 2666. doi:10.1158/1538-7445.AM2015-2666

Abstract P1-13-03: Association of PIK3CA mutation with clinical response to specific endocrine therapies in metastatic hormone receptor positive (HR+) breast cancer

Background: Phosphatidylinositol 3-kinase (PI3K) gene (PIK3CA) mutations are the most common somatic mutations in breast cancer. Preclinical models suggest that activating mutations in PIK3CA may mediate resistance to endocrine therapy in breast cancer, and multiple clinical trials testing combinations of endocrine therapy with PI3K inhibitors are ongoing. However, the role of PIK3CA in modulating the clinical response to endocrine therapies is less clear, with some studies suggesting that PIK3CA mutations are associated with improved prognosis in HR+ breast cancer. The primary objective of this study was to evaluate the association of PIK3CA mutation with clinical response to endocrine therapies in metastatic HR+ breast cancer.

Methods: We identified patients with metastatic HR+ /HER2 negative breast cancer, including ER+/PR+ (estrogen receptor/progesterone receptor) and ER+/PR-, to determine the time to progression (TTP) on first-line endocrine therapy for metastatic disease. PIK3CA mutations, including 8 common hotspot mutations, were assessed by a robust, high-throughput tumor genotyping assay (Snapshot), developed at our institution, using DNA derived from formalin-fixed, paraffin-embedded (FFPE) tissue. Actuarial analysis of TTP was performed using Cox proportional hazard method to compute Hazard Ratio (HR) and 95% Confidence Intervals (CI).

Results: Between 2009 and 2012, we identified 188 patients with HR+ metastatic breast cancer who had tumor genotyping performed. PIK3CA mutations were identified in 32.2% of tumors, including mutations in both helical (exon 9) and kinase (exon 20) domains (60% and 40%, respectively). The PIK3CA mutant and wild type patients had a similar median age at diagnosis of metastatic disease (55.8 and 56.7 years; p=0.2), ER+/PR+ tumors (75.0% vs 76.4%; p=0.8), and median TTP (8.2 versus 11.4 months; p=0.6). After adjusting for age at diagnosis and ER+/PR+ versus ER+/PR-, the TTP on first-line endocrine therapy did not vary among patients with PIK3CA mutations versus wild type (HR: 0.94; 95% CI:0.62-1.43; p=0.8), but did vary by type of endocrine therapy. Patients with PIK3CA mutations, as compared to wild type patients, had shorter TTP with fulvestrant (HR: 3.6; 95% CI:1.2-11.0; p=0.03), but not with aromatase inhibitors (AIs) (HR: 0.70; 95% CI:0.44-1.1; p=0.1), suggesting that mutant PIK3CA may specifically modulate the response to fulvestrant therapy. We did not observe any difference in TTP for exon 9 versus 20 PIK3CA mutations, though numbers were small resulting in limited statistical power.

Conclusion: Among patients with metastatic HR+ breast cancer in this study, PIK3CA mutations are associated with decreased time to progression with fulvestrant, but not with AIs, suggesting that the these mutations may mediate resistance to specific endocrine therapies. Further studies are needed to confirm these findings and provide mechanistic insights to help guide optimal selection of endocrine therapy and combination with PI3K directed therapy in metastatic HR+ breast cancer.

Citation Format: Douglas S Micalizzi, Dejan Juric, Andrzej Niemierko, Kerry L Reynolds, Darrell Borger, Sadhna R Vora, Steven J Isakoff, Beverly Moy, Leif W Ellisen, Aditya Bardia. Association of PIK3CA mutation with clinical response to specific endocrine therapies in metastatic hormone receptor positive (HR+) breast cancer [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P1-13-03.

The Ability to Diagnose Intrahepatic Cholangiocarcinoma Definitively Using Novel Branched DNA-Enhanced Albumin RNA In Situ Hybridization Technology

BACKGROUND

Intrahepatic cholangiocarcinoma (ICC) often is a diagnosis determined by exclusion. Distinguishing ICC from other metastatic adenocarcinomas based on histopathologic or immunohistochemical analysis often is difficult and requires an extensive workup. This study aimed to determine whether albumin, whose expression is restricted to the liver, has potential as a biomarker for ICC using a novel and highly sensitive RNA in situ hybridization (ISH) platform.

METHODS

Modified branched DNA probes were developed for albumin RNA ISH. The study evaluated 467 patient samples of primary and metastatic lesions.

RESULTS

Of the 467 samples evaluated, 83 were ICCs, 42 were hepatocellular carcinomas (HCCs), and 332 were nonhepatic carcinomas including tumors arising from the perihilar region and bile duct, pancreas, stomach, esophagus, colon, breast, ovary, endometrium, kidney, and urinary bladder. Albumin RNA ISH was highly sensitive for cancers of liver origin, staining positive in 82 (99 %) of 83 ICCs and in 42 HCCs (100 %). Perihilar and distal bile duct carcinomas as well as carcinomas arising at other sites tested negative for albumin. Notably, 6 (22 %) of 27 intrahepatic tumors previously diagnosed as carcinomas of undetermined origin tested positive for albumin.

CONCLUSIONS

Albumin RNA ISH is a sensitive and highly specific diagnostic tool for distinguishing ICC from metastatic adenocarcinoma to the liver or carcinoma of unknown origin. Albumin RNA ISH could replace the extensive diagnostic workup, leading to timely confirmation of the ICC diagnosis. Additionally, the assay could serve as a guide to distinguish ICC from perihilar adenocarcinoma.

Clinical Grade "SNaPshot" Genetic Mutation Profiling in Multiple Myeloma

Whole genome sequencing studies have identified several oncogenic mutations in multiple myeloma (MM). As MM progresses, it evolves genetically underscoring the need to have tools for rapid detection of targetable mutations to optimize individualized treatment. Massachusetts General Hospital (MGH) has developed a Clinical Laboratory Improvement Amendments (CLIA)-approved, high-throughput, genotyping platform to determine the mutation status of a panel of known oncogenes. Sequence analysis using SNaPshot on DNA extracted from bone marrow and extramedullary plasmacytomas is feasible and leads to the detection of potentially druggable mutations. Screening MM patients for somatic mutations in oncogenes may provide novel targets leading to additional therapies for this patient population.

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SNaPshot on deoxyribonucleic acid (DNA) extracted from bone marrow and extramedullary plasmacytomas is feasible.

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SNaPshot can detect potentially druggable mutations and thereby integrate rapid genomic analysis into clinical practice.

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SNaPshot can rapidly identify 152 mutations across 15 genes.

Abstract 4260: Standardized decision support in next-generation sequencing (NGS) reports of somatic cancer variants

Introduction: Of hundreds to thousands of somatic mutations that exist in each cancer genome, a large number are unique and non-recurrent variants. Many such variants occur in tumor genes that have well-established biological and clinical relevance and are putative targets of molecular therapy, however, most variants are still of unknown significance. Prioritizing and reporting genetic variants identified via NGS technologies remains a major challenge.

Methods: Based on a systematic framework for cancer variant annotation/prioritization, we propose a structured molecular pathology report using standardized terminology in order to best inform oncology clinical practice. In parallel with the variant interpretation pipeline, we developed a comprehensive knowledge database (Kdb) that integrates tumor types, genes, variants, response/resistance patterns to approved and experimental agents and PubMed identifiers.

Results: As physicians rely heavily on limited subsets of data and frequently apply rules based on strength of evidence in the decision-making process, NGS results are presented in a very discrete manner, avoiding detailed descriptions of each genomic aberration. Reportable variants are grouped in three categories: (i) actionable, which support treatment recommendation, enrollment in clinical trials and/or have prognostic or diagnostic implications; (ii) biologically relevant but not clearly actionable, including novel variants lacking functional preclinical validation in known cancer genes; and (iii) variants of unknown significance. Predictive associations are reported according to tumor type and classified in a hierarchical way based on the strength of evidence: (i) late trials; (ii) early trials; (iii) case reports; and (iv) preclinical data being explored in clinical trials. In our internal Kdb, tumor types with the largest number of emerging predictive associations are acute leukemias, non-small cell lung cancer, brain tumors, melanoma, colorectal, ovarian and breast cancers, comprising more than 100 unique gene - drug interactions. Further interpretation of gene variants requires a team with strong background in cancer biology, careful evaluation of the published literature and ability to match a patient's tumor genotype to clinical trials in the context of multiple aberrations.

Conclusions: With large amounts of data being generated as high throughput sequencing assays enter the clinical realm, there is a growing need to better communicate relevant findings in a timely manner while remaining cognizant of the potential consequences of misuse or overinterpretation of genomic information. The scientific knowledge on actionable events should be presented the report, so that physicians can make evidence-based decisions and patients may benefit from treatment with matched targeted agents. We hope that our experience in this process will help other institutions implement similar programs.

Citation Format: Rodrigo Dienstmann, Fei Dong, Darrell Borger, Dora Dias Santagata, Leif W. Ellisen, Long P. Le, A. John Iafrate. Standardized decision support in next-generation sequencing (NGS) reports of somatic cancer variants. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4260. doi:10.1158/1538-7445.AM2014-4260

Genetic mechanisms in interval colon cancers

BACKGROUND AND AIM

The factors underlying the development of interval colon cancers are not well defined and are likely heterogeneous. We sought to determine whether there are distinct molecular properties associated with interval colon cancers.

METHODS

Colon cancers diagnosed within 5 years of a complete and well-prepped colonoscopic examination were identified over a 7-year period at a single institution. The clinical and pathological features of the tumors were defined. Analysis of DNA mismatch repair (MMR) and genotyping of a panel of oncogenes associated with colon cancer were performed.

RESULTS

Forty-two interval colon cancers were diagnosed at an average age of 70 years. 69 % of tumors were located in the right colon. 41 % of tumors exhibited DNA microsatellite instability (MSI). Loss of staining of DNA MMR proteins by immunohistochemistry (IHC) was confirmed in 82 % of the MSI-positive tumors. Among tumors with abnormal MSI and IHC, 54 % exhibited somatic methylation of the MLH1 promoter, but the remaining 43 % exhibited molecular features indicative of underlying Lynch syndrome (LS). The frequency of somatic mutations in the KRAS, BRAF, NRAS, and PIK3CA oncogenes was similar between interval cancer cases and controls.

CONCLUSIONS

Interval colon cancers are not distinguished by the activation of the KRAS, NRAS, BRAF, or PIK3CA oncogenic pathways. However, MSI pathway defects are present in a significant proportion of interval colon cancers. Underlying LS may explain nearly half of these MSI-positive cases, and the remaining cases appear to represent sporadic serrated pathway tumors.

Standardized decision support in next generation sequencing reports of somatic cancer variants

Of hundreds to thousands of somatic mutations that exist in each cancer genome, a large number are unique and non-recurrent variants. Prioritizing genetic variants identified via next generation sequencing technologies remains a major challenge. Many such variants occur in tumor genes that have well-established biological and clinical relevance and are putative targets of molecular therapy, however, most variants are still of unknown significance. With large amounts of data being generated as high throughput sequencing assays enter the clinical realm, there is a growing need to better communicate relevant findings in a timely manner while remaining cognizant of the potential consequences of misuse or overinterpretation of genomic information. Herein we describe a systematic framework for variant annotation and prioritization, and we propose a structured molecular pathology report using standardized terminology in order to best inform oncology clinical practice. We hope that our experience developing a comprehensive knowledge database of emerging predictive markers matched to targeted therapies will help other institutions implement similar programs.

Assessing the efficacy of targeting the phosphatidylinositol 3-kinase/AKT/mTOR signaling pathway in endometrial cancer

OBJECTIVE

Alterations in the PI3K pathway are prevalent in endometrial cancer due to PIK3CA mutation and loss of PTEN. We investigated the anti-tumor activity of the PI3K inhibitor NVP BKM-120 (BKM) as a single agent and in combination with standard cytotoxic chemotherapy in a human primary endometrial xenograft model.

METHODS

NOD/SCID mice bearing xenografts of primary human tumors with and without PIK3CA gene mutations were divided into two and four arm cohorts with equivalent tumor volumes. BKM was administered alone and in combination with paclitaxel and carboplatin (P/C) and endometrial xenograft tumor volumes were assessed. Tumors from the BKM, P/C, P/C+BKM and vehicle treated mice were processed for determination of PI3K/AKT/mTOR pathway activation.

RESULTS

In both single agent experiments, BKM resulted in significant tumor growth suppression starting at days 5-10 compared to the linear growth observed in vehicle treated tumors (p<0.04 in all experiments). Tumor resurgence manifested between days 14 and 25 (p<0.03). When BKM was combined with P/C, this resistance pattern failed to develop in three separate xenograft lines (p<0.05). Synergistic tumor growth suppression (p<0.05) of only one xenograft tumor with no detected PIK3CA mutation was observed. Acute treatment with BKM led to a decrease in pAKT levels.

CONCLUSION

Independent of PIK3CA gene mutation, BKM mediated inhibition of the PI3K/AKT/mTOR pathway in endometrial tumors precludes tumor growth in a primary xenograft model. While a pattern of resistance emerges, this effect appears to be mitigated by the addition of conventional cytotoxic chemotherapy.

EZH2 codon 641 mutations are common in BCL2-rearranged germinal center B cell lymphomas

Mutations at codon 641 of EZH2 are recurrent in germinal center B cell lymphomas, and the most common variants lead to altered EZH2 enzymatic activity and enhanced tri-methylation of histone H3 at lysine 27, a repressive chromatin modification. As an initial step toward screening patients for cancer genotype-directed therapy, we developed a screening assay for EZH2 codon 641 mutations amenable for testing formalin-fixed clinical specimens, based on the sensitive SNaPshot single nucleotide extension technology. We detected EZH2 mutations in 12/55 (22%) follicular lymphomas (FL), 5/35 (14%) diffuse large B cell lymphomas with a germinal center immunophenotype (GCB-DLBCL), and 2/11 (18%) high grade B cell lymphomas with concurrent rearrangements of BCL2 and MYC. No EZH2 mutations were detected in cases of Burkitt lymphoma (0/23). EZH2 mutations were frequently associated with the presence of BCL2 rearrangement (BCL2-R) in both the FL (28% of BCL-R cases versus 0% of BCL2-WT cases, p<0.05) and GCB-DLBCL groups (33% of BCL2-R cases versus 4% of BCL2-WT cases, p<0.04), and across all lymphoma types excluding BL (27% of BCL2-R cases versus 3% of BCL2-WT cases, p<0.003). We confirmed gain-of-function activity for all previously reported EZH2 codon 641 mutation variants. Our findings suggest that EZH2 mutations constitute an additional genetic "hit" in many BCL2-rearranged germinal center B cell lymphomas. Our work may be helpful in the selection of lymphoma patients for future trials of pharmacologic agents targeting EZH2 and EZH2-regulated pathways.

Energy for living with cancer: preliminary findings of a cancer rehabilitation group intervention study

PURPOSE/OBJECTIVES

To evaluate the acceptability and efficacy of a rehabilitation group intervention for people with cancer experiencing cancer-related fatigue (CRF) and examine the effects of the program on CRF distress. quality of life (QOL), and depression.

DESIGN

Prospective, pre-/post-test intervention.

SETTING

An outpatient area of a 551 -bed tertiary-care community hospital in the southeastern United States.

SAMPLE

20 participants have completed the program in four different groups. The preliminary mean age was 63.6 (range = 38-86). These participants had six different types of cancers, and 15 patients were receiving some form of cancer therapy during their participation in the program.

METHODS

After providing informed consent participants completed the Cancer-Related Fatigue Distress Scale, the Center for Epidemiological Studies-Depression, the Functional Living Index-Cancer, and a demographic Information form. The intervention consists of eight weekly, 90-minute sessions with educational and sharing components. At the eighth session, participants were asked to complete the three instruments plus a program evaluation.

MAIN RESEARCH VARIABLES

CRF distress, depression, QOL.

FINDINGS

Preliminary results indicate that the program provided information, support, and management strategies for CRF. The mean for the program evaluations overall was 9.8 (0-10 scale, range = 9-10). Statistically significant differences were found for pre- and post-test fatigue distress and QOL scores.

CONCLUSIONS

Preliminary findings indicate that this intervention is appropriate and beneficial for patients with cancer experiencing fatigue, even for those patients who are very debilitated.

IMPLICATIONS FOR NURSING PRACTICE

The program can be used as a rehabilitation program to help people with cancer to manage the sequelae of their illness and treatments.

Simultaneous electronic and small format photofluorographic angiography

Monitoring the image on the television screen during photofluorographic angiography is frequently difficult due to the short exposure times. A disk recorder has been integrated with a 100mm rapid-sequence photofluorographic camera for use during selected angiographic procedures. Each flashing image is automatically recorded on the disk recorder and is then immediately replayed during the interval between exposures. It is these considerably longer, although minimally delayed images, that are viewed during the study instead of the short live image. "Panning" to follow the progression of the contrast bolus is facilitated. The recorded angiographic series may be instantly replayed in stop motion for immediate review.