Genetic testing for Lynch syndrome in the province of Ontario.

BACKGROUND: In November 2001, genetic testing for Lynch syndrome (LS) was introduced by the Ministry of Health and Long-Term Care (MOH) in Ontario for individuals at high risk for LS cancers according to either tumor immunohistochemistry staining or their family history. This article describes the outcomes of the program and makes recommendations for improving it and informing other public health care programs. METHODS: Subjects were referred for molecular testing of the mismatch repair (MMR) genes MutL homolog 1, MutS homolog 2, and MutS homolog 6 if they met 1 of 7 MOH criteria. Testing was conducted from January 2001 to March 2015 at the Molecular Diagnostic Laboratory of Mount Sinai Hospital in Toronto. RESULTS: A total of 1452 subjects were tested. Of the 662 subjects referred for testing because their tumor was immunodeficient for 1 or more of the MMR genes, 251 (37.9%) carried a germline mutation. In addition, 597 subjects were tested for a known family mutation, and 298 (49.9%) were positive; 189 of these 298 subjects (63.4%) were affected with cancer at the time of testing. An additional 193 subjects were referred because of a family history of LS, and 34 of these (17.6%) had a mutation identified. CONCLUSIONS: These results indicate that the provincial criteria are useful in identifying LS carriers after an MMR-deficient tumor is identified. Placing greater emphasis on testing unaffected relatives in families with a known mutation may identify more unaffected carriers and facilitate primary prevention in those individuals. Cancer 2016;122:1672-9. © 2016 American Cancer Society.

Central, But Not Peripheral, Circulating Tumor Cells are Prognostic in Patients Undergoing Resection of Colorectal Cancer Liver Metastases.

BACKGROUND: Colorectal cancer liver metastases (CRLMs) are potentially curable with resection, but most patients recur and succumb to their disease. Clinical covariates do not account for all outcomes. Circulating tumor cells (CTCs) are prognostic in the primary and metastatic settings of breast, prostate and colorectal cancer (CRC), and evolving evidence supports their role in CRLMs. Our objective was to determine whether CTCs in peripheral (PV) and hepatic venous (HV) compartments are associated with disease-free survival (DFS) and overall survival (OS) post-CRLM resection. METHODS: CTCs were measured by CellSearch assay from intraoperative HV and PV samples from 63 patients who underwent CRLM resection from June 2007 to August 2012 at a single center. DFS and OS were primary endpoints. RESULTS: HV CTCs > 3 were associated with shorter DFS and OS, but not PV CTCs, although no significant difference was found between CTC measurements in the two compartments. By univariate analysis, CRC stage and site, CRLM recurrence, and hepatic capsule invasion were also associated with OS, but only HV CTCs and CRC site were significant by multivariate Cox. Only HV CTCs were associated with DFS by multivariate analysis. Cases with elevated HV CTCs had hepatic vein invasion and lymph node metastases, and were younger with larger tumors. CONCLUSIONS: Elevated HV CTCs are prognostic for DFS and OS following CRLM resection. Clinicopathologic features associated with HV CTCs are identifiable preoperatively and should be considered in CRLM surgical decision making. We found no evidence that PV CTCs are prognostic in this setting.

Is there a role for prophylactic colectomy in Lynch syndrome patients with inflammatory bowel disease?

PURPOSE: Lynch syndrome and chronic inflammatory bowel disease are two important risk factors for colorectal cancer. It is unclear whether Lynch syndrome patients with inflammatory bowel disease are at sufficiently increased risk for colorectal cancer to warrant prophylactic colectomy. This study aims to identify all cases of Lynch syndrome and concurrent inflammatory bowel disease in a large familial gastrointestinal cancer registry, define incidence of colorectal cancer, and characterize mismatch repair protein gene mutation status and inflammatory bowel disease-associated colorectal cancer risk factors. METHODS: We retrospectively identified and collected clinical data for all cases with confirmed diagnoses of Lynch syndrome and inflammatory bowel disease in the Familial Gastrointestinal Cancer Registry at Mount Sinai Hospital in Toronto, Canada. RESULTS: Twelve cases of confirmed Lynch syndrome, and concurrent inflammatory bowel disease were identified. Four cases developed colorectal cancer. An additional five cases had colectomy; one was performed for severe colitis, and four were performed for low-grade dysplasia. None of these surgical specimens contained malignancy or high-grade dysplasia. CONCLUSIONS: The presentation of Lynch syndrome with inflammatory bowel disease is uncommon and not well described in the literature. This small but important series of twelve cases is the largest reported to date. In this series, patients with Lynch syndrome and concurrent inflammatory bowel disease do not appear to have sufficiently increased risk for colorectal cancer to recommend prophylactic surgery. Therefore, the decision to surgery should continue to be guided by surgical indications for each disease. Further evaluation of this important area will require multi-institutional input.

Bronchial and peripheral murine lung carcinomas induced by T790M-L858R mutant EGFR respond to HKI-272 and rapamycin combination therapy.

The EGFR T790M mutation has been identified in tumors from lung cancer patients that eventually develop resistance to erlotinib. In this study, we generated a mouse model with doxycycline-inducible expression of a mutant EGFR containing both L858R, an erlotinib-sensitizing mutation, and the T790M resistance mutation (EGFR TL). Expression of EGFR TL led to development of peripheral adenocarcinomas with bronchioloalveolar features in alveoli as well as papillary adenocarcinomas in bronchioles. Treatment with an irreversible EGFR tyrosine kinase inhibitor (TKI), HKI-272, shrunk only peripheral tumors but not bronchial tumors. However, the combination of HKI-272 and rapamycin resulted in significant regression of both types of lung tumors. This combination therapy may potentially benefit lung cancer patients with the EGFR T790M mutation.

The impact of human EGFR kinase domain mutations on lung tumorigenesis and in vivo sensitivity to EGFR-targeted therapies.

To understand the role of human epidermal growth factor receptor (hEGFR) kinase domain mutations in lung tumorigenesis and response to EGFR-targeted therapies, we generated bitransgenic mice with inducible expression in type II pneumocytes of two common hEGFR mutants seen in human lung cancer. Both bitransgenic lines developed lung adenocarcinoma after sustained hEGFR mutant expression, confirming their oncogenic potential. Maintenance of these lung tumors was dependent on continued expression of the EGFR mutants. Treatment with small molecule inhibitors (erlotinib or HKI-272) as well as prolonged treatment with a humanized anti-hEGFR antibody (cetuximab) led to dramatic tumor regression. These data suggest that persistent EGFR signaling is required for tumor maintenance in human lung adenocarcinomas expressing EGFR mutants.

Chromosomally unstable mouse tumours have genomic alterations similar to diverse human cancers.

Highly rearranged and mutated cancer genomes present major challenges in the identification of pathogenetic events driving the neoplastic transformation process. Here we engineered lymphoma-prone mice with chromosomal instability to assess the usefulness of mouse models in cancer gene discovery and the extent of cross-species overlap in cancer-associated copy number aberrations. Along with targeted re-sequencing, our comparative oncogenomic studies identified FBXW7 and PTEN to be commonly deleted both in murine lymphomas and in human T-cell acute lymphoblastic leukaemia/lymphoma (T-ALL). The murine cancers acquire widespread recurrent amplifications and deletions targeting loci syntenic to those not only in human T-ALL but also in diverse human haematopoietic, mesenchymal and epithelial tumours. These results indicate that murine and human tumours experience common biological processes driven by orthologous genetic events in their malignant evolution. The highly concordant nature of genomic events encourages the use of genomically unstable murine cancer models in the discovery of biological driver events in the human oncogenome.

LKB1 modulates lung cancer differentiation and metastasis.

Germline mutation in serine/threonine kinase 11 (STK11, also called LKB1) results in Peutz-Jeghers syndrome, characterized by intestinal hamartomas and increased incidence of epithelial cancers. Although uncommon in most sporadic cancers, inactivating somatic mutations of LKB1 have been reported in primary human lung adenocarcinomas and derivative cell lines. Here we used a somatically activatable mutant Kras-driven model of mouse lung cancer to compare the role of Lkb1 to other tumour suppressors in lung cancer. Although Kras mutation cooperated with loss of p53 or Ink4a/Arf (also known as Cdkn2a) in this system, the strongest cooperation was seen with homozygous inactivation of Lkb1. Lkb1-deficient tumours demonstrated shorter latency, an expanded histological spectrum (adeno-, squamous and large-cell carcinoma) and more frequent metastasis compared to tumours lacking p53 or Ink4a/Arf. Pulmonary tumorigenesis was also accelerated by hemizygous inactivation of Lkb1. Consistent with these findings, inactivation of LKB1 was found in 34% and 19% of 144 analysed human lung adenocarcinomas and squamous cell carcinomas, respectively. Expression profiling in human lung cancer cell lines and mouse lung tumours identified a variety of metastasis-promoting genes, such as NEDD9, VEGFC and CD24, as targets of LKB1 repression in lung cancer. These studies establish LKB1 as a critical barrier to pulmonary tumorigenesis, controlling initiation, differentiation and metastasis.

Therapeutic anti-EGFR antibody 806 generates responses in murine de novo EGFR mutant-dependent lung carcinomas.

Activating EGFR mutations occur in human non-small cell lung cancer (NSCLC), with 5% of human lung squamous cell carcinomas having EGFRvIII mutations and approximately 10%-30% of lung adenocarcinomas having EGFR kinase domain mutations. An EGFR-targeting monoclonal antibody, mAb806, recognizes a conformational epitope of WT EGFR as well as the truncated EGFRvIII mutant. To explore the anticancer spectrum of this antibody for EGFR targeted cancer therapy, mAb806 was used to treat genetically engineered mice with lung tumors that were driven by either EGFRvIII or EGFR kinase domain mutations. Our results demonstrate that mAb806 is remarkably effective in blocking EGFRvIII signaling and inducing tumor cell apoptosis, resulting in dramatic tumor regression in the EGFRvIII-driven murine lung cancers. Another EGFR-targeting antibody, cetuximab, failed to show activity in these lung tumors. Furthermore, treatment of murine lung tumors driven by the EGFR kinase domain mutation with mAb806 also induced significant tumor regression, albeit to a less degree than that observed in EGFRvIII-driven tumors. Taken together, these data support the hypothesis that mAb806 may lead to significant advancements in the treatment of the population of NSCLC patients with these 2 classes of EGFR mutations.

Resection of Longitudinal Vaginal Septum Using a Surgical Stapler.

BACKGROUND: A longitudinal vaginal septum is a rare congenital anomaly that can cause dyspareunia, difficulty with tampon insertion, persistent vaginal bleeding, and dysmenorrhea. Various surgical techniques have been described. CASE: We present the case of a 14-year-old girl with obesity and diabetes mellitus with uterine didelphys and double vagina with a longitudinal vaginal septum. The patient presented with dysmenorrhea. Resection of the longitudinal vaginal septum using a GIA and EndoGIA (Medtronic, Inc, Doral Fl) stapler device was performed. SUMMARY AND CONCLUSION: We introduce a safe and effective technique for resecting a longitudinal vaginal septum using stapler technology. This technique eliminates the potential risk of thermal injury to nearby structures from currently described methods.

Regression of drug-resistant lung cancer by the combination of rosiglitazone and carboplatin.

PURPOSE: Current therapy for lung cancer involves multimodality therapies. However, many patients are either refractory to therapy or develop drug resistance. KRAS and epidermal growth factor receptor (EGFR) mutations represent some of the most common mutations in lung cancer, and many studies have shown the importance of these mutations in both carcinogenesis and chemoresistance. Genetically engineered murine models of mutant EGFR and KRAS have been developed that more accurately recapitulate human lung cancer. Recently, using cell-based experiments, we showed that platinum-based drugs and the antidiabetic drug rosiglitazone (PPARgamma ligand) interact synergistically to reduce cancer cell and tumor growth. Here, we directly determined the efficacy of the PPARgamma/carboplatin combination in these more relevant models of drug resistant non-small cell lung cancer. EXPERIMENTAL DESIGN: Tumorigenesis was induced by activation of either mutant KRAS or EGFR. Mice then received either rosiglitazone or carboplatin monotherapy, or a combination of both drugs. Change in tumor burden, pathology, and evidence of apoptosis and cell growth were assessed. RESULTS: Tumor burden remained unchanged or increased in the mice after monotherapy with either rosiglitazone or carboplatin. In striking contrast, we observed significant tumor shrinkage in mice treated with these drugs in combination. Immunohistochemical analyses showed that this synergy was mediated via both increased apoptosis and decreased proliferation. Importantly, this synergy between carboplatin and rosiglitazone did not increase systemic toxicity. CONCLUSIONS: These data show that the PPARgamma ligand/carboplatin combination is a new therapy worthy of clinical investigation in lung cancers, including those cancers that show primary resistance to platinum therapy or acquired resistance to targeted therapy.

Mutations in BRAF and KRAS converge on activation of the mitogen-activated protein kinase pathway in lung cancer mouse models.

Mutations in the BRAF and KRAS genes occur in approximately 1% to 2% and 20% to 30% of non-small-cell lung cancer patients, respectively, suggesting that the mitogen-activated protein kinase (MAPK) pathway is preferentially activated in lung cancers. Here, we show that lung-specific expression of the BRAF V600E mutant induces the activation of extracellular signal-regulated kinase (ERK)-1/2 (MAPK) pathway and the development of lung adenocarcinoma with bronchioloalveolar carcinoma features in vivo. Deinduction of transgene expression led to dramatic tumor regression, paralleled by dramatic dephosphorylation of ERK1/2, implying a dependency of BRAF-mutant lung tumors on the MAPK pathway. Accordingly, in vivo pharmacologic inhibition of MAPK/ERK kinase (MEK; MAPKK) using a specific MEK inhibitor, CI-1040, induced tumor regression associated with inhibition of cell proliferation and induction of apoptosis in these de novo lung tumors. CI-1040 treatment also led to dramatic tumor shrinkage in murine lung tumors driven by a mutant KRas allele. Thus, somatic mutations in different signaling intermediates of the same pathway induce exquisite dependency on a shared downstream effector. These results unveil a potential common vulnerability of BRAF and KRas mutant lung tumors that potentially affects rational deployment of MEK targeted therapies to non-small-cell lung cancer patients.

Telomere dysfunction promotes genome instability and metastatic potential in a K-ras p53 mouse model of lung cancer.

Current mouse models of lung cancer recapitulate signature genetic lesions and some phenotypic features of human lung cancer. However, because mice have long telomeres, models to date do not recapitulate the aspects of lung carcinogenesis-telomere attrition and the genomic instability that ensues-believed to serve as key mechanisms driving lung tumor initiation and progression. To explore the contributions of telomere dysfunction to lung cancer progression, we combined a telomerase catalytic subunit (mTerc) mutation with the well-characterized K-rasG12D mouse lung cancer model. K-ras(G12D) mTerc(-/-) mice with telomere dysfunction but intact p53 exhibited increased lung epithelial apoptosis, delayed tumor formation and increased life span relative to K-ras(G12D) mTerc(+/-) mice with intact telomere function. This demonstrates that by itself, telomere dysfunction acts in a tumor-suppressive mechanism. Introduction of a heterozygous p53 mutation exerted a marked histopathological, biological and genomic impact. K-ras(G12D) mTerc(-/-) p53(+/-) mice developed aggressive tumors with more chromosomal instabilities and high metastatic potential, leading to decreased overall survival. Thus, we have generated a murine model that more faithfully recapitulates key aspects of the human disease. Furthermore, these findings clearly demonstrate (in an in vivo model system) the dual nature of telomere shortening as both a tumor-suppressive and tumor-promoting mechanism in lung cancer, dependent on p53 status.

Telomere shortening and mood disorders: preliminary support for a chronic stress model of accelerated aging.

BACKGROUND: Little is known about the biological mechanisms underlying the excess medical morbidity and mortality associated with mood disorders. Substantial evidence supports abnormalities in stress-related biological systems in depression. Accelerated telomere shortening may reflect stress-related oxidative damage to cells and accelerated aging, and severe psychosocial stress has been linked to telomere shortening. We propose that chronic stress associated with mood disorders may contribute to excess vulnerability for diseases of aging such as cardiovascular disease and possibly some cancers through accelerated organismal aging. METHODS: Telomere length was measured by Southern Analysis in 44 individuals with chronic mood disorders and 44 nonpsychiatrically ill age-matched control subjects. RESULTS: Telomere length was significantly shorter in those with mood disorders, representing as much as 10 years of accelerated aging. CONCLUSIONS: These results provide preliminary evidence that mood disorders are associated with accelerated aging and may suggest a novel mechanism for mood disorder-associated morbidity and mortality.

Back to basics--cutting the cord on umbilical infections.

INTRODUCTION: Surgical site infections (SSIs) are a significant cause of postoperative morbidity with laparoscopic surgery associated with lower SSI rates. However, a departmental change in our unit to increased laparoscopic colorectal surgery resulted in increased wound infection rates at umbilical specimen extraction sites, the cause of which we attempted to elucidate. SUBJECTS AND METHODS: Prospectively collected data over an 18-month period (April 2008 to September 2009) for laparoscopic colorectal operations in a busy teaching hospital were retrospectively analysed, focusing on operation performed, whether pre-operative skin cleansing was employed, nature of specimen extraction excision, and rate of umbilical wound infection. Comparison was made with open colorectal procedures performed in the preceding year. RESULTS: In total, 275 laparoscopic colorectal operations were performed. Over the first 8 months there was a significant increase in infection rates when compared with open procedures over a similar time period (23.5% vs 8.0%; P = 0.0001). Changing practice to use pre-operative skin cleansing and an incision that skirted around, as opposed to traversing, the umbilicus reduced umbilical infection rates significantly from 23.5% to 11.6% (P = 0.01). Patients undergoing right hemicolectomy benefitted more (reduction of 30.0% to 6.9%; P = 0.04) than those undergoing anterior resection (26.8% vs 15.6%, P = 0.13). CONCLUSIONS: Umbilical incisions, when extended for specimen extraction, are particularly prone to infection following colorectal surgery but rates can be reduced by simple measures such as pre-operative umbilical cleansing and avoidance of the umbilicus in the incision, without the need for drastic and costly changes in technique or antibiotic prophylaxis.

A rare case of a concurrent large thyroglossal duct cyst with a base of tongue haemangioma.

An 85-year-old lady presented with a large midline neck mass. After 8 years of steady growth, the previously asymptomatic mass began to cause stridor and dysphagia. The patient's comorbidities included a previous partial glossectomy for haemangioma of the tongue, chronic obstructive pulmonary disease, congestive cardiac failure and obesity (body mass index >30). CT neck revealed the midline mass was cystic in nature, most likely a thyroglossal duct cyst. This mass was closely related to an angiomatous malformation involving the tongue, floor of mouth and left parotid. Fine needle aspiration cytology was consistent with a colloid goitre characterised as Thy-1. Due to her extensive comorbidities, surgical resection of the midline mass was deemed to be a high-risk procedure. A Sistrunk's procedure was performed. Dissection proved difficult due to the intimately related base of tongue haemangioma. Histopathology confirmed it to be a benign thyroglossal duct cyst. She made an uncomplicated postoperative recovery.

Integrative genomic and proteomic analyses identify targets for Lkb1-deficient metastatic lung tumors.

In mice, Lkb1 deletion and activation of Kras(G12D) results in lung tumors with a high penetrance of lymph node and distant metastases. We analyzed these primary and metastatic de novo lung cancers with integrated genomic and proteomic profiles, and have identified gene and phosphoprotein signatures associated with Lkb1 loss and progression to invasive and metastatic lung tumors. These studies revealed that SRC is activated in Lkb1-deficient primary and metastatic lung tumors, and that the combined inhibition of SRC, PI3K, and MEK1/2 resulted in synergistic tumor regression. These studies demonstrate that integrated genomic and proteomic analyses can be used to identify signaling pathways that may be targeted for treatment.

Sunitinib prolongs survival in genetically engineered mouse models of multistep lung carcinogenesis.

Non-small cell lung cancer (NSCLC) has a poor prognosis, with substantial mortality rates even among patients diagnosed with early-stage disease. There are few effective measures to block the development or progression of NSCLC. Antiangiogenic drugs represent a new class of agents targeting multiple aspects of tumor progression, including cell proliferation, invasion, migration, and outgrowth of metastatic deposits. We tested the multitargeted angiogenesis inhibitor sunitinib in a novel endogenous mouse model of NSCLC, which expresses a conditional activating mutation in Kras with or without conditional deletion of Lkb1; both alterations are frequent in human NSCLC. We showed that daily treatment with sunitinib reduced tumor size, caused tumor necrosis, blocked tumor progression, and prolonged median survival in both the metastatic (Lkb1/Kras) and nonmetastatic (Kras) mouse models; median survival was not reached in the nonmetastatic model after 1 year. However, the incidence of local and distant metastases was similar in sunitinib-treated and untreated Lkb1/Kras mice, suggesting that prolonged survival with sunitinib in these mice was due to direct effects on primary tumor growth rather than to inhibition of metastatic progression. These collective results suggest that the use of angiogenesis inhibitors in early-stage disease for prevention of tumor development and growth may have major survival benefits in the setting of NSCLC.

Effective use of PI3K and MEK inhibitors to treat mutant Kras G12D and PIK3CA H1047R murine lung cancers.

Somatic mutations that activate phosphoinositide 3-kinase (PI3K) have been identified in the p110-alpha catalytic subunit (encoded by PIK3CA). They are most frequently observed in two hotspots: the helical domain (E545K and E542K) and the kinase domain (H1047R). Although the p110-alpha mutants are transforming in vitro, their oncogenic potential has not been assessed in genetically engineered mouse models. Furthermore, clinical trials with PI3K inhibitors have recently been initiated, and it is unknown if their efficacy will be restricted to specific, genetically defined malignancies. In this study, we engineered a mouse model of lung adenocarcinomas initiated and maintained by expression of p110-alpha H1047R. Treatment of these tumors with NVP-BEZ235, a dual pan-PI3K and mammalian target of rapamycin (mTOR) inhibitor in clinical development, led to marked tumor regression as shown by positron emission tomography-computed tomography, magnetic resonance imaging and microscopic examination. In contrast, mouse lung cancers driven by mutant Kras did not substantially respond to single-agent NVP-BEZ235. However, when NVP-BEZ235 was combined with a mitogen-activated protein kinase kinase (MEK) inhibitor, ARRY-142886, there was marked synergy in shrinking these Kras-mutant cancers. These in vivo studies suggest that inhibitors of the PI3K-mTOR pathway may be active in cancers with PIK3CA mutations and, when combined with MEK inhibitors, may effectively treat KRAS mutated lung cancers.

Hsp90 inhibition suppresses mutant EGFR-T790M signaling and overcomes kinase inhibitor resistance.

The epidermal growth factor receptor (EGFR) secondary kinase domain T790M non-small cell lung cancer (NSCLC) mutation enhances receptor catalytic activity and confers resistance to the reversible tyrosine kinase inhibitors gefitinib and erlotinib. Currently, irreversible inhibitors represent the primary approach in clinical use to circumvent resistance. We show that higher concentrations of the irreversible EGFR inhibitor CL-387,785 are required to inhibit EGFR phosphorylation in T790M-expressing cells compared with EGFR mutant NSCLC cells without T790M. Additionally, CL-387,785 does not fully suppress phosphorylation of other activated receptor tyrosine kinases (RTK) in T790M-expressing cells. These deficiencies result in residual Akt and mammalian target of rapamycin (mTOR) activities. Full suppression of EGFR-mediated signaling in T790M-expressing cells requires the combination of CL-387,785 and rapamycin. In contrast, Hsp90 inhibition overcomes these limitations in vitro and depletes cells of EGFR, other RTKs, and phospho-Akt and inhibits mTOR signaling whether or not T790M is present. EGFR-T790M-expressing cells rendered resistant to CL-387,785 by a kinase switch mechanism retain sensitivity to Hsp90 inhibition. Finally, Hsp90 inhibition causes regression in murine lung adenocarcinomas driven by mutant EGFR (L858R) with or without T790M. However, efficacy in the L858R-T790M model requires a more intense treatment schedule and responses were transient. Nonetheless, these findings suggest that Hsp90 inhibitors may be effective in T790M-expressing cells and offer an alternative therapeutic strategy for this subset of lung cancers.