Pathologist-trained machine learning classifiers developed to quantitate celiac disease features differentiate endoscopic biopsies according to modified marsh score and dietary intervention response

BACKGROUND

Histologic evaluation of the mucosal changes associated with celiac disease is important for establishing an accurate diagnosis and monitoring the impact of investigational therapies. While the Marsh-Oberhuber classification has been used to categorize the histologic findings into discrete stages (i.e., Type 0-3c), significant variability has been documented between observers using this ordinal scoring system. Therefore, we evaluated whether pathologist-trained machine learning classifiers can be developed to objectively quantitate the pathological changes of villus blunting, intraepithelial lymphocytosis, and crypt hyperplasia in small intestine endoscopic biopsies.

METHODS

A convolutional neural network (CNN) was trained and combined with a secondary algorithm to quantitate intraepithelial lymphocytes (IEL) with 5 classes on CD3 immunohistochemistry whole slide images (WSI) and used to correlate feature outputs with ground truth modified Marsh scores in a total of 116 small intestine biopsies.

RESULTS

Across all samples, median %CD3 counts (positive cells/enterocytes) from villous epithelium (VE) increased with higher Marsh scores (Type 0%CD3 VE = 13.4; Type 1-3%CD3 VE = 41.9, p < 0.0001). Indicators of villus blunting and crypt hyperplasia were also observed (Type 0-2 villous epithelium/lamina propria area ratio = 0.81; Type 3a-3c villous epithelium/lamina propria area ratio = 0.29, p < 0.0001), and Type 0-1 crypt/villous epithelial area ratio = 0.59; Type 2-3 crypt/villous epithelial area ratio = 1.64, p < 0.0001). Using these individual features, a combined feature machine learning score (MLS) was created to evaluate a set of 28 matched pre- and post-intervention biopsies captured before and after dietary gluten restriction. The disposition of the continuous MLS paired biopsy result aligned with the Marsh score in 96.4% (27/28) of the cohort.

CONCLUSIONS

Machine learning classifiers can be developed to objectively quantify histologic features and capture additional data not achievable with manual scoring. Such approaches should be further investigated to improve biopsy evaluation, especially for clinical trials.

A Phase 2 study of prexasertib (LY2606368) in platinum resistant or refractory recurrent ovarian cancer

OBJECTIVE

High-grade serous ovarian cancer, the most frequent type of ovarian cancer, has a poor prognosis and novel treatments are needed for patients with platinum resistant/refractory disease. New therapeutic strategies targeting cell cycle checkpoints, including CHK1 inhibition with prexasertib, may help improve clinical response and overcome resistance.

METHODS

Patients with ovarian cancer (N = 169) were assigned to 4 cohorts as part of the Phase 2 multicenter trial (NCT03414047): Cohort 1: platinum resistant, BRCA-wildtype with ≥3 lines prior therapy; Cohort 2: platinum resistant BRCA-wildtype with <3 lines prior therapy; Cohort 3: platinum resistant, BRCA-mutated with prior PARP inhibitor therapy; Cohort 4: platinum refractory, BRCA-mutated, or BRCA-wildtype with any number of prior therapy lines. The primary endpoint was objective response rate (ORR) and secondary endpoints included disease control rate (DCR), and safety. DNA from tumor biopsies was sequenced to identify biomarkers.

RESULTS

The ORR in platinum resistant patients (Cohorts 1--3) was 12.1%, and 6.9% in platinum refractory patients. In platinum resistant patients, DCR was 37.1%, and consistent across cohorts. In platinum refractory patients, DCR was 31.0%. Consistent with the prexasertib mechanism of action, the most common treatment related adverse events of all grades included thrombocytopenia, neutropenia, fatigue, nausea, and anemia.

CONCLUSIONS

Prexasertib demonstrated durable single agent activity in a subset of patients with recurrent ovarian cancer regardless of clinical characteristics, BRCA status, or prior therapies, including PARPi. There was no obvious correlation with genomic alterations in responders vs non-responders, emphasizing the need for alternative biomarker approaches for responder identification.

Effects of 0.5% and 2.0% Sodium Lauryl Sulfate in Male CD-1 Mice From a 3-Month Oral Gavage Toxicity Study

The tolerability of single daily gavage doses of 0.5% or 2.0% (wt/vol) sodium lauryl sulfate (SLS) in 11- to 12-week-old male CD-1 mice was evaluated in a study of 3 months in duration. Live-phase, gross necropsy, and histopathologic parameters were evaluated. Mortality of 14% occurred in mice administered formulations containing SLS. Clinical observations in mice administered SLS included abnormal respiration (audible, irregular, and/or labored), swollen abdomen, rough haircoat, hunched appearance, and hypoactivity. Necropsy findings in mice administered SLS consisted of enlarged intestines containing abnormal contents with gas. There were no instances of mechanical gavage-related injury. Histologic evaluation of the respiratory tract revealed injury to the nasal passages and nasopharynx, including, but not limited to, inflammation, exudate, apoptosis/necrosis of epithelium, and atrophy of epithelium or olfactory nerves. Collectively, the data indicated that under the experimental conditions of our 3-month study in male CD-1 mice, once-daily gavage administration of vehicle formulations containing SLS at 0.5% or 2.0% resulted in nasal injury and 14% mortality supportive of gastroesophageal reflux. Sponsors utilizing formulations containing SLS in toxicity studies in CD-1 mice should exclude gastroesophageal reflux as a confounding factor in studies with morbidity or mortality associated with respiratory distress or evidence of aerophagia.

Inhibition of myostatin prevents microgravity-induced loss of skeletal muscle mass and strength

The microgravity conditions of prolonged spaceflight are known to result in skeletal muscle atrophy that leads to diminished functional performance. To assess if inhibition of the growth factor myostatin has potential to reverse these effects, mice were treated with a myostatin antibody while housed on the International Space Station. Grip strength of ground control mice increased 3.1% compared to baseline values over the 6 weeks of the study, whereas grip strength measured for the first time in space showed flight animals to be -7.8% decreased in strength compared to baseline values. Control mice in space exhibited, compared to ground-based controls, a smaller increase in DEXA-measured muscle mass (+3.9% vs +5.6% respectively) although the difference was not significant. All individual flight limb muscles analyzed (except for the EDL) weighed significantly less than their ground counterparts at the study end (range -4.4% to -28.4%). Treatment with myostatin antibody YN41 was able to prevent many of these space-induced muscle changes. YN41 was able to block the reduction in muscle grip strength caused by spaceflight and was able to significantly increase the weight of all muscles of flight mice (apart from the EDL). Muscles of YN41-treated flight mice weighed as much as muscles from Ground IgG mice, with the exception of the soleus, demonstrating the ability to prevent spaceflight-induced atrophy. Muscle gene expression analysis demonstrated significant effects of microgravity and myostatin inhibition on many genes. Gamt and Actc1 gene expression was modulated by microgravity and YN41 in opposing directions. Myostatin inhibition did not overcome the significant reduction of microgravity on femoral BMD nor did it increase femoral or vertebral BMD in ground control mice. In summary, myostatin inhibition may be an effective countermeasure to detrimental consequences of skeletal muscle under microgravity conditions.

Merestinib (LY2801653) inhibits neurotrophic receptor kinase (NTRK) and suppresses growth of NTRK fusion bearing tumors

Merestinib is an oral multi-kinase inhibitor targeting a limited number of oncokinases including MET, AXL, RON and MKNK1/2. Here, we report that merestinib inhibits neurotrophic receptor tyrosine kinases NTRK1/2/3 which are oncogenic drivers in tumors bearing NTRK fusion resulting from chromosomal rearrangements. Merestinib is shown to be a type II NTRK1 kinase inhibitor as determined by x-ray crystallography. In KM-12 cells harboring TPM3-NTRK1 fusion, merestinib exhibits potent p-NTRK1 inhibition in vitro by western blot and elicits an anti-proliferative response in two- and three-dimensional growth. Merestinib treatment demonstrated profound tumor growth inhibition in in vivo cancer models harboring either a TPM3-NTRK1 or an ETV6-NTRK3 gene fusion. To recapitulate resistance observed from type I NTRK kinase inhibitors entrectinib and larotrectinib, we generated NIH-3T3 cells exogenously expressing TPM3-NTRK1 wild-type, or acquired mutations G595R and G667C in vitro and in vivo. Merestinib blocks tumor growth of both wild-type and mutant G667C TPM3-NTRK1 expressing NIH-3T3 cell-derived tumors. These preclinical data support the clinical evaluation of merestinib, a type II NTRK kinase inhibitor (NCT02920996), both in treatment naïve patients and in patients progressed on type I NTRK kinase inhibitors with acquired secondary G667C mutation in NTRK fusion bearing tumors.

Abstract 5590: Combination of an oncokinase inhibitor merestinib with anti-PD-L1 results in enhanced immune mediated antitumor activity in CT26 murine tumor model

The combination of tumor targeted therapeutics with PD-L1 checkpoint blockade is being explored as a method to increase the clinical benefits of immunotherapy, and expand response to additional cancer types. Merestinib (Mer) is a kinase inhibitor targeting several oncokinases1 (including MET, MST1R, AXL, MERTK, and MKNK1/2) that can potentially modulate immune function, angiogenesis, as well as target the tumor 1-5. To determine the combinatorial potential with immunotherapy, the effects of Mer were evaluated in vitro on human T cells, PBMCs and murine tumor lines CT26 colon carcinoma (harbors KRASmt G12D expresses low Met/no p-Met/high Axl/p-Axl) and B16F10 melanoma (expressing high Met/pMet/peIF4E). Additionally, the anti-tumor effect of Mer was tested in vivo on established CT26 and B16F10 tumors compared to MET specific TKIs (savolitinib, PF4217903) alone or in combination with PD-L1 antibody (Ab) blockade. In vitro, Mer showed no significant effects on either T cells or PBMCs, but was able to inhibit downstream signaling in both CT26 and B16F10 showing activity on murine tumor cell lines. In vivo, daily Mer monotherapy (6, 12 or 24 mg/kg) showed significant anti-tumor effect at all doses in both CT26 and B16F10, that was not seen with either savolitinib or PF4217903. Concurrent combination of Mer (12 mg/kg) and anti-PD-L1 Ab (0.5 mg qw) in CT26 was found to have anti-tumor activity that was synergistic as compared to each single agent alone. While the effect of Mer monotherapy was lost when treatment ended, tumors continued to regress in the combination group even upon cessation of therapy. The combination was well tolerated and resulted in 90% complete responders compared to 30% with anti-PD-L1 Ab alone, 35 days after completing dosing. To test the ability to generate immunologic memory, complete responders were re-challenged with CT26 cells on the contralateral side. All mice in the combination group resisted re-challenge, showing that Mer/PD-L1 Ab combination was triggering immunologic memory. Although there was no significant change in intra-tumor immune cell populations between groups, combination therapy showed an enhanced and unique intra-tumor immune activation/inflammation gene expression signature compared to PD-L1 Ab monotherapy. The enhanced immune activation of the combination therapy, leading to synergistic anti-tumor efficacy, demonstrates that merestinib has the potential to augment immunotherapy while targeting the tumor directly. This preclinical data provides the rationale for the clinical investigation of merestinib in combination with checkpoint therapies targeting the PD-L1/PD1 axis (NCT02791334). 1 - Yan et al. Invest New Drugs 2013;31:833-44 2 - Balan et al. J Biol Chem 2015;290:8110-20 3 - Eyob et al. Cancer Discov 2013;3:751-60 4 - Lemke G. CSH Persp Biol 2013;5:a009076 5 - Piccirillo et al. Nat Immunol 2014;15:503-11

Citation Format: Sau-Chi Betty Yan, Victoria L. Peek, Jennifer R. Stephens, Um L. Um, Amaladas Nelusha, Colleen A. Burns, Kelly M. Credille, Thompson N. Doman, Scott W. Eastman, Beverly L. Falcon, Gerald E. Hall, Philip W. Iversen, Bruce W. Konicek, Jason R. Manro, Any T. Pappas, Julie A. Stewart, Michael B. Topper, Swee-Seong Wong, Michael Kalos, Ruslan D. Novosiadly, Richard A. Walgren, David Schaer. Combination of an oncokinase inhibitor merestinib with anti-PD-L1 results in enhanced immune mediated antitumor activity in CT26 murine tumor model [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5590. doi:10.1158/1538-7445.AM2017-5590

Variability in Platelet-Derived Growth Factor Receptor Alpha Antibody Specificity May Impact Clinical Utility of Immunohistochemistry Assays

Aberrant regulation of the receptor tyrosine kinase platelet-derived growth factor alpha (PDGFRα) is implicated in several types of cancer. Inhibition of the PDGFRα pathway may be a beneficial therapy, and detection of PDGFRα in tumor biopsies may lead to insights about which patients respond to therapy. Exploratory or clinical biomarker use of PDGFRα IHC has been frequently reported, often with polyclonal antibody sc-338. An sc-338-based assay was systematically compared with anti-PDGFRα rabbit monoclonal antibody D13C6 using immunoblot profiling and IHC in formalin-fixed and paraffin-embedded human tumor cell lines. Application of sc-338 to blots of whole cell lysates showed multiple bands including some of unknown origin, whereas application of D13C6 resulted in a prominent band at the expected molecular mass of PDGFRα. The IHC assay using D13C6 showed appropriate staining in cell lines, whereas the assay using sc-338 suggested nonspecific detection of proteins. An optimized IHC assay using D13C6 showed a range of staining in the tumor stromal compartment in lung and ovarian carcinomas. These observations suggest that use of clone sc-338 produced unreliable results and should not be used for an IHC research grade assay. In addition, this precludes its use as a potential antibody for a clinical diagnostic tool.

Abstract 2647: Merestinib (LY2801653), targeting several oncokinases including NTRK1/2/3, shows potent anti-tumor effect in colorectal cell line- and patient-derived xenograft (PDX) model bearing TPM3-NTRK1 fusion

In cancer, the formation of chimeric gene fusions by genomic rearrangement causes aberrant receptor tyrosine kinase activation resulting in sustained oncogenic signaling driving tumorigenesis. Neurotrophic tyrosine receptor kinase 1 (NTRK1), the cognate receptor for nerve growth factor (NGF), has been reported in 7 tumor types as a NTRK1 kinase domain fused with several reported partners including the 5’ coiled-coil domain of the tropomysin TPM3 gene. The resultant NTRK1 fusion protein is present in about 1.5% of colorectal cancer (CRC), 3% of lung and 12% of papillary thyroid cancers. In addition, gene fusions involving NTRK2 and NTRK3 are present in about 19 different tumor types. Thus pharmacologically targeting NTRK kinase in cancers bearing NTRK fusions may provide treatment options to patients who otherwise might be resistant to standard oncolytic regimens. Merestinib (LY2801653) is an orally bioavailable small molecule inhibitor of several oncokinases, including MET, AXL, ROS1 and MKNK1/2. Merestinib and its two primary metabolites, M1 (LSN2800870) and M2 (LSN2887652) were shown in scanMaxSM kinase binding assays to inhibit all three NTRKs with an IC50 ranging from 15-320 nM, and in the cell-based PathHunter® NTRK1 assay with an IC50 ranging from 12-92 nM. Merestinib, M1 and M2 were evaluated in vitro in TPM3-NTRK1 fusion bearing CRC cells (KM-12). Merestinib, M1 and M2 reduced p-NTRK1 levels, cell proliferation (IC50 of 11 nM, 18 nM and 100 nM respectively) and anchorage independent growth (IC50 of 45 nM, 79 nM and 206 nM respectively). Crizotinib previously reported (Nat Med. 2013;19:1469-72) to have moderate activity against NTRK1, was used to treat a patient with NTRK1 fusion resulted with transient response. Crizotinib was shown here to also reduce p-NTRK1 levels, cell proliferation (IC50 = 88nM) and anchorage independent growth (IC50 = 276nM) in vitro in KM-12 cells. Merestinib treatment at 24 mg/kg once daily arrested tumor growth (T/C = 4%) in KM-12 xenograft tumor bearing mice. Crizotinib administered at 25 mg/kg twice daily in this same model did not result in tumor growth arrest (T/C = 39.5%). Merestinib treatment at 24 mg/kg once daily led to tumor regression in a CRC PDX xenograft model (EL1989) bearing the TPM3-NTRK1 fusion. Crizotinib treatment at 25 mg/kg twice daily in this model did not show tumor regression. Further pre-clinical studies of Merestinib inhibition of NTRK2 and NTRK3 gene fusion are ongoing. These data support the clinical evaluation of Merestinib in patients with tumors harboring NTRK fusion. Merestinib is currently being studied clinically in advanced cancers (NCT01285037).

Citation Format: Bruce W. Konicek, Steve M. Bray, Andrew R. Capen, John N. Calley, Kelly M. Credille, Philip J. Ebert, Gary Heady, Bharvin K. Patel, Victoria L. Peek, Jennifer R. Stephens, Suzane L. Um, Melinda D. Willard, Isabella H. Wulur, Yi Zeng, Richard A. Walgren, Sau-Chi Betty Yan. Merestinib (LY2801653), targeting several oncokinases including NTRK1/2/3, shows potent anti-tumor effect in colorectal cell line- and patient-derived xenograft (PDX) model bearing TPM3-NTRK1 fusion. [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 2647.

The Rat Mammary Gland: Morphologic Changes as an Indicator of Systemic Hormonal Perturbations Induced by Xenobiotics

The development and morphology of the rat mammary gland are dependent upon several hormones including estrogens, androgens, progesterone, growth hormone and prolactin. In toxicology studies, treatment with xenobiotics may alter these hormones resulting in changes in the morphology of reproductive tissues such as the mammary gland. In the rat, male and female mammary glands exhibit striking morphologic differences that can be altered secondary to hormonal perturbations. Recognizing these morphologic changes can help the pathologist predict potential xenobiotic-induced perturbations in the systemic hormonal milieu. This review examines the development of the rat mammary gland and the influence of sex hormones on the morphology of the adult male and female rat mammary gland. Specific case examples from the literature and data from our laboratory highlight the dynamic nature of the rat mammary gland in response to hormonal changes.

Myostatin Neutralization Results in Preservation of Muscle Mass and Strength in Preclinical Models of Tumor-Induced Muscle Wasting

Skeletal muscle wasting occurs in a great majority of cancer patients with advanced disease and is associated with a poor prognosis and decreased survival. Myostatin functions as a negative regulator of skeletal muscle mass and has recently become a therapeutic target for reducing the loss of skeletal muscle and strength associated with clinical myopathies. We generated neutralizing antibodies to myostatin to test their potential use as therapeutic agents to attenuate the skeletal muscle wasting due to cancer. We show that our neutralizing antimyostatin antibodies significantly increase body weight, skeletal muscle mass, and strength in non-tumor-bearing mice with a concomitant increase in mean myofiber area. The administration of these neutralizing antibodies in two preclinical models of cancer-induced muscle wasting (C26 colon adenocarcinoma and PC3 prostate carcinoma) resulted in a significant attenuation of the loss of muscle mass and strength with no effect on tumor growth. We also show that the skeletal muscle mass- and strength-preserving effect of the antibodies is not affected by the coadministration of gemcitabine, a common chemotherapeutic agent, in both non-tumor-bearing mice and mice bearing C26 tumors. In addition, we show that myostatin neutralization with these antibodies results in the preservation of skeletal muscle mass following reduced caloric intake, a common comorbidity associated with advanced cancer. Our findings support the use of neutralizing antimyostatin antibodies as potential therapeutics for cancer-induced muscle wasting.

Identification of LY2510924, a novel cyclic peptide CXCR4 antagonist that exhibits antitumor activities in solid tumor and breast cancer metastatic models

Emerging evidence demonstrates that stromal cell-derived factor 1 (SDF-1) and CXCR4, a chemokine and chemokine receptor pair, play important roles in tumorigenesis. In this report, we describe a small cyclic peptide, LY2510924, which is a potent and selective CXCR4 antagonist currently in phase II clinical studies for cancer. LY2510924 specifically blocked SDF-1 binding to CXCR4 with IC50 value of 0.079 nmol/L, and inhibited SDF-1-induced GTP binding with Kb value of 0.38 nmol/L. In human lymphoma U937 cells expressing endogenous CXCR4, LY2510924 inhibited SDF-1-induced cell migration with IC50 value of 0.26 nmol/L and inhibited SDF-1/CXCR4-mediated intracellular signaling. LY2510924 exhibited a concentration-dependent inhibition of SDF-1-stimulated phospho-ERK and phospho-Akt in tumor cells. Biochemical and cellular analyses revealed that LY2510924 had no apparent agonist activity. Pharmacokinetic analyses suggested that LY2510924 had acceptable in vivo stability and a pharmacokinetic profile similar to a typical small-molecular inhibitor in preclinical species. LY2510924 showed dose-dependent inhibition of tumor growth in human xenograft models developed with non-Hodgkin lymphoma, renal cell carcinoma, lung, and colon cancer cells that express functional CXCR4. In MDA-MB-231, a breast cancer metastatic model, LY2510924 inhibited tumor metastasis by blocking migration/homing process of tumor cells to the lung and by inhibiting cell proliferation after tumor cell homing. Collectively, the preclinical data support further investigation of LY2510924 in clinical studies for cancer.

Autosomal Recessive Congenital Ichthyosis in American Bulldogs Is Associated With NIPAL4 (ICHTHYIN) Deficiency

A minority of patients with nonsyndromic autosomal recessive congenital ichthyosis (ARCI) display mutations in NIPAL4 (ICHTHYIN). This protein plays a role in epidermal lipid metabolism, although the mechanism is unknown. The study describes a moderate form of ARCI in an extended pedigree of American Bulldogs that is linked to the gene encoding ichthyin. The gross phenotype was manifest as a disheveled pelage shortly after birth, generalized scaling, and adherent brown scale with erythema of the abdominal skin. Pedigree analysis indicated an autosomal recessive mode of inheritance. Ultrastructurally, the epidermis showed discontinuous lipid bilayers, unprocessed lipid within corneocytes, and abnormal lamellar bodies. Linkage analysis, performed by choosing simple sequence repeat markers and single-nucleotide polymorphisms near genes known to cause ACRI, revealed an association with NIPAL4. NIPAL4 was identified and sequenced using standard methods. No mutation was identified within the gene, but affected dogs had a SINE element 5' upstream of exon 1 in a highly conserved region. Of 545 DNA samples from American Bulldogs, 32 dogs (17 females, 15 males) were homozygous for the polymerase chain reaction fragment. All affected dogs were homozygous, with parents heterozygous for the insertion. Immunolabeling revealed an absence of ichthyin in the epidermis. This is the first description of ARCI associated with decreased expression of NIPAL4 in nonhuman species.

Abstract 4403: Preclinical evaluation of LY2801653, an orally bioavailable small molecule oncokinase inhibitor, in cholangiocarcinoma models

Cholangiocarcinoma (CCA) is an aggressive and locally invasive biliary tract malignancy with a poor prognosis and no approved drug treatment. LY2801653 is an orally bioavailable small molecule oncokinase inhibitor1 of MET, a receptor reported to be dysregulated and correlated with a poor outcome in CCA. We evaluated additional oncotargets of LY2801653 (MET/HGF, pMET, AXL/pAXL, the MKNK1/2 substrate p-eIF4E, and ROS1) in 7 CCA cell lines (EGI-1, TFK-1, SNU245, SNU478, SNU869, SNU1079, and SNU1196) and 5 CCA patient-derived mouse xenograft (PDX) tumors. Cell line expression of MET, EGFR and p-eIF4E were evaluated by western blot. Although HGF expression was not detected in any of the cell lines by ELISA, pMET was detected in 5 cell lines (not in TFK-1 or SNU1079). ROS1 fusion was not detected in the 7 cell lines using break-apart FISH probes. Very high AXL and pAXL were detected in the SNU1196 line by western blot. Despite the high levels of pAXL, further increases in pAXL were noted after addition of its ligand, Gas6. In the SNU1196 cell line, pAXL expression and cell proliferation were completely inhibited by LY2801653, but not by a MET-specific inhibitor PF4217903. HGF-induced SNU1196 cell migration was inhibited equally well by LY2801653 and PF4217903. Unlike CCA cell line derived mouse xenograft tumors, the 5 PDX tumors retained prominent desmoplastic stroma. As analyzed by immunohistochemistry (IHC), MET was highly expressed in 3 of the 5 PDX tumors, and high levels of p-eIF4E were expressed in all 5. Increased AXL expression (IHC) appeared to be associated with more poorly differentiated PDX tumors.

LY2801653 demonstrated potent in vivo anti-tumor activity in several CCA xenograft models. In a xenograft mouse model with the extrahepatic CCA derived EGI-1 cell line, treatment with LY2801653 at 24 mg/kg dosed twice daily resulted anti-tumor effect of 38.5% (% treated/control). In the SNU869 extrahepatic CCA cell line-derived xenograft mouse model, combination treatment with LY2801653 (12 mg/kg twice daily) and either cisplatin (5 mg/kg once weekly) or gemcitabine (60 mg/kg once weekly) resulted in an additive anti-tumor effect as compared to LY2801653 alone. Moreover, the combination of LY2801653 with gemcitabine resulted in tumor regression in this model. In vivo studies are ongoing with LY2801653 in the extrahepatic SNU1196 CCA cell line-derived xenograft model as well as two of the PDX models. The preclinical data in this study support the ongoing phase 1 clinical evaluation of LY2801653 in cholangiocarcinoma patients (trial I3O-MC-JSBA, NCT01285037). (1 - Yan et al. Invest New Drugs 2013;31:833-44).

Citation Format: Sau-Chi Betty Yan, Suzane L. Um, Victoria L. Peek, Megan N. Thobe, Kelly M. Credille, Jennifer R. Stephens, Jason R. Manro, Darryl W. Ballard, Jessica A. Baker, Joel D. Cook, Bruce W. Konicek, Jeremy R. Graff, Timothy R. Holzer, Richard A. Walgren. Preclinical evaluation of LY2801653, an orally bioavailable small molecule oncokinase inhibitor, in cholangiocarcinoma models. [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 4403. doi:10.1158/1538-7445.AM2014-4403

Abstract 4567: Demonstration of pharmacodynamic effects of Notch and PI3Kinase inhibitors using robust immunohistochemical assays on human skin explant models

Assessment of pharmacodynamic (PD) effect of novel therapeutic compounds in human tissues is used to demonstrate target engagement and to rationalize dosing strategy decisions for emerging targeted therapeutics in clinical trials. Often, human skin biopsies, a readily accessible surrogate tissue, are used for these purposes. Aberrant signaling in the Notch cell surface receptor and the PI3K signal transduction pathways are increasingly implicated in human cancers. In order to test the utility of immunohistochemical (IHC) PD biomarker assays developed in our laboratory for Notch and PI3K inhibitor development programs, we developed ex vivo PD models using respective inhibitors on human skin biopsy explants. Fresh human skin samples were obtained in the Operating-Room from reduction mammoplasty specimens, serially sliced (1-2 mm) and incubated at 37°C in Williams E. media containing 1 µM Notch (gamma-secretase) inhibitor (15 h); and 50 µM PI3K inhibitor (LY294002, 4 h). Specimens were fixed in 10% neutral buffered formalin for 24 hours, and processed into FFPE blocks. Sections were stained for Notch1 intracellular domain (N1ICD, rabbit monoclonal, D3B8) using DAB and for phospho-S6 (S240/S244, rabbit polyclonal) using an alkaline phosphatase-based detection system. N1ICD and phospho-S6 immunoreactivity in cells of the epidermis was analyzed using positive pixel counting. Viability of epidermal cells throughout ex vivo incubation was verified by Ki67 and histomorphologic assessments of the epidermis. Nuclear N1ICD immunoreactivity, a marker of Notch pathway activation, was decreased by 76% when treated with gamma-secretase inhibitor. Similarly, treatment with PI3K inhibitor decreased cytoplasmic phospho-S6 immunoreactivity by 98%. These ex vivo models of human skin provide scientific evidence to support: 1) The N1ICD and phospho-S6 IHC assays developed in our laboratory can demonstrate ex vivo inhibition of these two pathways in human skin; and 2) Feasibility to translate human skin explant findings to patient skin samples from clinical trials. Our explant model systems are closer to real life PD assessments on patient skin samples from clinical trials and can further substantiate the PD data generated in animal models. In some cases, the ex vivo model could replace animal models.

Citation Format: Timothy R. Holzer, Leslie A. O'Neill, Angie D. Fulford, Janet M. Grondin, Bradley L. Ackermann, Robert J. Konrad, Kelly M. Credille, Aejaz Nasir. Demonstration of pharmacodynamic effects of Notch and PI3Kinase inhibitors using robust immunohistochemical assays on human skin explant models. [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 4567. doi:10.1158/1538-7445.AM2014-4567

LY2875358, a neutralizing and internalizing anti-MET bivalent antibody, inhibits HGF-dependent and HGF-independent MET activation and tumor growth

PURPOSE

MET, the receptor for hepatocyte growth factor (HGF), has been implicated in driving tumor proliferation and metastasis. High MET expression is correlated with poor prognosis in multiple cancers. Activation of MET can be induced either by HGF-independent mechanisms such as gene amplification, specific genetic mutations, and transcriptional upregulation or by HGF-dependent autocrine or paracrine mechanisms.

EXPERIMENTAL DESIGN/RESULTS

Here, we report on LY2875358, a novel humanized bivalent anti-MET antibody that has high neutralization and internalization activities, resulting in inhibition of both HGF-dependent and HGF-independent MET pathway activation and tumor growth. In contrast to other bivalent MET antibodies, LY2875358 exhibits no functional agonist activity and does not stimulate biologic activities such as cell proliferation, scattering, invasion, tubulogenesis, or apoptosis protection in various HGF-responsive cells and no evidence of inducing proliferation in vivo in a monkey toxicity study. LY2875358 blocks HGF binding to MET and HGF-induced MET phosphorylation and cell proliferation. In contrast to the humanized one-armed 5D5 anti-MET antibody, LY2875358 induces internalization and degradation of MET that inhibits cell proliferation and tumor growth in models where MET is constitutively activated. Moreover, LY2875358 has potent antitumor activity in both HGF-dependent and HGF-independent (MET-amplified) xenograft tumor models. Together, these findings indicate that the mechanism of action of LY2875358 is different from that of the one-armed MET antibody.

CONCLUSIONS

LY2875358 may provide a promising therapeutic strategy for patients whose tumors are driven by both HGF-dependent and HGF-independent MET activation. LY2875358 is currently being investigated in multiple clinical studies.

A human monoclonal antibody targeting the stem cell factor receptor (c-Kit) blocks tumor cell signaling and inhibits tumor growth

Stem cell factor receptor (c-Kit) exerts multiple biological effects on target cells upon binding its ligand stem cell factor (SCF). Aberrant activation of c-Kit results in dysregulated signaling and is implicated in the pathogenesis of numerous cancers. The development of more specific and effective c-Kit therapies is warranted given its essential role in tumorigenesis. In this study, we describe the biological properties of CK6, a fully human IgG1 monoclonal antibody against the extracellular region of human c-Kit. CK6 specifically binds c-Kit receptor with high affinity (EC 50 = 0.06 nM) and strongly blocks its interaction with SCF (IC 50 = 0.41 nM) in solid phase assays. Flow cytometry shows CK6 binding to c-Kit on the cell surface of human small cell lung carcinoma (SCLC), melanoma, and leukemia tumor cell lines. Furthermore, exposure to CK6 inhibits SCF stimulation of c-Kit tyrosine kinase activity and downstream signaling pathways such as mitogen-activated protein kinase (MAPK) and protein kinase B (AKT), in addition to reducing tumor cell line growth in vitro. CK6 treatment significantly decreases human xenograft tumor growth in NCI-H526 SCLC (T/C% = 57) and Malme-3M melanoma (T/C% = 58) models in vivo. The combination of CK6 with standard of care chemotherapy agents, cisplatin and etoposide for SCLC or dacarbazine for melanoma, more potently reduces tumor growth (SCLC T/C% = 24, melanoma T/C% = 38) compared with CK6 or chemotherapy alone. In summary, our results demonstrate that CK6 is a c-Kit antagonist antibody with tumor growth neutralizing properties and are highly suggestive of potential therapeutic application in treating human malignancies harboring c-Kit receptor.

Systemic mastocytosis in an African fat-tail gecko (Hemitheconyx caudicinctus)

A 3-year-old African fat-tail gecko (Hemitheconyx caudicinctus) suddenly became lethargic and died 2 days later. Necropsy examination revealed a submandibular mass and discolouration of the liver, kidneys and skeletal muscles of the tail. Microscopical evaluation revealed neoplastic mast cells in the skin, liver, kidneys, skeletal muscles, bones, spleen, uterus, ovaries and lungs. Exfoliative cytological, histopathological and ultrastructural features were consistent with systemic mastocytosis. Neoplastic proliferative disorders of mast cells are rare in reptiles and this is the first report of mast cell neoplasia in geckos.

Evaluation of hair loss in cats occurring after treatment with a topical flea control product

BACKGROUND

A formulation containing 39.6% spinetoram resulted in a higher than anticipated number of reports of alopecia at the site of application in the first months following commercial product launch.

HYPOTHESIS/OBJECTIVES

To determine the cause of the alopecia using histopathology, including assessment for inflammation, follicular findings of physical trauma (plucking/pulling behaviour) and changes in follicular cycling.

ANIMALS

Twenty-four flea-free, male and female adult domestic short hair cats within a private research colony.

METHODS

Cats were treated with a single application of 39.6% spinetoram on day 0; personnel were not blinded. Observations of the skin and hair coat began immediately and were repeated at 30 min and 1, 2, 3, 4, 6, 8 and 12 h post-application and then on subsequent days at the same time as initial dosing and at 2, 4, 6, 8 and 12 h after that time, until day 5. If hair thinning or loss was observed, a skin biopsy sample was collected. Two cats not exhibiting abnormalities were biopsied on day 6.

RESULTS

Thirty-eight per cent of cats (nine of 24) developed hair thinning and alopecia of sufficient severity within 78 h post-application of the product to warrant skin biopsy. Abnormalities in the skin were limited to the application site and were consistent with physical trauma (pulling or plucking) to the hair.

CONCLUSIONS AND CLINICAL IMPORTANCE

Microscopic changes in the hair follicles of affected cats were consistent with self-induced trauma or barbering behaviour. All changes were reversible and paralleled findings associated with well-established, topical flea control products.

Inhibition of tumor growth and metastasis in non-small cell lung cancer by LY2801653, an inhibitor of several oncokinases, including MET

PURPOSE

Lung cancer is the leading cause of cancer-related death worldwide. Sustained activation, overexpression, or mutation of the MET pathway is associated with a poor prognosis in a variety of tumors, including non-small cell lung cancer (NSCLC), implicating the MET pathway as a potential therapeutic target for lung cancer. Previously, we reported on the development of LY2801653: a novel, orally bioavailable oncokinase inhibitor with MET as one of its targets. Here, we discuss the evaluation of LY2801653 in both preclinical in vitro and in vivo NSCLC models. Experimental Design/

RESULTS

Treatment with LY2801653 showed tumor growth inhibition in tumor cell lines and patient-derived tumor xenograft models as a single agent (37.4%-90.0% inhibition) or when used in combination with cisplatin, gemcitabine, or erlotinib (66.5%-86.3% inhibition). Mechanistic studies showed that treatment with LY2801653 inhibited the constitutive activation of MET pathway signaling and resulted in inhibition of NCI-H441 cell proliferation, anchorage-independent growth, migration, and invasion. These in vitro findings were confirmed in the H441 orthotopic model where LY2801653 treatment significantly inhibited both primary tumor growth (87.9% inhibition) and metastasis (64.5% inhibition of lymph node and 67.7% inhibition of chest wall). Tumor-bearing animals treated with LY2801653 had a significantly greater survival time (87% increase compared with the vehicle-treated mice). In the MET-independent NCI-H1299 orthotopic model, treatment with LY2801653 showed a significant inhibition of primary tumor growth but not metastasis.

CONCLUSIONS

Collectively, these results support clinical evaluation of LY2801653 in NSCLCs and suggest that differences in the MET activation of tumors may be predictive of response.

Abstract 2339: Prevalence of MET expression, activating mutations of KRAS and IDH1/2, and ROS1 fusions in cholangiocarcinoma patient tumor samples

Cholangiocarcinoma (CCA) originates from biliary tract epithelium and can be classified anatomically into intrahepatic or extrahepatic CCA. Although a relatively rare disease in the United States and Europe, the incidence of intrahepatic CCA is on the rise with unknown causes. CCA incidence is higher in Asia and the etiology is associated with infections such as liver fluke and hepatitis B/C. Prognosis at diagnosis is poor with median survival time of &lt; 1 year, and only 10-20% of patients are eligible for tumor resection at diagnosis. This study examined the prevalence of MET over-expression, activating single point mutations of KRAS and IDH1/2, and ROS1 gene fusions in ∼100 intrahepatic and extrahepatic CCA FFPE tumor tissues obtained from non-Asian (n=40) and Asian (n=60) patients. Immunohistochemistry performed with an anti-MET-specific antibody (A2) demonstrated that MET is expressed in the majority of all intrahepatic CCA samples analyzed, with ∼50% of samples reported with membranocytoplasmic scores of 2+ (moderate intensity) or 3+ (strong intensity) on a 0-3+ scale. Interestingly, most non-malignant bile ducts and much vascular endothelia also stained lightly positive for MET. To determine mutation frequencies of KRAS and IDH1/2, competitive allele-specific Taqman® PCR (castPCR) was performed on DNA extracted from FFPE CCA tissue (limit of mutation detection 0.1%). Fourteen KRAS activating mutations (G12S, G12R, G12A, G13C, G13S, G13R, G12D, G13D, G12V, G12C, Q61R, Q61L, Q61H (c.183A&gt;C and c.183A&gt;T for Q61H), 5 IDH1 mutations (R132G, R132S, R132H, R132C, R132L), and 5 IDH2 mutations (R172G, R172M, R172K, R172W, R172S) were analyzed. Overall, 25% of analyzed samples were positive for KRAS mutation, and G12D was the predominant mutation (∼60%). One-third of Asian samples were positive for KRAS mutation, whereas less than one-fifth of non-Asian samples contained KRAS mutations. For IDH1, the frequency of mutation was less than 10% overall, and the majority of patients with IDH1 mutations were non-Asian. The R132C mutation was the predominant IDH1 mutation, and all tissues that were positive for IDH1 mutations were of intrahepatic origin. Interestingly, 2 out of the 7 samples positive for IDH1 mutations (R132C) were also positive for G12D KRAS mutation. There is no trend of MET expression correlating with either KRAS or IDH1 mutations. IDH2 analyses by castPCR and FISH studies examining ROS1 gene fusion are ongoing. Based on these data, inhibitors of receptor tyrosine kinases and their signaling pathways such as MET and ROS1 may merit clinical evaluation in CCA patients. LY2801653, a MET inhibitor which also has inhibitory activity against ROS1 and MKNK1/2 is currently in phase 1 clinical testing in patients with advanced cancer (trial I3O-MC-JSBA, NCT01285037).

Citation Format: Megan N. Thobe, S. Betty Yan, Kelly M. Credille, Aejaz Nasir, Jessica A. Roseberry Baker, Mary Lajiness, Nathan A. Brooks, Darryl W. Ballard, Donna M. Farley, Victoria L. Peek, Suzane L. Um, G. Jason Jin, Raymond Gilmour, Christoph Reinhard, Jeremy R. Graff, Andrew E. Schade, Aaron M. Gruver, Bruce Colligan, Larry Douglass, Julia Carter, Richard A. Walgren. Prevalence of MET expression, activating mutations of KRAS and IDH1/2, and ROS1 fusions in cholangiocarcinoma patient tumor samples. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2339. doi:10.1158/1538-7445.AM2013-2339

Abstract 2087: Detection of KRAS mutations in circulating tumor cells (CTCs) and in formalin-fixed, paraffin-embedded (FFPE) tissue using castPCR method

CTCs are tumor cells in circulation in the blood and are believed to be shed from both the primary and metastatic tumors. CTC counts are prognostic of survival in metastatic breast, colorectal, and prostate cancers. It is postulated that these cells are genetically similar to cells comprising the patient's tumor(s). The presence of these cells in blood provides a minimally invasive source of nucleic acid for serial monitoring of tumors for disease progression and emergence of drug treatment resistance without the risks of traditional solid tumor biopsy. Activating mutations in the KRAS gene are frequently found in human cancers (up to 30% of cancer cases), and are present in a large portion of non-small cell lung cancer (NSCLC), pancreatic, and colorectal cancers. Reported mutations are mostly single point mutations in codons 12, 13 and 61, with the majority of mutations present in codon 12. Importantly, KRAS mutation status can be predictive of response to treatment, and may be used to determine the best therapeutic strategy. Therefore, it is critical to develop a robust method for detecting mutations from a limited number of enriched tumor cells (e.g. CTCs or fine needle aspirate) in a high background of normal cells. Our studies utilize competitive allele-specific PCR (castPCR) for detecting mutant KRAS from human cancer cells spiked into and retrieved from blood, and from fixed cells embedded in paraffin. This technology is reportedly capable of detecting one mutant allele molecule in 10 million wild-type molecules. KRAS is mutated in human NSCLC H441 cells (G12V) and in KP-4 pancreatic cells (G12D). After spiking H441 and KP-4 cells into human blood, cells were captured/enriched and enumerated by the Veridex CellTracks™ system. Both CXC and Profile kits (Veridex) were used. Recovered cells were then lysed overnight with Arcturus® PicoPure® DNA extraction lysis buffer, and the resulting DNA was analyzed for mutant KRAS with the castPCR TaqMan® Mutation Detection Assay (Applied Biosystems) specific for the mutation found in H441 cells (G12V). Under these conditions, we detected KRAS mutation in H441 cells with robust sensitivity (20 spiked cells into 7.5ml of blood; KP-4 cells were negative for the G12V mutation). To further examine if this method could be used for detecting mutations in human tissue, FFPE tumor cells were analyzed. The WaxFreeTM DNA kit (TrimGen) was used to extract DNA from FFPE cells, and castPCR was performed. H441 mutant KRAS was detected from as little as ∼200 pg DNA (100-fold dilution of DNA). Ongoing studies involve correlating mutation status between CTCs and tumor FFPE tissue. These data will aid in clinical biomarker development used in clinical trials and improve methods to determine the most beneficial treatment options for patients. Importantly, this approach may enable patients to be serially monitored for tumor mutation status with blood draws.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2087. doi:1538-7445.AM2012-2087

Hematopoietic proliferative lesions in the spleen of rasH2 transgenic mice treated with MNU

In this study, rasH2-Tg mice treated with N-methyl-N-nitrosurea (MNU) developed exuberant hematoproliferative changes in the spleen that included dysplasia and features of neoplasia. Hematoproliferative change was characterized as exuberant proliferation of hematopoietic cells within the spleen that distorted but did not displace normal splenic morphologic features. The hematopoietic cells were of mixed lineage, but one type, often erythroid, predominated. Cellular atypia was present in all mice with hematoproliferative change, and dysplasia was present in five of eight examined. Hematoproliferative neoplasia was characterized by similar cytologic features but also resulted in displacement/disruption of normal splenic architecture and increased numbers of unidentified blast cells. One case was differentiated toward myeloid proliferation, suggesting granulocytic leukemia. Affected mice had other neoplasms, such as lymphoma and anemia. These proliferative and dysplastic lesions of the spleen in rasH2-Tg mice treated with MNU require additional characterization to definitively differentiate them from the reactive hematopoiesis that can occur in response to inflammatory, neoplastic, or hematopoietic insults in mice.

Abstract B188: Inhibition of Notch signaling for the treatment of cancer

The Notch pathway is a highly conserved signaling system that plays an important role in development and tissue homeostasis. While Notch mutations are well characterized and implicated in hematological malignancies such as T-cell acute lymphoblastic leukemia, in solid tumors ligand or receptor over-expression may lead to enhanced/sustained Notch function, triggering increased tumor cell proliferation/survival, angiogenesis and tumor formation. In order to delineate an oncogenic role of activated Notch in tumors of epithelial origin, we carried out a series of in-vitro and in-vivo studies. We demonstrated that the activated Notch1 receptor (a - secretase-dependent Notch1 E with the transmembrane domain and a-secretase-independent constitutively activated Notch1 intracellular fragment) can transform normal rat cells, RK3E. These transformed cells formed colonies in soft agar, confirming their anchorage-independent growth potential, and when implanted subcutaneously, formed tumors in athymic nude mice. Inhibition of Notch signaling through a small molecule inhibitor of -secretase, a key regulator of Notch processing, may provide an attractive targeted cancer therapeutic strategy. We have identified and characterized a novel small molecule that is an exquisitely potent inhibitor of Notch signaling in tumor cell lines and endothelial cells with an IC50 ranging from 0.005 nM to 20 nM. The Notch inhibitor meets all pharmacokinetic criteria in pre-clinical species. In a xenograft tumor model, the novel compound inhibited Notch cleavage in a dose-dependent manner at 6 hours after a single oral dose. This inhibition of Notch cleavage resulted in the induction of apoptosis (as measured by activated caspase-3 levels) that was statistically significant at 24 hours after a single oral dose of 3 mg/kg. Analysis of tumors from animals treated with the Notch inhibitor revealed inhibition of angiogenesis through formation of leaky vasculature which may also contribute to observed anti-tumor activity. Furthermore, Notch inhibition produced tumor regression in the Notch-dependent tumor models. Anti-tumor activity was also observed in several human xenograft tumors of epithelial origin. To mitigate mucoid gasteroentropathy due to Notch inhibition, PK/PD data were incorporated in devising dosing strategies that identified an optimal intermittent dosing schedule without negatively impacting efficacy. Furthermore, the mucoid gastroentropathy was also mitigated by the prophylactic administration of dexamethasone without negatively impacting Notch inhibitor mediated efficacy. In summary, we have characterized an orally bio-available small molecule Notch inhibitor that may provide therapeutic benefit to cancer patients.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):B188.

Ultrasensitive Cross-species Measurement of Cardiac Troponin-I Using the Erenna Immunoassay System

Serum cardiac troponin-I (cTnI) has been validated as a biomarker for cardiotoxicity in numerous animal models; however, owing to sensitivity issues cTnI concentrations in healthy, resting animals used in toxicology studies have not been established. Serum from healthy and isoproterenol hydrochloride (iso)-treated rats, dogs, and monkeys were assayed using the Erenna system. The Erenna cTnI assay provided sensitivity < 1 ng/L across human, rat, dog, and monkey cTnI. Linear responses ( R2= 0.99) were observed for all species. Precision studies yielded interassay CVs of curve fit quantification from 2% to 4% between 1.6 and 5000 ng/L, and 23% at 0.78 ng/L. Strong correlation ( R2= 0.99) was obtained between Erenna and Beckman Access cTnI. Concentrations of cTnI in healthy animals ranged from 1 to 9 ng/L. In longitudinal studies of iso-treated animals, the concentrations of cTnI in the control vehicle-treated groups were 10–20 ng/L for rats (N = 10) and predose values of 2–3 ng/L for dogs (N = 3). Measured with the Erenna assay system, cTnI was quantifiable at all time intervals tested in all animals treated with iso. The Erenna system provides sensitive measurement of cTnI in rats, dogs, and monkeys, makes it possible to determine small changes from normal concentrations, and provides cTnI values from small volumes of serum.

The clinical and morphologic features of nonepidermolytic ichthyosis in the golden retriever

A scaling disorder specific to Golden Retriever dogs has been recognized by both dermatologists and pathologists, but to date has not been well characterized. At the University of Pennsylvania's Laboratory of Toxicology and Pathology, 46 cases of ichthyosis were diagnosed histologically in Golden Retriever dogs from January 2004 to January 2007. A total of 22 dogs had skin lesions documented at younger than 1 year of age; 3 dogs between 1 and 2 years of age; 13 dogs developed lesions at older than 2 years; and the time of onset was unknown for 8 dogs. A total of 25 dogs were female, and 21 were male. All dogs had strikingly similar histopathologic changes that consisted of mild to moderate laminar orthokeratotic hyperkeratosis with an absence of epidermal hyperplasia and dermal inflammation. Ultrastructural analysis using a ruthenium tetroxide fixation method was performed on punch biopsy samples from 5 dogs and compared with 2 control dogs (1 clinically and histologically normal sibling of an affected dog and 1 Cairn Terrier). All affected dogs had retained and convoluted membranes with crystalline structures in the stratum corneum. Scattered keratinocytes in the granular cell layer had prominent, clear, membrane-bound, cytoplasmic vacuoles. Pedigree analysis of 14 dogs was compatible with autosomal recessive inheritance, but incomplete dominance could not be ruled out. This unique hyperkeratotic/scaling disorder in Golden Retrievers has distinctive clinical, histologic, and ultrastructural features, which are consistent with a primary cornification defect.

Fabp3 as a biomarker of skeletal muscle toxicity in the rat: comparison with conventional biomarkers

Fatty acid binding protein 3 (Fabp3) has been used as a serological biomarker of cardiac injury, but its utility as a preclinical biomarker of injury to skeletal muscle is not well described. Fabp3 concentrations were determined for tissues from Sprague-Dawley rats and found to occur at highest concentrations in cardiac muscle and in skeletal muscles containing an abundance of type I fibers, such as the soleus muscle. Soleus is also a primary site of skeletal muscle (SKM) injury caused by lipid-lowering peroxisome proliferator-activated receptor alpha (PPAR-alpha) agonists. In rats administered repeat doses of a PPAR-alpha agonist, the kinetics and amplitude of plasma concentrations of Fabp3 were consistent with plasma compound concentrations and histopathology findings of swollen, hyalinized, and fragmented muscle fibers with macrophage infiltration. Immunohistochemical detection of Fabp3 revealed focal depletion of Fabp3 protein from injured SKM fibers which is consistent with increased serum Fabp3 concentrations in treated rats. We then assessed the predictivity of serological Fabp3 for SKM necrosis in short duration toxicology studies. Rats were treated with various doses of 27 different compounds, and the predictivity of serological biomarkers was assessed relative to histology in individual rats and in treatment groups. Under these study conditions, Fabp3 was the most useful individual biomarker based on concordance, sensitivity, positive and negative predictive values, and false negative rate. In addition, the combination of Fabp3 and aspartate aminotransferase (AST) had greater diagnostic value than the conventional combination of creatine kinase-MM isoenzyme (CK) and AST.

Linkage of dermatomyositis in the Shetland Sheepdog to chromosome 35

Dermatomyositis is an inflammatory disease of the skin and muscle and is most commonly found in the Shetland sheepdog. Both the clinical presentation and the age of onset of dermatomyositis vary widely, and the inability to diagnose dermatomyositis before clinical symptoms ensue has made control of the disease difficult. Identification of a genetic marker that cosegregates with dermatomyositis would facilitate the development of a DNA-based test for the early detection of affected dogs. We report the use of linkage disequilibrium (LD) mapping to identify linkage to phenotypic dermatomyositis in the Shetland sheepdog. One marker, microsatellite marker FH3570 on canine chromosome 35, had evidence of LD (P=0.00002). Further studies are necessary to narrow the region harbouring the dermatomyositis locus, identify candidate genes and determine mode of inheritance.

Preservation of phenotype in an organotypic cell culture model of a recessive keratinization defect of Norfolk terrier dogs

The purpose of this study is to reproduce in vitro a recessive keratinization defect of Norfolk terrier dogs characterized by a lack of keratin 10 (K10) production. Keratinocytes from skin biopsy samples of four normal dogs and two affected dogs were cultured organotypically with growth factor-supplemented media in order to stimulate cornification. The cultured epidermis from the normal dogs closely resembled the normal epidermis in vivo and cornified. The cultured epidermis from the affected dogs displayed many phenotypic alterations identified in skin biopsies from dogs with this heritable defect. Immunohistochemistry and immunoblotting showed a marked decrease in K10 from the cultures of the affected keratinocytes, compared to that in K10 from the cultures of the normal keratinocytes. Real-time reverse transcription polymerase chain reaction quantitation showed a 31-fold decrease in K10, a 1.75-fold increase in K1 and a 136-fold increase in K2e between the affected and the normal epidermis. Organotypic keratinocytes showed a 241-fold decrease in K10, a 31-fold decrease in K1 and a 1467-fold decrease in K2e between the affected and normal cultures. Although in vitro keratin expression did not precisely simulate in vivo, the morphology of the normal and the affected epidermis was largely preserved; thus, this culture system may provide an alternative to in vivo investigations for cutaneous research involving cornification.

Mild recessive epidermolytic hyperkeratosis associated with a novel keratin 10 donor splice-site mutation in a family of Norfolk terrier dogs

BACKGROUND

Epidermolytic hyperkeratosis in humans is caused by dominant-negative mutations in suprabasal epidermal keratins 1 and 10. However, spontaneous keratin mutations have not been confirmed in a species other than human.

OBJECTIVES

To describe an autosomal recessive, mild, nonpalmar/plantar epidermolytic ichthyosis segregating in an extended pedigree of Norfolk terrier dogs due to a splice-site mutation in the gene encoding keratin 10 (KRT10).

METHODS

Dogs were evaluated clinically, and skin samples were examined by light and electron microscopy. Genomic DNA samples and cDNA from skin RNA were sequenced and defined a mutation in KRT10. Consequences of the mutation were evaluated by assessing protein expression with immunohistochemistry and Western blotting and gene expression with real-time RT-PCR (reverse transcriptase-polymerase chain reaction).

RESULTS

Adult dogs with the disease had generalized, pigmented hyperkeratosis with epidermal fragility. Light microscopic examination defined epidermolysis with hyperkeratosis; ultrastructural changes included a decrease in tonofilaments and abnormal filament aggregation in upper spinous and granular layer keratinocytes. Affected dogs were homozygous for a single base GT-->TT change in the consensus donor splice site of intron 5 in KRT10. Keratin 10 protein was not detected with immunoblotting in affected dogs. Heterozygous dogs were normal based on clinical and histological appearance and keratin 10 protein expression. The mutation caused activation of at least three cryptic or alternative splice sites. Use of the cryptic sites resulted in transcripts containing premature termination codons. One transcript could result in shortening of the proximal portion of the 2B domain before the stutter region. Quantitative real-time PCR indicated a significant decrease in KRT10 mRNA levels in affected dogs compared with wild-type dogs.

CONCLUSIONS

This disease is the first confirmed spontaneous keratin mutation in a nonhuman species and is the first reported recessive form of epidermolytic hyperkeratosis.

Comparative sequence analysis and radiation hybrid mapping of two epidermal type II keratin genes in the dog: keratin 1 and keratin 2e

In order to extend knowledge of the process of cornification across species and to be better able to recognize inborn errors in keratin synthesis in the dog, we describe the organization and chromosome mapping of canine KRT1 and KRT2E and compare these results to human and murine sequence data. The coding regions of KRT1 and KRT2E are 1,860 bp and 1,902 bp respectively, distributed over nine exons. Both genes are localized on the canine radiation hybrid map to chromosome 27 in the type II keratin gene cluster close to polymorphic markers. These genes are highly conserved across species and based on both genomic and amino acid sequences, canine KRT1 and KRT2E share greater homology with humans than with mice.

A Heritable Keratinization Defect of the Superficial Epidermis in Norfolk Terriers

Although well-characterized in man, abnormal cornification secondary to heritable superficial keratin defects is rarely reported in animals. This report describes a mild cornification defect in seven related Norfolk terrier dogs. Lesions were present at birth and pedigree analysis suggested an autosomal recessive mode of inheritance. The affected dogs had hyperpigmented skin with scaling following mild trauma. The lesions were generalized but most prominent in the glabrous skin of the axillary and inguinal regions-areas where the epidermis is not protected by hair and is subject to frequent trauma. The most striking histological change was vacuolation in the upper epidermis, which often resulted in epidermolysis and blister formation. All of the affected dogs showed similar gross and histological changes. Ultrastructural changes included abnormal keratin filament clumping, prominent clear spaces in the cytoplasm of suprabasal keratinocytes, and abnormal keratohyaline granules. Immunohistochemical labelling for keratin 10 demonstrated a lack of expression in the superficial epidermis of affected dogs. All of the morphological changes noted in the Norfolk terriers were consistent with a mild form of a heritable defect in superficial keratin synthesis.

Digging up the canine genome – a tale to wag about

There is incredible morphological and behavioral diversity among the hundreds of breeds of the domestic dog, CANIS FAMILIARIS. Many of these breeds have come into existence within the last few hundred years. While there are obvious phenotypic differences among breeds, there is marked interbreed genetic homogeneity. Thus, study of canine genetics and genomics is of importance to comparative genomics, evolutionary biology and study of human hereditary diseases. The most recent version of the map of the canine genome is comprised of 3,270 markers mapped to 3,021 unique positions with an average intermarker distance of approximately 1 Mb. The markers include approximately 1,600 microsatellite markers, about 1,000 gene-based markers, and almost 700 bacterial artificial chromosome-end markers. Importantly, integration of radiation hybrid and linkage maps has greatly enhanced the utility of the map. Additionally, mapping the genome has led directly to characterization of microsatellite markers ideal for whole genome linkage scans. Thus, workers are now able to exploit the canine genome for a wide variety of genetic studies. Finally, the decision to sequence the canine genome highlights the dog's evolutionary and physiologic position between the mouse and human and its importance as a model for study of mammalian genetics and human hereditary diseases.

Evaluation of systemic immunologic hyperreactivity after intradermal testing in horses with chronic laminitis

OBJECTIVE

To determine whether systemic immunologic hyperreactivity exists in horses with chronic laminitis, compared with responses for nonlaminitic horses.

ANIMALS

7 nonlaminitic horses and 7 CL horses.

PROCEDURE

In experiment 1, intradermal testing (IDT) was performed on 7 nonlaminitic and 7 CL horses to evaluate the response to a combination of 70 allergens at 15 and 30 minutes and 4 and 24 hours after injection. Three nonlaminitic and 3 CL horses used in experiment 1 were used in experiment 2 to determine whether histologic differences existed between the 2 groups. The H&E-stained tissue sections were evaluated on the basis of 3 criteria. For all analyses, 2-sample t-tests were used to determine significant differences between the groups.

RESULTS

In experiment 1, CL horses had significantly higher total responses to IDT than nonlaminitic horses at the first 3 time periods. Also, CL horses had significantly fewer total scores of 0 than nonlaminitic horses at all time periods, except at 24 hours. In experiment 2, we did not detect significant differences between groups for any criterion.

CONCLUSIONS AND CLINICAL RELEVANCE

Results support the hypothesis that CL horses develop hyperreactivity to various antigenic stimuli, compared with responses for nonlaminitic horses. Therefore, the possibility that antigenic challenge may result in exacerbation of clinical signs of laminitis should be discussed with horse owners. Chronic laminitis should also be a consideration when a horse becomes lame following antigenic challenges.

The effects of thyroid hormones on the skin of beagle dogs

The effects of hypothyroidism on canine skin were determined by comparing morphologic, morphometric, and hair cycle differences in skin biopsy samples from 3 groups of age- and gender-matched Beagle dogs: (1) euthyroid dogs; (2) dogs made hypothyroid by administration of 131I; and (3) dogs made hypothyroid and maintained in a euthyroid state by treatment with synthetic thyroxine. After 10 months of observation, there was slower regrowth of hair 2 months after clipping in the untreated-hypothyroid dogs. Untreated-hypothyroid dogs had a greater number of follicles in telogen and fewer hair shafts (ie, a greater number of hairless telogen follicles) than did the control group. The control dogs had a greater number of telogen follicles but the same number of hair shafts as the treated-hypothyroid group. Treated-hypothyroid dogs had the greatest number of follicles in the growing stage of the hair cycle (anagen). This study suggests that, at least in Beagles, induced hypothyroidism does not affect the pelage as dramatically as has been described in naturally occurring disease. This is because normal Beagles retain hair shafts in follicles for long periods, and the alopecia of hypothyroidism appears to evolve slowly because of the prolongation of this haired telogen stage. The evaluation of thyroxine-treated hypothyroid dogs demonstrates that thyroid hormone supplementation of Beagle dogs with induced hypothyroidism stimulates hair growth.

Sebaceous adenitis in the Akita: clinical observations, histopathology and heredity

Ninety-seven pure-bred Akitas were examined clinically and histologically for sebaceous adenitis. The diagnosis was established histologically in 23 Akitas by demonstrating an inflammatory reaction targeted against the sebaceous glands or a reduction in the number of glands. The clinical course of sebaceous adenitis in the Akita was similar to that seen in other breeds. The first skin lesions occurred mainly on the dorsal midline and ears. Compared with the Poodle, the age at first onset of the disease was more variable and the hair loss affected mainly the undercoat. The progression of sebaceous gland destruction varied between dogs and was not seen in all cases. Because bud-like sebaceous gland proliferation could be identified, it seems that regeneration of the sebaceous glands may occur. An autosomal recessive inheritance appears to be possible. Apart from a genetic background, immune-mediated factors possibly influence the onset and course of sebaceous adenitis.

DNA sequence and physical mapping of the canine transglutaminase 1 gene

The transglutaminase 1 gene (TGM1) encodes an enzyme necessary for cross-linking the structural proteins that form the cornified envelope, an essential component of the outermost layer of the skin, the stratum corneum. Reported here is the complete coding region of canine TGM1, its chromosome localization, and its map position in the integrated canine linkage-radiation hybrid map. Canine TGM1 consists of 2,448 nucleotides distributed over 15 exons. The nucleotide sequence has 90% identity to human TGM1. The deduced canine TGM1 protein is 816 amino acids long and is 92% identical to human TGM1. Using fluorescence in situ hybridization, we localized canine TGM1 to dog (Canis familiaris) chromosome 8 (CFA 8q). Canine TGM1 localized to CFA 8 on the integrated linkage-radiation hybrid map in the interval FH2149-MYH7. Characterizing the coding region of canine TGM1 is a first step in examining the role of this enzyme in normal and defective cornification in the dog.

Severe polysaccharide storage myopathy in Belgian and Percheron draught horses

A severe myopathy leading to death or euthanasia was identified in 4 Belgian and 4 Percheron draught horses age 2-21 years. Clinical signs ranged from overt weakness and muscle atrophy in 2 horses age 2 and 3 years, to recumbency with inability to rise in 6 horses age 4-21 years. In 5 horses there was mild to severe increases in muscle enzyme levels. Clinical diagnoses included equine motor neuron disease (2 horses), post anaesthetic myopathy (2 horses), exertional myopathy (2 horses), myopathy due to unknown (one horse), and equine protozoal myelitis (one horse). Characteristic histopathology of muscle from affected horses was the presence of excessive complex polysaccharide and/or glycogen, revealed by periodic acid-Schiff staining in all cases and by electron microscopy in one case. Evaluation of frozen section histochemistry performed on 2 cases indicated that affected fibres were Type 2 glycolytic fibres. Subsarcolemmal and intracytoplasmic vacuoles were most prominent in 3 horses age 2-4 years, and excessive glycogen, with little or no complex polysaccharide, was the primary compound stored in affected muscle in these young horses. Myopathic changes, including fibre size variation, fibre hypertrophy, internal nuclei, and interstitial fat infiltration, were most prominent in 5 horses age 6-21 years, and the accumulation of complex polysaccharide appeared to increase with age. Mild to moderate segmental myofibre necrosis was present in all cases.

Negative pressure pulmonary edema as a post-anesthetic complication associated with upper airway obstruction in a horse

An 8-year-old Trakehner mare developed fulminant pulmonary edema following suspected upper airway obstruction 50 minutes into an otherwise unremarkable anesthetic recovery after surgery for left cricoarytenoideus dorsalis muscle reinnervation and ventriculocordectomy. Establishing a patent airway by orotracheal reintubation and cardiopulmonary resuscitation attempts were unsuccessful. Gross, histological, and electron microscopic postmortem examination showed severe hemorrhagic pulmonary edema. Laryngeal swelling or hemorrhage were not evident, suggesting laryngospasm or functional airway collapse associated with the underlying left laryngeal paralysis, as a cause of the upper airway obstruction. Negative pressure pulmonary edema is rarely reported in the veterinary literature as a postanesthetic complication.

Biomechanical and histological evaluation of a laparoscopic stapled gastropexy technique in dogs

The biochemical holding strength and histological characteristics of a laparoscopic stapled gastropexy (LG) adhesion were compared with that of an incisional gastropexy (IG) adhesion. An LG was performed in 14 dogs and an IG was performed in six dogs. During the LG procedure, the abdomen was insufflated with carbon dioxide and three cannulae were placed in the caudal aspect of the right side of the abdomen. A 35 mm laparoscopic stapler was used to staple the gastric antrum to the adjacent right lateral abdominal wall. The IG procedure was performed through ventral midline celiotomy. A 35 mm IG was made by apposing the gastric antrum to the adjacent right lateral abdominal wall with two continuous rows of suture. Half of each group of dogs was euthanatized at 7 and 30 days after surgery. The mean tensile load to failure at 7 days was 44.86 +/- 18.54 N for the LG group and 85.33 +/- 23.59 N for the IG group (P < .05). At 30 days the values were 72.39 +/- 18.01 N for the LG group and 71.17 +/-12.11 N for the IG group (P = .41). The gastropexy adhesions in the 7-day postoperative group contained variable amounts of fibrin, hemorrhage, mononuclear cell inflammation, loose fibrovascular tissue, and mature collagenous connective tissue. Adhesions in the 7-day postoperative group were divided subjectively into three histological subgroups based on the relative amounts of mature connective tissue within the adhesion. The LG and IG adhesions were randomly distributed among these subgroups (P = 1.0). Adhesions in the 30-day postoperative group contained well-organized fibrous connective tissue. No difference in the amount of connective tissue could be detected histologically in the LG or IG adhesions. Complications with the LG procedure included stomach perforation (2 cases), splenic puncture (2 cases), and subcutaneous emphysema (4 cases).

Parasitic meningoencephalitis in nurse sharks (Ginglymostoma cirratum)

Based on microscopic examination of the brains of seven wild-caught nurse sharks (Ginglymostoma cirratum), we observed a severe meningoencephalitis associated with numerous parasitic granulomas. The parasites were larval nematodes with morphological characteristics of the Superfamily Dracunculoidea. Although meningeal larval aggregates were associated with chronic inflammation, additional parasitic nodules found on the endocardial surface and perimandibular region did not provoke an inflammatory response. Neither the route of infection nor life cycle were determined.