Citations

Abstract Malignant transformation is commonly associated with dysregulated ribosome biogenesis and for more than 100 years, pathologist have utilized the increase in size and number of nucleoli, the site of ribosome biogenesis as a marker for aggressive malignancies. Recently we demonstrated that hyperactivated RNA Polymerase I (Pol I) transcription, a rate limiting step in ribosome biogenesis, can be specifically targeted by the small molecule inhibitor, CX-5461. When evaluated for its anti-proliferative activity against a panel of genetically diverse human cancer cell lines, those derived from p53 wild type haemotological malignancies were the most sensitive (Drygin et al., Cancer Research, 2011). Evaluation of whether Pol I transcription inhibition could serve as therapeutic strategy in vivo revealed that CX-5461 administration significantly prolongs the overall survival of Eμ-Myc lymphoma bearing mice (Bywater et al., Cancer Cell, 2012). This survival advantage was associated with rapid activation of the ribosomal protein (Rp)-MDM2-p53 nucleolar stress response (Deisenroth et al., Oncogene, 2010) and subsequent induction of tumour-specific p53-dependent apoptosis (Bywater et al. Cancer Cell, 2012). New data and future directions: To further explore the therapeutic potential of Pol I transcription inhibition in haemotological cancers that are refractory to standard therapy, we employed mouse models of MLL-driven Acute Myeloid Leukemia (AML) (MLL/AF9 + Nras and MLL/ENL + Nras) (Zuber et al., Genes Dev, 2009) and V*κ-Myc-driven Multiple Myeloma (MM) (Chesi et al. Cancer Cell, 2009). CX-5461 administration significantly increased the overall survival time of AML-bearing mice (MLL/ENL Nras 17 days for vehicle vs 36 days for drug, P<0.0001; MLL/AF9 Nras 15 days for vehicle vs 23 days for drug, P 0.0009))without severe adverse effects. The extended survival of MLL-driven AML bearing mice was associated with acute activation of p53, an aberrant G2/M cell cycle progression and consequently a delay in tumour progression as monitored by bioluminescence-imaging. In contrast to CX-5461, treatment of AML -bearing mice with Cytarabine/Doxorubicin, a regime used as standard-therapy in the clinic failed to induce p53 in MLL-driven AML resulting in a significantly less survival time than for CX-5461. In ongoing experiments with MM-bearing mice, chronic CX-5461 administration robustly reduced the secretion of serum monoclonal Ig, as detected by serum protein electrophoresis (SPEP), and significantly prolonged survival time demonstrating that CX-5461 possess potent anti-tumour activity in this highly refractory MM model. Analysis of the molecular mechanism responsible for the therapeutic benefit of CX-5461 in MM is ongoing but appears to involve both p53 mediated apoptosis and aberrant cell cycle progression. Conclusion: These data demonstrate that hyperactivated Pol I transcription can be successfully targeted through small molecule inhibitors to therapeutically treat models of human AML and MM that are refractory to standard therapy.. Based on these and published results (Bywater et al., Cancer Cell 2012) and a favorable toxicology profile, we have launched a first-in-human clinical trial of this first in class drug, CX-5461 in patients with hematological malignancies. The outcomes of this trial will offer valuable insights as to whether inhibition of ribosome synthesis might offer a new non-genotoxic therapy approach in the fight against cancers, which are highly refractory to standard-therapies. Citation Format: Nadine Hein, Denis Drygin, Sean O'Brien, Carleen Cullinane, Geoff Matthews, Marta Chesi, Leif Bergsagel, Johannes Zuber, Scott Lowe, Ricky Johnstone, Rick Pearson, Grant McArthur, Ross Hannan. Inhibition of RNA Polymerase I transcription by CX-5461 as a therapeutic strategy for the cancer-specific activation of p53 in highly refractory haematological malignancies. [abstract]. In: Proceedings of the Third AACR International Conference on Frontiers in Basic Cancer Research; Sep 18-22, 2013; National Harbor, MD. Philadelphia (PA): AACR; Cancer Res 2013;73(19 Suppl):Abstract nr B16.

AbstractBackgroundChronic gastrointestinal dysmotility greatly impacts the quality of life. Treatment options are limited and generally symptomatic. Neural autoimmunity is an under‐recognized etiology. We evaluated immunotherapy as an aid to diagnosing autoimmune gastrointestinal dysmotility (AGID).MethodsTwenty‐three subjects evaluated at the Mayo Clinic for suspected AGID (August 2006–February 2014) fulfilled the following criteria: (1) prominent symptoms of gastrointestinal dysmotility with abnormalities on scintigraphy–manometry; (2) serological evidence or personal/family history of autoimmune disease; (3) treated by immunotherapy on a trial basis, 6–12 weeks (intravenous immune globulin, 16; or methylprednisolone, 5; or both, 2). Response was defined subjectively (symptomatic improvement) and objectively (gastrointestinal scintigraphy/manometry studies).Key ResultsSymptoms at presentation: constipation, 18/23; nausea or vomiting, 18/23; weight loss, 17/23; bloating, 13/23; and early satiety, 4/23. Thirteen patients had personal/family history of autoimmunity. Sixteen had neural autoantibodies and 19 had extra‐intestinal autonomic testing abnormalities. Cancer was detected in three patients. Preimmunotherapy scintigraphy revealed slowed transit (19/21 evaluated; gastric, 11; small bowel, 12; colonic, 11); manometry studies were abnormal in 7/8. Postimmunotherapy, 17 (74%) had improvement (both symptomatic and scintigraphic, five; symptomatic alone, eight; scintigraphic alone, four). Nine responders re‐evaluated had scintigraphic evidence of improvement. The majority of responders who were re‐evaluated had improvement in autonomic testing (six of seven) or manometry (two of two).Conclusions & InferencesThis proof of principle study illustrates the importance of considering an autoimmune basis for idiopathic gastrointestinal dysmotility and supports the utility of a diagnostic trial of immunotherapy.

Abstract Background There is increasing evidence for specific cellular changes in the stomach of patients with diabetic ( DG ) and idiopathic ( IG ) gastroparesis. The most significant findings are loss of interstitial cells of Cajal ( ICC ), neuronal abnormalities, and an immune cellular infiltrate. Studies done in diabetic mice have shown a cytoprotective effect of CD 206+ M2 macrophages. To quantify overall immune cellular infiltrate, identify macrophage populations, and quantify CD 206+ and i NOS + cells. To investigate associations between cellular phenotypes and ICC . Methods Full thickness gastric body biopsies were obtained from non‐diabetic controls (C), diabetic controls ( DC ), DG , and IG patients. Sections were labeled for CD 45, CD 206, Kit, i NOS , and putative human macrophage markers ( HAM 56, CD 68, and EMR 1). Immunoreactive cells were quantified from the circular muscle layer. Key Results Significantly fewer ICC were detected in DG and IG tissues, but there were no differences in the numbers of cells immunoreactive for other markers between patient groups. There was a significant correlation between the number of CD 206+ cells and ICC in DG and DC patients, but not in C and IG and a significant correlation between i NOS + cells and ICC in the DC group, but not the other groups. CD 68 and HAM 56 reliably labeled the same cell populations, but EMR 1 labeled other cell types. Conclusions & Inferences Depletion of ICC and correlation with changes in CD 206+ cell numbers in DC and DG patients suggests that in humans, like mice, CD 206+ macrophages may play a cytoprotective role in diabetes. These findings may lead to novel therapeutic options, targeting alternatively activated macrophages.

Background: Allograft dysfunction due to presumed antibody‐mediated rejection (pAMR) is one of the most serious complications of heart transplantation. Combination therapies of high‐dose steroids, intravenous immune globulin, and/or therapeutic plasma exchange (TPE) are often used in this setting. Methods: We performed a 9‐year retrospective review of all episodes of pAMR treated with TPE at our institution. pAMR diagnosis was based on clinical and pathologic findings. Left ventricular ejection fraction (LVEF) was measured at baseline, prior to initiation of TPE, and during the course of treatment. Results: There were 42 patients with 47 episodes of pAMR treated with TPE. The majority of episodes were treated with three TPE; however, eight required only two TPE and five episodes required >3 TPE. All episodes of pAMR had LVEF measured before and after the series of TPEs. The mean pre‐TPE LVEF was 38% compared with a post‐therapy mean LVEF of 50% (P < 0.0001). In 16 episodes of pAMR, for which LVEF was measured following each apheresis, there was significant improvement of allograft function after the first TPE (pre‐TPE mean LVEF of 31% and post‐first TPE mean LVEF of 37%; P = 0.02). Incremental and significant improvement in allograft function continued following each TPE. Changes in human leukocyte antigen‐donor specific antibodies and fibrinogen did not correlate with ejection fraction response. Conclusions: The rapid improvement in allograft function in our patients is most likely due to TPE as other pharmacologic interventions have longer onset. TPE should be considered a first‐line intervention in the setting of pAMR. J. Clin. Apheresis 29:316–321 2014. © 2014 Wiley Periodicals, Inc.

Abstract Purpose: Clustering of neural autoantibodies in patients with paraneoplastic neurologic disorders may predict tumor type. A mathematical analysis of neural autoantibody clusters was performed in 78,889 patients undergoing evaluation for a suspected paraneoplastic autoimmune neurologic disorder. Tumor predictive autoantibody profiles were confirmed in sera from patients with histologically proven tonsillar cancer, thymoma, and lung cancer. Patients and Methods: Of note, 78,889 patient sera were tested for 15 defined neural autoantibodies (1.2 million tests). The observed and hypothesized frequencies of autoantibody clusters were compared and their tumor associations defined. A tumor validation study comprised serum from 368 patients with a variety of tumors (thymoma, lung, or tonsil). Results: Informative oncological associations included (i) thymoma in 85% of patients with muscle striational, acetylcholine receptor antibodies plus CRMP5 autoantibodies; (ii) lung carcinoma in 80% with both P/Q-type and N-type calcium channel antibodies plus SOX1-IgG; and (iii) in men, prostate carcinoma frequency more than doubled when striational and muscle AChR specificities were accompanied by ganglionic AChR antibody. In women, amphiphysin-IgG alone was associated commonly with breast carcinoma, but amphiphysin-IgG, coexisting with antineuronal nuclear autoantibody-type 1 or CRMP5-IgG, was associated with lung cancer (P &lt; 0.0001). In the validation cohorts, many tumor-associated profiles were encountered that matched the clusters identified in the screening study (e.g., 15% of thymoma patients had striational, acetylcholine receptor antibodies plus collapsin response-mediator protein-5 autoantibodies). Conclusions: Neural autoantibodies commonly coexist in specific clusters that are identifiable by comprehensive screening. Signature autoantibody clusters may predict a patient's cancer risk and type. Clin Cancer Res; 20(14); 3862–9. ©2014 AACR.

Abstract Aquaporin‐4 ( AQP 4) is a water channel protein that is most highly, but not exclusively, expressed in the central nervous system. In 2005 AQP 4 was shown to be the antigenic target of neuromyelitis optica‐immunoglobulin G ( NMO ‐IgG, or AQP 4‐IgG), an antibody found specifically in patients with NMO and in formes frustes of NMO , such as longitudinally extensive transverse myelitis (LETM) or optic neuritis (ON). This discovery facilitated the clinical, pathological, and radiological distinction of NMO and the spectrum of NMO ‐related disorders from classical multiple sclerosis. In addition to its use as a diagnostic tool, AQP 4‐IgG predicts a high risk of relapse in patients with a clinically isolated syndrome of either LETM or ON. As disability in NMO is attack‐related, early diagnosis and treatment are predicted to have a major effect on long‐term disability. Thus, the importance of sensitive and specific assays to detect AQP 4‐IgG cannot be overstated. Both academic institutions and commercial companies have developed assays to identify AQP 4‐IgG in patients' sera or cerebrospinal fluid. Both AQP 4 isoforms from different species have been used as the antigenic target in the form of frozen tissue sections in indirect immunofluorescence assays, partially purified protein for fluorescence immunoprecipitation assay, radioimmunoprecipitation assay or enzyme‐linked immunosorbent assay, or transfected into cells for cell based assays or flow cytometry. We carried out a systematic review of the literature reporting different methodologies used to identify AQP 4‐IgG, examine whether longitudinal AQP 4‐IgG titers predict relapses in seropositive patients, and attempt to establish a reasonable timeframe for retesting negative serum samples.