title: A pilot phase II study of valproic acid for treatment of low-grade neuroendocrine carcinoma.
abstract: BACKGROUND
  Notch1 has been shown to be a tumor suppressor in neuroendocrine tumors (NETs). Previous in vitro studies in NET cell lines have also suggested that valproic acid (VPA), a histone deacetylase inhibitor, can induce Notch1 and that Notch1 activation correlates with a decrease in tumor markers for NETs. Thus, this study aimed to evaluate the role of VPA in treating NETs and to determine whether VPA induced the Notch signaling pathway signaling in vivo.
  
  
  METHODS
  Eight patients with low-grade NETs (carcinoid and pancreatic) were treated with 500 mg of oral VPA twice a day with dosing adjusted to maintain a goal VPA level between 50 and 100 μg/mL. All patients were followed for 12 months or until disease progression.
  
  
  RESULTS
  Notch1 signaling was absent in all tumors prior to treatment and was upregulated with VPA. One patient had an unconfirmed partial response and was noted to have a 40-fold increase in Notch1 mRNA levels. Four patients had stable disease as best response. Tumor markers improved in 5 out of 7 patients. Overall, treatment with VPA was well tolerated.
  
  
  CONCLUSIONS
  . VPA activates Notch1 signaling in vivo and may have a role in treating low-grade NETs.
authors.affiliation: D.O., M.S., University of Wisconsin Hospital and Clinics, 600 Highland Avenue, Madison, Wisconsin 53792, USA. tmohammed@uwhealth.org.
authors.forename: Tabraiz A
authors.initials: TA
authors.lastname: Mohammed
authors.forename: Kyle D
authors.initials: KD
authors.lastname: Holen
authors.forename: Renata
authors.initials: R
authors.lastname: Jaskula-Sztul
authors.forename: Daniel
authors.initials: D
authors.lastname: Mulkerin
authors.forename: Sam J
authors.initials: SJ
authors.lastname: Lubner
authors.forename: William R
authors.initials: WR
authors.lastname: Schelman
authors.forename: Jens
authors.initials: J
authors.lastname: Eickhoff
authors.forename: Herbert
authors.initials: H
authors.lastname: Chen
authors.forename: Noelle K
authors.initials: NK
authors.lastname: Loconte
mesh_terms: D000368:Aged; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D014408:Biomarkers, Tumor; D018278:Carcinoma, Neuroendocrine / Q000188:drug therapy*; D004305:Dose-Response Relationship, Drug; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D056572:Histone Deacetylase Inhibitors / Q000627:therapeutic use; D006801:Humans; D008297:Male; D008875:Middle Aged; D010190:Pancreatic Neoplasms / Q000188:drug therapy*; D010865:Pilot Projects; D051881:Receptor, Notch1 / Q000187:drug effects / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D014635:Valproic Acid / Q000627:therapeutic use*
chemical_list: D000970:Antineoplastic Agents; D014408:Biomarkers, Tumor; D056572:Histone Deacetylase Inhibitors; C497761:NOTCH1 protein, human; D051881:Receptor, Notch1; D014635:Valproic Acid