INTRODUCTION: 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. PATIENTS AND 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. CONCLUSION: . VPA activates Notch1 signaling in vivo and may have a role in treating low-grade NETs.
INTRODUCTION: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. PATIENTS AND 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. CONCLUSION: . VPA activates Notch1 signaling in vivo and may have a role in treating low-grade NETs.
Authors: P Therasse; S G Arbuck; E A Eisenhauer; J Wanders; R S Kaplan; L Rubinstein; J Verweij; M Van Glabbeke; A T van Oosterom; M C Christian; S G Gwyther Journal: J Natl Cancer Inst Date: 2000-02-02 Impact factor: 13.506
Authors: Matthew H Kulke; Haesook Kim; Jeffrey W Clark; Peter C Enzinger; Thomas J Lynch; Jeffrey A Morgan; Michele Vincitore; Ann Michelini; Charles S Fuchs Journal: Cancer Date: 2004-09-01 Impact factor: 6.860
Authors: T Delaunoit; M Van den Eynde; I Borbath; P Demetter; G Demolin; P Pattyn; S Pauwels; M Peeters; G Roeyen; E Van Cutsem; Ph Van Hootegem; J L Van Laethem; C Verslype; A Hendlisz Journal: Acta Gastroenterol Belg Date: 2009 Jan-Mar Impact factor: 1.316