title: Phase I study of the histone deacetylase inhibitor entinostat in combination with 13-cis retinoic acid in patients with solid tumours.
abstract: BACKGROUND
  Preclinical studies suggest that histone deacetylase (HDAC) inhibitors may restore tumour sensitivity to retinoids. The objective of this study was to determine the safety, tolerability, and the pharmacokinetic (PK)/pharmacodynamic (PD) profiles of the HDAC inhibitor entinostat in combination with 13-cis retinoic acid (CRA) in patients with solid tumours.
  
  
  METHODS
  Patients with advanced solid tumours were treated with entinostat orally once weekly and with CRA orally twice daily × 3 weeks every 4 weeks. The starting dose for entinostat was 4 mg m(-2) with a fixed dose of CRA at 1 mg kg(-1) per day. Entinostat dose was escalated by 1 mg m(-2) increments. Pharmacokinetic concentrations of entinostat and CRA were determined by LC/MS/MS. Western blot analysis of peripheral blood mononuclear cells and tumour samples were performed to evaluate target inhibition.
  
  
  RESULTS
  A total of 19 patients were enroled. The maximum tolerated dose (MTD) was exceeded at the entinostat 5 mg m(-2) dose level (G3 hyponatremia, neutropenia, and anaemia). Fatigue (G1 or G2) was a common side effect. Entinostat exhibited substantial variability in clearance (147%) and exposure. CRA trough concentrations were consistent with prior reports. No objective responses were observed, however, prolonged stable disease occurred in patients with prostate, pancreatic, and kidney cancer. Data further showed increased tumour histone acetylation and decreased phosphorylated ERK protein expression.
  
  
  CONCLUSIONS
  The combination of entinostat with CRA was reasonably well tolerated. The recommended phase II doses are entinostat 4 mg m(-2) once weekly and CRA 1 mg kg(-1) per day. Although no tumour responses were seen, further evaluation of this combination is warranted.
authors: The Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, 1650 Orleans Street, CRB1 Room 1M52, Baltimore, MD 21231, USA. Roberto.Pili@RoswellPark.org
authors: R
authors: R
authors: Pili
authors: B
authors: B
authors: Salumbides
authors: M
authors: M
authors: Zhao
authors: S
authors: S
authors: Altiok
authors: D
authors: D
authors: Qian
authors: J
authors: J
authors: Zwiebel
authors: M A
authors: MA
authors: Carducci
authors: M A
authors: MA
authors: Rudek
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000008:administration & dosage / Q000009:adverse effects / Q000493:pharmacokinetics / Q000627:therapeutic use*; D001549:Benzamides / Q000008:administration & dosage; D015153:Blotting, Western; D002853:Chromatography, Liquid; D005260:Female; D056572:Histone Deacetylase Inhibitors / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D006801:Humans; D015474:Isotretinoin / Q000008:administration & dosage; D008297:Male; D020714:Maximum Tolerated Dose; D008875:Middle Aged; D009369:Neoplasms / Q000188:drug therapy* / Q000378:metabolism; D011725:Pyridines / Q000008:administration & dosage; D053719:Tandem Mass Spectrometry; D016896:Treatment Outcome
chemical_list: D001549:Benzamides; D056572:Histone Deacetylase Inhibitors; D011725:Pyridines; C118739:entinostat; D015474:Isotretinoin