Reactive Oxygen Species Mediates the Synergistic Activity of Fenretinide Combined with the Microtubule Inhibitor ABT-751 against Multidrug-Resistant Recurrent Neuroblastoma Xenografts

Mol Cancer Ther. 2016 Nov;15(11):2653-2664. doi: 10.1158/1535-7163.MCT-16-0156. Epub 2016 Aug 16.


ABT-751 is a colchicine-binding site microtubule inhibitor. Fenretinide (4-HPR) is a synthetic retinoid. Both agents have shown activity against neuroblastoma in laboratory models and clinical trials. We investigated the antitumor activity of 4-HPR + the microtubule-targeting agents ABT-751, vincristine, paclitaxel, vinorelbine, or colchicine in laboratory models of recurrent neuroblastoma. Drug cytotoxicity was assessed in vitro by a fluorescence-based assay (DIMSCAN) and in subcutaneous xenografts in nu/nu mice. Reactive oxygen species levels (ROS), apoptosis, and mitochondrial depolarization were measured by flow cytometry; cytochrome c release and proapoptotic proteins were measured by immunoblotting. 4-HPR + ABT-751 showed modest additive or synergistic cytotoxicity, mitochondrial membrane depolarization, cytochrome c release, and caspase activation compared with single agents in vitro; synergism was inhibited by antioxidants (ascorbic acid, α-tocopherol). 4-HPR + ABT-751 was highly active against four xenograft models, achieving multiple maintained complete responses. The median event-free survival (days) for xenografts from 4 patients combined was control = 28, 4-HPR = 49, ABT-751 = 77, and 4-HPR + ABT-751 > 150 (P < 0.001). Apoptosis (terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling, TUNEL) was significantly higher in 4-HPR + ABT-751-treated tumors than with single agents (P < 0.01) and was inhibited by ascorbic acid and α-tocopherol (P < 0.01), indicating that ROS from 4-HPR enhanced the activity of ABT-751. 4-HPR also enhanced the activity against neuroblastoma xenografts of vincristine or paclitaxel, but the latter combinations were less active than 4-HPR + ABT-751. Our data support clinical evaluation of 4-HPR combined with ABT-751 in recurrent and refractory neuroblastoma. Mol Cancer Ther; 15(11); 2653-64. ©2016 AACR.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antineoplastic Agents / pharmacology*
  • Antioxidants / pharmacology
  • Apoptosis / drug effects
  • Caspases / metabolism
  • Cell Line, Tumor
  • Cell Survival / drug effects
  • Cytochromes c / metabolism
  • Disease Models, Animal
  • Drug Resistance, Multiple*
  • Drug Resistance, Neoplasm*
  • Fenretinide / pharmacology*
  • Humans
  • Membrane Potential, Mitochondrial / drug effects
  • Mice
  • Neoplasm Recurrence, Local
  • Neuroblastoma / drug therapy
  • Neuroblastoma / metabolism*
  • Neuroblastoma / mortality
  • Neuroblastoma / pathology*
  • Reactive Oxygen Species / metabolism*
  • Sulfonamides / pharmacology*
  • Tumor Burden / drug effects
  • Xenograft Model Antitumor Assays


  • ABT751
  • Antineoplastic Agents
  • Antioxidants
  • Reactive Oxygen Species
  • Sulfonamides
  • Fenretinide
  • Cytochromes c
  • Caspases