Abstract 3340: Intraoral administration of mitochondrial targeted GS-nitroxide (JP4-039) radioprotects the oral mucosa but not orthotopic tumors in Fancd2-/- mice

Proceedings: AACR 106th Annual Meeting 2015; April 18-22, 2015; Philadelphia, PA Fanconi Anemia (FA) patients are at risk for head and neck squamous cell carcinomas. Their normal tissue radiosensitivity often presents a challenge to deliver radiotherapy. Locally applied GS-nitroxide JP4-039 radioprotects the oral mucosa of Fancd2-/-(129/Sv) mice from single fraction or fractionated irradiation (Berhane et al, Radiation Research 182:35-49, 2014). We sought to prove that JP4-039 targets the mitochondria of the oral mucosal cells, and protects normal tissue in vivo, but does not prevent radiocontrolability of tumors. Fancd2+/+, Fancd2+/- and Fancd2-/- mice of a different background strain (C57BL/6), received intraoral flurochrome labelled bodipy-JP4-039 in F15 liposomes, were sacrificed 2 hr later and the oral mucosa removed sectioned, and stained with an antibody to mitochondrial protein TOM-20 and examined microscopically for co-localization of bodipy-JP4-039. Mitochondria were isolated from explanted oral mucosal cells and uptake of JP4-039 compared to non-mitochondrial targeted Tempo, measured using EPR. Fancd2+/+, Fancd2+/- and Fancd2-/- mice with orthotopic TC-1 murine squamous cell tumors were treated with JP-4-039/F15, then irradiated. Mitochondrial uptake in normal tissue but not tumors was demonstrated by co-localization of Bodipy-JP4-039 and mitochondrial protein TOM-20. EPR analysis of purified mitochondria from explanted oral cavity cells of Fancd2+/+ and Fancd2-/- mice treated with F15-JP4-039 showed a 15.6 and 19.1 fold increased uptake of nitroxide signal in JP4-039 treated mice, respectively, compared to Tempo uptake in mitochondria . There was no significant difference in tumor control between the JP4-039/F15 treated then irradiated compared to control irradiated mice, in any of the 3 genotypes: Fancd2+/+ group, p = 0.6851; Fancd2+/− group p = 0.7174 and p = 0.7559 in the Fancd2−/− group. JP4-039/F15 administration prior to either single fraction 28 Gy or prior to each fraction of fractionated head and neck irradiation (8 Gy x 4) showed significant normal tissue protection (decreased ulceration) but not tumor radioprotection. Irradiation reduced tumor volume in mice of all genotypes with no detectable effect of JP4-039/F15. Specifically, with wild type Fancd2+/+ mice after 28 Gy, there was no radioprotective effect of JP4-039/F15 on tumor regrowth (p = 0.7520). Tumor bearing Fancd2−/− (p = 0.1843) and Fancd2+/− mice also showed normal tissue but not tumor protection (p = 0.4106 and p = 0.1843, respectively). The data support use of normal mucosal radioprotective JP4-039/F15 during radiotherapy of FA patients with head and neck cancer. Citation Format: Michael W. Epperly, Ashwin Shinde, Hebist Berhane, Byung Han Rhieu, Ronny Kalash, Karen Xu, Darcy Franicola, Xichen Zhang, Tracy Dixon, Donna Shields, Hong Wang, Peter Wipf, Kalindi Parmar, Eva Guinan, Valerian Kagan, Yulia Tyurina, Robert L. Ferris, Song Li, Joel S. Greenberger. Intraoral administration of mitochondrial targeted GS-nitroxide (JP4-039) radioprotects the oral mucosa but not orthotopic tumors in Fancd2-/- mice. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3340. doi:10.1158/1538-7445.AM2015-3340