Abstract 5211: Targeting Neddylation synergistically augments the activity of cisplatin in head and neck cancer models to yield long-term survival by modulating key DNA damage and redox pathways

Head and neck cancer is a broad term for neoplasms of the epithelial lining of the anatomical sites of the upper aerodigestive tract. Very few novel therapeutics have been developed for the treatment of advanced head and neck cancer with cisplatin continuing to be a key standard of care agent. Innovative and more effective therapeutic strategies are urgently needed. The inappropriate loss of several NEDD8-cullin-RING ubiquitin ligase (CRL) targets has been linked to cancer progression and drug resistance. Our data show that overexpression of NEDD8 activating enzyme (NAE), a key proximal regulator of the NEDDylation cascade, is correlated with inferior survival in head and neck cancers suggesting that this pathway may be a promising new therapeutic target. We hypothesized that disrupting NEDDylation with the first-in-class NAE inhibitor pevonedistat (MLN4924, PEV) would be an effective new approach for the treatment of head and neck cancers. Initial testing demonstrated that PEV potently impaired the NEDDylation cascade as evidenced by decreased NEDDylated cullins and upregulation of the CRL target cell cycle inhibitors, p21 and p27. In addition, PEV induced a dramatic G2 cell cycle arrest, polyploidy, and activation of the DNA damage response. PEV treatment also potently decreased cell viability and induced apoptosis in a panel of head and neck cancer cell lines with diverse genetic features. Given the potent DNA damage-related aspects of PEV9s mechanism of action, we hypothesized that it would be a rational combination partner for standard cisplatin therapy. Consistent with this hypothesis, co-treatment with PEV and cisplatin promoted synergistic levels of DNA damage as measured by comet assay, an accumulation of gamma-H2AX, and quantification of DNA fragmentation. The combination also cooperated to promote redox alterations that were necessary for apoptosis induction and linked to the DNA damaging effects of both drugs. Importantly, synergistic anticancer activity was observed in cell lines from multiple anatomical sites, suggesting that this combination has broad efficacy across many subtypes of head and neck cancer. To further evaluate the therapeutic benefit of the PEV and cisplatin combination, we determined its safety and efficacy in a head and neck cancer xenograft model. Consistent with our in vitro data, the combination significantly decreased tumor proliferation, induced apoptosis, and augmented DNA damage in vivo. While both PEV and cisplatin displayed significant activity as monotherapies, combination treatment resulted in a dramatic decrease in tumor burden and also led to long-term animal survival in every treated animal (10/10 mice remained disease-free at day 100). Importantly, the PEV and cisplatin combination was therapeutically selective and very well tolerated in mice. Our collective data provide a strong rationale for the clinical investigation of NAE inhibition as a novel strategy to augment cisplatin efficacy in patients with head and neck cancer. Citation Format: Trace Jones, Claudia Espitia, Jennifer Carew, Steffan T. Nawrocki. Targeting Neddylation synergistically augments the activity of cisplatin in head and neck cancer models to yield long-term survival by modulating key DNA damage and redox pathways [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5211.