Deregulation of the MYC oncoprotein drives tumorigenesis in most–if not all–cancers and generally correlates with poor prognosis, suggesting that its inhibition would be a useful therapeutic strategy. Indeed, we have shown that Myc inhibition displays extraordinary therapeutic benefit in various transgenic mouse models of cancer (i.e., skin, lung, pancreatic cancer and glioma), without eliciting resistance to therapy, and causes only mild, well-tolerated and reversible side effects in normal tissues. For these studies we employed a dominant negative inhibitor of Myc, called Omomyc, which is an effective inhibitor of Myc transactivation function both in vitro and in vivo. Omomyc has so far been utilized exclusively as a transgene, as a successful proof of principle whose application was believed to be solely limited to gene therapy. Here, though, we show that the purified Omomyc polypeptide itself spontaneously transduces into cancer cells and effectively interferes with MYC transcription, abrogating cell cycle and promoting apoptosis in different cancer cells, independently of their mutational profile. Efficacy of the Omomyc polypeptide in two complementary murine models of non-small cell lung cancer (NSCLC) establishes its therapeutic potential through both direct tissue delivery (intranasal) and systemic intravenous administration, providing for the first time evidence that the Omomyc polypeptide is an effective MYC inhibitor worthy of clinical development.

Citation Format: Marie-Eve Beaulieu, Toni Jauset, Daniel Massó-Vallés, Sandra Martínez-Martín, Peter Rahl, Löika Maltais, Mariano F. Zacarias-Fluck, Sílvia Casacuberta-Serra, Erika Serrano del Pozo, Christopher Fiore, Laia Foradada, Virginia Castillo Cano, Matthew Guenther, Eduardo Romero Sanza, Marta Oteo, Cynthia Tremblay Tremblay, Génesis Martín, Danny Letourneau, Martin Montagne, Miguel Ángel Morcillo Alonso, Jonathan R. Whitfield, Pierre Lavigne, Laura Soucek. Omomyc-based cell-penetrating peptides: From proof of concept to a clinically viable anti-Myc therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3956.