Pf-06840003: A Highly Selective Ido-1 Inhibitor That Shows Good In Vivo Efficacy In Combination With Immune Checkpoint Inhibitors

Tumors use tryptophan-catabolizing enzymes such as Indoleamine 2,3-dioxygenase-1 (IDO-1) to induce an immunosuppressive microenvironment. IDO-1 expression is upregulated in many cancers and described to be a resistance mechanism to immune checkpoint therapies. IDO-1 is induced in response to inflammatory stimuli such as IFN-a and promotes immune tolerance through the catabolism of tryptophan and accumulation of tryptophan catabolites including kynurenine. IDO-1 activity leads to effector T-cell anergy and enhanced Treg function through upregulation of FoxP3. As such, IDO1 is a nexus for the induction of key immunosuppressive mechanisms and represents an important immunotherapeutic target in oncology. We have identified and characterized a new IDO-1 inhibitor. PF-06840003 is a highly selective orally bioavailable IDO-1 inhibitor. PF-06840003 reversed IDO-1-induced T-cell anergy in vitro. In vivo, PF-06840003 reduced intratumoral kynurenine levels in mice by u003e80% and inhibited tumor growth in multiple preclinical syngeneic models in mice, in combination with immune checkpoint inhibitors. PF-0684003 has favorable predicted human pharmacokinetic properties, including a predicted t1/2 of 16-19 hours. These studies highlight the strong potential of PF-06840003 as a clinical candidate in Immuno-Oncology. Citation Format: Joseph Tumang, Bruno Gomes, Martin Wythes, Stefano Crosignani, Patrick Bingham, Pauline Bottemanne, Helene Cannelle, Sandra Cauwenberghs, Jenny Chaplin, Deepak Dalvie, Sofie Denies, Coraline De Maeseneire, Peter Folger, Kim Frederix, Jie Guo, James Hardwick, Ken Hook, Katti Jessen, Erick Kindt, Marie-Claire Letellier, Kai-Hsin Liao, Wenlin Li, Karen Maegley, Reece Marillier, Nichol Miller, Brion Murray, Romain Pirson, Julie Preillon, Virginie Rabolli, Chad Ray, Stephanie Scales, Jay Srirangam, Jim Solowiej, Nicole Streiner, Vince Torti, Konstantinos Tsaparikos, Paolo Vicini, Gregory Driessens, Manfred Kraus. PF-06840003: a highly selective IDO-1 inhibitor that shows good in vivo efficacy in combination with immune checkpoint inhibitors. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4863.