Abstract C190: Potent and selective inhibition of CDK7 by novel covalent inhibitors

Cyclin-dependent kinase 7 (CDK7) is an important constituent of the cellular transcriptional machinery, where it phosphorylates the C-terminal domain (CTD) of RNAP polymerase II (RNAPII). Because many tumor types are critically dependent on transcription for maintenance of their oncogenic state, pharmacological modulation of CDK7 kinase activity is considered as an approach to treat cancer. Multiple series of CDK7 inhibitors were identified by iterative medicinal chemistry efforts and SAR based approach. Early compounds were optimized towards attaining good physicochemical properties, high potency, good selectivity and desirable pharmacokinetic profile to achieve anti-tumor activity. We have identified compounds from two distinct chemical series that are highly potent in inhibiting CDK7 in biochemical assays. These inhibitors demonstrate time-dependent inhibition of CDK7 indicating covalent nature of binding. The compounds showed potent anti-proliferative activity in cell lines derived from various tumor types and this was accompanied by CDK7 modulation in cells as monitored by pS5RNAPII levels. They have excellent drug-like characteristics including solubility, permeability, metabolic stability and good oral bioavailability. In a broad panel of kinases (332 kinase), selected compounds from both series showed good selectivity profile. Tolerability and efficacy studies are ongoing with selected early leads to test their impact on tumor growth inhibition in xenograft models. We have identified novel and selective CDK7 covalent inhibitors from two series with desirable drug-like properties, which are being evauated for anti-tumor activity in xenograft models. Citation Format: Ramulu Poddutoori, Leena K. Satyam, Girish Daginakatte, Subhendu Mukherjee, Sivapriya Marappan, Sreevalsam Gopinath, Raghuveer Ramachandra, Anirudha Lakshminarasimhan, Manoj Pothuganti, Shilpa Nayak, Nandish C, Chandranath Naik, Ravindra MV, Madhu Dabbeeru, Thomas Antony, Chetan Pandit, Murali Ramachandra, Shekar Chelur, Susanta Samajdar. Potent and selective inhibition of CDK7 by novel covalent inhibitors. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr C190.