Discovery of an <i>In Vivo</i> Chemical Probe for BCL6 Inhibition by Optimization of Tricyclic Quinolinones
Alice C. Harnden, Owen A. Davis, Gary Box, Angela Hayes, Louise D. Johnson, Alan T. Henley, Alexis K. de Haven Brandon, Melanie Valenti, Kwai-Ming J. Cheung, Alfie Brennan, Rosemary Huckvale, Olivier A. Pierrat, Rachel Talbot, Michael D. Bright, Hafize Aysin Akpinar, Daniel S. J. Miller, Dalia Tarantino, Sharon Gowan, Selby de Klerk, Craig McAndrew, Yann‐Vaï Le Bihan, Mirco Meniconi, Rosemary Burke, Vladimir Kirkin, Rob L. M. van Montfort, Florence I. Raynaud, Olivia W. Rossanese, Benjamin R. Bellenie, Swen Hoelder
Abstract
High Resolution Image Download MS PowerPoint Slide B-cell lymphoma 6 (BCL6) is a transcriptional repressor and oncogenic driver of diffuse large B-cell lymphoma (DLBCL). Here, we report the optimization of our previously reported tricyclic quinolinone series for the inhibition of BCL6. We sought to improve the cellular potency and in vivo exposure of the non-degrading isomer, CCT373567, of our recently published degrader, CCT373566 . The major limitation of our inhibitors was their high topological polar surface areas (TPSA), leading to increased efflux ratios. Reducing the molecular weight allowed us to remove polarity and decrease TPSA without considerably reducing solubility. Careful optimization of these properties, as guided by pharmacokinetic studies, led to the discovery of CCT374705, a potent inhibitor of BCL6 with a good in vivo profile. Modest in vivo efficacy was achieved in a lymphoma xenograft mouse model after oral dosing.