Q1 · MEDICINE
Article
Author: Tyner, Jeffrey W. ; Adam, Ammar ; Kurtz, Stephen E. ; Byth, Kate F. ; Lubinski, Tristan ; Lewis, Paula ; Gibbons, Francis D. ; Ioannidis, Stephanos ; Diebold, R. Bruce ; Gero, Thomas ; Johnstone, Ricky W. ; Gangl, Eric ; Saeh, Jamal C. ; Tavana, Omid ; Garnett, Mathew J. ; Cidado, Justin ; Schuller, Alwin ; Coker, Elizabeth A. ; McWeeney, Shannon K. ; Newbold, Andrea ; Lawson, Deborah ; Burke, Kathleen ; Tabatabai, Areya ; Gregory, Gareth P. ; McCoull, William ; Fawell, Stephen E. ; Wen, Shenghua ; Macintyre, Terry ; Varnes, Jeffrey ; Su, Nancy ; Davies, Barry R. ; Hennessy, Edward J. ; Criscione, Steven W. ; Balachander, Srividya B. ; Wild, Martin ; Secrist, J. Paul ; Jaaks, Patricia ; Zinda, Michael
Purpose::Targeting Bcl-2 family members upregulated in multiple cancers has emerged as an important area of cancer therapeutics. While venetoclax, a Bcl-2–selective inhibitor, has had success in the clinic, another family member, Bcl-xL, has also emerged as an important target and as a mechanism of resistance. Therefore, we developed a dual Bcl-2/Bcl-xL inhibitor that broadens the therapeutic activity while minimizing Bcl-xL–mediated thrombocytopenia.
Experimental Design::We used structure-based chemistry to design a small-molecule inhibitor of Bcl-2 and Bcl-xL and assessed the activity against in vitro cell lines, patient samples, and in vivo models. We applied pharmacokinetic/pharmacodynamic (PK/PD) modeling to integrate our understanding of on-target activity of the dual inhibitor in tumors and platelets across dose levels and over time.
Results::We discovered AZD4320, which has nanomolar affinity for Bcl-2 and Bcl-xL, and mechanistically drives cell death through the mitochondrial apoptotic pathway. AZD4320 demonstrates activity in both Bcl-2– and Bcl-xL–dependent hematologic cancer cell lines and enhanced activity in acute myeloid leukemia (AML) patient samples compared with the Bcl-2–selective agent venetoclax. A single intravenous bolus dose of AZD4320 induces tumor regression with transient thrombocytopenia, which recovers in less than a week, suggesting a clinical weekly schedule would enable targeting of Bcl-2/Bcl-xL–dependent tumors without incurring dose-limiting thrombocytopenia. AZD4320 demonstrates monotherapy activity in patient-derived AML and venetoclax-resistant xenograft models.
Conclusions::AZD4320 is a potent molecule with manageable thrombocytopenia risk to explore the utility of a dual Bcl-2/Bcl-xL inhibitor across a broad range of tumor types with dysregulation of Bcl-2 prosurvival proteins.