MCL-1 inhibitors - where are we now (2019)?

Introduction: Myeloid cell leukemia-1 (MCL-1) is an anti-apoptotic member of the B-cell lymphoma-2 (BCL-2) family of proteins that regulates apoptosis. Elevated levels of MCL-1 contribute to tumorigenesis and resistance, not only to conventional chemotherapies but also to targeted therapies, including the BCL-2 selective inhibitor venetoclax. Accordingly, researchers in both the pharmaceutical industry and academia have been actively seeking MCL-1 inhibitors in the quest for new anti-cancer drugs. Areas covered: This review covers the patent literature on the discovery and development of small-molecule inhibitors of MCL-1 since 2017. Expert opinion: Pharmacologic inhibition of MCL-1's oncogenic activity has certainly come of age with the discovery of numerous inhibitors spanning a variety of chemotypes that selectively inhibit MCL-1 in the picomolar range and with on-target cell activity. Furthermore, seminal research by Servier has demonstrated for the first time that MCL-1 inhibition is tolerable in animal models of cancer, paving the way for the six Phase 1 clinical trials that are currently underway for hematological malignancies, among other cancers. After more than a decade of research, the hurdles and obstacles are mostly behind us, and uncovering the therapeutic impact of disrupting the protein-protein interactions of MCL-1 in humans is imminent.