CDK2/CDK4

Class

first-in-class, highly potent and selective oral small-molecule degrader that simultaneously degrades CDK2 and CDK4 while sparing CDK1, CDK6, CDK7, and CDK9

Pathway

targeted degradation of CDK2 and CDK4 disrupts cell-cycle progression in tumors, including those resistant to approved CDK4/6 inhibitors; designed to reduce the GI/hematologic toxicity seen with pan-CDK4/6 inhibition

CDK2 and CDK4 are cyclin-dependent kinases that drive the transition of a cell from a resting state into DNA synthesis and division. CDK4 partners with cyclin D to begin phosphorylating the retinoblastoma protein (Rb), a brake on cell division; CDK2, working with cyclin E, completes this phosphorylation and commits the cell to divide. Many cancers depend on this pathway for uncontrolled growth, which is why CDK4/6 inhibition became a validated strategy in oncology. However, tumors often develop resistance by amplifying cyclin E or otherwise activating CDK2 to bypass CDK4/6 blockade, and existing inhibitors also affect CDK6 broadly in bone marrow, causing low blood counts. This mechanism uses a degrader rather than a catalytic inhibitor: the molecule eliminates the CDK2 and CDK4 proteins themselves, aiming to block both entry points into cell division while deliberately sparing CDK1 (needed for normal cell division machinery), CDK6 (implicated in marrow toxicity), and the transcriptional kinases CDK7 and CDK9 (broadly essential for gene expression). The intended result is a therapy effective in tumors that have escaped conventional CDK4/6 inhibition, with a narrower toxicity profile than pan-CDK approaches.