RP-6306 is a first-in-class small molecule inhibitor of PKMYT1.

Using our proprietary, CRISPR-based SNIPRx discovery platform, we identified PKMYT1 as a strong hit in a CCNE1-overexpression SL screen. PKMYT1 is a kinase that phosphorylates CDK1, thereby holding the cyclin B-CDK1 complex in an inactive state until the cell is ready to enter mitosis.

RP-6306 is being developed as a highly potent and selective PKMYT1 inhibitor that preferentially kills tumor cells overexpressing CCNE1 and was shown to inhibit the growth of a broad range of CCNE1-amplified tumors in xenograft/PDX preclinical models, both as a single agent and in combination therapy settings.

RP-6306 has a favorable pre-clinical PK profile as well as low potential for drug-drug interactions. Application of our STEP² genome-wide chemical screen has identified other gene alterations beyond CCNE1 amplification that are uniquely targetable by RP-6306, including tumors that have loss of FBXW7 function, a cell-cycle regulator that has been implicated as a key genetic driver in a broad range of cancers, and represent a further area of unmet medical need.