The identification of three distinct but structurally related classes of microbial-derived spliceosome modulators has provided an exciting opportunity for the development of mechanistically new cancer treatments. A team at UC San Diego has undertaken a SAR study on the spliceosome modulator FD-895 that focused on improving compound stability, while retaining potent antiproliferative and splicing activity. This led to the identification of a more potent and stable analog, (17S)-FD-895 (1), and a less active but extremely stable cyclopropane analog 2, which is currently undergoing preclinical evaluation. These analogs will serve as templates for next generation spliceosome modulating anticancer drugs.