Structure–Activity Relationship of the Epothilones and the First In Vivo Comparison with Paclitaxel

Ahead! Epothilone B (1, RMe) displayed better antitumor activity than paclitaxel (Taxol), as shown by in vivo studies with resistant mouse tumor models. The "acyl sector" C1C8 in the epothilones is very sensitive to modification. The other two sectors (see structure on the right) can be varied to a certain extent; however, none of the analogues examined thus far have surpassed the parent compound.