Quinazolinone-based anticancer agents were designed, decorated with functional groups from a 2-methoxyestradiol-based microtubule disruptor series, incorporating the aryl sulfamate motif of steroid sulfatase (STS) inhibitors. The steroidal AB-ring system was mimicked, favoring conformations with an N-2 substituent occupying D-ring space. Evaluation against breast and prostate tumor cell lines identified 7bwith DU-145 antiproliferative activity (GI50300 nM). A preliminary structure–activity relationship afforded compounds (e.g., 7jGI5050 nM) with activity exceeding that of the parent. Both 7band 7jinhibit tubulin assembly in vitro and colchicine binding, and 7jwas successfully co-crystallized with the αβ-tubulin heterodimer as the first of its class, its sulfamate group interacting positively at the colchicine binding site. Microtubule destabilization by 7jis likely achieved by preventing the curved-to-straight conformational transition in αβ-tubulin. Quinazolinone sulfamates surprisingly showed weak STS inhibition. Preliminary in vivo studies in a multiple myeloma xenograft model for 7bshowed oral activity, confirming the promise of this template.