A compound having anticancer activity, or a pharmaceutically acceptable salt thereof is provided. Used is a compound represented by the following formula (I) or a pharmaceutically acceptable salt thereof:
(wherein, L
1
and L
2
are the same or different and each represents a group represented by one formula selected from the group consisting of formulas (A) to (F), and S represents a group represented by one formula selected from the group consisting of formulas (S1) to (S18)).
The present invention provides a BET (protein) degrader, specifically a BET degrader containing a compound represented by formula (I) or a pharmaceutically acceptable salt thereof:
wherein L1 and L2 are the same or different and each represents a small molecular ligand for BET protein, and S represents a group represented by a formula selected from the group consisting of formulas (SI) to (S18).