Compounds comprising cleavable linker and uses thereof

A conjugate of Formula (I′):

• (D-L)n-(CB)cb (I′)
• or a pharmaceutically acceptable salt thereof,
• wherein:
• CB is a targeting moiety;
• cb and n are each independently integers having a value of 1 to about 20;
• each D-L independently is a group having the structure of Formula (I″):
• each Q is independently an active agent linked to L′ by a heteroatom;
• Z′ is a linking group;
• L′ is a spacer moiety attached to the SO2 via a heteroatom selected from O, S, and N, and is selected such that cleavage of the bond between L′ and SO2 promotes cleavage of the bond between L′ and Q to release the active agent;
• X is —O—, —C(Rb)2—, or —N(Rc)—;
• Ar is aryl, heteroaryl, cycloalkyl, or heterocycloalkyl;
• Y′ is —(CRb2)yN(Ra)—, —(CRb2)yO—, or —(CRb2)yS—, positioned such that the N, O, or S atom is attached to TG if y is 1;
• X and Y′ are positioned on adjacent atoms of Ar;
• TG is a triggering group that, when activated, generates an N, O, or S atom capable of reacting with the SO2 to displace (Q)q-(L′)w and form a 5-6-membered ring including X—SO2 and the intervening atoms of Ar;
• q is an integer having a value from 1 to about 20;
• w, x, and y are each independently an integer having a value of 0 or 1;
• each Ra and Rc is independently hydrogen or lower alkyl;
• and
• each Rb is independently hydrogen or lower alkyl;
• or
• two Rb, together with the atom to which they are attached, form a 3-5-membered ring;
• provided that when w is 0, q is 1.