Bis-octahydrophenanthrene carboxamides and protein conjugates thereof

A compound of Formula A

• or a pharmaceutically acceptable salt, or stereoisomeric form thereof, wherein
• L is a linker or X—Y—Z, wherein
• X is —NH— or —O—;
• Y is an enzymatically cleavable moiety;
• a self-immolative group;
• an acid-labile moiety comprising an alkoxamine, ketoxamine, carbonate, or phosphonate;
• PEGn;
• a sugar moiety comprising a glucuronide;
• and/or an enhancement group comprising a cyclodextrin and/or an alkyl, heteroalkyl, alkylenyl, or heteroalkylenyl sulfonic acid;
• and
• Z is a binding agent linker (BL) wherein Z is covalently bound to BA;
• BA is an antibody or antigen binding fragment thereof;
• k ranges from about one to about eight, representing an average number of units of a payload conjugated to BA;
• each of Q1 and Q2 is independently —CH2, C(O)—, —C(H)(OH)—, or —C(OH)2—;
• W is —CH2—, —N(H)—, or —O—;
• R is independently hydrogen, —OH, C1-6 alkyl, or —OP (O)(OR6)(OH);
• and
• each R6 is, independently in each instance, hydrogen, an amino acid residue, a peptide, or alkyl;
• and
• each R7 is independently halo, C1-6 alkyl, C1-6 alkoxy, —CN, O-glucose, O-amino acid residue, or O-PEGn, wherein each n is an integer from zero to three.