Compounds for the treatment of cancer

A compound of Formula (III):

• or a pharmaceutically acceptable salt thereof, wherein
• R1a is selected from the group consisting of —H, —OH, and —F;
• R1b is selected from the group consisting of —H, —OH, and —F, wherein at least one of R1a and R1b is —H;
• R4a is selected from the group consisting of —H, —OH, and —F;
• R4b is selected from the group consisting of —H, —OH, and —F, wherein at least one of R4a and R4b is —H;
• P1 and P2 each independently has an S or R stereochemical configuration;
• Z is —O— or —NH—;
• X1a and X2a are the same or different and are independently selected from ═O or ═S;
• X1b and X2b are the same or different and are independently selected from —OR5 and —SR5;
• wherein R5 is selected from the group consisting of —H, —C1-6alkyl, —C(O)C1-6alkyl, and —CH2OC(O)OC1-6alkyl;
• L1 in formula (III) is four, five, or six carbons in length, and is
• wherein indicates a singe bond, a double bond, or a triple bond and wherein (i) either 0 or 1 occurrence of in L1 indicates a triple bond;
• or (ii) 0, 1, or 2 occurrences of in L1 indicates a double bond, wherein geometry about each double bond is cis or trans;
• and (iii) wherein when 1 occurrence of in L1 indicates a triple bond, 0 occurrences of in L1 indicates a double bond;
• and (iv) wherein, when 2 occurrences of in L1 indicate a double bond, those double bonds are either adjacent bonds or alternating bonds;
• wherein X10, X11, X12, X13, X14, and X15 are independently selected from a bond, —CH2—, or —CH—, wherein the —CH2— or —CH— is unsubstituted or substituted by (i) —OH, (ii) —F, (iii) —Cl, (iv) —NH2, or (v) -D, and when X10 or X15 is a bond, that bond is not a double bond or triple bond;
• and wherein any two adjacent members of the group including X10, X11, X12, X13, X14, and X15 may optionally form, with additional atoms, a C3 cycloalkyl or a C3 heterocycloalkyl, said C3 heterocycloalkyl including an N or O atom;
• wherein B1 and B2 are independently selected from:
• where the bonds at points q and r on B1 and B2 are attached at points q and r on Formula (III).