Oxabicycloheptanes for treatment of secondary acute myeloid leukemia

A method for treating secondary acute myeloid leukemia (sAML) in a patient comprising administering a PP2A inhibitor in combination with an anti-cancer agent so as to thereby treat sAML;

• wherein the PP2a inhibitor has the structure:
• wherein:
• bond α is present or absent;
• R1 and R2 together are ═O;
• R3 is OH, O−, OR9, O(CH2)1-6R9, SH, S−, or SR9, wherein R9 is H, alkyl, alkenyl, alkynyl or aryl;
• R4 is
• where X is O, S, NR10, N+HR10 or N+R10R10, where each R10 is independently H, alkyl, alkenyl, alkynyl, aryl,
• —CH2CN, —CH2CO2R11, or —CH2COR11, wherein each R11 is independently H, alkyl, alkenyl or alkynyl;
• R5 and R6 taken together are ═O;
• R7 and R8 are each H,
• or a salt, zwitterion, or ester thereof.

A method of enhancing cytotoxicity of an anti-cancer agent in a patient afflicted with sAML comprising administering to the patient a PP2A inhibitor having the structure:

• wherein:
• bond α is present or absent;
• R1 and R2 together are ═O;
• R3 is OH, O−, OR9, O(CH2)1-6R9, SH, S−, or SR9, wherein R9 is H, alkyl, alkenyl, alkynyl or aryl;
• R4 is
• where X is O, S, NR10, N+HR10 or N+R10R10, where each R10 is independently H, alkyl, alkenyl, alkynyl, aryl,
• —CH2CN, —CH2CO2R11, or —CH2COR11, wherein each R11 is independently H, alkyl, alkenyl or alkynyl;
• R5 and R6 taken together are ═O;
• R7 and R8 are each H,
• or a salt, zwitterion, or ester thereof.