A fatty acid synthase inhibitor for use in a method of treating a paclitaxel-resistant tumor or cancer in a subject, the method comprising administering to the subject in need thereof a therapeutically effective amount of a fatty acid synthase inhibitor and a therapeutically effective amount of paclitaxel or Nab-paclitaxel; wherein the fatty acid synthase inhibitor is a compound having the structure of: (a) Formula: or (b) Formula: or (c) Formula: or a pharmaceutically acceptable salt thereof, wherein: R 1 is H, -CN, halogen, C 1 -C 4 straight or branched alkyl, -O-(C 3 -C 5 cycloalkyl), -O-(C 1 -C 4 straight or branched alkyl) wherein: C 3 -C 5 cycloalkyl optionally includes an oxygen or nitrogen heteroatom; and when R 1 is not H, -CN or halogen, it is optionally substituted with one or more halogens; each R 2 is independently hydrogen, halogen or C 1 -C 4 straight or branched alkyl; R 3 is H, -OH, or halogen; R 21 is H, halogen, C 1 -C 4 straight or branched alkyl, C 3 -C 5 cycloalkyl wherein the C 3 -C 5 cycloalkyl optionally includes an oxygen or nitrogen heteroatom; R 22 is H, halogen, or C 1 -C 2 alkyl; R 24 is H, C 1 -C 4 straight or branched alkyl, -(C 1 -C 4 alkyl) t -OH, -(C 1 -C 4 alky)) t O t -(C 3 -C 5 cycloalkyl), or -(C 1 -C 4 alkyl) t -O-(C 1 -C 4 straight or branched alkyl) wherein: t is 0 or 1; the C 3 -C 5 cycloalkyl optionally includes an oxygen or nitrogen heteroatom; L 1 is CR 23 or N; L 2 is CR 23 or N; at least one of L 1 or L 2 is N; and R 23 is H or C 1 -C 4 straight or branched alkyl. (a) Formula: or (b) Formula: or (c) Formula: or a pharmaceutically acceptable salt thereof, wherein: R 1 is H, -CN, halogen, C 1 -C 4 straight or branched alkyl, -O-(C 3 -C 5 cycloalkyl), -O-(C 1 -C 4 straight or branched alkyl) wherein: C 3 -C 5 cycloalkyl optionally includes an oxygen or nitrogen heteroatom; and when R 1 is not H, -CN or halogen, it is optionally substituted with one or more halogens; each R 2 is independently hydrogen, halogen or C 1 -C 4 straight or branched alkyl; R 3 is H, -OH, or halogen; R 21 is H, halogen, C 1 -C 4 straight or branched alkyl, C 3 -C 5 cycloalkyl wherein the C 3 -C 5 cycloalkyl optionally includes an oxygen or nitrogen heteroatom; R 22 is H, halogen, or C 1 -C 2 alkyl; R 24 is H, C 1 -C 4 straight or branched alkyl, -(C 1 -C 4 alkyl) t -OH, -(C 1 -C 4 alky)) t O t -(C 3 -C 5 cycloalkyl), or -(C 1 -C 4 alkyl) t -O-(C 1 -C 4 straight or branched alkyl) wherein: t is 0 or 1; the C 3 -C 5 cycloalkyl optionally includes an oxygen or nitrogen heteroatom; L 1 is CR 23 or N; L 2 is CR 23 or N; at least one of L 1 or L 2 is N; and R 23 is H or C 1 -C 4 straight or branched alkyl. R 1 is H, -CN, halogen, C 1 -C 4 straight or branched alkyl, -O-(C 3 -C 5 cycloalkyl), -O-(C 1 -C 4 straight or branched alkyl) wherein: C 3 -C 5 cycloalkyl optionally includes an oxygen or nitrogen heteroatom; and when R 1 is not H, -CN or halogen, it is optionally substituted with one or more halogens; each R 2 is independently hydrogen, halogen or C 1 -C 4 straight or branched alkyl; R 3 is H, -OH, or halogen; R 21 is H, halogen, C 1 -C 4 straight or branched alkyl, C 3 -C 5 cycloalkyl wherein the C 3 -C 5 cycloalkyl optionally includes an oxygen or nitrogen heteroatom; R 22 is H, halogen, or C 1 -C 2 alkyl; R 24 is H, C 1 -C 4 straight or branched alkyl, -(C 1 -C 4 alkyl) t -OH, -(C 1 -C 4 alky)) t O t -(C 3 -C 5 cycloalkyl), or -(C 1 -C 4 alkyl) t -O-(C 1 -C 4 straight or branched alkyl) wherein: t is 0 or 1; the C 3 -C 5 cycloalkyl optionally includes an oxygen or nitrogen heteroatom; L 1 is CR 23 or N; L 2 is CR 23 or N; at least one of L 1 or L 2 is N; and R 23 is H or C 1 -C 4 straight or branched alkyl.