The present invention relates to compositions and methods using an isolated chimeric molecule, wherein the isolated chimeric molecule comprises an
antibody, one or more
albumin motifs, optional
peptide linkers, and two or more
antibiotics or
cytotoxic drug molecules conjugated to the unpaired
cysteine residues, optionally through linkers. In one embodiment, each of the said
albumin motifs in the isolated chimeric molecule contains 2 or more unpaired
cysteine residues. In another embodiment, the said
antibody in the isolated chimeric molecule targets antigens on
cancer cells or
drug-
resistant bacteria. In another embodiment, the
cancer cells have upregulated macropinocytosis. In another embodiment, the
cancer cells contain one or more mutations in their RAS family genes. The compositions of the invention are used to treat
drug-resistant bacterial infections and cancers, preferably the ones with upregulated macropinocytosis, and the ones containing one or more mutations in their RAS family genes.