A method for predicting whether a cancer patient will respond to treatment with a histone deacetylase-6 (HDAC6) inhibitor comprising the steps of: a) measuring the expression level of the following genes: pterin-4 alpha-carbinolamine dehydratase/dimerization cofactor of hepatocyte nuclear factor 1 alpha (PCBD1); protein phosphatase 2, regulatory subunit B, gamma isoform (PPP2R2C); neural precursor cell expressed, developmentally downregulated 4 (NEDD4); prolyl 4-hydroxylase, alpha polypeptide II (P4HA2); SLC2A4 regulator (SLC2A4RG); sulfatase 2 (SULF2); lysosomal protein transmembrane 4 alpha (LAPTM4A); 3'-phosphoadenosine 5'-phosphosulfate synthase 2 (PAPSS2); aldo-keto reductase family 1, member C1 (dihydrodiol dehydrogenase 1; 20-alpha (3-alpha)-hydroxysteroid dehydrogenase) (AKR1C1); protein tyrosine phosphatase, non-receptor type 12 (PTPN12); DCN1, defective in cullin neddylation 1, domain containing 4 (S. cerevisiae) (DCUN1D4); ras-related C3 botulinum toxin substrate 2; acyl-Coexzyme A dehydrogenase, C-4 to C-112 straight chain (ACADM); Rho GTPase activating protein 4 (ARHGAP4); ATPase type 13A1 (ATP13A1); chemokine receptor 7; coronin 7 (CORO7); CXXC finger 4 (CXXC4); differentially expressed in FDCP 6 homolog; KRI1 homolog; limb region 1 homolog (LMBR1L); leukotriene B4 receptor (LTB4R); RAD54-like 2 (RAD54L2); chromosome X open reading frame 21 (CXorf21); SREBF chaperone (SCAP); selectin L (SELL); splicing factor 3a, subunit 2 (SF3A2); Lyrm7 homolog (LYRM7); O-linked N-acetylglucosamine transferase; tubulin, alpha 3c (TUBA3C); tubulin, alpha 3d (TUBA3D); KH-type splicing regulatory protein (KHSRP); DEAH (Asp-Glu-Ala-His) box polypeptide 30; APEX nuclease (apurinic/apyrimidinic endonuclease) 2 (APEX2); and abhydrolase domain containing 14A (ABHD14A) in a biological sample from the cancer patient; and for said genes: b) correlating a low expression level, as compared to a normalized gene expression level of the gene, of PCBD1, PPP2R2C, NEDD4, P4HA2, SLC2A4RG, SULF2, LAPTM4A, PAPSS2, AKR1C1, PTPN12, and DCUN1D4 as an indication that the patient will respond to such treatment; or correlating a high expression level, as compared to a normalized gene expression level of the gene, of RAC2, ACADM, ARHGAP4, ATP13A1, CCR7, CORO7, CXXC4, DEF6, KRI1, LMBR1L, LTB4R, RAD54L2, CXorf21, SCAP, SELL, SF3A2, LYRM7, OGT, TUBA3C, TUBA3D, KHSRP, DHX30, APEX2, and ABHD14A as an indication that the patient will respond to such treatment. a) measuring the expression level of the following genes: pterin-4 alpha-carbinolamine dehydratase/dimerization cofactor of hepatocyte nuclear factor 1 alpha (PCBD1); protein phosphatase 2, regulatory subunit B, gamma isoform (PPP2R2C); neural precursor cell expressed, developmentally downregulated 4 (NEDD4); prolyl 4-hydroxylase, alpha polypeptide II (P4HA2); SLC2A4 regulator (SLC2A4RG); sulfatase 2 (SULF2); lysosomal protein transmembrane 4 alpha (LAPTM4A); 3'-phosphoadenosine 5'-phosphosulfate synthase 2 (PAPSS2); aldo-keto reductase family 1, member C1 (dihydrodiol dehydrogenase 1; 20-alpha (3-alpha)-hydroxysteroid dehydrogenase) (AKR1C1); protein tyrosine phosphatase, non-receptor type 12 (PTPN12); DCN1, defective in cullin neddylation 1, domain containing 4 (S. cerevisiae) (DCUN1D4); ras-related C3 botulinum toxin substrate 2; acyl-Coexzyme A dehydrogenase, C-4 to C-112 straight chain (ACADM); Rho GTPase activating protein 4 (ARHGAP4); ATPase type 13A1 (ATP13A1); chemokine receptor 7; coronin 7 (CORO7); CXXC finger 4 (CXXC4); differentially expressed in FDCP 6 homolog; KRI1 homolog; limb region 1 homolog (LMBR1L); leukotriene B4 receptor (LTB4R); RAD54-like 2 (RAD54L2); chromosome X open reading frame 21 (CXorf21); SREBF chaperone (SCAP); selectin L (SELL); splicing factor 3a, subunit 2 (SF3A2); Lyrm7 homolog (LYRM7); O-linked N-acetylglucosamine transferase; tubulin, alpha 3c (TUBA3C); tubulin, alpha 3d (TUBA3D); KH-type splicing regulatory protein (KHSRP); DEAH (Asp-Glu-Ala-His) box polypeptide 30; APEX nuclease (apurinic/apyrimidinic endonuclease) 2 (APEX2); and abhydrolase domain containing 14A (ABHD14A) in a biological sample from the cancer patient; and for said genes: b) correlating a low expression level, as compared to a normalized gene expression level of the gene, of PCBD1, PPP2R2C, NEDD4, P4HA2, SLC2A4RG, SULF2, LAPTM4A, PAPSS2, AKR1C1, PTPN12, and DCUN1D4 as an indication that the patient will respond to such treatment; or correlating a high expression level, as compared to a normalized gene expression level of the gene, of RAC2, ACADM, ARHGAP4, ATP13A1, CCR7, CORO7, CXXC4, DEF6, KRI1, LMBR1L, LTB4R, RAD54L2, CXorf21, SCAP, SELL, SF3A2, LYRM7, OGT, TUBA3C, TUBA3D, KHSRP, DHX30, APEX2, and ABHD14A as an indication that the patient will respond to such treatment. b) correlating a low expression level, as compared to a normalized gene expression level of the gene, of PCBD1, PPP2R2C, NEDD4, P4HA2, SLC2A4RG, SULF2, LAPTM4A, PAPSS2, AKR1C1, PTPN12, and DCUN1D4 as an indication that the patient will respond to such treatment; or correlating a high expression level, as compared to a normalized gene expression level of the gene, of RAC2, ACADM, ARHGAP4, ATP13A1, CCR7, CORO7, CXXC4, DEF6, KRI1, LMBR1L, LTB4R, RAD54L2, CXorf21, SCAP, SELL, SF3A2, LYRM7, OGT, TUBA3C, TUBA3D, KHSRP, DHX30, APEX2, and ABHD14A as an indication that the patient will respond to such treatment.