title: In-vitro synergism of m-TOR inhibitors, statins, and classical chemotherapy: potential implications in acute leukemia.
abstract: Classical chemotherapy has an active, but limited, role in acute leukemia with relapse common in adult patients. Recent evidence has implicated signal transduction pathways in leukemic progression and also in resistance to cytotoxic therapy. We have used a short-term, in-vitro incubation assay with cytotoxic analysis by MTT, confirmed by histone-associated DNA fragmentation, to evaluate both classical and nonclassical combinations of drugs. Isobologram median effect analysis, confirmed by curve shift analysis, was used to identify synergy and antagonism. Fluvastatin, a prenylation inhibitor, demonstrates global enhancement of the effects of classical agents in both AML-193 and KG-1 cell lines. Similarly, the m-TOR inhibitors, RAD-001 (everolimus) and rapamycin, also cause time-dependent global enhancement of cytotoxic agents. At clinically achievable combinations, RAD-001 perturbs the AKT pathway in vitro. The unique combination of fluvastatin and an m-TOR inhibitor was synergistic in both cell lines. These effects were independent of whether or not human plasma was used in the assay system. These studies suggest several novel combinations of agents that need to be evaluated in the management of leukemia.
authors.affiliation: Experimental Therapeutics Section, Don Monti Division of Oncology, Monter Cancer Center, Lake Success, NY 11042, USA.
authors.forename: Anthony
authors.initials: A
authors.lastname: Calabro
authors.forename: Julia
authors.initials: J
authors.lastname: Tai
authors.forename: Steven L
authors.initials: SL
authors.lastname: Allen
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Budman
mesh_terms: D000208:Acute Disease; D000970:Antineoplastic Agents / Q000494:pharmacology*; D045744:Cell Line, Tumor; D004357:Drug Synergism; D000068338:Everolimus; D005229:Fatty Acids, Monounsaturated / Q000494:pharmacology*; D000077340:Fluvastatin; D006801:Humans; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000494:pharmacology*; D007211:Indoles / Q000494:pharmacology*; D007938:Leukemia / Q000188:drug therapy* / Q000473:pathology; D011494:Protein Kinases / Q000187:drug effects*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D020123:Sirolimus / Q000031:analogs & derivatives* / Q000494:pharmacology*; D058570:TOR Serine-Threonine Kinases
chemical_list: D000970:Antineoplastic Agents; D005229:Fatty Acids, Monounsaturated; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D007211:Indoles; D000077340:Fluvastatin; D000068338:Everolimus; D011494:Protein Kinases; C546842:MTOR protein, human; D051057:Proto-Oncogene Proteins c-akt; D058570:TOR Serine-Threonine Kinases; D020123:Sirolimus