Farnesyltransferase inhibitors in myelodysplastic syndrome.
The farnesyltransferase inhibitors (FTIs) are in active clinical development in a variety of human malignancies. The most promising activity to date has been demonstrated in patients with hematologic malignancies, in particular acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS). In patients with MDS, two nonpeptidomimetic agents, tipifarnib (Zarnestra, Johnson & Johnson, New Brunswick, NJ) and lonafarnib (Sarasar, Schering-Plough, Kenilworth, NJ) have been the most extensively studied. In both phase I and phase II trials, tipifarnib has demonstrated significant efficacy, with overall response rates of 30% and complete remissions in about 15%. Dose-limiting adverse effects have been primarily myelosuppression, although fatigue, neurotoxicity, and occasional renal dysfunction have required dose reductions. Lonafarnib in patients with MDS has also resulted in clinical responses in approximately 30%, including significant improvements in platelet counts. Lonafarnib has been associated primarily with diarrhea and other gastrointestinal toxicity, anorexia, and nausea, which has limited its efficacy. Clinical response correlation with documentation of inhibition of farnesyltransferase and/or evidence of decreased farnesylation of downstream protein targets has not been demonstrated with either agent. In addition, the presence of an activating Ras mutation has not predicted response to therapy with FTIs in MDS and AML. Despite this lack of evidence, significant clinical efficacy of the FTIs has been observed in MDS, on a par with the efficacy of currently available chemotherapeutic agents, leading to further development of this new class of drugs in MDS and AML.
Feldman
E J
EJ
Weill Medical College of Cornell University, 525 East 68th Street, New York, NY 10021, USA. ejf2001@med.cornell.edu
D000328:Adult; D000368:Aged; D000970:Antineoplastic Agents / Q000627:therapeutic use; D001855:Bone Marrow Diseases / Q000139:chemically induced; D017321:Clinical Trials, Phase I as Topic; D017322:Clinical Trials, Phase II as Topic; D018450:Disease Progression; D051231:Farnesyltranstransferase / Q000037:antagonists & inhibitors*; D005767:Gastrointestinal Diseases / Q000139:chemically induced; D011905:Genes, ras; D019337:Hematologic Neoplasms / Q000188:drug therapy; D006801:Humans; D008875:Middle Aged; D009190:Myelodysplastic Syndromes / Q000188:drug therapy* / Q000201:enzymology / Q000235:genetics; D010880:Piperidines / Q000009:adverse effects / Q000494:pharmacology / Q000627:therapeutic use*; D054876:Prenylation / Q000187:drug effects; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D011725:Pyridines / Q000009:adverse effects / Q000494:pharmacology / Q000627:therapeutic use*; D015363:Quinolones / Q000009:adverse effects / Q000494:pharmacology / Q000627:therapeutic use*; D016896:Treatment Outcome; D003986:Dibenzocycloheptenes
D000970:Antineoplastic Agents; D051231:Farnesyltranstransferase; D010880:Piperidines; D011725:Pyridines; D015363:Quinolones; C115354:lonafarnib; D003986:Dibenzocycloheptenes; C402769:tipifarnib