Myelodysplastic syndromes (MDS), a collection of disorders in which the bone marrow does not produce enough mature cells, has received a lot of attention in recent years despite the fact that it affects only about five in 100,000 people. This is due in part to the Food & Drug Administration's approval of several new molecular entities used in its treatment, including azacitidine (Vidaza, Pharmion) in 2004 and lenalidomide (Revlimid, Celgene) in 2005. And just last month the agency approved a third drug, decitabine injection (Dacogen, MGI Pharma).
"Decitabine is closely related to the hypomethylation compound azacitidine," explained Sachin Shah, Pharm.D., BCOP, clinical pharmacist specialist in hematology/oncology at the Texas Tech University Health Sciences Center School of Pharmacy in Dallas. "It exerts its anticancer effects after phosphorylation and incorporation into DNA and inhibition of DNA methyltransferase." This promotes hypomethylation of DNA and cellular differentiation or apoptosis. "Decitabine-induced hypomethylation in cancer cells may restore normal gene function," Shah said.
Dosage adjustment or delay of treatment should be based on hematology laboratory values. According to MGI Pharma, a hema-tologic recovery is defined as ANC 1,000 cells/microliter and platelets 50,000/microliter. If these values do not recover within six weeks from the last decitabine treatment, the next cycle of treatment should be delayed or reduced.
According to Shah, who is also assistant professor of pharmacy practice in the adult medicine division at Texas Tech, the advantage to this drug is that it is approved for several subtypes of the dis-order, including secondary MDS-chemotherapy-induced disease. "A disadvantage is that it may require hospitalization of the patient in order to administer it." In contrast, he pointed out, most other common treatment options such as growth factors, azacitidine, and lenalidomide can be administered subcutaneously or orally.
Decitabine is classified as Pregnancy Category D and may cause harm to pregnant women. Women of childbearing age should be advised not to become pregnant during treatment, and men should not father a child while receiving decitabine and for two months afterward due to the effect of the drug on male fertility. The most common adverse reactions during clinical trials included neutropenia, thrombocytopenia, anemia, fatigue, pyrexia, nausea, cough, constipation, diarrhea, petechiae, and hyperglycemia.
TIPS TO REMEMBER Dacogen