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Intravenous Administration Approved for Azacitidine
With IV administration, the dosing for Vidaza remains the same as the previously approved subcutaneous (SC) administration at 75 mg/m2 daily, for seven days, every four weeks. Since this approval is for an alternative administration of the existing formulation, Pharmion will begin promoting this IV route of administration immediately.
"We are extremely pleased to receive an approval to administer Vidaza via an IV infusion, as this now provides two convenient delivery routes for physicians to meet their MDS treatment goals," said Patrick J. Mahaffy, Pharmion's president and CEO. "We believe that offering this kind of flexibility for treatment administration within the label will be very important to physicians and their patients."
The FDA approval of IV administration of Vidaza was based on existing clinical data from the original NDA, an uncontrolled Phase II study and a bioavailability study, as well as additional data from an in-use stability and compatibility study and a pharmacokinetic modeling study recently completed by Pharmion.
On May 19, 2004, Vidaza became the first drug approved by the FDA for the treatment of patients with Myelodysplastic Syndromes (MDS). The FDA approved Vidaza, the first in a new class of drugs called demethylation agents, for treatment of all five MDS subtypes, which include both low-risk and high-risk patients. These subtypes include: refractory anemia (RA) or refractory anemia with ringed sideroblasts (RARS) if accompanied by neutropenia or thrombocytopenia or requiring transfusions; refractory anemia with excess blasts (RAEB), refractory anemia with excess blasts in transformation (RAEB-T), and chronic myelomonocytic leukemia (CMMoL).
Vidaza is believed to exert its antineoplastic effects by causing hypomethylation of DNA and direct cytotoxicity on abnormal hematopoietic cells in the bone marrow. The concentration of azacitidine required for maximum inhibition of DNA methylation in vitro does not cause major suppression of DNA synthesis. Hypomethylation may restore normal function to genes that are critical for differentiation and proliferation. The cytotoxic effects of azacitidine cause the death of rapidly dividing cells, including cancer cells that are no longer responsive to normal growth control mechanisms. Non-proliferating cells are relatively insensitive to Vidaza.
Azacitidine is the first of a new class of anti-cancer compounds called epigenetic therapies. DNA methylation and histone deacetylation are two of the more studied epigenetic regulators of gene expression. Epigenetics refers to changes in the regulation of gene expression. Epigenetic changes can silence gene expression and, unlike DNA mutations, may be reversed by targeting the enzymes involved. The silencing of key cell cycle control genes and tumor suppressor genes through these two mechanisms of epigenetic regulation has been demonstrated in vitro and in vivo in hematological malignancies and in solid tumors. These key growth control genes can be re-expressed in cancer cells when DNA hypermethylation is reversed by Vidaza and/or inappropriate histone deacetylation is inhibited by MGCD0103. The epigenetic approach to cancer therapy is that rather than using molecules that kill both normal and tumor cells, the silenced genes are reactivated through targeted epigenetic therapy, re-establishing the cancer cell's natural mechanisms to control abnormal growth.
Important Safety Information
Vidaza is contraindicated in patients with a known hypersensitivity to azacitidine or mannitol and in patients with advanced malignant hepatic tumors.
In clinical studies, the most commonly occurring adverse reactions by SC route were nausea (70.5%), anemia (69.5%), thrombocytopenia (65.5%), vomiting (54.1%), pyrexia (51.8%), leukopenia (48.2%), diarrhea (36.4%), fatigue (35.9%), injection site erythema (35.0%), constipation (33.6%), neutropenia (32.3%) and ecchymosis (30.5%). Other adverse reactions included dizziness (18.6%), chest pain (16.4%), febrile neutropenia (16.4%), myalgia (15.9%), injection site reaction (13.6%), aggravated fatigue (12.7%) and malaise (10.9%). The most common adverse reactions by IV route also included petechiae (45.8%), rigors (35.4%), weakness (35.4%) and hypokalemia (31.3%).
Because treatment with Vidaza is associated with neutropenia and thrombocytopenia, complete blood counts should be performed as needed to monitor response and toxicity, but at a minimum, prior to each dosing cycle.
Because azacitidine is potentially hepatotoxic in patients with severe pre-existing hepatic impairment, caution is needed in patients with liver disease. In addition, azacitidine and its metabolites are substantially excreted by the kidneys and the risk of toxic reactions to this drug may be greater in patients with impaired renal function. Because elderly patients are more likely to have decreased renal function, it may be useful to monitor renal function.
Vidaza may cause fetal harm. While receiving treatment with Vidaza, women of childbearing potential should avoid becoming pregnant, and men should avoid fathering a child. In addition, women treated with Vidaza should not nurse.