DESCRIPTION

VUMON® (teniposide injection) (also commonly known as VM-26), is supplied as a sterile nonpyrogenic solution in a nonaqueous medium intended for dilution with a suitable parenteral vehicle prior to intravenous infusion. VUMON is available in 50 mg (5 mL) ampules. Each mL contains 10 mg teniposide, 30 mg benzyl alcohol, 60 mg N,N-dimethylacetamide, 500 mg purified Cremophor® EL (polyoxyethylated castor oil)*, and 42.7% (v/v) dehydrated alcohol. The pH of the clear solution is adjusted to approximately 5 with maleic acid.

*Cremophor® EL is the registered trademark of BASF Aktiengesellschaft.
 Cremophor® EL is further purified by a Bristol-Myers Squibb Company proprietary process before use.

Teniposide is a semisynthetic derivative of podophyllotoxin. The chemical name for teniposide is 4′-demethylepipodophyllotoxin 9-[4,6-O-(R)-2-thenylidene-β-D-glucopyranoside]. Teniposide differs from etoposide, another podophyllotoxin derivative, by the substitution of a thenylidene group on the glucopyranoside ring.

Teniposide has the following structural formula:

Teniposide is a white to off-white crystalline powder with the empirical formula C32H32O13S and a molecular weight of 656.66. It is a lipophilic compound with a partition coefficient value (octanol/water) of approximately 100. Teniposide is insoluble in water and ether. It is slightly soluble in methanol and very soluble in acetone and dimethylformamide.

CLINICAL PHARMACOLOGY

Teniposide is a phase-specific cytotoxic drug, acting in the late S or early G2 phase of the cell cycle, thus preventing cells from entering mitosis.

Teniposide causes dose-dependent single- and double-stranded breaks in DNA and DNA-protein cross-links. The mechanism of action appears to be related to the inhibition of type II topoisomerase activity since teniposide does not intercalate into DNA or bind strongly to DNA. The cytotoxic effects of teniposide are related to the relative number of double-stranded DNA breaks produced in cells, which are a reflection of the stabilization of a topoisomerase II-DNA intermediate.

Teniposide has a broad spectrum of in vivo antitumor activity against murine tumors, including hematologic malignancies and various solid tumors. Notably, teniposide is active against sublines of certain murine leukemias with acquired resistance to cisplatin, doxorubicin, amsacrine, daunorubicin, mitoxantrone, or vincristine.

Plasma drug levels declined biexponentially following intravenous infusion (155 mg/m2 over 1 to 2.5 hours) of VUMON given to 8 children (4-11 years old) with newly diagnosed acute lymphoblastic leukemia (ALL). The observed average pharmacokinetic parameters and associated coefficients of variation (CV%) based on a two-compartmental model analysis of the data are as follows:

There appears to be some association between an increase in serum alkaline phosphatase or gamma glutamyl-transpeptidase and a decrease in plasma clearance of teniposide. Therefore, caution should be exercised if VUMON is to be administered to patients with hepatic dysfunction.

In adults, at doses of 100 to 333 mg/m2/day, plasma levels increased linearly with dose. Drug accumulation in adult patients did not occur after daily administration of VUMON for 3 days. In pediatric patients, maximum plasma concentrations (Cmax) after infusions of 137 to 203 mg/m2 over a period of 1 to 2 hours exceeded 40 mcg/mL; by 20 to 24 hours after infusion plasma levels were generally <2 mcg/mL.

Renal clearance of parent teniposide accounts for about 10% of total body clearance. In adults, after intravenous administration of 10 mg/kg or 67 mg/m2 of tritium-labeled teniposide, 44% of the radiolabel was recovered in urine (parent drug and metabolites) within 120 hours after dosing. From 4% to 12% of a dose is excreted in urine as parent drug. Fecal excretion of radioactivity within 72 hours after dosing accounted for 0% to 10% of the dose.

Mean steady-state volumes of distribution range from 8 to 44 L/m2 for adults and 3 to 11 L/m2 for children. The blood-brain barrier appears to limit diffusion of teniposide into the brain, although in a study in patients with brain tumors, CSF levels of teniposide were higher than CSF levels reported in other studies of patients who did not have brain tumors.

Teniposide is highly protein bound. In vitro plasma protein binding of teniposide is >99%. The high affinity of teniposide for plasma proteins may be an important factor in limiting distribution of drug within the body. Steady-state volume of distribution of the drug increases with a decrease in plasma albumin levels. Therefore, careful monitoring of children with hypoalbuminemia is indicated during therapy. Levels of teniposide in saliva, CSF, and malignant ascites fluid are low relative to simultaneously measured plasma levels.

The pharmacokinetic characteristics of teniposide differ from those of etoposide, another podophyllotoxin. Teniposide is more extensively bound to plasma proteins and its cellular uptake is greater. Teniposide also has a lower systemic clearance, a longer elimination half-life, and is excreted in the urine as parent drug to a lesser extent than etoposide.

In a study at St. Jude Children's Research Hospital (SJCRH), 9 children with acute lymphocytic leukemia (ALL) failing induction therapy with a cytarabine-containing regimen, were treated with VUMON plus cytarabine. Three of these patients were induced into complete remission with durations of remission of 30 weeks, 59 weeks, and 13 years. In another study at SJCRH, 16 children with ALL refractory to vincristine/prednisone-containing regimens were treated with VUMON plus vincristine and prednisone. Three of these patients were induced into complete remission with durations of remission of 5.5, 37, and 73 weeks. In these 2 studies, patients served as their own control based on the premise that long-term complete remissions could not be achieved by re-treatment with drugs to which they had previously failed to respond.

INDICATIONS AND USAGE

VUMON (teniposide injection), in combination with other approved anticancer agents, is indicated for induction therapy in patients with refractory childhood acute lymphoblastic leukemia.

CONTRAINDICATIONS

VUMON is generally contraindicated in patients who have demonstrated a previous hypersensitivity to teniposide and/or Cremophor® EL (polyoxyethylated castor oil).

WARNINGS

VUMON is a potent drug and should be used only by physicians experienced in the administration of cancer chemotherapeutic drugs. Blood counts, as well as renal and hepatic function tests, should be carefully monitored prior to and during therapy.

Patients being treated with VUMON (teniposide injection) should be observed frequently for myelosuppression both during and after therapy. Dose-limiting bone marrow suppression is the most significant toxicity associated with VUMON therapy. Therefore, the following studies should be obtained at the start of therapy and prior to each subsequent dose of VUMON: hemoglobin, white blood cell count and differential, and platelet count. If necessary, repeat bone marrow examination should be performed prior to the decision to continue therapy in the setting of severe myelosuppression.

Physicians should be aware of the possible occurrence of a hypersensitivity reaction variably manifested by chills, fever, urticaria, tachycardia, bronchospasm, dyspnea, hypertension or hypotension, and facial flushing. This reaction may occur with the first dose of VUMON and may be life threatening if not treated promptly with antihistamines, corticosteroids, epinephrine, intravenous fluids, and other supportive measures as clinically indicated. The exact cause of these reactions is unknown. They may be due to the Cremophor® EL (polyoxyethylated castor oil) component of the vehicle or to teniposide itself. Patients who have experienced prior hypersensitivity reactions to VUMON are at risk for recurrence of symptoms and should only be re-treated with VUMON if the antileukemic benefit already demonstrated clearly outweighs the risk of a probable hypersensitivity reaction for that patient. When a decision is made to re-treat a patient with VUMON in spite of an earlier hypersensitivity reaction, the patient should be pretreated with corticosteroids and antihistamines and receive careful clinical observation during and after VUMON infusion. In the clinical experience with VUMON at SJCRH and the National Cancer Institute (NCI), re-treatment of patients with prior hypersensitivity reactions has been accomplished using measures described above. To date, there is no evidence to suggest cross-sensitization between VUMON and VePesid®.

One episode of sudden death, attributed to probable arrhythmia and intractable hypotension, has been reported in an elderly patient receiving VUMON combination therapy for a non-leukemic malignancy. (See ADVERSE REACTIONS.) Patients receiving VUMON treatment should be under continuous observation for at least the first 60 minutes following the start of the infusion and at frequent intervals thereafter. If symptoms or signs of anaphylaxis occur, the infusion should be stopped immediately, followed by the administration of epinephrine, corticosteroids, antihistamines, pressor agents, or volume expanders at the discretion of the physician. An aqueous solution of epinephrine 1:1000 and a source of oxygen should be available at the bedside.

For parenteral administration, VUMON should be given only by slow intravenous infusion (lasting at least 30 to 60 minutes) since hypotension has been reported as a possible side effect of rapid intravenous injection, perhaps due to a direct effect of Cremophor® EL. If clinically significant hypotension develops, the VUMON infusion should be discontinued. The blood pressure usually normalizes within hours in response to cessation of the infusion and administration of fluids or other supportive therapy as appropriate. If the infusion is restarted, a slower administration rate should be used and the patient should be carefully monitored.

Acute central nervous system depression, hypotension, and metabolic acidosis have been observed in patients receiving investigational infusions of high-dose VUMON who were pretreated with antiemetic drugs. The depressant effects of the antiemetic agents and the alcohol content of the VUMON formulation may place patients receiving higher than recommended doses of VUMON at risk for central nervous system depression.

Pregnancy

Pregnancy Category D

VUMON may cause fetal harm when administered to a pregnant woman. VUMON has been shown to be teratogenic and embryotoxic in laboratory animals. In pregnant rats, intravenous administration of VUMON, 0.1 to 3 mg/kg (0.6-18 mg/m2), every second day from day 6 to day 16 post coitum caused dose-related embryotoxicity and teratogenicity. Major anomalies included spinal and rib defects, deformed extremities, anophthalmia, and celosomia.

There are no adequate and well-controlled studies in pregnant women. If VUMON is used during pregnancy, or if the patient becomes pregnant while receiving this drug, the patient should be apprised of the potential hazard to the fetus. Women of childbearing potential should be advised to avoid becoming pregnant during therapy with VUMON.

PRECAUTIONS

General

In all instances where the use of VUMON is considered for chemotherapy, the physi