Oprelvekin - Chemical, Pharmacological and Marketing Data

Chemical, Pharmacological and Marketing Data

IL-11 is a member of a family of human growth factors and is being produced in the bone marrow of healthy adults. Synonyms are:

• AGIF
• Adipogenesis inhibitory factor
• Interleukin-11 precursor.

Oprelvekin is produced in Escherichia coli (E. coli) by recombinant DNA technology. The protein has a molecular mass of approximately 19,000 daltons, and is non-glycosylated. The polypeptide is 177 amino acids in length (the natural IL-11 has 178). This alteration has not resulted in measurable differences in bioactivity either in vitro or in vivo.

The primary hematopoietic activity of Neumega is stimulation of megakaryocytopoiesis and thrombopoiesis. In mice and nonhuman primate studies Neumega has shown potent thrombopoietic activity in compromised hematopoiesis, including moderately to severely myelosuppressed animals. In these studies, Neumega improved platelet nadirs and accelerated platelet recoveries compared to controls.

In animal studies Oprelvekin also has non-hematopoetic activities. This includes the regulation of intestinal epithelium growth (enhanced healing of gastrointestinal lesions), the inhibition of adipogenesis, the induction of acute phase protein synthesis (e.g., fibrinogen), and inhibition of macrophageal released pro-inflammatory cytokines. However, pathologic changes, some also seen in humans, have been noticed:

• papilledema
• fibrosis of tendons and joint capsules
• periostal thickening and
• embryotoxicity (see under pregnancy).

In preclinical human trials mature megakaryocytes which develop during in vivo treatment with Neumega were ultrastructurally, morphologically, and functionally normal. They also showed a normal life span.

In a study in which a single 50 µg/kg subcutaneous dose was administered to eighteen healthy men, the peak serum concentration (Cmax) of 17.4 ± 5.4 ng/mL was reached at 3.2 ± 2.4 h (Tmax) following dosing. The terminal half-life was 6.9 ± 1.7 h. In a second study in which single 75 µg/kg subcutaneous and intravenous doses were administered to twenty-four healthy subjects, the pharmacokinetic profiles were similar between men and women. The absolute bioavailability of Neumega was >80%. In a study in which multiple, subcutaneous doses of both 25 and 50 µg/kg were administered to cancer patients receiving chemotherapy, Neumega did not accumulate and clearance of Neumega was not altered following multiple doses. Pediatric cancer patients treated with aggressive chemotherapy showed similar pharmakinetic characteristics.

In humans treated with Oprelvekin on a daily base a twofold increase in fibrinogen levels occurred. Healthy volunteers displayed an increase in von-Willebrand-factor (vWf) activity. Isolated molecules formed under Oprelvekin were found to have exact the same multimere structure as the 'normal' factor and were therefore fully functioning. These increases in coagulation factors may contribute to the development of stroke (see under side-effects), but a precise association cannot be made at this stage.

In a variety of clinical studies upon which FDA approval is based, Neumega showed effectivity in reducing thrombocytopenia in oncologic patients treated with myelosuppressant chemotherapeutic drugs as measured by significantly decreased need of platelet transfusions.

Neumega is manufactured and sold by Wyeth. The drug is formulated in single-use vials containing 5 mg of oprelvekin (specific activity approximately 8 × 106 Units/mg) as a sterile, lyophilized powder. The FDA approved the drug in 1997.