SOMAVERT® (pegvisomant for injection) Description

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Prescribing Information

SOMAVERT^® (pegvisomant for injection)
Description


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SOMAVERT contains pegvisomant for injection, an analog of human growth hormone (GH) that has been structurally altered to act as a GH receptor antagonist.

Pegvisomant is a protein of recombinant DNA origin containing 191 amino acid residues to which several polyethylene glycol (PEG) polymers are covalently bound (predominantly 4 to 6 PEG/protein molecule). The molecular weight of the protein of pegvisomant is 21,998 Daltons. The molecular weight of the PEG portion of pegvisomant is approximately 5000 Daltons. The predominant molecular weights of pegvisomant are thus approximately 42,000, 47,000, and 52,000 Daltons. The schematic shows the amino acid sequence of the pegvisomant protein (PEG polymers are shown attached to the 5 most probable attachment sites). Pegvisomant is synthesized by a specific strain of Escherichia coli bacteria that has been genetically modified by the addition of a plasmid that carries a gene for GH receptor antagonist. Biological potency is determined using a cell proliferation bioassay.

Amino Acid Sequence of Pegvisomant Protein

SOMAVERT is supplied as a sterile, white lyophilized powder intended for subcutaneous injection after reconstitution with 1 mL of Sterile Water for Injection, USP. SOMAVERT is available in single-dose sterile vials containing 10, 15, or 20 mg of pegvisomant protein (approximately 10, 15, and 20 U activity, respectively). Vials containing 10, 15, and 20 mg of pegvisomant protein correspond to approximately 21, 32, and 43 mg pegvisomant, respectively. Each vial also contains 1.36 mg of glycine, 36.0 mg of mannitol, 1.04 mg of sodium phosphate dibasic anhydrous, and 0.36 mg of sodium phosphate monobasic monohydrate.

SOMAVERT is supplied in packages that include a plastic vial containing diluent. Sterile Water for Injection, USP, is a sterile, nonpyrogenic preparation of water for injection that contains no bacteriostat, antimicrobial agent, or added buffer, and is supplied in single-dose containers to be used as a diluent.

SOMAVERT Safety Information

SOMAVERT is indicated for the treatment of acromegaly in patients who have had an inadequate response to surgery and/or radiation therapy and/or other medical therapies, or for whom these therapies are not appropriate. The goal of treatment is to normalize serum IGF-I levels.

Important Safety Information for Health Care Professionals

SOMAVERT is contraindicated in patients with a history of hypersensitivity to any of its components. The stopper on the vial of SOMAVERT contains latex.

Patients on opioids often needed higher serum pegvisomant concentrations to achieve appropriate IGF-I level suppression compared with patients not receiving opioids.

Functional effects of increased GH are prevented by GH receptor blockade; therefore, patients should be carefully observed for the clinical signs and symptoms of a GH-deficient state.

Acromegalic patients with diabetes mellitus being treated with insulin and/or oral hypoglycemic agents may require dose reductions of these therapeutic agents after the initiation of therapy with SOMAVERT.

Important safety information regarding periodic tumor size monitoring

Tumors that secrete GH may expand and cause serious complications. All patients with GH-secreting tumors, including those receiving SOMAVERT^®, should be carefully monitored for changes in tumor volume
Overall, mean tumor size was unchanged during the course of treatment in clinical studies
Tumor volume change did not appear to be influenced by whether or not patients had previously received radiation therapy

Important safety information regarding liver test monitoring

Monitor liver tests based on baseline values and changes during therapy according to the schedule in the full prescribing information
ALT was >3X but <10X the upper limit of normal (ULN) in patients treated with SOMAVERT (1.2%) vs placebo (2.1%)
– ALT and AST elevations occurred within 4 to 12 weeks after the start of therapy and did not appear to be related to the dose
In clinical studies with SOMAVERT, 2 patients (0.8%) experienced elevations of ALT and AST serum concentrations >10X the upper limit of normal (ULN)
– In both patients, the elevations normalized after discontinuation of the medicine

If a patient develops liver test elevations, or any other symptoms of liver dysfunction while receiving SOMAVERT, please see Liver Tests section of full Prescribing Information.

The most common adverse events (>10% and at frequencies greater than placebo) in 1 of the 3 active treatment arms in a placebo-controlled study (n = 112) include infection, pain, diarrhea, nausea, flu syndrome, abnormal liver function tests, and injection-site reaction.

Injection sites should be rotated daily to help prevent lipohypertrophy.

The maximum daily maintenance dose should not exceed 30 mg/day.

Please see full prescribing information.

SOMAVERT^® (pegvisomant for injection) PI

Please see Patient Package Insert.

SOMAVERT^® (pegvisomant for injection) PPI

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