Pegvisomant

12.1 Mechanism of Action Pegvisomant selectively binds to growth hormone (GH) receptors on cell surfaces, where it blocks the binding of endogenous GH, and thus interferes with GH signal transduction. Inhibition of GH action results in decreased serum concentrations of IGF-1, as well as other GH-responsive serum proteins such as free IGF-1, the acid-labile subunit of IGF-1 (ALS), and insulin-like growth factor binding protein-3 (IGFBP-3).

1 INDICATIONS AND USAGE SOMAVERT is indicated for the treatment of acromegaly in patients who have had an inadequate response to surgery or radiation therapy, or for whom these therapies are not appropriate. The goal of treatment is to normalize serum insulin-like growth factor-1 (IGF-1) levels. SOMAVERT is a growth hormone receptor antagonist indicated for the treatment of acromegaly in patients who have had an inadequate response to surgery or radiation therapy, or for whom these therapies are not appropriate. The goal of treatment is to normalize serum insulin-like growth factor-1 (IGF-1) levels. ( 1 )

2 DOSAGE AND ADMINISTRATION • Administer a 40 mg loading dose subcutaneously under physician supervision. ( 2.1 ) • After proper injection instruction, on day after loading dose, patients or caregivers begin daily subcutaneous injections of 10 mg. ( 2.1 ) • Adjust dosage in 5 mg increments or decrements until serum IGF-1 concentrations are maintained within age-adjusted normal range. Do not adjust dosage based on growth hormone (GH) levels or signs or symptoms of acromegaly. ( 2.1 ) • Dosage range is 10 mg to 30 mg once daily. ( 2.1 ) • Perform liver tests prior to first dosage and if greater than 3 times upper limit of normal should work-up prior to SOMAVERT administration. ( 2.2 ) • Follow reconstitution and injection procedures. ( 2.3 , 2.4 ) 2.1 Dosage Information The recommended loading dose of SOMAVERT is 40 mg given subcutaneously, under healthcare provider supervision. Provide proper training in subcutaneous injection technique to patients or their caregivers so they can receive once daily subcutaneous injections. On the next day following the loading dose, instruct patients or their caregivers to begin daily subcutaneous injections of 10 mg of SOMAVERT. Titrate the dosage to normalize serum IGF-1 concentrations (serum IGF-1 concentrations should be measured every four to six weeks). The dosage should not be based on growth hormone (GH) concentrations or signs and symptoms of acromegaly. It is unknown whether patients who remain symptomatic while achieving normalized IGF-1 concentrations would benefit from increased SOMAVERT dosage. • Increase the dosage by 5 mg increments every 4–6 weeks if IGF-1 concentrations are elevated. • Decrease the dosage by 5 mg decrements every 4–6 weeks if IGF-1 concentrations are below the normal range. • IGF-1 levels should also be monitored when a SOMAVERT dose given in multiple injections is converted to a single daily injection [see Clinical Pharmacology (12) ] . The recommended dosage range is between 10 mg to 30 mg given subcutaneously once daily and the maximum daily dosage is 30 mg given subcutaneously once daily. 2.2 Assess Liver Tests Prior to Initiation of SOMAVERT Prior to the start of SOMAVERT, patients should have an assessment of baseline levels of liver tests [serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), serum total bilirubin (TBIL), and alkaline phosphatase (ALP)]. For recommendations regarding initiation of SOMAVERT based on baseline liver tests and recommendations for monitoring of liver tests while on SOMAVERT, refer to Table 1 in Warning and Precautions (5.2) . 2.3 Loading Dose Injection Procedure The following instructions are for the healthcare provider to reconstitute and prepare the 40 mg loading dose. The healthcare provider will need to reconstitute 2 vials of lyophilized powder of SOMAVERT each containing 20 mg of pegvisomant with supplied diluent [two vials of lyophilized powder and two syringes containing 1 mL of diluent (Sterile Water for Injection, USP) will be needed for the 40 mg loading dose]. The healthcare provider will also need to inject the reconstituted SOMAVERT solution twice into the patient's upper arm, upper thigh, abdomen, or buttocks (each injection in a different area). a) Before administering the loading dose, remove 1 vial of lyophilized powder of SOMAVERT containing 20 mg of pegvisomant and one syringe containing 1 mL of diluent from the refrigerator, if refrigerated, about 10 minutes prior to the planned injection time. b) Reconstitute the first 20 mg vial of lyophilized powder of SOMAVERT containing 20 mg of pegvisomant with diluent. When using the diluent in the syringe, inject the contents of the syringe slowly onto the sides of the vial containing lyophilized powder of SOMAVERT. Do not inject the diluent directly on the powder. c) Do not invert the vial or shake the solution as this may cause denaturation of the pegvisomant protein. Slowly swirl the solution to ensure that all of the lyophilized powder has gone into solution. If foaming of the reconstituted SOMAVERT solution is seen, the solution is likely damaged and therefore inappropriate to inject. d) Visually inspect the reconstituted SOMAVERT solution for particulate matter and discoloration prior to administration. The reconstituted solution should be clear. If the solution is cloudy, do not use it. Once reconstituted, the solution will contain 20 mg of pegvisomant in 1 mL of solution. e) Withdraw the 1 mL reconstituted SOMAVERT solution. The solution must be administered immediately after reconstitution. f) Inject the first reconstituted SOMAVERT solution (20 mg/mL) subcutaneously into the patient's upper arm, upper thigh, abdomen, or buttocks using a 90-degree angle. g) Repeat steps (a) to (e) to reconstitute the second SOMAVERT dose of 20mg. h) Finally, inject the second reconstituted SOMAVERT solution (20 mg/mL) subcutaneously into the patient's upper arm, upper thigh, abdomen, or buttocks using a 90-degree angle (different are

6 ADVERSE REACTIONS Clinically significant adverse reactions that appear in other section of the labeling include: • Hypoglycemia Associated with GH Lowering in Patients with Diabetes Mellitus [see Warnings and Precautions (5.1) ] • Liver Toxicity [see Warnings and Precautions (5.2) ] • Cross-Reactivity with GH Assays [see Warnings and Precautions (5.3) ] • Lipohypertrophy [see Warnings and Precautions (5.4) ] • Systemic Hypersensitivity [see Warnings and Precautions (5.5) ] Elevations of serum concentrations of ALT and AST greater than ten times the ULN were reported in two patients (0.8%) exposed to SOMAVERT in pre-approval clinical studies. One patient was rechallenged with SOMAVERT, and the recurrence of elevated transaminase levels suggested a probable causal relationship between administration of the drug and the elevation in liver enzymes. A liver biopsy performed on the second patient was consistent with chronic hepatitis of unknown etiology. In both patients, the transaminase elevations normalized after discontinuation of the drug. Elevations in ALT and AST levels were not associated with increased levels of TBIL and ALP, with the exception of two patients with minimal associated increases in ALP levels (i.e., less than 3 times ULN). The transaminase elevations did not appear to be related to the dose of SOMAVERT administered, generally occurred within 4 to 12 weeks of initiation of therapy, and were not associated with any identifiable biochemical, phenotypic, or genetic predictors. Most common reported adverse reactions (>6%) are infection, pain, nausea, diarrhea, abnormal liver tests, flu syndrome, injection site reaction. ( 6 ) To report SUSPECTED ADVERSE REACTIONS, contact Pfizer Inc. at 1-800-438-1985 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch . 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. In a 12-week randomized, placebo-controlled, double-blind, fixed-dose study of SOMAVERT in subjects with acromegaly, 32 subjects received placebo and 80 subjects received SOMAVERT once daily [see Clinical Studies (14) ] . A total of 108 subjects (30 placebo, 78 SOMAVERT) completed 12 weeks of study treatment. Overall, eight patients with acromegaly (5.3%) withdrew from pre-marketing clinical studies because of adverse events, including two patients with marked transaminase elevations, one patient with lipohypertrophy at the injection sites, and one patient with substantial weight gain. Most adverse events did not appear to be dose-dependent. Table 3 shows the incidence of adverse events that were reported in at least two patients treated with SOMAVERT and at frequencies greater than placebo during the 12-week, placebo-controlled study. Table 3. Adverse Reactions in a 12-week Placebo-Controlled Study in Patients with Acromegaly Table includes only those events that were reported in at least 2 patients and at a higher incidence in patients treated with SOMAVERT than in patients treated with placebo. Placebo n=32 SOMAVERT 10 mg/day n=26 15 mg/day n=26 20 mg/day N=28 Infection The 6 events coded as "infection" in the group treated with SOMAVERT 10 mg were reported as cold symptoms (3), upper respiratory infection (1), blister (1), and ear infection (1). The 2 events in the placebo group were reported as cold symptoms (1) and chest infection (1). 2 (6%) 6 (23%) 0 0 Pain 2 (6%) 2 (8%) 1 (4%) 4 (14%) Nausea 1 (3%) 0 2 (8%) 4 (14%) Diarrhea 1 (3%) 1 (4%) 0 4 (14%) Abnormal liver function tests 1 (3%) 3 (12%) 1 (4%) 1 (4%) Flu syndrome 0 1 (4%) 3 (12%) 2 (7%) Injection site reaction 0 2 (8%) 1 (4%) 3 (11%) Dizziness 2 (6%) 2 (8%) 1 (4%) 1 (4%) Accidental injury 1 (3%) 2 (8%) 1 (4%) 0 Back pain 1 (3%) 2 (8%) 0 1 (4%) Sinusitis 1 (3%) 2 (8%) 0 1 (4%) Chest pain 0 1 (4%) 2 (8%) 0 Peripheral edema 0 2 (8%) 0 1 (4%) Hypertension 0 0 2 (8%) 0 Paresthesia 2 (6%) 0 0 2 (7%) 6.2 Postmarketing Experience Adverse Reactions from Postmarketing Spontaneous Reports The following adverse reactions have been identified during post-approval use of SOMAVERT. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure. Systemic hypersensitivity reactions including anaphylactic reactions, laryngospasm, angioedema, generalized skin reactions (rash, erythema, pruritus, urticaria) have been reported in post-marketing use. Some patients required hospitalization. Symptoms did not re-occur in all patients after re-challenge [see Warnings and Precautions (5.5) ] . Adverse Reactions from an Observational Study ACROSTUDY was an international observational registry that captured long term safety data in 2221 patients with acromegaly treated with SOMAVERT fo

7 DRUG INTERACTIONS • Insulin and/or Oral hypoglycemic Agents: Patients with acromegaly and with diabetes mellitus may require careful monitoring and dose reductions of insulin and/or oral hypoglycemic agents. ( 5.2 , 7.1 ) • Opioids: Patients on opioids may need higher SOMAVERT doses to achieve appropriate IGF-1 suppression. ( 7.2 ) 7.1 Insulin and/or Oral Hypoglycemic Agents After initiation of SOMAVERT, patients with acromegaly and diabetes mellitus treated with insulin and/or oral hypoglycemic agents may require dose reductions of insulin and/or oral hypoglycemic agents [see Warnings and Precautions (5.1) ] . 7.2 Opioids In clinical studies, patients taking opioids often needed higher SOMAVERT doses to normalize IGF-1 concentrations compared with patients not receiving opioids. The mechanism of this interaction is not known.