Inclusion Criteria:

• The patient must have had documentation supporting the diagnosis of acromegaly, including elevated GH and/or IGF-1 levels
• The patient is treated with pegvisomant, because of IGF-1 level remaining above ULN when treated with somatostatin analogue, on a daily basis for at least 3 months and has normal (age and sex adjusted) IGF-1 level, or IGF-1 level above the upper limit of normal (ULN) after treatment with pegvisomant 30 mg per day, OR the patient is treated with lanreotide Autogel or octreotide LAR for at least 6 months including 3 months at the highest marketed dose and has a serum IGF-1 level above ULN, 28 days after the last injection
• At the end of the run-in period, The patient has a serum IGF-1 level above 1.2 x ULN, or a serum IGF-1 level between ULN and 1.2 x ULN and a serum GH nadir > 1 µg/L (assessed by an OGTT), 28 days after the 3rd injection of lanreotide Autogel 120 mg OR the patient is diabetic and has a serum IGF-1 level above 1.2 ULN, 28 days after the 3rd injection of lanreotide Autogel 120 mg

Exclusion Criteria:

• The patient has undergone pituitary surgery or radiotherapy within 6 months prior to study entry, or it is anticipated that it will be done during the study
• The patient has already been treated with a somatostatin analogue associated with a GH antagonist
• The patient has received dopamine agonist within 6 weeks prior to the study entry
• The patient has abnormal hepatic function at study entry (defined as AST, ALT, GGT, alkaline phosphatase, prothrombin time or total bilirubin above 2 ULN)
• The patient is at risk of pregnancy or is lactating