• Reductions in tumour size from Baseline to Month 12 as assessed using MRI.
  

• To assess the change in tumour size at Month 3 and Month 6 compared to baseline assessed using MRI.
  
• To assess the change in the GH and IGF-1 levels at all assessment timepoints in comparison to the baseline visit.
  
• To assess the change in visual fields at all assessment timepoints in comparison to baseline, as assessed using a Goldman Visual Fields Analyser.
  
• To assess the change in patient symptom scores at all assessment timepoints in comparison to the baseline visit as assessed using numerical rating scales.
  
• To assess the change in quality of life scores (as assessed using the SF-36 questionnaire) at all assessment timepoints in comparison to the baseline visit.
  
• To determine the incidence of occurrence of new hormonal axes defects arising pre-operatively between baseline and Month 12.
  
• To determine the proportion of patients requiring surgery during the twelve month study period (i.e. those with tumour progression or intolerable symptoms on medical therapy).
  
• To evaluation the safety and tolerability of each dose of Somatuline Autogel, as assessed by:
  
• o the maximum tolerated dose for each patient,
  
• o the incidence of adverse events (including findings on liver and gallbladder ultrasound),
  
• o changes in concomitant medication,
  
• o the incidence of clinically significant changes in vital signs or ECG,
  
• o the incidence of clinically significant laboratory or physical examination findings.
  

Inclusion Criteria:

Patients must satisfy all of the following entry criteria before they will be allowed to participate in the study:

• The patient must give written (personally signed and dated) informed consent before completing any study-related procedure, which means any assessment or evaluation that would not have formed part of their normal medical care.
• The patient is over 18 years of age inclusive.
• The patient has active acromegaly as diagnosed by oral glucose tolerance test and IGF-1 measurement. Acromegaly must be confirmed prior to study entry based on failure to suppress GH during an oral glucose tolerance test and IGF-1 above the normal range.
• The patient has a pituitary adenoma tumour size greater than 5 mm along the longest axis on MRI.
• The patient has a life expectancy of at least 2 years.
• The patient is able and willing to comply with the requirements of the protocol.

Exclusion Criteria:

• The patient is considered unfit for surgery due to comorbidity that is unlikely to resolve with control of acromegaly.
• The patient has a significant visual field defect thought to be due to optic chiasm compression at the time of presentation where the risk of visual loss is considered too great to delay surgery. (Note: Not all patients with visual field defects will be excluded - this decision will be made at the joint pituitary clinic). Following informed discussion with the individual medical therapy will be offered with close monitoring of visual fields as per protocol. If visual field assessment shows a further deterioration then surgery will be offered at that point. The available literature strongly supports the view that further tumour growth is unlikely during somatostatin analogue therapy.
• The patient has a pituitary adenoma tumour of 5 mm or less along the longest axis, with margins clearly defined within pituitary fossa.
• The patient has had any prior pituitary surgery (adenectomy).
• The patient has received pituitary radiotherapy within one year prior to screening.
• The patient has been previously treated with a GH antagonist or a somatostatin analogue.
• The patient has clinically significant renal or hepatic abnormalities.
• The patient has a known allergy or hypersensitivity to any of the test compounds or materials.
• The patient is pregnant or lactating (female patients of child-bearing potential (i.e. who are not surgically sterile or at least 1 year post-last menstrual period) must have a negative urine pregnancy test at the baseline visit).
• The patient is a female at risk of pregnancy during the study, not taking adequate precautions against pregnancy.
• The patient has received any investigational drug therapy within 30 days prior to the study, or is scheduled to receive such a drug during the study period.
• The patient has previously entered this study.