The study is designed to investigate the safety, tolerability and efficacy of DG3173 in untreated acromegaly patients. Twenty patients received ascending single doses of DG3173 and one dose of octreotide, the current gold standard of medical therapy for acromegaly, with each patient receiving all doses of DG3173 as well as octreotide.

Inclusion Criteria:

• Men, women of non childbearing potential or women of child bearing potential who either abstain from sexual intercourse, have a sterile partner or practice a medically approved double barrier method of contraception
• Diagnosis of acromegaly of pituitary origin
• Have age adjusted Insulin like Growth Factor 1 (IGF-1) concentrations ≥1.5 times the upper limit of normal range on two consecutive measurements in the 6 months prior to the first dosing day (including the measurement to be made at screening [Visit 2])
• Have a random hGH level of ≥5 µg/L in the 6 months prior to or at screening (Visit 2)
• Have given written informed consent
• Ability to comply with the requirements of the protocol of the study

Exclusion Criteria:

• Previous specific treatment for acromegaly in the 6 months prior to screening (Visit 2), including somatostatin analogues (SSAs), surgery, radiotherapy and pegvisomant
• Treatment with dopamine agonists in the 3 months prior to screening (Visit 2)
• Uncontrolled hypertension or orthostatic hypotension
• Type I diabetes mellitus, poorly-controlled type II diabetes mellitus (glycosylated haemoglobin [HbA1c]≥7.5%) and patients requiring insulin treatment
• Gallstones or gravel that could cause biliary obstruction
• Hyperprolactinaemia
• Participation in a clinical study within 60 days prior to screening (Visit 2)
• Receipt of blood, blood products or plasma derivatives 60 days prior to screening (Visit 2)
• Pregnancy or lactation
• A history of active alcohol abuse or drug addiction
• Positive viral serology screening result for hepatitis B surface antigen, antibodies to hepatitis C virus, or human immunodeficiency virus type 1 and 2
• Evidence or suspicion of tumour expansion
• Clinically significant abnormality in screening ECG
• Any clinically significant abnormal laboratory safety test (biochemistry, haematology and dipstick urinalysis) in the opinion of the Investigator
• Any disease which in the Investigator's opinion would exclude the patient from the study