Obesity causes 600 premature deaths per week in the UK and existing treatments are not effective. When humans eat, the bowels naturally secrete chemicals into the bloodstream which make people feel full and which stop eating. One of these chemicals is known as Peptide YY (PYY). The investigators have previously shown that injections of PYY reduce appetite and food intake in human volunteers. The investigators have now developed a very similar chemical, Y242, as a treatment for obesity. Y242 has been tested in animals and has been shown to be safe, to reduce their appetite, and to last for much longer than PYY itself. This study will test Y242 to ensure that it is well tolerated in humans, and to see how long it lasts in the blood stream after being injected under the skin. It will also look for any effects on appetite.

Obesity causes 600 premature deaths per week in the UK and existing treatments are less than ideal. Intravenous infusion of a hormone called PYY reduces food intake but its effects only last for a few hours and it can cause nausea. Y242 is a longacting analogue of PYY. Given subcutaneously in rodents, it has a profile of action of at least 72 hours and strongly inhibits food intake. It causes weight loss without behavioural effects. With MRC funding, Y242 has passed Good Laboratory Practice toxicology testing and the present proposal is a first in human study to investigate its safety, tolerability and pharmacokinetics in overweight but otherwise healthy men.

The study is a combined single ascending dose (part A) and multiple ascending dose (part B) Phase 1 investigation. The primary objective is to investigate safety and tolerability. The secondary objective is to assess Y242's pharmacokinetic (PK) profile. Possible effects on food consumption will be explored. For part A up to 48 subjects are planned, with up to 40 subjects for part B. In each part subjects are divided into groups, each of which is dosed with the same level, starting with a single dose (part A) much lower than is expected to cause an effect. Subjects are admitted to a Unit so they can be closely observed for adverse effects and safety tests, blood concentrations of the drug and food and liquid intake and output will be monitored. Subjects are allocated at random (like tossing a coin) to receive Y242 or placebo (dummy). Safety, tolerability and pharmacokinetic data will be summarised and available results considered in deciding dose escalation, with stopping rules designed to enable us to explore the relationship between dose and adverse effect (eg nausea) without causing unacceptable nausea or other symptoms in the volunteers.

Inclusion Criteria:

• Adult males aged 18 to 50 years inclusive with BMI between 23.0 and 30.0 kg/m^2 inclusive;
• Subjects who are healthy as determined by pre study medical history, physical examination and 12 lead ECG;
• Subjects whose clinical laboratory test results are either within the normal range or if outside this range the abnormalities are judged to be not clinically relevant and are acceptable to the Investigator;
• Subjects who are negative for hepatitis B surface antigen (HBsAg), hepatitis C antibody and human immunodeficiency virus (HIV) I and II tests at screening;
• Subjects who are negative for drugs of abuse and alcohol tests at screening and admissions;
• Subjects who are non-smokers for at least 3 months preceding screening;
• Subjects who agree to use medically acceptable methods of contraception for at least 3 months after study drug administration;
• Subjects who are able and willing to give written informed consent.

Exclusion Criteria:

• Subjects who do not conform to the above inclusion criteria;
• Subjects who have a clinically relevant history or presence of gastrointestinal (especially associated with vomiting), respiratory, renal, hepatic, haematological, lymphatic, neurological (especially if associated with balance disorders or vomiting e.g. migraine or labyrinthitis), cardiovascular, psychiatric, musculoskeletal, genitourinary, immunological, dermatological, connective tissue diseases or disorders;
• Subjects who have a clinically relevant surgical history;
• Subjects who have a clinically relevant family history;
• Subjects who have a history of relevant atopy;
• Subjects who have a history of relevant drug hypersensitivity;
• Subjects who have a history of alcoholism;
• Subjects who have a history of drug abuse;
• Subjects who have a history of migraine;
• Subjects who consume more than 21 units of alcohol a week (unit = 1 glass of wine (125 mL) = 1 measure of spirits = ½ pint of beer);
• Subjects who have a significant infection or known inflammatory process on screening;
• Subjects who have acute gastrointestinal symptoms at the time of screening or admission (e.g. nausea, vomiting, diarrhoea, heartburn);
• Subjects who have an acute infection such as influenza at the time of screening or admission;
• Subjects who have used prescription drugs within 4 weeks of first dosing;
• Subjects who have used over the counter medication excluding routine vitamins and paracetamol but including megadose (intake of 20 to 600 times the recommended daily dose) vitamin therapy within 7 days of first dosing, unless agreed as not clinically relevant by the Principal Investigator and Sponsor;
• Subjects who have donated blood or blood products within 3 months of Day -2 (admission);
• Subjects who have used any investigational drug in any clinical trial within 3 months of Day -2 (admission);
• Subjects who have received the last dose of investigational drug greater than 3 months ago but who are on extended follow-up;
• Subjects who have previously received Y242;
• Subjects who are vegans or have any dietary restrictions;
• Subjects who cannot communicate reliably with the Investigator;
• Subjects who are unlikely to co-operate with the requirements of the study;
• History or evidence of abnormal eating behaviour, as observed through the Dutch Eating Behaviour (DEBQ) and SCOFF questionnaires at screening.

Adult males aged 18 to 50 years inclusive with BMI between 23.0 and 30.0 kg/m^2 inclusive

73 days until final follow up visit

The subjects were queried regularly on all study days using non-leading questions, such as "How do you feel?" In addition, all AEs reported spontaneously during the course of the study were recorded.

Part A: Treatments were administered single-blind; subjects were blinded with regard to treatment and clinical staff remained blinded with regard to treatment until the Safety Committee meeting. Part B was double blind.