Exenatide [AC002993, AC2993A, AC 2993, LY2148568, exendin 4], a glucagon-like peptide-1 (GLP-1) agonist, is a synthetic exendin 4 compound under development with Amylin Pharmaceuticals for the treatment of type 2 diabetes. Both exendin 4 and its analogue, exendin 3, are 39-amino acid peptides isolated from Heloderma horridum lizard venom that have different amino acids at positions 2 and 3, respectively. Exendins are able to stimulate insulin secretion in response to rising blood glucose levels, and modulate gastric emptying to slow the entry of ingested sugars into the bloodstream. Amylin Pharmaceuticals acquired exclusive patent rights for the two exendin compounds (exendin 3 and exendin 4) from the originator, Dr John Eng (Bronx, NY, US). On 20 September 2002, Amylin and Eli Lilly signed a collaborative agreement for the development and commercialisation of exenatide for type 2 diabetes. Under the terms of the agreement, Eli Lilly has paid Amylin a licensing fee of 80 million US dollars and bought Amylin's stock worth 30 million US dollars at 18.69 US dollars a share. After the initial payment, Eli Lilly will pay Amylin up to 85 US dollars million upon reaching certain milestones and also make an additional payment of up to 130 million US dollars upon global commercialisation of exenatide. Both companies will share the US development and commercialisation costs, while Eli Lilly will pick up up to 80% of development costs and all commercialisation costs outside the US. Amylin and Eli Lilly will equally share profit from sales in the US, while Eli Lilly will get 80% of the profit outside the US and Amylin will get the rest. This agreement has also enabled Amylin to train its sales force to co-promote Lilly's human growth hormone Humatrope. Alkermes will receive research and development funding and milestone payments, and also a combination of royalty payments and manufacturing fees based on product sales. Alkermes undertakes the responsibility for the development of several initial formulations of the long-acting drug and manufacturing of the final product, while Amylin will be responsible for clinical trials, regulatory filings and worldwide marketing. The goal of the exenatide LAR programme is to develop a once-a-month injectable formulation of exenatide. In November 2003, Amylin announced positive results from the second of three pivotal, phase III studies that evaluated the effects of exenatide in combination with sulfonylureas in 377 randomised patients with type 2 diabetes. The design of the study was similar to that from the first study. The final third phase III study of exenatide was completed in November 2003. This study investigated the effects of exenatide in combination with metformin and sulfonylureas. Amylin and Eli Lilly announced that all of the pivotal phase III trials met the primary glucose control endpoint as measured by glycosylated haemoglobin. An NDA submission for exenatide is projected for mid-2004. A phase II, dose-ascending study in patients with type 2 diabetes was initiated in June 2002. This multicentre (US), double-blind, placebo-controlled study evaluated the safety, tolerability and the pharmacokinetic profile of exenatide LAR in up to 100 patients with type 2 diabetes. A phase I study of exenatide LAR began in Europe in March 2001 and was completed in Q3 2001. A long-acting, sustained-release formulation of exenatide lowered both pre- and post-meal glucose concentration during a 24h period in patients with type 2 diabetes. In November 2002, analysts at Prudential Financial estimated that exenatide, pending approval, has the potential to reach sales of 477 million US dollars in 2006.