The quest for a new obesity agent was dealt a further blow last week when Amylin and Takeda announced that they are ceasing development of their pramlintide/metreleptin combination. Clinical trials were suspended earlier this year owing to antibody-related laboratory findings, and the companies said their decision to halt development altogether was based on a reassessment of their commercial prospects as well as taking into consideration the evolving dynamics within the field of obesity drug development.

Despite its injectable mode of action which would likely deter some patients, the pramlintide/metreleptin combination had shown particular promise, given the double-digit weight loss efficacy it had demonstrated in Phase II studies. The suspension of this promising agent follows in the wake of the FDA's recent rejection of three other obesity compounds: Vivus's Qnexa, Arena/Eisai's Lorqess and Orexigen/Takeda's Contrave over a variety of safety issues, and it is likely that these failures weighed heavily in the decision to discontinue pramlintide/metreleptin.

So, what remains in the obesity pipeline. Of the three aforementioned agents which received Complete Response Letters from the FDA last year, Qnexa is the only one that we believe is likely to convince the FDA of its favorable risk:benefit profile. Lorqess's poor weight loss efficacy, in combination with question marks over its safety, mean that this agent is unlikely to gain approval, and the requirement for Orexigen to carry out a preapproval cardiovascular outcomes study on Contrave means that a launch for this agent is no longer realistic.

Medical experts who lament the lack of safe and effective obesity treatments, have called for clearer guidelines in the development of obesity agents. The FDA is planning a general advisory committee meeting early next year to discuss requirements for cardiovascular assessments of obesity drugs. Thought leaders interviewed by Decision Resources predict that the drug development guidelines for obesity drugs are likely to become more aligned with those for type 2 diabetes agents, which will mean a requirement for large cardiovascular safety trials, and we believe this may act as a further deterrent to companies seeking to develop agents to treat obesity as a whole.

So, again, what is left in the pipeline. One agent that is showing promise in Phase III trials is Novo Nordisk's GLP-1 analogue Victoza, which is currently marketed as a treatment for type 2 diabetes. This agent combines weight loss with excellent HbA1C control, and may prove effective in preventing the onset of type 2 diabetes. Given the high safety bar demonstrated by the FDA, it's likely that an agent that addresses medical need in addition to providing weight loss will have a better chance of gaining approval. The fact that Victoza has already passed regulatory requirements for diabetes is also promising, given next year's FDA meeting to discuss regulatory guidelines. Looking to the future with other obesity agents, interviewed thought leaders suggest that the development of agents which address the obese patients associated medical needs, such as diabetes or sleep apnea, in addition to providing weight loss, may be the best path forward for gaining regulatory approval. Therefore, we need to keep an eye on the diabetes pipeline for future development in the obesity space.

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