Enthusiasm For Amgen Obesity Drug Palls

Amgen's platform technology in its anti-obesity program, the ob gene and its peptide product leptin, may not be the potential money-spinner for which the company wished, if questions raised in the New England Journal of Medicine turn out to be true. Amgen attracted much attention last year when it revealed that giving leptin to obese rats resulted in a decline in weight and food intake (Marketletter July 31, 1995).

The study reported in the NEJM implies that obese people are not deficient in leptin as was once supposed. Rather, they have elevated levels of the protein in their blood (an average of four times and up to 20-to-30 times as much as lean people), which suggests that the root of their problem lies not with a deficiency but with an inability to recognize the signal, which might be termed "leptin-resistance," at the level of the leptin receptor or associated secondary messenger systems.

This report backs up similar findings reported at the end of last year in very obese people (Marketletter September 11, 1995). However, a broad range of leptin levels was encountered in the NEJM study, including some patients with low concentrations of the protein, so it may be that some obese patients would respond to leptin administration. Indeed, the finding suggests that obesity is a multifactorial condition, so leptin administration may benefit some patients.