Lantus rumours, share prices and IGF-1

Sanofi-aventis’s share price has been affected by rumours of a cancer risk with their insulin analogue Lantus.

The source of the rumour and whether it consists of case reports, population studies, or further in-vitro work is not known but there have been concerns about glargine before. It appears to stimulate IGF-1 receptors more than human insulin.

However, a recent review said “Although one study reported increased binding affinity of insulin glargine for the IGF-1R and increased mitogenic potential in cells with excess IGF-1Rs (Saos/B10 osteosarcoma cells), most in vitro binding-affinity and cell-culture studies have demonstrated behaviour of insulin glargine comparable to that of RHI [regular human insulin] for both IR [insulin receptors] and IGF-1R binding, insulin signalling, and metabolic and mitogenic potential. Currently published in vivo carcinogenic studies and human clinical trial data have shown that insulin glargine is not associated with increased risk for either cancer or the development or progression of diabetic retinopathy.”1

This type of theoretical long term risk associated with a medication is not one that is readily explored by case reports. Looking at the glargine case report literature there seems to be a good number on, for example, its short term safety during pregnancy.

I haven’t had any cases submitted on the successful use of glargine in oncology patients – especially those with tumours expressing IGF-1 receptors – who remained clinically stable, but I’d be interested to see them.

1) Le Roith D. Insulin glargine and receptor-mediated signalling: clinical implications in treating type 2 diabetes. Diabetes Metab Res Rev. 2007 Nov;23(8):593-9.