Another cloud has obscured the development horizon for neurotrophic factors. This time, Regeneron Pharmaceuticals Inc.'s Axokine has been found to interact with herpes simplex virus, which may limit the compound's use as a treatment for obesity and diabetes.

Nevertheless, the company has reasons for remaining committed to developing ciliary neurotrophic factors, despite losing another development partner for Axokine, a second generation CNTF, over the HSV issue.