Discovery of new molecules for future treatment of infertility.

The introduction of recombinant gonadotrophins for the treatment of infertility has been an important advance in improving the quality and consistency of therapeutics offered to patients seeking care from fertility specialists. Over the past decade, a number of investigators have discovered small molecules that mimic the effects of FSH and LH. Despite extensive medicinal chemistry efforts from many institutes, including Serono Research Institute, and reasonable in-vitro activity, receptor-targeted agonists have not yet been successfully developed for clinical use, based upon results generated in animal models of follicular stimulation (FSH-like) or ovulation induction [human chorionic gonadotrophin (HCG)-like]. A different approach to gonadotrophin mimicry was identified that modifies intracellular signalling pathways common to gonadotrophins. Phosphodiesterase type 4 enzyme inhibitors and selective prostaglandin E receptor (EP2/EP4) agonists have been demonstrated to mimic the effects of HCG to induce ovulation following oral administration. Multiple approaches with small molecules have been attempted to activate the FSH receptor and initiate cAMP-dependent mechanisms. Pharmacodynamic effects of FSH on follicular growth were demonstrated by inhibiting a different enzyme pathway with a small molecule, albeit in the presence of very low concentrations of circulating FSH. These results raise the possibility that in the future orally active agents can be used in combination with injectable gonadotrophins or perhaps independent of gonadotrophins for first-line interventions for infertility.