Janssen Pharmaceutica under his direction; code R 41 468, first described in the 1981 Life Sci paper by Leysen, Awouters, Kennis, Laduron, Vandenberk and Janssen. The first selective 5-HT2A antagonist, and the pharmacological tool behind the later 5-HT2/D2 antipsychotic idea. Family name is invented.