For decades plagued by therapies of limited efficacy, the recent arrival of an embarrassment of riches in effective therapeutics for inflammatory bowel disease 1, 2 – likely to grow further in coming years 3-6 – has made personalization of therapy ever more urgent. Practicing physicians have no other option than to follow a rather mundane step-up and trial-and-error approach. The results of an exemplary biomarker trial conducted by Janssen and published in this issue 7 showcases how hard progress in this area is – and points to the sobering prospect that the current trial-and-error approach may stay for some longer.