Immediate initiation of PD-L1/PD-1 inhibition in urothelial carcinoma (UC) patients with at least stable disease following 1st line platinum-based chemotherapy instead of waiting for progressive disease is a compelling strategy which has been proven to be effective in the Javelin Bladder 100 trial (NCT02603432)14. After completion of chemotherapy (with stable disease (SD), partial or complete response (PR, CR) as best response, patients received maintenance avelumab treatment until progressive disease, unacceptable toxicity or patient withdrawal. As a consequence of this design a proportion of the patients were treated 2 years or even longer. However, the optimal duration of immunotherapy in this context of maintenance therapy is unknown.