The DENIM trial is a randomised phase III study in patients with UPM comparing MesoPher, as a maintenance treatment after completion of first line chemotherapy versus best supportive care (BSC). Eligible patients were non progressing after 4-6 cycles of platinum/pemetrexed. The DENIM study failed to show increased OS with MesoPher. Likely the long interval between chemotherapy and the start of treatment caused that most patients had already disease progression before or during the first 3 DC treatments, prohibiting the induction of an effective immune response. This interval was extended compared to earlier MesoPher studies because randomization and additional sterility tests.