Background: With increasing armamentarium in advanced melanoma management, the impact of various strategies remains to be determined including the importance of time to switch from one treatment to another. We report the impact of time to IPI/APD non-planned switch on APD efficacy in real life patients within MelBase (MB). Methods: MB is a French multicentric biobank dedicated to the prospective follow-up (FU) of unresectable stage III or IV melanoma with 1102 patients included since March 2013. Data were collected (Sept.2016) and analyzed (demography, overall survival (OS), progression-free survival (PFS), response rate, multivariate analysis, safety). Results: 71 patients were treated with IPI/APD sequence. 72% received 4 IPI injections. The median time to switch was 1.7 months (0.36-3). The characteristics at the initiation of APD are: mean age 64 yrs, PS 0-1 80%, elevated LDH 34%, BRAF WT 90%, brain metastasis 25%, ≥ 3 metastatic organ sites (MOS) 49%, median FU 11.9 months, OS 20 months (95%CI:12.6-NR), PFS 3.5 months (95%CI:2.9-6.2). The best overall response was 25%, disease control rate was 54% with a low toxicity profile (17% grade 3/4). In a multivariable analysis, longer time to switch was significantly associated with better OS (adjusted HR 0.38 per 1 more month, 95%CI:0.14-0.93), as well as ECOG 0-1 (aHR 3.11, 95%CI:0.99-9.72) and LDH < ULN (aHR 3.32, 95%CI:1.26-8.75). In addition, the association of time to switch with OS vary significantly according to the number of MOS ( < 3 MOS aHR 0.25, 95%CI:0.10-0.62; ≥3 MOS aHR 0.99 95%CI:0.41-2.39) and AJCC stage (M0/1a/1b aHR 0.06, 95%CI:0.01-0.43 ; M1c aHR 0.77, 95%CI:0.39-1.54). Conclusions: In patients who failed IPI treatment, longer survival after APD was associated to time to switch only in patients with favorable baseline factors. Such results are probably more related to the slow kinetics of the disease than to the delay itself. Our results are different from Blank et al.(ESMO 2016) who tested a planned switch, immediately after 2 IPI perfusions, and showed overall response rate close to IPI+APD association. We are currently conducting a similar study on the reverse sequence (APD/IPI) and the role on IPI efficacy.