Background Progress in developing effective salvage therapies for UC is warranted. Alisertib is an orally available, selective inhibitor of the aurora kinase A. Methods A single-group, phase 2 trial was conducted with alisertib 50 mg orally BID for 7 days, with 14d rest until disease progression (PD) (NCT02109328). The primary endpoint (EP) was RECIST 1.1 objective response-rate (ORR, H0 ≤ 5 %, H1 ≥ 20 %, α = 10 % and β = 20 %). Eligibility included failure of at least one platinum-based regimen. Results From 10/2014 to 04/2015, 22 patients were enrolled (20 evaluable for response), 8 (36.4 %) in second-line and 14 (63.6 %) beyond the second-line. Eight (36.4 %) had an ECOG-performance status 1-2. Two partial responses (PR, ORR: 9.1 %), 7 stable disease (SD) and 11 PD were obtained. Median follow-up was 8.3 months (IQR: 7-10.3), 6-month progression-free survival (PFS) was 13.6 % (95%CI: 4.8-39.0). Two SD are still receiving treatment after 11.5 and 6.3 months. Median overall survival (OS) was not reached (6-month OS: 59.1 %, 95%CI: 41.7-83.7). Hb