Background: The randomized phase 3 TIVO-3 study met the primary endpoint of improved PFS with tivozanib (TIVO) vs sorafenib (SOR) in patients with relapsed/refractory mRCC with fewer dose reductions, interruptions and discontinuations despite a longer time on therapy. Greater insight into temporal characteristics of treatment-emergent adverse events (TEAEs) may enable proactive supportive care strategies and improve patient experience. Methods: Updated safety from the previously reported TIVO-3 study with a data cutoff August 15, 2019, was analyzed by treatment arm for time-to-onset (TTO, days [d]) of the most commonly reported TEAEs, and TTO of first dose reduction, interruption, and discontinuation occurring with TIVO and SOR. Duration of TEAE (median d and IQ range), and rate of dose reduction, interruption, or discontinuation due to the TEAE was calculated for each arm. Results: Patients in the safety analysis randomly assigned to TIVO (n = 173) or SOR (n = 170) received 11.9 and 6.7 cycles, or 336 and 192 mean days of treatment exposure, respectively. Incidence of any Gr, Gr >3, and TTO of any Gr TEAE of special interest occurring with >20% frequency in either arm is shown in Table 1. While TIVO was associated with less Gr>3 diarrhea, rash and PPE and more HTN than SOR, there were few differences in the TTO or duration of these TEAEs. Overall, dose reductions, interruptions, and discontinuations due to TEAEs were less frequent with TIVO than SOR, and TTO of first dose reduction (85 vs 45 d), interruption (81 vs 50 d), and discontinuation (114 vs 49 d) was longer for TIVO than SOR. Among those experiencing the same TEAE in either arm, resulting dose modifications were less frequent with TIVO than SOR. Conclusions: TIVO-3 demonstrated improved PFS with TIVO compared to SOR in mRCC, with longer duration of TIVO exposure, but fewer all Gr and Gr >3 TEAEs. Temporal characteristics of TEAEs were similar, but time to dose modifications was longer with TIVO than SOR. Among those with the same TEAEs, unmodified treatment was continued more often with TIVO than SOR. Clinical trial information: NCT02627963

*Proportion of patients with TEAE that resulted in study drug dose interruption, reduction, or discontinuation.