Background: T is recently approved in the US for treatment of advanced LMS or LPS after prior chemotherapy failure based on results from a randomized, phase-3 study (Demetri et al, 2015, J Clin Oncol; 62.4734). Here we describe patient-reported outcomes from this pivotal study, performed at the time of final progression-free survival and overall response rate analyses (interim overall survival analysis). Methods: Patients (pts) completed the M. D. Anderson Symptom Inventory (MDASI), a 19-item questionnaire that measures symptom severity (SS), and whether symptoms interfere with daily function (Symptom Interference-SI). Pts rated their experience (on 0-10 point scales, where lower scores mean fewer symptoms and less interference) across 13 different symptom measures (SS), and 6 measures of physical and mental function (SI), before treatment on day 1 of each treatment cycle (Cy). Results: Among 495 (T = 340; D = 155) pts randomized and treated, 329 (96.8%) from T group and 150 (96.8%) from D group completed baseline MDASI; compliance at each treatment Cy was high (91.4-100% [T] vs. 92.6-100% [D]). 72 pts on T and 14 on D received at least 8 Cy, and 71 (98.6%) pts (T) and 14 (100%) pts (D) completed questionnaires at Cy 8. Baseline MDASI scores for all measured symptoms were low and comparable across T and D groups (median range: 0-2.0). Pts’ experience with 3 core MDASI items (pain, fatigue, nausea) were representative of other SS measures with comparable mean baselines scores for both groups. Mean changes from baseline to Cy 8 in SS measures were not clinically meaningful for either group. Severe symptoms ( ≥ 7 on 0-10 scale) at baseline were reported most frequently in the pain (T: 15.9%, D:17.3%) and fatigue (T:13.4%, D: 16.7%) scores. The only statistically significant between-group difference was observed for nausea, and only at Cy 2 (9.4% [T] vs. 3.3% [D], p = 0.0396). Conclusions: Pts enrolled on this study had a relatively low baseline symptom burden. Symptom burden, assessed by MDASI, was generally not affected by drug treatment. Comparable side effects between treatment groups coupled with an improvement in efficacy supports T over D. Clinical trial information: NCT01343277