Patient-reported outcomes (PROs) in cisplatin-ineligible patients (pts) with locally advanced or metastatic urothelial cancer (la/mUC) treated with enfortumab vedotin (EV) alone or in combination with pembrolizumab (P) in the phase 1b/2 EV-103 Cohort K study.

439 Background: The EV-103 Cohort K trial evaluated 1L EV+P or EV alone (NCT03288545) in pts with la/mUC who were cisplatin-ineligible. EV+P showed a clinically meaningful objective response rate (64.5%; 95% CI, 52.7–75.1) with a manageable safety profile. Because la/mUC is associated with symptoms with a frequent impact on quality of life (QOL) and functioning (Mamtani et al. JCO 2021), we describe the impact of EV+P or EV alone on QOL and symptoms. Methods: In this open-label, Phase 1b/2 trial, cisplatin-ineligible pts with la/mUC were randomized 1:1 to EV+P or EV alone. For exploratory PRO endpoints, pts completed EORTC QLQ-C30 and the BPI-SF at baseline, weekly for cycles 1–3, and once every cycle for the remainder of treatment period. The PRO analysis set included only pts who were treated and completed the questionnaire at baseline. Mixed effect models for repeated measures (MMRM; least squares [LS] mean, standard error [SE]) not adjusted for multiplicity, estimated change vs baseline until Week 24; established thresholds (EORTC QLQ-C30: 10-point change; BPI-SF: 2-point change) were applied to determine clinically meaningful change. Results: Of the 76 pts treated with EV+P, 65 were included in the PRO analysis set. EORTC QLQ-C30 and BPI-SF were completed by 100% and 95%, respectively, at baseline; compliance rates were ≥84% for both instruments through Week 24. In the EORTC QLQ-C30 MMRM analyses, QOL was maintained through Week 24 for EV+P; functioning and symptom scores remained stable over time, with improvements in emotional functioning, pain and sleep disturbance vs observed baseline. In the EV+P arm, clinically meaningful reductions in pain were seen at Week 12 (-12.64 [3.208]) vs baseline and persisted through Week 24 (-13.20 [3.406]). In the BPI-SF MMRM analyses, worst and average pain, pain interference and severity consistently showed improved scores from Week 4–24 for EV+P; clinically meaningful change in worst pain was seen at Week 21 (-2.08 [0.361]). Similar completion and compliance rates were seen for the EV alone PRO analysis set (n=63). EV alone demonstrated clinically meaningful improvements in pain at Week 24 in the EORTC QLQ-C30 (-10.63 [4.110]) and consistent small-to-moderate improvements in the BPI worst and average pain, and pain severity (0.5–1.0 points). Sleep disturbances demonstrated improvement, and other symptom scales, QOL and functional domains remained stable. Conclusions: PRO data showed that EV+P in cisplatin-ineligible pts with la/mUC was associated with preservation or improvement of QOL, functioning, and symptoms. Improvement in pain was demonstrated consistently in both PRO instruments and treatment arms. These PRO data complement the clinical outcomes of EV+P in 1L cisplatin-ineligible pts with la/mUC. Clinical trial information: NCT03288545 .