Background: In the randomized, double-blind, phase 3 KEYNOTE-394 trial (NCT03062358), pembro + BSC vs PBO + BSC as 2L therapy significantly reduced the risk of death by 21% (HR 0.79, 95% CI 0.63-0.99, P= 0.0180), prolonged PFS (HR 0.74, 95% CI 0.60-0.92, P= 0.0032), and improved ORR (estimated difference 11.4%, 95% CI 6.7-16.0, P= 0.00004) with a manageable safety profile in pts in Asia with advanced HCC and progression on or intolerance to sorafenib or oxaliplatin-based chemotherapy. Here we present the results of prespecified exploratory HRQoL analyses. Methods: EORTC QLQ-C30 and EuroQol-5D3L (EQ5D-3L) questionnaires were administered at baseline (BL); wks 3, 6, 9, 12, 18; every 9 wks thereafter up to 1 yr or end of treatment; at treatment discontinuation, and at the 30-day safety follow-up visit. Pts who received ≥1 dose of study treatment and completed ≥1 HRQoL assessment were included in the analyses. Least squares mean (LSM) score changes from BL to wk 12 were compared using a constrained longitudinal data analysis model, including treatment by study visit interaction and stratification factors as covariates. Kaplan-Meier method was used to estimate time to deterioration (TTD) (time to 1^st onset of ≥10-point decline from BL/confirmed by a 2^nd adjacent ≥10-point decline from BL) for EORTC QLQ-C30 global health status (GHS)/QoL. Stratified Cox proportional hazards model was used to assess the magnitude of the treatment difference (HR) between treatment arms in TTD with nominal, one-sided P value calculated. Results: The HRQoL population included 450 pts (298 pembro; 152 PBO). HRQoL compliance rate at wk 12 was 95.7% for pembro for both questionnaires and 94.4% for EORTC QLQ-C30 and 95.3% for EQ5D-3L for PBO. There was a statistically significant difference in LSM for change from BL to wk 12, between the two arms for the QLQ-C30 GHS/QoL score and EQ-5D VAS score, with more decline observed in the PBO arm. Difference in LSM for QLQ-C30 GHS/QoL score between pembro (-3.97; 95% CI, -6.38, -1.56) and PBO (-8.40; 95% CI, -11.71, -5.10) arms was 4.43 (95% CI, 0.47, 8.40; P= 0.0142). Difference in LSM for EQ-5D VAS score between pembro (-2.74; 95% CI, -4.51, -0.96) and PBO (-6.94; 95% CI, -9.40, -4.48) arms was 4.20 (95% CI, 1.21, 7.19; P= 0.0030). GHS/QOL mean scores generally remained stable over time in pembro arm. TTD in EORTC QLQ-C30 GHS/QoL score was similar between arms (HR, 0.85; 95% CI, 0.58, 1.25; P= 0.1993). Conclusions: Over 12 wks, pts treated with PBO + BSC showed more decline in HRQoL than those receiving pembro + BSC. Combined with the efficacy and safety results from KEYNOTE-394, as well as other global 2L trials with pembro, including KEYNOTE-240 and KEYNOTE-224, our data support the benefit of pembro as 2L therapy for pts with advanced HCC. Clinical trial information: NCT03062358.