Background KEYNOTE-181 (NCT02564263) was an open-label, randomized, phase 3 trial of pembrolizumab (pembro) vs investigator choice of single-agent paclitaxel/docetaxel/irinotecan (chemo) in advanced/metastatic esophageal AC or SCC. Pts were enrolled in partially overlapping periods, initially globally and then in China with an extension period. We present results from the global and China cohorts. Methods Pts were randomized 1:1 to receive pembro or chemo. Randomization was stratified by histology (SCC vs AC) and region (Asia vs rest of world). Primary end points were OS in the ITT, SCC, and PD-L1 CPS ≥10 populations. Results There were 628 and 123 pts in the global and China cohorts, respectively. In the global cohort, 314 pts were randomized to receive pembro (199 [63%] had SCC; 107 [34%] had CPS ≥10 tumors); 314 pts to chemo (204 [65%] had SCC; 115 [37%] had CPS ≥10 tumors). Median follow-up was 7.1 mo (pembro) vs 6.9 mo (chemo). Median OS with pembro vs chemo was similar in the ITT group (7.1 vs 7.1 mo) and longer in the SCC (8.2 vs 7.1 mo) and CPS ≥10 groups (9.3 vs 6.7 mo). 12-month OS rates were higher with pembro in all groups (ITT 32% vs 24%; SCC 39% vs 25%; CPS ≥10 42% vs 20%). In the China cohort, 62 pts were randomized to pembro (60 had SCC; 25 had CPS ≥10 tumors); and 61 pts to chemo (59 had SCC; 29 had CPS ≥10 tumors). Median follow-up was 8.3 mo (pembro) vs 5.6 mo (chemo). Median OS was higher with pembro in the ITT (8.4 vs 5.6 mo; HR 0.55; 95% CI 0.36-0.82), SCC (8.4 vs 5.6 mo; HR 0.55; 95% CI 0.37-0.83), and CPS ≥10 groups (12.0 vs 5.3 mo; HR 0.34; 95% CI 0.17-0.69). 12-month OS rates were higher with pembro in all groups (ITT 36% vs 17%; SCC 36% vs 16%; CPS ≥10 53% vs 16%). Fewer pts had TRAEs with pembro than chemo (global 64% vs 86%; China 76% vs 83%). TRAE rates resulting in discontinuation with pembro vs chemo were comparable in the global cohort (6% each) and lower with pembro in the China cohort (6% vs 12%). Conclusions Pembro and chemo showed comparable OS as 2L therapy for esophageal AC/SCC in the global ITT cohort. Pembro showed favorable OS in SCC and CPS ≥10 groups in the global cohort and in all groups in the China cohort, in which most patients had SCC. Pembro showed favorable safety in both cohorts. Clinical trial identification NCT02564263. Editorial acknowledgement Medical writing and/or editorial assistance was provided by Traci Stuve, MA, of the ApotheCom pembrolizumab team (Yardley, PA, USA). This assistance was funded by Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, NJ, USA. Legal entity responsible for the study Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, NJ, USA. Funding Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, NJ, USA. Disclosure S-B. Kim: Research grant / Funding (institution): Novartis; Research grant / Funding (institution): Sanofi-Aventis; Research grant / Funding (institution): Kyowa-Kirin; Research grant / Funding (institution): DongKook Pharmaceutical. T. Doi: Advisory / Consultancy: Kyowa Hakko Kirin, MSD, Daiichi Sankyo, Amgen, Sumitomo Dainippon, Taiho Pharmaceutical, Takeda, AbbVie, Novartis, Bayer; Research grant / Funding (institution): Taiho Pharmaceutical, Novartis, Merck Serono, MSD, Boehringer Ingelheim, Pfizer, Lilly Japan, Sumitomo Group, Kyowa Hakko Kirin, Daiichi Sankyo, Bristol-Myers Squibb, AbbVie, Quintiles, Eisai. K. Kato: Research grant / Funding (institution): MSD, ONO Pharmaceutical, Shionogi, Merck Serono. M. Shah: Research grant / Funding (institution): Merck, Roche, Boston Biomedical. A. Adenis: Honoraria (self), Advisory / Consultancy, Speaker Bureau / Expert testimony, Research grant / Funding (institution), Travel / Accommodation / Expenses: MSD; Honoraria (self), Advisory / Consultancy, Speaker Bureau / Expert testimony, Research grant / Funding (institution), Travel / Accommodation / Expenses: BMS; Research grant / Funding (institution), Travel / Accommodation / Expenses: Bayer; Honoraria (self), Advisory / Consultancy, Speaker Bureau / Expert testimony: Servier. T. Kojima: Non-remunerated activity/ies, Other- Patents, Royalties, other Intellectual Property: Ono Pharmaceutical, MSD, Shionogi Pharma, Oncolys BioPharma, Astellas Amgen BioPharama; Honoraria (self): Oncolys BioPharma. J-P. Metges: Research grant / Funding (institution): Bristol-Myers Squibb; Research grant / Funding (institution): Merck; Honoraria (self): Bayer-Health; Honoraria (self): Lilly; Advisory / Consultancy: ERYTECH Pharma; Advisory / Consultancy: Sanofi. E. Francois: Research grant / Funding (institution): MSD; Non-remunerated activity/ies, +Personal Fees: Roche; Non-remunerated activity/ies, +Personal Fees: Servier; Non-remunerated activity/ies, +Personal Fees: Merck; Non-remunerated activity/ies, +Personal Fees: Amgen; Non-remunerated activity/ies, +Personal Fees: Sanofi; Non-remunerated activity/ies, +Personal Fees: Novartis; Non-remunerated activity/ies, +Personal Fees: Bayer. K. Muro: Honoraria (self): Takeda, Chugai Pharma, Yakult Honsha, Merck Serono, Taiho Pharmaceutical, Lilly, Ono Pharmaceutical, Bayer; Research grant / Funding (institution): Ono Pharmaceutical, MSD, Daiichi Sankyo, Shionogi, Kyowa Hakko Kirin, Gilead Sciences, Merck Serono, Pfizer, Sanofi. R. Wang: Full / Part-time employment: Merck & Co., Inc. Y. Cui: Full / Part-time employment: MSD China. P. Bhagia: Full / Part-time employment: Merck & Co., Inc. All other authors have declared no conflicts of interest.