KEYNOTE-937 Trial

[Slide 1] Phase 3 KEYNOTE-937 Study Design ADJUVANT THERAPY Key Eligibility Criteria Pembrolizumab 200 mg IV Q3W Age >18 years of age Confirmed HCC x1 year Treated until Complete radiological R 1:1 response after surgical disease recurrence, N 959 resection or local unacceptable ablation of HCC toxicity, intercurrent Placebo IV Q3W ECOG PS 0 -1 illness, or withdrawal Child-Pugh liver class A X 1 year Stratification factors Endpoints Region (Asia [not including Japan] vs non-Asia) Primary: RFS by BICR or pathology; OS Prior local therapy (resection vs ablation) Key secondary: DMFS by BICR or pathology, safety Risk of recurrence (intermediate vs high vs very high risk) AFP at initial diagnosis before resection or ablation (<200 ng/mL VS >200 ng/mL) AFP, alpha fetoprotein. BICR, blinded independent central review. RFS, recurrence-free survival. DMFS, distant metastasis-free survival. Risk of recurrence: Intermediate, solitary tumor >2 cm without microvascular invasion and not histologic grade 3 or 4; High, solitary tumor >2 cm with microvascular invasion or same size and histologic grade 3 or 4, or multiple tumors regardless of microvascular invasion or histologic grade; Very-high, single tumor or multiple tumors of any size with microvascular invasion ASCO Gastrointestinal Cancers Symposium --- [Slide 2] Recurrence-Free Survival Events, Median RFS HR (95% CI) n (%) (95% CI), mo P-value 100 Pembrolizumab 239 (50) 46.7 (35.6-53.3) 1.06 (0.88-1.26) 90 Placebo 237 (49) 45.5 (35.6-58.0) 0.719 80 70 60 RFS, % 50 24-mo rate 63% I 40 61% 48-mo rate 50% 30 50% 20 10 0 0 6 12 18 24 30 36 42 48 54 60 66 72 No. at Risk Time, months 476 391 343 311 290 263 221 181 135 50 2 1 0 483 400 346 305 278 264 218 162 116 49 3 0 0 Data cut-off date: Mar 20, 2025. RFS by blinded independent central review or pathology. ASCO Gastrointestinal Cancers Symposium

[Slide 1] Recurrence-Free Survival Events, Median RFS HR (95% CI) n (%) (95% CI), mo P-value 100 Pembrolizumab 239 (50) 46.7 (35.6-53.3) 1.06 (0.88-1.26) 90 Placebo 237 (49) 45.5 (35.6-58.0) P 0.719 80 70 60 RFS, % 50 24-mo rate 63% 40 61% 48-mo rate 50% 30 50% 20 10 0 0 6 12 18 24 30 36 42 48 54 60 66 72 Time, months No. at Risk 476 391 343 311 290 263 221 181 135 50 2 1 0 483 400 346 305 278 264 218 162 116 49 3 0 0 Data cut-off date: Mar 20, 2025. RFS by blinded independent central review or pathology.

[Slide 1] Recurrence-Free Survival Events, Median RFS HR (95% CI) n (%) (95% CI), mo P-value 100 Pembrolizumab 239 (50) 46.7 (35.6-53.3) 1.06 (0.88-1.26) 90 Placebo 237 (49) 45.5 (35.6-58.0) P 0.719 80 70 60 RFS, % 50 24-mo rate 63% I 40 61% 48-mo rate 50% 30 50% 20 10 0 0 6 12 18 24 30 36 42 48 54 60 66 72 Time, months No. at Risk 476 391 343 311 290 263 221 181 135 50 2 1 0 483 400 346 305 278 264 218 162 116 49 3 0 0 Data cut-off date: Mar 20, 2025. RFS by blinded independent central review or pathology. ASCO Gastrointestinal Cancers Symposium --- [Slide 2] Recurrence-Free Survival Events, Median RFS HR (95% CI) n (%) (95% CI), mo P-value 100 Pembrolizumab 239 (50) 46.7 (35.6-53.3) 1.06 (0.88-1.26) 90 Placebo 237 (49) 45.5 (35.6-58.0) P 0.719 80 70 60 RFS, % 50 24-mo rate 63% I 40 61% 48-mo rate 50% 30 50% 20 10 0 0 6 12 18 24 30 36 42 48 54 60 66 72 Time, months No. at Risk 476 391 343 311 290 263 221 181 135 50 2 1 0 483 400 346 305 278 264 218 162 116 49 3 0 0 Data cut-off date: Mar 20, 2025. RFS by blinded independent central review or pathology. ASCO Gastrointestinal Cancers Symposium

[Slide 1] Overall Survival Events, Median OS HR (95% CI) n (%) (95% CI), mo 100 Pembrolizumab 98 (21) NR (NR to NR) 1.08 (0.81-1.43) Placebo 98 (20) NR (NR to NR) 90 80 24-mo rate 90% 70 94% 48-mo rate 60 79% os, % 81% 50 40 30 20 10 0 0 6 12 18 24 30 36 42 48 54 60 66 72 No. at Risk Time, months 476 471 456 436 422 409 369 305 232 138 62 8 0 483 480 475 466 450 438 380 303 223 124 54 8 0 Data cut-off date: Mar 20, 2025. --- [Slide 2] Recurrence-Free Survival Events, Median RFS HR (95% CI) n (%) (95% CI), mo P-value 100 Pembrolizumab 239 (50) 46.7 (35.6-53.3) 1.06 (0.88-1.26) 90 Placebo 237 (49) 45.5 (35.6-58.0) P 0.719 80 70 60 RFS, % 50 24-mo rate 63% 40 61% 48-mo rate 50% 30 50% 20 10 0 0 6 12 18 24 30 36 42 48 54 60 66 72 Time, months No. at Risk 476 391 343 311 290 263 221 181 135 50 2 1 0 483 400 346 305 278 264 218 162 116 49 3 0 0 Data cut-off date: Mar 20, 2025. RFS by blinded independent central review or pathology. --- [Slide 3] ASCO Gastrointestinal Cancers Symposium Adjuvant pembrolizumab for participants with hepatocellular carcinoma and complete radiologic response after surgical resection or local ablation: the phase 3 KEYNOTE-937 study Stephen Lam Chan1, Mohamed Bouattour2, Thomas Yau³, Ann-Lii Cheng⁴, Yabing Guo⁵, Chuang Peng⁶, Do Young Kim7, Lipika Goyal⁸, Long-Bin Jeng⁹, Ming-Chin Yu10, Seung Woon Paik¹¹, Valeriy Breder¹², Robert CG Martin II¹³, Arndt Vogel¹⁴, Masatoshi Kudo¹⁵, Jimin Wu¹⁶, Usha Malhotra¹⁶, Abby B Siegel¹⁶, Josep M Uovet¹⁷, Ja Fan18 State Key Laboratory of Translational Oncology, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong, China; 2AP-HP, Hôpital Beaujon, Liver Cancer Unit, INSERM U1149, Centre de Recherche de l'Inflammation (CRI), Paris, France; The University of Hong Kong, Hong Kong, China; National Taiwan University Hospital and National Taiwan University Cancer Center, Taipei, Taiwan; Southern Medical University, Nanfang Hospital, Guangzhou Southern Medical University, Guangzhou, China; ®Hunan Provincial People's Hospital (The First Affiliated Hospital of Hunan Normal University), Changsha, Hunan Province, China; Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Korea; Bepartment of Medicine, Stanford School of Medicine, Palo Alto, CA USA; ©Organ Transplantation Center, China Medical University Hospital, Taichung, Taiwan; 10Department of General Surgery, Chang Gung Memorial Hospital and Chang Gung University, Taoyuan, Taiwan; 11Sungkyunkwan University School of Medicine, Seoul, Republic of Korea; 12N N Blokhin Russian Cancer Research Center, Moscow, Russia; 13The Hiram C Polk, Jr., MD Department of Surgery, Division of Surgical Oncology, University of Louisville School of Medicine, Louisville, KY, USA; 14Toronto General Hospital, Medical Oncology, UHN Princess Margaret Cancer Centre, Toronto, ON, Canada; 15Department of Gastroenterology and Hepatology, Kindai University Faculty of Medicine, Osaka, Japan; 16Merck and Co., Inc, Rahway, NJ USA; "Mount Sinai Liver Cancer Program, Division of Liver Diseases, Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA; Department of Liver Surgery and Transplantation, Key Laboratory of Carcinogenesis and Cancer Invasion (Ministry of Education), Liver Cancer Institute, Zhongshan Hospital, Fudan University, Shanghai, China ASCO Gastrointestinal #GI26 ASCO AMERICAN SOCIETY OF PRESENTED BY: Stephen Lam Chan, MD CLINICAL ONCOLOGY Cancers Symposium Presentation is property of the author and ASCO. Permission required for reuse, contact permissions@asco.org KNOWLEDGE CONQUERS CANCER --- [Slide 4] Phase 3 KEYNOTE-937 Study Design ADJUVANT THERAPY Key Eligibility Criteria Pembrolizumab 200 mg IV Q3W Age ≥18 years of age Confirmed HCC X 1 year Treated until Complete radiological R 1:1 response after surgical disease recurrence, N = 959 resection or local unacceptable ablation of HCC toxicity, intercurrent Placebo IV Q3W ECOG PS 0 -1 illness, or withdrawal Child-Pugh liver class A X 1 year Stratification factors Endpoints Region (Asia [not including Japan] VS non-Asia) Primary: RFS by BICR or pathology; OS Prior local therapy (resection VS ablation) Key secondary: DMFS by BICR or pathology, safety Risk of recurrence (intermediate VS high VS very high risk) AFP at initial diagnosis before resection or ablation (<200 ng/mL VS >200 ng/mL) AFP, alpha fetoprotein. BICR, blinded independent central review. RFS, recurrence-free survival. DMFS, distant metastasis-free survival. Risk of recurrence: Intermediate, solitary tumor >2 cm without microvascular invasion and not histologic grade 3 or 4; High, solitary tumor >2 cm with microvascular invasion or same size and histologic grade 3 or 4, or multiple tumors regardless of microvascular invasion or histologic grade; Very-high, single tumor or multiple tumors of any size with microvascular invasion --- [Slide 5] Recurrence-Free Survival Events, Median RFS HR (95% CI) n (%) (95% CI), mo P-value 100 Pembrolizumab 239 (50) 46.7 (35.6-53.3) 1.06 (0.88-1.26) 90 Placebo 237 (49) 45.5 (35.6-58.0) P 0.719 80 70 60 RFS, % 50 24-mo rate 63% 40 61% 48-mo rate 50% 30 50% 20 10 0 0 6 12 18 24 30 36 42 48 54 60 66 72 Time, months No. at Risk 476 391 343 311 290 263 221 181 135 50 2 1 0 483 400 346 305 278 264 218 162 116 49 3 0 0 Data cut-off date: Mar 20, 2025. RFS by blinded independent central review or pathology.

[Slide 1] Phase 3 KEYNOTE-937 Study Design ADJUVANT THERAPY Key Eligibility Criteria Age 218 years of age Pembrolizumab 200 mg IV Q3W Confirmed HCC X 1 year Treated until Complete radiological R 1:1 response after surgical disease recurrence, N - 253 resection or local unacceptable ablation of HCC toxicity, intercurrent ECOG PS 0-1 Placebo IV Q3W illness, or withdrawal Child-Pugh liver class A X 1 year Stratification factors Endpoints Region (Asia [not including Japan] vs non-Asia) Primary: RFS by BICR or pathology: os Prior local therapy (resection vs ablation) Key secondary: DMFS by BICR or pathology, safety Risk of recurrence (intermediate vs high vs very high risk) AFP at initial diagnosis before resection or ablation (<200 ng/mL vs >200 ng/mL) AFP. alpha fetoprotein. BICR, blinded independent central review RFS recurrence-tree survice DMFS, distant metastasis thee survival Risk of recurrence intermediate, solitary funor 22 on without microvascular invasion and not histologic grade 3 or 4. High, solitary numer 22 on with microvascular invasion or same - and histologic grade 3 or 4, or multiple funiors regardless of microvascular invasion or histologic grade, Very-high, single funior or multiple sumors of any size with microvascular invasion --- [Slide 2] Baseline Characteristics Pembrolizumab Placebo Pembrolizumab Placebo Characteristic, n (%) N 476 N 483 Characteristic, n (%) N 476 N 483 Median age (range), years 62 (25 85) 63 (27 85) Child Pugh score Male 375 (79) 384 (80) A5 442 (93) 435 (90) Race A6 33 (7) 48 (10) Asian 268 (56) 262 (54) Missing 1 (<1) 0 White 196 (41) 212 (44) Prior ablation Black 6(1) Yes 4(1) 61 (13) 62 (13) No Other*/Missing 6(1) 5(1) 415 (87) 421(87) Prior local therapy Geographic region Resection 421(88) 424(88) North America 19(4) 25(5) Ablation 55 (12) 59 (12) Western Europe 134(28) 125 (26) Recurrence risk group Rest of World 323(68) 333 (69) Intermediate 96(20) 103 (21) ECOG performance status High 350(74) 343 (71) 0 448 (94) 459 (95) Very high 30(6) 37 (8) 1 27(6) 24(5) BCLC stage Viral etiology A 394(83) 401 (83) HBV+ 287 (60) 286 (59) B 45(9) 41(8) HCV+ 117 (25) 101(21) C 37(8) 41(8) Alpha fetoprotein at initial diagnosis Microvascular invasion >200 ng/mL 91 (19) 97(20) Yes 273 (57) 279 (58) <200 ng/mL 368(77) 374(77) No 148 (31) 146 (30) Missing (4) 12(2) Not evaluated 55 (12) 58 (12) cut-off date: Mar 20, 2025. *Other includes participants of multiple races and Native American or other Pacific Islander. *Includes participants who had ablation and did not have available tissue and one ticipant who had resection and did not have HCC. BCLC, Barcelona Clinic Liver Cancer. --- [Slide 3] Recurrence-Free Survival in Key Subgroups Events/Patients, N Events/Patients, N Pembrolizumab Placebo HR (95% CI) Pembrolizumab Placebo HR (95% CI) Overall 239/476 237/483 1.06 (0.88-1.26) Overall 239/476 237/483 1.06 (0.88-1.26) Age, years Viral etiology <65 126/279 112/268 1.03 (0.79-1.32) Viral 160/343 164/341 0.93 (0.75-1.15) 265 113/197 125/215 1.03 (0.80-1.33) Non-viral 79/133 73/141 1.22 (0.89-1.68) Gender BCLC stage at initial diagnosis Female 54/101 40/99 1.43 (0.95-2.15) A 182/394 186/401 0.97 (0.79-1.19) Male 185/375 197/384 0.92 (0.75-1.13) B 30/45 29/41 0.79 (0.48-1.33) Race C 27/37 22/41 1.64 (0.93-2.88) White 123/196 119/212 1.20 (0.93-1.55) Child-Pugh score Non-White 114/277 118/269 0.87 (0.68-1.13) 5 215/442 205/435 1.00 (0.83-1.21) Geographic region 6 24/33 32/48 1.37 (0.81-2.32) Asia without Japan 81/207 Prior local therapy 86/197 0.82 (0.61-1.12) Non-Asia and Japan 158/269 Resection 203/421 193/424 151/286 1.16 (0.93-1.45) 1.05 (0.86-1.28) Ablation 36/55 44/59 AFP before resection or ablation 0.84 (0.54-1.30) HH Risk of Recurrence < 200 ing/mL 183/368 186/374 0.99 (0.81-1.21) 200 ng/nL Intermediate 44/96 56/103 45/91 1.03 (0.68-1.56) 0.75 (0.50-1.11) 44/97 HBV etiology High 170/350 160/343 1.03 (0.83-1.28) HBV+ 126/287 134/286 0.89 (0.70-1.14) Very High 25/30 21/37 2.01 (1.12-3.59) HBV- 113/189 103/196 Risk within local therapy subgroups 1.19 (0.91-1.55) Resection intermediate risk 26/65 31/68 HCV etiology 0.76 (0.45-1.29) Resection high-risk 155/329 144/322 HCV+ 63/117 1.05 (0.84-1.32) 61/101 0.76 (0.54-1.09) HCV- 176/359 176/382 I 1.08 (0.87-1.33) Resection very high-risk 22/27 18/34 2.14 (1.14-3.99) Ablation intermediate risk 18/31 25/35 0.78 (0.43-1.44) 0.1 1 10 0.1 1 10 Favors pembrolizumab Favors placebo Favors pembrolizumab Favors placebo Data cut-off date: Mar 20, 2025. RFS by blinded independent central review or pathology. --- [Slide 4] Overall Survival Events, Median OS HR (95% CI) n (%) (95% CI), mo 100 Pembrolizumab 98 (21) NR (NR to NR) 1.08 (0.81-1.43) Placebo 98 (20) NR (NR to NR) 90 80 24-mo rate 90% 70 94% 48-mo rate 60 79% OS, % 81% 50 40 30 20 10 0 0 6 12 18 24 30 36 42 48 54 60 66 72 No. at Risk Time, months 476 471 456 436 422 409 369 305 232 138 62 8 0 483 480 475 466 450 438 380 303 223 124 54 8 0 Data cut-off date: Mar 20, 2025.