Business Update & Financial Outlook

Continuing to advance our broader oncology program Clinical progress • • • KEYNOTE-756: Phase 3 trial met one of its dual primary endpoints of PCR for treatment of patients with high-risk early-stage ER+/HER2- breast cancer KEYNOTE-A18: Phase 3 trial met one of its primary endpoints of PFS for treatment of patients with high-risk locally advanced cervical cancer Promising data presented at ASCO: KEYNOTE-671: KEYTRUDA perioperative regimen reduced risk of disease recurrence, progression, or death by 42% in patients with resectable stage II, IIIA or IIIB NSCLC KEYNOTE-942: V9401 (INT) and KEYTRUDA reduced risk of distant metastasis or death by 65% in patients with stage III/IV melanoma following complete resection - Initiated Phase 3 trial for adjuvant treatment of high risk, stage II to IV melanoma MK-28702: Showed encouraging anti-tumor activity in patients with locally advanced or metastatic NSCLC Regulatory updates • PROpel: received FDA approval for Lynparza³ in combination with abiraterone and prednisone in patients with deleterious or suspected deleterious BRCA-mutated mCRPC KEYNOTE-966: sBLA for KEYTRUDA in combination with chemotherapy in patients with locally advanced unresectable or metastatic biliary tract cancer accepted for FDA review KEYNOTE-811: KEYTRUDA in combination with trastuzumab and chemotherapy showed significant improvement in PFS in 1L treatment of HER2- positive advanced gastric or GEJ adenocarcinoma in patients whose tumors were PD-L1 positive Received positive EMA opinion 1. In collaboration with Moderna 2. In collaboration with Kelun 3. In collaboration with AstraZeneca MERCK 22

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