Business Update & Financial Outlook

Driving value for patients and shareholders by progressing our pipeline Key regulatory milestones since the last earnings call: • In the U.S., the FDA: 。 Granted approval of Lynparza' in combination with abiraterone and prednisone in patients with deleterious or suspected deleterious BRCAM metastatic castration-resistant prostate cancer o Accepted sBLA for KEYTRUDA in combination with chemotherapy in patients with locally advanced unresectable or metastatic biliary tract cancer o Approved a new indication for PREVYMIS for prophylaxis of cytomegalovirus (CMV) disease in adult kidney transplant recipients at high risk ○ Accepted the re-submission of NDA for gefapixant in patients with refractory or unexplained chronic cough • In the EU, the EMA: o Accepted SMAA for KEYTRUDA in combination with trastuzumab and chemotherapy in patients with locally advanced unresectable or metastatic HER2-positive gastric or gastroesophageal junction adenocarcinoma o Received positive CHMP opinion for gefapixant in patients with refractory or unexplained chronic cough • In Japan, the PMDA: • 。 Granted approval of KEYTRUDA in patients with relapsed or refractory primary mediastinal B-cell lymphoma o Accepted sJNDA for KEYTRUDA in combination with chemotherapy in 1L treatment of locally advanced unresectable or metastatic gastric or gastroesophageal junction adenocarcinoma, as well as in patients with locally advanced unresectable or metastatic biliary tract cancer • Granted approval of VAXNEUVANCE in pediatrics In China, the CDE: 。 Granted approval of Koselugo¹ for the treatment of symptomatic, inoperable plexiform neurofibromas in pediatric patients with neurofibromatosis type I ages 3 years and older • • • • • Key data & clinical advancements since the last earnings call: Presented data across broad oncology portfolio at ASCO, including for KEYTRUDA (KN-671, KN-483, KN-581, KN-716, KN-826), Lenvima², Lynparza¹, WELIREG, mRNA-4157/V9403 (INT) and MK-2870/SKB2644 (TROP2 ADC) Announced positive topline results for KN-811 evaluating KEYTRUDA in combination with trastuzumab as 1L treatment in patients with HER2-positive advanced gastric or gastroesophageal junction adenocarcinoma in PD-L1 positive patients Announced Phase 3 KN-A18 trial met primary endpoint of progression-free survival in patients with newly diagnosed high-risk locally advanced cervical cancer Announced Phase 3 KN-756 trial met one of its dual primary endpoints of pathological complete response rate in patients with high-risk, early-stage ER+/HER2-breast cancer Presented Phase 2a data at EASL for efinopegdutide (MK-6024), an investigational GLP-1/glucagon receptor co-agonist, in patients with nonalcoholic fatty liver disease (NAFLD), which has advanced to Phase 2b in nonalcoholic steatohepatitis (NASH) Completed BLA submission of sotatercept for pulmonary arterial hypertension (PAH) to the FDA Announced positive topline results from two Phase 3 trials evaluating V116 in vaccine-naïve and previously vaccinated individuals 1. In collaboration with AstraZeneca 2. In collaboration with Eisai 3. In collaboration with Moderna 4. In collaboration with Kelun MERCK 21

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