1、Acquisition of Prometheus BiosciencesApril 17,2023Agenda2Rob DavisChairman&Chief Executive OfficerCaroline LitchfieldChief Financial OfficerStrategic Rationale|Rob DavisScientific Overview|Dean LiClinical Profile|Eliav BarrCommercial Opportunity|Chirfi GuindoFinancial Overview|Caroline LitchfieldQ&A

2、Dr.Eliav BarrSVP,Head of Global Clinical Development&Chief Medical OfficerChirfi GuindoChief Marketing Officer Human HealthDr.Dean LiPresident,Merck Research LaboratoriesImportant Information About the Transaction3Merck&Co.,Inc.(“Merck”),through a subsidiary,has agreed to acquire Prometheus Bioscien

3、ces,Inc.(“Prometheus Biosciences”).The acquisition is subject to Prometheus Biosciences shareholder approval.The closing of the transaction will be subject to certain conditions,including the expiration of the waiting period under the Hart-Scott-Rodino Antitrust Improvements Act and other customary

4、conditions.A copy of the merger agreement pursuant to the transaction will be filed with the Securities and Exchange Commission(“SEC”)and will be publicly available.In addition,Merck and Prometheus Biosciences file annual,quarterly and current reports and other information with the SEC,which are ava

5、ilable to the public from commercial document-retrieval services and at the SECs website at www.sec.gov.Copies of the documents filed with the SEC by Merck may be obtained at no charge on Mercks internet website at or by contacting Merck at 2025 E Scott Ave,Rahway,N.J.07033 or(908)423-1000.Copies of

6、 the documents filed with the SEC by Prometheus Biosciences may be obtained at no charge on Prometheus Biosciences internet website at or by contacting Prometheus Biosciences at 3050 Science Park Rd,San Diego,C.A.92037 or(858)824-0895.Forward-looking statement of Merck&Co.,Inc.,Rahway,N.J.,USA4This