VOLUNTARY ANNOUNCEMENTJACOBIO PRESENTED TWO CLINICAL DATA AT THE 2024 ASCO

Hong Kong Exchanges and Clearing Limited and The Stock Exchange of Hong Kong Limited take no responsibility for the contents of this announcement make no representation as to its accuracy or completeness and expressly disclaim any liability whatsoever for any loss howsoever arising from or in reliance upon the whole or any part of the contents of this announcement.JACOBIO PHARMACEUTICALS GROUP CO. LTD.加科思药业集团有限公司 (Incorporated in the Cayman Islands with limited liability) (Stock Code: 1167) VOLUNTARY ANNOUNCEMENT JACOBIO PRESENTED TWO CLINICAL DATA AT THE 2024 ASCO This announcement is made by JACOBIO PHARMACEUTICALS GROUP CO. LTD. (the “Company” or “Jacobio” together with its subsidiaries the “Group”) on a voluntary basis to inform the shareholders of the Company and potential investors about the latest business advancement of the Group.The board (the “Board”) of directors (the “Director(s)”) of the Company is pleased to announce that the Company presented the updated safety and efficiency data of a KRAS G12C inhibitor Glecirasib (JAB-21822) in combination with a SHP2 inhibitor (JAB-3312) in frontline non- small cell lung cancer (NSCLC) patients harboring KRAS G12C mutation at the 2024 American Society of Clinical Oncology (ASCO) Annual Meeting in the form of oral presentation. Jacobio also presented the updated data of registrational Phase II study of Glecirasib for the treatment of patients harboring advanced or metastatic NSCLC with KRAS G12C mutation in a second line setting in the form of oral presentation in an education session.As of April 7 2024 194 patients participated in a Phase II trial of using Glecirasib combined with JAB-3312 (NCT05288205) of which 102 patients had frontline NSCLC. The median follow-up time was 10.1 months and 58.8% (60/102) of patients remained on treatment.In the oral abstract session (Abstract No. 3008) Professor Jun Zhao a chief physician of Beijing Cancer Hospital the principal investigator of Glecirasib combined with JAB-3312 study presented the clinical data. About 102 frontline NSCLC patients have been enrolled in 7 dose groups. The confirmed objective response rate (cORR) was 64.7% (66/102) the disease control rate (DCR) was 93.1% (95/102) and the median progression-free survival (mPFS) was 12.2 months respectively. This trial explored a total of 7 different dose cohorts and the recommended Phase II optimal dose group was Glecirasib at 800mg daily combined with JAB-3312 at 2mg daily one week on and one week off. The cORR of the optimal dose group was 77.4% (24/31) and 54.8% (17/31) of patients achieved a deep response with tumors shrinking by more than 50%. The mPFS was not yet mature.Regarding on the safety data among the 194 patients the incidence of grade 3 or 4 treatment- related adverse events (TRAE) was 43.8% and there was no treatment-related death. Common TRAEs events include anemia hypertriglyceridemia etc. The safety profile in the frontline NSCLC patients is similar to that of the overall study population and the overall safety is manageable.The combination therapy of Glecirasib and JAB-3312 is being tested in a Phase III clinical trial of frontline NSCLC with KRAS G12C mutation in China. 1The new drug application (NDA) of Glecirasib monotherapy for the second-line NSCLC with KRAS G12C mutation was granted Priority Review designation by the Center for Drug Evaluation (CDE) of the National Medical Products Administration (NMPA) of China on May 21 2024. In the education session of ASCO Professor Yuankai Shi chief physician of Cancer Hospital Chinese Academy of Medical Sciences updated the data of the Phase II registrational trial of NSCLC with KRAS G12C mutation in an oral presentation.About Glecirasib Glecirasib (JAB-21822) is a KRAS G12C inhibitor independently developed by Jacobio. A number of Phase I/II clinical trials of Glecirasib are currently ongoing in China the United States and Europe for patients with advanced solid tumors harboring KRAS G12C mutation. These include a pivotal clinical trial in NSCLC in China a monotherapy study for STK11 co-mutated NSCLC in the front-line setting combination therapy trials with SHP2 inhibitor JAB-3312 in NSCLC and with cetuximab in colorectal cancer and a registrational pivotal clinical trial of single drug treatment for pancreatic cancer. The pancreatic cancer indication has obtained orphan drug designation in the United States and breakthrough therapy designation in China.About JAB-3312 JAB-3312 is a highly selective SHP2 allosteric inhibitor with best-in-class potential. Jacobio is currently conducting multiple clinical trials of JAB-3312 in China the United States and Europe including the combination therapy trial with Glecirasib. The Phase III study in combination with KRAS G12C inhibitor Glecirasib has been approved in China in February 2024.About Jacobio Jacobio is committed to developing and providing new and innovative products and solutions to improve patients’ health. Our pipeline revolves around novel molecular targets on six major signaling pathways: KRAS immune checkpoints tumor metabolism P53 RB and MYC. We aim for our key projects to be among the top three in the world. Our vision is to become a global leader recognized for our impact in drug R&D together with our partners. Jacobio has R&D centers in Beijing Shanghai and Boston with our Induced Allosteric Drug Discovery Platform (IADDP) and our immunostimulatory antibody-drug conjugate (iADC) Platform.Warning under Rule 18A.05 of the Rules Governing the Listing of Securities on The Stock Exchange of Hong Kong Limited: There is no assurance that Glecirasib (JAB-21822) and JAB- 3312 will ultimately be successfully developed and marketed by the Company. Shareholders of the Company and potential investors are advised to exercise caution when dealing in the shares of the Company. Please visit www.jacobiopharma.com for more information.By Order of the Board JACOBIO PHARMACEUTICALS GROUP CO. LTD.Yinxiang WANG Chairman Hong Kong June 2 2024 As at the date of this announcement the Board comprises Dr. Yinxiang WANG as Chairman and executive Director Ms. Xiaojie WANG and Ms. Yunyan HU as executive Directors Ms. Yanmin TANG and Dr. Te-li CHEN as non-executive Directors and Dr. Ruilin SONG Dr. Bai LU and Dr.Ge WU as independent non-executive Directors. 2