The board of directors of Shanghai Henlius Biotech, Inc. announced that, recently, the first patient in the United States of America has been dosed in an international multicentre phase 3 clinical study comparing HANSIZHUANG (serplulimab injection) independently developed by the Company ("HANSIZHUANG") or placebo in combination with chemotherapy (carboplatin/cisplatin-etoposide) and concurrent radiotherapy for the treatment of limited-stage small cell lung cancer (LS-SCLC) patients. Clinical trial design and purpose: This randomised, double-blind, international multicentre, phase 3 clinical study aims to compare the efficacy and safety of HANSIZHUANG versus placebo, in combination with chemotherapy (carboplatin/cisplatin-etoposide) and concurrent radiotherapy in patients with limited-stage small cell lung cancer (LS-SCLC). Eligible patients will be randomised into two groups at a ratio of 1:1. The primary objective of this study is to evaluate the antitumour activity of HANSIZHUANG plus chemotherapy and concurrent radiotherapy in limited-stage small cell lung cancer (LS-SCLC) patients.

The primary endpoint is overall survival (OS). The secondary endpoints include progression-free survival (PFS), objective response rate (ORR), and duration of response (DOR) assessed by investigators per RECIST 1.1, as well as safety and immunogenicity. About HANSIZHUANG: HANSIZHUANG is an innovative anti-PD-1 monoclonal antibody independently developed by the Company and was approved for marketing in mainland China in March 2022.

As of the date of this announcement, HANSIZHUANG has been approved for two indications in mainland China: (1) the treatment of adult patients with advanced unresectable or metastatic Microsatellite Instability-High (" MSI-H ") solid tumours that have failed to respond to the standard therapy; and (2) the first-line treatment of patients with unresectable locally advanced or metastatic squamous non-small cell lung cancer (sqNSCLC) in combination with carboplatin and albumin-bound paclitaxel. In addition, the new drug applications for another two indications of HANSIZHUANG have been accepted by the National Medical Products Administration (the "NMPA"): in April 2022, the new drug application (NDA) of HANSIZHUANG in combination with chemotherapy for the first-line treatment of previously untreated patients with extensive stage small cell lung cancer (ES-SCLC) was accepted by the NMPA; in August 2022, the new drug application (NDA) of HANSIZHUANG in combination with chemotherapy for the first-line treatment of patients with locally advanced/recurrent or metastatic esophageal squamous cell carcinoma (ESCC) was accepted by the NMPA. HANSIZHUANG has been granted orphan-drug designations for the treatment of small cell lung cancer (SCLC) by the United States Food and Drug Administration (FDA) and the European Commission (EC) in April 2022 and December 2022, respectively.

In September 2022, the results of a phase 3 study of HANSIZHUANG in combination with chemotherapy as first-line treatment for patients with extensive stage small cell lung cancer (ES-SCLC) were published online in The Journal of American Medical Association (JAMA, impact factor of 157.3), one of the top four medical journals in the world. HANSIZHUANG is planned to be used for the treatment of a variety of solid tumours, and in addition to the indications of the MSI-H solid tumours and squamous non-small cell lung cancer (sqNSCLC) which have been approved for marketing, HANSIZHUANG is being undergone clinical studies in 11 combination therapies with it as the core in various countries and regions around the world. Market Condition: As of the date of this announcement, in addition to HANSIZHUANG of the Company, monoclonal antibody drugs targeting PD-1 that have been marketed globally include Keytruda® of Merck & Co.

Inc., Opdivo® of Bristol-Myers Squibb and Libtayo® of Regeneron Pharmaceuticals, Inc., etc. There is no monoclonal antibody drug targeting PD-1 or PD-L1 approved for the treatment of limited-stage small cell lung cancer (LS-SCLC) worldwide.