AsSustained Hepatitis B Surface Antigen Loss in Chronic Hepatitis B Patients with Subcutaneous PD-L1 Antibody ASC22 Treatment: Interim Results of Phase IIb Study

Ascletis Pharma Inc. (HKEX: 1672) announces today that the interim results of 44 chronic hepatitis B (CHB) patients from a Phase IIb trial of ASC22 (Envafolimab), a subcutaneously administered PD-L1 antibody (ClinicalTrials.gov Identifier: NCT04465890), demonstrated sustained HBsAg loss in CHB patients with baseline HBsAg ≤ 500 IU/mL. The result abstract has been selected for oral presentation in Late Breaking Session at The Liver Meeting® 2021 by the American Association for the Study of Liver Diseases (AASLD), which has to be of sufficient scientific importance and high impact to meet the criteria of Late-Breaking Abstract of The Liver Meeting®.

The Phase IIb study is a randomized, single-blind, placebo-controlled, multi-center clinical trial in China which evaluates the efficacy and safety of treating CHB patients for 24-week treatment of 1 mg/kg or 2.5 mg/kg ASC22 or matching placebo given once every two weeks (Q2W) in combination with NAs.

"ASC22 is the earliest and most advanced clinical stage immunotherapy in the world for CHB functional cure, i.e. HBsAg loss, through blocking PD-1/PD-L1 pathway. Been selected for oral Late Breaking presentation indicates close attention by the committee of The Liver Meeting® 2021 to the study." said Professor Guiqiang Wang, director of infectious diseases department and liver disease center of Peking University First Hospital, president of eleventh committee, Society of Infectious Diseases, Chinese Medical Association, and principal investigator of the Phase IIb trial.

"There are unremitting efforts by scientists all over the world to cure CHB. However, HBsAg loss is difficult to achieve. We are excited to see ASC22 as an immunotherapy play a fundamental role in functional cure of CHB patients. The percentage of patients with baseline HBsAg lower than 500 IU/mL is as high as 30% of all CHB patients. With such exciting interim data, we are on track to advance into the registration trials as planned." said Dr. Jinzi J. Wu, Founder, Chairman and CEO of Ascletis.

Abstract to be presented is as follow:

HBsAg LOSS IN CHRONIC HEPATITIS B PATIENTS WITH SUBCUTANEOUS PD-L1 ANTIBODY ASC22 (ENVAFOLIMAB) PLUS NUCLEOS(T)IDE ANALOGS TREATMENT: INTERIM RESULTS FROM A PHASE IIb CLINICAL TRIAL

• Presentation Type: Oral, Parallel Session

• Publication Number: LO12

• Session Title: Late Breaking Session 2

• Presenting Author: Dr. Jinzi J. Wu, Ascletis BioScience Co., Ltd.

• Session Broadcast Date and Time: Monday, November 15, 2021, 12:30-02:00 PM EST

About Ascletis

Ascletis is an innovative R&D driven biotech listed on the Hong Kong, S.A.R., China Stock Exchange (1672.HK), a global platform covering the entire value chain from discovery and development to manufacturing and commercialization. Ascletis is committed to developing and commercializing innovative drugs in the areas of viral diseases, NASH/PBC, and cancer (oral cancer metabolic checkpoint and immune checkpoint inhibitors) to address unmet medical needs both in China and globally. Led by a management team with deep expertise and a proven track record, Ascletis targets those therapeutic areas with unmet medical needs from a global perspective, and efficiently advances the developments of pipelines with an aim of leading in global competition. To date, Ascletis has three marketed products and 18 robust R&D pipelines of drug candidates with global competitiveness, and is actively exploring new therapeutic areas.

1. Viral Diseases: (1) Hepatitis B Virus (functional cure): focus on breakthrough therapies for CHB functional cure with a subcutaneously-injected PD-L1 antibody – ASC22 and Pegasys® as cornerstone drugs. (2) HIV/AIDS: ASC22, an immune therapy to restore HIV-specific immune responses and eventually lead to a functional cure of HIV-infected patients. (3) Hepatitis C: successfully launched an all-oral regimen of combining ASCLEVIR® and GANOVO® (RDV/DNV regimen).      2. Non-alcoholic Steatohepatitis/Primary Biliary Cholangitis: Gannex, a wholly-owned company of Ascletis, is dedicated to the R&D and commercialization of new drugs in the field of NASH. Gannex has three clinical stage drug candidates against three different targets – FASN, THRβ and FXR, three fixed-dose combinations for NASH and one PBC program targeting FXR. 3. Cancer (oral cancer metabolic checkpoint and immune checkpoint inhibitors): a pipeline of oral inhibitors targeting FASN, which plays a key role in cancer lipid metabolism, and a pipeline of oral PD-L1 small molecule next generation immune checkpoint inhibitors. 4. Exploratory Indications: Acne: Following NASH and recurrent GBM, the third indication for ASC40 has been approved to enter Phase 2 clinical trial.

Source: Ascletis Pharma Inc.