Poster Highlighting Phase II Clinical Study of KN026 for HER2-expressing Advanced GC/GEJ Presented at 2022 ASCO

SUZHOU,China,June 6,2022 --Alphamab Oncology (stock code: 9966.HK) and CSPC Pharmaceutical Group Co.,Ltd. (stock code: 1093.HK) jointly announced that data from a phase II clinical study of KN026 (HER2 bispecific antibody) monotherapy in patients with previously treated,advanced HER2-expressing gastric or gastroesophageal junction cancers (GC/GEJ) were presented as a poster at the 2022 American Society of Clinical Oncology Annual Meeting (2022 ASCO) being held June 3 - 7.

Title: A phase II study evaluating KN026 monotherapy in patients with previously treated,advanced HER2-expressing gastric or gastroesophageal junction cancers

Abstract Number:4040

Poster Number:28

HER2 is expressed in a range of tumor types and is associated with tumor aggressiveness and poor prognosis. Outcomes of second or later-line treatments for patients with advanced GC/GEJ remain inferior,and there is a huge unmet need. KN026 is a novel HER2-targeted bispecific antibody. Here we present the preliminary results of a phase II clinical study evaluating KN026 monotherapy in patients with previously treated,advanced HER2-expressing GC/GEJ at 2022 ASCO.

This is a multicenter,open-label,two-cohort,phase II study,enrolling patients with advanced GC/GEJ who failed at least one prior line of standard treatment. High-level HER2 expression in cohort 1(IHC3+ or IHC 2+ /ISH+) ; Low-level HER2 in cohort 2 (IHC 2+ /ISH-,IHC 1+ or IHC 0/ISH-). The primary endpoints were ORR and DOR assessed by investigators per RECIST 1.1; secondary endpoints are PFS,OS and safety outcomes,etc.

As of October 29,2021,45 patients were enrolled,and 39 (25 in cohort 1 and 14 in cohort 2) were eligible for response evaluation. In Cohort 1,the ORR was 56% (95% CI: 35%-76%); the median DOR was 9.7 months (95% CI: 4.2-NE),the median PFS was 8.3 months (95% CI: 4.2-11.4),and the median OS was 16.3 months (95% CI: 11.0-NE); 14 patients in cohort 1 have progressed on the prior trastuzumab treatment,of whom the ORR was 50% (95% CI: 23%-77%) and the median DOR was 7.0 months (95% CI: 2.8- NE),the median PFS was 5.5 months (95% CI: 1.5-11.0),and the median OS was 14.9 months (95% CI: 11.0-NE). In Cohort 2,the ORR was 14% (95% CI: 2%-43%),the median DOR was 6.2 months (95% CI: 3.2-NE),and the median OS was 9.6 months (95% CI: 3.5-14.9).

All 45 enrolled patients were evaluable for safety,and TRAEs were observed in 37 (82%) patients. The most common TRAEs (any grade) were increased aspartate aminotransferase (12,27%),increased alanine aminotransferase (9,20%),rash (7,16%),anemia (7,16%) and infusion-related reactions (7,16%). Four patients reported five grade 3 TRAEs,including infusion-related reactions,renal hydrocele,ureteral stenosis,increased blood pressure,and abnormal hepatic function (one each). No grade 4 or 5 TRAE occurred.

KN026 monotherapy yielded promising efficacy in GC/GEJ patients with high-level HER2 expression,showed a modest efficacy comparable with the current second-line chemotherapy in GC/GEJ patients with low-level HER2 expression,and demonstrated a favorable safety profile.

About KN026

KN026 is an anti-HER2 bispecific antibody invented by Alphamab Oncology using the proprietary Fc-based heterodimer bispecific platform technology called CRIB (Charge Repulsion Induced Bispecific). KN026 can bind two non-overlapping epitopes of HER2 simultaneously,leading to a dual HER2 signal blockade. KN026 has demonstrated potentially equivalent efficacy compared with Trastuzumab and Pertuzumab in combination,and was superior to either single agent,such as increased binding affinity,as well as better tumor inhibition in HER2-positive tumor cell lines. Additionally,KN026 has also shown inhibitory effect on tumor cells with medium or low HER2 expression or Trastuzumab-resistant cell lines.

KN026 received IND approval from the National Medical Products Administration (NMPA) of China and U.S. Food and Drug Administration (FDA) in 2018. Currently,it is in multiple phase I/II clinical trials in China and phase I clinical trial in the United States. The results of Phase I clinical trials show KN026 has good safety,tolerance and potentially superior anti-tumor activity in HER2-positive breast cancer patients who progressed after multiple lines of anti-HER2 treatment.

In August 2021,the company entered an agreement with JMT-Bio,a wholly-owned subsidiary of CSPC Pharmaceutical Group Co.,Ltd. (stock code: 1093.HK),for the development and commercialization of KN026 in Mainland China. According to the terms of the agreement,JMT-Bio will obtain the exclusive license rights of KN026 for the development and commercialization in the indications of breast cancer and gastric or gastroesophageal junction cancers (GC/GEJ) in Mainland China (excluding Hong Kong,Macau and Taiwan).

About Alphamab Oncology

Alphamab Oncology is focusing on innovation,including discovery,development,production and commercialization of anti-tumor drugs. On December 12,2019,the Company was listed in the mainboard of Hong Kong Stock Exchange with stock code 9966.

Alphamab has a fully integrated proprietary biologics platforms in bi-specifics and protein engineering. Its highly differentiated in-house pipeline consists of tumor monoclonal antibodies,bispecific antibodies,and antibody-drug conjugates. Five products have advanced into phase I-III clinical trials in China,the United States,Japan and Australia and in November 2021,one of these products,the unique PD-L1 antibody for subcutaneous administration,Envafolimab,received marketing authorization from the Chinese National Medical Products Administration (NMPA) for the treatment of previously treated MSI-H/dMMR advanced solid tumors.

The Company also has state-of-the-art manufacturing capabilities designed and built to meet NMPA and EU/FDA's cGMP standards and a complete quality system which has passed the on-site inspection of a European Union qualified person. Alphamab Oncology is committed to building a global leading,multi-dimensional drug development and commercialization platform,focusing on multifunctional biological innovative drugs,and to benefit patients in China and around the world.

About CPSC

CPSC,listed on the Hong Kong Stock Exchange (stock code: 1093),was selected as a constituent stock of the Hang Sang Index in 2018 and was the first constituent stock in the pharmaceutical sector since the launch of the index. Currently,it is one of constituent stocks of Hang Seng Composite Index,Hang Seng Healthcare Index,Hang Seng Mainland Healthcare Index,Hang Seng Stock Connect Index,Hang Seng (Hong Kong-listed) 100 Index and Hang Seng China Enterprise Index. As of the date of this announcement,CPSC has total assets of more than RMB30billion and more than 23,000 employees. CSPC has a national top research and development team with research and development bases in Shijiazhuang,Shanghai,Beijing and the United States,focusing on the discovery,research and development of small molecule targeted drugs,nanodrugs,monoclonal antibody drugs,bispecific antibody drugs,antibody-drug conjugates，mRNA vaccines,small nucleic acid drugs and biological drugs in the immune field.