Excelmab Files IPO Prospectus: Pioneering Best-in-Class Bispecific Antibody Therapies with Proprietary ExMab® Platform
From radiotherapy and chemotherapy to targeted therapies, and from small molecules to biological macromolecules, human strategies against cancer have undergone multiple iterations. The only constant has been the pursuit of drug efficacy and safety. Currently, the most cutting-edge anti-cancer strategy is undoubtedly tumor immunotherapy, which not only reactivates the body’s own immune system to attack tumors but also “precisely guides” treatments to lock onto specific types of tumors based on particular targets. However, tumorigenesis is often not controlled by a single gene; rather, it results from the combined effects of multiple genes accompanied by high mutational burden.
Unlike small molecules and monoclonal antibodies, which target a single tumor-specific antigen, bispecific antibodies (BsAbs) enable dual binding to either a “tumor target” and an “immune target,” or two “immune targets.” This approach fundamentally blocks tumor expansion by interfering with tumor escape mechanisms, providing a dual safeguard for tackling complex and heterogeneous malignant tumors.
Compared with traditional monoclonal antibodies or emerging cell therapies, bispecific antibodies offer greater advantages in terms of cost, treatment efficacy, and side effects, and their applicability is not limited to individual patients. Bispecific antibody drugs that have undergone certain modifications can more effectively reduce cytokine storm, exhibiting lower toxicity and higher safety.
Dr. Zhang Wenjun has long been dedicated to the research and development of bispecific antibodies for tumor immunotherapy, boasting 18 years of experience in antibody R&D at major U.S. pharmaceutical companies. He has previously held positions at renowned multinational pharmaceutical corporations, including Novartis, Tanox, AstraZeneca/MedImmune, Macrogenics, and BMS. Dr. Zhang led the development of multiple bispecific antibody candidates in clinical trials abroad and contributed to the development of one approved bispecific antibody and several approved monoclonal antibodies in the United States.
Dr. Zhang Wenjun, Founder of AI Simai Biotech
“I am highly optimistic about the future development of bispecific antibodies. My early R&D experience has shown me that bispecific antibodies deliver superior efficacy compared to monoclonal antibodies, and even outperform combination therapies involving monoclonal antibodies. This therapeutic advantage is particularly pronounced in tumor immunotherapy. Driven by the rapid advancement of China’s biopharmaceutical industry and investment interest extended to us, I made the decisive choice to return to China to pursue the R&D and industrialization of bispecific antibodies,” stated Dr. Zhang Wenjun.
In 2016, Dr. Zhang Wenjun founded Guangzhou AI Simai Biomedical Technology Co., Ltd. (hereinafter referred to as “AI Simai Bio”), a technology-driven enterprise dedicated to the research and development of Class I innovative drugs in the field of tumor immunology. The company was established with the original intention of developing affordable “Chinese specialty drugs” accessible to the general public, thereby providing better treatment options for patients in China.
“The current limitations on the development of bispecific antibody drugs mainly stem from two aspects: toxicity issues and challenges in large-scale purification processes,” Dr. Zhang Wenjun told VCBeat. Guangzhou AI Simai Biomedical Technology Co., Ltd. applies its domestically exclusive IgG dual-engineering technology, ExMab®, to fuse two antibody molecules with different specificities. This approach minimizes structural modifications to the IgG framework while ensuring bispecific functionality, thereby reducing immunogenicity to the lowest possible level and resulting in a stable innovative therapeutic agent.
“After multiple rounds of antibody engineering, we have controlled the occurrence of cytokine storms while maintaining molecular efficacy. Furthermore, charge engineering at the Fc region enables high yields, with heterodimer expression rates exceeding 95%,” added Dr. Zhang Wenjun. “Our purification process is straightforward and compatible with standard monoclonal antibody manufacturing workflows, thereby meeting the demands of large-scale production. This positions our platform ahead of other similar technologies currently available on the market.”
In terms of manufacturing processes, AI Simai Biomedical has implemented corresponding modifications and upgrades to both the Fab and Fc fragments. The related technologies have been granted patents in several leading biopharmaceutical countries, including the United States, Japan, South Korea, and Australia. These innovations help reduce the issue of four-chain mispairing at the Fab end and increase yield. Furthermore, the company has established an antibody discovery platform with multiple sources and ultra-high capacity, which can generate a variety of candidate antibodies that meet clinical therapeutic applications after undergoing a series of rigorous validation steps.
As a bispecific antibody developer, how can one “catch big fish” in a limited pool? This is a key challenge in the bispecific antibody R&D market. According to Li Feng, Senior Director at Guangzhou AI Simai Biomedical Technology Co., Ltd., “The scope for modifying large-molecule compounds is limited. Companies must both circumvent patent barriers and identify new avenues for innovation, which is no easy feat. Rather than relying on established technologies, we have pioneered an entirely new approach to fundamentally address the challenges of developing bispecific antibodies into viable drugs.”
EX101, developed through Aismile Biologics’ proprietary novel bispecific antibody drug platform, ExMab®, can effectively improve the tumor immune microenvironment, significantly enhance tumor-killing efficiency, and reduce toxic side effects. Preclinical studies currently underway indicate that EX101 exhibits lower immunogenicity and high stability, with molecular engineering significantly reducing cytokine release syndrome. Its maximum tolerated dose in cynomolgus monkeys is substantially higher than that of similar molecules domestically and internationally.
Since its establishment, Guangzhou AI Simai Biomedical Technology Co., Ltd. has assembled a highly efficient and professional R&D team, as well as an experienced management team. Throughout the drug development process, each project is led by researchers with strong technical expertise and extensive R&D experience, ensuring the quality and efficiency of project advancement. Meanwhile, senior managers oversee key aspects such as project management, clinical trial applications, and drug registration. The entire team collaborates efficiently, exercising strong execution capabilities to maintain comprehensive control over the entire process from drug development to final market launch.
Regarding expectations for the company’s future vision, Dr. Zhang Wenjun stated, “Our company remains committed to innovation as its core driver. By integrating technological and resource advantages from China and the United States, we aim to rapidly evolve into a global enterprise. We hope to address various solid tumors, hematologic malignancies, and viral infections through immune system reactivation, modulation of the immune microenvironment, and reversal of immunosuppression, thereby providing solutions for sudden global disease outbreaks.”
It is reported that AI Simai Biomedical completed a tens-of-millions-yuan Series A+ financing round this March, with investors including KIP Capital (Korea Investment Partners), Guoke ChanTou, Mifang Capital, and Caijin Capital. Regarding the investment in AI Simai Biomedical, Fu Hao, VP of KIP Capital, stated, “The founding team of AI Simai has extensive R&D experience in the field of bispecific antibodies. Leveraging its fully proprietary bispecific antibody structure platform, the company has accumulated a rich product pipeline within just two to three years of establishment, demonstrating high R&D efficiency. Meanwhile, the preliminary preclinical results of the company’s products are highly encouraging, and they are poised to enter clinical stages soon. We are optimistic about the company’s R&D strategy and execution capabilities in the bispecific antibody sector and wish AI Simai rapid growth into a new key player in China’s bispecific antibody landscape.”