The board of directors of SinoMab BioScience Limited announced that the National Medical Products Administration (the ``NMPA'') of the People's Republic of China (``PRC'') has accepted the biologics license application (``BLA'') for the Company's product, SM03 (Suciraslimab), in the treatment of rheumatoid arthritis (``RA'') (Acceptance No.: CXSS2300072). The application is the first market filing of the Company since its establishment. Suciraslimab is the Company's self-developed product and is a global first-in-target anti-CD22 monoclonal antibody for the treatment of RA and other immunological diseases, it adopts a novel mechanism of action unique to SM03, which differentiates itself from the current treatments available in the market.

The unblinded Phase III data revealed that Suciraslimab met its primary end point and achieved significant clinical efficacy for patients suffering from active rheumatoid arthritis, after 24-week period of double blinded treatment. In a 26-week open-label extension period, the company observed that the number of responders continued to increase. Subgroup analyses further identified patient population that responded favorably with Suciraslimab.

The clinical results were in agreement with the mechanism of action of Suciraslimab, which suggests that Suciraslimab acts on the more upstream process by preferentially targeting and suppressing pathogenic (autoreactive) B cells via the conversion of CD22 from a cis-binding configuration to a trans-binding configuration. The mechanism of action also explains why a superior safety profile was observed with Suciraslimab, as the normal functions of other protective B cells are left unperturbed. Detailed results of the clinical data and analyses will be reported as publications in medical journals.

RA is an autoimmune disease that causes chronic inflammation of the joints and other areas of the body. The inflammation causes tissues that line the inside of joints to thicken, resulting in swelling and pain in and around the joints. There is no permanent cure for RA, and patients require long term care to treat the symptoms.