On July 3, 2023, the Class I innovative drug "Recombinant human coagulation factor IX-Fc fusion protein for injection" (SS327) independently developed by Gensciences received the notice of clinical trial approval from the National Medical Products Administration. The clinical trial will be conducted in adolescents over 12 years of age and adults with hemophilia B (congenital factor IX deficiency).

Hemophilia B is an X-chromosome-linked recessive disorder. Almost all patients with hemophilia B are males, while females are extremely rare, with an incidence of about 1/25000 in newborn boys. Its clinical manifestations are mainly joint, muscle and deep tissue bleeding. Repeated bleeding without prompt treatment may lead to joint deformity and/or pseudotumor, and it may be life-threatening in severe cases.

Currently, hemophilia B is mainly treated clinically by FIX replacement therapy, i.e., FIX is infused to restore the level of coagulation factor FIX in the patient's plasma to achieve a therapeutic effect. However, there is currently an extreme shortage of FⅨ products in China, with only three products available on the market, that is, Taijiuan® (Shandong Taibang, a blood-derived product), BeneFix® (Pfizer, regular half-life recombinant FⅨ), and Alprolix® (Sanofi, long-acting recombinant FⅨ). Although Alprolix® was approved for marketing in China in 2021 as an “urgently needed clinical drug”, it has not yet been included in the scope of medical insurance and officially put on the market. There are no domestic recombinant FIX products on the market, and the clinical needs of hemophilia B patients in China are far from being met.

As a result, there are fewer drug options available for hemophilia B patients in China, and they also face significant financial pressures due to the high price and health insurance reimbursement limitations of the marketed products. The high price of FIX products has led to a very low percentage of hemophilia B patients using FIX products for prophylaxis.

SS327 significantly extends the in vivo half-life of factor IX based on its original PEG fusion and Fc fusion technology. According to preclinical head-to-head data, SS327 has a half-life much longer than the existing factor IX products on the market worldwide. Moreover, SS327 is expected to significantly lower the economic burden of patients and greatly improve the product accessibility. When SS327 is put on the market in the future, it is expected to break the monopoly of imported recombinant factor IX products and fill the blank of domestic recombinant factor IX products. It is expected to gradually improve the therapeutic status of hemophilia B patients in China from drug shortage to prophylaxis medication, improve their compliance, and lower the economic burden of their families as well as the society, demonstrating great social significance.