The phase III clinical trial of REC603 in China consists of three parts, i.e. the efficacy trial, the immuno-bridging trial in younger-age groups, and the immunogenicity comparative trial with Gardasil^® 9, with a multi-center, randomized, blinded and parallel controlled design and with a total size of 16,050 subjects:

• Efficacy trial: To evaluate the protective efficacy of the vaccines in healthy female subjects aged 18 to 45 against high-risk HPV infection-related high-grade cervical, vulvar, vaginal high-grade intraepithelial neoplasia and above lesions.
• Immuno-bridging trial in younger-age groups: To evaluate the non-inferiority of serum virus neutralizing antibodies in healthy female subjects aged 9 to 17 as compared with healthy female subjects aged 18 to 45 at one month after full-course vaccination with the experimental vaccines.
• Immunogenicity comparative trial with Gardasil^® 9: To evaluate the non-inferiority of serum virus neutralizing antibodies in healthy female subjects aged 16 to 26 as compared with Gardasil^® 9 at one month after full-course vaccination with the experimental vaccines.

HPV 9-valent vaccines can prevent approximately 90% of cervical cancers and 90% of anal and genital warts, and is widely regarded as the most effective vaccine against HPV infections. At present, no domestic HPV 9-valent vaccine has been approved for sale in China. Completed Phase I clinical data of REC603 shows that it is safe and well tolerated with favorable immunogenicity profile. REC603 adopts H. polymorpha expression system to achieve high-yield and stable expression of HPV virus-like particles and to make the Company's vaccine candidate more suitable for commercial production. With well-defined critical process parameters and control strategies, manufacturing of REC603 can be easily scaled-up to meet the market demand domestically and globally.