YS Biopharma Co., Ltd. (Nasdaq: YS) ("YS Biopharma" or the "Company"), a global biopharmaceutical company dedicated to discovering, developing, manufacturing, and delivering new generations of vaccines and therapeutic biologics for infectious diseases and cancer, today announced positive interim results from the ongoing Phase 3 clinical trial (the "Phase 3 Trial" or the "Trial") of its next-generation PIKA Rabies Vaccine. The interim results indicate that the PIKA Rabies Vaccine has successfully met the primary endpoints of the Trial and has the potential to achieve best-in-class accelerated protection and meet the WHO's goal of a one-week rabies vaccine regimen to replace the conventional three- or four-week regimens.

The PIKA Rabies Vaccine, which utilizes YS Biopharma's proprietary PIKA adjuvant technology, is designed to produce a more robust immune response in an accelerated timespan compared to existing rabies vaccines. It was granted orphan drug designation by the US FDA for prevention of rabies virus infection including post-exposure prophylaxis (PEP) for rabies.

The pivotal registration Phase 3 Trial is a randomized, comparator-controlled, double-blind, multicenter trial which includes 4,500 participants from the Philippines and Pakistan. It is designed to assess the immunogenicity, safety, and lot-to-lot consistency of three lots of the PIKA Rabies Vaccine in healthy adults using a 7-day vaccine schedule, versus a globally marketed comparator following the standard 28-day regimen. The primary immunogenicity endpoints of the study were geometric mean titers (GMTs) of rabies virus neutralizing antibodies (RVNA) and RVNA seroconversion rate at Day 14 in the first 900 participants. The secondary immunogenicity endpoints were RVNA seroconversion rate and GMTs of RVNA at Day 28, Day 42, Day 90, and Day 180 in the first 900 participants, and RVNA seroconversion rate at Day 7 and Day 365 in all participants.

Based on the interim data analysis, the PIKA Rabies Vaccine demonstrates non-inferior immunogenicity to a globally marketed comparator, while also helping patients achieve immunity in a shorter timeframe of 7 days. The data, which comes from the first 900 participants enrolled in the Trial, revealed that the RVNA seroconversion rate of the PIKA Rabies Vaccine was twice that of the comparator by Day 7, showing the superiority of PIKA rabies vaccine to offer quick onset of protection against virus infection. This accelerated and higher seroconversion rate came at no cost to safety, with the safety profile of the PIKA Rabies Vaccine remaining highly tolerable.

Dr. Zenaida Mojares, Chief Medical Officer of YS Biopharma, commented, "The interim results of the pivotal Phase 3 Trial provide compelling evidence of the robust immunogenicity and favorable safety profile of the PIKA Rabies Vaccine. By providing a shortened treatment regimen without sacrificing safety or quality, the PIKA Rabies Vaccine has the potential to improve rabies treatment and compliance. At present, the long and inconvenient regimen length for existing rabies vaccines represents a major barrier to treatment completion, and we are eager to see how the enhanced speed of the PIKA Rabies Vaccine might have a positive impact on patients. We are proud of our team for the hard work and dedication which got us to this point, and we are excited to see how our advances will contribute to the ongoing global fight against rabies."

Dr. David Shao, Director, President, and CEO of YS Biopharma, added, "We would like to extend our sincere gratitude to all the investigators and participants who participated in the clinical trial. Thanks to their dedication and efforts, animal bite patients are expected to have access to a new rabies vaccine, thereby reducing the rate of immune failure. We remain committed to working closely with drug regulatory agencies in various countries including the Philippines, Pakistan, Singapore, China, and other jurisdictions regarding the product registration and marketing application. We eagerly anticipate the early approval of this innovative therapy for the benefit of patients worldwide."