RAPT Therapeutics (RAPT) Study Result summary

Study Overview and Design

• Phase II trial in China randomized 135–137 adults with chronic spontaneous urticaria (CSU) inadequately controlled by antihistamines to RPT904 (JYV1904) every 8 or 12 weeks or omalizumab every 4 weeks for 16 weeks.

• Randomized, double-blind, active-controlled design with balanced demographics and severe baseline UAS7 scores.

• Primary endpoint: change from baseline in UAS7 at weeks 8, 12, and 16; secondary endpoints included complete response (UAS7=0), itch and hive severity, angioedema, and quality of life.

• High completion rates and minimal discontinuations unrelated to adverse events were observed.

• Study conducted at multiple sites in China.

Efficacy and Safety Results

• Both RPT904 dosing arms showed rapid, durable, and numerically superior or comparable efficacy to omalizumab at all time points on UAS7 and complete response rates.

• At week 16, RPT904 Q8W and Q12W arms improved UAS7 by up to 23.2 and 22.2 points, respectively, versus 19.1 for omalizumab; complete response rates (UAS7=0) were up to 46% for RPT904 and 32% for omalizumab.

• Efficacy was sustained at week 16 after a single dose of RPT904 Q12W, indicating high durability.

• RPT904 showed strong results on secondary endpoints, including itch and hive severity scores.

• No treatment-related serious adverse events, anaphylaxis, or discontinuations due to adverse events were reported; safety profile was similar to omalizumab.

Mechanism, Competitive Landscape, and Future Plans

• RPT904 is a next-generation, half-life extended anti-IgE antibody with higher affinity, reduced immunogenicity, and improved dosing convenience compared to omalizumab.

• RPT904 blocks IgE binding, removes IgE from mast cells/basophils, and downregulates FcεRI, targeting the key driver of allergic reactions.

• Market research suggests less frequent dosing and higher efficacy could make RPT904 a preferred option for advanced CSU therapy.

• Plans include advancing RPT904 to Phase 3 in CSU, initiating Phase 2b in food allergy, and expanding to asthma, with regulatory discussions ongoing.

• Additional efficacy and safety data will be presented at future conferences; regulatory alignment and market access are key focuses.