RAPT Therapeutics and Shanghai Jemincare Pharmaceutical have entered into an exclusive licensing agreement for RPT904 (JYB1904), a novel, half-life extended anti-immunoglobulin E (IgE) monoclonal antibody. This agreement grants RAPT Therapeutics worldwide rights, excluding mainland China, Hong Kong, Macau, and Taiwan, to develop and commercialize RPT904. Jemincare will receive a $35 million upfront payment and is eligible for up to $672.5 million in milestone payments, plus royalties on future sales of RPT904 outside of the Jemincare Territory.
RPT904: A Potential Best-in-Class Anti-IgE Therapy
RPT904 is being developed as a potentially improved therapeutic option compared to omalizumab (Xolair), an anti-IgE monoclonal antibody already approved for various allergic disorders, including asthma, chronic spontaneous urticaria (CSU), chronic rhinosinusitis with nasal polyps, and food allergy. RAPT Therapeutics plans to initially focus on developing RPT904 for food allergy.
"We're delighted to partner with Jemincare and excited by RPT904 and its potential to be a novel best-in-class treatment option for patients with food allergy," said Brian Wong, M.D., Ph.D., President and CEO of RAPT. "Omalizumab's rapid uptake in food allergy since its approval earlier this year confirms the high unmet need and large opportunity in this growing market. RPT904 targets the same clinically validated epitope as omalizumab and combined with extended half-life, gives this molecule a best-in-class profile. We plan to initiate a Phase 2b clinical trial of RPT904 in food allergy in the second half of 2025."
Clinical Development and Ongoing Trials
Jemincare has completed a Phase 1 single-dose, dose-escalation study in 56 healthy volunteers in China, evaluating the safety, pharmacokinetics (PK), and pharmacodynamics (PD) of JYB1904. The study compared five dose levels of JYB1904 and one dose level of omalizumab to placebo. Results showed that JYB1904 had good safety and tolerability, with all treatment-related adverse events being Grade 1-2. The pharmacokinetics of JYB1904 were approximately dose-proportional, and the median half-life was more than two times that of omalizumab at the same dose. The Phase 1 study also demonstrated deeper and more sustained reduction of free IgE and higher total IgE accumulation by JYB1904 compared to omalizumab at the same dose.
Currently, Jemincare is conducting two Phase 2 trials of JYB1904 in China. One trial is focused on asthma, primarily assessing PK and PD profiles compared to omalizumab to inform dosing for a potential Phase 3 registrational trial, with topline data expected in the second half of 2025. The other Phase 2 trial is evaluating the safety and efficacy of JYB1904 in CSU, with topline data anticipated in the first half of 2026.
About RPT904
JYB1904/RPT904 is designed to bind free human immunoglobulin E (IgE), a key driver of allergic diseases. Early clinical studies have shown that RPT904 has more than twice the half-life and extended pharmacokinetic and pharmacodynamic properties compared to omalizumab, potentially offering a more effective treatment for food allergies, chronic spontaneous urticaria, and other allergic inflammatory diseases.
