RAPT Therapeutics announced that the U.S. Food and Drug Administration has cleared the company's Investigational New Drug application to proceed with a Phase 2b clinical trial of RPT904 for treating patients with food allergies. The clearance represents a significant regulatory milestone for the clinical-stage immunology company's next-generation anti-IgE therapeutic candidate.
"Clearance of our IND application, which included data from our Chinese partner Jeyou, is an important and meaningful step for the program," said Brian Wong, M.D., Ph.D., President and CEO of RAPT Therapeutics. "We are excited to advance clinical development of RPT904, our next-generation, half-life extended anti-IgE molecule with a differentiated product profile."
Phase 2b Trial Design and Endpoints
The Phase 2b trial, designated "prestIgE," is designed as a two-part, multi-center, randomized, double-blind, placebo-controlled study to assess the efficacy and safety of RPT904 monotherapy in participants with IgE-mediated food allergies. The study will compare two dosing regimens of RPT904 administered subcutaneously every 8 weeks or every 12 weeks to placebo in a 2:2:1 ratio.
In Part 1, approximately 100 participants with at least one food allergy to peanut, milk, egg, walnut, or cashew will receive treatment for 24 weeks. Both RPT904 dosing arms will include a loading dose at Week 2. The primary endpoint is the proportion of participants who achieve a prespecified target threshold at a double-blind, placebo-controlled oral food challenge at Week 24.
Part 2 extends the treatment period for another 24 weeks, with participants in the RPT904 treatment arms continuing their assigned regimens while placebo participants are re-randomized 1:1 to receive RPT904 either every 8 weeks or every 12 weeks through Week 48. All participants will undergo a double-blind, placebo-controlled oral food challenge at Week 48, followed by an additional 16-week safety follow-up period.
RPT904 Mechanism and Differentiation
RPT904 is a novel, half-life extended anti-IgE bio-better monoclonal antibody that targets the same epitope as omalizumab for treating food allergies, chronic spontaneous urticaria, and other allergic inflammatory diseases. The therapeutic candidate is designed to inhibit both free and cell-bound human immunoglobulin E, a key driver of allergic diseases.
In early clinical studies, RPT904 has demonstrated extended pharmacokinetic and pharmacodynamic properties compared to omalizumab, the first-generation anti-IgE monoclonal antibody. This enhanced profile potentially allows for less frequent dosing while maintaining therapeutic efficacy.
Clinical Development Timeline and Partnership Data
RAPT Therapeutics is on track to initiate the Phase 2b clinical trial by the end of 2025, moving closer to delivering what the company describes as a best-in-class therapeutic option for the large and underserved food allergy community. The FDA clearance incorporated data from the company's Chinese partner Jeyou, which is conducting separate Phase 2 trials of RPT904 in chronic spontaneous urticaria and asthma.
Wong noted that the company expects data from Jeyou's Phase 2 trials in chronic spontaneous urticaria and asthma by the end of 2025, which could provide additional insights into RPT904's therapeutic potential across multiple allergic conditions.
Addressing Unmet Medical Need
The development of RPT904 targets a significant unmet medical need in the food allergy treatment landscape. RAPT Therapeutics characterizes the food allergy community as large and underserved, highlighting the potential clinical impact of a more convenient dosing regimen compared to existing anti-IgE therapies.
The company's focus on developing novel therapies designed to modulate critical immune responses underlying inflammatory and immunological diseases positions RPT904 as a potentially important addition to the treatment armamentarium for patients with food allergies and related allergic conditions.
