RAPT Therapeutics, a clinical-stage biopharmaceutical company, has announced initiation of its randomized, double-blind, placebo-controlled prestIgE Phase 2b clinical trial for ozureprubart (formerly RPT904). The trial is a critical step in developing a new therapeutic option for patients suffering from IgE-mediated food allergies, an inflammatory condition that impacts millions globally. The decision to advance into this Phase 2b study follows promising results the company observed in an earlier Phase 2 trial of the drug in chronic spontaneous urticaria, another IgE-driven disease, underscoring the potential of this differentiated anti-IgE therapy.
The trial’s launch marks a significant effort to address the substantial and rising global incidence of food allergies. Commenting on the milestone, Brian Wong, MD, PhD, President and CEO of RAPT, emphasized the urgency of the condition:
Food allergies are a large and growing problem for millions of patients worldwide… Initiating this trial is a significant milestone that reflects our strong execution, the validity of the early preclinical and clinical data generated by our partner, Jeyou, in China and our mission to provide patients with an improved anti-IgE therapy.
The company is actively collaborating with leading food allergists across the US, Canada, and Australia to advance the development of ozureprubart.
Ozureprubart is designed as a novel, half-life extended anti-IgE monoclonal antibody (mAb). Its development as a potential “bio-better” version of existing treatments is a key focus for RAPT. Hugh Sampson, MD, Director Emeritus of the Jaffe Food Allergy Institute, highlighted the drug’s potential, noting:
As a half-life extended anti-IgE monoclonal antibody, ozureprubart has the potential to be a transformative new therapeutic option for patients with food allergies. Targeting the same epitope as omalizumab, ozureprubart is a bio-better that is designed to match omalizumab’s established efficacy and safety profile while offering significantly improved durability and reduced dosing frequency.
The prestIgE Phase 2b trial is structured as a two-part, multi-center study. It aims to assess the efficacy and safety of ozureprubart monotherapy, utilizing approximately 30 clinical sites across the U.S., Canada, and Australia. Part 1 of the trial will enroll approximately 100 participants diagnosed with at least one food allergy, specifically to peanut, milk, egg, walnut, or cashew, to be treated for 24 weeks.
In the first part of the study, participants are randomized in a 2:2:1 ratio to compare two distinct subcutaneous dosing regimens of ozureprubart — either administered every 8 weeks or every 12 weeks, both including a loading dose — against a placebo. The primary endpoint is defined as the proportion of participants who successfully achieve a prespecified target threshold during a crucial scientific measure: the double-blind, placebo-controlled, oral food challenge (DBPCFC) conducted at the end of the initial 24-week treatment period.
Following the initial assessment, Part 2 of the trial will see participants in the ozureprubart arms continue their respective treatments for an additional 24 weeks. Meanwhile, participants who were initially on placebo will be re-randomized 1:1 to begin receiving ozureprubart every 8 weeks or every 12 weeks. All participants will undergo a second DBPCFC at the 48-week mark, followed by an additional 16-week safety follow-up period to fully monitor the drug’s long-term profile.
Ozureprubart’s function is to inhibit free and cell-bound Immunoglobulin E (IgE), the central antibody that drives allergic reactions. As a half-life extended anti-IgE mAb, it is designed to modulate the critical immune responses underlying these inflammatory diseases. By demonstrating extended pharmacokinetics and pharmacodynamic properties compared to first-generation anti-IgE therapies, ozureprubart is positioned as RAPT’s novel approach to providing a more durable and patient-friendly treatment option for a range of allergic inflammatory diseases, starting with this pivotal food allergy trial.
