RAPT Therapeutics has opened enrollment for prestIgE, a randomized, double-blind, placebo-controlled Phase 2b study of ozureprubart (formerly RPT904) in IgE‑mediated food allergy. The trial will evaluate two subcutaneous dosing schedules—every eight weeks and every 12 weeks with a loading dose—against placebo over 24 weeks, using a double-blind, placebo-controlled oral food challenge as the primary endpoint at Week 24. Approximately 100 participants with at least one allergy to peanut, milk, egg, walnut, or cashew will be enrolled across roughly 30 sites in the U.S., Canada, and Australia, with a 24‑week extension to Week 48 and safety follow-up thereafter.
The core development bet is straightforward: a half-life–extended anti‑IgE monoclonal antibody targeting the same epitope as omalizumab, with less frequent dosing. The company is advancing into food allergy on the heels of a positive Phase 2 readout in chronic spontaneous urticaria, another IgE-driven condition, and leveraging early preclinical and clinical work generated by a partner in China. The prestIgE design focuses on monotherapy, not combination with oral immunotherapy, and is built around DBPCFCs at Weeks 24 and 48 to anchor efficacy and durability.
Strategically, this is an attempt to carve out a “bio‑better” position in a class reshaped by omalizumab’s recent U.S. approval for food allergy. With omalizumab administered every two to four weeks and biosimilar competition approaching, RAPT’s differentiation hinges on matching class efficacy and safety while stretching dosing to eight or 12 weeks. That promise addresses clear operational pain points—visit frequency, chair time, staffing—and could support adherence in a chronic prophylactic setting. But the design’s placebo control means cross‑trial comparison to omalizumab benchmarks will be unavoidable, and payers will likely demand a clear convenience or cost‑offset narrative to justify a premium over branded or biosimilar options.
For research sites, the study’s reliance on DBPCFCs creates known logistical complexity: standardized challenge procedures, emergency readiness, and careful scheduling for multi‑allergen participants. Still, the lower visit burden associated with less frequent dosing may offset some throughput constraints if the regimen translates into practice. CROs and vendors with deep allergy operations and rigorous challenge standardization will be pivotal to minimizing variability across the multinational footprint. Regulators have increasingly favored functionally meaningful endpoints in food allergy; the prespecified challenge threshold and multi‑allergen inclusion criteria will signal how broad an eventual label could be and whether the effect generalizes across allergen types.
What comes next will depend on three elements: the magnitude of response against a clinically relevant challenge threshold at Week 24, the durability signal through Week 48, and an operational profile that supports either in‑clinic or potential at‑home administration over time. Safety around challenge procedures and any anaphylaxis signal will receive outsized scrutiny, given the class history and the real‑world context of accidental exposures. If ozureprubart delivers efficacy parity with materially longer dosing intervals, RAPT could move into Phase 3 with a credible convenience edge; absent that, the path narrows in a price‑pressured landscape where omalizumab’s incumbency and biosimilars compress margins. Watch for details on responder definitions, subgroup performance in multi‑allergen patients, pharmacodynamic consistency relative to baseline IgE, and early payer engagement to test whether reduced visit frequency can unlock a defensible value proposition.
Jon Napitupulu is Director of Media Relations at The Clinical Trial Vanguard. Jon, a computer data scientist, focuses on the latest clinical trial industry news and trends.
