Aardvark Therapeutics lowered the minimum age of eligibility in its Phase 3 HERO trial of ARD-101 for hyperphagia in Prader–Willi syndrome (PWS) from 13 to 10, following alignment with FDA on a protocol amendment. No efficacy data accompanied the update, but the company guided to a topline readout in the third quarter of 2026.
The core move expands the addressable trial population in a rare disease where enrollment is chronically rate-limited and heterogeneity in symptom onset can complicate signal detection. Broadening to 10–12-year-olds leans into the field’s recurring premise that earlier intervention may yield more measurable reductions in hyperphagia and caregiver burden. It also fits within a regulatory context that is increasingly explicit about pediatric planning; ARD-101 already holds Orphan Drug and Rare Pediatric Disease designations in PWS, and a successful program could be voucher-eligible. Mechanistically, ARD-101 is a gut-restricted agonist of bitter taste receptors (TAS2Rs) that triggers enteroendocrine release of GLP-1 and CCK, positioning it as a non–CNS pathway in a space where prior approaches have struggled to balance efficacy with tolerability.
Strategically, the amendment looks like a pragmatic enrollment accelerator and a hedging maneuver on effect size. PWS trials often anchor on caregiver-reported hyperphagia measures that can plateau in older adolescents; enrolling younger patients may increase the dynamic range of change on standardized instruments while simultaneously increasing the recruitment funnel. Alignment with FDA suggests the agency is comfortable with the safety rationale for moving younger, likely informed by earlier-phase exposure and the compound’s gut-restricted profile. For Aardvark, the decision also shores up optionality ahead of a pivotal-like readout timeline, mitigating risk that a single age band underdelivers on the primary endpoint.
Operationally, sites and CROs will need to re-consent families, obtain new IRB/IEC approvals, and implement pediatric-specific procedures, including assent, growth and pubertal monitoring, and potentially weight-adjusted dosing or formulation considerations for smaller patients. Caregiver engagement becomes more central in this cohort; adherence to ePRO schedules and consistency of daily hunger reporting during school routines can materially affect data completeness. Sponsors will need to guard against signal dilution by ensuring age and baseline severity stratification, pre-specifying subgroup analyses, and considering sample-size re-estimation once the younger cohort accrues. The amendment’s timing also matters: introducing a new age stratum midstream can complicate statistical analysis and site workflow if operationalized unevenly across geographies.
The competitive backdrop remains active. PWS hyperphagia programs have seen mixed outcomes, with diazoxide choline advancing on renewed data and intranasal oxytocin analogs encountering uneven efficacy. GLP-1–based therapies now reach into adolescent populations but are not standard in PWS and have varying approvals by age, leaving a therapeutic gap below 12 that ARD-101 could help address if efficacy and safety are consistent. A gut-restricted, hormone-mediated approach may reduce CNS-related safety oversight and simplify site operations compared to centrally acting agents, though gastrointestinal adverse events and weight trajectory monitoring will still require disciplined management.
What to watch next is whether the revised HERO protocol discloses caps for the 10–12 cohort, adjustments to stratification factors, and any interim operating characteristics that preserve power across age bands. The near-term risk is operational: can sites activate the amendment without slowing randomization, and can caregiver-reported endpoints maintain reliability in younger participants? The longer-term question is regulatory: will FDA view a cross-age efficacy signal as sufficiently consistent for a single-label approach, or demand age-specific data cuts? If enrollment accelerates and the signal holds across strata, Aardvark positions itself for a cleaner path to filing under its pediatric designations; if not, the age expansion could complicate the analysis set and push the timeline beyond the projected Q3 2026 readout.
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.
