Kymera has begun dosing in BROADEN2, a 16-week, randomized, double-blind, placebo-controlled Phase 2b study of KT-621 in moderate to severe atopic dermatitis, enrolling about 200 patients across three dose levels. The primary endpoint is percent change from baseline in EASI at Week 16, with secondary endpoints including EASI-50/75, vIGA 0/1, and a ≥4-point improvement in Peak Pruritus NRS. Participants can roll into a 52-week open-label extension. An initial AD patient readout from a completed Phase 1b study is slated for December 2025, while BROADEN2 data are expected by mid-2027. A parallel Phase 2b asthma trial (BREADTH) is targeted to start in the first quarter of 2026.
The core move is a coordinated push to validate STAT6 degradation as a tractable, oral approach to Type 2 inflammation across dermatology and respiratory settings. KT-621 previously showed complete STAT6 degradation in blood and skin with low daily doses in healthy volunteers alongside reductions in Type 2 biomarkers and a safety profile comparable to placebo, setting the stage for patient-level efficacy tests. Kymera’s plan is to use the two Phase 2b programs to finalize dose selection and sequence into parallel Phase 3s across multiple Type 2 indications if the signal holds.
Strategically, this is an expansion play aimed at challenging injectable IL-4/IL-13 pathway biologics with oral convenience, while attempting to sidestep the safety baggage and labeling complexity facing JAK inhibitors in AD. Running AD and asthma in parallel mirrors how incumbents have built broad Type 2 franchises and could create efficiency in CMC, pharmacology, and safety database buildout. The tension is translational: degradation of a transcription factor must translate into tissue-level disease control with clinically competitive effect sizes and durability. The long arc to mid-2027 for AD Phase 2b data also stretches the timeline to registrational decisions and increases exposure to competitive moves from entrenched biologics expanding into adjacent Type 2 indications.
For sites and CROs, BROADEN2 is a conventional AD design, but the program’s biomarker orientation and prior use of skin sampling may add operational layers around biopsy logistics and central lab coordination. Pruritus NRS requires reliable ePRO capture; vendors with dermatology-specific UX and adherence tooling will be relevant. The asthma study launch in early 2026 will demand cross-specialty alignment and could help Kymera cultivate a multi-indication site network, though recruitment will compete with numerous AD and asthma trials from established players. The open-label extension may aid retention but adds drug supply and monitoring needs; if pediatric development follows, that will multiply site complexity.
What matters next is the December 2025 Phase 1b AD readout. Even directional improvements in EASI and itch, along with early onset and a benign safety profile, would de-risk dose selection and justify the parallel Phase 2b strategy. Conversely, a muted efficacy signal or safety surprises would force a rethink on pacing and indication breadth. Watch for biomarker–clinical response linkage, consistency across disease severities, and any steroid-sparing analyses. On the regulatory front, a clean safety trend and cross-indication coherence could support discussions on streamlined Phase 3 designs, but comparator choices against dupilumab-class agents and JAKs will shape both feasibility and labeling prospects. The broader question is whether an oral STAT6 degrader can replicate biologic-like outcomes without biologic-like monitoring; if it does, Kymera will have a pathway to a multi-indication Type 2 franchise, albeit on a timeline that requires disciplined execution and capital.
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.
