Frequently Asked Questions:
- What is KT-621?
KT-621 is an investigational, first-in-class, once-daily oral small molecule developed by Kymera Therapeutics. It degrades STAT6, a protein downstream of IL-4 and IL-13 signaling.
- What did the phase 1b trial of KT-621 show?
Among 22 adults with moderate to severe atopic dermatitis, 4 weeks of KT-621 reduced mean EASI by 62.6%. 76.2% of patients reached EASI-50, and the drug was well tolerated.
- Is KT-621 in later-stage trials?
Yes. The phase 2b BROADEN2 trial has completed enrollment, and topline results are expected by the end of 2026.
KT-621, an investigational oral STAT6 degrader, nearly eliminated STAT6 protein in blood and lesional skin and reduced disease severity by a mean of 62.6% after 4 weeks in adults with moderate to severe atopic dermatitis. The phase 1b results were presented at the 2026 Fall Clinical Dermatology Conference in Las Vegas, Nevada.¹ No treatment-related adverse events were reported.
Signal transducer and activator of transcription 6 (STAT6) sits downstream of both interleukin (IL)-4 and IL-13, the cytokines targeted by current injectable biologics for atopic dermatitis. KT-621, developed by Kymera Therapeutics, is a first-in-class, once-daily small molecule designed to degrade STAT6 rather than inhibit it.¹
The poster was presented by Jared Gollob, MD, of Kymera Therapeutics. His co-authors included investigators from Red River Research Partners, Clinical Science Institute, and Cahaba Dermatology & Skin Health Center.¹
How Was KT-621 Studied in Atopic Dermatitis?
The single-arm, open-label phase 1b trial enrolled adults with a Validated Investigator Global Assessment for Atopic Dermatitis (vIGA-AD) score of 3 or higher and an Eczema Area and Severity Index (EASI) score of at least 16.¹ Participants received KT-621 100 mg (n = 10) or 200 mg (n = 12) once daily for 28 days, followed by 14 days of follow-up.
The 22 treated patients had a mean baseline EASI score of 24.9, and 45.5% had severe disease (vIGA-AD of 4).¹ End points at week 4 included STAT6 degradation in blood and skin, Type 2 inflammatory biomarkers, clinical activity and safety.
How Deeply Did KT-621 Degrade STAT6?
Both doses produced comparable degradation, with median STAT6 reductions of 97.5% in blood and 93.6% in lesional skin.¹ Across doses, median reductions in blood biomarkers were 47.9% to 54.8% for thymus and activation-regulated chemokine (TARC), 62.0% to 72.9% for eotaxin-3 and 54.1% to 56.0% for IL-31. Immunoglobulin E declined more modestly, by 5.3% to 14.2%.
What Clinical Activity Did KT-621 Show at 4 Weeks?
Across doses, mean EASI improved by 62.6%; 76.2% of patients reached EASI-50, and 28.6% reached EASI-75.¹ vIGA-AD 0/1 was achieved by 19.0%, and mean affected body surface area fell by 49.0%.
