Kymera Therapeutics presented positive Phase 1 results for KT-621, its first-in-class oral STAT6 degrader, in healthy Japanese adults at the Japanese Dermatological Association (JDA) Annual Meeting held June 11-14, 2026, in Kyoto, Japan. The data demonstrated a favorable safety profile and pharmacokinetic/pharmacodynamic (PK/PD) results consistent with previously reported KT-621 clinical studies. These findings support the global advancement of KT-621 for chronic Type 2 inflammatory diseases, including atopic dermatitis and asthma.

The randomized, double-blind, placebo-controlled Phase 1 study enrolled 24 healthy Japanese adults across two dose levels. Participants were randomized 3:1 to receive KT-621 or placebo once daily for seven days. The trial was designed to provide the PK/PD and safety data required by regulators prior to enrolling patients in Japan for global KT-621 Phase 2b studies.

KT-621 demonstrated rapid absorption and dose-proportional increases in plasma exposure. The drug achieved rapid, sustained STAT6 degradation in blood, with median degradation of at least 98% at both dose levels by Day 7. The treatment was well tolerated with a favorable safety profile, matching results seen in non-Japanese adults and atopic dermatitis patients. The company has previously reported positive Phase 1 data for KT-621 in non-Japanese healthy volunteers and patients with moderate to severe atopic dermatitis, showing robust reductions in disease-relevant Type 2 inflammatory biomarkers.

Jared Gollob, MD, Chief Medical Officer of Kymera Therapeutics, stated that the consistency across KT-621 Phase 1 studies reflects the strong translation of this approach from preclinical to clinical settings. He emphasized the potential of KT-621 to transform care for patients with chronic Type 2 inflammatory conditions through a novel oral treatment option.

Parallel Phase 2b trials for KT-621 are currently underway. The BROADEN2 trial focuses on atopic dermatitis, while the BREADTH trial targets asthma. Data from these studies are expected by mid-2027 and late 2027, respectively. These trials aim to accelerate development for subsequent parallel Phase 3 registration studies across multiple Type 2 inflammatory diseases.

The oral presentation at JDA was titled "KT-621, an Oral, Once Daily STAT6 Degrader: PK, PD and Safety in Healthy Japanese Adults." Sagar Agarwal, PhD, Vice President of Clinical Pharmacology at Kymera Therapeutics, delivered the presentation on June 12, 2026.

Kymera Therapeutics, Inc. has dosed the first participant in a first-in-human Phase 1 clinical trial evaluating KT-485 (SAR447971), an oral IRAK4 degrader, triggering a $20 million milestone payment from its partner Sanofi. The trial is assessing the therapy in adult healthy volunteers and patients with hidradenitis suppurativa (HS). This advancement marks a significant step in the collaboration between the two companies to develop novel oral treatments for immuno-inflammatory diseases.

Sanofi is leading the development, regulatory, and commercial efforts for the KT-485 program. Under the collaboration agreement, Kymera is eligible to receive up to $975 million in potential clinical, regulatory, and commercial milestones. The company retains an option to participate in future development and commercialization in the United States, with a 50/50 profit split, and is entitled to double-digit tiered royalties in the rest of the world (ROW).

Trial Details and Design

The Phase 1 trial (NCT07629336) is designed to evaluate the safety, tolerability, pharmacokinetics, and additional exploratory endpoints of orally administered KT-485. The study consists of three parts:

• Double-blind, placebo-controlled single ascending dose (SAD) cohorts
• Double-blind, placebo-controlled multiple ascending dose (MAD) cohorts
• An open-label MAD cohort

About KT-485

KT-485 is a second-generation oral degrader of IRAK4, a scaffolding kinase and key protein of the myddosome complex that mediates signaling through IL-1 and toll-like receptors. By eliminating IRAK4 completely through degradation, the therapy aims to impact both kinase and scaffolding functions. Preclinical testing demonstrated increased potency and specificity with a favorable safety profile.

"Advancing KT-485, our second generation IRAK4 degrader, into the clinic is an important milestone for our collaboration with Sanofi and our efforts to ultimately bring this important oral therapy to patients," said Nello Mainolfi, PhD, Founder, President and CEO of Kymera Therapeutics.