Kymera Therapeutics Presents New Preclinical Data for KT-579, a First-in-Class, Oral IRF5 Degrader, at the American College of Rheumatology Annual Meeting

KT-579, a potent, selective, oral degrader of IRF5, demonstrated broad activity across multiple preclinical models of lupus and rheumatoid arthritis (RA), with activity comparable or superior to approved and clinically active therapies

KT-579 Phase 1 testing expected to begin in early 2026

WATERTOWN, Mass., Oct. 27, 2025 (GLOBE NEWSWIRE) --   (NASDAQ: KYMR), a clinical-stage biopharmaceutical company advancing a new class of oral small molecule degrader medicines for immunological diseases, today announced the presentation of new preclinical data for KT-579, its potent, selective, oral IRF5 degrader, demonstrating disease-modifying activity across multiple immuno-inflammatory diseases. The findings show that by selectively targeting and degrading IRF5, a master regulator of immune responses, KT-579 offers a novel oral approach to suppress multiple pro-inflammatory pathways implicated in diseases such as lupus and rheumatoid arthritis (RA). These data were presented at the American College of Rheumatology (ACR) Convergence Annual Meeting being held October 24-29, 2025, in Chicago, IL.

“KT-579’s compelling and consistent preclinical data demonstrating reductions in autoimmune symptoms and disease underscores the transformative potential of targeted protein degradation to address the pathogenic functions of IRF5 in specific disease contexts,” said Nello Mainolfi, PhD, Founder, President and CEO, Kymera Therapeutics. “By modulating this historically undrugged driver of multiple inflammatory cascades, we believe KT-579 could represent a transformative oral treatment for patients with complex rheumatic and autoimmune diseases, such as lupus and RA, who remain underserved by existing therapies.”

The Company previously shared data demonstrating KT-579’s encouraging profile in preclinical studies using human primary cell systems, patient-derived cells, and in vivo disease models, showing activity comparable or superior to existing standards of care. The new data presented at ACR further highlight KT-579’s robust activity across preclinical efficacy models of lupus and RA. In spontaneous lupus mouse models, KT-579 significantly impacted Type I IFN signaling and pathogenic B cell subsets, key molecular pathways known to be involved in lupus pathogenesis, that resulted in marked reductions of blood interferon-stimulated genes, serum autoantibodies (anti-dsDNA), kidney IgG deposition, and protected from renal disease progression. In RA rodent models, KT-579 achieved a dose-dependent reduction of joint swelling that correlated with inhibition of pro-inflammatory cytokines and Th1 responses in joint tissue and protected from bone destruction. Consistent with these in vivo mechanistic results, in vitro human co-culture experiments demonstrated that KT-579 can block Th1-skewing cytokines in monocytes, preventing pathogenic T cell differentiation and further validating its potential to rebalance immune responses.

Collectively, these findings reinforce KT-579’s multifaceted mechanism and its potential as a transformative oral therapy for rheumatic and autoimmune diseases driven by IRF5 dysregulation, such as lupus, RA, Sjögren’s, inflammatory bowel disease (IBD), among others. The Company intends to initiate Phase 1 testing for KT-579 in early 2026.

American College of Rheumatology (ACR) Convergence Annual Meeting

Title: Potent and Selective Oral IRF5 Degrader, KT-579, Demonstrates In Vitro and In Vivo Activity Comparable or Superior to Approved or Clinically Active Agents in Human Cellular Assays and Lupus Efficacy Models

Type/Session: Poster, B Cell Biology & Targets in Autoimmune & Inflammatory Disease

Speaker: Veroncia Campbell, Senior Director, Immunology

Date/Time: Monday, October 27, 2025, at 10:30AM -12:30PM CT

Title: Potent and Selective Oral IRF5 Degrader, KT-579, Blocks Pro-Inflammatory Cytokines and Reduces Joint Swelling in Rodent Models of Rheumatoid Arthritis

Type/Session: Poster, Innate Immunity

Speaker: Ryan Camire, PhD, Scientist, Immunology

Date/Time: Monday, October 27, 2025, at 10:30AM -12:30PM CT

Copies of the ACR presentations are available in the section of Kymera's website.

About Kymera Therapeutics

Kymera is a clinical-stage biotechnology company pioneering the field of targeted protein degradation (TPD) to develop medicines that address critical health problems and have the potential to dramatically improve patients’ lives. Kymera is deploying TPD to address disease targets and pathways inaccessible with conventional therapeutics. Having advanced the first degrader into the clinic for immunological diseases, Kymera is focused on building an industry-leading pipeline of oral small molecule degraders to provide a new generation of convenient, highly effective therapies for patients with these conditions. Founded in 2016, Kymera has been recognized as one of Boston’s top workplaces for the past several years. For more information about our science, pipeline and people, please visit or follow us on or .

Cautionary Note Regarding Forward-Looking Statements

This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995, as amended, including, without limitation, implied and express statements about our expectations regarding strategy, business plans and objectives on the development of our clinical and preclinical pipeline, including the therapeutic potential, clinical benefits and safety thereof, and the advancement of KT-579 into Phase 1 clinical testing in early 2026. The words "may," "might," "will," "could," "would," "should," "expect," "plan," "anticipate," "intend," "believe," "expect," "estimate," "seek," "predict," "future," "project," "potential," "continue," "target," “upcoming” and similar words or expressions are intended to identify forward-looking statements, although not all forward-looking statements contain these identifying words. Any forward-looking statements in this press release are based on management's current expectations and beliefs and are subject to a number of risks, uncertainties and important factors that may cause actual events or results to differ materially from any forward-looking statements contained in this press release, including, without limitation, risks associated with: uncertainties inherent in the initiation, timing and design of future clinical trials, the availability and timing of data from ongoing and future trials and the results of such trials, whether preclinical results will be indicative of the results of clinical trials, the ability to successfully demonstrate the safety and efficacy of drug candidates, the timing and outcome of planned interactions with regulatory authorities, the availability of funding sufficient for our operating expenses and capital expenditure requirements and other factors. These risks and uncertainties are described in greater detail in the section entitled "Risk Factors" in the most recent Quarterly Report on Form 10-Q and in subsequent filings with the SEC. In addition, any forward-looking statements represent our views only as of today and should not be relied upon as representing our views as of any subsequent date. We explicitly disclaim any obligation to update any forward-looking statements. No representations or warranties (expressed or implied) are made about the accuracy of any such forward-looking statements.

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