Apogee Therapeutics Acquisition

AbbVie announced a major acquisition on June 22 of Apogee Therapeutics for $10.9 billion.^[1] Apogee's clinical stage pipeline is centered around their lead asset Zumilokibart (APG777), a humanized IgG1 monoclonal antibody (mAb) IL-13 inhibitor.^[2] The therapy is advancing towards a phase 3 trial in atopic dermatitis in H2 of 2026, and is also being tested in combination with other molecules, including an OX40L inhibitor (APG990) for Atopic Dermatitis and a Thymic Stromal Lymphopoietin (TSLP) inhibitor (APG333) in COPD / Asthma.^[3] While far from leading the development pipeline, Apogee's TSLP inhibitor is a key component of the acquisition given TSLP's recognized significance. Not only does AbbVie single out Apogee's anti-TSLP monoclonal antibody as a key value proposition of the biotech's pipeline, but TLSP has become a prominent target in drug development due to its role as an upstream signaling cytokine heavily linked to atopic diseases (atopic dermatitis, asthma, allergic rhinitis and eosinophilic esophagitis).^[1][4] APG333 becomes AbbVie's first TSLP bet and gives them a shot at becoming a prominent player in the TSLP-based treatment landscape across atopic diseases.^[5]

While Apogee (now AbbVie) are a notable player in the TSLP landscape, there are several other drug developers further along in clinical trials with their anti-TSLP molecules, including AstraZeneca with their mAb Tezepelumab already on the market as the first FDA-approved TSLP inhibitor, on-label for Severe Asthma and more recently for additional indications.^[6][7] The list of approved TSLP-targeting therapies is slated to grow in the next few years, with multiple assets entering phase 3 clinical trials, and other notable assets across phases 1, 2 and preclinical stages.

TSLP Global Drug Development Landscape

Below is a global overview of TSLP-targeting therapies in the pipeline. Therapies spanning the discovery stage all the way through phase 3 trials are covered. In total, 31 assets are listed. Key features of the TSLP landscape include:

• Development spanning 5 indications - Astham, COPD, Atopic Dermatitis, CRSwNP, and Allergic Rhinitis (the most popular therapeutic target is Asthma)
• 26% of therapies in development by US companies, 55% by Chinese biotechs, 10% by European companies, and the rest through partnerships of biotechs across multiple regions (Strength of Chinese biotechs in the TSLP pipeline is considerable, eclipsing the US at this point in time.)

A few disclaimers to note about the dataset:

• While coverage is extensive, this landscape is not completely comprehensive of every TSLP therapy in development.
• The dataset is up to date as of April 1, 2026. Certain designations of phase, trial status, and even primary sponsor may have changed in the interim.
• Asset and trial details were largely gathered from global clinical trial registries, including ClinicalTrials.gov, the WHO ITCRP Registry, and the China Drug Trials Registry.^[8][9][10] Additional searches were conducted in International Conference Abstract Repositories, including ATS Pulmonology 2025, ERS 2025, EAACI 2025, and ACAAI 2025.^{[11][12][13][14]}

TSLP Global Pipeline