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Anti-TSLP Bispecific Antibody GR2002 Shows Favorable Safety and Linear Pharmacokinetics in Phase 1 Trial
A single subcutaneous dose of GR2002 across five escalating doses (35–420 mg) was well tolerated in healthy Chinese adults, with adverse event rates comparable to placebo and no dose-dependent toxicity signal. The antibody demonstrated linear pharmacokinetics, a long half-life of up to 58.9 days, and dose-dependent suppression of serum TSLP at the higher doses tested.
What Was Studied
This trial evaluated GR2002, a novel bispecific antibody engineered to bind two distinct epitopes on thymic stromal lymphopoietin (TSLP), a cytokine implicated in driving type 2 inflammatory responses in conditions such as asthma, atopic dermatitis, and allergic rhinitis. The goal was to characterize the safety, tolerability, pharmacokinetics, pharmacodynamics, and immunogenicity of GR2002 in a healthy human population prior to advancing into disease-specific studies.
How It Was Studied
This was a randomized, double-blind, placebo-controlled, dose-escalation phase 1 trial conducted in healthy Chinese adults. Fifty participants were enrolled and divided into five sequential cohorts corresponding to single subcutaneous doses of 35, 70, 140, 280, or 420 mg. Within each cohort, participants were allocated in a 4:1 ratio to active drug (n = 40 total) or placebo (n = 10 total). All participants were followed for 85 days after dosing, with primary endpoints focused on safety and tolerability, and secondary endpoints covering pharmacokinetic profiling, pharmacodynamic target suppression, and anti-drug antibody formation.
What Was Observed
- Safety and tolerability were acceptable across all dose levels. A total of 92 treatment-emergent adverse events (TEAEs) were reported across both groups, with similar incidence between GR2002 and placebo recipients. Events were generally mild to moderate in severity, and no dose-dependent increase in adverse events was observed, suggesting the safety profile does not worsen with higher doses in this range.
- Upper respiratory tract infection was the most frequently reported treatment-related adverse event, occurring in 7 of 40 participants (17.5%) in the GR2002 group compared with 2 of 10 (20%) in the placebo group — a rate that was indistinguishable between arms and not attributable to the drug.
- GR2002 exhibited linear pharmacokinetics across the full dose range tested, with mean elimination half-life ranging from 26.0 to 58.9 days. Linear pharmacokinetics means that drug exposure increased proportionally with dose, a predictable behavior that simplifies dose selection for future trials.
- Dose-dependent suppression of serum TSLP from baseline was observed in the 140, 280, and 420 mg dose groups, providing pharmacodynamic evidence that GR2002 engages its target in vivo. Anti-drug antibodies were detected in 6 of 40 GR2002-treated participants (15%), indicating low but present immunogenicity that will require monitoring in longer-duration studies.
Why This Matters
TSLP blockade has emerged as a validated therapeutic strategy in inflammatory airway and skin diseases, with tezepelumab already approved for severe asthma. GR2002’s bispecific design — targeting two epitopes on TSLP rather than one — represents a mechanistically differentiated approach that may offer enhanced or more durable target neutralization. Demonstrating linear pharmacokinetics and target suppression in a first-in-human study provides a sound quantitative basis for dose selection in upcoming efficacy trials in patient populations.
How to Read This Result
These findings reflect a small, single-dose study in healthy individuals only, and neither efficacy data nor longer-term safety information in patients with TSLP-driven disease are yet available.
Limitations
The abstract does not explicitly report study limitations.