Efficacy and Safety of Intralymphatic Immunotherapy With Grass Allergoid and Microcrystalline Tyrosine: A...

Intralymphatic immunotherapy (ILIT) has been investigated for two decades in small clinical trials, typically using native allergens adsorbed to aluminium hydroxide (alum). This randomised, double-blind, placebo-controlled study evaluated the safety and efficacy of ILIT with a grass pollen allergoid formulated with microcrystalline tyrosine (MCT).

Sixty adults with grass pollen-induced allergic rhinoconjunctivitis (ARC) were randomised to receive ILIT with grass allergoid (equivalent to 60 ng Phl p 5; n = 31) or placebo (n = 29). Three ultrasound-guided injections (100 μL) were administered into inguinal lymph nodes at 4-week intervals in early 2022. The primary endpoint was the combined symptom and medication score (cSMS), recorded daily during the 2022 and 2023 grass pollen seasons. Secondary endpoints included safety, Rhinitis Quality of Life Questionnaire (RQLQ), serology, spirometry, fractional exhaled nitric oxide (FeNO), and skin-prick testing (SPT). An open-label extension, in which the placebo participants received active ILIT, was conducted in 2024.

ILIT was well tolerated, with no severe adverse events (SAEs). Mild local reactions (wheal, erythema, swelling) occurred after 50 of 93 active injections (53.8%), and three moderate reactions (3.2%) were reported. In the placebo group, one mild and no moderate reactions occurred. No allergen-specific systemic reactions were observed. Compared with placebo, ILIT reduced cSMS by 33% in 2022 (p > 0.05) and 50% in 2023 (p < 0.05). RQLQ improved with relative reductions of 22% and 13% (p > 0.05), respectively.

ILIT with a grass pollen allergoid formulated with MCT was well tolerated and associated with clinically relevant reductions in symptom and medication use in grass pollen-induced ARC. In this small study cohort, ILIT proved to be efficient and safe, but further optimisation of dosing regimens should follow.