Persistent Benefit of Two-Year Artemisia annua Sublingual Immunotherapy for Seasonal Allergic Rhinoconjunctivitis

Artemisia pollen is a major aeroallergen source in Northern China that can cause multiple kinds of common allergic diseases. China's first Artemisia annua sublingual drops for Artemisia pollen-induced seasonal allergic rhinitis were launched in 2021. This study aimed to evaluate the efficacy and safety of a 2-year course of sublingual immunotherapy (SLIT) using A. annua allergen extract in patients with seasonal allergic rhinoconjunctivitis (SARC). Additionally, it sought to assess the sustained clinical efficacy of this therapy 1 year post-treatment.

Fifty patients (aged 4-60 years) with SARC and confirmed A. annua pollen allergy were enrolled in this study. In accordance with their preferences, the subjects were assigned to either the SLIT group (n = 25, receiving SLIT plus symptomatic treatment) or the control group (n = 25, receiving symptomatic treatment alone) at a ratio of 1:1. The entire study lasted for 3 years, initiating a 2-year treatment phase (2022 and 2023 pollen seasons) followed by a 1-year post-discontinuation follow-up period (2024 pollen season), with 2021 pollen season regarded as baseline. The total rhinoconjunctivitis symptom score (TRSS), total medication score (TMS), combined score of medication and rhinoconjunctivitis symptoms (CSMRS), and visual analogue scale (VAS) were compared between the two groups for clinical efficacy. In addition, the rhinoconjunctivitis quality of life questionnaire (RQLQ) was used to assess the impact of the A. annua SLIT on the quality of life of patients. Safety was evaluated based on adverse events.

A total of 41 patients completed the study (SLIT: n = 21, control: n = 20). There were no significant differences between the two groups during 2021 pollen season (baseline). However, the scores of TRSS (all p < 0.001), CSMRS (all p < 0.001), VAS (2022: p < 0.01; 2023: p < 0.001; 2024: p < 0.001), and RQLQ scores (2022: p < 0.01; 2023: p < 0.001; 2024: p < 0.001) were significantly lower than the control group during the 2-year SLIT treatment period and 1-year follow-up period. For TMS scores, although no statistically significant differences were found in 2022 and 2023 pollen seasons (p > 0.05), the SLIT group showed a decreasing trend. And TMS of SLIT group was significantly lower than that of the control group during 2024 pollen season (p < 0.05). In addition, RQLQ scores correlated positively with CSMRS and VAS (all p < 0.001).

A 2-year course of SLIT with A. annua allergen extract significantly alleviated symptoms and reduced medication use in SARC patients, with clinical benefits persisting for at least 1-year post-treatment phase.