Early nonreactivity in the conjunctival provocation test predicts beneficial outcome of sublingual immunotherapy

Highlights and recent developments in airway diseases in EAACI journals (2018)

The European Academy of Allergy and Clinical Immunology (EAACI) supports three journals: Allergy, Pediatric Allergy and Immunology, and Clinical and Translational Allergy. EAACI's major goals include supporting the promotion of health, in which the prevention of allergy and asthma plays a critical role, and disseminating the knowledge of allergic disease to all stakeholders. In 2018, the remarkable progress in the identification of basic mechanisms of allergic and respiratory diseases as well as the translation of these findings into clinical practice were observed. Last year's highlights include publication of EAACI guidelines for allergen immunotherapy, many EAACI Position Papers covering important aspects for the specialty, better understanding of molecular and cellular mechanisms, identification of biomarkers for disease prediction and progress monitoring, novel prevention and intervention studies, elucidation of mechanisms of multimorbidities, introduction of new drugs to the clinics, recently completed phase three clinical studies, and publication of a large number of allergen immunotherapy studies and meta-analyses.

Strong dose response after immunotherapy with PQ grass using conjunctival provocation testing

Background

Pollinex Quattro Grass (PQ Grass) is an effective, well-tolerated, short pre-seasonal subcutaneous immunotherapy to treat seasonal allergic rhinoconjunctivitis (SAR) due to grass pollen. In this Phase II study, 4 cumulative doses of PQ Grass and placebo were evaluated to determine its optimal cumulative dose.

Methods

Patients with grass pollen-induced SAR were randomised to either a cumulative dose of PQ Grass (5100, 14400, 27600 and 35600 SU) or placebo, administered as 6 weekly subcutaneous injections over 31-41 days (EudraCT number 2017-000333-31). Standardized conjunctival provocation tests (CPT) using grass pollen allergen extract were performed at screening, baseline and post-treatment to determine the total symptom score (TSS) assessed approximately 4 weeks after dosing. Three models were pre-defined (Emax, logistic, and linear in log-dose model) to evaluate a dose response relationship.

Results

In total, 95.5% of the 447 randomized patients received all 6 injections. A highly statistically significant (p < 0.0001), monotonic dose response was observed for all three pre-specified models. All treatment groups showed a statistically significant decrease from baseline in TSS compared to placebo, with the largest decrease observed after 27600 SU (p < 0.0001). The full course of 6 injections was completed by 95.5% of patients. Treatment-emergent adverse events were similar across PQ Grass groups, and mostly mild and transient in nature.

Conclusions

PQ Grass demonstrated a strong curvilinear dose response in TSS following CPT without compromising its safety profile.

Conjunctival provocation tests: prediction of seasonal allergy

PURPOSE OF REVIEW

The conjunctival provocation test (CPT) is often used to clearly identify the specific allergen causing the symptoms of allergic rhinoconjunctivitis but also to assess the clinical efficacy of an allergen immunotherapy (AIT). As there is no consensus about its predictive value, the aim of this publication is to evaluate under which conditions the CPT can predict the symptom severity during the allergy season after previous AIT.

RECENT FINDINGS

Three out of four randomized controlled trials (RCTs) showed a correlation between CPT reactivity and symptoms occurring under natural allergen exposure after previous AIT. Furthermore, one RCT found that performing the CPT 4 weeks after initiating AIT can identify early responders who also show a benefit during the season. Another RCT suggested that conducting the CPT prior to starting AIT can be used to identify patients who may benefit more from treatment than others.

SUMMARY

The assessment of the reviewed literature led us to the conclusion that the CPT has a predictive value and can consequently be used to assess the efficacy of an administered AIT if performed according to a standardized challenge protocol with high-quality allergen extracts.