Abatacept to induce remission of peanut allergy during oral immunotherapy (ATARI): protocol for a phase 2a randomized controlled trial

Context

While oral immunotherapy (OIT) has been shown to promote the remission of mild peanut allergy in young children, there is still an unmet need for a disease-modifying intervention for older patients and those with severe diseases. In mice models, abatacept, a cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) immunoglobulin fusion protein, has been shown to promote immune tolerance to food when used as an adjuvant to allergen immunotherapy. The goal of this study is to explore the potential efficacy of abatacept in promoting immune tolerance to food allergens during OIT in humans.

Methods

In this phase 2a proof-of-concept study (NCT04872218), 14 peanut-allergic participants aged from 14 to 55 years will be randomized at a 1:1 ratio to abatacept vs. placebo for the first 24 weeks of a peanut OIT treatment (target maintenance dose of 300 mg peanut protein). The primary outcome will be the suppression of the OIT-induced surge in peanut-specific IgE/total IgE at 24 weeks, relative to the baseline. Sustained unresponsiveness will be assessed as a secondary outcome starting at 36 weeks by observing incremental periods of peanut avoidance followed by oral food challenges.

Discussion

This is the first study assessing the use of abatacept as an adjuvant to allergen immunotherapy in humans. As observed in preclinical studies, the ability of abatacept to modulate the peanut-specific immune response during OIT will serve as a proxy outcome for the development of clinical tolerance, given the small sample size. The study will also test a new patient-oriented approach to sustained tolerance testing in randomized controlled trials.

The Effect of Stimulus Duration on the Nostril Localization of Eucalyptol

The trigeminal system is a chemosensory system participating in the perception of most odorants, which allows for the perception of diverse sensations including the freshness of eucalyptus or the spiciness of pepper. The lateralization task, that is, the identification of the stimulated nostril in a monorhinal stimulation paradigm is only possible following trigeminal stimulation and allows therefore for the assessment of the trigeminal sensitivity also in a clinical setting. In this study, we aimed to determine the effects of the duration of stimuli on the lateralization task. To this end, we asked 32 young and healthy subjects perform the lateralization task while being exposed to eucalyptol stimuli ranging between 100 and 1250 ms. We found that participants performed on average at chance for stimuli shorter than 500 ms, and observed increasing accuracy for stimuli with longer durations. In conclusion, these data suggest that 500 ms represents a threshold for the lateralization of eucalyptol stimuli. Therefore, when trigeminal sensitivity is tested in a clinical setting, eucalyptol stimuli should have a duration of at least 500 ms.