The use of the basophil activation test in clinical trials
BAT has a huge potential in clinical trials, both as a biomarker of clinical response to treatment and in the exploration of possible underlying mechanisms at the effector cell level. However, there are practical aspects that need to be considered in order for the results to be informative, reproducible and comparable between sites. Table 1 presents some of the practical issues and recommendations to circumvent them and reach an optimal use of BAT in the context of clinical trials.
In addition to being a surrogate of clinical outcomes of therapies, a key application of BAT in future clinical trials is to confirm eligibility of patients for allergy treatment. This is particularly important in the context of food allergy, for which, at the moment eligibility for food IT requires the performance of allergen challenge in patients that have been previously diagnosed with food allergy. Having to undergo an oral food challenge for a patient known to be allergic can be quite stressful and additional challenges are often required in study protocols to assess clinical response to IT. This approach is unlikely to be well accepted by patients and families in clinical practice, as patients being considered for treatment have already been diagnosed with food allergy and may be fearful of exposure to the allergen, even in the context of an oral food challenge. Depending on the threshold of reactivity required, challenges done as part of study protocols can exclude allergic patients with high threshold of reactivity that would otherwise benefit from such treatment. Similar considerations can be made for biologicals, which are often reserved for patients with severe allergic conditions, that may be at additional risk of undesirable outcomes during allergen challenges.