Peanut oral immunotherapy increases desensitisation and remission in children

27th January 2022

Peanut oral immunotherapy in children has been shown in a randomised, placebo trial to increase rates of both desensitisation and remission

The use of peanut oral immunotherapy in children is associated with an increase in the proportion who achieve desensitisation and remission. This was the conclusion of a randomised, placebo-controlled trial by researchers from the Department of Paediatrics, Arkansas, USA.

Peanut allergy (PA) currently affects approximately 2% of the general population and commonly affects children as revealed in one study which how among 3218 children identified with food allergy, 24.8% reported a peanut allergy. Although allergy avoidance is the best strategy, in recent years, peanut oral immunotherapy has become more widely available and one product, Palforzia has been approved for use in the EU. Trial data shows that oral immunotherapy with Palforzia (known as AR101 in the study) in children and adolescents results in higher doses of peanut protein that could be ingested without dose-limiting symptoms and in lower symptom severity during peanut exposure at an exit food challenge compared to placebo. Nevertheless, whether use of oral immunotherapy can induce both desensitisation (i.e., a higher allergic reaction threshold) and remission, in other words, non-responsiveness after discontinuing therapy, is unclear.

For the present study, the US team undertook a randomised, placebo trial in children aged 12 years and younger and who were found to react to 500 mg or less or peanut protein, during a double-blind, placebo-controlled food challenge (DBPCFC). They randomised children 2:1 to peanut oral immunotherapy or placebo for a total of 134 weeks and which was equivalent to giving 2000 mg of peanut protein per day. This was followed by 26 weeks of no treatment and then re-assessment at week 160. The DBPCFC used a dose of 500 mg of peanut protein at week 134 and at week 160. At week 134, those who passed the DBPCFC challenge were considered to be desensitised and those who passed the challenge at week 160, deemed to be in remission. The primary endpoint was the proportion of children desensitised after 134 weeks of oral immunotherapy and the main secondary outcome was the proportion who were defined as in remission at week 160.

Findings

A total of 146 participants with a median age of 39.3 months (32% girls) were enrolled and 96 assigned to peanut oral immunotherapy.

At week 134, 71% of those receiving oral immunotherapy and 2% of those given placebo, met the primary outcome of desensitisation (risk difference, RD = 69%, 95% CI 59 – 79, p < 0.0001). The median tolerated peanut protein dose was 5005 mg (roughly 16 peanuts) for those given immunotherapy compared to 5 mg in the placebo group (p < 0.0001).

After discontinuation of immunotherapy, 21% of those previously receiving treatment and 2% of the placebo group, met the remission criteria (RD = 19%, 95% CI 10 – 28%, p = 0.0021) at week 160, although the tolerated dose of protein was lower at 755 mg for those who had immunotherapy but 0 mg for the placebo arm.

The authors concluded that peanut oral immunotherapy before age 4 increased both desensitisation and remission and called for future studies to focus on aged-defined benefits and risk to define the most appropriate window of opportunity to induce remission.

Citation

Jones SM et al. Efficacy and safety of oral immunotherapy in children aged 1 to 3 years with peanut allergy (the Immune Tolerance Network IMPACT trial): a randomised placebo-controlled study Lancet 2022

Efficacy of Palforzia in childhood peanut allergy increases over time

9th August 2021

Over a two-year period, daily use of Palforzia in those with a childhood peanut allergy led to higher level of allergen desensitisation.

An estimated approximately 2% of the population of Western nations has a peanut allergy. However, the prevalence in the paediatric population is likely to be higher with one study of 3218 finding that 24.8% had a childhood peanut allergy. The presence of a peanut allergy has the potential to cause life-threatening reactions and elicit anaphylaxis in both children and adults.

While the standard approach for those with a peanut allergy is allergen avoidance and the use of adrenaline auto-injection as a treatment for any allergic reactions following accidental ingestion, a peanut allergen powder, Palforzia, has been approved for use in the EU since 2020. Palforzia contains peanut protein as a defatted powder and has a marketing authorisation for the treatment of patients aged 4 to 17 years with a confirmed diagnosis of childhood peanut allergy.

Treatment with Palforzia is a form of oral immunotherapy that involves ingesting, small and controlled amounts of peanut protein with the aim of desensitising children and ultimately reducing the risk of life-threatening allergic reactions. However, continued treatment is required because once therapy is discontinued, reactivity to peanuts reoccurs.

The efficacy of Palforzia in childhood peanut allergy has been demonstrated in two Phase III randomised, controlled trials. In the first trial (PALISADE), 67% of participants who received Palforzia were able to ingest a dose of 600mg of peanut protein without any problems, compared to 4% of those assigned to placebo. In the second and more recent trial (ARTEMIS), 58% of those given Palforzia could tolerate 1000mg of peanut protein without problems compared with only 2% in the placebo group.

The same group have now reported follow-up data for patients who completed the PALISADE study in an open-label extension study. Individuals with childhood peanut allergy received 300mg/day for either 1.5 years (group A) or a total of 2 years (Group B). The primary outcome of the trial was a double-blind, placebo-controlled food challenge (DBPCFC), which involves supervised and gradual ingestion of the suspected food allergen (peanuts) disguised or hidden in another food.

Findings
The extension study included 142 participants aged 4–17 years (110 in Group A). The median age of group A was 10 years (52.7% male) whereas the median age of group B was 8 years (56.2% male). The percentage of participants able to tolerate the highest DBPCFC (2000mg peanut protein) and without any dose-limiting symptoms was 80.8% in group B compared with 48.1% in group A. In addition, the proportion of individuals requiring adrenaline as a rescue medication was 24% (group A) and only 3.8% (group B).

The researchers described how the data indicated that the extent of desensitisation to childhood peanut allergy was clearly time-dependent in how efficacy appeared to increase over time. They concluded that longer-term data will be captured from this ongoing study to determine whether continued therapy improves DBPCFC response.

Citation
Fernandez-Rivas M et al. Open-label follow-on study evaluating the efficacy, safety, and quality of life with extended daily oral immunotherapy in children with peanut allergy. Allergy 2021