Food allergy affects 1 in 30 children, and is the commonest trigger for life-threatening reactions (anaphylaxis) in this age group. It is a major public health issue, with practical implications for industry, education and healthcare systems. Oral immunotherapy (OIT) is an emerging treatment option, where small, increasing doses of a food allergen are used to cause "desensitisation", so food-allergic individuals no longer have symptoms when exposed to the trigger food. However, frequent allergic reactions during OIT (including anaphylaxis) are common, and can lead to patients having to stop treatment. In addition, food-allergic children usually dislike the taste of the food they are allergic too, which affects compliance and treatment success. There is a lack of longer-term data to inform cost-effectiveness analyses for OIT.

The NATASHA study will recruit young people from age 6+ years with IgE-mediated peanut allergy, and young people aged 3+ years with IgE-mediated allergy to cow's milk, who will undergo oral immunotherapy for these allergens using real-world foods (taken carefully according to a standardised protocol under medical supervision). In addition to assessing efficacy and safety outcomes, we will also collect longer-term data to evaluate cost-effectiveness in the UK setting.

Inclusion Criteria:

1. Age 6-23 years with IgE-mediated peanut allergy, or age 3-23 years with IgE-mediated food allergy to cow's milk
2. Past history consistent with IgE-mediated allergy to the relevant allergen
3. Allergic to cumulative ≤1.44 g protein (of the specific allergen) at baseline DBPCFC, prior to treatment allocation
4. Written informed consent (for young people under 16, consent from the parent/legal guardian (AND assent from the young person when the young person is age 6+ years)

Exclusion Criteria:

1. Required previous admission to an intensive care unit for management of an allergic reaction

2. Clinically significant chronic illness (other than asthma, rhinitis or eczema)

3. Moderate-severe eczema, defined as requiring more than once daily application of 1% hydrocortisone or equivalent topical calcineurin inhibitor as maintenance treatment despite appropriate use of emollients (eczema is not otherwise an exclusion criteria)

4. Poorly controlled asthma within the previous 3 months (as defined by clinician judgement with reference to the International Consensus On (ICON) Pediatric Asthma consensus), or asthma requiring treatment with >5 days oral corticosteroids within the previous 3 months

5. Previous history of eosinophilic oesophagitis

6. Undergoing subcutaneous or sublingual immunotherapy to respiratory allergens, and not yet established on maintenance dosing for at least 6 months

7. Undergoing allergen immunotherapy for food allergy and within the first year of treatment

8. In CM-allergic children under consideration for desensitisation to CM:

   • currently consuming CM-containing products other than extensively-heated milk in baked foods (e.g. biscuits, cakes)
   • significant symptoms of non-IgE-mediated CM allergy within the previous 12 months

9. Taking prebiotic or probiotic supplements and unwillingness to discontinue

10. Subjects receiving anti-IgE therapy, oral immunosuppressants, beta-blocker or Angiotensin Converting Enzyme (ACE) inhibitor

11. Tolerance to cumulative ≥1.44 g food protein at initial DBPCFC during screening

12. Objective allergic reaction to ≤4mg cow's milk protein or ½ Reese's puff in peanut-allergic children, during screening

13. Objective reaction to the placebo at screening DBPCFC

14. Past or current medical issue, participation in another clinical trial or other consideration, which, in the opinion of the investigator, may pose additional risks from study participation, interfere with compliance or otherwise impact on the quality or interpretation of study data

15. Pregnancy

16. Direct personal or commercial relationship with a member of the local study team directly involved with the conduct of the trial

17. Unwilling or unable to fulfil study requirements, including the requirement for appropriate supervision following dosing at home)

Deidentified data may be available upon request to the Chief Investigators, subject to local data protection legislation.

Outcomes assessed by double-blind, placebo-controlled food challenge