The LMNOP trial will be a 2-armed, open-label, randomised controlled trial (RCT), 2:1. Over a period of 18 months, children in the Multi-Nut Oral Immunotherapy Treatment (OIT) Group (experimental arm) will undergo low dose OIT to two nuts they are allergic to. At this time, children in the Standard Care Group (control arm) will be instructed to strictly avoid consuming two nuts they are allergic to. Avoiding consuming nut allergens is the standard care advice for children with peanut/tree nut allergies in Australia. The trial will assess the difference in the proportion of participants undergoing Multi-Nut OIT who can achieve sustained unresponsiveness (SU) compared to the proportion of participants avoiding nuts who develop natural tolerance (NT), i.e. grow out of their allergy. SU is when a participant can pass an oral food challenge (OFC) after having paused OIT treatment for several weeks. Participants will be between the ages of 18 and 36 months at the time of screening. The first 12 participants enrolled will be part of the pilot phase, with a total of n = 45 for the main trial.

It is hypothesised that there will be a higher proportion of participants in the Multi-Nut OIT Group versus the Standard Care Group who pass the OFC following the 18-month treatment phase. That is, a higher proportion of participants in the Multi-Nut OIT Group will achieve SU compared to participants in the Standard Care Group achieving NT.

The LMNOP trial is a novel RCT assessing whether, over a period of 18 months, children undergoing low dose, multi-nut OIT can safely achieve SU at a higher rate than children under standard care who develop NT to peanut and tree nuts.

Trial Time Line

Study Entry - Children will undergo a screening skin prick test (SPT) to two of peanut, cashew, almond, hazelnut and/or walnut and OFC.

Children who meet the study eligibility criteria will be randomisation to either the Multi-Nut OIT Group or Standard Care Group for 18 months.

Multi-Nut OIT Group:

The 18-month treatment phase involves an escalation visit, build-up phase and maintenance phase. In the escalation visit, participants will receive 5 increasing doses of personalised multi-nut OIT in clinic at 20-minute intervals: 1 mg, 3 mg, 6 mg, 12 mg, 24 mg total nut protein, 12 mg/nut. The build-up phase will consist of daily home doses of multi-nut OIT and clinic visits every 2 weeks for up-dosing, up to a maintenance dose of 600 mg total protein, 300 mg/nut, over 3-8 months. In the maintenance phase, participants will continue to take their multi-nut OIT dose of 600 mg total protein each day at home for the remainder of the 18 months, with visits to the clinic every 3 months. 300 mg per allergen was chosen as the daily maintenance dose, as this is the lowest dose thus far demonstrated in any trial to successfully achieve SU.

Each dose will be mixed into a carrier food of the participant's choice (e.g. apple puree, custard, chocolate pudding etc).

At the end of the 18-month treatment phase, participants will have a SPT and OFC to their study nuts.

Participants who pass the OFC will cease OIT for 4 weeks. They will then undergo another OFC, 19 months after commencing treatment. Participants who pass this OFC will then enter the Ad libitum phase for 12 months. The Ad libitum phase involves participants eating the study nuts as much or as often as they want. To ensure the participant is consuming some nuts, they will be given advice that at a minimum, participants should have approximately ½ -1 teaspoon of nut flour, twice per week, for each nut.

At the end of the Ad libitum phase, participants will undergo another OFC.

Standard Care Group:

At the end of the 18-month period, participants will have a SPT and OFC to their study nuts.

Participants who pass their OFC will enter Ad libitum Phase for 12 months. As described for the Multi-Nut OIT Group, this involves participants eating the study nuts as much or as often as they want, with advice given that participants should have approximately ½ -1 teaspoon of nut flour, twice per week for each nut at a minimum.

At the end of the Ad libitum phase, participants will undergo another OFC.

Any Multi-Nut OIT Group participants who fail their OFC to one or both of their study nuts after the 18-month treatment phase will be asked to cease OIT to that nut(s) and will be referred back to their regular allergist. Likewise, any Multi-Nut OIT Group participants who fail their OFC to one or both of their study nuts after the 4 weeks of ceasing OIT will be asked to avoid the nut/s and will be referred back to their regular allergist. Any Standard Care Group participants who fail their OFC at this time, will be asked to continue avoiding that nut(s) and will also be referred back to their regular allergist. Participants in both groups who fail their OFC to both study nuts will be invited back at the end of the trial for a clinical assessment, but no OFC.

Primary Aim of the Pilot Phase:

To determine the feasibility of this study design in terms of recruitment into the study and completion of the escalation and build-up phases for participants in the Multi-Nut OIT Group.

Primary Aim of the Main Trial:

To compare the proportion of participants in the Multi-Nut OIT Group versus the Standard Care Group who pass the OFC after the 18-month treatment phase. That is, comparing the proportion of participants in the Multi-Nut OIT Group who achieve SU by passing their OFC after 18 months of OIT, and then passing another OFC after 4 weeks of ceasing OIT, to participants in the Standard Care Group who achieve NT by passing their OFC after the 18-month period.

Healthy children aged 18-36 months at the screening visit with confirmed/suspected Immunoglobulin E-mediated (IgE-mediated) allergies to 2 of: peanut, cashew, almond, hazelnut and/or walnut, and who meet the study criteria, will be recruited into the trial. Children will be randomised (2:1) for the pilot phase to either: multi-nut OIT (n ~ 8) or standard care (n ~ 4), and for the main trial - multi-nut OIT (n ~ 30) or standard care (n ~ 15). The 12 pilot participants will be included in the over all total of 45 participants.

Data from the first 12 participants enrolled, denoted the Pilot Phase, will be used to assess the feasibility of our study design in terms of the screening, recruitment, randomisation and treatment of participants, and examine the acceptability of low dose, multi-nut OIT in young children. Once the first 12 participants have been enrolled, we will pause recruitment until all Pilot Phase participants in the Multi-Nut OIT Group have completed the build-up phase (~ 8 months). At this point we will undertake an interim analysis of the feasibility data, and review whether any adjustments need to be made to the protocol. Following this, and assuming that there are no major issues with the study protocol and further funding has been secured, we will continue recruitment into the trial as per the protocol.

Potential participants will be identified from these sources: public and private Allergy clinics, Centre for Food & Allergy Research (CFAR) and Allergy & Anaphylaxis Australia (A&AA) websites and social media. For the Pilot Phase, recruitment will begin with distribution of the 'LMNOP Study Invitation' flyer electronically via the CFAR website and email list (270+ families interested in participating in food allergy research), and on Facebook via the Murdoch Children's Research Institute (MCRI) and Melbourne Allergy Centre and Children's Specialists (MACCS) private allergy clinic. Parents who have expressed interest in the study will be contacted, and those children deemed likely to be eligible for the study according to study criteria following a screening phone call, will be invited to attend a 2-day screening assessment at the Melbourne Children's Trials Centre (MCTC), MCRI.

Screening day 1: Following informed parental consent, children will have a SPT and blood will be drawn. Children with a positive SPT (≥3mm) to 2 of peanut, cashew, almond, hazelnut or walnut will be offered 2 individual nut OFCs to confirm allergy and reaction thresholds prior to randomisation. The OFC will not be needed if the child's allergy history meets the study criteria for a confirmed allergy. The first OFC will take place on Screening day 1.

Screening day 2: Children will have a 2nd individual nut OFC. This will be completed approximately one week after the first OFC.

Once the child has completed screening and has confirmed IgE-mediated allergy to 2 peanut/tree nuts (positive SPT (≥3mm), and OFC), they will enter the treatment phase, and will be randomised to either:

Multi-Nut OIT Group: Participants will undergo multi-nut OIT treatment using a personalised multi-nut flour - 2 of peanut, almond, cashew, hazelnut or walnut, 1:1 ratio of allergen protein. Multi-Nut OIT Group participants will continue strict avoidance of confirmed allergens outside of their daily dose of multi-nut flour, and will have 24-hour access to an on-call study doctor in case of allergic reactions.

Standard Care Group: As per standard clinical care in Australia, families will be instructed to strictly avoid all confirmed nut allergens over the 18-month period.

The Multi-Nut OIT Group will undergo an 18-month treatment phase consisting of an escalation visit, build-up phase and maintenance phase as described above. Participants who pass their OFC after 18 months of OIT, and then another OFC after no OIT for 4 weeks for one or both of their study nuts, will enter the Ad libitum phase described above. After 12 months of this unrestricted consumption of the study nuts, with a minimum of approximately 300 mg protein per nut: ½ -1 teaspoon of nut flour, twice per week for both nuts, participants will be assessed for induced tolerance (IT) via another OFC. IT is when a child can eat standard serves of the food 12 months after stopping OIT, without having an allergic reaction.

The Standard Care Group for the 18 months will be instructed to avoid any consumption of the peanut/tree nuts they are allergic to, as per standard care. Participants who pass the OFC for one or both of their study nuts at the end of the 18 months will undergo the 12-month Ad libitum phase. At the end of this 12-month period, participants will then be assessed for maintaining NT via an OFC. That is, whether they have still outgrown their allergy.

Inclusion Criteria:

• Is between the ages of 18 and 36 months at the time of Screening visit 1
• Has a legally acceptable representative capable of understanding the informed consent document and providing consent on the participant's behalf
• IgE-mediated allergy to 2 of peanut, almond, cashew, hazelnut or walnut, confirmed by:

Nut 1 pre-screening:

For at least one of almond, cashew, hazelnut or walnut (Nut 1)*:

1. History of ingestion with IgE-mediated reaction (birth to present) AND
2. History of SPT ≥3mm OR History of sIgE ≥0.35 number of kilounits per liter (KuL) AND

Nut 2 pre-screening:

For a second nut out of peanut, almond, cashew, hazelnut or walnut (Nut 2):

History of SPT ≥3mm OR History sIgE ≥0.35 KuL

In clinic screening: Participants meeting pre-screening criteria for Nuts 1 and 2 above will be invited for in-clinic screening

1. SPT: wheal size ≥3mm at Visit 1 for 2 of peanut, almond, cashew, hazelnut or walnut AND
2. OFC: react to ≤3000 mg protein top dose (4449 mg cumulative) in open, single nut OFC for 2 of peanut, almond, cashew, hazelnut or walnut

OFC not needed if:

History of failed OFC within past 3 months (confirmed by investigator review of discharge summary) OR History of anaphylaxis after ingestion within past 3 months based on investigator judgement +/- review of ER/Ambulance/medical notes

*Peanut is not included as Nut 1 to reduce the incidence of screening children with a peanut allergy only - children with peanut allergy may have been advised to avoid all other nuts. We require children to have eaten and reacted to at least one tree nut, and then the 2nd nut, which children may or may not have eaten, can be peanut or a tree nut.

Exclusion Criteria:

• History of severe anaphylaxis (as defined by persistent hypotension, collapse, loss of consciousness, persistent hypoxia or ever needing more than 2 doses of intramuscular adrenaline or an intravenous adrenaline infusion for management of an allergic reaction)
• Severe anaphylaxis at study screening OFC (defined as persistent hypotension, collapse, loss of consciousness, persistent hypoxia, or requiring more than 2 doses of intramuscular adrenaline or an intravenous adrenaline infusion for management of an allergic reaction)
• Fails either screening OFC on dose 1 (0.5 mg).
• Underlying medical conditions that increase the risks associated with anaphylaxis (e.g., cardiac disease or poorly controlled asthma (defined below))
• Confirmed eosinophilic esophagitis (EoE) or history indicating EoE
• Current use of beta-blockers or angiotensin-converting enzyme (ACE) inhibitors
• Receiving systemic immunomodulatory treatment
• Not commenced or unable to eat solid food
• Weight <7.5kgs (recommended minimum weight for EpiPen Jr (adrenaline autoinjector))
• Has a sibling in the study

Defining uncontrolled asthma (Global Initiative for Asthma. Asthma management and prevention for adults and children older than 5 years)

In the past 4 weeks, has the patient had:

Daytime symptoms more than twice/week? Any night waking due to asthma? Short Acting Beta Agonist (SABA) reliever needed more than twice/week? Any activity limitation due to asthma? Uncontrolled - answered yes to 3-4 of these

The de-identified data set that will be collected for this analysis of the LMNOP trial will be available six months after publication of the primary outcome. The study protocol may be obtained from the Murdoch Children's Research Institute. Prior to releasing any data, the following are required: a data access agreement must be signed between relevant parties; the LMNOP trial investigators must see and approve the analysis plan describing how the data will be analysed; there must be an agreement around appropriate acknowledgment; and any additional costs involved must be covered.

Should the study investigators be unavailable, this role is delegated to the Murdoch Children's Research Institute. Data will only be shared with a recognised research institute, which has approved the proposed analysis plan.

Six months after the publication of the primary outcome

Prior to releasing any data, the following are required: a data access agreement must be signed between relevant parties; the LMNOP trial investigators must see and approve the analysis plan describing how the data will be analysed; there must be an agreement around appropriate acknowledgment; and any additional costs involved must be covered.