The goal of this open-label, single escalating dose study in 3 sequential groups: adults, adolescents, and children with peanut allergy is to assess the safety of MOON101. The main question it aims to answer is:

1. the incidence and frequency of all treatment emergent adverse events (TEAEs) from baseline through study exit.
2. to determine the highest tolerated dose for each participant, as defined by the highest MOON101 dose level administered which did not cause a dose-limiting symptom (DLS).

The study will compare MOON101 and placebo. All participants will receive both active MOON101 (peanut allergen) and placebo (no peanut allergen).

As U44-MNLT-01 is a first-in-human study (investigating the safety of MOON101), initial enrollment will consist of peanut allergic adult participants who will receive placebo and escalating doses of MOON101 followed by enrollment of peanut allergic adolescents (aged 12-17 years) and peanut allergic children (aged 4-11 years). Prior to enrollment of each additional group, a safety review will occur.

This study is designed as an open-label, single escalating dose study in 3 sequential groups: adults, adolescents, and children with peanut allergy. A total of approximately 40 participants will be enrolled. This will be an outpatient study and participants will have a screening visit, 5 treatment visits, a follow up phone call 24 hours following each dose, one in-clinic follow-up visit (7 ± 2 days following their last dose) and a follow-up phone call (14 ± 2 days following their last dose). Three groups will be enrolled sequentially. Group 1 will be adults (n=10), Group 2 will be adolescents (n=10) and Group 3 will be children (n=20). Each group will receive up to 5 escalating doses of the investigational product (IP) as tolerated, with matching placebo at each dose level.

The independent National Institutes of Allergy and Infectious Diseases (NIAID) Data and Safety Monitoring Board (DSMB) will meet periodically at specified times throughout the trial to review safety data and make recommendations regarding the start of Group 2 and Group 3.

An initial group (Group 1) of adults (ages 18-55 years) with peanut allergy will each receive up to 5 doses of placebo and up to 5 single escalating doses of the IP as tolerated. Participants will receive placebo and MOON101 coated with 1 μg, 10 µg, 25 µg, 50 µg and 100 µg of peanut extract (PE), as tolerated, every 7 days. Each participant will receive both a placebo dose and a MOON101 dose at each treatment visit. The placebo and MOON101 will each be applied to the volar aspect of the arm (right and left arm, respectively) for 3 minutes. Following review of Group 1 safety data by the DSMB, Group 2 (adolescents with peanut allergy, ages 12-17 years) will be enrolled and will conditionally receive the same dosing regimen as Group 1. Finally, Group 3 (children with peanut allergy, ages 4-11 years) will be enrolled and will conditionally receive the same dosing regimen following confirmation of safety in Group 2 by the DSMB. Modifications to the dosing regimen may occur as recommended by the DSMB.

Each participant will be in the study for approximately 73 days, including a screening visit, up to 5 dosing visits with a 24-hour follow-up phone call after each dosing visit, 1 in-clinic follow-up visit, and a follow-up phone call.

Inclusion Criteria:

1. Participant and/or parent/guardian must understand and provide written informed consent and assent.

2. Aged 4 to 55 years per applicable enrolling group below of any sex/race/ethnicity at informed consent and assent (if applicable) form signature:

   1. Group 1: Adults; ages 18-55 years
   2. Group 2: Adolescents; ages 12-17 years
   3. Group 3: Children; ages 4-11 years

3. A physician-confirmed medical history of peanut allergy within minutes to 2 hours of ingesting peanut.

4. A peanut SPT with mean wheal diameter as defined by age.

Exclusion Criteria:

1. Laboratory evidence of liver or renal disease.
2. Poorly controlled or severe asthma/wheezing
3. Previous use of any form of peanut allergen immunotherapy within the 6 months prior to Screening.
4. Previous use of any biologic therapies such as omalizumab, dupilumab, benralizumab, reslizumab, tezepelumab, or any other immunomodulatory or immunosuppressive therapy (not including corticosteroids) within the 6 months prior to Screening.
5. Current use of β-blockers (oral), angiotensin-converting enzyme (ACE) inhibitors, angiotensin-receptor blockers (ARBs), or calcium channel blockers.
6. Treatment with a burst of oral, intramuscular (IM), intra-articular (IA), or intravenous (IV) steroids of more than two days within 30 days of Screening.
7. Unable to temporarily discontinue antihistamines (5 half-lives of the antihistamine) prior to SPT.
8. Unable to discontinue topical steroids to the testing application site for 24 hours prior to testing.

Other inclusion/exclusion criteria apply.