Efficacy of Tree SLIT-tablet and Betula pendula pollen extract in adolescents (12‑17) with allergic rhinitis/rhinoconjunctivitis caused by birch pollen

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What is this study about?

The study focuses on adolescents aged 12‑17 who experience allergic rhinitis and allergic rhinoconjunctivitis caused by exposure to birch pollen. The investigational product is a sublingual tablet containing birch tree extract, referred to as the tree SLIT-tablet, which is placed under the tongue to help the immune system become less reactive to the pollen. A matching inactive tablet, known as placebo, is used for comparison.

The primary aim of this phase IV randomised double-blinded trial is to determine whether the tree SLIT-tablet reduces allergy symptoms after at least 16 weeks of daily use in the target age group. Participants will be assigned to receive either the active tablet or the placebo without knowing which one they receive, and they will attend regular study visits for safety checks and symptom assessments.

During the study, participants will spend short periods in a specially designed environmental exposure unit, a room where the amount of birch pollen can be precisely controlled, allowing researchers to record symptom scores while the participants are exposed. Safety will be monitored throughout the treatment period, and the study will conclude after the final follow‑up visit.

1 initial study visit and randomization

you arrive at the study site for the first visit. after confirming your eligibility, you sign the consent form and provide baseline information such as your medical history and current symptoms.

the study team records measurements of your nasal and eye symptoms, vital signs, and performs basic lung function tests.

based on a computer‑generated sequence, you are randomly assigned to receive either the Tree SLIT-tablet or a matching placebo tablet. you will not know which one you receive.

2 receive study medication and dosing instructions

you are given a bottle containing either the active tablet or the placebo. each tablet contains 12 Standardised Quality Units (SQU) of the active substance and is meant to be taken by placing it under the tongue (sublingual use).

you are instructed to take one tablet every day, preferably at the same time each day, and to keep the tablet under the tongue until it dissolves completely.

the same daily schedule applies to the placebo tablet, which contains no active ingredient.

3 start daily dosing period

you begin the daily dosing regimen immediately after the first visit. the tablets are taken at home and are not required to be taken in the presence of study staff.

the daily dosing continues for a minimum of 16 weeks. you keep a diary to note the day you take each tablet and any symptoms or side effects you experience.

4 environmental exposure unit (EEU) sessions

periodically, you attend scheduled sessions in a special room called an environmental exposure unit. during each session, birch pollen is released into the air at a concentration of 0.09 µg/m³ (micrograms per cubic meter). this exposure mimics natural pollen conditions.

each EEU session lasts four hours. you sit comfortably while the pollen is inhaled (breathing in) and you record your nasal and eye symptoms every hour.

the primary measurement is the total symptom score (TSS) recorded between hours 2 and 4 of the session. secondary measurements include the total nasal symptom score (TNSS) and total ocular symptom score (TOSS) for the same time period.

5 regular safety and follow‑up visits

approximately every four weeks, you return to the study site for a safety check. during these visits, study staff measure your vital signs (such as blood pressure and heart rate), repeat lung function tests, and ask about any adverse events (side effects).

any serious adverse events, such as severe allergic reactions, are recorded and evaluated immediately.

6 end‑of‑treatment visit

after you have completed at least 16 weeks of daily dosing, you attend a final visit. all remaining tablets are collected, and a final set of symptom scores, lung function tests, and safety assessments are performed.

the study team reviews the overall results from the EEU sessions and your diary, and documents any final adverse events that occurred during the trial.

Who Can Join the Study?

Parents or caregivers must sign a written informed consent form before any study procedures, and the participant must also give permission according to local rules.
You must be a boy or girl who is between 12 and 17 years old on the day you are assigned to a study group.
If you are a girl who could become pregnant, you must have a negative pregnancy test and agree to use birth control methods until the final study visit.
You need a doctor’s diagnosis of moderate to severe allergic rhinitis or allergic rhinoconjunctivitis caused by birch pollen (you may also have asthma). This diagnosis must be confirmed even though you have used medicines that relieve symptoms for at least two past birch pollen seasons.
Blood tests must show a positive result for specific immunoglobulin E (IgE) against the birch pollen protein called Bet v. This means the IgE level is at least Class 2 (≥0.7 kU/L) within the last year.
A skin test called a skin prick test (SPT) must show a reaction (a raised bump called a wheal) of at least 5 mm to Bet v within the past year.
Your allergy symptoms must reach a certain level: a total symptom score (TSS) of at least 7 out of 18 and a total nasal symptom score (TNSS) of at least 6 out of 12 during a birch pollen exposure session.
You must be willing and able to follow all study instructions and attend the required visits.

Who Cannot Join the Study?

Previous participation in this trial – you cannot join if you have already been randomised in this study.
Acute severe oral inflammation – severe swelling or sores in the mouth.
Nasal or throat conditions that could affect results – includes enlarged tonsils, noticeable nasal polyps (small growths inside the nose), or a history of sinus or nasal surgery.
Eosinophilic oesophagitis – a condition where a type of white blood cell (eosinophil) causes inflammation of the food pipe.
Serious whole‑body allergic reaction – such as anaphylaxis (a severe reaction that can affect breathing and blood pressure), widespread hives (urticaria), or severe facial swelling (angioedema) that the doctor thinks may be risky.
Important chronic disease, including cancer – any long‑lasting illness that the doctor believes could interfere with the study or your safety.
Active or poorly controlled autoimmune diseases or immune system problems – conditions where the body attacks itself or has a weakened immune system, or cancers that are currently relevant.
Immunosuppressive treatment – medicines that suppress the immune system (such as certain chemotherapy or immune‑modulating drugs) taken within 90 days before the screening visit.
Anti‑IgE medicines – drugs that block a specific antibody involved in allergies, taken within about 130 days before randomisation.
Investigational drug use – any experimental medication taken within about 30 days before screening.
Participation in another interventional clinical trial – you cannot be in another trial while this study is running.
Allergy to other sources – having noticeable allergy symptoms (seasonal or year‑round) from allergens other than birch‑related tree pollen during the test periods.
Allergy, hypersensitivity, or intolerance to the study medication – except for the active ingredient, you must not be allergic to any other treatment used in the trial.
Pregnancy or breastfeeding – you cannot join if you are pregnant or feeding a baby.
Business or personal relationship with trial staff or sponsor – having a direct relationship with people running the study excludes you.
Household member also enrolled – another person living in the same home (such as a sibling or spouse) must not be in the trial at the same time.
Inability to follow study procedures – if you cannot cooperate or complete the required tests and visits.
History of alcohol or drug abuse.
Asthma requiring medium or high daily doses of inhaled steroids – asthma that needs step 4 or 5 treatment on the GINA guidelines within 3 months before randomisation.
Birch or tree pollen‑triggered asthma attacks – a known history of asthma worsening after exposure to birch or related tree pollen.
Recent asthma worsening – any asthma flare‑up in the past 3 months that needed emergency care, hospitalisation, or a short course of oral steroids.
Reduced lung function – measured as FEV1 (the amount of air you can force out in one second) less than 70 % of the expected value at screening or before randomisation.
Ongoing sublingual immunotherapy (SLIT) with birch or related tree pollen – more than 1 month of such treatment in the past 5 years, or any SLIT with birch or related pollen in the past 12 months.
Subcutaneous immunotherapy (SCIT) with birch or related tree pollen – treatment that reached the maintenance dose in the past 5 years, or any SCIT with birch or related pollen in the past 12 months.
Ongoing use of any other allergy immunotherapy product.

Where you can join this trial?

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Other Sites

Site Name	City	Country	Status
Apzbqah	STRASBOURG, Alsace	France

Trial status

Country	Status	Recruitment Start
France	Not yet recruiting	07.09.2026

Trial locations

Investigated Drugs:

Betula Pendula Pollen Extract is a preparation made from the pollen of the birch tree (Betula pendula). In this study it is given by inhalation as a lyophilized (freeze‑dried) powder. The extract is used as a background exposure to mimic the natural birch pollen environment that participants would normally encounter, helping researchers see how the test treatment works under realistic conditions.

Tree SLIT-tablet is a small tablet that is placed under the tongue (sublingual use) and slowly dissolves. It contains a standardized extract of birch pollen (Betula verrucosa) and is designed to teach the immune system to become less reactive to birch pollen. By taking this tablet regularly for at least 16 weeks, the trial aims to reduce the severity of allergic rhinitis and eye symptoms in teenagers who are allergic to birch pollen.

Investigated Diseases:

Birch pollen‑induced allergic rhinitis – This condition is an inflammation of the nasal lining caused by exposure to birch pollen. Symptoms typically include a runny or blocked nose, sneezing, and itching inside the nostrils. The reaction begins shortly after inhaling pollen and can last for several weeks during the pollen season. Over time, repeated exposure may lead to a more persistent nasal congestion and increased sensitivity to other allergens. The severity can range from mild discomfort to moderate or severe blockage that interferes with daily activities.

Birch pollen‑induced allergic rhinoconjunctivitis – This disease combines the nasal inflammation of allergic rhinitis with irritation of the eyes caused by birch pollen. Affected individuals experience watery, red, and itchy eyes along with the typical nasal symptoms. Symptoms start soon after pollen exposure and continue throughout the pollen season. Repeated episodes can make the eyes more reactive, leading to longer periods of discomfort. The condition may affect concentration and comfort during daily tasks, especially in environments with high pollen counts.

Trial ID:

2026-526861-88-00

Protocol code:

TT-07

Trial Phase:

Therapeutic confirmatory (Phase III)

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Efficacy of Tree SLIT-tablet and Betula pendula pollen extract in adolescents (12‑17) with allergic rhinitis/rhinoconjunctivitis caused by birch pollen

What is this study about?

Who Can Join the Study?

Who Cannot Join the Study?