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Study of sublingual birch pollen extract (SLI-RX-BET) in different doses for patients with moderate to severe allergic rhinitis caused by birch pollen

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What is this trial about?

A plain-language summary of the goals, design and what participants do

This clinical trial focuses on treating patients with allergic rhinitis and rhinoconjunctivitis caused by birch pollen. These conditions cause symptoms like nasal congestion, runny nose, and eye irritation during birch pollen season. The study tests a medication called SLI-RX-BET, which is given as a spray under the tongue (sublingual spray) and contains birch pollen extract.

The purpose of this study is to find the most effective and safest dose of SLI-RX-BET for treating birch pollen allergies. The medication will be tested in three different strengths (low, medium, and high dose), and some participants will receive a placebo. The treatment involves daily use of the spray for approximately 10 months.

During the study, participants will need to track their allergy symptoms and use of additional medications during the birch pollen season. The treatment is specifically designed for people who have experienced moderate to severe allergic symptoms from birch pollen for at least two years. The medication aims to help reduce allergy symptoms and decrease the need for other allergy medications.

The research process

The trial runs in 5 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Initial treatment phase

    You will begin treatment with a sublingual spray (medication applied under the tongue) containing either birch pollen extract or placebo

    The spray will be one of three possible strengths: low dose, medium dose, or high dose of birch pollen extract, or a placebo solution without active substance

    The spray should be used as directed under the tongue

  2. Step 2

    Daily symptom recording

    You will need to record your allergy symptoms daily in an electronic diary

    The diary will track both nasal symptoms (affecting the nose) and eye symptoms

    You will also need to record any additional allergy medications used for symptom relief

  3. Step 3

    Quality of life assessment

    You will complete a quality of life questionnaire about how allergies affect your daily activities

    You will rate your overall discomfort from allergy symptoms on a scale from 0 to 10

  4. Step 4

    Nasal testing

    You will undergo a nasal provocation test where small amounts of birch pollen extract are applied to your nose

    This test will be performed before and after the treatment period to measure any changes in your allergic response

  5. Step 5

    Monitoring period

    Your symptoms will be closely monitored during the birch pollen season

    Special attention will be given during the peak birch pollen period

    Any side effects or reactions to the treatment will be recorded

Who can join the trial?

8 criteria

  • Must sign and date the informed consent form before any study procedures begin
  • Must be between 18 and 65 years old when signing the consent form
  • Must have had moderate-to-severe allergic rhinitis (hay fever affecting nose and eyes) caused by birch pollen for at least 2 years. Patients can either have: - Well-controlled mild-to-moderate asthma, or - No asthma
  • For patients with asthma: Must have a lung function test (FEV1) showing breathing capacity greater than 70% of normal value
  • Must show confirmed allergy to birch pollen through: - Positive skin prick test (showing a raised bump of 3mm or larger) - Blood test showing specific antibodies to birch pollen - History of significant allergy symptoms during birch pollen season - Positive response to nasal testing with birch pollen extract
  • Must be able to understand and follow instructions from study staff
  • Must be able to complete an electronic diary to record symptoms and medication use
  • Must have laboratory test results within normal range or any abnormal results deemed not medically significant

Who cannot join the trial?

15 criteria

  • Previous participation in any clinical trial within the last 30 days
  • History of severe allergic reactions or anaphylaxis (life-threatening allergic reactions)
  • Current use of medications that could interfere with the study treatment
  • Pregnancy or breastfeeding
  • Serious heart, liver, or kidney disease
  • Active autoimmune diseases (conditions where the immune system attacks healthy body tissues)
  • Current cancer or history of cancer in the past 5 years
  • Severe asthma or poorly controlled asthma
  • History of substance abuse in the past 2 years
  • Mental health conditions that could affect study participation
  • Recent major surgery (within 3 months)
  • Active infections or fever
  • Known allergies to any components of the study medication
  • Use of immunosuppressive drugs (medications that weaken the immune system)
  • Chronic respiratory conditions other than allergic rhinitis
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Investigated drugs

SLI-RX-BET is a sublingual immunotherapy treatment, which means it is administered under the tongue. It is designed to help patients who are allergic to birch pollen. This type of therapy works by gradually exposing the patient to small amounts of birch pollen allergen to help their immune system become less sensitive to it over time. The goal is to reduce allergic symptoms and the need for additional allergy medications when exposed to birch pollen. This immunotherapy represents a more targeted approach to treating birch pollen allergies compared to traditional antihistamines or other allergy medications that only treat symptoms. Instead, it aims to modify the body's immune response to the allergen itself.

What is already known about the treatment

SLI-RX-BET – A sublingual immunotherapy medication designed for treating moderate to severe allergic rhinitis and rhinoconjunctivitis caused by birch pollen allergies. This treatment is administered under the tongue and works by gradually exposing the immune system to small amounts of birch pollen allergens, helping to build tolerance and reduce allergic reactions over time. The medication belongs to the class of allergen-specific immunotherapy drugs and operates by modifying the immune response at the molecular level, shifting from an allergic response to a tolerance response. Currently undergoing Phase II-III clinical trials to determine optimal dosing and efficacy in patients who have experienced birch pollen allergies for at least two years.

Investigated diseases

  • Allergic rhinitis

    A condition where the immune system reacts to airborne substances like pollen, causing inflammation of the nasal passages. It causes symptoms such as sneezing, runny nose, nasal congestion, and itchy nose. The condition often affects the eyes as well, leading to watery, itchy, and red eyes (rhinoconjunctivitis). When triggered by birch pollen specifically, symptoms typically occur during the birch tree pollination season. The condition is persistent and can significantly affect daily activities and sleep quality.

  • Rhinoconjunctivitis

    A combination of rhinitis and conjunctivitis, where both the nasal passages and eyes are affected by an allergic reaction. The condition causes inflammation of the nasal membranes and the conjunctiva of the eyes. Symptoms include itchy, watery eyes, eye redness, along with nasal congestion, sneezing, and runny nose. The symptoms typically occur when exposed to specific allergens like pollen.

Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IVTrial ID2024-517520-19-00Protocol codeSL-3P2AEstimated enrolment472 patientsSponsorROXALL Medizin GmbH

sourced from the EU Clinical Trials Register and site verification

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