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Study on the Effectiveness and Safety of Phleum Pratense Pollen Extract for Patients with Moderate-to-Severe Grass Pollen Allergy

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What is this trial about?

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

This clinical trial is focused on studying the effectiveness and safety of a treatment for people who have been suffering from moderate-to-severe allergic rhinitis or rhinoconjunctivitis due to grass pollen for at least two years. The treatment being tested is called SULGEN® Spray Phleum pratense, which is a type of sublingual immunotherapy. This means the treatment is administered as a spray under the tongue. The study aims to find the most effective and well-tolerated dose of this spray, balancing its benefits and risks.

Participants in the study will receive either the SULGEN® Spray Phleum pratense or a placebo, which looks and tastes like the real treatment but does not contain the active ingredient. The study will compare the effects of the treatment and the placebo on symptoms and the need for additional medication during the peak grass pollen period. The study will also look at how the treatment affects the quality of life and the number of days participants experience no symptoms or severe symptoms.

The trial will involve regular assessments to monitor the participants' symptoms and any changes in their condition. This includes using a nasal provocation test, which involves exposing the nose to the allergen to see how it reacts. The study is expected to run until October 2025, with recruitment starting in November 2023. The goal is to provide valuable information on how well the SULGEN® Spray Phleum pratense works for people with grass pollen allergies.

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 assessment

    Upon joining the study, an initial assessment is conducted to confirm eligibility. This includes a skin prick test using solutions such as timothy grass pollen extract and phleum pratense pollen extract to verify sensitization.

    A positive skin prick test is indicated by a wheal diameter of at least 3 mm, with a negative control less than 2 mm and a positive histamine control of at least 3 mm.

  2. Step 2

    Baseline evaluation

    A baseline evaluation is performed to record initial symptoms and medication use. This involves completing an electronic diary for self-evaluation of symptoms and rescue medication.

  3. Step 3

    Treatment phase

    The treatment phase involves the administration of SULGEN® Spray Phleum pratense in varying doses. The spray is used sublingually, meaning it is applied under the tongue.

    The dosage is adjusted to determine the most effective and best-tolerated dose. The treatment aims to improve the Combined Symptom and Medication Score (CSMS) during the peak grass pollen period.

  4. Step 4

    Monitoring and evaluation

    Throughout the trial, symptoms and medication use are monitored using the electronic diary. This helps assess the efficacy of the treatment compared to a placebo.

    Regular assessments are conducted to evaluate changes in symptoms and quality of life using tools like the Rhinoconjunctivitis Quality of Life Questionnaire (RQLQ) and Visual Analogue Scale (VAS).

  5. Step 5

    Final assessment

    At the end of the trial, a final assessment is conducted to compare pre-treatment and post-treatment results.

    The primary endpoint is the difference in mean CSMS during the peak grass pollen period between the active treatment and placebo groups.

Who can join the trial?

12 criteria

  • Patients must have signed and dated the informed consent form before any study-specific examination.
  • Participants can be female or male and must be between 18 and 65 years old at the time of signing the informed consent form.
  • Patients should have had **moderate-to-severe allergic rhinitis/rhinoconjunctivitis** due to grass pollen for at least two years. This condition involves symptoms like a runny or blocked nose and itchy or watery eyes.
  • Patients can have mild-to-moderate asthma that is well-controlled, or they can have no asthma at all. Asthma is a condition that affects the airways in the lungs, making it hard to breathe.
  • For patients with asthma, their **forced expiratory volume (FEV1)** in one second should be more than 70% of the predicted normal value. FEV1 is a measure of how much air a person can forcefully exhale in one second.
  • Patients must be **sensitized to Phleum pratense pollen**, which means they have an allergic reaction to this type of grass pollen. This is confirmed by:
  • A positive **skin prick test**, which involves placing a small amount of allergen on the skin and pricking it to see if there is a reaction.
  • A blood test showing a certain level of **IgE antibodies** specific to Phleum pratense. IgE antibodies are proteins made by the immune system in response to allergens.
  • A **Retrospective Rhinoconjunctivitis Total Symptom Score (RRTSS)** of 2 or more, based on the most severe days during one of the two grass pollen seasons before joining the study. This score measures the severity of symptoms like sneezing and itchy eyes.
  • A positive response to a **nasal provocation test** with Phleum pratense pollen allergen extract, which involves exposing the nose to the allergen to see if symptoms occur.
  • Patients must be able to understand and use an electronic diary to record their symptoms and any medication they take.
  • Patients must have safety laboratory results that are within the normal range or not considered clinically significant.

Who cannot join the trial?

10 criteria

  • Patients who have not experienced moderate-to-severe **allergic rhinitis** or **rhinoconjunctivitis** due to grass pollen for at least two years. **Allergic rhinitis** is a condition where your nose gets stuffy or runny due to allergies. **Rhinoconjunctivitis** is when both your nose and eyes are affected by allergies.
  • Patients who do not fit the age range specified for the study.
  • Patients who are not willing or able to follow the study procedures.
  • Patients who have other medical conditions that might interfere with the study.
  • Patients who are taking medications that could affect the study results.
  • Patients who are pregnant or breastfeeding.
  • Patients who have participated in another clinical trial recently.
  • Patients who have a history of severe reactions to similar treatments.
  • Patients who have a history of drug or alcohol abuse.
  • Patients who have any other reason that the study doctors believe would make it unsafe or inappropriate for them to participate.
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Investigated drugs

SULGEN® Spray Phleum pratense is a sublingual immunotherapy treatment being tested for its effectiveness and safety in patients with grass pollen allergy. This therapy involves administering a spray under the tongue, which contains extracts from the grass species Phleum pratense, commonly known as Timothy grass. The goal of this treatment is to help the immune system become less sensitive to grass pollen, thereby reducing allergy symptoms and the need for other allergy medications. The trial aims to find the most effective dose that provides the best balance between benefits and potential side effects.

What is already known about the treatment

SULGEN® Spray Phleum pratense – This medication is administered as a sublingual spray, meaning it is applied under the tongue. It is currently being studied in clinical trials to determine its effectiveness and safety for treating moderate-to-severe allergic rhinitis or rhinoconjunctivitis caused by grass pollen. The main therapeutic indication is to alleviate symptoms associated with grass pollen allergies. At the molecular level, it works by gradually desensitizing the immune system to grass pollen allergens, reducing allergic reactions over time. It is classified as an immunotherapy agent, specifically designed to modify the immune response to allergens.

Investigated diseases

Allergic Rhinitis – Allergic rhinitis is a condition characterized by inflammation of the nasal passages due to an allergic reaction, often triggered by pollen, dust, or pet dander. Symptoms include sneezing, nasal congestion, runny nose, and itchy eyes. It can be seasonal, occurring at certain times of the year, or perennial, occurring year-round. The condition is often associated with other allergic disorders, such as asthma or eczema. Over time, symptoms may vary in intensity and can affect daily activities and sleep.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IVTrial ID2023-505880-35-00Estimated enrolment512 patientsSponsorROXALL Medizin GmbH

sourced from the EU Clinical Trials Register and site verification

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