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Efficacy and safety of 6‑grass pollen polymerized extracts 30,000 TU/mL and 10,000 TU/mL in adults with grass pollen‑induced allergic rhinitis/rhinoconjunctivitis, with or without mild‑to‑moderate asthma

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What is this trial about?

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

The study focuses on people who have grass pollen‑triggered Allergic rhinitis or rhinoconjunctivitis, which cause sneezing, runny nose, itchy eyes and throat, and may also have mild‑to‑moderate asthma, a condition that makes breathing difficult. Participants may continue using their usual allergy medicines such as a nasal spray containing Mometasone furoate, eye drops with Olopatadine, or oral tablets of Bilastine. The investigational treatment is a vaccine made from polymerized grass pollen extracts given by an injection under the skin (subcutaneous) in two different strengths.

The purpose of the trial is to find out whether this immunotherapy reduces allergy symptoms and the need for rescue medication compared with a dummy injection (placebo). Volunteers will receive a series of injections over several months, keep a simple diary of their daily symptoms and any rescue medication they use, and attend a few routine visits for safety checks such as checking vital signs and basic blood tests.

The research process

The trial runs in 8 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Baseline assessment and randomization

    After joining the study, you will attend a baseline visit where health measurements, blood tests, and lung function (if needed) are performed. the purpose is to record your condition before any treatment.

    Based on the study design, you will be randomly assigned to receive either the 0.5 ml subcutaneous injection of 30,000 TU/mL grass‑pollen extract, the 0.5 ml subcutaneous injection of 10,000 TU/mL grass‑pollen extract, or a placebo injection that looks the same but contains no active ingredient.

  2. Step 2

    First injection and start of treatment phase

    You will receive the first injection under medical supervision. the injection is given under the skin (subcutaneous) in a small volume of 0.5 ml.

    The exact schedule for subsequent injections (how often they are given) is defined by the study protocol but is not detailed in the available information.

  3. Step 3

    Daily symptom and medication diary

    Each day you will record your nose, eye, and breathing symptoms, as well as any rescue medication you use, in the study diary (the ITK Diary Card application). this information is used to calculate the combined symptom and medication scores.

  4. Step 4

    Use of rescue medications

    You may use the following medications if symptoms occur:

    mometasone nasal spray: each spray delivers 50 µg of medication; use as directed by your physician.

    olopatadine eye drops: each dose contains 4 units of medication; use as directed by your physician.

    bilastine tablets: each tablet contains 20 mg of medication; typically taken once daily, but follow the dosing instructions given to you.

  5. Step 5

    Scheduled follow‑up visits

    Throughout the treatment period you will attend study visits at predefined times (for example, before treatment start, after a defined period of treatment, and at the end of the trial). during these visits you will undergo physical examinations, vital‑sign checks, and repeat laboratory tests.

    If you have asthma, lung function testing may be performed at these visits.

  6. Step 6

    Questionnaires and quality‑of‑life assessments

    Before the first injection and again during the peak grass‑pollen season, you will complete questionnaires that evaluate allergy‑related quality of life (RQLQ) and a visual analogue scale (VAS) for symptom severity.

  7. Step 7

    Continuation of treatment until trial end

    You will continue to receive the assigned injection series, record daily symptoms, and use rescue medication as needed until the study concludes on 2027‑12‑31 or until the end‑of‑trial visit, whichever occurs first.

  8. Step 8

    Final end‑of‑trial assessment

    At the end of the trial you will have a final visit that includes the same examinations and laboratory tests performed at baseline, as well as the final symptom scores and quality‑of‑life questionnaires.

Who can join the trial?

13 criteria

  • Age: You must be between 12 and 64 years old, inclusive.
  • Regular allergy medication: During the last grass pollen season you needed regular use of a nasal steroid spray, with or without an antihistamine pill, and your symptom score (called RCSMS) was 2 or higher on a 0‑to‑6 scale.
  • Informed consent: You must sign and date the consent form agreeing to take part.
  • Overall health: The doctor must judge that you are in good physical and mental health.
  • Grass pollen allergy diagnosis: You must have a history of moderate to severe nasal and eye allergy symptoms caused by grass pollen for at least the last two seasons, have taken allergy medicines for at least two grass pollen seasons, and have a positive skin prick test (a small raised bump at least 5 mm) to grass pollen with a positive control (histamine) also showing a bump of at least 5 mm.
  • Women of child‑bearing potential: You must agree to use a highly effective birth‑control method (such as hormonal pills, patches, injections, implants, an intra‑uterine device, tubal ligation, or have a partner who has had a successful vasectomy) and have a negative pregnancy test.
  • Women not of child‑bearing potential: Women who have not started periods, have had a hysterectomy, tubal ligation, or are post‑menopausal (no periods for 12 months) are also eligible.
  • Asthma (if you have it): You must have mild‑to‑moderate asthma that is well‑controlled, defined by standard treatment steps 1‑3, and you must not have severe or uncontrolled asthma; the diagnosis must be recent (within the past year).
  • Lung function: Your breathing test must show at least 80 % of the normal value for either Forced Expiratory Volume in 1 second (FEV1) or Peak Expiratory Flow (PEF). (FEV1 measures how much air you can force out in one second.)
  • Kidney and liver health: Blood tests must show normal kidney and liver function, or only minor, non‑concerning differences that can be repeated and become normal.
  • Allergy blood test (IgE): A blood test must show a specific IgE level to grass pollen of 3.5 kU/L or higher. (IgE is the antibody that causes allergic reactions.)
  • Pregnancy test: Women who could become pregnant must have a negative blood pregnancy test at screening and a confirming urine test at the first study visit.
  • Mostly allergic only to grass pollen: You should not be strongly allergic to many other airborne substances; if you are allergic to dust mites, animals, other pollens, or the mold Alternaria, the specific IgE level for each must be below 3.5 kU/L, and you must meet the additional rules about exposure described above.

Who cannot join the trial?

31 criteria

  • You cannot join if you have taken part in another clinical trial or finished one within the past 30 days.
  • If you are known to be allergic (have hypersensitivity) to any ingredient in the study medicine or the placebo, you are excluded.
  • People with asthma that is not well‑controlled (frequent symptoms, need for rescue inhalers, night symptoms, activity limits, or frequent flare‑ups needing oral steroids, or any severe flare‑up that required a hospital stay) cannot participate.
  • If a lung test called FEV1 (how much air you can force out in one second) is less than 80 % of the normal value for your age, or if a breathing test called PEF (peak flow) is below 80 % of your best level, you are excluded.
  • People with severe asthma that needs the strongest treatment steps (GINA Step 4 or Step 5) are not allowed.
  • If you have had a cold, flu, or any upper or lower respiratory infection in the two weeks before the first study visit, or a worsening of lung problems in the four weeks before screening, you cannot join.
  • Significant kidney disease (renal) or long‑term liver disease (hepatic) excludes you.
  • Anyone with an active cancer, or who has had cancer in the past five years, is not eligible.
  • Severe autoimmune diseases (where the immune system attacks the body) are an exclusion.
  • People with weakened immune systems (immunodeficiency or immunosuppression) are excluded.
  • Uncontrolled serious chronic illnesses such as heart failure, poor heart function, active stomach ulcers, inflammatory bowel disease, or uncontrolled diabetes are reasons to be excluded.
  • If you received allergy shots for grass pollen in the last five years, you cannot take part.
  • Any condition that makes the use of adrenaline (also called epinephrine) unsafe, such as an overactive thyroid (hyperthyroidism), excludes you.
  • Active tuberculosis (TB) is an exclusion.
  • Positive test results for HIV, hepatitis B, or hepatitis C mean you cannot participate.
  • Pregnant or breastfeeding women, and women who could become pregnant but are not using a highly reliable birth‑control method, are excluded.
  • Use of strong immune‑suppressing medicines (such as methotrexate or cyclosporine) or having a blood transfusion within one month before screening disqualifies you.
  • Receiving biologic drugs (like monoclonal antibodies), mast cell stabilizers, or anti‑leukotriene medicines excludes you.
  • Taking beta‑blocker or ACE‑inhibitor blood pressure medicines excludes you.
  • Use of certain antidepressants or antipsychotics that act like strong antihistamines (for example, tricyclic antidepressants) is not allowed.
  • Using systemic (whole‑body) or nasal corticosteroids or antihistamines during the required wash‑out period before screening (except for regular asthma medication) will exclude you.
  • If a test for grass‑pollen‑specific IgE (a blood test for allergy) is missing, you cannot join.
  • Being currently treated with any allergy shots (allergen immunotherapy) for any allergen excludes you.
  • Allergy to house dust mites with a high level (IgE ≥ 3.5 kU/L), to pet dander with relevant exposure, to the mold Alternaria alternata with a high level, or to other seasonal pollens with a high level (IgE ≥ 3.5 kU/L) will exclude you.
  • If your lab results show significant abnormal kidney or liver values at screening and they stay abnormal after a repeat test, you are excluded.
  • If you have important allergic rhinitis or rhinoconjunctivitis caused by other environmental allergens during the study period, you cannot participate.
  • Any financial or personal dependence on the study sponsor or investigator excludes you.
  • If you cannot understand the study procedures or the information sheets, you are not eligible.
  • People who are unlikely to follow the study rules (for example, due to substance abuse, serious mental illness, or unwillingness to comply) are excluded.
  • Being placed in an institution by a court order (judicial or administrative) excludes you.
  • A history of severe whole‑body allergic reactions (Grade III–IV) or anaphylaxis (a life‑threatening allergic reaction) to foods, insect stings, or medicines disqualifies you.
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Investigated drugs

  • Mometasone nasal spray

    is a steroid medication that is sprayed into the nose. It helps reduce swelling and inflammation in the nasal passages, which can relieve symptoms such as a runny or stuffy nose caused by allergies.

  • Olopatadine eye drops

    are used to treat eye irritation caused by allergies. When placed in the eyes, they help calm itching, redness, and watery eyes by blocking the action of substances that cause allergic reactions.

  • Bilastine tablets

    are an oral antihistamine taken by mouth. They work by stopping histamine, a chemical released during an allergic reaction, which helps lessen sneezing, itching, and a runny nose.

  • Grass pollen immunotherapy (10,000 TU)

    is a treatment given as a small injection under the skin. It contains tiny amounts of grass pollen proteins that have been modified to reduce allergic reactions. Over time, this therapy aims to teach the immune system to become less sensitive to grass pollen, reducing allergy symptoms during the pollen season.

  • Grass pollen immunotherapy (30,000 TU)

    is similar to the 10,000 TU version but contains a higher concentration of the modified grass pollen proteins. It is also administered as a subcutaneous injection and is intended to help the body build stronger tolerance to grass pollen, leading to fewer or milder allergy symptoms.

What is already known about the treatment

  • Mometasone furoate

    This nasal spray delivers 50 µg of medication per spray and is applied directly into the nose. It is an approved corticosteroid widely used for allergic rhinitis. It works by binding to glucocorticoid receptors, which reduces inflammation and the release of allergy‑related chemicals. It belongs to the class of nasal corticosteroids.

  • Olopatadine

    The eye‑drop solution (1 mg/ml) is placed in the eyes to relieve allergic eye symptoms. It is an approved antihistamine and mast‑cell stabilizer for allergic conjunctivitis. It blocks H1 histamine receptors and helps keep mast cells from releasing inflammatory substances. It is classified as a topical antihistamine/mast‑cell stabilizer.

  • Bilastine

    This oral tablet (20 mg) is swallowed once daily to treat allergy symptoms. It is an approved second‑generation antihistamine for allergic rhinitis and urticaria. It selectively blocks H1 histamine receptors, preventing the usual allergic reactions. It falls under the class of oral non‑sedating antihistamines.

  • Grass pollen polymerized extract (10,000 TU/mL)

    The suspension is injected under the skin (0.5 ml) as part of allergy immunotherapy. It is an investigational allergen vaccine that has been used in some countries for grass‑pollen allergy. It introduces modified grass‑pollen proteins to the immune system, gradually shifting the response from an IgE‑driven allergy to a more tolerant IgG profile. It is classified as a subcutaneous allergen immunotherapy (allergy vaccine).

  • Grass pollen polymerized extract (30,000 TU/mL)

    This subcutaneous injection (0.5 ml) contains a higher concentration of the same polymerized grass‑pollen proteins. It is also an investigational allergy vaccine used for grass‑pollen‑induced allergic rhinitis/rhinoconjunctivitis, with or without mild asthma. By repeatedly exposing the immune system to the modified allergens, it aims to reduce allergic sensitivity through immune tolerance. It belongs to the class of subcutaneous allergen immunotherapy (allergy vaccine).

Investigated diseases

  • Grass pollen‑induced allergic rhinitis

    It is an inflammation of the nasal lining triggered by exposure to grass pollen. Symptoms start with sneezing, a runny or blocked nose, and itchy nose, and they become worse during the grass pollen season. The condition may persist as long as pollen is present and can fluctuate day to day. Repeated exposure can lead to chronic nasal congestion.

  • Grass pollen‑induced allergic rhinoconjunctivitis

    This condition combines nasal inflammation with irritation of the eyes caused by grass pollen. Patients experience watery, itchy eyes along with typical nasal symptoms, and the signs intensify during peak pollen periods. Symptoms usually improve when pollen levels drop. Ongoing sensitivity can cause the eyes to stay red and uncomfortable throughout the season.

  • Mild‑to‑moderate asthma

    Asthma is a lung disorder where the airways become narrowed and inflamed, leading to coughing, wheezing, and shortness of breath. In the mild‑to‑moderate form, episodes are triggered by allergens such as grass pollen and occur mainly during exposure periods. Symptoms may come and go, worsening during the pollen season and easing when the trigger is avoided. Over time, repeated attacks can increase airway responsiveness.

Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2026-526100-73-00Protocol codeMG01-SIT-093Estimated enrolment171 patientsSponsorInmunotek S.L.

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