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Dose‑finding trial of a mannan‑conjugated Phleum pratense/Dactylis glomerata allergoid vaccine in patients with grass‑pollen allergic rhinitis or rhinoconjunctivitis

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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 grass pollen induced allergic rhinitis or rhinoconjunctivitis, a condition that causes sneezing, a runny or blocked nose, and itchy, watery eyes when a person is exposed to grass pollen. The investigation will test a new allergy vaccine called polymerised mannan-conjugated allergoid Dactylis glomerata/Phleum pratense (code name EP-088_MG58) that is given subcutaneously – meaning the medicine is injected just under the skin. The main goal of the trial is to find which of two dose strengths provides the best relief of symptoms while remaining safe.

Participants will be randomly assigned to receive either a low‑dose, a high‑dose, or a placebo (a harmless substance that looks the same as the vaccine) in a series of injections spread over several weeks. After the dosing period, they will be followed throughout the grass pollen season and asked to note each day how severe their symptoms are and whether they need any allergy medication. The key result the study will look at is the average daily Combined Symptom and Medication Score (CSMS), a single number that combines the intensity of symptoms with the amount of rescue medicine used, to see how well the vaccine works compared with the placebo. Safety checks will be performed throughout the study.

The research process

The trial runs in 4 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Randomization and first injection

    After joining the trial you are assigned to one of two concentrations of the investigational product: 3000 mTU/mL or 9000 mTU/mL.

    The product is given as a subcutaneous injection (injection under the skin) on the day of the first visit.

    The exact amount of the injection follows the study protocol; the unit mTU (million therapeutic units) is used to describe the strength of the allergen preparation.

  2. Step 2

    Subsequent injections

    You receive additional subcutaneous injections of the same concentration at the times defined by the study schedule.

    Each injection is administered by study staff during scheduled clinic visits.

    The frequency and total number of injections are determined by the trial protocol and are the same for all participants in the same concentration group.

  3. Step 3

    Daily symptom and medication recording

    During the peak grass pollen season in 2027 you record each day the severity of nasal and eye symptoms and any rescue medication you take.

    The information is entered in a diary or electronic device provided by the study.

    These records are used to calculate the combined symptom and medication score (CSMS), the primary outcome of the trial.

  4. Step 4

    Final assessment

    After the pollen season you attend a final visit where study staff review your symptom diary and perform a clinical evaluation.

    The data are analysed to compare the effectiveness and safety of the two concentrations.

    You receive a summary of the study results and any follow‑up instructions.

Who can join the trial?

14 criteria

  • Age: You must be between 18 and 64 years old.
  • Kidney and liver health: Blood tests must show normal kidney and liver function. Small differences that are not serious (grade 2 or lower) are allowed, but larger problems mean you cannot join.
  • Allergy blood test (specific IgE): A blood test must show a certain level of antibodies (IgE) against grass pollen (Phleum pratense) – at least 0.7 kU/L. IgE are proteins that the immune system makes when you are allergic.
  • Pregnancy test for women who could become pregnant: A blood test (and later a urine test) must show that you are not pregnant.
  • Signed consent: You must sign and date an Informed Consent Form, confirming that you understand the study and agree to take part.
  • Overall health: You should be in good physical and mental health.
  • History of moderate or severe grass‑pollen allergy: You need a medical record showing that you have had moderate to severe allergic rhinitis (runny, itchy nose) or rhinoconjunctivitis (nose plus eye symptoms) caused by grass pollen for at least two past pollen seasons.
  • Previous allergy medication use: You must have used allergy medicines for at least two grass‑pollen seasons before joining the study.
  • Positive skin prick test: A doctor must perform a skin prick test that shows a small raised bump (wheal) at least 3 mm wide when grass pollen is applied, a similar reaction to a histamine control, and a tiny or no reaction (<2 mm) to a saline control. This test checks if your skin reacts to the allergen.
  • Contraception for women who could become pregnant: You must agree to use a highly effective birth‑control method (such as hormonal pills, implants, intrauterine device, tubal ligation, or a partner who has had a successful vasectomy) and have a negative urine pregnancy test.
  • Women who cannot become pregnant: If you are pre‑menarche (haven’t started periods), have had a hysterectomy, tubal ligation, or are post‑menopausal (no periods for 12 months), you are eligible.
  • Controlled allergic asthma: You must have a diagnosis of allergic (extrinsic) bronchial asthma that is well‑controlled according to the Global Initiative for Asthma (GINA) guidelines (steps 1‑3) and this must have been confirmed within the last four weeks and remain controlled during the trial.
  • Lung function criteria: If you have any breathing disorder such as asthma or COPD, your lung test results must show at least 80 % of the normal value for either forced expiratory volume in one second (FEV1) or peak expiratory flow (PEF). These tests measure how well you can breathe out air.
  • Allergy symptom score (CSMS): During a screening period, you must have a moderate to severe level of allergy symptoms measured by the Combined Symptom and Medication Score (CSMS), with a score between 1.3 and 5.5 on the worst 14‑day period out of 30 days.

Who cannot join the trial?

34 criteria

  • Participating in another clinical trial now or within 30 days, or not having a sufficient wash‑out period (at least 5 half‑lives) from a previous investigational drug.
  • Having a positive skin test (SPT) to other allergens such as Alternaria mold, house dust mites, cat or dog dander when those allergies are clinically important or you are exposed to them.
  • Having had a severe systemic allergic reaction (grade III/IV) or anaphylaxis to foods (e.g., peanuts, shellfish), bee/wasp stings, or medicines (e.g., penicillin).
  • Being allergic to any ingredient (excipients) in the study drug or placebo.
  • Having non‑allergic (intrinsic) asthma.
  • Having allergic asthma that is only partly controlled or uncontrolled, according to the GINA asthma guidelines, within 4 weeks before screening or during treatment.
  • Having allergic asthma, emphysema, or other lung problems with a forced expiratory volume in 1 second (FEV1) or peak expiratory flow (PEF) less than 80 % of the normal value.
  • Having a recent upper or lower respiratory infection (within the past 2 weeks) or a recent flare‑up of lung disease (within the past 4 weeks).
  • Having serious kidney disease or chronic liver disease.
  • Having an active cancer, or a history of cancer in the past five years.
  • Having a severe autoimmune disease.
  • Receiving allergy shots (immunotherapy) with grass pollen in the last 5 years.
  • Having immune system problems such as immunosuppression or immunopathies.
  • Receiving any vaccination during the treatment period, except flu or COVID‑19 vaccines.
  • Using systemic immunosuppressive medicines (e.g., oral steroids, methotrexate, cyclosporine A).
  • Having any other major inflammatory disease, either acute or chronic.
  • Having other serious chronic illnesses such as severe heart failure, heart insufficiency, active stomach ulcer, inflammatory bowel disease, uncontrolled diabetes, etc.
  • Taking antidepressant or antipsychotic drugs that have strong antihistamine effects (e.g., tricyclic antidepressants, mirtazapine, quetiapine).
  • Receiving or planning to receive biologic therapies (therapeutic antibodies), mast‑cell stabilizers, or anti‑leukotriene drugs.
  • Taking beta‑blocker or ACE‑inhibitor medications.
  • Having active tuberculosis.
  • Having any condition that makes the use of adrenaline unsafe (including an overactive thyroid).
  • Currently receiving allergy shots for grass pollen or any other allergen.
  • Testing positive for HIV, hepatitis B, or hepatitis C antibodies.
  • Being pregnant, breastfeeding, or able to become pregnant and not using a highly effective birth‑control method.
  • Using systemic or nasal steroids or antihistamine medicines within the required time before the trial (except routine asthma control medication).
  • Keeping a diary for fewer than 14 days during the 30‑day pre‑treatment observation period.
  • Having a skin‑test (CAP) class 2 or higher (IgE ≥ 0.7 kU/L) to Alternaria mold, or having laboratory values for kidney or liver function that are higher than grade 2 according to FDA guidance and remain abnormal after a repeat test.
  • Experiencing an acute allergic rhinitis or rhinoconjunctivitis caused by other environmental allergens during the observation period.
  • Having any personal or financial relationship with the sponsor, CRO, or investigator that could influence the study.
  • Being unable to understand the study instructions or documents.
  • Being judged by the investigator as unlikely to follow the study rules (e.g., known alcohol or drug abuse, serious psychiatric disorder, unwillingness to give consent or follow requirements).
  • Being under legal custody or institutional commitment by court or administrative order.
  • Not having access to a smartphone or tablet (iOS or Android) needed for the study diary (paper diary only allowed in rare technical cases).
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Investigated drugs

  • Mometasone nasal spray

    is a steroid spray used in the nose to reduce inflammation and relieve symptoms of allergic rhinitis such as sneezing, runny nose, and congestion. In the trial it was allowed as a background medication for participants who needed ongoing nasal steroid therapy.

  • Budesonide nasal spray

    is another nasal steroid that helps calm inflamed nasal passages and eases allergy symptoms. Participants could continue using it during the study if it was part of their regular treatment.

  • Bilastine tablets

    are oral antihistamine pills that block the action of histamine, a chemical that causes itching, sneezing, and watery eyes in allergies. They were permitted as a background medication for people who required daily allergy relief.

  • Triamcinolone acetonide nasal spray

    is a steroid spray that reduces swelling in the nasal lining, helping to control nasal allergy symptoms. It could be used by participants as part of their usual care.

  • Grass pollen skin‑prick test solution (Phleum pratense)

    is a small amount of grass pollen extract applied to the skin to check if a person is allergic to grass pollen. It was used in the study to confirm participants’ allergy status.

  • Emedastine eye drops

    are eye‑drop medication that relieves itchy, red, and watery eyes caused by allergic reactions. Participants could continue using them if they already needed eye‑drop treatment.

What is already known about the treatment

  • Mometason ratiopharm 50 µg/Sprühstoß Nasenspray

    This nasal spray is sprayed into the nose, delivering a fine suspension of mometasone furoate. It is an approved prescription medicine used to relieve nasal allergy symptoms such as congestion and itching. The drug works by reducing inflammation in the nasal lining, acting as a steroid that blocks substances that cause swelling. It belongs to the class of corticosteroid nasal sprays.

  • Budes 64 µg/Sprühstoß Nasenspray

    This product is a nasal spray that delivers budesonide suspension directly into the nostrils. It is widely used and approved for treating allergic rhinitis and other nasal inflammatory conditions. Budesonide reduces swelling by binding to steroid receptors and lowering the release of inflammatory chemicals. It is classified as an inhaled corticosteroid.

  • Allegra Allergietabletten 20 mg

    The tablets are taken by mouth to relieve allergy symptoms such as sneezing, runny nose, and itchy eyes. Bilastine is an over‑the‑counter antihistamine that blocks the action of histamine, a substance that causes allergy signs. By preventing histamine from attaching to its receptors, it reduces itching and swelling. It belongs to the second‑generation antihistamine group.

  • NASACORT Nasenspray 55 µg/Dosis

    This nasal spray contains triamcinolone acetonide, which is sprayed into each nostril as a suspension. It is a prescription medication for allergic rhinitis and nasal inflammation. The steroid works by calming the immune response in the nasal tissue, lowering swelling and mucus. It is a corticosteroid nasal spray.

  • AVAMYS Nasenspray 27.5 µg/spray

    This nasal spray delivers fluticasone furoate into the nose as a fine mist. It is approved for daily use to control symptoms of allergic rhinitis and nasal congestion. Fluticasone furoate acts as a steroid, decreasing the activity of cells that cause inflammation in the nasal passages. It is part of the inhaled corticosteroid class.

  • Bilaxten Augentropfen 6 mg/ml

    The eye drops are placed directly into the eyes to treat allergic eye irritation. Bilastine in the drops blocks histamine receptors on the eye surface, reducing redness, itching, and watery eyes. By stopping histamine from acting, the drops calm the allergic response. They are classified as antihistamine eye drops.

Investigated diseases

  • Allergic rhinitis

    It is an inflammation of the nasal lining caused by an allergic reaction to airborne substances such as grass pollen. Symptoms start with sneezing, a runny or blocked nose, and itching. With continued exposure, the nasal lining becomes more swollen and mucus production increases. The condition often worsens during the pollen season and improves when the allergen is removed. Repeated seasonal exposure can make the symptoms return each year.

  • Allergic rhinoconjunctivitis

    This condition combines the nasal symptoms of allergic rhinitis with eye irritation caused by the same allergen. After inhaling grass pollen, the eyes become red, itchy, and watery. Ongoing exposure leads to increased swelling of the eye surface and more discharge. Symptoms typically peak during the height of the pollen season and lessen when pollen levels drop. Repeated seasonal episodes can make the eyes more sensitive over time.

Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IVTrial ID2025-524580-21-00Protocol codeMG58-SIT-084Estimated enrolment450 patientsSponsorInmunotek S.L.

sourced from the EU Clinical Trials Register and site verification

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