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Efficacy and safety of allergenic extract of Olea europaea pollen polymerized with glutaraldehyde in patients with olive pollen allergy, including 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 individuals who experience allergic rhinitis and rhinoconjunctivitis caused by olive pollen, and who may also have mild asthma. The treatment being tested is a vaccine‑like preparation called Olea europaea pollen polymerized extract, which is given as a small subcutaneous injection. A matching injection that does not contain the active pollen material is used as a placebo for comparison.

The purpose is to determine whether this pollen‑based immunotherapy can lower symptoms and reduce the need for rescue medicines during the peak olive‑pollen season. Participants will receive a series of injections over several months, record daily symptoms and medication use in a simple diary, and attend regular visits where safety checks such as injection‑site inspection, vital‑sign measurements, and basic blood tests are performed. The study will also monitor any asthma attacks or additional health visits that occur.

The research process

The trial runs in 7 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Randomization and assignment

    After you join the study, you will be randomly assigned to receive either the active olive pollen extract or a placebo that looks the same.

    The assignment is double‑blind, which means neither you nor the study staff will know which product you receive.

  2. Step 2

    First subcutaneous injection

    You will receive a single subcutaneous (under the skin) injection of 0.5 ml of the assigned solution.

    The active product is a polymerized olive pollen extract with a concentration of 10,000 TU/mL; the placebo contains no active ingredients.

  3. Step 3

    Subsequent injections during treatment phase

    You will continue to receive additional subcutaneous injections of 0.5 ml according to the study schedule.

    Each injection will be administered in the same manner as the first one, and the product (active or placebo) will remain unknown to you.

  4. Step 4

    Daily symptom and medication diary

    Throughout the entire olive pollen season, you will record your daily nasal and eye symptoms, any asthma symptoms, and the use of rescue medication in the electronic ITK Diary Card application.

    The diary data are used to calculate symptom scores and medication scores that compare the active and placebo groups.

  5. Step 5

    Scheduled study visits

    You will attend several visits: a baseline visit before starting treatment, a visit after the treatment phase, a visit during the peak pollen season, and a final end‑of‑trial visit.

    At each visit you will undergo a physical examination, measurement of vital signs (such as blood pressure and heart rate), and laboratory tests including blood count and chemistry.

    If you have asthma or other lung function abnormalities, pulmonary function testing will be performed.

    Blood samples will be taken to measure specific immunoglobulins (IgE and IgG4) and to assess allergen sensitization using ALEX technology.

  6. Step 6

    Safety monitoring

    After every injection you will be observed for any local reactions at the injection site and for systemic reactions such as fever or rash.

    You are instructed to report any unexpected adverse events promptly to the study team.

  7. Step 7

    Final evaluation and end of trial

    At the end‑of‑trial visit the collected diary data, symptom scores, asthma control questionnaire results, quality‑of‑life questionnaires, and laboratory results will be compared between the active and placebo groups.

    The comparison will include the number of symptom‑free days, frequency of asthma exacerbations, use of rescue medication, and any healthcare contacts related to allergy or asthma.

Who can join the trial?

18 criteria

  • Be between 12 and 64 years old, including both ages.
  • Have had allergic rhinitis or rhinoconjunctivitis (runny nose, sneezing, itchy eyes) caused by olive pollen that needed regular use of nasal steroid spray, with or without antihistamine pills, during the last pollen season; your symptom score must have been at least 2 on a 0‑to‑6 scale.
  • Provide a signed and dated Informed Consent Form confirming you understand the study.
  • Be in good overall physical and mental health as judged by the study doctor.
  • Have a confirmed olive pollen allergy based on all three of the following:
    • History of moderate‑to‑severe symptoms for at least the last two olive pollen seasons.
    • Use of allergy medicines (like nasal steroids or antihistamines) for at least those two seasons.
    • A positive skin prick test to olive pollen (a small bump on the skin at least 5 mm wide) performed within the past year, with a valid control reaction to histamine.
    • If you are a woman who could become pregnant (childbearing potential), you must agree to use a highly effective birth‑control method such as hormonal pills, hormonal IUD, hormonal implant, hormonal injection, tubal ligation, or have a partner who has had a successful vasectomy.
    • Women who cannot become pregnant (e.g., not yet started periods, have had a hysterectomy, are post‑menopausal, or have had permanent sterilisation) are also eligible.
    • If you have asthma, it must be a mild‑to‑moderate, well‑controlled form diagnosed within the past year, following standard asthma guidelines (GINA steps 1‑3).
    • If you have any breathing‑related lung problem (such as asthma or COPD), your lung function must be at least 80 % of the normal value, measured by FEV1 (the amount of air you can force out in one second) or Peak Expiratory Flow (the highest speed of breathing out).
    • Laboratory tests must show:
      • Normal kidney and liver function (small, non‑significant differences are allowed after repeat testing).
      • Specific IgE antibodies against olive pollen of 3.5 kU/L or higher, measured within the past year.
      • A negative pregnancy test (blood) at screening, confirmed by a urine test if you are a woman of childbearing potential.
      • You should mainly be allergic to olive pollen only (monosensitised). If you are also allergic to other airborne allergens, you may still join if:
        • Allergy to dust mites is present but the IgE level is less than 3.5 kU/L.
        • Allergy to animal dander is present only with occasional exposure; frequent exposure requires a negative skin test.
        • Allergy to other pollens is allowed only if their pollen season does not overlap with the study period; for grass pollen, IgE to the major components (Phl p 1 and Phl p 5) must be below 0.30 kUA/L.
        • Allergy to the mold Alternaria alternata is allowed if the IgE level is less than 3.5 kU/L.

Who cannot join the trial?

33 criteria

  • Participating in another clinical trial, or having taken part in a trial within the past 30 days.
  • Having a known allergy (hypersensitivity) to any ingredient (excipient) in the study medication or the placebo (the inactive substance used for comparison).
  • Having uncontrolled asthma – meaning asthma that is not well‑controlled, with frequent symptoms, frequent use of rescue inhalers, limited activity, nighttime symptoms, or two or more flare‑ups per year needing oral steroids, or a severe flare‑up requiring hospitalization.
  • Having a lung function test result (FEV1) less than 80 % of the normal value expected for your age, sex, and size, even though you are on appropriate medication.
  • Having severe asthma or asthma that requires the highest treatment steps (Step 4 or Step 5) according to the asthma guideline GINA 2026.
  • Having symptoms of an upper or lower respiratory infection (like a cold, bronchitis, or pneumonia) within two weeks before the screening visit, or having a recent worsening of lung problems within four weeks.
  • Having a serious kidney problem (renal disease) or a serious liver problem (hepatic disease).
  • Having an active cancer, or a history of cancer within the past five years.
  • Having a severe autoimmune disease (a condition where the immune system attacks the body’s own tissues).
  • Having an immune system disorder that weakens immunity (immunodeficiency, immunosuppression, or other immune‑related conditions).
  • Having uncontrolled chronic illnesses such as severe heart failure, serious heart disease, active stomach ulcers, inflammatory bowel disease, or uncontrolled diabetes.
  • Having any condition that makes using adrenaline (epinephrine) unsafe, such as an overactive thyroid (hyperthyroidism).
  • Having active tuberculosis (a serious lung infection).
  • Testing positive for HIV‑1/2, hepatitis B, or hepatitis C antibodies (signs of these infections).
  • Being pregnant, breastfeeding, or being a woman who could become pregnant and is not using a highly effective birth control method.
  • Using strong immune‑suppressing medicines (like methotrexate or cyclosporine) or having had a blood transfusion within one month before screening.
  • Being treated with biologic drugs (such as monoclonal antibodies), mast cell stabilizers, or anti‑leukotriene medications.
  • Taking beta‑blocker medicines or ACE inhibitors (common blood pressure drugs).
  • Using certain antidepressant or antipsychotic medicines that have strong antihistamine effects (for example, tricyclic antidepressants).
  • Using systemic (whole‑body) or nasal steroids or antihistamines within the required wash‑out period before screening, except for regular asthma maintenance medication.
  • Missing a test that measures specific antibodies to olive pollen (olive pollen‑specific IgE).
  • Currently receiving allergy shots (allergen immunotherapy) for any allergen.
  • Having a strong allergy to house dust mites with a specific IgE level of 3.5 kU/L or higher.
  • Having a strong allergy to animal skin cells or dander with relevant exposure.
  • Having a strong allergy to the mold Alternaria alternata with a specific IgE level of 3.5 kU/L or higher.
  • Having a strong allergy to grass pollen, shown by a molecular test with specific IgE to the main grass proteins (Phl p 1 or Phl p 5) of 0.30 kUA/L or higher.
  • Having abnormal kidney or liver lab test results at screening that remain abnormal after a repeat test (at least 7 days later).
  • Having significant allergy symptoms caused by other environmental allergens during the study period.
  • Having any financial or personal relationship with the study sponsor or investigator that could affect participation.
  • Being unable to understand the study procedures or paperwork.
  • Being considered unlikely to follow the study rules, such as due to substance abuse, serious mental health problems, or unwillingness to comply.
  • Being confined in a jail, prison, or other institutional setting by legal order.
  • Having a history of severe whole‑body allergic reactions (Grade III‑IV) or anaphylaxis (a life‑threatening reaction) to foods, insect stings, or medications.
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Investigated drugs

Olea europaea pollen polymerized extract suspension for injection
This is a specially prepared solution that contains tiny pieces of olive tree pollen that have been treated so they are less likely to cause a strong allergic reaction. It is given as a subcutaneous injection (under the skin) in a series of doses over time. The purpose of the treatment is to help the immune system become less sensitive to olive pollen, which should reduce the symptoms of allergic rhinitis or rhinoconjunctivitis, such as runny nose, sneezing, itchy eyes, and may also help people who have mild‑to‑moderate asthma triggered by olive pollen. The therapy is being tested to see if it can safely and effectively lessen these allergy symptoms compared with a placebo.

What is already known about the treatment

  • Olea europaea pollen polymerized extract 10,000 TU/mL suspension for injection

    This product is given as a 0.5 ml subcutaneous injection of a liquid suspension. It is an approved allergen immunotherapy listed under ATC code V01AA05 and is used in clinical practice for treating pollen allergies. The main use is for moderate‑to‑severe allergic rhinitis or rhinoconjunctivitis caused by olive pollen, with or without mild‑to‑moderate asthma. It works by delivering polymerized olive pollen proteins that slowly stimulate the immune system, helping it shift from an allergic IgE response to a more tolerant IgG response, and it belongs to the class of subcutaneous allergen immunotherapy (tree‑pollen extract).

  • Same solution and presentation that active treatment but without active ingredients

    This preparation is administered in the same way as the active drug, a 0.5 ml subcutaneous injection of a clear solution, but it contains no allergenic extract. It serves as a placebo control in clinical studies and has no therapeutic effect or approved medical use. Its purpose is to mimic the appearance and administration method of the active product so that any differences in outcomes can be attributed to the active ingredient. It is classified as an inert placebo used for blinding in trials.

Investigated diseases

  • Allergic rhinitis (olive pollen‑induced)

    Inflammation of the nasal lining occurs when the immune system reacts to olive pollen, causing sneezing, a runny nose, and nasal congestion. Symptoms appear during the pollen season and usually persist while exposure continues. The severity can range from mild to moderate or severe. The condition is triggered by an allergic response to pollen particles. Nasal symptoms often fluctuate with the amount of pollen in the air.

  • Allergic rhinoconjunctivitis (olive pollen‑induced)

    This disease combines nasal allergy symptoms with eye involvement such as itching, redness, and tearing. It develops when olive pollen contacts both the eyes and nasal passages, provoking an immune reaction. Symptoms are most common during the peak pollen season and vary with pollen levels. Inflammation affects the conjunctiva and nasal mucosa simultaneously. The discomfort typically improves when pollen exposure decreases.

  • Asthma (mild‑to‑moderate)

    Asthma is a chronic lung condition where the airways become narrowed and inflamed, leading to wheezing, shortness of breath, and coughing. Triggers include allergens like olive pollen, exercise, and cold air. In the mild‑to‑moderate form, symptoms are intermittent and often worsen during high pollen periods. The airway narrowing is reversible, allowing normal breathing between episodes. Symptom intensity changes with exposure to triggers and other factors.

Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2026-526390-41-00Protocol codeT517-SIT-092Estimated enrolment120 patientsSponsorInmunotek S.L.

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