Skip to content
Clinical Trials – home

Rare diseases

Investigational molecules

Locations

Our offerNewsroom

Recruiting

Study of the efficacy and safety of depigmented polymerized grass pollen extracts for patients with allergic rhinitis and controlled asthma.

Verified siteInvestigational
Clinical Trials Concierge

Prefer not to search? Our Concierge searches the trials for you.

What is this trial about?

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

This study aims to evaluate the efficacy and safety of grass pollen immunotherapy for individuals living with allergic rhinoconjunctivitis, which is an allergic reaction affecting the nose and eyes, and may occur with or without controlled asthma. The treatment involves the use of Depigoid Grass-Mix and Depigoid FORTE Grass-Mix, which are suspensions for injection containing extracts from various grass pollens. These extracts have undergone a process to remove color and change their structure to be used for subcutaneous use, meaning they are administered by injection under the skin. A placebo will also be used during the investigation.

The research is conducted in different stages. Initially, a phase involves a double-blind process, where neither the participants nor the researchers know who is receiving the active medication or the placebo. During this stage, participants receive regular injections, and their symptoms and use of medications like antihistamines or intranasal corticoids are monitored. This is followed by an open-label phase, where the treatment details are known to everyone involved. This part of the study looks at how the body responds to different amounts of pollen through a conjunctival provocation test, which is a method used to see how the eyes react when exposed to allergens.

The research process

The trial runs in 3 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Initial phase

    Participation begins in a double-blind, randomized, controlled phase. during this time, the treatment received is either one of two grass pollen extracts or a placebo, which is an inactive substance. neither the patient nor the researchers know which substance is being administered.

    The treatment consists of subcutaneous injections, which are administered under the skin. the possible medications are depigoid grass-mix (1000 dpp/ml) or depigoid forte grass-mix (3000 dpp/ml), both in a dose of 0.5 ml.

    Symptoms and the use of medication are recorded using a mobile app. the score ranges from 0 to 6 and includes tracking antihistamine eye drops, oral antihistamines, and intranasal corticoids (nasal sprays to reduce inflammation).

  2. Step 2

    Assessment during peak pollen season

    After receiving at least 8 injections, the effectiveness is evaluated by measuring the combined symptom and medication score during the period of highest grass pollen concentration.

  3. Step 3

    Open-label phase

    The trial transitions to an open-label phase, where the treatment being used is known. the focus is to assess how the treatment changes the amount of allergen needed to trigger a reaction.

    A conjunctival provocation test, which is a test where eye drops containing pollen extracts are used to observe a reaction, is performed to compare results after the pollen season against the initial baseline.

Who can join the trial?

9 criteria

  • You must be at least 5 years old at the time you agree to participate.
  • You must have moderate or severe allergic rhinoconjunctivitis, which is a condition involving hay fever symptoms like sneezing, itching, or watery eyes and redness in the eyes.
  • If you have asthma, your condition must be controlled, meaning your breathing issues are well-managed and stable according to standard medical guidelines.
  • You or your legal representative must sign a document called informed consent, which means you have understood all the details of the study before joining.
  • You or your guardian must own a mobile phone that can run the specific study app and has access to the internet.
  • You must be able to stay living in your usual home for most of the season when grass pollen levels are high.
  • You must be able to follow the study protocol, which is the set of rules and steps required to participate in the trial.
  • Any preexisting stable disease is allowed, meaning any health conditions you already have must not have required a change in your medicine or a hospital visit in the 28 days before starting the study.
  • You must agree to stay in regular contact with the medical team throughout the study to ensure your safety.

Who cannot join the trial?

22 criteria

  • You cannot join if you have had any type of allergen immunotherapy (a treatment that uses small amounts of an allergen to reduce allergy symptoms) in the last 5 years.
  • You cannot participate if there is any medical reason why you should not receive subcutaneous allergen-specific immunotherapy (allergy injections given under the skin).
  • You cannot participate if you have used systemic corticosteroids (strong medicines used to reduce inflammation throughout the entire body) in the 12 weeks before joining the study.
  • You cannot participate if you previously had a serious systemic reaction (a widespread body reaction that affects more than just one area) during a skin prick test (a test where a tiny amount of an allergen is placed on the skin to check for a reaction).
  • You cannot participate if you are currently unwell, such as having an acute asthmatic exacerbation (a sudden worsening of asthma symptoms), a respiratory infection, a fever, or acute urticaria (sudden hives or itchy red bumps on the skin).
  • You cannot participate if the doctor believes any other health condition makes it too risky for you to join.
  • You cannot participate if you have chronic urticaria (long-lasting hives), severe dermographism (a condition where skin becomes raised/swollen when rubbed), severe atopic dermatitis (a chronic itchy skin condition), a sunburn, active psoriasis (a skin condition causing red, scaly patches) in areas where skin tests are done, or a history of hereditary angioedema (a genetic condition causing deep swelling under the skin).
  • You cannot participate if you have any condition that makes it unsafe to use adrenaline (a medicine used to treat severe allergic reactions), such as heart disease.
  • You cannot participate if you are taking immunosuppressive treatment (medicines that lower the body's ability to fight infection), though topical medicines (applied to the skin) are allowed.
  • You cannot participate if you have other serious diseases that could interfere with the study, such as epilepsy (a brain disorder causing seizures), kidney diseases, or other major medical issues.
  • You cannot participate if you have a confirmed or suspected immunosuppressive or immunodeficient condition (a weakened immune system).
  • You cannot participate if you are sensitive to Alternaria alternata (a type of common mold).
  • You cannot participate if you have severe psychiatric disorders (mental health conditions) that prevent you from cooperating with the study.
  • You cannot participate if you are allergic to any components of a vaccine other than the grass extract.
  • You cannot participate if you have chronic lung diseases other than asthma, such as emphysema (damage to the air sacs in the lungs) or bronchiectasis (widening of the airways in the lungs).
  • You cannot participate if you are a direct relative of the person leading the study.
  • You cannot participate if you are sensitive to mites (tiny insects) or epithelia (particles from animal skin or hair) if these are clinically relevant to your health.
  • You cannot participate if you are sensitive to other allergens that are active at the same time as grass pollen.
  • You cannot participate if you are receiving biologics (special medicines made from living organisms used to treat specific diseases).
  • You cannot participate if your asthma is uncontrolled (symptoms are not well-managed) or unstable at the time of treatment.
  • Female participants who are lactating (breastfeeding) cannot participate.
  • Female participants who are able to become pregnant must use adequate contraception (methods to prevent pregnancy) and have a negative pregnancy test before starting.
Clinical Trials Concierge

Prefer not to search? Our Concierge searches the trials for you.

Tell us about your condition – we search every trial in Europe and connect you with the right site.

We usually reply within a few days

Verified sites

All sites with verified contact details – recruitment status may not be available; ask directly

Trial locations

Where you can join this trial

Countries are shaded by recruitment status. Click a recruiting country to ask about joining there.

Recruiting
Not finding your country?

Not sure what to do next?

Joining a clinical trial can seem overwhelming. We guide you step by step, so you know exactly what to expect and how we support you through the process.

See the full process and FAQ

Investigated drugs

  • Depigoid Grass-Mix

    is an immunotherapy treatment consisting of a mixture of grass pollen extracts that have been processed to remove color. It is administered through injections under the skin to help the body build a tolerance to grass allergens.

  • Depigoid FORTE Grass-Mix

    is a more concentrated version of the grass pollen immunotherapy. Like the other version, it contains processed grass pollen extracts and is given via injections under the skin to help reduce allergic reactions to grass.

What is already known about the treatment

  • Depigoid Grass-Mix (1000 DPP/ml)

    This medication is an injectable liquid suspension administered through a needle under the skin. It contains processed extracts from various grass pollens and is used to treat allergic hay fever and related respiratory issues. By exposing the immune system to small, controlled amounts of these allergens, it helps the body learn to stop overreacting to grass pollen. This substance belongs to the class of allergen immunotherapy treatments.

  • Conjunctival Provocation Test Grass-Mix LETI 30 HEP/ml

    This product is a liquid solution used as eye drops to test for allergic reactions in the eyes. It contains extracts from common grass pollens and is utilized in medical settings to confirm if a patient is sensitive to specific allergens. The solution works by triggering a controlled local reaction when it comes into contact with the surface of the eye. It is classified as a diagnostic allergen extract for provocation testing.

  • Depigoid FORTE Grass-Mix (3000 DPP/ml)

    This medication is a high-concentration injectable suspension applied via a needle under the skin. It consists of processed grass pollen extracts designed to treat allergic rhinoconjunctivitis and asthma triggered by grass allergies. It functions by retraining the immune system to become less sensitive to pollen at a molecular level over time. This treatment is categorized as an allergen immunotherapy.

Investigated diseases

Allergic rhinoconjunctivitis with or without controlled asthma - This condition involves an allergic reaction affecting the nose and the eyes, often occurring alongside managed asthma symptoms. It is triggered when the immune system overreacts to inhaled substances like pollen. Common symptoms include sneezing, a runny or stuffy nose, and itchy, watery eyes. The condition typically worsens during specific seasons when allergen levels are high in the air. As it progresses, the inflammation in the nasal passages and airways can lead to increased sensitivity to various environmental triggers.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2025-521736-10-00Protocol code0600-PG-PSC-218Estimated enrolment324 patientsSponsorLETI Pharma S.L.U.

sourced from the EU Clinical Trials Register and site verification

Want to learn more about this trial or check if you can participate?

Clinical Trials Concierge

Prefer not to search? Our Concierge searches the trials for you.

Tell us about your condition – we search every trial in Europe and connect you with the right site.