In short
Phleum pratense pollen, depigmented polymerized extract is an investigational allergen immunotherapy substance developed by LETI Pharma, S.L.U. It is being studied in two Phase 3 clinical trials involving a total of 667 participants with allergic rhinoconjunctivitis, with or without asthma, caused by grass and olive pollen. The substance is given as a subcutaneous injection under the product names Depigoid DUO Grass-Mix/Olea, Depigoid Grass-Mix, and Depigoid FORTE Grass-Mix.
Key points
- Phase 3 trials are testing grass and olive pollen immunotherapy in allergic rhinoconjunctivitis with or without asthma.
- Two authorised trials together plan to enrol 667 participants (343 and 324 respectively).
- The treatment is a subcutaneous injection of depigmented, polymerized pollen extract.
- The main measure is a combined symptom and medication score (cSMS, 0–6) recorded during peak pollen season.
- Both trials compare active treatment against placebo after at least 8 injections.
- The substance is investigational, with no marketing authorisation in the product records.
What is Phleum pratense pollen, depigmented polymerized extract?
Phleum pratense pollen, depigmented polymerized extract is an investigational allergen immunotherapy substance. It is a chemically modified pollen extract in which the allergenic proteins have been depigmented and polymerized to reduce their ability to trigger allergic reactions while keeping their ability to train the immune system. The substance is supplied by LETI Pharma, S.L.U. and has no marketing authorisation in the product records, meaning it is still being studied in clinical trials rather than being an approved medicine.
In the trial records, the substance appears under several product names: Depigoid DUO Grass-Mix/Olea (1000 DPP/ml + 1000 DPP/ml), Depigoid Grass-Mix (1000 DPP/ml), and Depigoid FORTE Grass-Mix (3000 DPP/ml). These are fixed combinations of depigmented, polymerized extracts from several grass pollens (Phleum pratense, Festuca elatior, Dactylis glomerata, Poa pratensis, Lolium perenne) and, in the DUO product, olive pollen (Olea europaea).
How does Phleum pratense pollen, depigmented polymerized extract work?
Allergen immunotherapy works by repeatedly exposing the immune system to small, controlled amounts of the substance that causes the allergy. Over time, this can shift the immune response away from the allergic reaction and toward tolerance. The depigmentation and polymerization steps are intended to reduce the risk of immediate allergic reactions to the injection while preserving the immune-modifying effect. A published report on a related depigmented grass-birch allergoid states that the safety and efficacy of specific immunotherapy with depigmented and polymerized allergen extracts of pollen is well documented in several clinical trials.
Which conditions is it used or studied for?
- Allergic rhinoconjunctivitis due to grass and olive pollen — the GOES trial studies people with hay fever symptoms affecting the nose and eyes caused by sensitisation to grass and olive pollen, with or without asthma.
- Allergic rhinoconjunctivitis with or without controlled asthma — the GIRA trial studies people with grass pollen allergy causing nose and eye symptoms, with or without asthma that is under control.
How is Phleum pratense pollen, depigmented polymerized extract given?
The substance is formulated as a suspension for injection and is given by subcutaneous injection, meaning under the skin. The trial records list 0.5 ml as the injection volume. Two concentrations are being studied: 1000 DPP/ml and 3000 DPP/ml (the FORTE formulation).
What do the clinical trials show?
Two Phase 3 clinical trials are authorised and listed in the EU Clinical Trials Information System. Both are interventional, randomised, and placebo-controlled. The GOES trial (2025-521709-42-00) plans to enrol 343 participants and tests Depigoid DUO Grass-Mix/Olea against placebo. The GIRA trial (2025-521736-10-00) plans to enrol 324 participants and tests two strengths of Depigoid Grass-Mix (1000 DPP/ml and 3000 DPP/ml) against placebo.
The main outcome in both trials is the combined symptom and medication score (cSMS), a scale from 0 to 6 that captures both allergy symptoms (runny nose, sneezing, itchy nose, nasal congestion, itchy eyes, tearing) and the medication used to treat them (antihistamine eye drops, oral antihistamine, intranasal corticosteroid). The score is collected through a mobile app during the peak grass and olive pollen season, after at least 8 injections of treatment.
The GIRA trial also has an open-label phase that measures the change in the amount of allergen needed to produce a positive conjunctival provocation test (CPT) after the pollen season compared with baseline.
Who can take part in these trials?
The trials are open to adults and possibly adolescents with allergic rhinoconjunctivitis caused by grass pollen, or grass and olive pollen, with or without asthma. The GOES trial requires clinically relevant sensitisation to grass and olive pollen. The GIRA trial requires allergic rhinoconjunctivitis with or without controlled asthma. Detailed eligibility criteria are available in the registry records.
What side effects are known?
Specific published safety information for this exact product is not available in the provided sources. The published report on a related depigmented grass-birch allergoid states that the safety and efficacy of specific immunotherapy with depigmented and polymerized allergen extracts of pollen is well documented in several clinical trials, but does not list individual side effects.