In short
Phleum pratense pollen enriched allergoid, mannan-conjugated, polymerised is an investigational immunotherapy derived from grass pollen. It is being studied in one authorised Phase 4 trial with 450 planned participants who have grass pollen-induced allergic rhinitis or rhinoconjunctivitis. The trial compares two subcutaneous concentrations to find the one with the best efficacy and safety profile.
Key points
- Phase 4 dose-finding trial in grass pollen-induced allergic rhinitis or rhinoconjunctivitis
- 450 participants planned in a randomised, double-blind, placebo-controlled design
- Given as a subcutaneous injection in two concentrations (3000 mTU/mL and 9000 mTU/mL)
- Primary outcome is the Combined Symptom and Medication Score (CSMS) during the 2027 grass pollen season
- Trial status: Authorised, not yet recruiting
- Substance is also authorised in Germany as skin-prick test solutions for allergy diagnosis
What is Phleum pratense pollen allergoid?
Phleum pratense pollen enriched allergoid, mannan-conjugated, polymerised is a modified grass pollen extract used in allergy immunotherapy. It belongs to the therapeutic area of immune system diseases and is classified under ATC code V01AA02 Grass pollen. The substance is described in registry records as a structurally diverse substance of herbal origin. It appears in product records under names including HAL Allergy Prick Test Wiesenlieschgras, Mannan-conjugated allergoid (polymerized) Phleum pratense and Dactylis glomerata parenteral vaccine, and HAL Allergy Prick Test Gräserpollen-Mischung. The substance is already authorised as a medicine in Germany for skin-prick testing, under authorisation records DE 753A/89N and DE 760A/89N, held by HAL Allergy B.V. and Inmunotek S.L. In the clinical trial described here, the substance is the investigational medicinal product being tested.
How does Phleum pratense pollen allergoid work?
The substance is an allergoid, meaning the grass pollen proteins have been chemically modified and polymerised, then conjugated to mannan. This modification is intended to reduce the allergenicity of the pollen proteins while retaining their ability to train the immune system. The trial record states that the product is a mannan-conjugated allergoid administered subcutaneously to patients with grass pollen-induced allergic rhinitis or rhinoconjunctivitis. The aim of this immunotherapy approach is to shift the immune response away from the allergic reaction that causes symptoms during the grass pollen season. The registry data do not provide further detail on the molecular mechanism.
Which conditions is it used or studied for?
- Grass pollen-induced allergic rhinitis or rhinoconjunctivitis — the condition studied in the Phase 4 trial, involving nasal and eye symptoms triggered by grass pollen.
In addition to the investigational use, the substance is authorised as skin-prick test solutions for diagnosing grass pollen allergy in Germany.
How is Phleum pratense pollen allergoid given?
The investigational product is given as a subcutaneous injection. The trial tests two concentrations, 3000 mTU/mL and 9000 mTU/mL, administered subcutaneously. The pharmaceutical forms recorded for this substance are solution for injection and solution for skin-prick test, with routes of administration being subcutaneous and subcutaneous injection. The skin-prick test solutions are used for allergy diagnosis rather than treatment.
What do the clinical trials show?
One trial is registered for this substance in the EU Clinical Trials Information System. It is a Phase 4, prospective, randomised, double-blind, placebo-controlled, multicentre, dose-finding trial. The trial plans to enrol 450 participants with grass pollen-induced allergic rhinitis or rhinoconjunctivitis. The primary objective is to assess the clinical efficacy of two concentrations, 3000 mTU/mL and 9000 mTU/mL, to determine which concentration offers the best efficacy while taking safety and tolerability into account.
The primary outcome measure is the mean daily Combined Symptom and Medication Score (CSMS), as defined in the EAACI position paper by Pfaar et al., 2014, measured over the peak grass pollen season in 2027. The trial status is Authorised, meaning it has received regulatory approval but is not yet recruiting participants. The trial also includes a placebo arm and several rescue medications, including nasal sprays, antihistamine tablets and eye drops, which are provided as standard care during the study.
The trial design is double-blind, meaning neither participants nor investigators know which treatment each participant receives. The comparison is between the two concentrations of the allergoid and placebo. The study also uses skin-prick tests with various allergens, including grass pollen, cat epithelium, dog epithelium, house dust mite and Alternaria alternata, to characterise participants' allergic profiles.
What side effects are known?
The registry data provided do not include information on side effects for this investigational product. The trial record states that safety and tolerability will be assessed as part of the dose-finding objective, but no specific adverse event data are available in the sources provided.