In vivo Biological Standardization of Dermatophagoides pteronyssinus and Dermatophagoides farinae Extracts in Sensitized Patients with IgE‑mediated Respiratory Allergy

The primary objective is the in vivo biological standardization of Dermatophagoides pteronyssinus and Dermatophagoides farinae allergenic extracts by determining the concentration that produces a skin test wheal of equivalent size to that elicited by a 10 mg/ml histamine dihydrochloride solution. This evaluation establishes a dose‑response relationship for the extracts, facilitating reliable diagnostic interpretation and ensuring safety parameters are met for patients with IgE‑mediated respiratory allergic disease due to these house‑dust mite allergens.

The trial enrolled adult patients with IgE-mediated respiratory allergic disease caused by the specific allergen extract under investigation; both female and male subjects aged 18 to 60 years were eligible. Participants were required to have a documented clinical history of respiratory allergy (rhinitis and/or rhinoconjunctivitis with or without asthma), a positive skin prick test (papule diameter ≥ 3 mm) using a commercially standardized extract, and a serum-specific IgE level of class 3 or higher. Additional inclusion criteria stipulated residence in a geographic region where the allergy is prevalent and provision of written informed consent. The sponsor did not provide information on the total number of participants recruited for the study.

The study is a phase 4, single‑arm, open‑label investigation aimed at the in vivo biological standardization of Dermatophagoides pteronyssinus (DPT) and Dermatophagoides farinae (DF) allergenic extracts in adults with IgE‑mediated respiratory allergic disease. After an initial screening visit to verify eligibility criteria (clinical history of respiratory allergy, positive skin prick test ≥ 3 mm, serum specific IgE ≥ class 3, age 18‑60 years, and residence in a relevant geographic area), participants undergo a series of intra‑epidermal skin prick test visits. During each test visit, a series of DPT and DF solutions at concentrations of 0.01, 0.1, 1, and 10 mg/ml are applied, together with a 10 mg/ml histamine dihydrochloride control, to determine the concentration that produces a wheal size equivalent to the histamine reference. Follow‑up assessments are performed to monitor local reactions and any adverse events. The trial concludes with an end‑of‑study visit in which final data on the primary endpoint—determination of the biological activity of the extracts—and the secondary endpoint—correlation with in vitro standardization—are collected. Participant involvement spans from the screening appointment through the final assessment, with a total study duration estimated from 15 June 2026 to 30 November 2026. Early termination may occur if a participant withdraws consent, experiences a serious adverse reaction, or fails to meet continuing eligibility criteria.

The trial utilizes a series of standardized allergen extracts of Dermatophagoides pteronyssinus prepared as sterile aqueous solution. Each concentration (0.01 mg/ml, 0.1 mg/ml, 1 mg/ml, and 10 mg/ml) is administered by a single intraepidermal injection at the designated test site during the skin testing session.

The 0.01 mg/ml extract of Dermatophagoides pteronyssinus is supplied in a vial containing a clear solution for intraepidermal use. A volume of 0.02 ml is injected into the epidermis, providing the lowest test concentration for dose‑response assessment.

The 0.1 mg/ml extract of Dermatophagoides pteronyssinus is provided as a sterile solution for intraepidermal use. A single 0.02 ml injection is performed, representing the intermediate low concentration.

The 1 mg/ml extract of Dermatophagoides pteronyssinus is presented as a sterile solution for intraepidermal use. One 0.02 ml intraepidermal injection delivers the intermediate concentration.

The 10 mg/ml extract of Dermatophagoides pteronyssinus is supplied as a sterile solution for intraepidermal use. A single 0.02 ml injection provides the highest concentration tested.

The trial also includes standardized extracts of Dermatophagoides farinae formulated as sterile aqueous solutions for intraepidermal use at concentrations of 0.01 mg/ml, 0.1 mg/ml, 1 mg/ml, and 10 mg/ml. Each concentration is administered by a single 0.02 ml intraepidermal injection during the test session.

The 0.01 mg/ml extract of Dermatophagoides farinae is provided as a solution for intraepidermal use. One 0.02 ml injection delivers the lowest test concentration.

The 0.1 mg/ml extract of Dermatophagoides farinae is supplied as a solution for intraepidermal use. A single 0.02 ml injection is administered.

The 1 mg/ml extract of Dermatophagoides farinae is presented as a solution for intraepidermal use. One 0.02 ml intraepidermal injection provides the intermediate concentration.

The 10 mg/ml extract of Dermatophagoides farinae is provided as a solution for intraepidermal use. A single 0.02 ml injection delivers the highest concentration evaluated.

As a comparator, a 10 mg/ml solution of histamine dihydrochloride is administered intraepidermally in a 0.02 ml injection. The histamine control establishes the reference wheal size for standardization of the allergenic extracts.

All administrations are performed by trained personnel following a predefined schedule. Wheal diameters are measured at 15 minutes post‑injection, and data are recorded in the case report form to monitor compliance with the dosing protocol.

Efficacy assessment is based on the in vivo determination of the biological activity of the Dermatophagoides pteronyssinus (DPT) and Dermatophagoides farinae (DF) extracts. The primary efficacy parameter is the concentration of each extract that elicits a wheal of equivalent size to that produced by a 10 mg/ml solution of histamine dihydrochloride following intra‑epidermal administration. Wheal dimensions are measured in millimetres using a calibrated ruler or planimeter immediately after test application.

Secondary efficacy evaluation includes in vitro biological standardization of the DPT and DF extracts, performed according to the laboratory methods specified in the protocol. Results from both in vivo and in vitro assessments are compared to predefined criteria to confirm standardization of allergenic activity.