Biological Potency of the Cat Epithelial Allergenic Extracts

This is an open-label, non-randomized phase II clinical trial.

Three different concentrations of three different cat epithelial allergenic extracts, together with a positive and negative control, using 10 mg/ml histamine dihydrochloride and a glycerated phenol saline solution, respectively, will be tested in every subject on the volar surface of the forearm.

• 1 (Dose Response Skin Prick Tests) (Biological): 3 different cat epithelium allergenic extracts at 3 different concentrations, together with a positive and negative control will be tested in every patient in duplicate on the volar surface of the forearm.

Primary outcomes

• Wheal size area (mm2)elicited on the skin after the dose-response prick-test [Test sites should be inspected and recorded 15-20 min after application]: Wheal size area (mm2)elicited on the skin after the dose-response prick-test, in duplicate, of the native and depigmented polymerized cat epithelial allergenic extracts, together with the area of the wheals induced by the positive and negative controls.

Secondary outcomes

• Wheal size area (mm2)elicited on the skin after the dose-response prick-test [Test sites should be inspected and recorded 15-20 min after application]: Wheal size area (mm2)elicited on the skin after the dose-response prick-test, in duplicate, of the native and depigmented cat epithelial allergenic extracts, together with the area of the wheals induced by the positive and negative controls.
• Wheal siza area (mm2)elicited on the skin after the dose-response prick-test [Test sites should be inspected and recorded 15-20 min after application]: Wheal siza area (mm2)elicited on the skin after the dose-response prick-test, in duplicate, of the depigmented and depigmented polymerized cat epithelial allergenic extracts, together with the area of the wheals induced by the positive and negative controls.
• Determine the HEP dose of the native (N) cat epithelial allergenic extract [Wheals will be elicited in visit 2. CRFs will be retrieved, measured in-house and filed back in the site before study closure (maximum 3 months after being elicited).]: Calculation will be made of the 10 HEP dose of the native (N) cat epithelial allergenic extract.
• Loss of in vitro potency of the cat epithelial allergenic extracts [Blood will be collected in visit 2. Serum samples will be analyze once every sample is received. The samples will be analyzed at most 12 months after received]: To quantify the loss of in vitro potency of cat epithelial allergenic extracts, based on specific IgE and IgG inhibition studies.

Sex: All, ages: 18 Years to 60 Years

Inclusion Criteria:

A subject will be eligible for inclusion in the study only if all of the following criteria are met:

* The subject (and/or legal representative, where applicable) has given written, signed and dated informed consent.
* Subjects of either sex and of any race or ethnic group.
* Age > 18 years and < 60 years on the day of inclusion in the study.
* Positive clinical history of allergy to cat epithelia (i.e., rhinitis, conjunctivitis, rhinoconjunctivitis, asthma, urticaria, etc. ).
* A positive prick-test (mean diameter of papule ≥ 3 mm or area of papule ≥ 7 mm2) with a commercial extract of cat epithelium. The results of the prick-test will be valid if they were obtained in the year prior to inclusion of the subject in the study.
* A positive specific IgE test (> 0.70 KU/l) for cat epithelium. The results of the IgE test will be valid if they were obtained in the year prior to inclusion of the subject in the study.

Exclusion Criteria:

A subject will NOT be eligible for inclusion in the study if any of the following criteria are met:

* Immunotherapy in the last 5 years involving allergens known to be able to interfere with the test allergen (e.g., cat extract).
* Use of drugs that can interfere with the skin response before and during the study (e.g., antihistamines), within the intervals established in section 9.1 and appendix 1.
* Treatment with any of the following medicines: tricyclic or tetracyclic antidepressants or MAOIs (Monoamine oxidase inhibitors), beta-blockers or chronic use of oral corticosteroids or use of corticosteroids via either the oral or the parenteral route in repeated and intermittent dosing regimens (> 10 mg/day of prednisone or equivalent).
* Pregnant or nursing women and women with a positive pregnancy test in visit 2.
* Dermographism affecting the skin of the test site, in either of the two visits to the study centre.
* Atopic dermatitis affecting the skin of the test site, in either of the two visits to the study centre.
* Urticaria affecting the skin of the test site, in either of the two visits to the study centre.
* Clinically relevant immune system diseases (both autoimmune disorders and immune deficiencies). (Hashimoto's thyroiditis with hypothyroidism well controlled through thyroid hormone therapy does not necessarily represent a contraindication. Graves' disease (hyperthyroidism) would be an exclusion criterion due to the potential risk in the event adrenaline must be used.)
* Serious uncontrolled diseases that may increase the safety risk of the subjects participating in the study, including but not limited to the following: heart failure, serious or uncontrolled respiratory diseases, endocrine disorders, clinically relevant liver or kidney diseases, or haematological disorders.
* Patents with diseases or conditions that limit adrenaline use (coronary disease, severe arterial hypertension, etc.).
* Serious psychiatric, psychological or neurological problems.
* Medication, alcohol or illegal drug abuse in the last year.
* Participation in any other clinical trial during the 30 days (or 5 times the biological half-life of the investigational product - whichever is longest) prior to inclusion of the subject in this study.

• Lena M Erbiti, Study chair, Laboratorios LETI, S.L.Unipersonal