Study to evaluate the safety and efficacy of a treatment consisting of immunotherapy by subcutaneous injection of a combination of Der p 1/Der p 2/Der p 23 allergens at different doses in patients with allergic rhinitis or rhinoconjunctivitis with or without allergic asthma.

Prior treatment

• Any total contraindication to treatment with allergen-specific immunotherapy or defined within the study according to the SmPC. In case of partial contraindication, the investigator will perform a personalized benefit/risk assessment.
• Recent or anticipated nasal or paranasal surgery (e.g., polyposis) that may interfere with the trial, at the investigator's discretion
• Severe or uncontrolled asthma according to GINA 20245 guidelines or unstable asthma (i.e., clinically relevant exacerbations in the 3 months prior to inclusion), including a baseline FEV1<80%. NOTE: clinically relevant exacerbations are defined as any worsening of asthma requiring hospitalizations or emergency department visits and necessitating systemic corticosteroid therapy for ≥ 3 consecutive days, or any exacerbation requiring initiation or increase in baseline systemic corticosteroid intake for ≥ 3 consecutive days
• Concurrent participation in another clinical trial.
• Current drug or alcohol abuse or abuse during the previous year, or any substance abuse that may interfere with the trial in the investigator's discretion.
• History of allergic reaction to any of the excipients present in the investigational product formulation.
• Use of other immunotherapy against D. pteronyssinus or other house dust mites (D. farinae) for more than one month in the last 5 years.
• Current treatment with any type of immunotherapy with other allergens during the study period.
• Current treatment or during the previous 16 weeks with any biological agent for allergic rhinoconjunctivitis and/or atopic dermatitis and/or any other non-allergic disease (dupilumab, benralizumab, mepolizumab, omalizumab, tezepelumab, among others).

Other illness

• Severe uncontrolled systemic disease that poses a risk to participants, including but not limited to autoimmune, cardiovascular or hematologic disease, hyperthyroidism, clinically relevant liver or kidney disease, malignant tumors or chronic infection, severe unstable pulmonary disease as judged by a physician.
• Active HIV infection
• Active tuberculosis.
• Dermographism, skin disease or skin disorders that interfere with the evaluation of skin tests.
• Psychiatric disorder that prevents adequate compliance with the immunotherapy program.
• Patients on current psychiatric treatment that interferes with diagnostic testing (e.g., tricyclic antidepressants). In case of needing psychiatric medication, this should not be withdrawn in order to be included in the study.
• Non-cooperative attitude or non-compliance or taking medication to control allergic rhinitis/rhinoconjunctivitis symptoms other than that provided in this study.

Other

• Moderate to severe atopic dermatitis.
• Patients/legal representatives who decline to participate or do not sign informed consent or assent.
• Pregnant or lactating women.
• Contraindication to the use of adrenaline.
• Any total contraindication for SmPC. In case of partial contraindication, the investigator will perform a personalized assessment (e.g., chronic or infectious conjunctivitis/polyposis).
• Patients sensitized to epithelials (e.g. cat, dog, horse, mouse) who live with these animals or have frequent contact with them (direct or indirect)
• Patients with clinically relevant sensitization to storage mites (mainly Lepidoglyphus destructor or Blomia tropicalis) at the investigator's discretion.
• Patients with clinically relevant sensitization to fungi (mainly Alternaria alternata) at the investigator's discretion.

• Patients/legal representatives who have understood and signed the informed consent or assent form.
• Patients between 12 and 65 years of age, both inclusive.
• Patients with moderate or severe persistent allergic rhinitis and/or rhinoconjunctivitis (according to ARIA2 guidelines) for at least the last year, caused by clinically relevant sensitization to Dermatophagoides genus, fulfilling all the criteria described below: 3.a. Clinical history with symptoms compatible with demonstrated hypersensitivity to the genus Dermatophagoides. 3.b. Positive skin prick test (papule of ≥3 mm with respect to the negative control) against at least one of the following major allergens: Der p 1, Der p 2 or Der p 23 performed at most 12 months prior to inclusion. 3.c. Specific IgE ≥0.7 kU/L against at least one of the following major allergens: Der p 1, Der p 2 or Der p 23. performed at most 12 months prior to the inclusion visit. 3.d. Positive CFP to the mixture extract of the purified allergens Der p 1/Der p 2/Der p 23.
• Asthmatic patients with a forced expiratory volume in the first second (FEV1) ≥ 80%.
• Women of childbearing age should have a negative urine pregnancy test (childbearing is defined as from menarche to postmenopause, unless sterilized by hysterectomy, bilateral salpingectomy, and bilateral oophorectomy) and be willing to use an effective method of contraception from 14 days before the first administration until 30 days after the last administration of the investigational drug.
• Patients willing to comply with all study procedures, and have availability for follow-up for the duration of the study.