Study in Adult Asthmatic Patients With Allergic Bronchopulmonary Aspergillosis

Inclusion Criteria:

* Is a male or female, 18 to 75 years old (inclusive) at the time of signing the informed consent.
* Has a body mass index of 18.0 to 35.0 kg/m2 (inclusive) at screening.
* Has a historical diagnosis of asthma, as per the Global Initiative for Asthma (GINA) 2018 update.
* Has a confirmed historical diagnosis of ABPA, as per the Modified International Society for Human and Animal Mycology (ISHAM) working group 2013 criteria.
* Is currently considered to be in one of the following stages of ABPA: Stage 2 (Response), Stage 4 (Remission), Stage 5a (Treatment-dependent ABPA), or Stage 5b (Glucocorticoid-dependent asthma)
* Has a serum immunoglobulin (Ig) E ≥1000 IU/mL during screening (Visit 1 or Visit 2).
* Can perform a valid, reproducible spirometry test with demonstration of a prebronchodilator FEV1 ≥50% of predicted normal for age, sex, race, and height (Quanjer et al 2012) at a screening visit.
* Has a documented stable asthma medication regimen during screening (Day 28 to Day 1), including SABA, LABA, and LTRA use and inhaled and/or oral GCS.
* Subjects who are sexually active, male subjects able to father a child, and female subjects of childbearing potential must agree to follow the contraception requirements of this protocol.
* Can demonstrate the correct inhalation technique for the use of the delivery device at screening and before dosing.

Exclusion Criteria:

* Is a female of childbearing potential who is pregnant or lactating or who plans to become pregnant during the study. A woman is considered to be of childbearing potential unless she is either permanently sterile (hysterectomy, bilateral salpingectomy, bilateral oophorectomy, bilateral tubal occlusion/ligation) or postmenopausal (had no menses for 12 months without an alternative medical cause).
* Has a history of life-threatening asthma within the last 5 years, defined as an asthma episode that required intubation and/or was associated with hypercapnia, respiratory arrest, and/or hypoxic seizures.
* Had an occurrence of asthma or ABPA exacerbations within the 28 days before screening or during the 28-day period before Day 1.
* Had an occurrence of clinically significant bacterial, viral, or fungal infection that required systemic (oral or intravenous) antibiotics, antivirals, or antifungals within the 28 days before screening. Topical treatments, other than antifungals, are allowed.
* Received any investigational medical product in a clinical research study within the previous 3 months before dosing in this study.
* Has previously received PUR1900.
* Has a history of any significant drug or alcohol abuse in the past 2 years before screening, as judged by the investigator.
* Has current tobacco or inhaled marijuana use or history of smoking tobacco or marijuana within the last 6 months before screening.
* Is a current user of e-cigarettes or has used these products within the last 6 months before screening.
* Has a positive urine test result for drugs of abuse, alcohol, or cotinine at screening
* Has a history of allergies to or hypersensitivity reactions after dosing of itraconazole or other antifungal azoles.
* Had a major trauma or surgery within the last 28 days before screening.