• Willing and able to provide written informed consent

• Males or females ≥18 years of age

• Established diagnosis of CPA according to ESCMID/ERS criteria (2016) which includes all the following, which should be present for ≥3 months:

‣ one or more clinical symptoms (persistent cough, recurrent haemoptysis, weight loss, malaise, night sweats, fever and dyspnoea)

⁃ slowly progressive or persistent radiological findings (one or more cavities and surrounding fibrosis, infiltrates, consolidation, with or without fungal ball or progressive pleural thickening) on computed tomography (CT) of the thorax

⁃ immunological, microbiological or molecular evidence of Aspergillus infection (growth of Aspergillus in respiratory secretions or serum galactomannan index \>0.5 or BALF galactomannan index \>1), positive Aspergillus IgG, or positive PCR

⁃ exclusion of active tuberculosis or non-tuberculous mycobacterial pulmonary infection or disorders that will prevent evaluation of outcome over 6 months. Patients on anti-mycobacterial therapy can be enrolled if their mycobacterial infection is stabilised

• Unable to receive systemic azole antifungal therapy due to any of the following: documented or anticipated resistance, intolerance, contraindication (e.g. due to drug-drug interactions or organ dysfunction), inability to take oral medication, or lack of availability. NOTE: the administration of rezafungin is monotherapy only, and subjects currently on azoles who are able to remain on therapy are not eligible

• Antifungal treatment is indicated according to the opinion of the investigator due to radiological changes consistent with CPA progression OR high burden of symptoms

• Female subjects of child-bearing potential \<2 years post-menopausal (unless surgically sterile) must agree to and comply with using one barrier method (e.g., female condom with spermicide) plus one other highly effective method of birth control (e.g., oral contraceptive, implant, injectable, indwelling intrauterine device, vasectomized partner), or sexual abstinence (only possible if it corresponds to the subject's usual lifestyle) while participating in this study, and for 30 days after the last dose of study drug. Male subjects must be vasectomized, abstain from heterosexual intercourse, or agree to use barrier contraception (condom with spermicide), and agree not to donate sperm while participating in the study and for 120 days from the last IV dose of study drug, unless the partner is \>2 years post-menopausal or otherwise sterile.

‣ Definitions: Woman of childbearing potential: fertile, following menarche and until becoming post-menopausal unless permanently sterile. Permanent sterilization methods include hysterectomy, bilateral salpingectomy, and bilateral oophorectomy.

⁃ A postmenopausal state: no menses for 12 months without an alternative medical cause.

⁃ Abstinence: refraining from heterosexual intercourse (only if it corresponds to the subject's usual lifestyle)

• Willingness to comply with all aspects and assessments required in this study