REscue of Nephrons With ALe.F02 (RENAL-F02) (RENAL-F02)

Inclusion Criteria: Are male or female patients ≥18 years of age of any race or ethnicity with a score of <7 on the Clinical Frailty Scale in the 3 months preceding the onset of RPGN attributed to AAV; Note: The PI should assess the Clinical Frailty Scale based on medical history and interview with the patient Must be willing and able to comply with the study requirements and give informed consent for participation in the study; Must be willing to have a renal biopsy procedure performed no later than prior to study drug administration at the Week 6 Visit; Have been newly diagnosed with RPGN within 30 days prior to the initiation of study drug treatment, as demonstrated by the following: - Evidence of loss of renal function with an eGFR of ≤50 mL/min/1.73 m2 and ≥15 mL/min/1.73 m2; and - History of proteinuria of any degree AND/OR hematuria that is temporally associated with the presenting episode of illness and supports the diagnosis of RPGN. Note: The hematuria may be represented by the presence of eumorphic or dysmorphic red blood cells (RBCs) and/or RBC casts. Are suspected of having RPGN attributed to AAV at Screening based on clinical laboratory diagnostic criteria, including a positive test for an ANCA, ie, anti-myeloperoxidase (MPO) or anti-proteinase 3 (PR3); Female patients must not be pregnant or lactating at Screening and 1 of the following conditions must apply: - Is a female of childbearing potential and agrees to use a highly effective method of birth control during their participation in the study and for at least 5 half-lives or a minimum of 30 days after the last dose of study drug, or as recommended in the Summary of Product Characteristics (SmPC) of any authorized AxMP given as part of background standard of care (SOC) therapy, whichever is longer; or - Is a female of nonchildbearing potential. Female patients must agree not to donate ova for 6 months after the last dose of study drug or as recommended in the SmPC of any authorized AxMP given as part of background SOC therapy, whichever is longer; Male patients must agree to use contraception, in the form of either sexual abstinence or a condom, during their participation in the study and for 90 days after the last dose of study drug or as recommended in the SmPC of any authorized auxiliary medicinal product (AxMP) given as part of background SOC therapy, whichever is longer; and Male patients must agree to abstain from sperm donation during their participation in the study and for 90 days after the last dose of study drug or as recommended in the SmPC of any authorized AxMP given as part of background SOC therapy, whichever is longer. Exclusion Criteria: Have a history of previous RPGN that resolved or ameliorated (ie, the patient had a documented case of RPGN and has suffered a relapse); Have a positive serology test for anti-glomerular basement membrane antibodies; Have evidence of active or latent tuberculosis (TB) determined by a positive (not indeterminate) QuantiFERON®-TB Gold test (or equivalent). Radiological criteria, including chest X-ray or computed tomography scan, must not be used to exclude TB; Have a chronic infection that could be exacerbated by RPGN or SOC therapy for RPGN; Have active hepatitis B, hepatitis C, or HIV infection; Have taken any prohibited medications, including >3000 mg of IV methylprednisolone equipotent glucocorticoids, or >40 mg/day oral glucocorticoids (prednisone equivalent) for >14 days, as part of acute RPGN care within 14 days prior to Screening; Have been treated or planned to be treated with protocol prohibited medications. Have poor venous access; Have participated in an investigational drug or device study and received investigational therapy <30 days or 5 half lives, whichever is the greater, prior to the first dose of study drug. For biological investigational drugs, the exclusionary period may not be <90 days prior to the first dose of study drug; Have a history of psoriasis, AD, excessively dry skin or recurrent conjunctivitis that has required treatment prescribed by a physician, scleroderma, vitiligo, or any other active autoimmune dermatological disorder, with the exception of dermatological disorders or skin rashes that are attributable to, or known to be associated with, the underlying diagnosis of AAV, which shall not be exclusionary; Have a diagnosis of systemic lupus erythematosus-AAV overlap syndrome; Have a diagnosis of eosinophilic granulomatosis with polyangiitis; Have evidence of uncontrolled respiratory, cardiac, hepatic, endocrine, central nervous system, or renal disease, unrelated to RPGN or AAV, that the PI believes cannot be readily brought under control, or any other medical condition that in the opinion of the PI renders the patient unsuitable for enrollment and could prevent the successful completion of the study; Have received a live vaccine within 30 days prior to Screening; Have received any vaccine within 7 days of the first dose of study drug other than against influenza or pneumococcal infection; Are employed by the PI or the study site, have direct involvement in the proposed study or other studies under the direction of that PI, or are a family member of the PI or study site personnel; Have not recovered from AEs and/or complications from major surgery prior to the first dose of study drug; Note: The PI should consult with the Medical Monitor and Sponsor to determine if ongoing, significant complications from major surgery are exclusionary. Have active or known history of alcohol or substance abuse within 1 year prior to Day 1/Randomization or have a positive urine drug screen for drugs of abuse at Screening; Have been diagnosed within the preceding 5 years with a malignant neoplastic disease, other than locally invasive cutaneous squamous or basal cell carcinoma; Have alveolar haemorrhage with hypoxia defined by an oxygen saturation <85% or that requires the use of invasive or noninvasive ventilatory support; Have undergone dialysis within 14 days prior to Screening; Have undergone therapeutic plasma exchange within 14 days prior to the first dose of study drug; or Have known hypersensitivity to the study drug or any of the excipients used in the formulation of the study drug.