A Study to Evaluate Efficacy and Safety of Abatacept in Participants of Pemphigus Vulgaris (PV)

Inclusion criteria

• ✓. Adults (18 through 80 years of age) with clinically-documented diagnosis of PV for \>2 months and \<10 years.
• ✓. History of biopsy consistent with PV (Hematoxylin and Eosin staining and direct immunofluorescence). Confirmed diagnosis of PV within the previous 24 months, based on the presence of histological features of acantholysis via skin or mucosal biopsy and one of the following: tissue bound immunoglobulin G (IgG) antibodies by direct immunofluorescence on the surface of affected epithelium or serological detection of serum desmoglein-3 (DSg3) autoantibodies against epithelial cell surface either by indirect immunofluorescence microscopy or by enzyme-linked immunosorbent assay.
• ✓. At least 1 previous episode of a failed steroid taper (ie, disease flare/relapse) at a prednisone/prednisolone dose \>10 mg/day. The following criteria must have been met as evidence of disease severity at the time of the failed steroid taper: a) A Pemphigus Severity of Clinical Disease score of moderate (2) or severe (3) (may be historical/retrospective assessment). b) Required a treatment change at the time of the failed steroid taper of at least one of the following: i) A steroid increase to \>=20 mg/day OR ii) The addition of immunosuppressive/immunomodulatory agent/treatment OR iii) A dose increase of immunosuppressive/immunomodulatory agent/treatment
• ✓. Screening anti-Dsg antibodies consistent with a diagnosis of PV (ie, elevated antiDsg3 antibodies).
• ✓. Has initiated and received a stable dose of prednisone/prednisolone from a minimum of 20 mg/day (example: 0.25 mg/kg/day for an 80 kg person) up to a maximum of 120 mg/day or 1.5 mg/kg/day (whichever is higher) for \>=2 weeks prior to randomization.
• ✓. Has exhibited PV disease control, defined as no new lesions for \>=2 weeks. A female subject is eligible to enter the study if she: Is of non-child bearing potential, who 7. is either surgically sterile (bilateral tubal ligation, bilateral oophorectomy, or post-hysterectomy) or is postmenopausal without menses for \>2 years. Women who are \<2 years postmenopausal are required to have menopausal status confirmed by follicle-stimulating hormone (FSH) and estradiol levels at the screening evaluation. If FSH and estradiol levels do not provide confirmation of menopause, subject will be considered to be of childbearing potential.