A Study to Evaluate the Safety and Tolerability of Efgartigimod PH20 SC Given by Prefilled Syringe in Kidney Transplant Recipients With Antibody-Mediated Rejection (AMR)

Inclusion Criteria: * The participant is within the ages of 18 and 80 years old * The participant had a kidney transplant (living or deceased donor) at least 6 months before the study * The participant has received a diagnosis of active or chronic active antibody-mediated rejection (AMR) with detectable donor-specific antibodies at time of the study * A participant may be allowed into the study if they receive the following medications: 1. Received mycophenolate mofetil for at least 20 weeks before the study 2. Has remained on a stable dose of mycophenolate mofetil and tacrolimus for at least 4 weeks before being allowed to participate in the study 3. Has remained on tacrolimus doses between 5 to 10 ng/mL at least 4 weeks before being allowed to participate in the study 4. Steroid dose was between 0 to 10 mg per day of prednisone (or dose equivalent) for at least 4 weeks before being allowed to participate in the study Exclusion Criteria: * Confirmed T-cell or mixed rejection at time of the study * Recent change in immunosuppressive therapy agents * Any other medical condition that, in the investigator's opinion, would interfere with the results of the study or put the participant at undue risk * Pregnant or lactating state or intention to become pregnant during the study The complete list of criteria can be found in the protocol