Recombinant Human C1 Inhibitor for the Treatment of Early Antibody-Mediated Rejection in Renal Transplantation

Inclusion Criteria: * Recipients of renal transplantation within 30 days prior to enrollment. * AMR documented by light microscopic changes and immunohistochemical C4d staining on renal biopsy within 30 days post-transplant. * Positive DSA as detected by magnetic microbeads using a Luminex® system. * Age ≥ 18 years. * Women of child-bearing potential (CBP) must have negative pregnancy test at screening. * Women of CBP and men with sexual partners of CBP must agree to use a medically acceptable method of contraception throughout the study and for 3 months following discontinuation of assigned treatment. * Subjects must be capable of understanding the purpose and risks of the study and must sign a statement of informed consent. Exclusion Criteria: * Recipients of multi-organ transplants. * Recipients with previous early AMR. * Recipients with a known hypersensitivity to C1INH, rabbit anti-thymocyte globulin, or any rabbit protein. * History of malignancy within 3 years of enrollment (except for adequately treated basal cell or squamous cell carcinoma of the skin). * Subjects who are positive for hepatitis C, hepatitis B surface antigen, or HIV at the time of transplant. * Subjects who are actively taking an investigational drug. * Subjects with a history of a psychological illness or condition that could interfere with the subject's ability to understand the requirements of the study. * Female subjects who are pregnant or nursing. * Subjects with hemodynamic instability, as defined by a mean arterial pressure (MAP) \<60 mmHg or \>110 mmHg; or requirement of vasopressors to maintain a MAP of 60 mmHg; or requirement of IV vasodilators for hypertensive emergency; or acute pulmonary edema. * Subjects with known active infection at the time of enrollment. * Biopsy-confirmed concurrent cellular rejection requiring polyclonal antibody therapy (i.e., all Grades other than Banff 1a and 1b will be excluded).