A Pilot Study to Evaluate the Use of C1 Esterase Inhibitor (Human) in Patients With Acute Antibody-Mediated Rejection

The protocol-specified Day 20 (post-treatment) biopsy was compared to the qualifying biopsy to assess changes in histopathology for light and immunofluorescence microscopy. The Central Pathologist provided the following categorical information from the qualifying biopsy in an AMR Scorecard: C4d Score (0-100), Margination Score (0-100) Glomerulitis Score (0-100), Vasculitis Score (0-100), Glomerulosclerosis Score (0-100), Chronic Glomerulopathy Score (0-100), Interstitial Fibrosis Score (0-100), and the Chronic Vasculitis Score (0-100), with 0 being absence of abnormal histopathology. The "qualifying" renal allograft biopsy was performed as standard of care (SOC) within 12 months after transplant and prior to screening for this study. The first dose of study drug (Day 1) was administered within 72 hours after qualifying biopsy. A negative change from baseline indicates that histopathology has improved. Endpoint includes subjects with both Qualifying and Day 20 Biopsies.

The "qualifying" renal allograft biopsy was performed as standard of care within 12 months after transplant and prior to screening. The qualifying biopsy was used to establish the diagnosis of AMR and was evaluated for all of the following to obtain baseline assessments: the presence of C4d, and monocyte or neutrophil infiltration around the peritubular capillaries (PTCs) and/or glomeruli. The Central Pathologist provided the following information from the qualifying biopsy in an AMR Scorecard: C4d Score, Glomerulitis Score, Vasculitis Score, Glomerulosclerosis Score, Chronic Glomerulopathy Score, Interstitial Fibrosis Score, and the Chronic Vasculitis Score. The Banff AMR Scoring System was used to summarize these scores. Resolution determination was made based on clinical criteria (improvement of serum creatinine ± decrease of DSA titer, and/or increase in urine output) and histopathology. The first dose of study drug (Day 1) was administered within 72 hours after qualifying biopsy.

Graft function was assessed by measuring serum creatinine. Serum creatinine level was obtained directly from laboratory results. Baseline was the last value collected prior to first dose of study drug. A negative change from baseline indicates that serum creatinine levels have decreased. Values for Day 90 were collected +/= 14 days.

Graft function was assessed by measuring creatinine clearance. Creatinine clearance was calculated by the Cockcroft-Gault formula. Baseline was the last value collected prior to first dose of study drug. A positive change from baseline indicates that the clearance rate has increased. Values for Day 90 were collected +/= 14 days.

If necessary, rescue therapy included plasmapheresis. Participating centers used plasmapheresis for desensitization, if necessary, prior to transplant and also for the treatment of acute AMR. Plasmapheresis therapy was performed for the qualifying episode of AMR according to standards at the investigational site and at the discretion of the investigator. Sessions include those prior to first dose. If plasmapheresis therapy occurred on the same day as study drug dosing, study drug was administered after completion of the plasmapheresis session.

If necessary, rescue therapy included splenectomy.

Allograft failure was determined by the presence of the following criteria: current renal allograft nephrectomy and/or a clinical determination that the allograft irreversibly and irrevocably ceased functioning.

Plasma samples were used for the determination of antigenic C1 INH concentrations. Primary pharmacokinetic (PK) parameters were calculated using baseline-corrected concentration-versus-time data following the last dose and noncompartmental techniques, as appropriate. The following PK parameters were calculated: baseline concentration (Cbaseline), maximum concentration (Cmax), average concentration at steady-state (Cav,ss), time to maximum concentration (tmax), minimum concentration (Cmin), area under the concentration-time curve from time zero to last quantifiable concentration at time t (AUC0-t). Blood was collected on Day 13 at the indicated timepoints. If plasmapheresis was performed on a dosing day, blood samples were obtained before plasmapheresis, prior to study drug administration (post-plasmapheresis), and at time points relative to the start of infusion.

Plasma samples were used for the determination of functional C1 INH concentrations. Primary pharmacokinetic (PK) parameters were calculated using baseline-corrected concentration-versus-time data following the last dose and noncompartmental techniques, as appropriate. The following PK parameters were calculated: baseline concentration (Cbaseline), maximum concentration (Cmax), average concentration at steady-state (Cav,ss), time to maximum concentration (tmax), minimum concentration (Cmin), area under the concentration-time curve from time zero to last quantifiable concentration at time t (AUC0-t). Blood was collected on Day 13 at the indicated timepoints. If plasmapheresis was performed on a dosing day, blood samples were obtained before plasmapheresis, prior to study drug administration (post-plasmapheresis), and at time points relative to the start of infusion.

Plasma samples were used for the determination of antigenic and functional C1 INH concentrations. Primary pharmacokinetic (PK) parameters were calculated using baseline-corrected concentration-versus-time data following the last dose and noncompartmental techniques, as appropriate. The following PK parameters were calculated: baseline concentration (Cbaseline), maximum concentration (Cmax), average concentration at steady-state (Cav,ss), time to maximum concentration (tmax), minimum concentration (Cmin), area under the concentration-time curve from time zero to last quantifiable concentration at time t (AUC0-t). Blood was collected on Day 13 at the indicated timepoints. If plasmapheresis was performed on a dosing day, blood samples were obtained before plasmapheresis, prior to study drug administration (post-plasmapheresis), and at time points relative to the start of infusion.

Plasma samples were used for the determination of antigenic C1 INH parameters. Primary pharmacokinetic (PK) parameters were calculated using baseline-corrected concentration-versus-time data following the last dose and noncompartmental techniques, as appropriate. The following PK parameters were calculated: baseline concentration (Cbaseline), maximum concentration (Cmax), average concentration at steady-state (Cav,ss), time to maximum concentration (tmax), minimum concentration (Cmin), and area under the concentration-time curve from time zero to last quantifiable concentration at time t (AUC0-t). Blood was collected on Day 13 at the indicated timepoints. If plasmapheresis was performed on a dosing day, blood samples were obtained before plasmapheresis, prior to study drug administration (post-plasmapheresis), and at time points relative to the start of infusion.

Plasma samples were used for the determination of functional C1 INH parameters. Primary pharmacokinetic (PK) parameters were calculated using baseline-corrected concentration-versus-time data following the last dose and noncompartmental techniques, as appropriate. The following PK parameters were calculated: baseline concentration (Cbaseline), maximum concentration (Cmax), average concentration at steady-state (Cav,ss), time to maximum concentration (tmax), minimum concentration (Cmin), and area under the concentration-time curve from time zero to last quantifiable concentration at time t (AUC0-t). Blood was collected on Day 13 at the indicated timepoints. If plasmapheresis was performed on a dosing day, blood samples were obtained before plasmapheresis, prior to study drug administration (post-plasmapheresis), and at time points relative to the start of infusion.