Treatment of steroid-refractory acute graft-versus-host disease with anti-CD147 monoclonal antibody ABX-CBL.

ABX-CBL, an immunoglobulin M murine monoclonal antibody, recognizes CD147 and initiates cell killing through complement-mediated lysis. In a dose-finding trial, 27 patients with steroid-refractory acute graft-versus-host disease (GVHD) received ABX-CBL at 0.01 (presumed no effect dose), 0.1, 0.2, or 0.3 mg/kg per day, and an additional 32 patients were given ABX-CBL at 0.2 or 0.15 mg/kg per day. All patients had undergone allogeneic transplantation for malignant or nonmalignant disorders and received GVHD prophylaxis, generally with methotrexate- and cyclosporine-containing regimens. None responded to methylprednisolone, given for a minimum of 3 days. ABX-CBL was started 20 to 236 (median, 47) days after transplantation; it was given for 7 consecutive days and was followed by 2 infusions per week for 2 more weeks. Among 51 patients evaluable for efficacy, 26 (51%) responded, including 13 with complete responses (CR) and 13 with partial responses (PR). CR lasting 14 days or longer or PR lasting 7 days or longer occurred in 21 (41%; 8 CR, 13 PR) patients, including 19 of 43 (44%) patients who received 0.1 to 0.3 mg/kg ABX-CBL and 2 of 8 (25%) patients given 0.01 mg/kg per day. Myalgias at doses 0.2 mg/kg or greater were dose limiting and resolved without sequelae. Causes of death included organ failure, progressive GVHD, and infection. No death was attributed to ABX-CBL. At 6 months after the initiation of ABX-CBL therapy, 26 (44%) patients were surviving. These results are encouraging. Further studies on the use of ABX-CBL in the management of GVHD are warranted.

Pharmacokinetics of a recombinant modified amino terminal fragment of bactericidal/permeability-increasing protein (rBPI21) in healthy volunteers.

Phase I pharmacokinetic and safety studies were conducted in healthy volunteers with rBPI21, a recombinant protein derived from the amino terminal domain of human bactericidal/permeability-increasing protein. rBPI21 was administered as a 30-minute infusion at doses of 0.25 to 4 mg/kg or as a 24- to 48-hour infusion at doses of 2 to 8 mg/kg. For the 30-minute infusions, the clearance of rBPI21 decreased with increasing dose from 8.4 mL/min/kg at 0.25 mg/kg to 3.3 mL/min/kg at 4 mg/kg. For rBPI21 infused over 24 to 48 hours the clearance was 10 to 11 mL/min/kg. The concentration-time profile of rBPI21 was well described by a three-compartmental model with parallel first-order and Michaelis-Menten (saturable) elimination. This model for the clearance of rBPI21 has been useful in estimating starting doses for therapeutic clinical trials.

Plasma bactericidal/permeability-increasing protein concentrations in critically ill children with the sepsis syndrome.

Bactericidal/permeability-increasing protein (BPI) is a neutrophil azurophilic granule component that is bactericidal towards Gram-negative bacteria and inhibits lipopolysaccharide-mediated inflammatory responses. We conducted a prospective study to measure plasma BPI concentrations in 36 critically ill children with and without the sepsis syndrome. Plasma BPI concentrations ranged from 0.5 to 452 ng/ml. Patients with the sepsis syndrome had higher median plasma BPI concentrations than critically ill controls (5.1 vs. 1.8 ng/ml, P = 0.006). Patients with organ system failure had higher median plasma BPI concentrations than those with no organ system failure (4.5 vs. 1.3 ng/ml, P = 0.001). Plasma BPI concentrations were positively associated with pediatric risk of mortality score (P = 0.03, rs = 0.4). These data provide the first clinical insights regarding the role of endogenous BPI production in critically ill children and suggest that BPI may play an important role in host defenses.