Pharmacokinetics of rhuMAb CD18, a recombinant humanised monoclonal antibody fragment to CD18, in normal healthy human volunteers.
OBJECTIVE
Leucocyte 2 integrin adhesion receptors are hypothesised as a therapeutic target to modify immune responses to ischaemia-reperfusion injury that may be detrimental to recovery in a variety of disease states. Two phase I studies were designed to evaluate the pharmacokinetics, immunogenicity and safety of rhuMAb CD18, a humanised monoclonal antibody F(ab')(2) fragment to the CD18 receptor, in normal healthy human volunteers.


METHODS
The first study evaluated six escalating doses of rhuMAb CD18 (0.06, 0.12, 0.25, 0.5, 1.0, 2.0 mg/kg) in 36 subjects given two intravenous (IV) bolus injections 12 hours apart. In the second study, 16 subjects received IV doses of 1.0 and 2.0 mg/kg as a single dose or as two doses given 12 hours apart. Study endpoints were rhuMAb CD18 serum pharmacokinetics, change in white blood cell (WBC) count, and safety and tolerability. The two studies enrolled a total of 53 subjects.


RESULTS
Serum concentration-time profiles demonstrated a monophasic decline and were best characterised by a one-compartment pharmacokinetic model. At the doses administered, the volume of distribution approximated the serum volume (range of means: 42 to 58 ml/kg). The serum clearance decreased with increasing dose until becoming consistent at doses of 0.5 to 2.0 mg/kg (range of means: 3.1 to 5.0 ml/h/kg). At doses of 0.5 to 2.0 mg/kg, the mean elimination half-life ranged from 7.0 to 9.6 hours. WBC counts increased at doses of above 0.06 mg/kg, returning to within 20% of predose values by day 7. Antibodies to rhuMAb CD18 were not detected at day 28. Mild-to-moderate adverse events were observed in both the placebo and treated groups, and were limited to flu-like symptoms. One subject experienced a serious adverse event (febrile reaction) and recovered with minimal intervention. There was no evidence of an increase in infection in subjects who received rhuMAb CD18.


CONCLUSIONS
Upon IV bolus administration, rhuMAb CD18 serum concentration-time data fit a one-compartment pharmacokinetic model. At doses of 0.5 to 2.0 mg/kg, the pharmacokinetics were linear and the half-life ranged from 7.0 to 9.6 hours with a volume of distribution that approximated the serum volume. No antibodies to rhuMAb CD18 were detected. A transient, dose-dependent increase in the WBC count was observed, consistent with the expected effect of rhuMAb CD18 on leucocyte demargination. No increase in infection was observed. rhuMAb CD18 administered by IV bolus was well tolerated, with the exception of one febrile reaction.
Allison
David E
DE
Department of Clinical and Experimental Pharmacology, Genentech Inc., 1 DNA Way, MS70, South San Francisco, CA 94080, USA. allison2@gene.com
Gourlay
Steven G
SG
Koren
Eugene
E
Miller
Robert M
RM
Fox
Judith A
JA
D000328:Adult; D000911:Antibodies, Monoclonal / Q000008:administration & dosage / Q000009:adverse effects / Q000097:blood / Q000493:pharmacokinetics*; D000917:Antibody Formation; D019540:Area Under Curve; D018821:CD18 Antigens / Q000276:immunology*; D005260:Female; D006801:Humans; D007140:Immunoglobulin Fab Fragments / Q000008:administration & dosage* / Q000009:adverse effects / Q000097:blood / Q000378:metabolism*; D007275:Injections, Intravenous; D008297:Male; D008875:Middle Aged; D011994:Recombinant Proteins / Q000008:administration & dosage / Q000009:adverse effects / Q000097:blood / Q000493:pharmacokinetics*; D016037:Single-Blind Method
D000911:Antibodies, Monoclonal; D018821:CD18 Antigens; D007140:Immunoglobulin Fab Fragments; D011994:Recombinant Proteins