Analysis of the in vivo proliferative capacity of a whole cell cancer vaccine.

A polyvalent therapeutic cancer cell vaccine containing three viable, irradiated, replication-incompetent melanoma cell lines (Canvaxin) was administered to over 2500 patients in various clinical studies. This study examines the fate of Canvaxin cells in 16 patients with Stage II, III or IV melanoma, with special attention on assessing the capacity of the vaccine cells to replicate. The survival time and the potential proliferative capacity of irradiated Canvaxin cells in humans was studied by histologic examination of biopsies of injection sites over a two-week period. The overall results show that the vaccine cell mitotic index in skin biopsies (0.12%) was approximately 6 times lower than the control value (0.71%). Similarly, there was an overall trend toward a decrease in mitotic figures during the two week observation periods. Also, there was a trend towards a decrease in the number of vaccine cells and mitotic figures with increasing cycles. The data indicate that Canvaxin cells do not proliferate after intra-dermal injection, and that cells typically associated with an immune response are present at the inoculation sites.

Recommendations for the design and optimization of immunoassays used in the detection of host antibodies against biotechnology products.

Most biopharmaceutical therapeutics elicit some level of antibody response against the product. This antibody response can, in some cases, lead to potentially serious side effects and/or loss of efficacy. Therefore, the immunogenicity of therapeutic proteins is a concern for clinicians, manufacturers and regulatory agencies. In order to assess immunogenicity of these molecules, appropriate detection, quantitation and characterization of antibody responses are necessary. Inadequately designed antibody assays have led to the hampering of product development or, during licensure, post-marketing commitments. This document provides scientific recommendations based on the experience of the authors for the development of anti-product antibody immunoassays intended for preclinical or clinical studies. While the main focus of this document is assay design considerations, we provide scientific focus and background to the various assay performance parameters necessary for developing a valid assay. Sections on assay performance parameters, including those that appear in regulatory guidances, are contained in this manuscript.

Pharmacokinetics of rhuMAb CD18, a recombinant humanised monoclonal antibody fragment to CD18, in normal healthy human volunteers.

BACKGROUND AND OBJECTIVES: 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. STUDY DESIGN AND 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.