The CD25-binding antibody Daclizumab High-Yield Process has a distinct glycosylation pattern and reduced antibody-dependent cell-mediated cytotoxicity in comparison to Zenapax®.

The CD25-binding antibody daclizumab high-yield process (DAC HYP) is an interleukin (IL)-2 signal modulating antibody that shares primary amino acid sequence and CD25 binding affinity with Zenapax®, a distinct form of daclizumab, which was approved for the prevention of acute organ rejection in patients receiving renal transplants as part of an immunosuppressive regimen that includes cyclosporine and corticosteroids. Comparison of the physicochemical properties of the two antibody forms revealed the glycosylation profile of DAC HYP differs from Zenapax in both glycan distribution and the types of oligosaccharides, most notably high-mannose, galactosylated and galactose-α-1,3-galactose (α-Gal) oligosaccharides, resulting in a DAC HYP antibody material that is structurally distinct from Zenapax. Although neither antibody elicited complement-dependent cytotoxicity in vitro, DAC HYP antibody had significantly reduced levels of antibody-dependent cell-mediated cytotoxicity (ADCC). The ADCC activity required natural killer (NK) cells, but not monocytes, suggesting the effects were mediated through binding to Fc-gamma RIII (CD16). Incubation of each antibody with peripheral blood mononuclear cells also caused the down-modulation of CD16 expression on NK cells and the CD16 down-modulation was greater for Zenapax in comparison to that observed for DAC HYP. The substantive glycosylation differences between the two antibody forms and corresponding greater Fc-mediated effector activities by Zenapax, including cell killing activity, manifest as a difference in the biological function and pharmacology between DAC HYP and Zenapax.

Intermediate-affinity interleukin-2 receptor expression predicts CD56(bright) natural killer cell expansion after daclizumab treatment in the CHOICE study of patients with multiple sclerosis.

OBJECTIVE: The objective of this study was to evaluate whether interleukin-2 (IL-2) receptor expression on CD56(bright) natural killer (NK) cells predicted CD56(bright) NK cell expansion and therapeutic response to daclizumab (DAC) in multiple sclerosis (MS). METHODS: DAC exposure, CD56(bright) NK cell counts, IL-2 receptor alpha (CD25) and beta (CD122) subunits, and new or enlarged lesions on brain MRI were measured in 64 subjects in a pharmacokinetic/pharmacodynamic substudy of the phase 2 CHOICE trial at multiple time points. Peripheral blood mononuclear cell (PBMC) samples were obtained from healthy subjects to assess the relationship among DAC treatment, intermediate affinity IL-2 signaling, and CD56(bright) NK cell expansion. RESULTS: Increased CD56(bright) NK cell counts in DAC/interferon beta (IFNß)-treated subjects were observed by day 14, the first post-dosing time point (mean [SD] ln{CD56(bright) NK cell count}: DAC high/IFNß, 2.01 [1.25]; DAC low/IFNß, 2.29 [1.06]; placebo/IFNß, 1.01 [1.03]; adjusted p = 0.003), and persisted throughout the treatment period. Higher DAC dose predicted a faster rate of CD56(bright) NK cell expansion (p < 0.001), but individual subjects' increases in CD56(bright) NK cells from baseline levels were only weakly correlated with DAC exposure (r(2) = 0.167). Higher expression of the intermediate-affinity IL-2 receptor subunit (CD122) on CD56(bright) NK cells at baseline predicted fewer new gadolinium-enhanced (Gd+) lesions during the treatment period (1.77 vs. 0.62 adjusted mean new Gd+ lesions during weeks 8-24, lowest vs. highest quartile of percentage CD122(+) CD56(bright) NK cells; p = 0.033) and a greater increase in CD56(bright) NK cell counts at the end of DAC dosing (p = 0.029). CONCLUSION: CD56(bright) NK cell expansion after DAC treatment appears to reflect individual differences in the capacity for intermediate-affinity IL-2 signaling and could provide a basis for predicting clinical response to DAC in MS.

HuEP5C7 as a humanized monoclonal anti-E/P-selectin neurovascular protective strategy in a blinded placebo-controlled trial of nonhuman primate stroke.

Although inhibiting interaction of beta(2) integrins with cognate immunoglobulin class adhesion receptor ligands is an effective neuroprotective strategy in small mammal models of stroke, the strategy has failed in human trials. A completely different antiadhesion receptor strategy was therefore rigorously tested in a model that may more closely approximate human reperfused stroke. Early leukoadhesive events in postischemic cerebral microvessels are mediated by upregulated selectin-class adhesion receptors on endothelial cells. Therefore, a blocking antibody prepared against common P- and E-selectin epitopes was humanized to suppress complement activation and tested in a reperfused hemispheric stroke model in Papio anubis (baboon). Histological examination of postischemic cerebral microvessels revealed a strong upregulation of E-and P-selectin expression. Placebo-blinded administration of the humanized anti-human E- and P-selectin monoclonal antibody (HuEP5C7, 20 mg/kg IV, n=9; placebo, n=9) immediately after the onset of 1 hour of temporary ischemia resulted in trends showing reduced polymorphonuclear leukocyte (PMN) infiltration into ischemic cortex, reduced infarct volumes (by 41%), improved neurological score (by 35%), and improved ability to self-care (by 39%). Importantly, there was no evidence of systemic complement activation, immune suppression, or pathological coagulopathy associated with this therapy. These data suggest that a humanized anti-E/P-selectin antibody approach is safe and may be effective as a clinical treatment for human stroke.