For many antibodies, each antigen-binding site binds to only one antigen molecule during the antibody's lifetime in plasma. To increase the number of cycles of antigen binding and lysosomal degradation, we engineered tocilizumab (Actemra), an antibody against the IL-6 receptor (IL-6R), to rapidly dissociate from IL-6R within the acidic environment of the endosome (pH 6.0) while maintaining its binding affinity to IL-6R in plasma (pH 7.4). Studies using normal mice and mice expressing human IL-6R suggested that this pH-dependent IL-6R dissociation within the acidic environment of the endosome resulted in lysosomal degradation of the previously bound IL-6R while releasing the free antibody back to the plasma to bind another IL-6R molecule. In cynomolgus monkeys, an antibody with pH-dependent antigen binding, but not an affinity-matured variant, significantly improved the pharmacokinetics and duration of C-reactive protein inhibition. Engineering pH dependency into the interactions of therapeutic antibodies with their targets may enable them to be delivered less frequently or at lower doses.

Dysregulation of the complement system is linked to the pathogenesis of a variety of hematological disorders. Eculizumab, an anti-complement C5 monoclonal antibody, is the current standard of care for paroxysmal nocturnal hemoglobinuria (PNH) and atypical hemolytic uremic syndrome (aHUS). However, because of high levels of C5 in plasma, eculizumab has to be administered biweekly by intravenous infusion. By applying recycling technology through pH-dependent binding to C5, we generated a novel humanized antibody against C5, SKY59, which has long-lasting neutralization of C5. In cynomolgus monkeys, SKY59 suppressed C5 function and complement activity for a significantly longer duration compared to a conventional antibody. Furthermore, epitope mapping by X-ray crystal structure analysis showed that a histidine cluster located on C5 is crucial for the pH-dependent interaction with SKY59. This indicates that the recycling effect of SKY59 is driven by a novel mechanism of interaction with its antigen and is distinct from other known pH-dependent antibodies. Finally, SKY59 showed neutralizing effect on C5 variant p.Arg885His, while eculizumab does not inhibit complement activity in patients carrying this mutation. Collectively, these results suggest that SKY59 is a promising new anti-C5 agent for patients with PNH and other complement-mediated disorders.

One of the problematic features of hepatocellular carciBackground. Matrix metalloproteinase 9 (MMP-9), a noma (HCC) is its rapid invasion into the portal venous sys-92-kd gelatinase/type IV collagenase, has been implitem. Even in small HCCs, microscopic vascular invasion is cated as playing an important role in cancer invasion found in more than 40% of the nodules. 1,2 Macroscopic portal and metastasis. A previous study showed that serum venous invasion is reported to be the worst single prognostic type IV collagenase activity correlated with metastasis factor, after partial hepatectomy, for HCC.3 Thus the detecby hepatocellular carcinoma (HCC). The aims of this tion of vascular invasion and its potential is important in study were to determine the plasma levels of immunoredetermining therapy and prognosis. At present, there is no active MMP-9 in patients with HCC and to compare the clinical laboratory test to predict the potential for or the ongolevels with the clinical features including vascular invaing activity of vascular invasion by HCC. Theoretically, the sion. Patients and Methods. This study included 100 pameasurement of the plasma levels of specific proteins that tients with HCC, 21 patients with chronic hepatitis (CH), are released by cancer cells and that are necessary for the 24 patients with liver cirrhosis (LC), and 138 healthy invasive process is a feasible approach to predict the tumor control subjects. Plasma MMP-9 levels were measured behavior. with a specific one-step sandwich enzyme immunoassay.Invasive tumor growth and metastasis involve complex Results. Plasma MMP-9 levels in HCC (62 [33 to 130 ng/ steps. 4,5 The initial steps include the degradation of stromal mL] median [25%, 75%], 13 to 660 ng/mL, minimum, maxi-architecture and of basement membrane components, espemum) were significantly elevated compared with those cially type IV collagen. Two kinds of type IV collagenase in in normal controls (36 [25 to 45], range, 2.8-70 ng/mL), in the matrix metalloproteinases family, 6 matrix metallopro-CH (28 [18 to 30], 13 to 66 ng/mL) and in LC (35 [26 to teinase 9 (MMP-9) (92-kd gelatinase/type IV collagenase) and 58], 16 to 86 ng/mL) (P õ .0000001; P Å .0000003; and P Å matrix metalloproteinase 2 (MMP-2) (72-kd gelatinase/type .00205, respectively). When the cut-off level was defined IV collagenase), have been implicated as playing a major role as 60 ng/mL from a receiver operating characteristic in the degradation of the basement membrane in cancer invacurve, plasma MMP-9 concentrations had a sensitivity sion and metastasis. 4,5 A correlation between the tumor secreof 53% and a specificity of 89% for the detection of HCC tion of MMP-9 7 as well as MMP-2, 8 and experimental metasfrom CH and LC. The levels were significantly higher in tasis has been reported. HCC patients with macroscopic portal venous invasionPreviously, type IV collagenase activity (probably a mix-(79 [36 to 160], 15-660 ng/mL) than those without the inva-ture of MMP-2 and MMP-9 activity) in the tissue homogenate sion (44 [27...

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MT expression decreases with the degree of histological differentiation and decreases with increasing tumor stage in HCC. In addition, MT expression may lower the antitumor effect of CBDCA.