Glycosylation in the Fc region of antibodies has been shown to play an important role in antibody function. In the current study, glycosylation of human monoclonal antibodies was metabolically modulated using a potent alpha-mannosidase I inhibitor, kifunensine, resulting in the production of antibodies with oligomannose-type N-glycans. Growing Chinese hamster ovary cells for 11 days in batch culture with a single treatment of kifunensine was sufficient to elicit this effect without any significant impact on cell viability or antibody production. Antibodies expressed in the presence of kifunensine at a concentration as low as 60 ng/mL contained mainly oligomannose-type glycans and demonstrated increased ADCC activity and affinity for FcgammaRIIIA, but reduced C1q binding. Although the kifunensine-mediated shift to oligomannose-type glycans could, in theory, result in rapid clearance of the antibody through increased mannose receptor binding, the serum levels of antibody in mice were not significantly altered up to 168 h following injection. The use of kifunensine provides a simple and rapid method for the production of antibodies with increased ADCC without the time-consuming need to re-engineer either the antibody molecule or the host cell line.

Background Olipudase alfa, a recombinant human acid sphingomyelinase (rhASM), is an investigational enzyme replacement therapy (ERT) for patients with ASM deficiency [ASMD; Niemann-Pick Disease (NPD) A and B]. This open-label phase 1b study assessed the safety and tolerability of olipudase alfa using within-patient dose escalation to gradually debulk accumulated sphingomyelin and mitigate the rapid production of metabolites, which can be toxic. Secondary objectives were pharmacokinetics, pharmacodynamics, and exploratory efficacy. Methods Five adults with nonneuronopathic ASMD (NPD B) received escalating doses (0.1 to 3.0 mg/kg) of olipudase alfa intravenously every 2 weeks for 26 weeks. Results All patients successfully reached 3.0 mg/kg without serious or severe adverse events. One patient repeated a dose (2.0 mg/kg) and another had a temporary dose reduction (1.0 to 0.6 mg/kg). Most adverse events (97%) were mild and all resolved without sequelae. The most common adverse events were headache, arthralgia, nausea and abdominal pain. Two patients experienced single acute phase reactions. No patient developed hypersensitivity or anti-olipudase alfa antibodies. The mean circulating half-life of olipudase alfa ranged from 20.9 to 23.4 hours across doses without accumulation. Ceramide, a sphingomyelin catabolite, rose transiently in plasma after each dose, but decreased over time. Reductions in sphingomyelin storage, spleen and liver volumes, and serum chitotriosidase activity, as well as improvements in infiltrative lung disease, lipid profiles, platelet counts, and quality of life assessments, were observed. Conclusions This study provides proof-of-concept for the safety and efficacy of within-patient dose escalation of olipudase alfa in patients with nonneuronopathic ASMD.

Acute and extended exposure to grapefruit juice produces quantitatively similar inhibition of enteric, but not hepatic, CYP3A. Recovery is complete within 3 days after grapefruit juice discontinuation. Ritonavir greatly inhibits both enteric and hepatic CYP3A. With extended exposure to ritonavir, inhibition is the predominant effect, and recovery to baseline is nearly complete 3 days after ritonavir discontinuation.