Aims: This investigation characterised tolerability, pharmacokinetics and pharmacodynamics of the anti-CD38 antibody TAK-079.

Methods: A randomised, double-blind, placebo-controlled trial of a single intravenous (i.v.) infusion or subcutaneous (s.c.) injection of TAK-079 at escalating doses in healthy subjects (n = 74), who were followed for 92 days postexposure.

Results: TAK-079 was well tolerated. All adverse events were mild or moderate. There were no withdrawals, infusion, or injection site reactions over the tested i.v. and s.c. doses up to 0.06 and 0.6 mg kg^-1 , respectively. At higher doses, transient cytokine level increases, following i.v. administration, coincided with reduction in CD38-expressing cells; clinical symptoms included mild pyrexia, headache, and postural hypotension. Following an i.v. infusion of 0.06 mg kg^-1 TAK-079, maximum observed serum concentration (C_max ) was 100.4 (%CV: 52) ng mL^-1 , time to C_max was the end of infusion and natural killer (NK_ cells were reduced 93.8 (±8.5) % from baseline levels. Following a s.c. injection of 0.6 mg kg^-1 TAK-079, C_max was 23.0 (%CV: 67) ng mL^-1 with time to C_max of 24 (range 7.98-96.02) hours, and plasmablasts were subsequently reduced 93.4 (±8.8) % from predose levels. Serum immunoglobulin (Ig)M, IgA and IgG levels were reduced by 15-60% and had not returned to baseline levels within 78 days after administration at ≥0.3 mg kg^-1 s.c. Reductions in NK cells at 0.6 mg kg^-1 s.c. were approximately 2-3 times more durable than at 0.06 mg kg^-1 i.v.

Conclusions: TAK-079 was well tolerated and s.c. administration elicited more durable reductions in plasmablasts and NK cells. This plasmacytolytic profile could be useful for treating disorders caused by plasma or NK cells, malignant counterparts, and/or pathogenic antibodies.

By Eric R Fedyk, Lin Zhao, Annelize Koch, Glennda Smithson, Jose Estevam, Grace Chen, Gezim Lahu, Stefan Roepcke, Jianchang Lin, Lachy Mclean