The preclinical pharmacology of the high affinity anti-IL-6R Nanobody® ALX-0061 supports its clinical development in rheumatoid arthritis

Table 1 In vitro characterization of ALX-0061 using functional neutralization assays

Assay	Target	IC₅₀ (nM) without HSA	IC₅₀ (nM) with 15 μM HSA
sIL-6R neutralization potency ELISA	recombinant sIL-6R	0.07 ± 0.02 (n = 5)	0.06 ± 0.01 (n = 3)
Plasma potency ELISA	endogenous sIL-6R	NA	0.26 ± 0.03 (n = 3)
TF-1 cell-based proliferation assay	mIL-6R	0.29 ± 0.03 (n = 3)	0.77 ± 0.18 (n = 3)

In vitro activity of ALX-0061 was assessed using three different assays. The mean IC₅₀ ± SD is shown of multiple experiments, with the number of experiments indicated between brackets. 15 μM HSA should saturate ALX-0061 concentrations in these experiments. ELISA: enzyme-linked immunesorbent assay; HSA: human serum albumin; IC50: half minimal (50 %) inhibitory concentration; IL-6: interleukin-6; IL-6R: IL-6 receptor; mIL-6R: membrane IL-6R; NA: not applicable; SD: standard deviation; sIL-6R: soluble IL-6R

ISSN: 1478-6362