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

Abstract

IntroductionThe pleiotropic cytokine interleukin-6 (IL-6) plays an important role in the pathogenesis of different diseases, including rheumatoid arthritis (RA). ALX-0061 is a bispecific Nanobody® with a high affinity and potency for IL-6 receptor (IL-6R), combined with an extended half-life by targeting human serum albumin. We describe here the relevant aspects of its in vitro and in vivo pharmacology.MethodsALX-0061 is composed of an affinity-matured IL-6R-targeting domain fused to an albumin-binding domain representing a minimized two-domain structure. A panel of different in vitro assays was used to characterize the biological activities of ALX-0061. The pharmacological properties of ALX-0061 were examined in cynomolgus monkeys, using plasma levels of total soluble (s)IL-6R as pharmacodynamic marker. Therapeutic effect was evaluated in a human IL-6-induced acute phase response model in the same species, and in a collagen-induced arthritis (CIA) model in rhesus monkeys, using tocilizumab as positive control.ResultsALX-0061 was designed to confer the desired pharmacological properties. A 200-fold increase of target affinity was obtained through affinity maturation of the parental domain. The high affinity for sIL-6R (0.19 pM) translated to a concentration-dependent and complete neutralization of sIL-6R in vitro. In cynomolgus monkeys, ALX-0061 showed a dose-dependent and complete inhibition of hIL-6-induced inflammatory parameters, including plasma levels of C-reactive protein (CRP), fibrinogen and platelets. An apparent plasma half-life of 6.6 days was observed after a single intravenous administration of 10 mg/kg ALX-0061 in cynomolgus monkeys, similar to the estimated expected half-life of serum albumin. ALX-0061 and tocilizumab demonstrated a marked decrease in serum CRP levels in a non-human primate CIA model. Clinical effect was confirmed in animals with active drug exposure throughout the study duration.ConclusionsALX-0061 represents a minimized bispecific biotherapeutic of 26 kDa, nearly six times smaller than monoclonal antibodies. High in vitro affinity and potency was demonstrated. Albumin binding as a half-life extension technology resulted in describable and expected pharmacokinetics. Strong IL-6R engagement was shown to translate to in vivo effect in non-human primates, demonstrated via biomarker deregulation as well as clinical effect. Presented results on preclinical pharmacological properties of ALX-0061 are supportive of clinical development in RA.Electronic supplementary materialThe online version of this article (doi:10.1186/s13075-015-0651-0) contains supplementary material, which is available to authorized users.

Profile of sarilumab and its potential in the treatment of rheumatoid arthritis

“…To date, other IL-6 blocking agents are currently under investigation in clinical trials for the treatment of rheumatic diseases. Some of them, such as sirukumab, olokizumab, and clazakizumab, are directly targeted on IL-6, whereas another (ALX-0061) binds to IL-6R, as listed in Table 1 77–83. In particular, the latter is an example of the promising application of nanobody technology to the treatment of rheumatic disorders, as already demonstrated for other targets in the pathogenesis of RA such as TNF84 and IL-1 85,86…”

VNARs: An Ancient and Unique Repertoire of Molecules That Deliver Small, Soluble, Stable and High Affinity Binders of Proteins

“…Camel VHH domains have also been isolated to serum albumins and successfully exploited to extend the serum half-life in vivo of a number of fusion partner proteins including other VHH domains. Published data [65] allows some degree of comparison to be made between the performance of an anti-albumin VHH domain and the E06 VNAR domain including (Table 1): species cross-reactivity, over all affinity, domain fusion flexibility and the resulting half-life extension of partner proteins. A good level of functional affinity is demonstrated by both domains classes with VNAR, at least in this comparison, showing a slight but significant improvement in terms of affinity and half-life extension over the equivalent VHH domain.…”

Single domain antibodies for the knockdown of cytosolic and nuclear proteins

“…Low affinity binders can be affinity-maturated by introducing CDR mutations, randomization of mutational hotspots or by error prone PCR. [35][36][37] The number of available inhibiting nanobodies against different cytosolic/nuclear proteins is increasing. So far most cytosolic/nuclear single domain intrabodies have been derived from camels, followed by some single domains VH and VL of human origin (Table I).…”