Background/Purpose:

Proinflammatory cytokines cause joint inflammation and destruction in patients with rheumatoid arthritis, as exemplified by the therapeutic success of inhibiting tumor necrosis factor alpha (TNFα) by adalimumab (ADA) and inhibiting interleukin-6 receptor (IL-6R) by tocilizumab (TCZ). Such biologic agents and small molecule inhibitors, including methotrexate (MTX) and the recently approved tofacitinib (TOF), a Janus kinase inhibitor, have diverse and potentially overlapping biological effects. The purpose of this study was to use the human primary cell–based BioMAP platform to identify similar and discriminating biological activities of TCZ, ADA, MTX, and TOF.

Methods:

BioMAP systems model complex signaling networks in primary human cell types and have been used extensively to validate compounds and targets, identify mechanisms of action and potential toxicities, and determine phenotypic signatures.¹ TCZ, ADA, MTX, and TOF were profiled across a panel of 14 cell-based BioMAP systems containing early-passage primary human cells cultured alone or with different stimulus combinations. Compounds were profiled at concentrations that would cover their reported clinical plasma exposure for the respective approved dosing regimen. To examine the effects of compounds on IL-6 trans-signaling, parallel experiments were conducted in the presence of exogenous soluble IL-6R (sIL-6R). Compound-mediated perturbations of protein-based and clinically relevant biomarker readouts and other cellular events (eg, proliferation, cell cytotoxicity) were used to generate a biological activity plot (ie, BioMAP profile) that served as a multisystem signature of the activity for each compound.

Results:

TCZ significantly inhibited the expression of P-selectin (4H system), IL-8 (Sag system), TNFα (BT and HDFSAg systems), IP-10 and IL-17A (HDFSAg system), and CD69 (LPS and Mphg systems), consistent with anti-inflammatory and immunomodulatory effects. In general, little overlap was reported in the BioMAP profiles for TCZ, ADA, MTX, and TOF. TOF disrupted IL-17F, but not IL-17A, production in the HDFSAg system and showed dose-dependent selectivity; the phenotypic signatures of TOF at clinically relevant doses (<1 μM) were distinct from those at higher concentrations. sIL-6R induced additional activities in the BioMAP, including inflammation-related, novel immunomodulatory and tissue/matrix remodeling effects. Importantly, TCZ, but not ADA or TOF, completely blocked all sIL-6R–related activities at concentrations corresponding to clinical plasma exposure levels.

Conclusion:

TCZ, ADA, MTX, and TOF have markedly unique BioMAP signatures, indicating that these compounds exert different mechanisms of action. IL-6 signaling in BioMAP required the presence of sIL-6R for functional trans-signaling, which was fully reversed by TCZ but not by ADA or TOF at clinically relevant concentrations. The relevance of these findings requires confirmation in clinical studies.

Reference: 1. Berg EL et al. J Pharmacol Toxicol Methods. 2006;53:67-74.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/primary-human-cell-biomap-profiling-of-methotrexate-tocilizumab-adalimumab-and-tofacitinib-reveals-different-mechanisms-of-action-with-distinct-phenotypic-signatures/