Discovery and Preclinical Characterization of BIIB091, a Reversible, Selective BTK Inhibitor for the Treatment of Multiple Sclerosis.

Multiple Sclerosis is a chronic autoimmune neurodegenerative disorder of the central nervous system (CNS) that is characterized by inflammation, demyelination, and axonal injury leading to permeant disability. In the early stage of MS, inflammation is the primary driver of the disease progression. There remains an unmet need to develop high efficacy therapies with superior safety profiles to prevent the inflammation processes leading to disability. Herein, we describe the discovery of BIIB091, a structurally distinct orthosteric ATP competitive, reversible inhibitor that binds the BTK protein in a DFG-in confirmation designed to sequester Tyr-551, an important phosphorylation site on BTK, into an inactive conformation with excellent affinity. Preclinical studies demonstrated BIB091 to be a high potency molecule with good drug-like properties and a safety/tolerability profile suitable for clinical development as a highly selective, reversible BTKi for treating autoimmune diseases such as MS.

Next-generation Bruton's tyrosine kinase inhibitor BIIB091 selectively and potently inhibits B cell and Fc receptor signaling and downstream functions in B cells and myeloid cells.

OBJECTIVES: Bruton's tyrosine kinase (BTK) plays a non-redundant signaling role downstream of the B-cell receptor (BCR) in B cells and the receptors for the Fc region of immunoglobulins (FcR) in myeloid cells. Here, we characterise BIIB091, a novel, potent, selective and reversible small-molecule inhibitor of BTK. METHODS: BIIB091 was evaluated in vitro and in vivo in preclinical models and in phase 1 clinical trial. RESULTS: In vitro, BIIB091 potently inhibited BTK-dependent proximal signaling and distal functional responses in both B cells and myeloid cells with IC50s ranging from 3 to 106 nm, including antigen presentation to T cells, a key mechanism of action thought to be underlying the efficacy of B cell-targeted therapeutics in multiple sclerosis. BIIB091 effectively sequestered tyrosine 551 in the kinase pocket by forming long-lived complexes with BTK with t 1/2 of more than 40 min, thereby preventing its phosphorylation by upstream kinases. As a key differentiating feature of BIIB091, this property explains the very potent whole blood IC50s of 87 and 106 nm observed with stimulated B cells and myeloid cells, respectively. In vivo, BIIB091 blocked B-cell activation, antibody production and germinal center differentiation. In phase 1 healthy volunteer trial, BIIB091 inhibited naïve and unswitched memory B-cell activation, with an in vivo IC50 of 55 nm and without significant impact on lymphoid or myeloid cell survival after 14 days of dosing. CONCLUSION: Pharmacodynamic results obtained in preclinical and early clinical settings support the advancement of BIIB091 in phase 2 clinical trials.

Recommendations for singlet-based approach in ligand binding assays: an IQ Consortium perspective.

Historically, ligand-binding assays for pharmacokinetic samples employed duplicate rather than singlet-based analysis. Herein, the Translational and absorption, distribution, metabolism and excretion (ADME) Sciences Leadership Group of the International Consortium for Innovation and Quality in Pharmaceutical Development (IQ) presents a study aiming to determine the value of duplicate versus singlet-based testing. Based on analysis of data collected from eight organizations for 20 drug candidates representing seven molecular types and four analytical platforms, statistical comparisons of validation and in-study quality controls and study unknown samples demonstrated good agreement across duplicate sets. Simulation models were also used to assess the impact of sample duplicate characteristics on bioequivalence outcomes. Results show that testing in singlet is acceptable for assays with %CV ≤15% between duplicates. Singlet-based approach is proposed as the default for ligand-binding assays while a duplicate-based approach is needed where imprecision and/or inaccuracy impede the validation of the assay.

Well-developed ligand-binding assays demonstrate robust performance using singlet analysis.

Aim: Replicate sample testing has long been regarded as a necessity for bioanalytical laboratory testing, especially in the realm of ligand-binding assays (LBAs). In an era in which results were derived from crude test tube-based assays, the replication of results was warranted. Those assays were often imprecise and required multiple replicates to arrive at results that approached accuracy. However, given technological advancements and excellent accuracy and precision of many modern LBAs, the practice of replicate testing should be re-evaluated. Although most regulatory guidelines allow for singlet testing when sufficient robustness and precision are demonstrated during validation, duplicate testing is still common practice. Recently however, several articles have been published that support singlet analysis for LBAs performed on a platform with automated liquid handling. Results: Data from five pharmacokinetic assay validations and five clinical and preclinical studies originally run in duplicate were re-evaluated in singlet and found to be nearly identical to the original duplicate results. Conclusion: We confirm that well-developed LBAs produce comparable data whether evaluated in singlet or duplicate. Additionally, automation is not requisite for singlet testing.

Effect of in vivo Hydroxychloroquine and ex vivo Anti-BDCA2 mAb Treatment on pDC IFNα Production From Patients Affected With Cutaneous Lupus Erythematosus.

Objective: Plasmacytoid dendritic cells (pDCs) are a major source of Type-I Interferon (IFN-I), a key driver in cutaneous lupus erythematosus (CLE). Currently evaluated in Phase II clinical trial, 24F4A (BIIB059) is an antibody targeting BDCA2, an inhibitory receptor expressed on pDCs. Given that Hydroxychloroquine (HCQ), a widely-used CLE therapy, and 24F4A are both able to inhibit pDC-derived IFN-I production; this study aimed to determine whether 24F4A would show an additional inhibitory effect on pDC response after ex vivo or in vivo treatment with HCQ. Methods: The effect of 24F4A on pDC-derived IFNα was measured from peripheral blood mononuclear cells (PBMC) either from healthy donors in presence or absence of HCQ or from CLE patients clinically exposed to various levels of HCQ. TLR7, TLR7/8, and TLR9 agonists (ssRNA, R848, and CpG-A) were used for pDC stimulation. Results: PDCs were the only producers of IFNα in response to CpG-A, R848, and ssRNA stimulation in PBMC cultures. CLE patients with higher levels of blood HCQ showed lower ex vivo pDC responses to CpG-A, but not R848 or ssRNA. In contrast, 24F4A reduced the amount of IFNα produced by pDCs from CLE patients in response to all TLR agonists, irrespective of the blood HCQ level. Conclusion: Our findings reveal that clinically-relevant HCQ concentrations partially inhibit the pDC response to TLR9 and weakly affect the response to TLR7/8 stimulation. 24F4A robustly inhibits pDC responses even in the presence of HCQ, highlighting its unique potential to disrupt pDC disease relevant biology, which could provide additional therapeutic benefit for CLE patients.

Evaluation of highly sensitive immunoassay technologies for quantitative measurements of sub-pg/mL levels of cytokines in human serum.

A comprehensive cross-platform and cross-assay evaluation using nine technology platforms and four cytokine immunoassays (IL-6, TNFα, IL-17a, IL-2) was performed by comparing assay precision, sensitivity, parallelism and data correlation between platforms. The precision was acceptable for most evaluated assays. In addition to comparing the analytical assay sensitivity using a spiked recombinant analyte in buffer, forty serum samples from both normal controls and multiple sclerosis patients were used to measure the frequency of endogenous analyte detection (FEAD) as a parameter of each assay's ability to detect the endogenous analyte. The highest FEAD measurements were observed on the Simoa™, Erenna®, Milliplex® and Imperacer® platforms. However, only Simoa and Erenna results showed a high correlation across all evaluated cytokine assays, followed by a more moderate correlation of results across platforms for the V-plex™, high sensitivity ELISA and the Ella™ IL-6 and TNFα assays. In contrast, results from the evaluated cytokine assays on the Milliplex, AMMP™ ViBE® and Imperacer platforms did not correlate to each other nor to other evaluated assays. Acceptable parallelism was observed for the Simoa, Erenna, V-plex and Ella assays but not for the Milliplex, AMMP ViBE and Imperacer assays. In conclusion, the Simoa, Erenna,V-plex and Ella platforms performed well in one or more evaluated cytokine assays. Among those, the Simoa and Erenna assays had the highest sensitivity for detection of cytokines present at sub-pg/mL levels in human serum. In addition, the cross-platform and cross-assay comparisons demonstrated that different immunoassays may yield different results, which underscores the importance of performing such comparative evaluations, especially in the absence of reliable reference standards for the quantitative assessments of biomarkers in immunoassays.