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

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Clin Transl Immunology. 2021 Jun 14;10(6):e1295. doi: 10.1002/cti2.1295. eCollection 2021.

ABSTRACT

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.

PMID:34141433 | PMC:PMC8204096 | DOI:10.1002/cti2.1295