8FLL

Crystal structure of BTK kinase domain in complex with pirtobrutinib

Summary for 8FLL

• Entry DOI: 10.2210/pdb8fll/pdb
• Descriptor: Tyrosine-protein kinase BTK, pirtobrutinib, SULFATE ION, ... (6 entities in total)
• Functional Keywords: btk inhibitor, transferase, transferase-inhibitor complex, transferase/inhibitor
• Biological source: Homo sapiens (human)
• Total number of polymer chains: 1
• Total formula weight: 32755.45

Authors

Cedervall, E.P.,Morales, T.H.,Allerston, C.K. (deposition date: 2022-12-21, release date: 2023-03-01, Last modification date: 2024-05-22)

Primary citation

Gomez, E.B.,Ebata, K.,Randeria, H.S.,Rosendahl, M.S.,Cedervall, E.P.,Morales, T.H.,Hanson, L.M.,Brown, N.E.,Gong, X.,Stephens, J.,Wu, W.,Lippincott, I.,Ku, K.S.,Walgren, R.A.,Abada, P.B.,Ballard, J.A.,Allerston, C.K.,Brandhuber, B.J.
Preclinical characterization of pirtobrutinib, a highly selective, noncovalent (reversible) BTK inhibitor.
Blood, 142:62-72, 2023

PubMed Abstract: Bruton tyrosine kinase (BTK), a nonreceptor tyrosine kinase, is a major therapeutic target for B-cell-driven malignancies. However, approved covalent BTK inhibitors (cBTKis) are associated with treatment limitations because of off-target side effects, suboptimal oral pharmacology, and development of resistance mutations (eg, C481) that prevent inhibitor binding. Here, we describe the preclinical profile of pirtobrutinib, a potent, highly selective, noncovalent (reversible) BTK inhibitor. Pirtobrutinib binds BTK with an extensive network of interactions to BTK and water molecules in the adenosine triphosphate binding region and shows no direct interaction with C481. Consequently, pirtobrutinib inhibits both BTK and BTK C481 substitution mutants in enzymatic and cell-based assays with similar potencies. In differential scanning fluorimetry studies, BTK bound to pirtobrutinib exhibited a higher melting temperature than cBTKi-bound BTK. Pirtobrutinib, but not cBTKis, prevented Y551 phosphorylation in the activation loop. These data suggest that pirtobrutinib uniquely stabilizes BTK in a closed, inactive conformation. Pirtobrutinib inhibits BTK signaling and cell proliferation in multiple B-cell lymphoma cell lines, and significantly inhibits tumor growth in human lymphoma xenografts in vivo. Enzymatic profiling showed that pirtobrutinib was highly selective for BTK in >98% of the human kinome, and in follow-up cellular studies pirtobrutinib retained >100-fold selectivity over other tested kinases. Collectively, these findings suggest that pirtobrutinib represents a novel BTK inhibitor with improved selectivity and unique pharmacologic, biophysical, and structural attributes with the potential to treat B-cell-driven cancers with improved precision and tolerability. Pirtobrutinib is being tested in phase 3 clinical studies for a variety of B-cell malignancies.

PubMed: 36796019
DOI: 10.1182/blood.2022018674

Experimental method

X-RAY DIFFRACTION (1.498 Å)