Development, validation, and clinical application of LC-MS/MS method for simultaneous determination of ibrutinib, zanubrutinib, orelabrutinib, acalabrutinib, and their active metabolites in patients with B-cell lymphoma

Bruton's tyrosine kinase inhibitors (BTKis) exhibit significant interindividual pharmacokinetics, making therapeutic drug monitoring (TDM) a promising approach for personalized therapy. However, simultaneous quantification of multiple BTKis poses technical challenges. A unified protocol for BTKis detection would be clinically desirable. Herein, we developed and validated a novel LC-MS/MS method for the simultaneous analysis of four BTKis including ibrutinib (IBR), zanubrutinib (ZAN), orelabrutinib (ORE), and acalabrutinib (ACB) and active metabolite of IBR and ACB (DIH and ACBM, respectively) in human plasma. The samples were prepared by liquid-liquid extraction using tert-butyl methyl ether. Ibrutinb-d4 (IS) was used as an internal standard. Chromatographic separation was obtained on an XBridge C18 column and connected to an LC-30AD system coupled to an API 4000⁺ mass spectrometer. The mobile phase comprised 10 mM ammonium acetate containing 0.1% formic acid and acetonitrile containing 0.1% formic acid. The optimized multiple reaction monitoring transitions of m/z 441.4 → 138.3, 475.4 → 304.2, 472.5 → 455.5, 428.3 → 411.5, 466.1 → 372.2, 482.2 → 388.4, and 445.5 → 142.5 were selected to inspect IBR, DIH, ZAN, ORE, ACB, ACBM, and IS, respectively. The method exhibited linearity from 1 to 1000 ng/mL (r > 0.99) for all analytes, with intra-day and inter-day precision of 1.8 to 9.7% and accuracy below 15%. Recovery ranged from 90.4 to 113.6%, and matrix effect varied from 89.3 to 111.0%. All compounds demonstrated stability under relevant conditions. Application of the method to 57 blood samples from 18 patients demonstrated high interpatient variability, with ORE plasma concentrations ranging from 25.6 to 89.9%. The validated LC-MS/MS method provides a feasible, specific, and rapid approach for quantification of BTKis in clinical settings. Simultaneous determination of four BTKis and their metabolites in a single extraction process and chromatographic run reduces analysis time, cost, and resources. The observed variability among individuals highlights the value of TDM for personalized treatment.