LAUSR

BACKGROUND Orelabrutinib is a second-generation Bruton tyrosine kinase inhibitor that improves the management of B-cell malignancies. The objective of this study was to develop and validate an LC-MS/MS method for quantifying orelabrutinib in human plasma. METHODS Plasma samples were processed using acetonitrile to precipitate proteins. Ibrutinib-d5 was used as the internal standard. The mobile phase comprised 10 mM ammonium formate containing 0.1% formic acid and acetonitrile (62:38, vol/vol). The multiple reaction monitoring transitions at m/z = 428.1 → 411.2 and 446.2 → 309.2 were selected for orelabrutinib and ibrutinib-d5, respectively, after ionization in the positive mode. RESULTS Total runtime was 4.5 minutes. The validated curve ranges were 1.00-500 ng/mL. This method exhibited acceptable selectivity, dilution integrity, matrix effects, and recovery. Interrun and intrarun accuracy ranged from -3.4% to 6.5%, and interrun and intrarun precision was between 2.8% and 12.8%. Stability was studied under different conditions. The incurred sample reanalysis demonstrated good reproducibility. CONCLUSIONS The LC-MS/MS method provided a simple, specific, and rapid quantification of orelabrutinib in the plasma of patients with mantle cell lymphoma or chronic lymphocytic leukemia/small lymphocytic lymphoma. The results indicated that orelabrutinib exhibits large variability between individuals and should be prudently used in combination with CYP3A4 inhibitors.