Population Pharmacokinetics, Pharmacogenomics, and Adverse Events of Osimertinib and its Two Active Metabolites, AZ5104 and AZ7550, in Japanese Patients with Advanced Non-small Cell Lung Cancer: a Prospective Observational Study.

BACKGROUND: Potential novel strategies for adverse event (AE) management of osimertinib therapy, including therapeutic drug monitoring and the use of biomarkers, have not yet been fully investigated. This study aimed to evaluate (1) the relationship between exposure to osimertinib, especially its active metabolites (AZ5104 and AZ7550), and AEs, and (2) the relationship between germline polymorphisms and AEs. METHODS: We conducted a prospective, longitudinal observational study of 53 patients with advanced non-small cell lung cancer receiving osimertinib therapy from February 2019 to April 2022. A population pharmacokinetic model was developed to estimate the area under the serum concentration-time curve from 0 to 24 h (AUC0-24) of osimertinib and its metabolites. Germline polymorphisms were analyzed using TaqMan® SNP genotyping and CycleavePCR® assays. RESULTS: There was a significant association between the AUC0-24 of AZ7550 and grade ≥ 2 paronychia (p = 0.043) or anorexia (p = 0.011) and between that of osimertinib or AZ5104 and grade ≥ 2 diarrhea (p = 0.026 and p = 0.049, respectively). Furthermore, the AUC0-24 of AZ5104 was significantly associated with any grade ≥ 2 AEs (p = 0.046). EGFR rs2293348 and rs4947492 were associated with severe AEs (p = 0.019 and p = 0.050, respectively), and ABCG2 rs2231137 and ABCB1 rs1128503 were associated with grade ≥ 2 AEs (p = 0.008 and p = 0.038, respectively). CONCLUSION: Higher exposures to osimertinib, AZ5104, and AZ7550 and polymorphisms in EGFR, ABCG2, and ABCB1 were related to higher severity of AEs; therefore, monitoring these may be beneficial for osimertinib AE management.

Development and validation of a new liquid chromatography-tandem mass spectrometry assay for the simultaneous quantification of afatinib, dacomitinib, osimertinib, and the active metabolites of osimertinib in human serum.

Reports on the therapeutic drug monitoring (TDM) of second- and third-generation epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) in non-small cell lung cancer patients are limited and are required to improve the safety of EGFR-TKI therapy. Some EGFR-TKIs have active metabolites with similar or higher potency compared with the parent compounds; thus, monitoring the parent compound as well as its active metabolites is essential for truly effective TDM. In this study, we developed and validated a method that simultaneously quantifies second- and third-generation EGFR-TKIs (afatinib, dacomitinib, and osimertinib) and the active metabolites of osimertinib, AZ5104 and AZ7550, in the human serum using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The clinical application of the method was also evaluated. The analytes were extracted from a 100 µL serum sample using a simple protein precipitation method and analyzed using LC-MS/MS. Excellent linearity of calibration curves was observed at ranges of 2.5-125.0 ng/mL for afatinib, 2.5-125.0 ng/mL for dacomitinib, 4.0-800.0 ng/mL for osimertinib, 1.0-125.0 ng/mL for AZ5104, and 2.5-125.0 ng/mL for AZ7550. The precision and accuracy were below 14.9% and within ± 14.9% of the nominal concentrations, respectively. The mean recovery was higher than 94.7% and the coefficient of variation (CV) was lower than 8.3%. The mean internal-standard normalized matrix factors ranged from 94.6 to 111.9%, and the CVs were lower than 9.7%. This analytical method met the acceptance criteria of the U.S. Food and Drug Administration guidelines. The method was also successfully applied to the analysis of 45 clinical samples; it supports the efficient and valuable analysis for TDM investigations of EGFR-TKIs.

Discovery of a New STAT3 Inhibitor Acting on the Linker Domain.

Signal transducer and activator of transcription 3 (STAT3) is a latent transcription factor that contributes to tumor cell growth and survival and is often constitutively active in several types of cancers, which makes it an attractive target for cancer therapy. We identified 5,5'-(pentane-1,5'-diyl)bis(2-methyl-1,4-benzoquinone) (BPMB) as a new STAT3 inhibitor. BPMB inhibited the transcriptional activities of STAT3, despite its inability to reduce the phosphorylation and nuclear translocation of STAT3. BPMB selectively inhibited the proliferation of human breast cancer cell lines with constitutively activated STAT3. Furthermore, a gel retardation pattern was obtained by immunoblotting only when those STAT3-activated cell lines were treated with BPMB. The shifted bands could be immunoblotted with anti-STAT3 antibody but not with anti-STAT1/STAT5 antibody, and were stable under reducing conditions. The purified recombinant STAT3 protein treated with BPMB afforded a similar band shift pattern. Matrix-assisted laser desorption/ionization-mass spectrometry analysis of the component comprising the main shifted band suggested that the complex is a STAT3 homodimer crosslinked by BPMB through a Michael addition with Cys550 in the linker domain. Alanine replacement at this position resulted in reduction of the STAT3 dimer formation in the gel retardation assay. Thus, our results suggest that BPMB inhibits the proliferation of STAT3-activated cell lines, presumably through acylation of the linker domain and subsequent induction of the inactive STAT3 complexes.