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 (AUC_0–24) of osimertinib and its metabolites. Germline polymorphisms were analyzed using TaqMan® SNP genotyping and CycleavePCR® assays. Results: There was a significant association between the AUC_0–24 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 AUC_0–24 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.

The optimal regimens of cefmetazole and flomoxef for the treatment of urinary tract infections caused by extended-spectrum β-lactamase (ESBL)-producing Enterobacterales are not well defined. Our study found that the pharmacokinetic/pharmacodynamic targets for cefmetazole and flomoxef were 70% T > MIC, which is suggestive of bactericidal activity. A Monte Carlo simulation (MCS) was performed using the published data to calculate a new probability of target attainment (PTA ≥ 90%) for each renal function. The MCS was performed with 1000 replicates, and clinical breakpoints were calculated to attain PTA ≥ 90% for creatinine clearance (CCR) of 10, 30, 50, and 70 mL/min. The 90% ≥ PTA (70% T > MIC) of cefmetazole and flomoxef in patients who received a standard regimen (0.5 or 1 g, 1 h injection) for each renal function was calculated. Our results suggest that in patients with CCR of less than 30, 31–59, and more than 60 mL/min, the optimal dosage of cefmetazole would be 1 g q12 h, 1 g q8 h, and 1 g q6 h, respectively. Furthermore, in patients with CCR of less than 10, 10–50, and more than 50 mL/min, the optimal dosage of flomoxef would be 1 g q24 h, 1 g q8 h or 12 h, and 1 g q6 h, respectively.

Background/Objectives: The increasing prevalence of urinary tract infections (UTIs) caused by extended-spectrum β-lactamase (ESBL)-producing organisms poses a significant clinical challenge worldwide due to limited oral treatment options. Tebipenem (TBPM), an oral carbapenem antibiotic, is currently approved only for pediatric use in Japan, with no adult indication established. International studies have shown promising results for ESBL-producing infections, but optimal dosing regimens for Japanese adults with varying renal function have not been established. This study aimed to determine the optimal TBPM dosing regimens for ESBL-producing Enterobacterales UTIs in Japanese patients stratified by renal function, providing evidence for potential adult approval applications in Japan. Methods: Monte Carlo simulations (MCSs) were performed using pharmacokinetic parameters derived from clinical trials in Japanese subjects. Various dosing regimens were evaluated across different creatinine clearance (CCR) ranges and minimum inhibitory concentrations (MICs). The pharmacokinetic/pharmacodynamic target was set at fAUC_0–24/MIC·1/tau ≥ 34.58, with a ≥90% probability of target attainment (PTA) considered optimal. Results: For patients with severe renal impairment (CCR < 30 mL/min), 150 mg q12 h achieved a >90% PTA against ESBL-producing organisms with an MIC of 0.03 mg/L. For moderate-to-severe renal impairment (30 ≤ CCR < 50 mL/min) and moderate renal impairment (50 ≤ CCR < 80 mL/min), 300 mg q8 h maintained a >90% PTA. For normal renal function (CCR ≥ 80 mL/min), 600 mg q8 h was required to achieve the target PTA. Conclusions: This first Japanese PK/PD analysis of TBPM in ESBL-producing UTIs provides evidence-based dosing recommendations across various renal function levels. TBPM, with appropriate renal-adjusted dosing, may offer an effective oral treatment option for patients who have traditionally required hospitalization for parenteral therapy.

Background/Objectives: In recent years, clinical pharmacometrics has become vital for drug development and clinical practice, particularly for predicting drug efficacy and safety. Population pharmacokinetic models are used for drugs for which therapeutic drug monitoring is recommended in clinical practice. Numerous population pharmacokinetic models have been developed for patients with similar clinical and demographic characteristics, resulting in reduced inter-individual variability. Despite the existence of diverse-population pharmacokinetic models, selecting an appropriate model for bedside use remains challenging. This study proposes a model-simulated model-based meta-analysis (M-cubed) to construct a unified model capable of accommodating a wide range of patient backgrounds. Methods: Vancomycin (VCM), a drug used for therapeutic drug monitoring, was used as an example. Using information from published VCM models, the M-cubed method was employed to generate virtual patient data for each publication through simulation, followed by modeling the integrated dataset. Results: Population pharmacokinetic analysis was performed on data from 19 virtual patient models, resulting in a total of 2303 cases. Covariates in the final model included creatinine clearance and body weight. The predictive ability of the model was robust. Conclusions: A model that integrates several population studies using the M-cubed method is required to address the need in clinical practice.