Higher osimertinib introduction rate achieved by multiple repeated rebiopsy after acquired resistance to first/second generation EGFR-TKIs.

BACKGROUND: Indication for treatment with osimertinib after first/second generation (1/2G) epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI) resistance depends on T790M mutation detected by rebiopsy. The aim of our study was to analyze the data on clinical practice at our hospital where histological rebiopsy is actively carried out multiple times. METHODS: We retrospectively reviewed our electronic medical records of EGFR-mutant non-small cell lung cancer (NSCLC) patients to examine clinical rebiopsy situation, T790M detection rate, osimertinib introduction rate and associated outcomes. RESULTS: Among 95 patients with EGFR-mutant NSCLC, 72 patients received 1/2G EGFR-TKIs. Of 60 with progressive disease on 1/2G EGFR-TKIs, 50 (83%) underwent rebiopsy. T790M was detected in 40 (80%) of 50, resulting in a 79% osimertinib introduction rate, as one patient refused osimertinib. T790M was detected by first rebiopsy in 18 (36%) of 50 patients, and by second or subsequent rebiopsy in 22 (44%). Median time to treatment failure of T790M-positive patients at first rebiopsy was 22.6 (95% confidence interval [CI]: 10.2-32.8) months, and those at multiple repeated rebiopsy was 20.9 (95% CI: 8.6-not reached) months (p = 0.64). Median overall survival (OS) in osimertinib introduced group was 92.5 (95% CI: 62.9-not reached), while in nonosimertinib median OS was 39.0 months (95% CI: 22.2-not reached) (p = 0.04). CONCLUSIONS: T790M detection rate was increased by multiple repeated rebiopsy, achieving a higher osimertinib introduction rate. This higher introduction rate could contribute to better prognosis of EGFR-mutant NSCLC patients.

Phase II trial of gefitinib plus pemetrexed after relapse using first-line gefitinib in patients with non-small cell lung cancer harboring EGFR gene mutations.

OBJECTIVES: Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (i.e., EGFR-TKIs) improve the survival of lung cancer patients harboring EGFR mutations. Despite the initial efficacy of EGFR-TKIs, the disease progression caused by acquired resistance to these inhibitors is inevitable. T790M mutations represent a major resistance mechanism to EGFR-TKIs but can be overcome using osimertinib. The IMPRESS trial revealed that the continuation of EGFR-TKI beyond progressive disease (PD) concurrent with platinum-doublet chemotherapy was not beneficial. However, various clinical trials have suggested that EGFR-TKI beyond PD plus single-agent chemotherapy may be a possible treatment strategy. MATERIALS AND METHODS: This study was a single-arm phase II trial. Patients with EGFR-activating mutations (del19 and L858R) that progressed using first-line gefitinib treatment were enrolled and treated with gefitinib beyond PD plus pemetrexed 500 mg/m2 q3w. The primary endpoint was progression-free survival (PFS). Mutation-biased polymerase chain reaction quenching probe, which is the original method for detecting T790M mutations in cell-free plasma DNA, was used prior to treatment. RESULTS: Thirty-six patients were enrolled between May 1, 2013, and March 31, 2016. One patient was excluded before starting the treatment. Among the 35 patients, 15 patients had del19 mutations, and 20 patients had L858R mutations; 33 patients were evaluable for response by using radiographic findings. The median PFS was 6.7 months (95% confidence interval: 4.4-7.7 months). Nineteen patients were T790M positive. No significant difference in PFS was found in a subgroup analysis of EGFR mutation status and T790M positivity. All toxicities were tolerable. CONCLUSION: Gefitinib plus pemetrexed treatment following relapse using gefitinib in patients with Non-small cell lung cancer harboring EGFR mutations demonstrated preferable PFS with mild toxicity. This combination therapy may be considered for platinum-unfit patients without T790M with disease progression using first-line gefitinib. (This clinical trial was registered in UMIN-CTGR as UMIN000010709).

An LC-MS/MS Method for Absolute Quantification of Nivolumab in Human Plasma: Application to Clinical Therapeutic Drug Monitoring.

BACKGROUND: Nivolumab is a fully humanized IgG4 monoclonal antibody that targets the programmed death-1 (PD-1) receptor, disrupting PD-1-mediated signaling and restoring antitumor immunity. The objective of this study was to develop a nivolumab quantification method using liquid chromatography-tandem mass spectrometry (LC-MS/MS) and to evaluate its application in clinical therapeutic drug monitoring. METHODS: Nivolumab was purified from human plasma using rProtein A resin and then digested with trypsin. The ASGITFSNSGMHWVR peptide (multiple reaction monitoring transition: m/z 550.6→661.4) was detected as a surrogate peptide of nivolumab by triple quadrupole mass spectrometry. Plasma samples (126) were collected from 14 patients with non-small cell lung cancer who were undergoing clinical dosing regimen with nivolumab. The pharmacokinetic data were analyzed using Phoenix NLME software (Version 7.0, Certara, St. Louis, MO) based on a previously reported population pharmacokinetics (PPK) model of nivolumab. RESULTS: Nivolumab was selectively detected in human plasma and the linear range was 5-200 mcg/mL (R = 0.99). The accuracy and intraday and interday imprecision were within ±15% of the quality control values of 5 (lower limit of quantification), 10 (low), 80 (medium), and 160 (high) mcg/mL. The nivolumab concentrations measured using LC-MS/MS were consistent with those of previously reported PPK models, and the pharmacokinetic parameters could be adequately predicted from a single trough concentration using a Bayesian approach. CONCLUSIONS: An absolute quantification method for nivolumab using LC-MS/MS was successfully developed and validated. Combined with PPK analysis, this method should be useful for the therapeutic drug monitoring of nivolumab in clinical practice.

Development and validation of a method for gefitinib quantification in dried blood spots using liquid chromatography-tandem mass spectrometry: Application to finger-prick clinical blood samples of patients with non-small cell lung cancer.

A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for the quantification of gefitinib in dried blood spots (DBSs). Gefitinib was extracted with methanol from DBS of 3 mm in diameter and detected using a triple quadrupole mass spectrometer. The method was validated by evaluating its precision, accuracy, selectivity, carryover, matrix effect, recovery, and stability. For clinical validation, paired finger-prick DBS and plasma concentrations were compared for 10 patients with non-small cell lung cancer (NSCLC) taking gefitinib. The calibration linear range was 37.5-2400 ng/mL (coefficient of determination [R2] = 0.99), encompassing the therapeutic concentrations of gefitinib. The accuracy and precision were within 15% of the quality control (QC) concentrations of 80, 200, and 2000 ng/mL. The lower limit of quantification was determined to be 40 ng/mL. Gefitinib was stable in DBSs for up to 5 months at room temperature and -20 °C, and at 40 °C for 24 h. A good correlation was observed between the gefitinib levels measured by the DBS method and plasma concentrations (R2 = 0.99). This method provides a simple, fast, and accurate approach to the quantitative analysis of gefitinib in finger-prick DBSs. The method would be useful for minimally invasive evaluation of the clinical gefitinib blood concentration.