Erlotinib Levels Research Articles

Humanization of SLCO2B1 in Rats Increases rCYP3A1 Protein Expression but Not the Metabolism of Erlotinib to OSI-420.

The organic anion transporting polypeptide (OATP)2B1 [(gene: solute carrier organic anion transporter family member 2B1 (SLCO2B1)] is an uptake transporter that facilitates cellular accumulation of its substrates. Comparison of SLCO2B1+/+ knockin and rSlco2b1-/- knockout rats showed a higher expression of rCYP3A1 in the humanized animals. We hypothesize that humanization of OATP2B1 not only affects cellular uptake but also metabolic activity. To further investigate this hypothesis, we used SLCO2B1+/+ and rSlco2b1-/ - rats and the OATP2B1 and rCYP3A1 substrate erlotinib, which is metabolized to OSI-420, for in vivo and ex vivo experiments. One hour after administration of a single dose of erlotinib, the knockin rats exhibited significantly lower erlotinib serum levels, but no change was observed in metabolite concentration or the OSI-420/erlotinib ratio. Similar results were obtained for liver tissue levels comparing SLCO2B1+/+ and rSlco2b1-/- rats. Liver microsomes isolated from the erlotinib-treated animals were characterized ex vivo for rCYP3A activity using testosterone, showing higher activity in the knockin rats. The contrary was observed when microsomes isolated from treatment-naïve animals were assessed for the metabolism of erlotinib to OSI-420. The latter is in contrast to the higher rCYP3A1 protein amount observed by western blot analysis in rat liver lysates and liver microsomes isolated from untreated rats. In summary, rats humanized for OATP2B1 showed higher expression of rCYP3A1 in liver and reduced serum levels of erlotinib but no change in the OSI-420/erlotinib ratio despite a lower OSI-420 formation in isolated liver microsomes. Studies with CYP3A-specific substrates are warranted to evaluate whether humanization affects not only rCYP3A1 expression but also metabolic activity in vivo. SIGNIFICANCE STATEMENT: Humanization of rats for the organic anion transporting polypeptide (OATP)2B1 increases rCYP3A1 expression and activity in liver. Using the OATP2B1/CYP3A-substrate erlotinib to assess the resulting phenotype, we observed lower erlotinib serum and liver concentrations but no impact on the liver/serum ratio. Moreover, there was no difference in the OSI-420/erlotinib ratio comparing humanized and knockout rats, suggesting that OSI-420 is not applicable to monitor differences in rCYP3A1 expression as supported by data from ex vivo experiments with rat liver microsomes.

Early [18]FDG PET/CT scan predicts tumor response in head and neck squamous cell cancer patients treated with erlotinib adjusted per smoking status.

Translational RelevanceEvaluation of targeted therapies is urgently needed for the majority of patients with metastatic/recurrent head and neck squamous cell carcinoma (HNSCC) who progress after immunochemotherapy. Erlotinib, a targeted inhibitor of epidermal growth factor receptor pathway, lacks FDA approval in HNSCC due to inadequate tumor response. This study identifies two potential avenues to improve tumor response to erlotinib among patients with HNSCC. For the first time, this study shows that an increased erlotinib dose of 300 mg in smokers is well-tolerated and produces similar plasma drug concentration as the regular dose of 150 mg in non-smokers, with increased study-specific defined tumor response. The study also highlights the opportunity for improved patient selection for erlotinib treatment by demonstrating that early in-treatment [18]FDG PET/CT is a potential predictor of tumor response, with robust statistical correlations between metabolic changes on early in-treatment PET (4-7 days through treatment) and anatomic response measured by end-of-treatment CT.PurposePatients with advanced HNSCC failing immunochemotherapy have no standard treatment options. Accelerating the investigation of targeted drug therapies is imperative. Treatment with erlotinib produced low response rates in HNSCC. This study investigates the possibility of improved treatment response through patient smoking status-based erlotinib dose optimization, and through early in-treatment [18]FDG PET evaluation to differentiate responders from non-responders.Experimental designIn this window-of-opportunity study, patients with operable HNSCC received neoadjuvant erlotinib with dose determined by smoking status: 150 mg (E150) for non-smokers and 300 mg (E300) for active smokers. Plasma erlotinib levels were measured using mass spectrometry. Patients underwent PET/CT before treatment, between days 4-7 of treatment, and before surgery (post-treatment). Response was measured by diagnostic CT and was defined as decrease in maximum tumor diameter by ≥ 20% (responders), 10-19% (minimum-responders), and < 10% (non-responders).ResultsNineteen patients completed treatment, ten of whom were smokers. There were eleven responders, five minimum-responders, and three non-responders. Tumor response and plasma erlotinib levels were similar between the E150 and E300 patient groups. The percentage change on early PET/CT and post-treatment PET/CT compared to pre-treatment PET/CT were significantly correlated with the radiologic response on post-treatment CTs: R=0.63, p=0.0041 and R=0.71, p=0.00094, respectively.ConclusionThis pilot study suggests that early in-treatment PET/CT can predict response to erlotinib, and treatment with erlotinib dose adjusted according to smoking status is well-tolerated and may improve treatment response in HNSCC. These findings could help optimize erlotinib treatment in HNSCC and should be further investigated.Clinical Trial Registration https://clinicaltrials.gov/ct2/show/NCT00601913, identifier NCT00601913.

Feasibility of Extrapolating Randomly Taken Plasma Samples to Trough Levels for Therapeutic Drug Monitoring Purposes of Small Molecule Kinase Inhibitors.

Small molecule kinase inhibitors (SMKIs) are widely used in oncology. Therapeutic drug monitoring (TDM) for SMKIs could reduce underexposure or overexposure. However, logistical issues such as timing of blood withdrawals hamper its implementation into clinical practice. Extrapolating a random concentration to a trough concentration using the elimination half-life could be a simple and easy way to overcome this problem. In our study plasma concentrations observed during 24 h blood sampling were used for extrapolation to trough levels. The objective was to demonstrate that extrapolation of randomly taken blood samples will lead to equivalent estimated trough samples compared to measured Cmin values. In total 2241 blood samples were analyzed. The estimated Ctrough levels of afatinib and sunitinib fulfilled the equivalence criteria if the samples were drawn after Tmax. The calculated Ctrough levels of erlotinib, imatinib and sorafenib met the equivalence criteria if they were taken, respectively, 12 h, 3 h and 10 h after drug intake. For regorafenib extrapolation was not feasible. In conclusion, extrapolation of randomly taken drug concentrations to a trough concentration using the mean elimination half-life is feasible for multiple SMKIs. Therefore, this simple method could positively contribute to the implementation of TDM in oncology.

Phase I/II study of sorafenib in combination with erlotinib for recurrent glioblastoma as part of a 3-arm sequential accrual clinical trial: NABTC 05-02.

Receptor tyrosine kinases such as epidermal growth factor receptors (EGFRs) and their downstream signaling pathways such as the Ras-Raf-mitogen-activated protein kinase (MAPK) pathway play important roles in glioblastoma (GBM). This study investigated the safety, pharmacokinetics, and efficacy of sorafenib (Ras/Raf/MAPK inhibitor) in combination with erlotinib (EGFR inhibitor) for treatment of recurrent GBMs. Patients with recurrent GBM were eligible. A novel sequential accrual trial design was used, where patients were sequentially accrued into separate treatment arms in phase I and phase II investigations to optimize recruitment efficiency. In phase I, a standard 3 + 3 format was used to identify dose-limiting toxicities (DLTs), determine maximum tolerated dose (MTD), and investigate pharmacokinetics. Phase II followed a 2-stage design with the primary endpoint being 6-month progression-free survival (PFS6). Sixteen patients were recruited for phase I, and the MTD was determined to be sorafenib 200 mg twice daily and erlotinib 100 mg once daily. DLTs include Grade 3 hypertension, Grade 3 elevated liver transaminases, and Grade 4 elevated lipase. While erlotinib did not affect sorafenib levels, sorafenib reduced erlotinib levels. In phase II, 3 of 19 stage 1 participants were progression free at 6 months. This did not meet the predetermined efficacy endpoint, and the trial was terminated. This study identified the MTD and DLTs for sorafenib and erlotinib combination therapy for recurrent GBMs; however, efficacy data did not meet the primary endpoint. This study also demonstrates the feasibility of a novel sequential accrual clinical trial design that optimizes patient recruitment for multiarm studies, which is particularly effective for multicenter clinical trials.

Effect of various anticoagulants on the bioanalysis of drugs in rat blood: implication for pharmacokinetic studies of anticancer drugs.

BackgroundPharmacokinetic studies are vital in development and optimization of drugs. While blood samples can be collected either in EDTA, heparin or citrate containing tubes for the estimation of drug levels in plasma, EDTA tubes are more commonly used. The purpose of this study was to evaluate the effects of anticoagulants on bioanalysis of drugs. Six drugs used extensively in cancer therapy were selected. Albino wistar rats (N = 6 per drug) were dosed with one of the following drugs intraperitoneally—pemetrexed (50 mg/kg), imatinib (50 mg/kg), erlotinib (25 mg/kg), meropenem (60 mg/kg), 6-mercaptopurine (20 mg/kg) and voriconazole (6 mg/kg). Blood samples were collected 2 h after dosing (1 h in 6-mercaptopurine group due to short half-life) by terminal bleeding from the retro-orbital plexus. Blood was collected in each of Disodium ETDA, heparin, trisodium citrate (TSC) and no anticoagulant (plain) tubes. Drug levels in these samples were determined by validated HPLC assays. ANOVA with Tukey’s post hoc test was performed to identify statistically significant differences in drug concentrations in anticoagulant tubes. p < 0.05 was considered statistically significant.ResultsSignificant differences in concentration between anticoagulant tubes was observed in case of erlotinib (p = 0.013) and meropenem (p = 0.00), while borderline statistical significance for pemetrexed (p = 0.076). TSC tubes overestimated erlotinib levels, heparin tubes underestimated meropenem concentrations and EDTA tubes overestimated pemetrexed concentrations.ConclusionsCareful selection of anti-coagulant is necessary for accurate characterization of pharmacokinetics of drugs. Routine use of EDTA tubes may lead to erroneous interpretation of pharmacokinetic data.Electronic supplementary materialThe online version of this article (doi:10.1186/s40064-016-3770-4) contains supplementary material, which is available to authorized users.

Modeling Therapy Response and Spatial Tissue Distribution of Erlotinib in Pancreatic Cancer.

Pancreatic ductal adenocarcinoma (PDAC) is likely the most aggressive and therapy-resistant of all cancers. The aim of this study was to investigate the emerging technology of matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI IMS) as a powerful tool to study drug delivery and spatial tissue distribution in PDAC. We utilized an established genetically engineered mouse model of spontaneous PDAC to examine the distribution of the small-molecule inhibitor erlotinib in healthy pancreas and PDAC. MALDI IMS was utilized on sections of single-dose or long-term-treated mice to measure drug tissue distribution. Histologic and statistical analyses were performed to correlate morphology, drug distribution, and survival. We found that erlotinib levels were significantly lower in PDAC compared with healthy tissue (P = 0.0078). Survival of long-term-treated mice did not correlate with overall levels of erlotinib or with overall histologic tumor grade but did correlate both with the percentage of atypical glands in the cancer (P = 0.021, rs = 0.59) and the level of erlotinib in those atypical glands (P = 0.019, rs = 0.60). The results of this pilot study present MALDI IMS as a reliable technology to study drug delivery and spatial distribution of compounds in a preclinical setting and support drug imaging-based translational approaches. Mol Cancer Ther; 15(5); 1145-52. ©2016 AACR.

Concentrations of Erlotinib in Tumor Tissue and Plasma in Non–Small-Cell Lung Cancer Patients After Neoadjuvant Therapy

IntroductionTumors might not optimally respond to systemic therapy if minimal effective levels are not reached within the tumor. Erlotinib has mainly been studied in the adjuvant or palliative setting and, therefore, little is known about erlotinib tumor penetration. The purpose of this exploratory study was to investigate lung tumor tissue erlotinib concentrations after neoadjuvant therapy for non–small-cell lung cancer. Patients and MethodsPatients were treated preoperatively with erlotinib (150 mg once daily for 3 weeks) up to 48 hours before surgery. Plasma samples were collected during treatment. Surgical resection involved radical resection of the lung tumor and tumor biopsies were frozen directly after surgery. Erlotinib and O-desmethyl erlotinib concentrations in lung tumor tissue and predose plasma were determined using high performance liquid chromatography coupled with tandem mass spectrometry. ResultsThirteen evaluable patients were included. The mean plasma and lung tumor tissue erlotinib levels were 1222 ng/mL (SD, 678) and 149 ng/g (SD, 153), respectively. In 2 individual patients, erlotinib and O-desmethyl erlotinib concentrations in lung tumor tissue were detectable up to 13 days and 7 days after erlotinib intake, respectively. Mean erlotinib tissue concentrations extrapolated to a time point directly after intake of erlotinib were approximated at > 200 ng/g tissue, which is greater than the reported half maximal inhibitory concentration (IC50) of wild type epidermal growth factor receptor (EGFR) (183 ng/mL). ConclusionNo strong accumulation of erlotinib in lung tumor tissue was observed. Nevertheless, extrapolated intratumoral concentrations during erlotinib therapy were greater than the IC50 of wild type EGFR.

Abstract 4652: Cerebrospinal fluid pharmacokinetics and pharmacodynamics following high-dose erlotinib treatment in brain cancer patients

Abstract Patients with non-small cell lung cancer (NSCLC) who develop leptomeningeal metastases show significant clinical improvement following high-dose gefitinib therapy. Based on this data, we aimed to explore the effect of high-dose erlotinib on clinical response and CNS penetration in primary or metastatic CNS cancer. We selected patients who had received prior therapy for either primary glioma or for NSCLC with metastases to the brain and treated them with an alternate dosing regimen of erlotinib. Blood and cerebrospinal fluid (CSF) samples were collected at various time points to assess levels of erlotinib. We found that CSF concentrations of erlotinib were generally 2% that of plasma concentrations. Among the five patients examined, CSF concentrations of erlotinib reached up to 131 nM when high doses were administered at 600 to 1200 mg every four to six days. Additionally, drug clearance was decreased with an increased dosing regimen in one of the patients. In one patient, the area under the curve (AUC) estimations showed a 24% increase in the CSF versus only a 2% increase in the plasma following an increase from 150 mg to 600 mg of erlotinib. Moreover, longitudinal CSF samples were evaluated for expression and activation of EGFR as well as various other receptor tyrosine kinases, such as ErbB2, ErbB3, cMET and IGF1R, using the highly sensitive multiplexed immunoassay CEER© platform. The latter provides insight into the molecular makeup of the CNS cancer throughout the therapeutic regimen. Our clinical data on patients receiving erlotinib therapy for primary and metastatic CNS disease suggests that increased dosing of erlotinib, administered as a pulse dose every four to six days leads to increased CSF drug concentrations. In spite of the variations seen among different patients, we conclude that higher erlotinib dosing regimens can provide enhanced CNS penetration that may prove to be more effective in primary and metastatic CNS cancers especially when coupled with real-time molecular monitoring of the disease to help guide the clinician during the course of treatment. Citation Format: Sandra Pastorino, Sandeep C. Pingle, Emma Langley, Phillip Kim, Tiffany Juarez, Pengfei Jiang, Christopher Tucker, Txheng Yang, Marlon Saria, Sharat Singh, Santosh Kesari. Cerebrospinal fluid pharmacokinetics and pharmacodynamics following high-dose erlotinib treatment in brain cancer patients. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4652. doi:10.1158/1538-7445.AM2014-4652

Phase I/II study of neoadjuvant bevacizumab, erlotinib and 5-fluorouracil with concurrent external beam radiation therapy in locally advanced rectal cancer

To determine the maximal tolerated dose of erlotinib when added to 5-fluorouracil (5-FU) chemoradiation and bevacizumab and safety and efficacy of this combination in patients with locally advanced rectal cancer. Patients with Magnetic resonance imaging (MRI) or ultrasound defined T3 or T4 adenocarcinoma of the rectum and without evidence of metastatic disease were enrolled. Patients received infusional 5-FU 225 mg/M2/day continuously, along with bevacizumab 5 mg/kg days 14, 1, 15 and 29. Standard radiotherapy was administered to 50.4 Gy in 28 fractions. Erlotinib started at a dose of 50 mg orally daily and advanced by 50 mg increments in the subsequent cohort. Open total mesorectal excision was carried out 6-9 weeks following the completion of chemoradiation. Thirty-two patients received one of three dose levels of erlotinib. Erlotinib dose level of 100 mg was determined to be the maximally tolerated dose. Thirty-one patients underwent resection of the primary tumor, one refused resection. Twenty-seven patients completed study therapy, all of whom underwent resection. At least one grade 3-4 toxicity occurred in 46.9% of patients. Grade 3-4 diarrhea occurred in 18.8%. The pathologic complete response (pCR) for all patients completing study therapy was 33%. With a median follow-up of 2.9 years, there are no documented local recurrences. Disease-free survival at 3 years is 75.5% (confidence interval: 55.1-87.6%). Erlotinib added to infusional 5-FU, bevacizumab and radiation in patients with locally advanced rectal cancer is relatively well tolerated and associated with an encouraging pCR.

Correlation between erlotinib pharmacokinetics, cutaneous toxicity and clinical outcomes in patients with advanced non-small cell lung cancer (NSCLC)

ObjectivesAn association between skin toxicity and outcome has been reported for NSCLC patients treated with erlotinib. Several explanations have been suggested, including pharmacokinetic and pharmacogenomic variability. The purposes of this study were to characterize erlotinib pharmacokinetic and to correlate drug serum and urine levels to toxicity and outcomes in advanced NSCLC patients. MethodsPatients with stage IV NSCLC consecutively treated with erlotinib in second- or third-line were enrolled. Biological samples (blood, urine and tumor specimens) were collected. Erlotinib levels in serum and urine samples of all patients after 7 (T1) and 30 (T2) days of treatment were quantified by LC–MS/MS analysis, along with urinary 6β-hydroxycortisol/cortisol ratio, as marker of metabolic phenotype of the CYP3A4/5 enzyme. Results56 patients were recruited and for 46 all samples were available. At T1 erlotinib levels were 3.90 [2.13]μmol/l and 0.37 [2.90]μmol/mol creat in serum and urinary samples, respectively; at T2 drug concentrations were significantly lower (2.02 [4.05]μmol/l and 0.23 [4.47]μmol/mol creat, respectively). Patients with grade 3 skin toxicity showed serum T1 drug levels significantly higher than those with grade 0–2 (6.84 [2.28] vs. 3.08 [1.97]μmol/l, respectively, p=0.004) and had longer progression-free and overall survival. An inverse correlation between erlotinib serum levels and urinary 6β-hydroxycortisol/cortisol ratio was observed in patients with grade 3 skin toxicity. ConclusionsThese findings suggest that the pharmacokinetics and metabolism of erlotinib are related to skin toxicity and may support further studies where erlotinib dosing is tailored according to pharmacokinetic parameters.

Phase II trial of erlotinib in patients with advanced non-small-cell lung cancer harboring epidermal growth factor receptor mutations: additive analysis of pharmacokinetics

We conducted a phase II trial of erlotinib in patients with advanced non-small-cell lung cancer (NSCLC) harboring epidermal growth factor receptor (EGFR) mutations and evaluated the relationship between plasma concentration and efficacy of erlotinib. Patients who were previously treated but naive to epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors (TKIs), with advanced NSCLC harboring EGFR mutations, were enrolled. Erlotinib was given at 150 mg once daily until disease progression. The primary end point was objective response rate (ORR). Plasma trough levels of erlotinib were measured on Days 2 (D2) and 8 (D8) by high-performance liquid chromatography. In total, 29 patients were enrolled from September 2008 to January 2011. ORR was 61.5 % (95 % confidence interval [CI] 40.57–79.8) of 26 assessable patients. The median progression-free survival (PFS) and overall survival (OS) were 6.3 months and 16.9 months, respectively. Skin rash was observed in 24 patients, mostly at grade 1 or 2. Grade 2 pneumonitis was observed in one patient. We collected blood samples from 16 patients. The median PFS of the high and low D8/D2 ratio group was 11.2 months and 5.7 months, respectively (p = 0.044, hazard ratio = 0.301, 95 % CI 0.094–0.968). Erlotinib showed an ORR comparable to that seen in previous studies for patients with NSCLC harboring EGFR mutations, although response, the primary end point, did not reach the predetermined threshold level. The D8/D2 ratio of erlotinib plasma trough levels might be a predictive factor for PFS.

An evaluation of the possible interaction of gastric acid suppressing medication and the EGFR tyrosine kinase inhibitor erlotinib

ObjectivesAs the bioavailability of erlotinib is dependent on gastric pH, an increase in gastric pH via the concurrent use of gastric acid suppressive medications (AS) may reduce its bioavailability and efficacy. We retrospectively analyzed the BR.21 trial database to pragmatically evaluate the impact of AS use on the median plasma drug levels of erlotinib, adverse events and outcome of participants. MethodsMonthly median plasma levels of erlotinib were compared between participants utilizing AS and those who did not using a Wilcoxon test. Interaction p-value for AS users and AS non-users was performed using a multivariate Cox model with a time-dependent covariate for AS use. Grade 2 adverse events were compared using Fisher's Exact Test. ResultsThe median plasma erlotinib level was not significantly different between AS users and AS non-users, and AS use did not appear to incur a negative impact on PFS or OS (Interaction p-values: PFS p=0.16; OS p=0.81). AS users receiving erlotinib had a similar frequency of rash (50.5% vs. 42.0%, p=0.08) and a statistically higher rate of diarrhea (27.9% vs. 15.6%, p=0.001) compared to AS non-users. In addition, AS users had higher rates of infections (erlotinib arm: 33.7% vs. 20.0%, p<0.0001; placebo arm: 22.7% vs. 10.8%, p=0.02). ConclusionThis retrospective analysis found that the co-administration of AS and erlotinib did not appear to have a significant impact on the median plasma drug levels or outcome.

Abstract 3353: Effect of erlotinib on the pharmacokinetics of irinotecan and its metabolites: A drug-drug interaction study.

Abstract Purpose: Since irinotecan and erlotinib are used in treatment for non-small cell lung cancer (NSCLC), co-administration of these drugs might be an effective treatment for NSCLC. However, drug-drug interaction should be concerned because these drugs are metabolized by CYP3A4 and excreted into bile by ABC transporters. To clarify the drug-drug interaction when these drugs are co-administered, we examined the effect of this co-administration on the pharmacokinetics of irinotecan, its active metabolite 7-ethyl-10-hydroxycamptothecin (SN-38), SN-38 glucuronide (SN-38G) in animal model. Methods: Cytotoxicity of irinotecan and SN-38 with erlotinib against NSCLC cell line (A549) was assessed. To elucidate the effect of drug-drug interaction between irinotecan and erlotinib, male Sprague-Dawley rats were treated with 10 mg/kg irinotecan and 25 mg/kg erlotinib. The concentrations of irinotecan, SN-38, SN-38G and erlotinib in plasma, bile, and tissues were analyzed by high-performance liquid chromatography. Pharmacokinetic parameters were calculated by non-compartmental model methods. Results: Co-exposured erlotinib enhanced the cytotoxicity of SN-38 in a dose-dependent manner, however it did not significantly affect the cytotoxicity of irinotecan against A549 that is resistant to erlotinib. Additionally, co-administration of erlotinib resulted in a significant increase of plasma concentration of irinotecan, SN-38 and SN-38G compared to irinotecan alone, but decrease in the biliary excretion. Erlotinib significantly increased the concentration of irinotecan and SN-38G in kidney and that of SN-38 in lung and jejunum. On the other hand, co-administration of irinotecan intended to decrease the plasma concentration of erlotinib but significant differences of pharmacokinetic parameters were not observed. Also, levels of erlotinib in tissues were not affected by co-administration of irinotecan. Conclusions: We proposed the possibility of combination therapy of irinotecan with erlotinib because the plasma concentration of irinotecan and its active metabolite SN-38 significantly increased in vivo and the cytotoxicity of SN-38 against NSCLC cell line enhanced. New effective salvage chemotherapy regimens are needed in patients with NSCLC. We conducted a phase I/II clinical study of combination chemotherapy with irinotecan and erlotinib for recurrent NSCLC because our data have shown synergistic/additive effects between irinotecan and epidermal growth factor receptor-tyrosine kinase inhibitor. Citation Format: Emiko Sanematsu, Issei Toyooka, Yuki Takashima, Tamio Okimoto, Yukari Tsubata, Hideyuki Saito, Takeshi Isobe, Akinobu Hamada. Effect of erlotinib on the pharmacokinetics of irinotecan and its metabolites: A drug-drug interaction study. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3353. doi:10.1158/1538-7445.AM2013-3353

Quantitative Determination of Erlotinib And O -Desmethyl Erlotinib in Human Edta Plasma And Lung Tumor Tissue

To increase knowledge about lung tumor tissue levels of erlotinib and its primary active metabolite, and about erlotinib plasma levels in intercalated dosing schedules, a sensitive and accurate method for determination of erlotinib and O-desmethyl erlotinib (OSI-420) in human plasma and lung tumor tissue has been developed. A method with HPLC-MS/MS was validated over a linear range from 5 to 2500 ng/ml in plasma and from 5.0 to 500 ng/ml for lung tumor tissue homogenate (50-5000 ng/g for lung tumor). Calibration curves in plasma were used to quantify analytes in lung tumor tissue homogenate. Lung tumor tissue of 15 patients has been collected and analyzed with the presented method. This method has been successfully validated and applied to determine plasma and lung tumor tissue concentrations of erlotinib and O-desmethyl erlotinib in patients with non-small-cell lung cancer.

Skin rash as useful marker of erlotinib efficacy in NSCLC and its impact on clinical practice

Erlotinib is an epidermal growth factor receptor tyrosine kinase inhibitor used in treatment of advanced NSCLC. Patients harboring EGFR or KRAS mutations represent minority of all patients in caucasian population and there is no available predictor for a predominant group of patients harboring the wild-type EGFR and wild-type KRAS genes. Skin rash is the most frequent manifestation of cutaneous toxicity of erlotinib. Rash is associated with a good therapeutic response. We aimed at the evaluation of rash as a predictor of therapeutic effect of erlotinib in patients harboring the wild-type EGFR and KRAS wild-type genes and to assess its possible usage in a clinical practice.Totally 184 patients with advanced stage NSCLC (IIIB, IV) harboring the wild-type EGFR and wild-type KRAS genes were analysed. Comparison of ORR, PFS and OS according to the occurrence of rash was performed. In order to assess the impact of rash in clinical practice it was conducted landmark analysis of the group of patients whose rash was observed during first month of treatment (n=124). Patients in whom progression was observed during the first month of treatment were excluded from the landmark analysis. The comparison of ORR was performed using Fisher's exact test, visualization of survival was performed using Kaplan-Meier survival curves and the differences in survival were tested using the log-rank test. Median PFS in patients who were observed with rash during the treatment was 3.0 vs. 1.2 months in patients with no rash (p<0.001), median of OS in patients who were observed with rash during the treatment was 13.9 vs. 5.8 months in patients with no rash (p<0.001). ORR in patients who were observed with rash during the treatment was 17.4% vs. 3.3% in patients with no rash (p=0.001). Median of PFS after 1 month of treatment in patients who were observed with rash during the first month was 2.9 vs. 1.1 months in patients with no rash (p=0.027). Median of OS after 1 month of treatment in patients who were observed with rash during the first month was 13.8 vs. 9.9 months in patients with no rash (p=0.082). Rash is strongly associated with better survival and ORR in patients harboring wild-type EGFR and wild-type KRAS genes. Occurrence of rash during the first month of treatment is a useful predictor of better effect of erlotinib after one month of treatment. Patients who were not observed with rash during the first month of treatment are in high risk of progression. Optimization of the treatment of these patients can contribute restaging after two months of treatment, assessment of plasma levels of erlotinib and eventually attempt to dose escalation.

Skin Rash as Useful Marker of Erlotinib Efficacy in NSCLC and Its Impact on Clinical Practice

Erlotinib is an epidermal growth factor receptor tyrosine kinase inhibitor used in treatment of advanced NSCLC. Patients harboring EGFR or KRAS mutations represent minority of all patients in caucasian population and there is no available predictor for a predominant group of patients harboring the wild-type EGFR and wild-type KRAS genes. Skin rash is the most frequent manifestation of cutaneous toxicity of erlotinib. Rash is associated with a good therapeutic response. We aimed at the evaluation of rash as a predictor of therapeutic effect of erlotinib in patients harboring the wild-type EGFR and KRAS wild-type genes and to assess its possible usage in a clinical practice.Totally 184 patients with advanced stage NSCLC (IIIB, IV) harboring the wild-type EGFR and wild-type KRAS genes were analysed. Comparison of ORR, PFS and OS according to the occurrence of rash was performed. In order to assess the impact of rash in clinical practice it was conducted landmark analysis of the group of patients whose rash was observed during first month of treatment (n=124). Patients in whom progression was observed during the first month of treatment were excluded from the landmark analysis. The comparison of ORR was performed using Fisher's exact test, visualization of survival was performed using Kaplan-Meier survival curves and the differences in survival were tested using the log-rank test. Median PFS in patients who were observed with rash during the treatment was 3.0 vs. 1.2 months in patients with no rash (p<0.001), median of OS in patients who were observed with rash during the treatment was 13.9 vs. 5.8 months in patients with no rash (p<0.001). ORR in patients who were observed with rash during the treatment was 17.4% vs. 3.3% in patients with no rash (p=0.001). Median of PFS after 1 month of treatment in patients who were observed with rash during the first month was 2.9 vs. 1.1 months in patients with no rash (p=0.027). Median of OS after 1 month of treatment in patients who were observed with rash during the first month was 13.8 vs. 9.9 months in patients with no rash (p=0.082). Rash is strongly associated with better survival and ORR in patients harboring wild-type EGFR and wild-type KRAS genes. Occurrence of rash during the first month of treatment is a useful predictor of better effect of erlotinib after one month of treatment. Patients who were not observed with rash during the first month of treatment are in high risk of progression. Optimization of the treatment of these patients can contribute restaging after two months of treatment, assessment of plasma levels of erlotinib and eventually attempt to dose escalation.

Fatal interstitial lung disease associated with high erlotinib and metabolite levels. A case report and a review of the literature

IntroductionErlotinib is an agent in the class of oral epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors. Although this class of agents is considered to be relatively safe, the most serious, but rare, adverse reaction is drug-associated interstitial lung disease (ILD). This potentially fatal adverse reaction has been often described with gefitinib, but has been less well described for erlotinib. We here describe a case report of fatal interstitial lung disease in a Caucasian man associated with erlotinib and high erlotinib and metabolite plasma levels and discuss it in the context of all documented cases of erlotinib associated ILD. MethodsOur case was described and for the literature review a Pubmed and Google Scholar search was conducted for cases of erlotinib associated ILD. The retrieved publications were screened for relevant literature. ResultsBesides our case, a total of 19 cases of erlotinib-associated ILD were found. Eleven out 19 cases had a fatal outcome and in only one case erlotinib plasma concentrations were measured and found to be high. ConclusionErlotinib-associated ILD is a rare, serious and often fatal adverse reaction. Most likely, the cause for erlotinib-associated ILD is multifactorial and high drug levels may be present in patients without serious adverse reactions. However, considering the pharmacology of EGFR inhibitors, high drug and metabolite levels may play a role and future studies are warranted to identify risk factors and to investigate the role of elevated levels of erlotinib and its metabolites in the development of pulmonary toxicity.

Abstract 5459: Association of CYP1A1 and CYP3A5 polymorphisms with pharmacokinetics of erlotinib in patients with non-small cell lung cancer

Abstract Background: Erlotinib is a selective inhibitor of EGFR tyrosine kinase activity used for the treatment of patients with NSCLC. It has been reported that ABCB1 polymorphisms affect pharmacokinetics and adverse events of erlotinib in Japanese patients (Hamada A, 2009 AACR meeting). Erlotinib is metabolized by CYP3A4, CYP3A5, CYP1A1, and CYP1A2. The purpose of this study was to investigate the association of CYP1A1 and CYP1A5 single nucleotide polymorphisms (SNPs) with inter-individual variability of erlotinib pharmacokinetics. Methods: Patients with NSCLC were treated with single-agent oral erlotinib 150 mg/day. Plasma levels of erlotinib were measured by high-performance liquid chromatography on days 1 and at steady state (&amp;gt;day 8). DNA was obtained from whole blood, and genotyping was carried out using an Applied Biosystems TaqMan SNP Genotyping Assay on an ABI PRISM® 7900HT system. Results: Fifty patients (mean age, 67 years) were enrolled in the study. Histological classifications were: adenocarcinoma (n=41), squamous cell carcinoma (n=7), and unknown (n=2). Smoking history was indicated as: never smoker (n=23), former smoker (n=24), and current smoker (n=3). For the CYP3A5 6986A&amp;gt;G polymorphism, the frequencies of wild-type (AA), heterozygote (GA), and homozygote (GG) were 6%, 34%, and 60%, respectively. For the CYP1A1 2455A&amp;gt;G polymorphism, the frequencies of wild-type (AA), heterozygote (GA), and homozygote (GG) were 64%, 24%, and 12%, respectively. The mean (±SD) maximum concentrations (Cmax), trough concentrations (Ctrough) on day 1, and steady-state trough concentrations (Css) on &amp;gt;day 8 were 1.66±0.73 μg/mL, 0.77±0.5 μg/mL, and 1.5±0.8 μg/mL, respectively. Lower exposure levels of erlotinib were observed in patients carrying the CYP3A5 6986AA allele than in patients carrying one or two G alleles (GA, GG). The Cmax on day 1 in patients carrying the CYP3A5 AA and GA/GG alleles were 0.76±0.27 μg/mL and 1.78±0.69 μg/mL, respectively. (p=0.0198) On the other hand, patients carrying the CYP1A1 2455GG allele had higher Css than in patients carrying the CYP1A1 2455AA or the CYP1A1 2455GA alleles (2.3±1.16 μg/mL vs. 1.4±0.69 μg/mL, p=0.0161) Conclusion: These results suggested that the CYP3A5 6986A&amp;gt;G and CYP1A1 2455A&amp;gt;G polymorphisms affect the pharmacokinetics of erlotinib in Japanese patients. Further studies involving a larger sample size will be required to evaluate whether measurement of the CYP3A5 and the CYP1A1 polymorphisms may help to optimize erlotinib treatment in individual patients. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 5459. doi:10.1158/1538-7445.AM2011-5459

Erlotinib therapy for central nervous system hemangioblastomatosis associated with von Hippel-Lindau disease: a case report

There is a need for effective systemic therapy for central nervous system (CNS) hemangioblastomas (HBs). We report a case of erlotinib therapy for CNS HBs in a patient with von Hippel-Lindau disease, in whom the HBs were associated with diffuse leptomeningeal seeding. We provide the first report of paired serum and cerebrospinal fluid (CSF) levels of erlotinib while on standard dosing. The patient exhibited neurologic and imaging signs of recurrent CNS HBs and progressive leptomeningeal metastasis following surgery, radiation, and stereotactic radiosurgery. The patient was treated with erlotinib 150 mg daily. The patient achieved a minor response to erlotinib therapy, including clinical improvement, reduction in size of two enhancing brain lesions (one of which, however, proved at autopsy to be radiation necrosis) and stabilization of leptomeningeal enhancement. In addition, the CSF white count improved. The duration of response was 9 months. The median plasma and CSF levels of erlotinib while on treatment were 1146.06 and 247.83 ng/ml, respectively (CSF 21.6% of plasma). Erlotinib may have antitumor activity in CNS HBs.

A Multicenter Phase II Study of Erlotinib and Sorafenib in Chemotherapy-Naïve Patients with Advanced Non–Small Cell Lung Cancer

This multicenter, phase II study evaluates the efficacy and safety of erlotinib, an epidermal growth factor receptor (EGFR) inhibitor, plus sorafenib, a multityrosine kinase inhibitor against vascular endothelial growth factor receptors, in patients with previously untreated advanced non-small cell lung cancer (NSCLC). Chemotherapy-naïve patients with stage IIIB/IV NSCLC received erlotinib (150 mg once a day) and sorafenib (400 mg twice a day) until disease progression or unacceptable toxicity. The primary end point was the rate of nonprogression at 6 weeks. Secondary end points included objective response rate (ORR), time to progression, overall survival, and adverse events. Exploratory end points included pretreatment EGFR and KRAS mutation status, pharmacokinetics, and cytochrome P450 polymorphisms. Fifty patients initiated therapy. The nonprogression rate at 6 weeks was 74%: 12 (24%) partial response and 25 (50%) stable disease. Ultimately, the ORR was 28%. Median time to progression was 5.0 months [95% confidence interval (95% CI), 3.2-6.8 months]. Median overall survival was 10.9 months (95% CI, 3.8-18.1 months). Grade 3/4 adverse events included fatigue (16%), hand-foot skin reaction (16%), rash (16%), diarrhea (14%), and hypophosphatemia (42%). There was one treatment-related fatal pulmonary hemorrhage. Patients with wild-type EGFR had a higher ORR (19%) than previously reported for single-agent erlotinib/sorafenib. Erlotinib levels were lowered. This was associated with CYP3A4 polymorphism and was possibly due to sorafenib. Despite a possible drug interaction, sorafenib plus erlotinib has promising clinical activity in patients with stage IIIB/IV NSCLC and has an acceptable safety profile. Further evaluation of this combination as potential salvage therapy in EGFR mutation-negative patients and the possible drug interaction is warranted.