Disposition of [14C]LY2606368 following intravenous administration in patients with advanced and/or metastatic solid tumours.

The disposition and metabolism of prexasertib, a CHK-1 inhibitor was characterised over a 120 h period following a single 170-mg intravenous dose of [14C]prexasertib (50 µCi) to 6 patients with advanced/metastatic solid tumours.The prexasertib safety profile was consistent with prior studies. Plasma, urine, and faeces were analysed for radioactivity, prexasertib, and metabolites. Geometric mean t1/2 in plasma was 34.2 h for prexasertib and 73.8 h for total radioactivity. Unchanged prexasertib accounted for approximately 9% of plasma total radioactivity, indicating extensive metabolism by the presence of circulating metabolites. Both renal and faecal excretion were identified as important routes of elimination since 41.8% (±12.9%) of the total administered radioactivity was recovered in the renal excretions and 32.2% (±7.28%) in the faecal excretions. Mean renal clearance was approximately 15% of the total systemic clearance, while biliary clearance was also low. Prexasertib was cleared predominantly by metabolism with only 23% of the dose recovered in excreta as intact drug. Radioactivity was eliminated predominantly within 72 h in urine, but faecal elimination was protracted.The metabolism of prexasertib was complex while primary metabolic clearance pathways involved were oxidative deamination, O-dealkylation, mono-oxidation, and possibly direct glucuronide conjugation. Although prexasertib was the major component in plasma, up to 11 metabolites were observed. The most abundant metabolites identified in plasma were glucuronides and none of these are expected to contribute to the pharmacological activity or pose a safety concern.

Phase I Study of CHK1 Inhibitor LY2603618 in Combination with Gemcitabine in Patients with Solid Tumors.

OBJECTIVE: LY2603618, a selective inhibitor of checkpoint kinase 1 (CHK1) and key regulator of the DNA damage checkpoint, may enhance the effects of antimetabolites. This phase I study defined the recommended phase II dose of LY2603618 combined with gemcitabine. PATIENTS AND METHODS: Patients with advanced/metastatic disease were administered doses of LY2603618 (70-250 mg/m2 or flat-fixed doses of 200 or 230 mg) after gemcitabine (1,000 mg/m2). Safety and pharmacokinetics (PK) were assessed. RESULTS: Among the 50 patients enrolled, frequent adverse events possibly related to study drug treatment included fatigue (44%), decreased platelets (42%), decreased neutrophils (32%), nausea (26%), and decreased hemoglobin (20%). Systemic exposure of LY2603618 increased dose dependently, while clearance was relatively dose independent. The mean LY2603618 half-life varied; however, the durations were still suitable for maintaining human exposures while minimizing accumulation. LY2603618 PK were not altered by gemcitabine administration. Plasma exposures that correlate with the maximal pharmacodynamic effect in nonclinical models were achieved for all doses. One patient with non-small cell lung cancer carcinoma achieved a partial response; 22 patients had stable disease. CONCLUSIONS: The maximum tolerated dose of LY2603618 combined with gemcitabine was 200 mg/m2, but a fixed LY2603618 dose of 230 mg combined with gemcitabine was selected as the recommended phase II dose.

Impact of Repeated Tail Clip and Saphenous Vein Phlebotomy on Rats Used in Toxicology Studies.

Sampling blood for toxicokinetic (TK) evaluation in rodents is typically performed using a satellite group of animals to avoid depleting the blood volume and inducing an additional stressor in the main study animals. This practice does not allow for direct comparison of individual animal toxicity to exposure. These studies evaluated serial collection of twelve, 40-µl blood samples from each rat from either a tail clip or a saphenous vein bleed and its impact on toxicologic parameters over 4- and 14-day periods. The results show the feasibility of successfully collecting TK samples from main study animals, using either of the two techniques. Both procedures were amenable to execution by a single technician using dried blood spot sampling. Any changes observed in the primary markers of erythroid mass between the nonbled control rats and repeat sampled rats were minimal and the range of values often overlapped. This technique would improve the quality of data generated from toxicology studies by allowing a direct comparison of systemic exposure to toxicity while at the same time reducing the number of rats by obviating the need for satellite groups.

Phase I dose escalation and pharmacokinetic evaluation of two different schedules of LY2334737, an oral gemcitabine prodrug, in patients with advanced solid tumors.

BACKGROUND: This Phase-I-study aimed to determine the recommended Phase-II-dosing-schedule of LY2334737, an oral gemcitabine prodrug, in patients with advanced/metastatic solid tumors. Pharmacokinetics, cytokeratin-18 (CK18) levels, genetic polymorphisms, and antitumor activity were additionally evaluated. METHODS: Patients received escalating doses of LY2334737 either every other day for 21 days (d) followed by 7 days-drug-free period (QoD-arm) or once daily for 7 days every other week (QD-arm). The 28 days-cycles were repeated until disease progression or unacceptable toxicity. Standard 3 + 3 dose-escalation was succeeded by a dose-confirmation phase (12 additional patients to be enrolled on the maximum tolerated dose [MTD]). RESULTS: Forty-one patients received QoD- (40-100 mg) and 32 QD-dosing (40-90 mg). On QoD, 3/9 patients experienced dose-limiting toxicities (DLTs) on the 100 mg dose (2 × G3 diarrhea, 1 × G3 transaminase increase); 1 additional DLT (G3 diarrhea) occurred during dose confirmation at 90 mg (12 patients). On QD, 1 patient each experienced DLTs on 60 mg (G3 transaminase increase) and 80 mg (G3 prolonged QTcF-interval); 2/7 patients had 3 DLTs on the 90 mg dose (diarrhea, edema, liver-failure; all G3). The MTD was established at 90 mg for the QoD-arm. Seven patients on QoD and 4 on QD achieved SD (no CR + PR). Pharmacokinetics showed a dose-proportional increase in exposure of LY2334737 and dFdC without accumulation after repeated dosing. Significant increases in CK18 levels were observed. Genetic polymorphism of the cytidine deaminase gene (rs818202) could be associated with ≥ G3 hepatotoxicity. CONCLUSIONS: Both schedules displayed linear pharmacokinetics and acceptable safety profiles. The recommended dose and schedule of LY2334737 for subsequent Phase-II-studies is 90 mg given QoD for 21 day.

Automated high-capacity on-line extraction and bioanalysis of dried blood spot samples using liquid chromatography/high-resolution accurate mass spectrometry.

RATIONALE: Pharmacokinetic data to support clinical development of pharmaceuticals are routinely obtained from liquid plasma samples. The plasma samples require frozen shipment and storage and are extracted off-line from the liquid chromatography/tandem mass spectrometry (LC/MS/MS) systems. In contrast, the use of dried blood spot (DBS) sampling is an attractive alternative in part due to its benefits in microsampling as well as simpler sample storage and transport. However, from a practical aspect, sample extraction from DBS cards can be challenging as currently performed. The goal of this report was to integrate automated serial extraction of large numbers of DBS cards with on-line liquid chromatography/high-resolution accurate mass spectrometry (LC/HRAMS) bioanalysis. METHODS: An automated system for direct DBS extraction coupled to a LC/HRAMS was employed for the quantification of midazolam (MDZ) and α-hydroxymidazolam (α-OHMDZ) in human blood. The target analytes were directly extracted from the DBS cards onto an on-line chromatographic guard column followed by HRAMS detection. No additional sample treatment was required. The automated DBS LC/HRAMS method was developed and validated, based on the measurement at the accurate mass-to-charge ratio of the target analytes to ensure specificity for the assay. RESULTS: The automated DBS LC/HRAMS method analyzed a DBS sample within 2 min without the need for punching or additional off-line sample treatment. The fully automated analytical method was shown to be sensitive and selective over the concentration range of 5 to 2000 ng/mL. Intra- and inter-day precision and accuracy was less than 15% (less than 20% at the LLOQ). The validated method was successfully applied to measure MDZ and α-OHMDZ in an incurred human sample after a single 7.5 mg dose of MDZ. CONCLUSIONS: The direct DBS LC/HRAMS method demonstrated successful implementation of automated DBS extraction and bioanalysis for MDZ and α-OHMDZ. This approach has the potential to promote workload reduction and sample throughput increase.

Disposition and metabolism of LY2603618, a Chk-1 inhibitor following intravenous administration in patients with advanced and/or metastatic solid tumors.

The disposition and metabolism of a Chk-1 inhibitor (LY2603618) was characterized following a 1-h intravenous administration of a single 250-mg dose of [14C]LY2603618 (50 µCi) to patients with advanced or metastatic solid tumors. LY2603618 was well tolerated with no clinically significant adverse events. Study was limited to three patients due to challenges of conducting ADME studies in patients with advanced cancer. Plasma, urine and feces were analyzed for radioactivity, LY2603618 and metabolites. LY2603618 had a half-life of 10.5 h and was the most abundant entity in plasma, accounting for approximately 69% of total plasma radioactivity. The second most abundant metabolites, H2 and H5, accounted for <10% of total circulating radioactivity. The major route of clearance was via CYP450 metabolism. The mean total recovery of radioactivity was 83%, with approximately 72% of the radioactivity recovered in the feces and approximately 11% in the urine. LY2603618 represented approximately 6% and 3% of the administered dose in feces and urine, respectively. A total of 12 metabolites were identified. In vitro phenotyping indicated that CYP3A4 was predominantly responsible for the metabolic clearance of LY2603618. Additionally, aldehyde oxidase was involved in the formation of a unique human and non-human primate metabolite, H5.

Pharmacogenomics of gemcitabine metabolism: functional analysis of genetic variants in cytidine deaminase and deoxycytidine kinase.

Gemcitabine (dFdC, 2',2'-difluorodeoxycytidine) is metabolized by cytidine deaminase (CDA) and deoxycytidine kinase (DCK), but the contribution of genetic variation in these enzymes to the variability in systemic exposure and response observed in cancer patients is unclear. Wild-type enzymes and variants of CDA (Lys27Gln and Ala70Thr) and DCK (Ile24Val, Ala119Gly, and Pro122Ser) were expressed in and purified from Escherichia coli, and enzyme kinetic parameters were estimated for cytarabine (Ara-C), dFdC, and its metabolite 2',2'-difluorodeoxyuridine (dFdU) as substrates. All three CDA proteins showed similar K(m) and V(max) for Ara-C and dFdC deamination, except for CDA70Thr, which had a 2.5-fold lower K(m) and 6-fold lower V(max) for Ara-C deamination. All four DCK proteins yielded comparable metabolic activity for Ara-C and dFdC monophosphorylation, except for DCK24Val, which demonstrated an approximately 2-fold increase (P < 0.05) in the intrinsic clearance of dFdC monophosphorylation due to a 40% decrease in K(m) (P < 0.05). DCK did not significantly contribute to dFdU monophosphorylation. In conclusion, the Lys27Gln substitution does not significantly modulate CDA activity toward dFdC, and therefore would not contribute to interindividual variability in response to gemcitabine. The higher in vitro catalytic efficiency of DCK24Val toward dFdC monophosphorylation may be relevant to dFdC clinical response. The substrate-dependent alterations in activities of CDA70Thr and DCK24Val in vitro were observed for the first time, and demonstrate that the in vivo consequences of these genetic variations should not be extrapolated from one substrate of these enzymes to another.

Microsampling in pediatric studies: pharmacokinetic sampling for baricitinib (Olumiant™) in global pediatric studies.

Background: Managing blood volumes in pediatric studies is challenging and should be minimized where possible. Results: A sensitive liquid chromatography with tandem mass spectrometry (LC-MS/MS) method was validated and implemented across two phase III global pediatric trials. Two 10-µl aliquots of blood were collected at each time point using the Mitra® device. Concordance between plasma and dried blood was established from older pediatric patients. Incurred sample reanalysis was performed in both studies using the second Mitra tip and acceptance was greater than 83%. Conclusion: The use of microsampling to generate pharmacokinetic data in 2-18-year-old pediatric patients was successfully implemented. Positive feedback was received from clinical sites about the microsampling technique assisting with enrollment of pediatric patients.

Quantification of abemaciclib and metabolites: evolution of bioanalytical methods supporting a novel oncolytic agent.

Aim: Bioanalytical methods undergo many revisions and modifications throughout drug development to meet the objectives of the study and development program. Results: Validated LC-MS/MS methodology used to quantify abemaciclib and four metabolites in human plasma is described. The method, initially validated to support the first-in-human study, was successfully modified to include additional metabolites as in vitro and in vivo information about the activity and abundance of human metabolites became available. Consistent performance of the method over time was demonstrated by an incurred sample reanalysis passing rate exceeding 95%, across clinical studies. An overview of the numerous methods involved during the development of abemaciclib, including the quantification of drugs evaluated as combination regimens and used as substrates during drug-drug interaction studies, is presented. Conclusion: Robust bioanalytical methods need to be designed with the flexibility required to support the evolving study objectives associated with registration and post-registration trials.

Lessons learned from the COVID-19 pandemic and its impact on bioanalysis and drug development.

The COVID-19 pandemic challenged pharmaceutical and bioanalytical communities at large, in the development of vaccines and therapeutics as well as supporting ongoing drug development efforts. Existing processes were challenged to manage loss of staffing at facilities along with added workloads for COVID-19-related study support including conducting preclinical testing, initiating clinical trials, conducting bioanalysis and interactions with regulatory agencies, all in an ultra-rapid timeframes. A key factor of success was creative rethinking of processes and removing barriers - some of which hitherto had been considered immovable. This article describes how bioanalysis was crippled at the onset of the pandemic but how innovative and highly collaborative efforts across teams within and outside of both pharma, bioanalytical labs and regulatory agencies worked together remarkably well.

Quantification of gemcitabine incorporation into human DNA by LC/MS/MS as a surrogate measure for target engagement.

In this study, we report a method for direct determination of gemcitabine incorporation into human DNA. Gemcitabine (dFdC), a structural analog of the nucleoside deoxycytidine (dC), derives its primary antitumor activity through interruption of DNA synthesis. Unlike other surrogate measures, DNA incorporation provides a mechanistic end point useful for dose optimization. DNA samples (ca. 25 microg) were hydrolyzed using a two-step enzymatic procedure to release dFdC which was subsequently quantified by LC-ESI-MS/MS using stable isotope labeled internal standards and selected reaction monitoring (SRM). dFdC was quantitated and reported relative to deoxyguanosine (dG) since dG is the complementary base for both dFdC and dC. The SRM channel for dG was detuned using collision energy as the attenuating parameter in order to accommodate the difference in relative abundance for these two analytes (>104) and enable simultaneous quantification from the same injection. The assay was shown to be independent of the amount of DNA analyzed. The method was validated for clinical use using a 3 day procedure assessing precision, accuracy, stability, selectivity, and robustness. The validated ranges for dFdC and dG were 5-7500 pg/mL and 0.1-150 microg/mL, respectively. Results are presented which confirm that the ratio of dFdC to dG in DNA isolated from tumor cells incubated with dFdC increases with increased exposure to the drug and that dFdC can also be quantified from DNA extracted from blood.

Evaluation of correlation between bioanalytical methods.

Bioanalytical methods evolve throughout clinical development timelines, resulting in the need for establishing equivalency or correlation between different methods to enable comparison of data across different studies. This is accomplished by the conduct of cross validations and correlative studies to compare and describe the relationship. The incurred sample reanalysis acceptance criterion seems to be adopted universally for cross validations and correlative studies; however, this does not identify any trends or biases between the two methods (datasets) being compared. Presented here are graphing approaches suitable for comparing two methods and describing equivalence or correlation. This article aims to generate awareness on graphing techniques that can be adopted during cross validations and correlative studies.

Land O'Lakes Workshop on Microsampling: Enabling Broader Adoption.

The microsampling workshop generated recommendations pertaining to blood sampling site (venous blood versus capillary blood), when to conduct a bridging study, statistical approaches to establish correlation/concordance and deciding on sample size, opportunities and challenges with patient-centric sampling, and how microsampling technology can enrich clinical drug development. Overall, the goal was to provide clarity and recommendations and enable the broader adoption of microsampling supporting patients' needs, convenience, and the transformation from clinic-centric to patient-centric drug development. The need and adoption of away-from-clinic sampling techniques has become critical to maintain patient safety during the current COVID-19 pandemic.

Microsampling: considerations for its use in pharmaceutical drug discovery and development.

There is growing interest in the implementation of microsampling approaches for the quantitation of circulating concentrations of analytes in biological samples derived from nonclinical and clinical studies involved in drug development. This interest is partly due to the ethical advantages of taking smaller blood volumes, particularly for studies in rodents, children and the critically ill. In addition, these technologies facilitate sampling to be performed in previously intractable locations and occasions. Further, they enable the collection of samples for additional purposes (extra time points, biomarkers, sampling during a clinical event, etc). This article gives a comprehensive insight to the utilization of these approaches in drug discovery and development, and provides recommendations for best practice for nonclinical, clinical and bioanalytical aspects.

A decade of incurred sample reanalysis: failures, investigations and impact.

Incurred sample reanalysis (ISR) is used to ensure the validity and reliability of bioanalytical data. Additionally, ISR results also help identify issues that could influence or bias the data. Overall, based on a decade of experimental data generated at Eli Lilly and Company, ISR failures are few with less than 5% of ISR samples failing to meet acceptance criteria. In a majority of situations, the cause for ISR failures has been 'human-error.' However, there are examples where ISR has helped identify issues related to the stability of the analyte or the ruggedness of the method. As a strategy, it is beneficial to conduct ISR following the completion of a few sample runs, so any potential issues impacting the validity and reliability of the data can be identified and rectified early.

Incorporating dried blood spot LC-MS/MS analysis for clinical development of a novel oncolytic agent.

AIM: Design and execution of a dried blood spot (DBS-LC-MS/MS) assay for pharmacokinetic analyses in oncology patients. RESULTS & DISCUSSION: The methodology was validated to collect and store DBS samples from multiple clinical sites, and analyze blood with diverse hematocrit ranges (25-55) to match the potential patient population. Bridging data comparing DBS and plasma showed high degree of concordance with DBS:plasma ratios of 0.81, demonstrating no preferential uptake or association with cellular components of the blood. Pharmacokinetic analysis supporting clinical development was performed using 20 µl of blood collected as DBS. Incurred sample reanalysis showed high correlation. CONCLUSION: Successful validation of a DBS method and implementation in the clinic enabled pharmacokinetic analysis during the clinical development of a novel oncolytic agent in oncology patients.

A review of nanoelectrospray ionization applications for drug metabolism and pharmacokinetics.

Although traditionally reserved for proteomic analysis, nanoESI has found increased use for small molecule applications related to drug metabolism/pharmacokinetics (DMPK). NanoESI, which refers to ESI performed at flow rates in the range of 200 to 1000 nL/min using smaller diameter emitters (10 to 100 microm id), produces smaller droplets than conventional ESI resulting in more efficient ionization. Benefits include greater sensitivity, enhanced dynamic range, and a reduced competition for ionization. These advantages may now be harnessed largely due to the introduction of a commercial system for automated nanoESI infusion. This development in turn has allowed ADME (absorption, distribution, metabolism, and excretion) scientists to consider novel approaches to mass spectrometric analysis without direct LC interfacing. While it is freely acknowledged that nanoESI infusion is not likely to supplant LC-MS as the primary analytical platform for ADME, nanoESI infusion has been successfully applied to both quantitative (bioanalysis) and qualitative (metabolite identification) applications. This review summarizes published applications of this technology and offers a perspective on where it fits best into the DMPK laboratory.

Using dried blood spot sampling to improve data quality and reduce animal use in mouse pharmacokinetic studies.

Traditional pharmacokinetic analysis in nonclinical studies is based on the concentration of a test compound in plasma and requires approximately 100 to 200 µL blood collected per time point. However, the total blood volume of mice limits the number of samples that can be collected from an individual animal-often to a single collection per mouse-thus necessitating dosing multiple mice to generate a pharmacokinetic profile in a sparse-sampling design. Compared with traditional methods, dried blood spot (DBS) analysis requires smaller volumes of blood (15 to 20 µL), thus supporting serial blood sampling and the generation of a complete pharmacokinetic profile from a single mouse. Here we compare plasma-derived data with DBS-derived data, explain how to adopt DBS sampling to support discovery mouse studies, and describe how to generate pharmacokinetic and pharmacodynamic data from a single mouse. Executing novel study designs that use DBS enhances the ability to identify and streamline better drug candidates during drug discovery. Implementing DBS sampling can reduce the number of mice needed in a drug discovery program. In addition, the simplicity of DBS sampling and the smaller numbers of mice needed translate to decreased study costs. Overall, DBS sampling is consistent with 3Rs principles by achieving reductions in the number of animals used, decreased restraint-associated stress, improved data quality, direct comparison of interanimal variability, and the generation of multiple endpoints from a single study.