Toward Accurate and Robust Liquid Chromatography-Mass Spectrometry-Based Quantification of Antibody Biotherapeutics in Tissues.

Liquid chromatography-mass spectrometry (LC-MS) affords a highly promising solution for absolute quantification of biotherapeutics/targets in tissues, which is critical for drug development. Nonetheless, accurate/robust tissue quantification remains challenging largely owing to the lack of optimal approaches to address the following fundamental prerequisites: (i) efficient removal of residual blood without losing tissue-associated biotherapeutics; (ii) an optimal method to exhaustively/quantitatively recover target proteins from tissues; and (iii) an appropriate strategy to prepare calibration/quality-control samples to ensure accurate tissue analysis. Here, we devised novel analytical procedures enabling extensive and systematic investigation of the above issues and thereby development of optimal strategies for accurate tissue analysis. Key discoveries include: first, using a novel procedure of sequential administration of nonlabeled and then stable-isotope-labeled monoclonal antibody (mAb); it was determined that perfusion with three blood volumes of heparinized saline is optimal, achieving efficient blood removal (95-99%) and low quantitative bias (0.5-13%); second, a reference sample set established by mass-balanced, exhaustive extraction, permitted accurate measurement of absolute protein recovery from tissues of dosed animals; with this method, we found mAb biotherapeutics present in free-(49.3-75.4%) and bound-forms (24.6-50.7%) in tissues, even without a target; therefore, a denaturing detergent buffer is necessary for exhaustive extraction (recovery>90%); third, overnight-incubation of calibration samples after spiking mAb to tissue was found to improve quantitative accuracy, especially for nondenaturing buffer extraction. These investigations established the critical parameters and optimal protocols that can be universally applied to achieve accurate and robust quantification of biotherapeutics/targets in tissues. As a proof of concept, we conducted the first-ever extensive pharmacokinetics measurement of mAb in major tissues with a LC-MS-based method, where interesting features of mAb tissue disposition were observed.

Clinical application of volumetric absorptive microsampling to the gefapixant development program.

In this paper we show the application of the Tasso OnDemand™, a novel automated sample collection device, in conjunction with volumetric absorptive microsampling (VAMS) for the development of gefapixant, a P2X3 receptor antagonist currently under clinical development for the treatment of refractory and unexplained chronic cough and endometriosis-related pain. A LC-MS/MS bioanalytical method was developed and validated using VAMS to support this development program. This method was utilized in a drug-drug interaction study to establish a mathematical bridging relationship with data obtained from a validated plasma assay used to support the program. The VAMS bioanalytical method and the predictability of the mathematical relationship is reported and discussed here.

Entrectinib, a TRK/ROS1 inhibitor with anti-CNS tumor activity: differentiation from other inhibitors in its class due to weak interaction with P-glycoprotein.

BACKGROUND: Studies evaluating the CNS penetration of a novel tyrosine kinase inhibitor, entrectinib, proved challenging, particularly due to discrepancies across earlier experiments regarding P-glycoprotein (P-gp) interaction and brain distribution. To address this question, we used a novel "apical efflux ratio" (AP-ER) model to assess P-gp interaction with entrectinib, crizotinib, and larotrectinib, and compared their brain-penetration properties. METHODS: AP-ER was designed to calculate P-gp interaction with the 3 drugs in vitro using P-gp-overexpressing cells. Brain penetration was studied in rat plasma, brain, and cerebrospinal fluid (CSF) samples after intravenous drug infusion. Unbound brain concentrations were estimated through kinetic lipid membrane binding assays and ex vivo experiments, while the antitumor activity of entrectinib was evaluated in a clinically relevant setting using an intracranial tumor mouse model. RESULTS: Entrectinib showed lower AP-ER (1.1-1.15) than crizotinib and larotrectinib (≥2.8). Despite not reaching steady-state brain exposures in rats after 6 hours, entrectinib presented a more favorable CSF-to-unbound concentration in plasma (CSF/Cu,p) ratio (>0.2) than crizotinib and larotrectinib at steady state (both: CSF/Cu,p ~0.03). In vivo experiments validated the AP-ER approach. Entrectinib treatment resulted in strong tumor inhibition and full survival benefit in the intracranial tumor model at clinically relevant systemic exposures. CONCLUSIONS: Entrectinib, unlike crizotinib and larotrectinib, is a weak P-gp substrate that can sustain CNS exposure based on our novel in vitro and in vivo experiments. This is consistent with the observed preclinical and clinical efficacy of entrectinib in neurotrophic tropomyosin receptor kinase (NTRK) and ROS1 fusion-positive CNS tumors and secondary CNS metastases.

AAPS Workshop Report on ICH M10.

Over the last decade, several regulatory guidelines on bioanalytical method validation (BMV) have been issued by regulatory agencies around the world. This has left the bioanalytical community struggling with regional differences in regulatory expectations when preparing for global pharmaceutical submissions. The International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use (ICH) has the mission to achieve greater harmonization worldwide to ensure that safe, effective, and high-quality medicines are developed and registered in the most resource-efficient manner. Following calls for harmonization, ICH-selected bioanalytical method validation and sample analysis among its topics for guidance development and earlier this year released a draft guideline (M10) on BMV for public consultation. In response, the American Association of Pharmaceutical Scientists (AAPS) held a 3-day workshop to provide a forum for regulatory, industry, and academic scientists to discuss the guideline and hear various points of view on key aspects. While there was agreement that the draft guideline is generally well written and comprehensive, specific topics generated considerable discussion and, in some cases, revision recommendations for consideration by the expert working group (EWG) responsible for the guideline content. This report provides a summary of the workshop proceedings.

A single-center, open-label study investigating the excretion balance, pharmacokinetics, metabolism, and absolute bioavailability of a single oral dose of [14C]-labeled idasanutlin and an intravenous tracer dose of [13C]-labeled idasanutlin in a single cohort of patients with solid tumors.

PURPOSE: Idasanutlin, a selective small-molecule MDM2 antagonist in phase 3 testing for refractory/relapsed AML, is a non-genotoxic p53 activator with oral administration. To determine the need to conduct dedicated trial(s) for organ impairment on pharmacokinetic (PK) exposure and/or drug-drug interactions, a single dose of [14C]- and [13C]-labeled idasanutlin was evaluated. METHODS: This study was an open-label, non-randomized, single-center trial of idasanutlin to investigate the excretion balance, pharmacokinetics, metabolism, and absolute bioavailability of a single oral dose of [14C]-labeled idasanutlin and an IV tracer dose of [13C]-labeled idasanutlin in a single cohort of patients with solid tumors. After completing cycle 1 assessments, patients could have participated in an optional treatment extension of idasanutlin. Clinical endpoints were PK, and safety/tolerability. RESULTS: Co-administration of an oral dose of idasanutlin with an IV tracer dose revealed low systemic CL, a moderate Vd, and a moderate (40.1%) absolute bioavailability of idasanutlin. Idasanutlin and its major inactive metabolite, M4, were the major circulating moieties in plasma, and excretion of idasanutlin-associated radioactivity was primarily via the fecal route (91.5% of the dose), with negligible amounts recovered in urine, following oral administration. CONCLUSION: The clinical implications of this study support the conclusion that renal impairment is unlikely to significantly impact exposure to idasanutlin and M4 metabolite, whereas a significant hepatic impairment may potentially alter exposure to the parent drug and/or metabolite(s). The potential for drug-drug interactions is low.

High-Throughput, Sensitive LC-MS Quantification of Biotherapeutics and Biomarkers Using Antibody-Free, Peptide-Level, Multiple-Mechanism Enrichment via Strategic Regulation of pH and Ionic and Solvent Strengths.

Sensitive and high-throughput measurement of biotherapeutics and biomarkers in plasma and tissues is critical for protein-drug development. Enrichment of target signature peptide (SP) after sample digestion permits sensitive LC-MS-based protein quantification and carries several prominent advantages over protein-level enrichment; however, developing high-quality antipeptide antibodies is challenging. Here we describe a novel, antibody-free, peptide-level-enrichment technique enabling high-throughput, sensitive, and robust quantification of proteins in biomatrices, by highly selective removal of matrix peptides and components via cation-exchange (CX) reversed-phase (RP) SPE with strategically regulated pH and ionic and organic strengths. Multiple-mechanism washing and elution achieved highly selective separation despite the low plate number of the SPE cartridge. We first investigated the adsorption-desorption behaviors of peptides on CX-RP sorbent and the coexisting, perplexing effects of pH, and ionic and organic strengths on the selectivity for SP enrichment, which has not been previously characterized. We demonstrated that the selectivity for separating target SPs from matrix peptides was closely associated with buffer pH relative to the pI of the SP, and pH values of pI - 2, pI, and pI + 2 respectively provided exceptional specificity for the ionic wash, the hydrophobic wash, and selective elution. Furthermore, desorption of peptides from the mixed-mode sorbent showed exponential and linear dependence, respectively, on organic-solvent percentage and salt percentage. On the basis of these findings, we established a streamlined procedure for rapid and robust method development. Quantification of biotherapeutics, targets, and biomarkers in plasma and tissues was used as the model system. Selective enrichment of target SPs was achieved along with elimination of 87-95% of matrix peptides, which improved the LOQ by 20-fold (e.g., 2 ng per gram of tissue). Application was demonstrated by sensitive quantification of time courses of mAb (T84.66) and target (CEA) in plasma and tumor tissues from a low-dose mouse PK study. For the first time, down-regulation of membrane-associated antigen following mAb treatment was observed. The CX-RP enrichment is robust, high-throughput, and universally applicable and thus is highly valuable for ultrasensitive, large-scale measurement of target protein in plasma and tissues.

Effect of Hepatic Impairment on the Pharmacokinetics of Alectinib.

Alectinib is approved and recommended as the preferred first-line treatment for patients with anaplastic lymphoma kinase (ALK)-positive non-small cell lung cancer. The effect of hepatic impairment on the pharmacokinetics (PK) of alectinib was assessed with physiologically based PK modeling prospectively and in a clinical study. An open-label study (NCT02621047) investigated a single 300-mg dose of alectinib in moderate (n = 8) and severe (n = 8) hepatic impairment (Child-Pugh B/C), and healthy subjects (n = 12) matched for age, sex, and body weight. Physiologically based PK modeling was conducted prospectively to inform the clinical study design and support the use of a lower dose and extended PK sampling in the study. PK parameters were calculated for alectinib, its major similarly active metabolite, M4, and the combined exposure of alectinib and M4. Unbound concentrations were assessed at 6 and 12 hours postdose. Administration of alectinib to subjects with hepatic impairment increased the area under the plasma concentration-time curve from time 0 to infinity of the combined exposure of alectinib and M4 to 136% (90% confidence interval [CI], 94.7-196) and 176% (90%CI 98.4-315), for moderate and severe hepatic impairment, respectively, relative to matched healthy subjects. Unbound concentrations for alectinib and M4 did not appear substantially different between hepatic-impaired and healthy subjects. Moderate hepatic impairment had only a modest, not clinically significant effect on alectinib exposure, while the higher exposure observed in severe hepatic impairment supports a dose adjustment in this population.

Effects of posaconazole (a strong CYP3A4 inhibitor), two new tablet formulations, and food on the pharmacokinetics of idasanutlin, an MDM2 antagonist, in patients with advanced solid tumors.

PURPOSE: Idasanutlin, a selective small-molecule MDM2 antagonist in phase 3 testing for refractory/relapsed AML, is a non-genotoxic oral p53 activator. To optimize its dosing conditions, a number of clinical pharmacology characteristics were examined in this multi-center trial in patients with advanced solid tumors. METHOD: This was an open-label, single-dose, crossover clinical pharmacology study investigating the effects of strong CYP3A4 inhibition with posaconazole (Part 1), two new oral formulations (Part 2), as well as high-energy/high-fat and low-energy/low-fat meals (Part 3) on the relative bioavailability of idasanutlin. After completing Part 1, 2, or 3, patients could have participated in an optional treatment with idasanutlin. Clinical endpoints were pharmacokinetics (PK), pharmacodynamics (PD) of MIC-1 elevation (Part 1 only), and safety/tolerability. RESULTS: The administration of posaconazole 400 mg BID × 7 days with idasanutlin 800 mg resulted in a slight decrease (7%) in Cmax and a modest increase (31%) in AUC for idasanutlin, a marked reduction in Cmax (~ 60%) and AUC0 (~ 50%) for M4 metabolite, and a minimal increase (~ 24%) in serum MIC-1 levels. Cmax and AUC were both 45% higher for the SDP formulation. While the low-fat meal caused a less than 20% increase in all PK exposure parameters with the 90% CI values just outside the upper end of the equivalence criteria (80-125%), the high-fat meal reached bioequivalence with dosing under fasting. CONCLUSION: In patients with solid tumors, multiple doses of posaconazole, a strong CYP3A4 inhibitor, minimally affected idasanutlin PK and PD without clinical significance. The SDP formulation improved rBA/exposures by ~ 50% without major food effect.

Sensitive, High-Throughput, and Robust Trapping-Micro-LC-MS Strategy for the Quantification of Biomarkers and Antibody Biotherapeutics.

For LC-MS-based targeted quantification of biotherapeutics and biomarkers in clinical and pharmaceutical environments, high sensitivity, high throughput, and excellent robustness are all essential but remain challenging. For example, though nano-LC-MS has been employed to enhance analytical sensitivity, it falls short because of its low loading capacity, poor throughput, and low operational robustness. Furthermore, high chemical noise in protein bioanalysis typically limits the sensitivity. Here we describe a novel trapping-micro-LC-MS (T-µLC-MS) strategy for targeted protein bioanalysis, which achieves high sensitivity with exceptional robustness and high throughput. A rapid, high-capacity trapping of biological samples is followed by µLC-MS analysis; dynamic sample trapping and cleanup are performed using pH, column chemistry, and fluid mechanics separate from the µLC-MS analysis, enabling orthogonality, which contributes to the reduction of chemical noise and thus results in improved sensitivity. Typically, the selective-trapping and -delivery approach strategically removes >85% of the matrix peptides and detrimental components, markedly enhancing sensitivity, throughput, and operational robustness, and narrow-window-isolation selected-reaction monitoring further improves the signal-to-noise ratio. In addition, unique LC-hardware setups and flow approaches eliminate gradient shock and achieve effective peak compression, enabling highly sensitive analyses of plasma or tissue samples without band broadening. In this study, the quantification of 10 biotherapeutics and biomarkers in plasma and tissues was employed for method development. As observed, a significant sensitivity gain (up to 25-fold) compared with that of conventional LC-MS was achieved, although the average run time was only 8 min/sample. No appreciable peak deterioration or loss of sensitivity was observed after >1500 injections of tissue and plasma samples. The developed method enabled, for the first time, ultrasensitive LC-MS quantification of low levels of a monoclonal antibody and antigen in a tumor and cardiac troponin I in plasma after brief cardiac ischemia. This strategy is valuable when highly sensitive protein quantification in large sample sets is required, as is often the case in typical biomarker validation and pharmaceutical investigations of antibody therapeutics.

Investigating the effect of autoinduction in cynomolgus monkeys of a novel anticancer MDM2 antagonist, idasanutlin, and relevance to humans.

1. Idasanutlin (RG7388) is a potent p53-MDM2 antagonist currently in clinical development for treatment of cancer. The purpose of the present studies was to investigate the cause of marked decrease in plasma exposure after repeated oral administration of RG7388 in monkeys and whether the autoinduction observed in monkeys is relevant to humans. 2. In monkey liver and intestinal microsomes collected after repeated oral administration of RG7388 to monkeys, significantly increased activities of homologue CYP3A8 were observed (ex vivo). Investigation using a physiologically based pharmacokinetic (PBPK) model suggested that the loss of exposure was primarily due to induction of metabolism in the gut of monkeys. 3. Studies in monkey and human primary hepatocytes showed that CYP3A induction by RG7388 only occurred in monkey hepatocytes but not in human hepatocytes, which suggests the observed CYP3A induction is monkey specific. 4. The human PK data obtained from the first cohorts confirmed the lack of relevant induction as predicted by the human hepatocytes and the PBPK modelling based on no induction in humans.

Bioanalytical method validation considerations for LC-MS/MS assays of therapeutic proteins.

This paper highlights the recommendations of a group of industry scientists in validating regulated bioanalytical LC-MS/MS methods for protein therapeutics in a 2015 AAPSJ White Paper. This group recommends that most of the same precision and accuracy validation criteria used for ligand-binding assays (LBAs) be applied to LC-MS/MS-based assays where proteins are quantified using the LC-MS/MS signal from a surrogate peptide after proteolytic digestion (PrD-LCMS methods). PrD-LCMS methods are generally more complex than small molecule LC-MS/MS assays and may often include LBA procedures, leading to the recommendation for a combination of chromatographic and LBA validation strategies and appropriate acceptance criteria. Several key aspects of this bioanalytical approach that are discussed in the White Paper are treated here in additional detail. These topics include selectivity/specificity, matrix effect, digestion efficiency, stability and critical reagent considerations.

Recommendations for validation of LC-MS/MS bioanalytical methods for protein biotherapeutics.

This paper represents the consensus views of a cross-section of companies and organizations from the USA and Canada regarding the validation and application of liquid chromatography tandem mass spectrometry (LC-MS/MS) methods for bioanalysis of protein biotherapeutics in regulated studies. It was prepared under the auspices of the AAPS Bioanalytical Focus Group's Protein LC-MS Bioanalysis Subteam and is intended to serve as a guide to drive harmonization of best practices within the bioanalytical community and provide regulators with an overview of current industry thinking on applying LC-MS/MS technology for protein bioanalysis. For simplicity, the scope was limited to the most common current approach in which the protein is indirectly quantified using LC-MS/MS measurement of one or more of its surrogate peptide(s) produced by proteolytic digestion. Within this context, we considered a range of sample preparation approaches from simple in-matrix protein denaturation and digestion to complex procedures involving affinity capture enrichment. Consideration was given to the method validation experiments normally associated with traditional LC-MS/MS and ligand-binding assays. Our collective experience, thus far, is that LC-MS/MS methods for protein bioanalysis require different development and validation considerations than those used for small molecules. The method development and validation plans need to be tailored to the particular assay format being established, taking into account a number of important factors: the intended use of the assay, the test species or study population, the characteristics of the protein biotherapeutic and its similarity to endogenous proteins, potential interferences, as well as the nature, quality, and availability of reference and internal standard materials.

2014 White Paper on recent issues in bioanalysis: a full immersion in bioanalysis (Part 3 - LBA and immunogenicity).

The 2014 8th Workshop on Recent Issues in Bioanalysis (8th WRIB), a 5-day full immersion in the evolving field of bioanalysis, took place in Universal City, California, USA. Close to 500 professionals from pharmaceutical and biopharmaceutical companies, contract research organizations and regulatory agencies worldwide convened to share, review, discuss and agree on approaches to address current issues of interest in bioanalysis. The topics covered included both small and large molecules, and involved LCMS, hybrid LBA/LCMS, LBA approaches and immunogenicity. From the prolific discussions held during the workshop, specific recommendations are presented in this 2014 White Paper. As with the previous years' editions, this paper acts as a practical tool to help the bioanalytical community continue advances in scientific excellence, improved quality and better regulatory compliance. Due to its length, the 2014 edition of this comprehensive White Paper has been divided into three parts for editorial reasons. This publication (Part 3) covers the recommendations for Large molecules bioanalysis using LBA and Immunogenicity. Part 1 (Small molecules bioanalysis using LCMS) and Part 2 (Hybrid LBA/LCMS, Electronic Laboratory Notebook and Regulatory Agencies' Input) were published in the Bioanalysis issues 6(22) and 6(23), respectively.

2014 White Paper on recent issues in bioanalysis: a full immersion in bioanalysis (Part 2 - hybrid LBA/LCMS, ELN & regulatory agencies' input).

The 2014 8th Workshop on Recent Issues in Bioanalysis (8th WRIB), a 5-day full immersion in the evolving field of bioanalysis, took place in Universal City, California, USA. Close to 500 professionals from pharmaceutical and biopharmaceutical companies, contract research organizations and regulatory agencies worldwide convened to share, review, discuss and agree on approaches to address current issues of interest in bioanalysis. The topics covered included both small and large molecules, and involved LCMS, hybrid LBA/LCMS, LBA approaches and immunogenicity. From the prolific discussions held during the workshop, specific recommendations are presented in this 2014 White Paper. As with the previous years' editions, this paper acts as a practical tool to help the bioanalytical community continue advances in scientific excellence, improved quality and better regulatory compliance. Due to its length, the 2014 edition of this comprehensive White Paper has been divided into three parts for editorial reasons. This publication (Part 2) covers the recommendations for Hybrid LBA/LCMS, Electronic Laboratory Notebook and Regulatory Agencies' Input. Part 1 (Small molecules bioanalysis using LCMS) was published in the Bioanalysis issue 6(22) and Part 3 (Large molecules bioanalysis using LBA and Immunogenicity) will be published in the Bioanalysis issue 6(24).

2014 White Paper on recent issues in bioanalysis: a full immersion in bioanalysis (Part 1--small molecules by LCMS).

The 2014 8th Workshop on Recent Issues in Bioanalysis (8th WRIB), a 5-day full immersion in the evolving field of bioanalysis, took place in Universal City, California, USA. Close to 500 professionals from pharmaceutical and biopharmaceutical companies, contract research organizations and regulatory agencies worldwide convened to share, review, discuss and agree on approaches to address current issues of interest in bioanalysis. The topics covered included both small and large molecules, and involved LCMS, hybrid LBA/LCMS, LBA approaches and immunogenicity. From the prolific discussions held during the workshop, specific recommendations are presented in this 2014 White Paper. As with the previous years' editions, this paper acts as a practical tool to help the bioanalytical community continue advances in scientific excellence, improved quality and better regulatory compliance. Due to its length, the 2014 edition of this comprehensive White Paper has been divided into three parts for editorial reasons. This publication (Part 1) covers the recommendations for small molecule bioanalysis using LCMS. Part 2 (Hybrid LBA/LCMS, Electronic Laboratory Notebook and Regulatory Agencies' input) and Part 3 (Large molecules bioanalysis using LBA and Immunogenicity) will be published in the upcoming issues of Bioanalysis.