https://escholarship.org/content/qt6xw5b20t/qt6xw5b20t.pdf?t=qeu451

Targeted Peptide Measurements in Biology and Medicine: Best Practices for Mass Spectrometry-based Assay Development Using a Fit-for-Purpose Approach

Biochemical markers have a central position in the diagnosis and management of patients in clinical medicine, and also in clinical research and drug development, also for brain disorders, such as Alzheimer's disease. The enzyme-linked immunosorbent assay (ELISA) is frequently used for measurement of low-abundance biomarkers. However, the quality of ELISA methods varies, which may introduce both systematic and random errors. This urges the need for more rigorous control of assay performance, regardless of its use in a research setting, in clinical routine, or drug development. The aim of a method validation is to present objective evidence that a method fulfills the requirements for its intended use. Although much has been published on which parameters to investigate in a method validation, less is available on a detailed level on how to perform the corresponding experiments. To remedy this, standard operating procedures (SOPs) with step-by-step instructions for a number of different validation parameters is included in the present work together with a validation report template, which allow for a well-ordered presentation of the results. Even though the SOPs were developed with the intended use for immunochemical methods and to be used for multicenter evaluations, most of them are generic and can be used for other technologies as well.

/pdf/a-practical-guide-to-immunoassay-method-validation-52wet853mr.pdf

A Practical Guide to Immunoassay Method Validation

A sensitive and specific LC-MS/MS method for rapid diagnosis of Niemann-Pick C1 disease from human plasma

BACKGROUND: Protein cancer biomarkers serve multiple clinical purposes, both early and late, during disease progression. The search for new and better biomarkers has become an integral component of contemporary cancer research. However, the number of new biomarkers cleared by the US Food and Drug Administration has declined substantially over the last 10 years, raising concerns regarding the efficiency of the biomarker-development pipeline.

CONTENT: We describe different clinical uses of cancer biomarkers and their performance requirements. We also present examples of protein cancer biomarkers currently in clinical use and their limitations. The major barriers that candidate biomarkers need to overcome to reach the clinic are addressed. Finally, the long and arduous journey of a protein cancer biomarker from the bench to the clinic is outlined with an example.

SUMMARY: The journey of a protein biomarker from the bench to the clinic is long and challenging. Every step needs to be meticulously planned and executed to succeed. The history of clinically useful biomarkers suggests that at least a decade is required for the transition of a marker from the bench to the bedside. Therefore, it may be too early to expect that the new technological advances will catalyze the anticipated biomarker revolution any time soon.

/pdf/the-long-journey-of-cancer-biomarkers-from-the-bench-to-the-5fzsd24znz.pdf

The Long Journey of Cancer Biomarkers from the Bench to the Clinic

Oral enzalutamide (160 mg once daily) is approved for the treatment of metastatic castration-resistant prostate cancer (mCRPC). This article describes the pharmacokinetics of enzalutamide and its active metabolite N-desmethyl enzalutamide. Results are reported from five clinical studies. In a dose-escalation study (n = 140), enzalutamide half-life was 5.8 days, steady state was achieved by day 28, accumulation was 8.3-fold, exposure was approximately dose proportional from 30–360 mg/day, and intersubject variability was ≤30 %. In a mass balance study (n = 6), enzalutamide was primarily eliminated by hepatic metabolism. Renal excretion was an insignificant elimination pathway for enzalutamide and N-desmethyl enzalutamide. In a food-effect study (n = 60), food did not have a meaningful effect on area under the plasma concentration–time curve (AUC) of enzalutamide or N-desmethyl enzalutamide, and in an hepatic impairment study, AUC of the sum of enzalutamide plus N-desmethyl enzalutamide was similar in men with mild (n = 6) or moderate (n = 8) impairment (Child–Pugh Class A and B) versus men with normal hepatic function (n = 14). In a phase III trial, an exposure-response analysis of steady-state predose (trough) concentrations (C
 trough) versus overall survival (n = 1103) showed that active treatment C
 trough quartiles for 160 mg/day were uniformly beneficial relative to placebo, and no threshold of C
 trough was associated with a statistically significant better response. Enzalutamide has predictable pharmacokinetics, with low intersubject variability. Similar efficacy was observed in patients across the concentration/exposure range associated with a fixed oral dose of enzalutamide 160 mg/day.

/pdf/clinical-pharmacokinetic-studies-of-enzalutamide-36l1oxs7bv.pdf

Clinical Pharmacokinetic Studies of Enzalutamide

A syntetic discussion on bioanalytical methods vali dation is presented from the point of view of regul atory documents, scientific articles and books. The validation parameters are described, together with an example of validation methodology applied in the case of ch romatographic methods used in bioanalysis, taking i n account to the recent Food and Drug Administration (FDA) gu idelines and documents of the International Confere nce on Harmonisation of Technical Requirements for Registr ation of Pharmaceuticals for Human Use (ICH).

Jurgen Burhenne

Papers

Bioanalytical Method Validation