2015 White Paper on recent issues in bioanalysis: focus on new technologies and biomarkers (Part 2 - hybrid LBA/LCMS and input from regulatory agencies).

The 2015 9th Workshop on Recent Issues in Bioanalysis (9th WRIB) took place in Miami, Florida with participation of over 600 professionals from pharmaceutical and biopharmaceutical companies, biotechnology companies, contract research organizations and regulatory agencies worldwide. It is once again a 5-day week long event - a full immersion bioanalytical week - specifically designed to facilitate sharing, reviewing, discussing and agreeing on approaches to address the most current issues of interest in bioanalysis. The topics covered included both small and large molecules, and involved LCMS, hybrid LBA/LCMS, LBA approaches including the focus on biomarkers and immunogenicity. This 2015 White Paper encompasses recommendations that emerged from the extensive discussions held during the workshop, and is aimed at providing the bioanalytical community with key information and practical solutions on topics and issues addressed, in an effort to advance scientific excellence, improve quality and deliver better regulatory compliance. Due to its length, the 2015 edition of this comprehensive White Paper has been divided into three parts. Part 2 covers the recommendations for hybrid LBA/LCMS and regulatory agencies' inputs. Part 1 (small molecule bioanalysis using LCMS) and Part 3 (large molecule bioanalysis using LBA, biomarkers and immunogenicity) will be published in volume 7 of Bioanalysis, issues 22 and 24, 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).

Discovery of tricyclic 5,6-dihydro-1H-pyridin-2-ones as novel, potent, and orally bioavailable inhibitors of HCV NS5B polymerase.

A novel series of non-nucleoside small molecules containing a tricyclic dihydropyridinone structural motif was identified as potent HCV NS5B polymerase inhibitors. Driven by structure-based design and building on our previous efforts in related series of molecules, we undertook extensive SAR studies, in which we identified a number of metabolically stable and very potent compounds in genotype 1a and 1b replicon assays. This work culminated in the discovery of several inhibitors, which combined potent in vitro antiviral activity against both 1a and 1b genotypes, metabolic stability, good oral bioavailability, and high C(12) (PO)/EC(50) ratios.

5,5'- and 6,6'-dialkyl-5,6-dihydro-1H-pyridin-2-ones as potent inhibitors of HCV NS5B polymerase.

The discovery of 5,5'- and 6,6'-dialkyl-5,6-dihydro-1H-pyridin-2-ones as potent inhibitors of the HCV RNA-dependent RNA polymerase (NS5B) is described. Several of these agents also display potent antiviral activity in cell culture experiments (EC50 <0.10 microM). In vitro DMPK data for selected compounds as well as crystal structures of representative inhibitors complexed with the NS5B protein are also disclosed.

5,6-Dihydro-1H-pyridin-2-ones as potent inhibitors of HCV NS5B polymerase.

5,6-Dihydro-1H-pyridin-2-one analogs were discovered as a novel class of inhibitors of genotype 1 HCV NS5B polymerase. Among these, compound 4ad displayed potent inhibitory activities in biochemical and replicon assays (IC(50) (1b)<10nM; IC(50) (1a)<25nM, EC(50) (1b)=16nM), good in vitro DMPK properties, as well as moderate oral bioavailability in monkeys (F=24%).

Novel HCV NS5B polymerase inhibitors derived from 4-(1',1'-dioxo-1',4'-dihydro-1'lambda(6)-benzo[1',2',4']thiadiazin-3'-yl)-5-hydroxy-2H-pyridazin-3-ones. Part 5: Exploration of pyridazinones containing 6-amino-substituents.

The synthesis of 4-(1',1'-dioxo-1',4'-dihydro-1'lambda(6)-benzo[1',2',4']thiadiazin-3'-yl)-5-hydroxy-2H-pyridazin-3-ones bearing 6-amino substituents as potent inhibitors of the HCV RNA-dependent RNA polymerase (NS5B) is described. Several of these agents also display potent antiviral activity in cell culture experiments (EC(50)<0.10 microM). In vitro DMPK data (microsome t(1/2), Caco-2 P(app)) for many of the compounds are also disclosed, and a crystal structure of a representative inhibitor complexed with the NS5B protein is discussed.

Hexahydro-pyrrolo- and hexahydro-1H-pyrido[1,2-b]pyridazin-2-ones as potent inhibitors of HCV NS5B polymerase.

Hexahydro-pyrrolo- and hexahydro-1H-pyrido[1,2-b]pyridazin-2-one analogs were discovered as a novel class of inhibitors of genotype 1 HCV NS5B polymerase. Among these, compound 4c displayed potent inhibitory activities in biochemical and replicon assays (IC(50) (1b) <10 nM; EC(50) (1b)=34 nM) as well as good stability towards human liver microsomes (HLM t(1/2) =59 min).

4-(1,1-Dioxo-1,4-dihydro-1lambda6-benzo[1,4]thiazin-3-yl)-5-hydroxy-2H-pyridazin-3-ones as potent inhibitors of HCV NS5B polymerase.

4-(1,1-Dioxo-1,4-dihydro-1lambda(6)-benzo[1,4]thiazin-3-yl)-5-hydroxy-2H-pyridazin-3-one analogs were discovered as a novel class of inhibitors of HCV NS5B polymerase. Structure-based design led to the identification of compound 3a that displayed potent inhibitory activities in biochemical and replicon assays (1b IC(50)<10 nM; 1b EC(50)=1.1 nM) as well as good stability toward human liver microsomes (HLM t(1/2)>60 min).

Structure-based design, synthesis, and biological evaluation of 1,1-dioxoisothiazole and benzo[b]thiophene-1,1-dioxide derivatives as novel inhibitors of hepatitis C virus NS5B polymerase.

A novel series of HCV NS5B polymerase inhibitors comprising 1,1-dioxoisothiazoles and benzo[b]thiophene-1,1-dioxides were designed, synthesized, and evaluated. SAR studies guided by structure-based design led to the identification of a number of potent NS5B inhibitors with nanomolar IC(50) values. The most potent compound exhibited IC(50) less than 10nM against the genotype 1b HCV polymerase and EC(50) of 70 nM against a genotype 1b replicon in cell culture. The DMPK properties of selected compounds were also evaluated.

Pyrrolo[1,2-b]pyridazin-2-ones as potent inhibitors of HCV NS5B polymerase.

Pyrrolo[1,2-b]pyridazin-2-one analogs were discovered as a novel class of inhibitors of genotype 1 HCV NS5B polymerase. Structure-based design led to the discovery of compound 3 k, which displayed potent inhibitory activities in biochemical and replicon assays (IC(50) (1b)<10nM; EC(50) (1b)=12 nM) as well as good stability towards human liver microsomes (HLM t(1/2)>60 min).

Novel HCV NS5B polymerase inhibitors derived from 4-(1',1'-dioxo-1',4'-dihydro-1'lambda(6)-benzo[1',2',4']thiadiazin-3'-yl)-5-hydroxy-2H-pyridazin-3-ones. Part 3: Further optimization of the 2-, 6-, and 7'-substituents and initial pharmacokinetic assessments.

5-Hydroxy-3(2H)-pyridazinone derivatives were investigated as inhibitors of genotype 1 HCV NS5B polymerase. Lead optimization led to the discovery of compound 3a, which displayed potent inhibitory activities in biochemical and replicon assays [IC(50) (1b)<10nM; IC(50) (1a)=22 nM; EC(50) (1b)=5nM], good stability toward human liver microsomes (HLM t(1/2)>60 min), and high ratios of liver to plasma concentrations 12h after a single oral administration to rats.

Novel HCV NS5B polymerase inhibitors derived from 4-(1',1'-dioxo-1',4'-dihydro-1'lambda6-benzo[1',2',4']thiadiazin-3'-yl)-5-hydroxy-2H-pyridazin-3-ones: Part 4. Optimization of DMPK properties.

5-Hydroxy-3(2H)-pyridazinone derivatives were investigated as potent inhibitors of genotype 1 HCV NS5B polymerase focusing on the optimization of their drug metabolism and pharmacokinetics (DMPK) profiles. This investigation led to the discovery of potent inhibitors with improved DMPK properties.

Novel HCV NS5B polymerase inhibitors derived from 4-(1',1'-dioxo-1',4'-dihydro-1'lambda6-benzo[1',2',4']thiadiazin-3'-yl)-5-hydroxy-2H-pyridazin-3-ones. Part 1: exploration of 7'-substitution of benzothiadiazine.

5-Hydroxy-3(2H)-pyridazinone derivatives were investigated as inhibitors of genotype 1 HCV NS5B polymerase. The synthesis, structure-activity relationships (SAR), metabolic stability, and structure-based design approach for this new class of compounds are discussed.