HPLC-MS/MS-based quantification of human monoclonal antibodies targeting SARS-CoV-2 in the presence of endogenous SARS-CoV-2 antibodies in human serum.

Antibodies for treatment and prophylaxis against SARS-CoV-2 are needed particularly for immunocompromised individuals, who cannot adequately benefit from vaccination. To address this need, Aerium Therapeutics is developing antibodies targeting the SARS-CoV-2 spike protein. A bioanalytical method to quantify fully human monoclonal antibodies in a population with widely varying anti-spike antibody titers is required to investigate the pharmacokinetics of these antibodies in clinical trials. To eliminate interference from endogenous anti-spike protein antibodies, an HPLC-MS/MS assay was developed to quantify the investigational monoclonal antibodies (AER001 and AER002) by targeting signature peptides spanning the monoclonal antibodies' CDR regions. By optimizing and comparing affinity capture and ammonium sulphate precipitation, it was demonstrated that both procedures allowed accurate and precise quantification of AER001 and AER002 in human serum with comparable sensitivity. Ammonium sulphate precipitation outperformed immunocapture due to its simplicity and speed at lower cost and a full bioanalytical method validation was performed in human serum. The assay was also validated for human nasal lining fluid extract with a 50-fold lower limit of quantification and was shown to deliver similar sensitivity to previously published affinity capture HPLC-MS/MS assays. Finally, the CDR-derived signature peptides were also generated by tryptic digestion of blank serum in some individuals, an important caveat for HPLC-MS/MS strategies targeting human monoclonal antibodies. In summary, the presented results show that ammonium sulphate precipitation and HPLC-MS/MS allow accurate and precise quantification of monoclonals in clinical studies. The developed methods demonstrate that HPLC-MS/MS can reliably quantify human monoclonal antibodies even when endogenous antibodies with overlapping specificities are present and are crucial for the clinical testing of two investigational COVID-19 monoclonals.

The Parasite Reduction Ratio (PRR) Assay Version 2: Standardized Assessment of Plasmodium falciparum Viability after Antimalarial Treatment In Vitro.

With artemisinin-resistant Plasmodium falciparum parasites emerging in Africa, the need for new antimalarial chemotypes is persistently high. The ideal pharmacodynamic parameters of a candidate drug are a rapid onset of action and a fast rate of parasite killing or clearance. To determine these parameters, it is essential to discriminate viable from nonviable parasites, which is complicated by the fact that viable parasites can be metabolically inactive, whilst dying parasites can still be metabolically active and morphologically unaffected. Standard growth inhibition assays, read out via microscopy or [3H] hypoxanthine incorporation, cannot reliably discriminate between viable and nonviable parasites. Conversely, the in vitro parasite reduction ratio (PRR) assay is able to measure viable parasites with high sensitivity. It provides valuable pharmacodynamic parameters, such as PRR, 99.9% parasite clearance time (PCT99.9%) and lag phase. Here we report the development of the PRR assay version 2 (V2), which comes with a shorter assay duration, optimized quality controls and an objective, automated analysis pipeline that systematically estimates PRR, PCT99.9% and lag time and returns meaningful secondary parameters such as the maximal killing rate of a drug (Emax) at the assayed concentration. These parameters can be fed directly into pharmacokinetic/pharmacodynamic models, hence aiding and standardizing lead selection, optimization, and dose prediction.

Blood schizontocidal and gametocytocidal activity of 3-hydroxy-N'-arylidenepropanehydrazonamides: a new class of antiplasmodial compounds.

3-Hydroxy-N'-arylidenepropanehydrazonamides represent a new class of antiplasmodial compounds. The two most active phenanthrene-based derivatives showed potent in vitro antiplasmodial activity against the 3D7 (sensitive) and Dd2 (multidrug-resistant) strains of Plasmodium falciparum with nanomolar IC50 values in the range of 8-28 nM. Further studies revealed that the most promising derivative, bearing a 4-fluorobenzylidene moiety, demonstrated in vivo antiplasmodial activity after oral administration in a P. berghei malaria model, although no complete parasite elimination was achieved with a four-dose regimen. The in vivo efficacy correlated well with the plasma concentration levels, and no acute toxicity symptoms (e.g., death or changes in general behavior or physiological activities) were observed, which is in agreement with a >1000-fold lower activity against L6 cells, a primary cell line derived from mammalian (rat) skeletal myoblasts. This indicates that lead compound 29 displays selective activity against P. falciparum. Moreover, both phenanthrene-based derivatives were active against stage IV/V gametocytes of P. falciparum in vitro.

The effect of hematocrit on bioanalysis of DBS: results from the EBF DBS-microsampling consortium.

BACKGROUND: The European Bioanalysis Forum dried blood spots (DBS)/microsampling consortium is reporting back from the experiments they performed on further documenting the potential hurdles of the DBS technology. This paper is focused on the impact of hematocrit changes on DBS analyses. RESULTS: The hematocrit can have an effect on the size of the blood spot, on spot homogeneity and on extraction recovery in a compound-dependent manner. The extraction recovery can change upon aging in an hematocrit-dependent way. Different card materials can give different outcomes. CONCLUSIONS: The results from the conducted experiments show that the issues of DBS in regulated bioanalysis are real and that the technology will need improvements to be ready for use as a general tool for regulated bioanalysis.

In-depth study of homogeneity in DBS using two different techniques: results from the EBF DBS-microsampling consortium.

BACKGROUND: At the start of their work, the European Bioanalysis Forum dried blood spots microsampling consortium did not form a dedicated team to investigate the spot homogeneity. However, two teams performed experiments that produced results relating to sample homogeneity. RESULTS: The data, which were produced via two different approaches (a radiolabeled and a nonradiolabeled approach), are highly complementary and demonstrate clear effects on sample inhomogeneity due to the substrate type, compound and hematocrit levels. CONCLUSION: The results demonstrate that sample inhomogeneity is a significant hurdle to the use of dried blood spots for regulated bioanalysis that should be investigated further in the method establishment phase if the whole spot is not sampled.

First-in-man safety and pharmacokinetics of synthetic ozonide OZ439 demonstrates an improved exposure profile relative to other peroxide antimalarials.

AIMS: To assess the safety and pharmacokinetics of a new synthetic ozonide antimalarial, OZ439, in a first-in-man, double-blind study in healthy volunteers. METHODS: OZ439 was administered as single oral daily doses of a capsule formulation (50-1200 mg) or an oral dispersion (400-1600 mg, fed and fasted states) and for up to 3 days as an oral dispersion (200-800 mg day(-1)). Plasma concentrations of OZ439 and its metabolites were measured by LC-MS. RESULTS: The pharmacokinetic (PK) profile of OZ439 was characterized by a t(max) of around 3 h, followed by a multiphasic profile with a terminal half-life of 25-30 h. The PK parameters were approximately dose proportional for each group and profiles of the metabolites followed a similar pattern to that of the parent compound. Following dosing for 3 days, accumulation was less than two-fold but steady-state was not achieved. In the presence of food, no effect was observed on the t(1/2) of OZ439 while the exposure was increased by 3 to 4.5-fold. Exposure was higher and inter-subject variability was reduced when OZ439 was administered as an oral dispersion compared with a capsule. The urinary clearance of OZ439 and its metabolites was found to be negligible and OZ439 did not induce CYP3A4. The antimalarial activity profiles of a subset of serum samples suggested that the major antimalarial activity originated from OZ439 rather than from any of the metabolites. CONCLUSION: The safety and pharmacokinetic profile of OZ439 merits progression to phase 2a proof of concept studies in the target population of acute uncomplicated malaria.

Determination of 6-keto prostaglandin F1α and its metabolites in human plasma by LC-MS/MS.

An HPLC-MS/MS method was developed and validated for the quantification of 6-keto prostaglandin F1α, the stable hydrolysis product of prostacyclin, and its metabolites 2,3-dinor-6-keto prostaglandin F1α and 6,15-diketo-13,14-dihydro prostaglandin F1α in human plasma. For sample preparation, a solid phase extraction step was combined with a column switching approach for analytes enrichment and further sample clean-up of the processed sample. The assay was validated in the concentration range 50.0-5000 pg/mL for 6-keto prostaglandin F1α and 6,15-diketo-13,14-dihydro prostaglandin F1α, and 100-10,000 pg/mL for 2,3-dinor-6-keto prostaglandin F1α. The inter-batch precision was better than 12.7%, 9.2%, and 9.4% for 6-keto prostaglandin F1α, 2,3-dinor-6-keto prostaglandin F1α, and 6,15-diketo-13,14-dihydro prostaglandin F1α, respectively. The inter-batch accuracy was between 97.3% and 100.8% for 6-keto prostaglandin F1α, between 97.5% and 103.0% for 2,3-dinor-6-keto prostaglandin F1α, and between 92.0% and 100.0% for 6,15-diketo-13,14-dihydro prostaglandin F1α. Further it has been demonstrated that the analytes were stable in plasma for 20 h at room temperature, during three freeze-and-thaw cycles, for 96 days at -25 °C storage temperature, and 50h in the autosampler tray at room temperature.

Workshop/conference report on EMA draft guideline on validation of bioanalytical methods.

This is a summary report of the workshop on the EMA Draft Guideline on Validation of Bioanalytical Methods held April 15-16th 2010 in Brussels (Belgium) and jointly organised by the European Bioanalysis Forum (EBF) and the European Federation for Pharmaceutical Sciences (EUFEPS). Aim of the workshop was to discuss the current scientific knowledge in the area of bioanalysis, the regulatory requirements with special focus on the new Draft Guideline and their subsequent implementation to the work in bioanalytical laboratories. Comments on the Draft Guideline were presented and discussed with representatives from regulatory authorities in Europe. The workshop started with discussions on the scope of the Guideline and the need for implementation of GLP. A special focus was set on method validation of chromatographic procedures and subsequent study sample analysis. In addition, requirements for ligand-binding assays were briefly addressed. Intention of this Conference Report is to summarise important aspects of the discussions in order to draw certain conclusions, and to identify points which remain open and may require clarification at a later stage.

Simultaneous determination of capecitabine and its metabolite 5-fluorouracil by column switching and liquid chromatographic/tandem mass spectrometry.

A liquid chromatographic/tandem mass spectrometric method was developed and validated for the quantitation of capecitabine and its metabolite 5-fluorouracil in human plasma. The simultaneous determination of both analytes was achieved by a column switching method using a trapping column and two analytical columns with different stationary phases. Isocratic elution was used for the separation of capecitabine on a C18 column whereas 5-fluorouracil was separated using gradient elution on an non-polar carbon phase. The calibration curves were linear for both compounds with a correlation factor (R2) > 0.9993 for 5-fluorouracil and >0.9942 for capecitabine. The assay was validated in the concentration range 5.00-1000 ng ml(-1) for both compounds. The intra-day precision was better than 10% for 5-fluorouracil and better than 11% for capecitabine whereas the inter-day precision was better than 8% for 5-fluorouracil and better than 14% for capecitabine.

Proteomics application exercise of the Swiss Proteomics Society: report of the SPS'02 session.

After the success of the mass spectrometry (MS) round table that was held at the first Swiss Proteomics Society congress (SPS'01) in Geneva, the SPS has organized a proteomics application exercise and allocated a full session at the SPS'02 congress. The main objective was to encourage the exchange of expertise in protein identification, with a focus on the use of mass spectrometry, and to create a bridge between the users' questions and the instrument providers' solutions. Two samples were sent to fifteen interested labs, including academic groups and MS hardware providers. Participants were asked to identify and partially characterize the samples. They consisted of a complex mixture of peptide/proteins (sample A) and an almost pure recombinant peptide carrying post-translational modifications (sample B). Sample A was an extract of snake venom from the species Bothrops jararaca. Sample B was a recombinant and modified peptide derived from the shrimp Penaeus vannamei penaeidin 3a. The eight labs that returned results reported the use of a wide range of MS instrumentation and techniques. They mentioned a variety of time and manpower allocations. The origin of sample A was generally identified together with a number of database protein entries. The difficulty of the sample identification lay in the incomplete knowledge of the Bothrops species genome sequence and is discussed. Sample B was generally and correctly identified as penaeidin. However, only one group reported the full primary structure. Interestingly, the approaches were again varied and are discussed in the text.

Coupling of a Nucleoside with DNA by a Methyltransferase.

How to outwit a methyltransferase: Methyltransferases (Mtases) catalyze the transfer of the activated methyl group from the cofactor S-adenosyl-L-methionine (1) to acceptors R within a large variety of biomolecules. Through the use of the cofactor analogue 2 a whole nucleoside was coupled to DNA in a Mtase-catalyzed reaction.