Kinetics of Trisulfide-to-Disulfide Conversion of Therapeutic IgG1 Monoclonal Antibodies Under Physiological Conditions: A Case Study of Casirivimab And Imdevimab

The percentage of trisulfide variants is a product quality metric that is monitored during the manufacture of monoclonal antibody (mAb)-based therapeutics. Results from earlier preclinical studies revealed that trisulfide linkages in mAbs are rapidly converted to disulfides in circulation. In this study, casirivimab and imdevimab, which are both IgG1 subclass mAbs that target the non-overlapping epitopes in SARS-CoV2 Spike protein, are used as models to study the kinetics of trisulfide-to-disulfide conversion in vivo in human circulation. To determine the percentage of trisulfide variants in systemic circulation immediately after intravenous injection, both mAbs were immunoprecipitated from serum samples collected from COVID-19 patients that received this cocktail antibody treatment as part of a first-in-human study. The immunoprecipitated mAbs were then digested under non-reducing conditions and evaluated by liquid-chromatography-mass spectrometry (LC-MS). Significant reductions in the percentages of trisulfide variants were observed in serum samples as early as 1 hr after completion of the intravenous infusion. A flow-through dialysis model designed to mimic the redox potential of blood revealed a plausible chemical mechanism for the rapid trisulfide-to-disulfide conversion of IgG1 subclass mAbs under physiological conditions.

Immunogenicity of Cemiplimab: Low Incidence of Antidrug Antibodies and Cut-Point Suitability Across Tumor Types

The immunogenicity of cemiplimab, a fully human immunoglobulin G4 monoclonal antibody directed against programmed cell death 1, was assessed in patients across multiple tumor types. The development of antidrug antibodies (ADAs) against cemiplimab was monitored using a validated bridging immunoassay. To identify ADA-positive samples in the assay, statistically determined cut points were established by analyzing baseline clinical study samples from a mixed population of different tumor types, and this validation cut point was used to assess immunogenicity in all subsequent studies. Regulatory guidance requires that ADA assay cut points be verified for appropriateness in different patient populations. Thus, for the cemiplimab ADA assay, we evaluated whether each new oncology population was comparable with the validation population used to set the cut point. Assay responses from 2393 individual serum samples from 8 different tumor types were compared with the validation population, using established statistical methods for cut-point determination and comparison, with no significant differences observed. Across tumor types, the immunogenicity of cemiplimab was low, with an overall treatment-emergent ADA incidence rate of 1.9% and 2.5% at intravenous dose regimens of 3 mg/kg every 2 weeks and 350 mg every 3 weeks, respectively. Moreover, no neutralizing antibodies to cemiplimab were detected in patients with ADA-positive samples, and there was no observed impact of cemiplimab ADAs on pharmacokinetics. Study-specific cut points may be required in some diseases, such as immune and inflammatory diseases; however, based on this analysis, in-study cut points are not required for each new oncology disease indication for cemiplimab.

2022 White Paper on Recent Issues in Bioanalysis: FDA Draft Guidance on Immunogenicity Information in Prescription Drug Labeling, LNP & Viral Vectors Therapeutics/Vaccines Immunogenicity, Prolongation Effect, ADA Affinity, Risk-based Approaches, NGS, qPCR, ddPCR Assays (Part 3 - Recommendations on Gene Therapy, Cell Therapy, Vaccines Immunogenicity & Technologies; Immunogenicity & Risk Assessment of Biotherapeutics and Novel Modalities; NAb Assays Integrated Approach)

The 2022 16th Workshop on Recent Issues in Bioanalysis (WRIB) took place in Atlanta, GA, USA on September 26-30, 2022. Over 1000 professionals representing pharma/biotech companies, CROs, and multiple regulatory agencies convened to actively discuss the most current topics of interest in bioanalysis. The 16th WRIB included 3 Main Workshops and 7 Specialized Workshops that together spanned 1 week in order to allow exhaustive and thorough coverage of all major issues in bioanalysis, biomarkers, immunogenicity, gene therapy, cell therapy and vaccines. Moreover, in-depth workshops on ICH M10 BMV final guideline (focused on this guideline training, interpretation, adoption and transition); mass spectrometry innovation (focused on novel technologies, novel modalities, and novel challenges); and flow cytometry bioanalysis (rising of the 3rd most common/important technology in bioanalytical labs) were the special features of the 16th edition. As in previous years, WRIB continued to gather a wide diversity of international, industry opinion leaders and regulatory authority experts working on both small and large molecules as well as gene, cell therapies and vaccines to facilitate sharing and discussions focused on improving quality, increasing regulatory compliance, and achieving scientific excellence on bioanalytical issues. This 2022 White Paper encompasses recommendations emerging from the extensive discussions held during the workshop and is aimed to provide the bioanalytical community with key information and practical solutions on topics and issues addressed, in an effort to enable advances in scientific excellence, improved quality and better regulatory compliance. Due to its length, the 2022 edition of this comprehensive White Paper has been divided into three parts for editorial reasons. This publication (Part 3) covers the recommendations on Gene Therapy, Cell therapy, Vaccines and Biotherapeutics Immunogenicity. Part 1 (Mass Spectrometry and ICH M10) and Part 2 (LBA, Biomarkers/CDx and Cytometry) are published in volume 15 of Bioanalysis, issues 16 and 15 (2023), respectively.

Statistical Approaches for Establishing Appropriate Immunogenicity Assay Cut Points: Impact of Sample Distribution, Sample Size, and Outlier Removal

The statistical assessments needed to establish anti-drug antibody (ADA) assay cut points (CPs) can be challenging for bioanalytical scientists. Poorly established CPs that are too high could potentially miss treatment emergent ADA or, when set too low, result in detection of responses that may have no clinical relevance. We evaluated 16 validation CP datasets generated with ADA assays at Regeneron's bioanalytical laboratory and compared results obtained from different CP calculation tools. We systematically evaluated the impact of various factors on CP determination including biological and analytical variability, number of samples for capturing biological variability, outlier removal methods, and the use of parametric vs. non-parametric CP determination. In every study, biological factors were the major component of assay response variability, far outweighing the contribution from analytical variability. Non-parametric CP estimations resulted in screening positivity in drug-naïve samples closer to the targeted rate (5%) and were less impacted by skewness. Outlier removal using the boxplot method with an interquartile range (IQR) factor of 3.0 resulted in screening positivity close to the 5% targeted rate when applied to entire drug-naïve dataset. In silico analysis of CPs calculated using different sample sizes showed that using larger numbers of individuals resulted in CP estimates closer to the CP of the entire population, indicating a larger sample size (~ 150) for CP determination better represents the diversity of the study population. Finally, simpler CP calculations, such as the boxplot method performed in Excel, resulted in CPs similar to those determined using complex methods, such as random-effects ANOVA.

Interference in a Neutralizing Antibody Assay for Odronextamab, a CD20xCD3 Bispecific mAb, from Prior Rituximab Therapy and Possible Mitigation Strategy

A cell-based assay was developed to detect neutralizing anti-drug antibodies (NAbs) against odronextamab, a CD20xCD3 bispecific monoclonal antibody (mAb) under investigation for treatment of CD20+ B cell malignancies. In this assay, odronextamab bridges between two cell types, CD20-expressing HEK293 cells and CD3-expressing Jurkat T cells that generate a luciferase signal upon CD3 clustering. Patient samples containing NAbs directed to either arm of the bispecific drug block the odronextamab bridge formation between the cell lines thus preventing the generation of the luciferase signal. We determined that other anti-CD20 therapeutics also block bridge formation, resulting in false-positive results. In patient samples from odronextamab clinical trials, approximately 30% of baseline samples had a strong false-positive NAb signal that correlated with the presence of prior rituximab (anti-CD20) therapy. We determined that rituximab interference can be minimized by the addition of anti-rituximab antibodies in the NAb assay. Understanding and mitigating the impact of prior biologic exposure is increasingly important for implementing a successful bioanalytical strategy to support clinical drug development, especially in the immuno-oncology field.

Graphical Abstract

Odronextamab neutralizing antibody assay, interference, and mitigation. A Design of the odronextamab neutralizing antibody (NAb) assay where anti-CD20xCD3 drug bridges between CD20-expressing HEK293 cells and Jurkat T cells expressing an NFAT response element and luciferase reporter. True NAb prevents odronextamab from bridging between target and effector cells, thus preventing the expression of luciferase. B Interference with odronextamab from other anti-CD20 therapeutic antibodies (e.g., rituximab) from prior disease treatment generates a false-positive NAb result. Assay interference can be mitigated with an anti-idiotypic antibody against the interfering therapy.

Pre-existing Reactivity to an IgG4 Fc-Epitope: Characterization and Mitigation of Interference in a Bridging Anti-drug Antibody Assay

Twenty percent of baseline patient samples exhibited a pre-existing response in a bridging anti-drug antibody (ADA) assay for a human IgG4 monoclonal antibody (mAb) therapeutic. In some cases, assay signals were more than 100-fold higher than background, potentially confounding detection of true treatment-emergent ADA responses. The pre-existing reactivity was mapped by competitive inhibition experiments using recombinant proteins or chimeric human mAbs with IgG4 heavy chain regions swapped for IgG1 sequences. These experiments demonstrated that the majority of the samples had reactivity to an epitope containing leucine 445 in the CH3 domain of human IgG4. The pre-existing reactivity in baseline patient samples was mitigated by replacing the ADA assay capture reagent with a version of the drug containing a wild type IgG1 proline substitution at residue 445 without impacting detection of drug-specific, treatment-emergent ADA. Finally, purification on Protein G or anti-human IgG (H + L) columns indicated the pre-existing response was likely due to immunoglobulins in patient samples.

Graphical abstract

Bioanalytical Challenges due to Prior Checkpoint Inhibitor Exposure: Interference and Mitigation in Drug Concentration and Immunogenicity Assays

Monoclonal antibodies (mAbs) are a leading class of biotherapeutics. In oncology, patients often fail on early lines of biologic therapy to a specific target. Some patients may then enroll in a new clinical trial with a mAb specific for the same target. Therefore, immunoassays designed to quantify the current mAb therapy or assess immunogenicity to the drug may be susceptible to cross-reactivity or interference with residual prior biologics. The impact of two approved anti-PD-1 mAbs, pembrolizumab and nivolumab, was tested in several immunoassays for cemiplimab, another approved anti-PD-1 mAb. The methods included a target-capture drug concentration assay, a bridging anti-drug antibody (ADA) assay and a competitive ligand-binding neutralizing antibody (NAb) assay. We also tested bioanalytical strategies to mitigate cross-reactivity or interference in these assays from other anti-PD-1 biologics. Both pembrolizumab and nivolumab cross-reacted in the cemiplimab drug concentration assay. This was mitigated by addition of antibodies specific to pembrolizumab or nivolumab. ADA specific for pembrolizumab and nivolumab did not interfere in the cemiplimab ADA assay. However, pembrolizumab and nivolumab generated a false-positive response in a target-capture NAb assay. Our results demonstrate that similar exogenous pre-existing anti-PD-1 mAbs (biotherapeutics) such as pembrolizumab and nivolumab are detected and accurately quantified in the cemiplimab drug concentration assay. However, once steady state is achieved for the new therapy, prior biologics would likely not be detected. Cross-reactivity and interference in immunoassays from previous treatment with class-specific biotherapeutic(s) pose significant bioanalytical challenges, especially in immuno-oncology.

Liquid Chromatography-Multiple Reaction Monitoring-Mass Spectrometry Assay for Quantitative Measurement of Therapeutic Antibody Cocktail REGEN-COV Concentrations in COVID-19 Patient Serum

REGEN-COV is a cocktail of two human IgG1 monoclonal antibodies (REGN10933 + REGN10987) that targets severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein and has shown great promise to reduce the SARS-CoV-2 viral load in COVID-19 patients enrolled in clinical studies. A liquid chromatography-multiple reaction monitoring-mass spectrometry (LC-MRM-MS)-based method, combined with trypsin and rAspN dual enzymatic digestion, was developed for the determination of total REGN10933 and total REGN10987 concentrations in several hundreds of pharmacokinetic (PK) serum samples from COVID-19 patients participating in phase I, II, and III clinical studies. The performance characteristics of this bioanalytical assay were evaluated with respect to linearity, accuracy, precision, selectivity, specificity, and analyte stability before and after enzymatic digestion. The developed LC-MRM-MS assay has a dynamic range from 10 to 2000 μg/mL antibody drug in the human serum matrix, which was able to cover the serum drug concentration from day 0 to day 28 after drug administration in two-dose groups for the clinical PK study of REGEN-COV. The concentrations of REGEN-COV in the two-dose groups measured by the LC-MRM-MS assay were comparable to the concentrations measured by a fully validated electrochemiluminescence (ECL) immunoassay.

Simple and Sensitive Method for Deep Profiling of Host Cell Proteins in Therapeutic Antibodies by Combining Ultra-Low Trypsin Concentration Digestion, Long Chromatographic Gradients, and BoxCar Mass Spectrometry Acquisition

Liquid chromatography coupled to mass spectrometry (LC-MS) is a powerful tool for the analysis of host cell proteins (HCP) during antibody drug process development due to its sensitivity, selectivity, and adaptability. However, the enormous dynamic range between the therapeutic antibody and accompanying HCPs poses a significant challenge for LC-MS based detection of these low abundance impurities. To address this challenge, enrichment of HCPs via immunoaffinity, protein A, 2D-LC, or other strategies is typically performed. However, these enrichments are time-consuming and sometimes require a large quantity of sample. Here, we report a simple and sensitive strategy to analyze HCPs in therapeutic antibody samples without cumbersome enrichment by combining an ultra-low trypsin concentration during digestion under nondenaturing conditions, a long chromatographic gradient, and BoxCar acquisition (ULTLB) on a quadrupole-Orbitrap mass spectrometer. Application of this strategy to the NIST monoclonal antibody standard (NISTmAb) resulted in the identification of 453 mouse HCPs, which is a significant increase in the number of identified HCPs without enrichment compared to previous reports. Known amounts of HCPs were spiked into the purified antibody drug substance, demonstrating that the method sensitivity is as low as 0.5 ppm. Thus, the ULTLB method represents a sensitive and simple platform for deep profiling of HCPs in antibodies.

An apparatus for the continuous measurement of thickness during the electropolishing of superconducting cavities

An apparatus allowing continuous acquisition of thickness measurements during electropolishing of superconducting cavities is described. The instrument is based on the ultrasound thickness measurement technique and allows the connection of up to six probes. The apparatus has been employed to monitor the surface treatment of PIP-II low beta single cell prototypes developed and manufactured by LASA-INFN and specifically to measure surface removal at different points of interest on the cavity surface. The apparatus facilitated the development and optimization of electropolishing parameters for incorporation into the cavity manufacturing process.

Isotyping and Semi-Quantitation of Monkey Anti-Drug Antibodies by Immunocapture Liquid Chromatography-Mass Spectrometry

There is an urgent demand to develop new technologies to characterize immunogenicity to biotherapeutics. Here, we developed an immunocapture LC-MS assay to isotype and semi-quantify monkey anti-drug antibodies (ADAs) to fully human monoclonal antibody (mAb) drugs. ADAs were isolated from serum samples using an immunocapture step with the Fab of the full-length mAb cross-linked to magnetic beads to minimize matrix interference. A positive monoclonal antibody control against the human immunoglobulin kappa light chain was used as a calibration standard for ADA quantitation. The final LC-MS method contains 17 multiple reaction monitoring (MRM) transitions and an optimized 15-min LC method. The results suggested that IgG1 was the most abundant isotype in ADA-positive samples. IgG2 and IgG4 were identified at lower levels, whereas IgG3 and IgA levels were only observed at very minor levels. In addition, levels of total ADA measured by the LC-MS assay were comparable to results obtained using a traditional ligand binding assay (LBA). The LC-MS ADA assay enabled rapid immunogenicity assessment with additional isotype information that LBAs cannot provide.

Immunogenicity of Sarilumab Monotherapy in Patients with Rheumatoid Arthritis Who Were Inadequate Responders or Intolerant to Disease-Modifying Antirheumatic Drugs

Introduction

This open-label study evaluated the immunogenicity, safety, and efficacy of sarilumab monotherapy in patients with active, moderate-to-severe rheumatoid arthritis (RA) and inadequate response or intolerance to prior conventional synthetic disease-modifying antirheumatic drugs.

Methods

Adults with RA (n = 132) were randomized to receive subcutaneous sarilumab (150 [n = 65] or 200 mg [n = 67]) every 2 weeks (q2w) for 24 weeks. Endpoints included incidence of antidrug antibodies (ADAs) at week 24, safety, and efficacy.

Results

Persistent ADAs occurred in eight patients (12.3%) receiving sarilumab 150 mg q2w, seven of whom (10.8%) had neutralizing antibodies (NAbs), and in four patients (6.1%) receiving sarilumab 200 mg q2w, two of whom (3.0%) had NAbs; all exhibited low antibody titers. Infections and neutropenia were the most common adverse events (AEs). There were three serious AEs, no reports of anaphylaxis, and few hypersensitivity reactions (e.g., rash) with no notable differences in hypersensitivity reactions in ADA-positive patients relative to ADA-negative patients. Changes in absolute neutrophil count, alanine aminotransferase level, and platelet count were consistent with interleukin-6 signaling blockade and in agreement with previous observations. At week 24, overall American College of Rheumatology 20%/50%/70% improvement criteria responses were 73.8%/53.8%/29.2%, respectively, with sarilumab 150 mg q2w and 71.6%/50.7%/29.9% with sarilumab 200 mg q2w. No patients with an ADA-positive response showed loss of efficacy.

Conclusions

ADA titers were low and persistent ADAs and NAbs occurred relatively infrequently in both sarilumab dose groups. ADA did not meaningfully impact the safety or efficacy of either dose of sarilumab over 24 weeks.

Trial Registration

ClinicalTrials.gov, identifier NCT02121210.

Funding

Sanofi Genzyme and Regeneron Pharmaceuticals, Inc.

Plain Language Summary

Plain language summary available for this article.

Electronic Supplementary Material

The online version of this article (10.1007/s40744-019-0157-3) contains supplementary material, which is available to authorized users.

Systemic pharmacokinetic/pharmacodynamic analysis of intravitreal aflibercept injection in patients with retinal diseases

Objective

Explore relationships between systemic exposure to intravitreal aflibercept injection (IAI) and systemic pharmacodynamic effects via post hoc analyses of clinical trials of IAI for neovascular age-related macular degeneration (nAMD) or diabetic macular oedema (DME).

Methods and analysis

Adults from VGFT-OD-0702.PK (n=6), VGFT-OD-0512 (n= 5), VIEW 2 (n=1204) and VIVID-DME (n=404) studies were included. Validated ELISAs were used to measure concentrations of free and bound aflibercept (reported as adjusted bound) in plasma at predefined time points in each study. Non-compartmental analysis of concentration-time data was obtained with dense sampling in VGFT-OD-0702.PK and VGFT-OD-0512. Sparse sampling was used in VIEW 2 and VIVID-DME. Blood pressure or intrarenal function changes were also investigated.

Results

Following intravitreal administration, free aflibercept plasma concentrations quickly decreased once maximum concentrations were achieved at 1-3 days postdose; pharmacologically inactive adjusted bound aflibercept concentrations increased over a longer period and reached plateau 7 days postdose. Ratios of free and adjusted bound aflibercept decreased over time. There were no meaningful changes in systolic/diastolic blood pressure over the duration of each study at all systemic aflibercept exposure levels. For all treatment arms in VIEW 2, there was no clinically relevant change in mean intrarenal function from baseline at week 52. Overall, incidence of systemic adverse events in VIEW 2 and VIVID-DME was low and consistent with the known safety profile of IAI.

Conclusion

IAI administration was not associated with systemic effects in patients with nAMD or DME as measured by blood pressure or intrarenal function, two known pharmacologically relevant effects of anti-vascular endothelial growth factor.

Shewanella algae infection in Italy: report of 3 years' evaluation along the coast of the northern Adriatic Sea

Shewanella algae are Gram-negative, nonfermentative, motile bacilli, classified in the genus Shewanella in 1985. These environmental bacteria are occasionally identified in human infections, with a relatively strong association with exposure to seawater during warm seasons. This report describes a case series of 17 patients with infection correlated to S. algae in the coastal area of Romagna, Italy, from 2013 to 2016. The types of infection included otitis, pneumonia, sepsis and soft tissue (wound). Exposure to the marine environment during hot months was confirmed in 12 of 17 patients. An apparent correlation between increased severity of infection and patient age was also observed.

First report of sepsis due to Catabacter hongkongensis in an Italian patient

The first isolation of Catabacter hongkongensis in Italy is reported. Pleomorphic Gram-positive rods were grown in blood cultures from samples obtained from a 55-year-old patient admitted to the intensive care unit with sepsis after he experienced massive thoracic and abdominal trauma. The identification was obtained by amplification and sequencing of the 16S rRNA gene.

PSA Level 2 – An optimized methodology

A methodology for a Level 2 PSA is described that provides a more efficient structure than the two methods recommended in the German Leitfaden. This is accomplished by merging the top events for the system and accident management functions from the Level 2 space, referred to as the containment system event tree (CSET) as a direct extension of the Level 1 model and by introducing the containment phenomenological event tree (CPET) to represent only the phenomenological Level 2 top events. The interface between the Level 1+ CSET and the CPET is defined as the plant damage states (PDS) with the focused objective to minimize the effects of sequence to sequence variability on the CPET failure fractions. A clear and consequent distinction is made between the statistically random events modeled in the Level 1+ CSET and the deterministic physical processes with large state of knowledge uncertainties modeled in the CPET. It is shown that as a logical consequence the resulting CPET failure fractions are numbers and not distributions, and these numbers are consistent with the interpretation as the degree of confidence probabilities for the outcome of uncertain physical processes. While both methods recommended in the Leitfaden will yield correct results if properly applied, the proposed method will result in a more streamlined model that will be easier to trace, understand and review, and it will result in lower release category uncertainties by minimizing the sequence to sequence variability through the elimination of the intermediate pinch points and through the focused use of the PDS.

Psychological profiles derived by cluster analysis of Minnesota Multiphasic Personality Inventory and long term clinical outcome after coronary artery by pass grafting

BACKGROUND

To evaluate the psychological characteristics of coronary heart disease (CHD) patients after coronary artery bypass grafting (CABG) by cluster analysis of Minnesota Multiphasic Personality Inventory (MMPI-2) questionnaires and to assess the impact of the profiles obtained on long-term outcome.

METHODS

229 CHD patients admitted to cardiac rehabilitation filled in self-administered MMPI-2 questionnaires early after CABG. We assessed the relation between MMPI-2 profiles derived by cluster analysis, clinical characteristics and outcome at 3-year follow-up.

RESULTS

Among the 215 patients (76% men, median age 66 years) with valid criteria in control scales, we identified 3 clusters (G) with homogenous psychological characteristics: G1 patients (N = 75) presented somatoform complaints but overall minimal psychological distress. G2 patients (N=72) presented type D personality traits. G3 subjects (N=68) showed a trend to cynicism, mild increases in anger, social introversion and hostility. Clusters overlapped for clinical characteristics such as smoking (G1 21%, G2 24%, G3 24%, p ns), previous myocardial infarction (G1 43%, G2 47%, G3 49% p ns), LV ejection fraction (G1 60 [51-60]; G2 58 [49-60]; G3 60 [55-60], p ns), 3-vessel-disease prevalence (G1 69%, G2 65%, G3 71%, p ns). Three-year event rates were comparable (G1 15%; G2 18%; G3 15%) and Kaplan-Meier curves overlapped among clusters (p ns).

CONCLUSIONS

After CABG, the interpretation of MMPI-2 by cluster analysis is useful for the psychological and personological diagnosis to direct psychological assistance. Conversely, results from cluster analysis of MMPI-2 do not seem helpful to the clinician to predict long term outcome.

The long-term prognosis of renal transplant in patients with systemic vasculitis

Little information is available about the long-term outcome of renal transplantation in patients with systemic vasculitis (SV). We compared the outcomes of 19 renal transplant recipients with SV with those of 38 controls matched for time of transplantation, age, gender and source of donor. The mean post-transplant follow-up was 58 +/- 57 months for vasculitic patients and 61 +/- 49 months for controls. The actuarial 10-year patient survival was 87% in vasculitic patients and 90% in controls, death-censored graft survival were 84% and 100%, respectively. The risks of acute and chronic rejection, and arterial hypertension were not significantly different between the two groups. Infection was significantly more frequent in vasculitic patients (74% vs. 34%; p = 0.01). Seven patients (36.8%) had a recurrence of vasculitis in mean 45 months after renal transplant (0.076/patients/year). After recurrence, one patient had an irreversible humoral rejection, another died from hemophagocytosis and another restarted dialysis 1 year later. Long-term patient and renal allograft survival in vasculitic patients was good. Although graft function recovered in most relapsers after reinforcement of immunosuppression, one patient died and two lost graft function.

Benzyl amide-ketoacid inhibitors of HIV-integrase

Integrase is one of three enzymes expressed by HIV and represents a validated target for therapy. Previous reports have demonstrated that the diketoacid-based chemotype is a useful starting point for the design of inhibitors of this enzyme. In this study, one of the ketone groups is replaced by a benzylamide resulting in a new potent chemotype. A preliminary SAR study is carried out to investigate the substitution requirements on the phenyl ring and methylene group of the benzylamide.

Exploration of the diketoacid integrase inhibitor chemotype leading to the discovery of the anilide-ketoacids chemotype

Integrase is one of three enzymes expressed by HIV and represents a validated target for therapy. A previous study of the diketoacid-based chemotype suggested that there are two aryl-binding domains on integrase. In this study, modifications to the indole-based diketoacid chemotype are explored. It is demonstrated that the indole group can be replaced with secondary but not tertiary (e.g., N-methyl) aniline-based amides without sacrificing in vitro inhibitory activity. The difference in activity between the secondary and tertiary amides is most likely due to the opposite conformational preferences of the amide bonds, s-trans for the secondary-amide and s-cis for the tertiary-amide. However, it was found that the conformational preference of the tertiary amide can be reversed by incorporating the amide nitrogen atom into an indoline heterocycle, resulting in very potent integrase inhibitors.

Triketoacid inhibitors of HIV-integrase: A new chemotype useful for probing the integrase pharmacophore

Integrase is one of three enzymes expressed by HIV and represents a validated target for therapy. This study reports on the discovery of a new triketoacid-based chemotype that selectively inhibits the strand transfer reaction of HIV-integrase. SAR studies showed that the template binds to integrase in a manner similar to the diketoacid-based inhibitors. Moreover, comparison of the new chemotype to two different diketoacid templates led us to propose two aryl-binding domains in the inhibitor binding site. This information was used to design a new diketoacid template with improved activity against the enzyme.

Atorvastatin increases HDL cholesterol in hypercholesterolemic patients. Evidence of a relationship with baseline HDL cholesterol

BACKGROUND AND AIM

It has been reported that atorvastatin increases high-density lipoprotein cholesterol (HDL-C) more in patients with low than in those with high baseline HDL-C levels. This may have a biological explanation, but also suggests a statistical artifact known as the regression to the mean.

METHODS AND RESULTS

Atorvastatin 10 mg/day led to a 4% increase in HDL-C after two months in 67/121 patients with hypercholesterolemia (55%), who had lower baseline HDL-C levels than the patients in whom HDL-C did not increase. In the patients with baseline HDL-C below the median, HDL-C significantly increased whereas no change was observed in patients with baseline HDL-C above the median. The correlation coefficient between pre- and post-treatment HDL-C was 0.84, thus suggesting a regression to the mean. However, the regression artifact did not entirely explain the increase in HDL-C in patients with low baseline HDL-C or the lack of an increase in those with high baseline HDL-C. The adjusted mean increase was 5.4% in patients with low pretreatment HDL-C, and 2.4% in the patients with high pretreatment HDL-C. Multiple regression analysis with the changes in HDL-C as the dependent variable showed that baseline HDL-C and the changes in serum triglycerides independently contributed to the change in HDL-C levels.

CONCLUSIONS

Atorvastatin 10 mg/day increases HDL-C more in patients with low pretreatment HDL-C levels, an effect that seems to be related to the hypotriglyceridemic activity of the drug.

An approach to the identification of potent inhibitors of influenza virus fusion using parallel synthesis methodology

Structure-activity studies associated with the salicylic acid-derived inhibitor of influenza fusion, BMY-27709, were examined using a parallel synthesis approach. This SAR survey led to the discovery of potent influenza inhibitory activity in a series of aromatic amides and thioamides derived from 1,3,3-trimethyl-5-hydroxycyclohexylmethylamine. Select compounds were characterized as inhibitors of the H1 subtype of influenza A viruses that act by preventing the pH-induced fusion process, thereby blocking viral entry into host cells. In a plaque-reduction assay, the most potent inhibitors displayed EC(50) values of 0.02-0.14 microg/mL.

Effects of low doses of simvastatin and atorvastatin on high-density lipoprotein cholesterol levels in patients with hypercholesterolemia

BACKGROUND

Simvastatin 40 to 80 mg/d has been found to increase high-density lipoprotein cholesterol (HDL-C) levels significantly more than atorvastatin at equipotent doses (ie, 20-80 mg/d). Data on the effects of lower doses of the 2 drugs on HDL-C levels are conflicting.

OBJECTIVE

The purpose of this study was to investigate the effects of simvastatin 20 mg/d and atorvastatin 10 mg/d on HDL-C levels in patients with hypercholesterolemia.

METHODS

Patients with primary hypercholesterolemia (total cholesterol [TC] >250 mg/dL) who were not taking any lipid-lowering agents and who were following a low-fat diet were randomized to receive 1 of 2 treatments: simvastatin 20 mg/d or atorvastatin 10 mg/d. Serum TC, triglycerides (TG), low-density lipoprotein cholesterol (LDL-C), and HDL-C levels were measured using standard methods after 2 months of therapy. In a secondary analysis, lipids and lipoprotein cholesterol were measured after 1 year in patients who continued treatment.

RESULTS

Of the 240 patients enrolled (108 men and 132 women; age range, 23-77 years, mean [SEM] 56.7 [0.69]), 235 completed the study. After 2 months of therapy, TC, LDL-C, and serum TG levels decreased significantly versus baseline in both groups (P < 0.001), with no significant differences between treatment groups. HDL-C levels increased by 9.0% (P < 0.001 vs baseline) in the simvastatin group and by 4.3% (P < 0.02) in the atorvastatin group. The difference between the 2 groups in the percentage increase in HDL-C was statistically significant (P < 0.05). In 113 patients who continued treatment, HDL-C levels at 1 year were still significantly higher than baseline levels in the simvastatin group (6.3%, P = 0.034), but not in the atorvastatin group (2.8%, P = 0.587).

CONCLUSIONS

The findings from this study suggest that the HDL-C-increasing effect of simvastatin 20 mg is significantly greater than that of atorvastatin 10 mg. Since increasing HDL-C levels is thought to lower the risk for atherosclerosis and coronary heart disease, these results warrant further investigation.

Salicylamide inhibitors of influenza virus fusion

Structural variation of the quinolizidine heterocycle of the influenza fusion inhibitor BMY-27709 was examined by several topological dissections in order to illuminate the critical features of the ring system. This exercise resulted in the identification of a series of synthetically more accessible decahydroquinolines that retained the structural elements of BMY-27709 important for antiviral activity. The 2-methyl-cis-decahydroquinoline 6f was the most potent influenza inhibitor identified that demonstrated an EC50 of 90 ng/mL in a plaque reduction assay.

Lowering effects of four different statins on serum triglyceride level

OBJECTIVES

The main effect of statins is the decrease of serum level of low-density lipoprotein (LDL) cholesterol, due to the inhibition of intracellular cholesterol biosynthesis which brings about an upregulation of LDL receptors. A minor effect is the decrease of serum triglycerides. The present study was undertaken to verify whether all statins are effective in reducing serum triglycerides and whether their effect on triglycerides is related to the LDL cholesterol lowering activity.

METHODS

Of 197 hypercholesterolaemic patients on stable low-fat low-cholesterol diet, 49 were put on atorvastatin 10 mg per day, 48 on fluvastatin 40 mg per day, 50 on pravastatin 20 mg per day and 50 on simvastatin 10 mg per day.

RESULTS

After 2 months, mean percentage change in serum triglycerides and LDL cholesterol resulted to be significantly different among the four treatment groups, whereas the ratio between the percentage decrease in serum triglycerides and that of LDL cholesterol (Deltatriglyceride/DeltaLDL cholesterol ratio) was not significantly different. Only baseline serum triglycerides resulted to be significantly associated with Deltatriglycerides/DeltaLDL cholesterol ratio. All statins are then effective in decreasing triglyceride levels.

CONCLUSION

The lack of a significant difference in Deltatriglycerides/DeltaLDL cholesterol ratio among the treatment groups suggests that the more effective the statin is in decreasing LDL cholesterol, the more it will also be in decreasing serum triglycerides.

Identification of a 3 kb Alu-mediated BRCA1 gene rearrangement in two breast/ovarian cancer families

Most of the hereditary breast cancers are attributed to constitutive alterations of either BRCA1 or BRCA2 genes; nonetheless, germline mutations of these genes in 'high risk' families are found less frequently than expected from linkage data. Recent findings suggest that major genomic rearrangements of the BRCA1 gene might account for at least some of the apparently mutation negative cases. We studied 60 affected probands belonging to families with a strong history of breast and/or ovarian cancer who scored negative for BRCA1 gene mutations by PTT and SSCP analysis. DNA was analysed by the Southern blotting procedure using three different restriction enzymes, and two probes obtained by RT-PCR of the 5' and 3' BRCA1 coding sequence. A 3 kb deletion encompassing exon 17 and causing a frameshift mutation was identified in two independently ascertained families. RT-PCR and long-range DNA PCR were employed to characterize the rearrangement that was finally shown to be the result of a recombination between two very similar Alu repeats. This type of mutation is not identified by the conventional methods of mutation detection which are based on PCR amplification of single exons. Therefore, further search for gene rearrangements is needed to better define the proportion of 'high risk' families that might be explained by gross genomic alterations of the BRCA1 gene.

Elevated urinary norepinephrine in interstitial cystitis

OBJECTIVES

To measure urinary catecholamines and determine the extent to which they may be elevated in urine from patients with interstitial cystitis (IC).

METHODS

Random urine samples from patients with IC (n = 111) and urine from normal volunteers (n = 92) were acidified on collection (voided and catheterized specimens) and assayed for catecholamine (norepinephrine or normetanephrine) by enzyme-linked immunosorbent assay. Creatinine levels in these urine samples were also measured.

RESULTS

Analysis of the data indicated that patients with IC had a higher urinary level of the neurotransmitter norepinephrine compared with the measured levels in the urine of normal volunteers (89.1 +/- 58.3 versus 54.9 +/- 37.1 microg/g creatinine, P <0.05). The metabolite normetanephrine was similar in the urine samples from these two groups. Urine from patients with bladder outlet obstruction (n = 11) did not have elevated amounts of urinary norepinephrine. The norepinephrine levels were not statistically different in the urine samples from patients with symptomatic and asymptomatic IC. The elevated urinary levels in patients with IC did not decrease after treatment with sodium pentosanpolysulfate (Elmiron), heparinoids, dimethyl sulfoxide, or combinations of these during 1 to 15 months of treatment.

CONCLUSIONS

Norepinephrine was found to be elevated in the urine from patients with IC compared with urine from normal controls. This would be consistent with increased sympathetic (adrenergic) activity from the bladders of patients with IC or possibly from increased adrenal activity, since stress is associated with symptom increase in some patients with IC. Norepinephrine levels did not decrease with treatment nor did they differ between symptomatic and asymptomatic patients at the time of urine collection.

Accuracy of calculated serum low-density lipoprotein cholesterol for the assessment of coronary heart disease risk in NIDDM patients

OBJECTIVE

To evaluate the accuracy of LDL cholesterol calculated with Friedewald's equation in the assessment of cardiovascular risk in NIDDM patients.

RESEARCH DESIGN AND METHODS

The calculation of LDL cholesterol according to Friedewald's formula was compared with the measurement of LDL cholesterol separated by ultracentrifugation in 151 NIDDM patients with fairly good metabolic control (HbA1c < or =10%) and in 405 nondiabetic subjects.

RESULTS

Measured and calculated LDL cholesterol was found to be well correlated in both diabetic (r = 0.95) and nondiabetic (r = 0.97) subjects. Compared with measured LDL cholesterol, the calculated LDL cholesterol differed by > or =10% in 34% of samples from diabetic patients and in 26% of samples from nondiabetic subjects (chi(2) = 3.885, P < 0.05). The percentage of error increased when the serum triglyceride (TG) level was > or =200 mg/dl (2.26 mmol/l) and when the ratio of VLDL cholesterol to TG was <0.20 or >0.29 in both groups of subjects. Although the percentage of error from calculated LDL cholesterol was greater in diabetic than in nondiabetic subjects because of the greater prevalence of hypertriglyceridemia in the former group, the misclassification of coronary heart disease risk, according to the cutoff points of the National Cholesterol Education Program (NCEP), was similar in the two groups (25% in diabetic and 22% in nondiabetic subjects). In both groups of patients, the misclassification of coronary heart disease risk was higher when calculation of LDL cholesterol produced values near the cutoff points.

CONCLUSIONS

Although accuracy in the estimation of LDL cholesterol is less than ideal, Friedewald's equation seems to be of value in the correct assignment of coronary heart disease risk classes in the great majority of diabetic as well as nondiabetic subjects. Caution must be exercised for subjects in whom calculated LDL cholesterol is close to the cutoff points of the NCEP guidelines.

Biodistribution of indocyanine green in a porcine burn model: light and fluorescence microscopy

BACKGROUND

Infrared-excited fluorescence of intravenously administered indocyanine green (ICG) is being used as a method of early determination of burn depth.

METHODS

Fluorescence microscopy and tissue fluorescence were recorded in a porcine burn model and correlated to burn severity and age.

RESULTS

Recently placed superficial burns show significant fluorescence compared with adjacent normal tissue as a result of a strong inflammatory reaction in the superficial dermis with minimal vascular occlusion. The magnitude of the inflammatory reaction decreases with time. For deeper burns, vascular occlusion prevents transport of ICG into the burn and the intensity of ICG fluorescence in burn eschar is negligible.

CONCLUSION

The intensity of ICG fluorescence measured at the surface of the wound for burns of similar age was shown to decrease exponentially with the depth of the burn. The enhanced fluorescence of partial-thickness burns is attributable to increased permeability, and the decreased signal associated with deeper injuries is attributable to vascular occlusion. These results suggest that it is possible to differentiate burns that will heal spontaneously with minimal granulation from those that will not by measuring the intensity of ICG fluorescence.

Association of alcohol consumption with HDL subpopulations defined by apolipoprotein A-I and apolipoprotein A-II content

OBJECTIVE

To investigate the relationship between alcohol intake and serum level of high-density lipoprotein (HDL) subfractions defined on the basis of their apolipoprotein A-I and A-II content (LpA-I and LpA-I: A-II).

DESIGN

Observational study.

SETTING

Institute of Internal Medicine and Medical Physiopathology, IRCCS Maggiore Hospital, University of Milan.

SUBJECTS

One hundred healthy males with a mean age of 42 +/- 11.1 y, selected among blood donors.

RESULTS

Both LpA-I and LpA-I:A-II were significantly higher in men drinking more than 30 g a day of alcohol than in non-drinkers (LpA-I: difference between means 6.5 mg/dL, 95% C.I. 1.14-11.9; LpA-I:A-II difference between means 11.5 mg/dL, 95% C.I. 0.52-22.5). The association of alcohol consumption with LpA-I and LpA-I:A-II levels was independent from age, body mass index, physical activity, serum triglycerides and diet composition.

CONCLUSIONS

Alcohol consumption is associated with an increase of serum levels of both LpA-I and LpA-I:A-II particles and this may, at least in part, explain the reduced cardiovascular morbidity observed in subjects drinking moderate amounts of alcoholic beverages.

SPONSORSHIP

Supported by grants from Ricerca Corrente Ospedale Maggiore di Milano IRCCS, Milan Italy.

Molecular mechanism underlying the action of a novel fusion inhibitor of influenza A virus

In the initial stages of influenza virus infection, the hemagglutinin (HA) protein of influenza virus mediates both adsorption and penetration of the virus into the host cell. Recently, we identified and characterized BMY-27709 as an inhibitor of the H1 and H2 subtypes of influenza A virus that specifically inhibits the HA function necessary for virus-cell membrane fusion (G.-X. Luo, R. Colonno, and M. Krystal, Virology 226:66-76, 1996). Studies presented herein show that the inhibition is mediated through specific interaction with the HA protein. This binding represses the low-pH-induced conformational change of the HA protein which is a prerequisite for membrane fusion. In an attempt to define the binding pocket within the HA molecule, a number of drug-resistant viruses have been isolated and characterized. Sequence analyses of the HA gene of these drug-resistant viruses mapped amino acid changes responsible for drug resistance to a region located near the amino terminus of HA2. In addition, we have identified inactive analogs of BMY-27709 which are able to compete out the inhibitory activity of BMY-27709. This finding suggests that inhibition of the HA-mediated membrane fusion by this class of compounds is not solely the result of binding within the HA molecule but requires specific interactions.