Plasma glucosylsphingosine correlations with baseline disease burden and response to eliglustat in two clinical trials of previously untreated adults with Gaucher disease type 1.

In Gaucher disease type 1 (GD1), accumulation of the lipid substrates glucosylceramide and glucosylsphingosine (lyso-GL-1 or lyso-Gb1), primarily in the spleen, liver, and bone marrow, leads to progressive hepatosplenomegaly, anemia, thrombocytopenia, and skeletal disease. Plasma glucosylceramide elevations are modest, variable, and normalize within weeks of starting treatment before clinical changes are evident, and therefore, have limited value for monitoring treatment responses. Serum chitotriosidase activity, a widely used GD biomarker, is also elevated in many other conditions but is not measurable in 5-10% of individuals due to a common CHIT1 null variant.

Criteria of slope and endogenous level for selection of matrix in the quantitation of endogenous compounds by LC-MS/MS.

Selection of the appropriate matrix for standard curve is critical for an accurate and sensitive biomarker method. Slope of a standard curve is the key factor for parallelism assessment between tested matrix and authentic matrix for LC-MS/MS assays. Here the authors have established slope criteria using a generic equation and endogenous level criteria for achieving assay sensitivity.

Pharmacokinetics, Pharmacodynamics, Safety, and Tolerability of Oral Venglustat in Healthy Volunteers.

Venglustat is a small-molecule glucosylceramide synthase (GCS) inhibitor designed to reduce the production of glucosylceramide (GL-1) and thus is expected to substantially reduce formation of glucosylceramide-based glycosphingolipids. Because of its effect on glycosphingolipid formation, GCS inhibition has therapeutic potential across many disorders affecting glycosphingolipid metabolism. Therefore, venglustat is under development for substrate reduction therapy in multiple diseases, including Gaucher disease type 3, Parkinson's disease associated with GBA mutations, Fabry disease, GM2 gangliosidosis, and autosomal dominant polycystic kidney disease.

Long-term efficacy of olipudase alfa in adults with acid sphingomyelinase deficiency (ASMD): Further clearance of hepatic sphingomyelin is associated with additional improvements in pro- and anti-atherogenic lipid profiles after 42 months of treatment.

The liver is a major site of lipoprotein synthesis and metabolism. Liver manifestations of chronic visceral ASMD include hepatomegaly, fibrosis, elevated liver enzymes and a pro-atherogenic lipid profile. Measurements of sphingomyelin (SM) levels in liver biopsies and lyso-SM in plasma were used as pharmacodynamic biomarkers.

Olipudase alfa for treatment of acid sphingomyelinase deficiency (ASMD): safety and efficacy in adults treated for 30 months.

Olipudase alfa, a recombinant human acid sphingomyelinase (ASM), is an enzyme replacement therapy for the treatment of nonneurologic manifestations of acid sphingomyelinase deficiency (ASMD). This ongoing, open-label, long-term study (NCT02004704) assessed safety and efficacy of olipudase alfa following 30 months of treatment in five adult patients with ASMD. There were no deaths, serious or severe events, or discontinuations during 30 months of treatment.

A novel approach for quantitation of glucosylceramide in human dried blood spot using LC-MS/MS.

Background: Glucosylceramide, an efficacy biomarker for Gaucher Type 1 disease, exhibits poor solubility in polar solvents and whole blood which makes it difficult to prepare a homogenous blood standard.

Results: We developed a novel method using standard addition approach by spiking a small volume of analyte solution on the surface of prespotted dried blood spot. The whole spots were punched out for subsequent extraction and LC-MS/MS analysis.

Reassessment of tigecycline bone concentrations in volunteers undergoing elective orthopedic procedures.

The goal of the this study was to re-evaluate tigecycline bone concentrations in subjects undergoing elective orthopedic surgery, using multiple doses and a more robust bone assay than was used in a previous study. Each subject received three intravenous doses of tigecycline (one 100-mg infusion followed by two 50-mg infusions, each administered over 30 minutes). A single bone sample was collected from each subject at one of the following times: 1, 2, 4, 6, 8, or 12 hours after the third dose.

Ultrasensitive and automated 1 pg/ml fluticasone propionate assay in human plasma using LC-MS/MS.

Background: To develop and validate an ultrasensitive bioanalytical assay for quantitation of fluticasone propionate in human plasma, aliquots of 0.6 ml of K(3)EDTA human plasma were treated with zinc sulfate solution and loaded onto a preconditioned SPE plate. The sample solutions were washed, eluted, dried and reconstituted.

Challenges in urine bioanalytical assays: overcoming nonspecific binding.

Dr Allena Ji is the Director of Bioanalytical Services, XenoBiotic Laboratories, Inc., NJ, USA. She has worked in the bioanalytical field for many years and accumulated rich experience in LC-MS/MS method development, method validation and sample analysis under GLP compliance in large pharmaceutical company and contract laboratory settings.

A sensitive human bone assay for quantitation of tigecycline using LC/MS/MS.

Tigecycline (Tygacil,Wyeth) is a first-in-class, broad spectrum antibiotic with activity against multiple-resistant organisms. In order to address the unexpectedly low tigecycline concentrations in human bone samples analyzed using a LC/MS/MS method developed elsewhere, we have developed and validated a new and sensitive human bone assay for the quantitation of tigecycline using LC/MS/MS. The new method utilizes the addition of a stabilizing agent to the human bone sample, homogenization of human bone in a strong acidic-methanol extraction solvent, centrifugation of the bone suspension, separation by liquid chromatography, and detection of tigecycline by mass spectrometry.

A novel antibiotic bone assay by liquid chromatography/tandem mass spectrometry for quantitation of tigecycline in rat bone.

Tigecycline (Tygacil) is a first-in-class, broad spectrum antibiotic with activity against antibiotic-resistant organisms. In rats and humans, tigecycline readily distributes to bone tissue but its accuracy of quantitation via liquid chromatography/mass spectrometry (LC/MS/MS) is hindered by a low extraction recovery when using a conventional plasma extraction method. To overcome this issue, we have identified an effective extraction solvent for quantitation of tigecycline in rat bone.