Quantitation of the next-generation imipridone ONC206 in human plasma by a simple and sensitive UPLC-MS/MS assay for clinical pharmacokinetic application.

ONC206 is an imipridone derivative that is being developed clinically as a single agent given orally in a first-in-human trial (NCT04541082). This ongoing clinical trial requires pharmacokinetic analysis of ONC206 to fully characterize its pharmacologic profile. There is currently no published bioanalytical method for ONC206 quantitation. To understand the clinical pharmacokinetics of ONC206, a sensitive yet simple uHPLC-MS/MS method for quantitation of ONC206 in human plasma was developed. Protein-precipitation allowed rapid and sensitive bioanalytical measurement of ONC206 in human plasma. A Phenomenex Kinetex C18 (50 ×2.1 mm, 1.3 µm, 100 Å) analytical column achieved symmetrical and sharp chromatography peaks of ONC206 and the internal standard, [2H]7-ONC206, which were detected using multiple reaction monitoring. The assay calibration range was 1-500 ng/mL and was best fit by a linear regression model (r2 > 0.99732 ± 0.0010). The method proved accurate (< ± 9% deviation), precise (<11%CV), selective and specific with no interference and low inter-lot matrix variability. ONC206 demonstrated excellent short-term, long-term, and multiple freeze-thaw cycle stability in solution and human plasma. This fully validated method was used to quantitate ONC206 plasma concentrations from patients enrolled in the aforementioned clinical trial at the NCI to demonstrate its clinical applicability.

A quantitative LC-MS/MS method for the determination of tissue brincidofovir and cidofovir diphosphate in a MuPyV-infected mouse model.

Brincidofovir (BCV) is an investigational lipid conjugate of the nucleotide analog cidofovir (CDV), which is being developed as a medical countermeasure for the treatment of smallpox. BCV is active against double-stranded DNA viruses including BK and JC viruses. Here, we validated procedures for quantifying BCV and its pharmacologically active moiety cidofovir diphosphate (CDV-PP) in mouse kidney, brain and spleen tissue homogenates. Following homogenization, BCV and CDV-PP were extracted from the tissues by protein precipitation with their stable, isotopically labeled internal standards, BCV-d6 and 13 C3 15 N2 -CDV-PP. Then, samples were analyzed for BCV by reverse-phase chromatography on a Waters Xterra MS C18 (50 × 2.1 mm, 3.5 µm particle size) column while CDV-PP was analyzed on a Thermo BioBasic AX (50 × 2.1 mm, 5 µm particle size) column using anion exchange chromatography. Detection was achieved by electrospray ionization in positive ion mode on an AB Sciex API-5000 triple quadrupole mass spectrometer. The calibration curves were linear over a range of 1.00-1,000 ng/ml homogenate and 0.050-50.0 ng/ml homogenate for BCV and CDV-PP, respectively. These methods were validated according to US Food and Drug Administration guidance for industry and may be used to characterize the tissue pharmacology of both analytes to advance its preclinical development.

Cytomorphology of Erdheim-Chester disease presenting as a retroperitoneal soft tissue lesion.

Erdheim-Chester disease (ECD) is a rare, multisystem disorder of macrophages. Patients manifest with histiocytic infiltrates that lead to xanthogranulomatous lesions in multiple organ systems. The cytologic features of this disorder are not well characterized. As a result, the cytologic diagnosis of ECD can be very challenging. The aim of this report is to describe the cytomorphology of ECD in a patient presenting with a retroperitoneal soft tissue lesion. A 54-year-old woman with proptosis and diabetes insipidus was found on imaging studies to have multiple intracranial lesions, sclerosis of both femurs and a retroperitoneal soft tissue mass. Fine needle aspiration (FNA) and a concomitant core biopsy of this abnormal retroperitoneal soft tissue revealed foamy, epithelioid and multinucleated histiocytes associated with fibrosis. The histiocytes were immunoreactive for CD68, CD163, Factor XIIIa and fascin, and negative for S100, confirming the diagnosis of ECD. ECD requires a morphologic diagnosis that fits with the appropriate clinical context. This case describes the cytomorphologic features of ECD and highlights the role of cytology in helping reach a diagnosis of this rare disorder.