Liquid Profiling for Cancer Patient Stratification in Precision Medicine-Current Status and Challenges for Successful Implementation in Standard Care.

Circulating tumor DNA (ctDNA), accurately described by the term liquid profiling (LP), enables real-time assessment of the tumor mutational profile as a minimally invasive test and has therefore rapidly gained traction, particular for the management of cancer patients. By LP, tumor-specific genetic alterations can be determined as part of companion diagnostics to guide selection of appropriate targeted therapeutics. Because LP facilitates longitudinal monitoring of cancer patients, it can be used to detect acquired resistant mechanisms or as a personalized biomarker for earlier detection of disease recurrence, among other applications. However, LP is not yet integrated into routine care to the extent that might be expected. This is due to the lack of harmonization and standardization of preanalytical and analytical workflows, the lack of proper quality controls, limited evidence of its clinical utility, heterogeneous study results, the uncertainty of clinicians regarding the value and appropriate indications for LP and its interpretation, and finally, the lack of reimbursement for most LP tests. In this review, the value proposition of LP for cancer patient management and treatment optimization, the current status of implementation in standard care, and the main challenges that need to be overcome are discussed in detail.

Liquid profiling of circulating tumor DNA in colorectal cancer: steps needed to achieve its full clinical value as standard care.

The analysis of circulating tumor DNA (ctDNA) is at the threshold of implementation into standard care for colorectal cancer (CRC) patients. However, data about the clinical utility of liquid profiling (LP), its acceptance by clinicians, and its integration into clinical workflows in real-world settings remain limited. Here, LP tests requested as part of routine care since 2016 were retrospectively evaluated. Results show restrained request behavior that improved moderately over time, as well as reliable diagnostic performance comparable to translational studies, with an overall agreement of 91.7%. Extremely low ctDNA levels at < 0.1% in over 20% of cases, a high frequency of concomitant driver mutations (in up to 14% of cases), and ctDNA levels reflecting the clinical course of disease were revealed. However, certain limitations hampering successful translation of ctDNA into clinical practice were uncovered, including the lack of clinically relevant ctDNA thresholds, appropriate time points of LP requests, and integrative evaluation of ctDNA, imaging, and clinical findings. In conclusion, these results highlight the potential clinical value of LP for CRC patient management and demonstrate issues that need to be addressed for successful long-term implementation in clinical workflows.

Coupling size exclusion chromatography to ultracentrifugation improves detection of exosomal proteins from human plasma by LC-MS.

OBJECTIVES: Exosomes are small lipid bilayer vesicles that are defined by their endocytic origin and size range of 30-140 nm. They are constantly produced by different cell types, by both healthy and abnormal cells, and can be isolated from almost all body fluids.Little information exists in isolating exosomes from plasma due to the complexity of its content and the presence of contaminating plasma proteins. DESIGN AND METHODS: We carried-out liquid chromatography-mass spectrometry (LC-MS/MS) analyses of plasma-derived vesicles from 4 healthy donors obtained by 2 coupled methodologies: Ultracentrifugation (UC) coupled with size-exclusion chromatography (SEC) to isolate and subsequently enrich exosomes.We compared the proteins detected by UC alone and UC coupled with SEC. RESULTS: In the coupled UC + SEC methodology we found 52.25% more proteins enriched in exosomes as CD9, Annexins, YWHAZ (14-3-3 family) and others, than by using UC alone. There is also a reduction of 98.8% of contaminating plasma proteins by coupling UC and SEC in comparison to using UC alone. CONCLUSIONS: We conclude that exosomes can be successfully isolated from plasma using a very simple combination of standard methods, which could largely improve the proteomics profiling of plasma exosomes.

Therapeutic drug monitoring (TDM) of 5-fluorouracil (5-FU): new preanalytic aspects.

Background 5-Fluorouracil (5-FU) is frequently used for the treatment of gastrointestinal tumors. The pharmacological effect of 5-FU is influenced by genetic polymorphisms as well as differently dosed regimens. Currently, 5-FU is generally administered as a continuous infusion via an implanted port system using a body surface area (BSA)-based dose calculation. In order to optimize treatment, the area under the curve (AUC) can be estimated to allow for individual dose adjustment. A 5-FU AUC range between 20 and 30 [mg×h×L] is recommended. The aim of the current study was to assess if blood for AUC analysis could also be drawn at the side where the port system had been placed. Methods We collected EDTA blood samples of patients receiving infusional 5-FU simultaneously from different sampling points (right/left cubital vein). 5-FU concentrations were measured in a steady-state equilibrium based on nanoparticle immunoassay (My5-FU; Saladax). Results A total of 39 patients took part in this study. About half of the patients did not reach the target 5-FU concentration window (37% were under- and 16% of the patients were overdosed). Calculated median AUC was 23.3 for the right arm (range 5.8-59.4) and a median of 23.4 for the left arm (range 5.3-61.0). AUC values showed no difference between right compared to left arms (p=0.99). Conclusions In all, these results confirm that a high percentage of patients are not treated with 5-FU doses reaching suggested AUC levels of 20-30. The location of venepuncture, however, had no impact on the results of plasma 5-FU concentration.