Quantification of Oligonucleotide Therapeutics in Plasma Using a Generic Kit-Based Approach

Importance of the Topic

The accurate bioanalytical quantification of oligonucleotide therapeutics in plasma is critical for drug development, pharmacokinetics, and safety assessments. Traditional LC-MS sample preparation workflows are time-consuming, require extensive method development and skilled personnel, and lack a universal extraction approach. A streamlined, kit-based workflow addresses these challenges by offering consistency, reduced development time, and high analytical performance needed for sensitive and robust assays.

Objectives and Study Overview

This study aims to evaluate a generic, kit-based sample preparation and extraction workflow for therapeutic oligonucleotides in plasma using a prototype AX-SPE microplate kit. Specific goals include:

• Demonstrating high recovery and reproducibility across diverse oligonucleotide chemistries without bespoke method development
• Automating the workflow on the Andrew+™ Pipetting Robot for standardized processing
• Assessing analytical performance metrics such as recovery, matrix effects, accuracy, and precision

Methodology and Instrumentation

A panel of oligonucleotide therapeutics was tested, including unmodified dT mixes (15–35 mer), phosphorothioated antisense oligonucleotides (GEM91, GEM132), GalNAc-conjugated siRNA, single-stranded 20-mer DNA, and lipid-conjugated antisense oligonucleotides. Plasma samples (12.5–300 µL, optimized at 100 µL) underwent protein digestion for 1 hour at 55 °C, followed by extraction with the prototype AX-SPE microplate kit. Automated processing was performed on the Andrew+™ Pipetting Robot using pre-measured, detergent-free reagents. LC-MS/MS analysis employed a Waters Xevo® TQ-XS tandem quadrupole mass spectrometer (ESI-) coupled to an ACQUITY I-Class PLUS UPLC system with an ACQUITY PREMIER Oligonucleotide BEH C18 column (1.7 µm, 2.1 × 50 mm). A shallow gradient of 1% HFIP and 0.1% DIPEA in water versus acetonitrile at 0.6 mL/min enabled a 5-minute run time with 1–30 µL injections.

Main Results and Discussion

The prototype kit delivered consistent plasma recoveries above 75% across all oligonucleotides. Intra-assay, inter-day, and inter-user precision remained within 15% RSD, demonstrating robust reproducibility. Matrix effects were minimal, ranging from ‑35% to +1.4%. Linearity was confirmed for extracted sample volumes (12.5–300 µL) and injection volumes (1–30 µL). Automated extraction on the Andrew+ Robot exhibited accuracy within ±15% of expected values, underscoring comparability to manual methods and suitability for high-throughput bioanalysis.

Benefits and Practical Applications

• Universal kit-based workflow reduces method development time and specialized expertise
• Automated processing enhances throughput and consistency, minimizing user variability
• High recovery and reproducibility support reliable pharmacokinetic and toxicology studies
• Pre-measured, lot-traceable reagents ensure quality control and regulatory compliance

Future Trends and Opportunities

The kit-based approach may be extended to other biomatrices such as tissues or cerebrospinal fluid, and adapted for emerging oligonucleotide modalities. Integration with advanced robotic platforms and data analytics could streamline end-to-end workflows. Continuous improvements in mass spectrometry sensitivity and reagent design will further enhance assay performance for next-generation nucleic acid therapeutics.

Conclusion

A standardized, generic kit-based sample preparation protocol automated on the Andrew+ Pipetting Robot provides a robust, reproducible, and efficient solution for quantifying a wide range of therapeutic oligonucleotides in plasma. This approach delivers high recoveries, minimal matrix effects, and consistent precision, supporting the needs of modern bioanalytical laboratories.

References

• Waters Technology Library Literature Code 720008066EN
• Waters Technology Library Literature Code 720008067EN
• Waters Technology Library Literature Code 720008068EN