The importance of being metal-free: The critical choice of column hardware for size exclusion chromatography coupled to high resolution mass spectrometry

Characterization of mRNA therapeutics

Therapeutic messenger RNAs (mRNAs) have emerged as powerful tools in the treatment of complex diseases, especially for conditions that lack efficacious treatment. The successful application of this modality can be attributed to its ability to encode entire proteins. While the large nature of these molecules has supported their success as therapeutics, its extended size creates several analytical challenges. To further support therapeutic mRNA development and its deployment in clinical trials, appropriate methods to support their characterization must be developed. In this review, we describe current analytical methods that have been used in the characterization of RNA quality, identity, and integrity. Advantages and limitations from several analytical techniques ranging from gel electrophoresis to liquid chromatography-mass spectrometry and from shotgun sequencing to intact mass measurements are discussed. We comprehensively describe the application of analytical methods in the measurements of capping efficiency, poly A tail analysis, as well as their applicability in stability studies.

Assessment of chemical stability of monoclonal antibody and antibody drug conjugate administered by pressurized intraperitoneal aerosol chemotherapy

Pressurized intraperitoneal aerosol chemotherapy (PIPAC) is a new therapeutic approach for patients with peritoneal cancer. So far, most published studies investigated the administration of established cytostatic agents through PIPAC. This study aimed to evaluate the effect of PIPAC on two breakthrough anti-cancer agents, specifically anti-PD1 pembrolizumab, and anti-HER2 antibody-drug conjugate (ADC) - trastuzumab-deruxtecan. We conducted systematic analyses on samples of pembrolizumab and trastuzumab-deruxtecan at clinically relevant concentrations before and after PIPAC administration using an experimental setup of a hermetic container system, mimicking the abdominal cavity and using identical features as in clinical use. We utilized a range of chromatographic and spectroscopic techniques to explore potential alterations in the primary, secondary, and tertiary structures of the drugs, focusing on post-translational modifications resulting from the aerosolization. Our findings indicate that PIPAC did not compromise the integrity of tested biopharmaceuticals. The size variants of both drugs, assessed by size exclusion chromatography (SEC), remained unchanged. Reversed-phase liquid chromatography (RPLC) and hydrophobic interaction chromatography (HIC) revealed no significant differences in hydrophobicity variants, the average drug-to-antibody ratio (DAR), or DAR distribution before and after PIPAC treatment. Circular dichroism (CD) spectroscopy confirmed that the secondary and tertiary structures were preserved. While pembrolizumab showed no change in charge variants post-PIPAC, trastuzumab-deruxtecan exhibited a non-negligible change in the quantity of charge variants on the monoclonal antibody itself, while the payload remained unchanged. This shift could possibly be related to the metallic composition of the CapnoPen® device (made of nickel and chromium) used in PIPAC and for these experiments. Together, our results suggest that PIPAC does not alter the structure of pembrolizumab and trastuzumab-deruxtecan, paving the way for future clinical trials.

Microextraction Techniques for Sample Preparation of Amphetamines in Urine: A Comprehensive Review

Psychological disorders and dramatic social problems are serious concerns regarding the abuse of amphetamine and its stimulant derivatives worldwide. Consumers of such drugs experience great euphoria along with serious health problems. Determination and quantification of amphetamine-type stimulants are indispensable skills for clinical and forensic laboratories. Analysis of low drug doses in bio-matrices necessitates applications of simple and also effective preparation steps. The preparation procedures not only eliminate adverse matrix effects, but also provide reasonable clean-up and pre-concentration benefits. The current review presents different methods used for sample preparation of amphetamines from urine as the most frequently used biological matrix. The advantages and limitations of various sample preparation methods were discussed focusing on the miniaturized methods.

Size exclusion chromatography of biopharmaceutical products: From current practices for proteins to emerging trends for viral vectors, nucleic acids and lipid nanoparticles

The 21st century has been particularly productive for the biopharmaceutical industry, with the introduction of several classes of innovative therapeutics, such as monoclonal antibodies and related compounds, gene therapy products, and RNA-based modalities. All these new molecules are susceptible to aggregation and fragmentation, which necessitates a size variant analysis for their comprehensive characterization. Size exclusion chromatography (SEC) is one of the reference techniques that can be applied. The analytical techniques for mAbs are now well established and some of them are now emerging for the newer modalities. In this context, the objective of this review article is: i) to provide a short historical background on SEC, ii) to suggest some clear guidelines on the selection of packing material and mobile phase for successful method development in modern SEC; and iii) to highlight recent advances in SEC, such as the use of narrow-bore and micro-bore columns, ultra-wide pore columns, and low-adsorption column hardware. Some important innovations, such as recycling SEC, the coupling of SEC with mass spectrometry, and the use of alternative detectors such as charge detection mass spectrometry and mass photometry are also described. In addition, this review discusses the use of SEC in multidimensional setups and shows some of the most recent advances at the preparative scale. In the third part of the article, the possibility of SEC for the characterization of new modalities is also reviewed. The final objective of this review is to provide a clear summary of opportunities and limitations of SEC for the analysis of different biopharmaceutical products.

Implementing reversed-phase and hydrophilic interaction liquid chromatography into the characterization of DTPA-ramucirumab conjugate before radiolabeling

Radioimmunoconjugates represent a promising class of therapeutics and diagnostics. The characterization of intermediate chelator-antibody products, i.e., without the radionuclide, is frequently omitted, bringing significant uncertainty in the radioimmunoconjugate preparation. In the present study, we explored the utility of reversed-phase (RPLC) and hydrophilic interaction (HILIC) liquid chromatography with UV detection to characterize ramucirumab stochastically conjugated with p-SCN-Bn-CHX-A"-DTPA chelator (shortly DTPA). The conjugation was well reflected in RPLC chromatograms, while chromatograms from HILIC were significantly less informative. RPLC analyses at the intact level confirmed that the conjugation resulted in a heterogeneous mixture of modified ramucirumab. Moreover, the RPLC of DTPA-ramucirumab confirmed heterogeneous conjugation of all subunits. The peptide mapping did not reveal substantial changes after the conjugation, indicating that most parts of ramucirumab molecules remained unmodified and that the DTPA chelator was bound to various sites. Eventually, the RPLC method for analysis of intact ramucirumab was successfully applied to online monitoring of conjugation reaction in 1 h intervals for a total of 24 h synthesis, which readily reflected the structural changes of ramucirumab in the form of retention time shift by 0.21 min and increase in peak width by 0.22 min. The results were obtained in real-time, practically under 10 min per monitoring cycle. To the best of our knowledge, our study represents the first evaluation of RPLC and HILIC to assess the quality of intermediates during the on-site preparation of radioimmunoconjugates prior to radiolabeling.

Managing nonspecific adsorption to liquid chromatography hardware: A review

The choice of alternative materials over stainless steel hardware in the construction of liquid chromatography systems has unveiled the degree to which nonspecific adsorption impacts the reproducibility of LC methods. Some of the major contributors to nonspecific adsorption losses are charged metallic surfaces and leached metallic impurities, that may interact with the analyte and result in analyte loss and overall poor chromatographic performance. In this review, we describe several mitigation strategies available to chromatographers to minimize nonspecific adsorption to chromatographic systems. Alternative surfaces to stainless steel such as titanium, PEEK, and hybrid surface technologies are discussed. Furthermore, mobile phase additives used to prevent metal ion-analyte interactions are reviewed. Nonspecific adsorption of analytes is not reserved to metallic surfaces, as analytes may adsorb to the surfaces of filters, tubes, and pipette tips during sample preparation. Identifying the source of nonspecific interactions is paramount, as mitigation strategies may differ depending on what stage nonspecific losses are taking place. With this in mind, we discuss diagnostic methods that may help the chromatographer to differentiate losses resulting from sample preparation, and losses during LC runs.

Direct coupling of size exclusion chromatography and mass spectrometry for the characterization of complex monoclonal antibody products

The present study describes the possibilities offered by an innovative bioinert size exclusion chromatography column for size variant characterization of complex monoclonal antibody products. This size exclusion chromatography column includes a novel column hardware surface. The column was prepared from metallic hardware components that were treated to have prototype hydrophilically modified hybrid organic–inorganic silica surfaces called hybrid surface technology. This provides a significant reduction in nondesired hydrophobic and electrostatic interactions that can occur between column and analyte when performing size exclusion chromatography analysis with volatile mobile phase.

Compared to a reference stainless‐steel column packed with the same batch of packing material, peak tailing, band broadening, and above all recovery of high molecular weight species were distinctly improved for all types of monoclonal antibody products. Based on our observations, we found that 50 mM ammonium acetate in water was a suitable mobile phase offering good compromise in terms of liquid chromatography performance and mass spectrometry sensitivity. In addition, method repeatability (intra‐ and interday relative standard deviations) on elution times and high molecular weight species peak areas were found to be excellent.

By using this innovative size exclusion chromatography material, the low and high molecular weight species contained in various stressed and nonstressed monoclonal antibody products were successfully characterized with mass spectrometry detection.

Size Exclusion and Ion Exchange Chromatographic Hardware Modified with a Hydrophilic Hybrid Surface

Certain biomolecules have proven to be difficult to analyze by liquid chromatography (LC), especially under certain chromatographic conditions. The separation of proteins in aqueous mobile phases is one such example because there is the potential for both hydrophobic and ionic secondary interactions to occur with chromatographic hardware to the detriment of peak recovery, peak shape, and the overall sensitivity of the LC analysis. To decrease non-specific adsorption and undesired secondary interactions between column hardware and biomolecules, we have developed and applied a new hydrophilically modified hybrid surface (h-HST) for size exclusion chromatography (SEC) and anion exchange (AEX) separations of proteins and nucleic acids. This surface incorporates additional oxygen and carbon atoms onto an ethylene bridge hybrid siloxane polymer. As a result, it exhibits reduced electrostatic properties and hydrophilicity that facilitates challenging aqueous separations. Flow injection tests with a phosphate buffer showed superior protein recovery from an h-HST frit when compared to unmodified ethylene-bridged hybrid HST, titanium, stainless steel, and PEEK frits. When applied to SEC of rituximab, ramucirumab, and trastuzumab emtansine with a 50 mM ammonium acetate buffer, this new hydrophilic chromatographic hardware yielded improved monomer and aggregate recovery, higher plate numbers, and more symmetrical peaks. AEX columns also benefited from h-HST hardware. An acidic mAb (eculizumab) showed improved recovery, more stable retention, and a sharper peak when eluted from an h-HST versus SS column. Moreover, AEX separations of intact mRNA samples (Cas9 and EPO mRNA) were improved, where it was seen that h-HST column hardware provided higher sensitivity and more repeatable peak areas from injection to injection. As such, there is significant potential in the use of h-HST chromatographic hardware to facilitate more robust and more sensitive analyses for a multitude of challenging separations and analytes.

Bispecific antibody characterization by a combination of intact and site-specific/chain-specific LC/MS techniques

Bispecific antibodies (bsAbs) are considered as an important class of biopharmaceutical drugs, with about 160 products in clinical trials. From an analytical point of view, the correct chain-association is one of the most critical challenge to monitor during bsAbs development and production. In the present study, a full analytical workflow has been developed based on the use of various chromatographic modes: size exclusion chromatography (SEC), ion exchange chromatography (IEX), reversed phase liquid chromatography (RPLC), and hydrophilic interaction chromatography (HILIC), all combined with high resolution mass spectrometry (MS). This analytical strategy was applied to Hemlibra® (emicizumab), which is certainly the most successful commercial bsAb to date. Using this strategy, it was possible to monitor the presence of mispaired bsAb species and detect and identify additional post-translational modifications (PTMs).

Impact of Nonspecific Adsorption to Metal Surfaces in Ion Pair-RP LC-MS Impurity Analysis of Oligonucleotides

Nonspecific adsorption has been a consistent challenge in the analysis of oligonucleotides. Nonspecific adsorption is a result of interactions between charged acidic analytes and adsorption sites present in metallic surfaces located in the fluidic path of chromatography systems. Due to their high surface area, adsorption to column frits is especially concerning. Poor peak shape, low recovery and compromised LOQ have been associated with this phenomenon. Alternative methods including substitution of stainless steel for different hardware materials and mobile phase additives have been explored in an attempt to minimize this issue. Chemical modification of metal surfaces using hybrid surface technology (HST) by-passes the limitation of stainless steel construction material by forming a hybrid organic/inorganic layer that acts as a barrier and limits nonspecific interactions. In this study we explore the implications of this new technology in sensitive analysis and determination of relative impurity levels of oligonucleotides. Higher relative impurity levels and better reproducibility were obtained with columns using HST.