Factors Governing the Accuracy of Subvisible Particle Counting Methods

Analytical control strategy for biologics. Part I: Foundations

Biologic therapeutics encompass different modalities with vastly different molecular profiles. Despite these differences, all products follow a similar approach to Pharmaceutical Development, which includes an integrated control strategy that relies on a clinical target product profile (TPP), a quality target product profile (QTPP), biophysical, biochemical and biological characterization, elucidation of critical quality attributes (CQAs), and development of an analytical control strategy. Technical and regulatory requirements for biologics development are established in numerous regulatory guidance documents issued by ICH, FDA, EMA, and other bodies. While there is substantial published knowledge on specific studies needed for development of a product, there is no specific guidance on establishing a comprehensive analytical control strategy as part of a modern integrated control strategy. This commentary is Part I of a two-part commentary series on analytical control strategy. In this part we present the foundations that are essential for developing an analytical control strategy to enable efficient lifecycle management across different biologic protein-based therapeutic modalities. In Part II, we will present a stage-appropriate roadmap to implementing an analytical control strategy from discovery research through the commercial life of the biologic.

Association of an Early Interest in Orthopedic Surgery with Match Rate into Orthopedic Surgery

OBJECTIVES

Orthopedic surgery residency is considered one of the most competitive specialties in which to match. Studies examining the factors associated with a successful match have neglected whether participation in an orthopedic interest group (OIG) improves the chances of orthopedic residency match. The goal of this study was to test the hypothesis that participation in the OIG would improve matching into an orthopedic surgery residency.

METHODS

We performed a retrospective cohort study between May 2017 and 2019 at one state-funded medical school. All of the applicants in orthopedic surgery from 2004 to 2019 were identified and contacted for OIG membership status. The Office of Student Affairs provided academic performance data (US Medical Licensing Examination scores and third-year clinical clerkship grades), Alpha Omega Alpha and Gold Humanism Honor Society status, and demographics (race and sex) of applicants.

RESULTS

Between 2004 and 2019, 67 students (56 OIG and 11 non-OIG) applied for orthopedic surgery residency match. The match rate for the OIG was 86% compared with 64% for the non-OIG group, resulting in an adjusted odds ratio (adjusted for academic performance) of 10.23 (95% confidence interval 1.14-92.3, P = 0.038).

CONCLUSIONS

OIG membership was associated with a significantly higher rate of orthopedic surgery residency matches. The higher rate of match associated with OIG membership may be the result of opportunities to diversify a residency application. Future studies are needed to further evaluate the potential association between OIG involvement and orthopedic surgery match.

Imaging Flow Cytometry for Sizing and Counting of Subvisible Particles in Biotherapeutics

Imaging flow cytometry (IFC), a technique originally designed for cellular imaging, is featured by the parallel acquisition in brightfield (BF), fluorescence (FL), and side scattering channels. Introduced to the field of subvisible particle analysis in biopharmaceuticals roughly ten years ago, it has the potential to yield additional information, e.g., on particle origin. Here, we present an extensive, systematic development of masks for IFC image analysis to optimize the accuracy of size determination of polystyrene beads and pharmaceutically relevant particles (protein, silicone oil) in BF and FL channels. Based on the developed masks, particle sizing and counting by IFC are compared to flow imaging microscopy (FIM). Mask verification based on fluorescent polystyrene particles revealed good agreement between sizes obtained from IFC and FIM. In the evaluation of counting accuracy, IFC reported lower concentrations for polystyrene particle standards than FIM. For the analysis of fluorescently stained silicone oil and protein particles however, IFC FL imaging reported higher particle concentrations in the low micrometer size range. Overall, we identified IFC as suitable tool to generate supportive data for particle characterization purposes or trouble shooting activities, but not as routine quantitative technique, e.g., for subvisible particle analysis during drug product development or quality control.

An Interlaboratory Comparison on the Characterization of a Sub-micrometer Polydisperse Particle Dispersion

The measurement of polydisperse protein aggregates and particles in biotherapeutics remains a challenge, especially for particles with diameters of ≈ 1 µm and below (sub-micrometer). This paper describes an interlaboratory comparison with the goal of assessing the measurement variability for the characterization of a sub-micrometer polydisperse particle dispersion composed of five sub-populations of poly(methyl methacrylate) (PMMA) and silica beads. The study included 20 participating laboratories from industry, academia, and government, and a variety of state-of-the-art particle-counting instruments. The received datasets were organized by instrument class to enable comparison of intralaboratory and interlaboratory performance. The main findings included high variability between datasets from different laboratories, with coefficients of variation from 13 % to 189 %. Intralaboratory variability was, on average, 37 % of the interlaboratory variability for an instrument class and particle sub-population. Drop-offs at either end of the size range and poor agreement on maximum counts of particle sub-populations were noted. The mean distributions from an instrument class, however, showed the size-coverage range for that class. The study shows that a polydisperse sample can be used to assess performance capabilities of an instrument set-up (including hardware, software, and user settings) and provides guidance for the development of polydisperse reference materials.

Particles in Biopharmaceutical Formulations, Part 2: An Update on Analytical Techniques and Applications for Therapeutic Proteins, Viruses, Vaccines and Cells

Particles in biopharmaceutical formulations remain a hot topic in drug product development. With new product classes emerging it is crucial to discriminate particulate active pharmaceutical ingredients from particulate impurities. Technical improvements, new analytical developments and emerging tools (e.g., machine learning tools) increase the amount of information generated for particles. For a proper interpretation and judgment of the generated data a thorough understanding of the measurement principle, suitable application fields and potential limitations and pitfalls is required. Our review provides a comprehensive overview of novel particle analysis techniques emerging in the last decade for particulate impurities in therapeutic protein formulations (protein-related, excipient-related and primary packaging material-related), as well as particulate biopharmaceutical formulations (virus particles, virus-like particles, lipid nanoparticles and cell-based medicinal products). In addition, we review the literature on applications, describe specific analytical approaches and illustrate advantages and drawbacks of currently available techniques for particulate biopharmaceutical formulations.

Quantitative Evaluation of Insoluble Particulate Matters in Therapeutic Protein Injections Using Light Obscuration and Flow Imaging Methods

Flow imaging (FI) has emerged as a powerful tool to evaluate insoluble particles derived from protein aggregates as an orthogonal method to light obscuration (LO). However, few reports directly compare the FI and LO method in the size and number of protein particles in commercially available therapeutic protein injections. In this study, we measured the number of insoluble particles in several therapeutic protein injections using both FI and LO, and characterized these particles to compare the analytical performance of the methods. The particle counts measured using FI were much higher than those measured using LO, and the difference depended on the products or features of particles. Some products contained a large number of transparent and elongated particles, which could escape detection using LO. Our results also suggested that the LO method underestimates the size and number of silicone oil droplets in prefilled syringe products compared to the FI method. The count of particles ≥10 μm in size in one product measured using FI exceeded the criteria (6000 counts per container) defined in the compendial particulate matter test using the LO method. Thus precaution should be taken when setting the acceptance criteria of specification tests using the FI method.

Can Cross-Linked Siliconized PFS Come to the Rescue of the Biologics Drug Product?

Silicone can present a challenge during the development of a biologics drug product particularly in pre-filled syringe (PFS). Due to silicone related challenges, substantial changes in components and manufacturing of the PFS are being sought. Cross-linking of the silicone being one of them, can help reduce mobilization of the silicone into drug product whilst retaining its functionality of lubrication during injection. In this work, we systematically compare the stability of a fusion protein and monoclonal antibody formulation in conventionally siliconized and cross-linked siliconized PFS available from commercial manufacturers. The two types of syringes did not influence the aggregation profile of proteins as determined by HP-SEC. Compared to conventionally siliconized PFS, a cross-linked siliconized PFS can have a favorable or indifferent impact (depending on vendor) on the sub-visible particles profile as assessed by light obscuration and microflow imaging. The different PFS after 24 months of long-term storage showed comparable functionality attributes like break-loose/gliding force and silicone oil distribution. Cross-linked siliconized PFS can offer an incremental advantage over conventionally siliconized PFS for the moderately concentrated protein solutions, however the differences in the quality of these PFS amongst manufacturers is an important aspect that needs to be considered as shown in this study.

Taking Subvisible Particle Quantitation to the Limit: Uncertainties and Statistical Challenges With Ophthalmic Products for Intravitreal Injection

Subvisible particles are a critical quality attribute of pharmaceutical products. The reliability of particle quantitation increases with the number of particles in the analyzed sample volume. However, for analyses of low-volume drug products, such as ophthalmic products for intravitreal injection or biopharmaceuticals in general, sample volumes as small as possible should be used to avoid pooling and consequently, the contamination with foreign particles. The aim of our study was to evaluate the variability of particle concentrations obtained by light obscuration measurements to define the minimum required analyzed sample volume to achieve statistically meaningful results by using conditions that are practically feasible. Statistical evaluation suggests that for particle concentrations close to a predefined limit, large sample volumes (a multiple of typical intravitreal product volumes) would be required for a high probability to correctly classify samples with respect to the predefined limit. Below a minimum analyzed volume, even a measurement result of 0 particles does not allow to conclude compliance with the respective particle concentration limit with sufficient certainty. A small analyzed volume could be justified as long as the measurement uncertainty remains acceptable compared with the predefined limit.

A Formulation Development Approach to Identify and Select Stable Ultra-High-Concentration Monoclonal Antibody Formulations With Reduced Viscosities

High protein concentration formulations are required for low-volume administration of therapeutic antibodies targeted for subcutaneous, self-administration by patients. Ultra-high concentrations (≥150 mg/mL) can lead to dramatically increased solution viscosities, which in turn can lead to stability, manufacturing, and delivery challenges. In this study, various categories and individual types of pharmaceutical excipients and other additives (56 in total) were screened for their viscosity reducing effects on 2 different mAbs. The physicochemical stability profile, as well as viscosity ranges, of several candidate antibody formulations, identified and designed based on the results of the excipient screening, were evaluated over a 6-month time period under accelerated and real-time storage conditions. In addition to reducing the solution viscosities to acceptable levels for parenteral administration (using currently available and acceptable delivery devices), the candidate formulations did not result in notable losses of physicochemical stability of the 2 antibodies on storage for 6 months at 25°C. The experiments described here demonstrate the feasibility of a formulation development and selection approach to identify candidate high-concentration antibody formulations with viscosities within pharmaceutically acceptable ranges that do not adversely affect their physicochemical storage stability.

Quantitative analysis of curcumin-loaded alginate nanocarriers in hydrogels using Raman and attenuated total reflection infrared spectroscopy

Core-shell nanocarriers are increasingly being adapted in cosmetic and dermatological fields, aiming to provide an increased penetration of the active pharmaceutical or cosmetic ingredients (API and ACI) through the skin. In the final form, the nanocarriers (NC) are usually prepared in hydrogels, conferring desired viscous properties for topical application. Combined with the high chemical complexity of the encapsulating system itself, involving numerous ingredients to form a stable core and quantifying the NC and/or the encapsulated active without labor-intensive and destructive methods remains challenging. In this respect, the specific molecular fingerprint obtained from vibrational spectroscopy analysis could unambiguously overcome current obstacles in the development of fast and cost-effective quality control tools for NC-based products. The present study demonstrates the feasibility to deliver accurate quantification of the concentrations of curcumin (ACI)-loaded alginate nanocarriers in hydrogel matrices, coupling partial least square regression (PLSR) to infrared (IR) absorption and Raman spectroscopic analyses. With respective root mean square errors of 0.1469 ± 0.0175% w/w and 0.4462 ± 0.0631% w/w, both approaches offer acceptable precision. Further investigation of the PLSR results allowed to highlight the different selectivity of each approach, indicating only IR analysis delivers direct monitoring of the NC through the quantification of the Labrafac®, the main NC ingredient. Raman analyses are rather dominated by the contribution of the ACI which opens numerous perspectives to quantify the active molecules without interferences from the complex core-shell encapsulating systems thus positioning the technique as a powerful analytical tool for industrial screening of cosmetic and pharmaceutical products. Graphical abstract Quantitative analysis of encapuslated active molecules in hydrogel-based samples by means of infrared and Raman spectroscopy.