Magnitude of Urine Albumin and KIM-1 Changes Can be Used to Differentiate Glomerular Injury From Tubular Injury in Rats.

Emerging urinary kidney safety biomarkers have been evaluated in recent years and have been shown to be superior to the serum parameters blood urea nitrogen (BUN) and creatinine (sCr) for monitoring kidney injury in the proximal tubule. However, their potential application in differentiating the location of the initial kidney injury (eg, glomerulus vs tubule) has not been fully explored. Here, we assessed the performance of two algorithms that were constructed using either an empirical or a mathematical model to predict the site of kidney injury using a data set consisting of 22 rat kidney toxicity studies with known urine biomarker and histopathologic outcomes. Two kidney safety biomarkers used in both models, kidney injury molecule 1 (KIM-1) and albumin (ALB), were the best performers to differentiate glomerular injury from tubular injury. The performance of algorithms using these two biomarkers against the gold standard of kidney histopathologic examination showed high sensitivity in differentiating the location of the kidney damage to either the glomerulus or the proximal tubules. These data support the exploration of such an approach for use in clinical settings, leveraging urinary biomarker data to aid in the diagnosis of either glomerular or tubular injury where histopathologic assessments are not conducted.

Anti-Drug Antibody Incidence Comparison of Therapeutic Proteins Administered Via Subcutaneous vs. Intravenous Route.

Subcutaneous (SC) administration of therapeutic proteins is perceived to pose higher risk of immunogenicity when compared with intravenous (IV) route of administration (RoA). However, systematic evaluations of clinical data to support this claim are lacking. This meta-analysis was conducted to compare the immunogenicity of the same therapeutic protein by IV and SC RoA. Anti-drug antibody (ADA) data and controlling variables for 7 therapeutic proteins administered by both IV and SC routes across 48 treatment groups were analyzed. RoA was the primary independent variable of interest while therapeutic protein, patient population, adjusted dose, and number of ADA samples were controlling variables. Analysis of variance was used to compare the ADA incidence between IV and SC RoA, while accounting for controlling variables and potential interactions. Subsequently, 10 additional therapeutic proteins with ADA data published for both IV and SC administration were added to the above 7 therapeutic proteins and were evaluated for ADA incidence. RoA had no statistically significant effect on ADA incidence for the initial dataset of 7 therapeutic proteins (p = 0.55). The only variable with a significant effect on ADA incidence was the therapeutic protein. None of the other controlling variables, including their interactions with RoA, was significant. When all data from the 17 therapeutic proteins were pooled, there was no statistically significant effect of RoA on ADA incidence (p = 0.81). In conclusion, there is no significant difference in ADA incidence between the IV and SC RoA, based on analysis of clinical ADA data from 17 therapeutic proteins.

Points to consider regarding the use and implementation of virtual controls in nonclinical general toxicology studies.

The replacement of a proportion of concurrent controls by virtual controls in nonclinical safety studies has gained traction over the last few years. This is supported by foundational work, encouraged by regulators, and aligned with societal expectations regarding the use of animals in research. This paper provides an overview of the points to consider for any institution on the verge of implementing this concept, with emphasis given on database creation, risks, and discipline-specific perspectives.

Considerations for the Identification and Conveyance of Clinical Pathology Findings in Preclinical Toxicity Studies: Results From the 9th ESTP International Expert Workshop.

The European Society of Toxicologic Pathology (ESTP) organized a panel of 24 international experts from many fields of toxicologic clinical pathology (e.g., industry, academia, and regulatory) that came together in 2021 to align the use of terminology to convey the importance of clinical pathology findings in preclinical toxicity studies. An additional goal consisted of how to identify important findings in standard and nonstandard clinical pathology associated endpoints. This manuscript summarizes the information and opinions discussed and shared at the ninth ESTP International Expert Workshop, April 5 to 6, 2022. In addition to terminology usage, the workshop considered topics related to the identification and conveyance of the importance of test item-related findings. These topics included sources of variability, comparators, statistics, reporting, correlations to other study data, nonstandard biomarkers, indirect/secondary findings, and an overall weight-of-evidence approach.

Translation of nonclinical to clinical safety findings for 27 biotherapeutics.

Human adverse drug reactions (ADRs), and in vivo nonclinical adverse and nonadverse findings, were identified in 27 biotherapeutic programs and placed into organ categories to determine translation. The sensitivity of detecting human ADRs was 30.8% with a positive predictive value (PPV) of 53.3% for nonclinical adverse findings; sensitivity increased to 67.3% and PPV fell to 35.0% when including nonadverse findings. Nonclinical findings were associated with a greater likelihood of a human ADR in that organ category, especially for adverse findings [positive likelihood ratio (LR+) >10 (lower 95% confidence interval [CI] of >5)]. The specificity and negative predictive value (NPV) were very high (>85%). A lack of nonclinical findings in an organ category was associated with a lower likelihood of a human ADR in that organ category. About 40-50% of human ADRs and nonclinical adverse findings, and about 30% of nonclinical nonadverse findings, were attributed to pharmacology. Slightly more than half of the human ADRs with a translating nonclinical finding had findings in animals that could be considered very similar. Overall, 38% of nonclinical findings translated to a human ADR at the organ category level. When nonclinical findings did not translate to humans, the cause was usually higher exposures or longer dosing in animals. All programs with human ADRs attributed to immunogenicity also had nonclinical adverse or nonadverse findings related to immunogenicity. Overall, nonclinical adverse and nonadverse findings were useful in predicting human ADRs, especially at an organ category level, and the majority of human ADRs were predicted by nonclinical toxicity studies.

Effects of 2,3-DPG knockout on SCD phenotype in Townes SCD model mice.

Sickle cell disease (SCD) is a severe, multisystemic hematological disorder that impacts nearly every major organ in adults. The current approved treatments for SCD directly target mutant hemoglobin or address downstream disease pathology. Several compounds targeting reduction of 2,3-DPG by activation of Pyruvate Kinase-R are currently being evaluated in SCD patients. In this study, we genetically engineered a mouse lacking 2,3-DPG on the Townes SCD mouse model background and evaluated the effects of 2,3-DPG loss on disease pathology. Animals lacking 2,3-DPG showed improvements in hematological markers and reductions in RBC sickling relative to native Townes mice, however, minimal difference in organ damage was observed in 2,3-DPG deficient mice compared to native Townes animals. When animals lacking 2,3-DPG were dosed with a compound designed to increase hemoglobin oxygen affinity, oxygen delivery related toxicity was observed.

Toxicological Assessments of a Pandemic COVID-19 Vaccine-Demonstrating the Suitability of a Platform Approach for mRNA Vaccines.

The emergence of SARS-CoV-2 at the end of 2019 required the swift development of a vaccine to address the pandemic. Nonclinical GLP-compliant studies in Wistar Han rats were initiated to assess the local tolerance, systemic toxicity, and immune response to four mRNA vaccine candidates encoding immunogens derived from the spike (S) glycoprotein of SARS-CoV-2, encapsulated in lipid nanoparticles (LNPs). Vaccine candidates were administered intramuscularly once weekly for three doses at 30 and/or 100 µg followed by a 3-week recovery period. Clinical pathology findings included higher white blood cell counts and acute phase reactant concentrations, lower platelet and reticulocyte counts, and lower RBC parameters. Microscopically, there was increased cellularity (lymphocytes) in the lymph nodes and spleen, increased hematopoiesis in the bone marrow and spleen, acute inflammation and edema at the injection site, and minimal hepatocellular vacuolation. These findings were generally attributed to the anticipated immune and inflammatory responses to the vaccines, except for hepatocyte vacuolation, which was interpreted to reflect hepatocyte LNP lipid uptake, was similar between candidates and resolved or partially recovered at the end of the recovery phase. These studies demonstrated safety and tolerability in rats, supporting SARS-CoV-2 mRNA-LNP vaccine clinical development.

Overview of Session 3 Mechanisms of Decreased Erythropoiesis and Erythroid Cell Injury.

This session, held during the 41st Annual STP Symposium, focused on mechanisms of decreased erythropoiesis and erythroid cell injury. The speakers provided comprehensive overviews of physiologic and pathologic erythropoiesis, reviewed various mechanisms of erythroid cell injury, and shared innovative investigative research with the audience.

The use of emerging safety biomarkers in nonclinical and clinical safety assessment - The current and future state: An IQ DruSafe industry survey.

Pharmaceutical and biotechnology companies rarely disclose their use of translational emerging safety biomarkers (ESBs) during drug development, and the impact of ESB use on the speed of drug development remains unclear. A cross-industry survey of 20 companies of varying size was conducted to understand current trends in ESB use and future use prospects. The objectives were to: (1) determine current ESB use in nonclinical and clinical drug development and impact on asset advancement; (2) identify opportunities, gaps, and challenges to greater ESB implementation; and (3) benchmark perspectives on regulatory acceptance. Although ESBs were employed in only 5-50% of studies/programs, most companies used ESBs to some extent, with larger companies demonstrating greater nonclinical use. Inclusion of ESBs in investigational new drug applications (INDs) was similar across all companies; however, differences in clinical trial usage could vary among the prevailing health authority (HA). Broader implementation of ESBs requires resource support, cross-industry partnerships, and collaboration with HAs. This includes generating sufficient foundational data, demonstrating nonclinical to clinical translatability and practical utility, and clearly written criteria by HAs to enable qualification. If achieved, ESBs will play a critical role in the development of next-generation, translationally-tailored standard laboratory tests for drug development.

Investigation on the Effect of Capillary Microsampling on Hematologic and Toxicokinetic Evaluation in Regulatory Safety Studies in Mice.

Microsampling techniques enable the minimization of blood collection volume from animals and subsequent handling of the blood samples or their derived plasma or serum samples. This offers advantages over conventional large-volume sampling, such as eliminating the need for satellite animals and improving animal welfare aspects, and providing the opportunity for additional assessments in small animals where blood volume constraints limit endpoints. This study evaluated the feasibility of implementation of capillary microsampling (CMS) in a single-dose study in mice with the ultimate goal of enabling its use in toxicology studies. The focus was on the impact of microsampling on toxicokinetic assessment and on the subsequent hematology assessment in the same animal. A seventy (70)-µL blood collection via CMS from the tail vein had a minimal effect on the hematology parameters of mice (strain C57BL/6) in samples taken within 24 h of blood collection. TK parameters were similar in plasma samples collected via CMS and cardiac puncture sampling. A bioanalytical assay was developed which enabled the quantification of concentration of both the parent drug and a metabolite using only 5-µL plasma sample per analysis. Incurred sample reanalysis (ISR), unexpected event investigation, and re-assay were successfully performed on the limited samples (≤ 20 µL) collected from CMS. The results of this study confirmed the feasibility of implementing CMS in regulated mouse toxicity studies and demonstrated that it is possible to eliminate or reduce satellite animals.

Next-Generation DILI Biomarkers: Prioritization of Biomarkers for Qualification and Best Practices for Biospecimen Collection in Drug Development.

The diagnosis and management of drug-induced liver injury (DILI) remains a challenge in clinical trials in drug development. The qualification of emerging biomarkers capable of predicting DILI soon after the initiation of treatment, differentiating DILI from underlying liver disease, identifying the causal entity, and assigning appropriate treatment options after DILI is diagnosed are needed. Qualification efforts have been hindered by lack of properly stored and consented biospecimens that are linked to clinical data relevant to a specific context of use. Recommendations are made for biospecimen collection procedures, with the focus on clinical trials, and for specific emerging biomarkers to focus qualification efforts.

Interpretative considerations for clinical pathology findings in nonclinical toxicology studies.

The interpretation of clinical pathology results from nonclinical safety studies is a fundamental component in hazard identification of new drug candidates. The ever-increasing complexity of nonclinical safety studies and sophistication of modern analytical methods have made the interpretation of clinical pathology information by a highly trained subject matter expert imperative. Certain interpretive techniques are particularly effective in the identification and characterization of clinical pathology effects. The purpose of this manuscript is to provide an overview of contemporary interpretive practices for clinical pathology results and to provide nonbinding recommendations aimed at improving consistency, quality, and overall value of clinical pathology interpretations generated in support of nonclinical toxicology studies.

Overview and considerations for the reporting of clinical pathology interpretations in nonclinical toxicology studies.

Clinical pathology reporting practices are diverse among individuals and organizations involved in nonclinical toxicology studies. Clear, informative, and consistent reporting of clinical pathology results increases their value and avoids misinterpretation, resulting in decreased drug development costs. In recent years, certain common practices in clinical pathology reporting have been embraced by industry leaders and more consistently utilized across the pharmaceutical industry. The purpose of this manuscript is to review current clinical pathology reporting practices and to provide nonbinding suggestions to improve consistency, quality, and value of clinical pathology reports generated in support of nonclinical toxicology studies.

Practical Strategies for Navigating Toxicologic Pathology in One's Early Career and Beyond!

The toxicologic pathologist plays a vital role in the scientific community, using their unique blend of diagnostic and investigative skills to advance biomedical research, public health, drug discovery, or regulatory practices. But what exactly do toxicologic pathologists contribute? Where do these specialized professionals work? How can toxicologic pathologists maximize their efficiency and potential? To enlighten students and trainees, as well as early- or mid-career toxicologic pathologists, or even those approaching retirement, the Career Development and Outreach Committee of the Society of Toxicologic Pathology (STP) sponsored a career development workshop entitled "Practical Strategies for Navigating Toxicologic Pathology in One's Early Career…and Beyond!" in conjunction with the STP 37th annual symposium. The workshop featured toxicologic pathologists from contract research organizations and the pharmaceutical industry, who provided their perspectives on career preparation, evolving veterinary pathologist roles within various sectors of toxicologic pathology, the fundamentals of safety assessment, logistics of projects involving good laboratory practices, tools for effective interpretation and communication of anatomic and clinical pathology results, and a recap of scientific resources available to support the toxicologic pathologist in his or her journey. This article provides brief summaries of the talks presented during this career development workshop.

Principles for Assessing Adversity in Toxicologic Clinical Pathology.

There is limited direction in the literature or regulatory guidance on determination of adversity for clinical pathology (CP) biomarkers in preclinical safety studies. Toxicologic clinical pathologists representing the American Society for Veterinary Clinical Pathology-Regulatory Affairs Committee and Society of Toxicologic Pathology-Clinical Pathology Interest Group identified principles, overall approach, and unique considerations for assessing adversity in CP data interpretation to provide a consensus opinion. Emphasized is the need for pathophysiologic context and a weight-of-evidence approach. Most CP biomarkers do not have the potential to be adverse in isolation, regardless of magnitude of change. Rather, they quantify or describe the impact of effects, provide adjunct or supportive information regarding a process or pathogenesis, and provide translational biomarkers of effect. Most often, CP changes are part of a constellation of findings that collectively are adverse. Thus, most CP changes must be interpreted in conjunction with other study findings and require contextual and integrative interpretation. Exceptions include critical CP changes without correlates that indicate a health risk in the tested species. Overall, CP changes should not be interpreted in isolation and their adversity is best addressed with an integrated approach.

Interpreting and Integrating Clinical and Anatomic Pathology Results.

The continuing education course on integrating clinical and anatomical pathology data was designed to communicate the importance of using a weight of evidence approach to interpret safety findings in toxicology studies. This approach is necessary, as neither clinical nor anatomic pathology data can be relied upon in isolation to fully understand the relationship between study findings and the test article. Basic principles for correlating anatomic pathology and clinical pathology findings and for integrating these with other study end points were reviewed. To highlight these relationships, a series of case examples, presented jointly by a clinical pathologist and an anatomic pathologist, were used to illustrate the collaborative effort required between clinical and anatomical pathologists. In addition, the diagnostic utility of traditional liver biomarkers was discussed using results from a meta-analysis of rat hepatobiliary marker and histopathology data. This discussion also included examples of traditional and novel liver and renal biomarker data implementation in nonclinical toxicology studies to illustrate the relationship between discrete changes in biochemistry and tissue morphology.

Reducing blood volume requirements for clinical pathology testing in toxicologic studies-points to consider.

In preclinical safety assessment, blood volume requirements for various endpoints pose a major challenge. The goal of this working group was to review current practices for clinical pathology (CP) testing in preclinical toxicologic studies, and to discuss advantages and disadvantages of methods for reducing blood volume requirements. An industry-wide survey was conducted to gather information on CP instrumentation and blood collection practices for hematology, clinical biochemistry, and coagulation evaluation in laboratory animals involved in preclinical studies. Based on the survey results and collective experience of the authors, the working group proposes the following "points to consider" for CP testing: (1) For most commercial analyzers, 0.5 mL and 0.8 mL of whole blood are sufficient for hematology and biochemistry evaluation, respectively. (2) Small analyzers with low volume requirements and low throughput have limited utility in preclinical studies. (3) Sample pooling or dilution is inappropriate for many CP methods. (4) Appropriate collection sites should be determined based on blood volume requirements and technical expertise. (5) Microsampling does not provide sufficient volume given current analyzer and quality assurance requirements. (6) Study design considerations include: the use of older/larger animals (rodents), collection of CP samples before toxicokinetic samples, use of separate subsets of mice for hematology and clinical biochemistry testing, use of a priority list for clinical biochemistry, and when possible, eliminating coagulation testing.

STP Best Practices for Evaluating Clinical Pathology in Pharmaceutical Recovery Studies.

The Society of Toxicologic Pathology formed a working group in collaboration with the American Society for Veterinary Clinical Pathology to provide recommendations for the appropriate inclusion of clinical pathology evaluation in recovery arms of nonclinical toxicity studies but not on when to perform recovery studies. Evaluation of the recovery of clinical pathology findings is not required routinely but provides useful information on risk assessment in nonclinical toxicity studies and is recommended when the ability of the organ to recover is uncertain. The study design generally requires inclusion of concurrent controls to separate procedure-related changes from test article-related changes, but return of clinical pathology values toward baseline may be sufficient in some cases. Evaluation of either a select or full panel of standard hematology, coagulation, and serum and urine chemistry biomarkers can be scientifically justified. It is also acceptable to redesignate dosing phase animals to the recovery phase or vice versa to optimize data interpretation. Assessment of delayed toxicity during the recovery phase is not required but may be appropriate in development programs with unique concerns. Evaluation of the recovery of clinical pathology data for vaccine development is required and, for efficacy markers, is recommended if it furthers pharmacologic understanding.

Best practices for veterinary toxicologic clinical pathology, with emphasis on the pharmaceutical and biotechnology industries.

The purpose of this paper by the Regulatory Affairs Committee (RAC) of the American Society for Veterinary Clinical Pathology (ASVCP) is to review the current regulatory guidances (eg, guidelines) and published recommendations for best practices in veterinary toxicologic clinical pathology, particularly in the pharmaceutical and biotechnology industries, and to utilize the combined experience of ASVCP RAC to provide updated recommendations. Discussion points include (1) instrumentation, validation, and sample collection, (2) routine laboratory variables, (3) cytologic laboratory variables, (4) data interpretation and reporting (including peer review, reference intervals and statistics), and (5) roles and responsibilities of clinical pathologists and laboratory personnel. Revision and improvement of current practices should be in alignment with evolving regulatory guidance documents, new technology, and expanding understanding and utility of clinical pathology. These recommendations provide a contemporary guide for the refinement of veterinary toxicologic clinical pathology best practices.

"Candidatus Mycoplasma haemomacaque" and Bartonella quintana bacteremia in cynomolgus monkeys.

Here, we report latent infections with Bartonella quintana and a hemotropic Mycoplasma sp. in a research colony of cynomolgus monkeys (Macaca fascicularis). Sequence alignments, evolutionary analysis, and signature nucleotide sequence motifs of the hemotropic Mycoplasma 16S rRNA and RNase P genes indicate the presence of a novel organism.