Symposium and Workshop Sessions are three hours each and Mini-Symposia are scheduled for 1.5 hours each.
To ensure the safety of all attendees, each individual will be required to select their seat for the entire duration of a session. Should you need to exit the room during a session, including during the break, we ask that you return to your selected seat. Session rooms will be sanitized after each course, not at breaks.
Symposia and Workshops are subject to change.
Session Chairs: Jessica Sapiro, Takeda Development Center Americas, Inc, Cambridge, MA;
and Anna Engstrom, Genentech, Redwood City, CA
Immuno-oncology (I-O) therapy has emerged as an innovative and effective approach to cancer treatment. Many different I-O strategies and platforms have been developed to harness the immune system to kill cancer cells, including immune checkpoint inhibitors, adoptive cellular therapies, targeted antibodies, cancer vaccines, oncolytic viruses, and cytokines. As the I-O field continues to evolve, it has become even more critical to build a first-in-human (FIH) safety package that adequately characterizes potential immunotoxicological effects and to understand the translatability (or lack thereof) of nonclinical findings to FIH studies. This Symposium will (1) provide an overview of the current status and future directions of the I-O field; (2) highlight the unique challenges as well as FIH dose selection approaches for different I-O modalities through case studies of nonclinical safety packages for T cell directed bispecific antibodies and therapeutic mRNA cancer vaccines; (3) discuss the importance of different strategies to evaluate the pharmacodynamic activity and potential immunotoxicity of I-O candidates in FIH-enabling toxicology studies; and (4) conclude with a regulator’s perspective on the expectations for FIH safety packages for I-O drugs, including case-based examples of safety packages that were accepted or placed on clinical hold. This Symposium is endorsed by the ACT Early Career Professional Subcommittee.
The field of I-O has brought forward a number of products that are already providing clinical benefit to patients with cancer, including therapeutic cytokines, immune checkpoint inhibitors, T cell bispecifics, and engineered T cells. This extensive clinical experience is fueling the continued refinement of existing products and the development of next-generation I-O therapies. In addition, the potential benefit of oncolytic vaccines and gene therapies is becoming increasingly realized, and numerous other modalities are beginning to be tested for their ability to modulate antitumor immune responses in the tumor microenvironment. Further innovation in the I-O space will be driven by the identification of more relevant biomarkers and the use of personalized medicine approaches, and it will require a thorough understanding of how to combine therapies based on mechanism and/or temporality. The stage is set for transformative I-O therapies to be at the center of achieving deeper and more durable results for patients with cancer.
T cell redirecting paradigms include CD3 bispecific antibodies, which act by simultaneously binding to CD3 on T cells and tumor-associated antigens, leading to the formation of a cytolytic synapse and subsequent tumor cell killing. The development of T cell redirected therapies can pose specific preclinical and clinical safety challenges, including the potential for narrow therapeutic windows, systemic cytokine release, and on-target, off-tumor toxicity in normal tissues, particularly in solid tumor indications. This presentation will review general considerations for developing T cell redirected therapies and walk through case examples to highlight specific challenges associated with these modalities. This includes tuning the binding affinity of each targeting arm to optimize preclinical efficacy and safety to try to maximize the therapeutic index for T cell redirected therapies.
mRNA-2752 is a mRNA-based LNP therapy containing three individual human mRNA sequences encoding OX40 ligand (OX40L) and two pro-inflammatory cytokines (interleukin 23 [IL-23] and 36γ [IL-36γ]). Following intratumoral administration, the three expressed proteins are intended to promote T cell co-stimulation to strengthen adaptive anticancer immune responses and cytokine/chemokine mediated inflammatory responses in the tumor microenvironment. Currently, mRNA-2752 is in Phase 1 clinical trials for advanced or metastatic solid tumor malignancies or lymphoma as a monotherapy or in combination with an immune checkpoint inhibitor, durvalumab. The nonclinical safety strategy to enable the mRNA-2752 IND and justification for the FIH dose will be presented.
As the I-O approach for cancer treatment continues to evolve, so do the methodologies to test the immunotoxic potential as well as pharmacodynamic (PD) properties of I-O therapeutics. The specific assays implemented to characterize the PD and potential immunotoxicity of I-O therapeutics in toxicology studies must be selected on a study-to-study basis. Several case studies are described to highlight the different strategies used to characterize the immunotoxic and PD activity of I-O therapeutics in FIH-enabling toxicology studies. In addition, the importance and appropriate selection of antigen challenge in order to fully assess the impact of I-O therapeutics on immune functions in the absence of a pharmacologically relevant tumor model are discussed as part of the case studies. Results from these FIH-enabling studies provide critical information to ensure safety as well as efficacy of I-O therapeutics for patients.
This presentation will review the current, general expectations for submission of nonclinical data to support FIH Investigational New Drug applications (INDs) for immuno-oncology drugs provided to the Center for Drug Evaluation and Research. Unique aspects of reviewing immune modulating drugs will be addressed, including using a minimally anticipated biological effect level (MABEL) approach, potential for cytokine release and immune-related adverse events, and evaluating combinations. After this overview, several examples will be given of INDs for immuno-oncology drugs that were allowed to proceed with no or minor revisions versus INDs that were placed on hold because of data deficiencies. The types of data that were considered when making a final determination of the acceptability of the proposed starting dose will also be discussed.
Session Chairs: Bert Haenen, Janssen Research and Development, Beerse, Belgium;
and Steven Bulera, Charles River Laboratories, Reno, NV
Rats are the preferred rodent species for nonclinical safety testing of candidate medicines, with either the Sprague Dawley rat or the Wistar Han rat as the predominant outbred strains used for this purpose. Each strain has its own gene package and consequently its own historical background data on, for example, growth rate, hematology, clinical pharmacology, and tumor incidence. By choosing either strain of rat, drug development companies make a strategic choice that is determined by factors such as type of drug or availability of historical background data in either strain. In the last 10 to 15 years, it appeared that a reduced long-term survival of Sprague Dawley rats was noted, which made especially US-based pharma companies reconsider the use of SD rats for their rodent development program. However, switching from one strain to another has major consequences in terms of drug metabolism, reproductive performance, and tumor incidence, for example. This Symposium will focus on the preservation of genetic heterozygosity and limitation of strain genetic drift, as well as the potential causes for reduced long-term survival of SD rats. In addition, the differences in historical background data of either strain will be highlighted, as will how these differences can impact the performance of either rat strain in DART or in carcinogenicity studies. The Symposium will conclude with lessons learned from strain differences in regulatory submissions.
The Charles River CD® IGS, Crl:CD(SD), rat has been the principal rat model used in nonclinical toxicity testing programs in North America and Japan. In Europe, the Wistar Han has been used as the primary rat model for nonclinical testing programs. At Charles River, production of these two outbred rat stocks utilizes an international genetic standardization (IGS) quality program to preserve genetic heterozygosity and to limit colony genetic divergence (drift). This presentation will review the IGS program utilized with the Crl:CD(SD) and Crl:WI(Han) models, including a centralized foundation colony and migration of genetics between production colonies. Efficacy of the IGS quality system has been assessed using a 240 SNP panel. Comparison of observed and expected heterozygosity (Ho and He, respectively) varied minimally among global colonies and the central foundation colonies for both stocks, indicating random mating. Additionally, the fixation index (FST), a measure of genetic differentiation between colonies, averaged <0.05 for both stocks, indicating that genetic divergence between colonies was minimal. Together, these data suggest the observed changes in survivability and earlier tumor onset of the CD IGS rat model are primarily due to environmental variables. While the precise cause(s) is not known, several husbandry changes were implemented over the past 10+ years—including changes to housing systems, adoption of social housing, dietary changes, and refinement of humane endpoints—that could affect use of this model. A review of the effects these parameters have on survivability and tumor incidence and onset will be provided.
A comparison of the Crl:CD(SD) rat (or CD®IGS rat) and the Crl:WI(Han) rat (or Wistar Han rat) will be presented in terms of general in-life parameters; non-neoplastic histopathology findings; neoplastic histopathology findings; survival, particularly in two-year carcinogenicity studies; and the use for reproductive and developmental toxicity testing. The two strains are generally comparable in terms of handling, but the CD®IGS rats are physically larger with a more rapid growth rate, requiring more test article compared with Wistar Han rats, while allowing collection of greater blood volumes. There is a notable difference between the strains in long-term survival, with the survival of CD®IGS rats declining from 2006 to the present. Currently, less than 20% of CD®IGS rat carcinogenicity studies complete the intended 104 weeks of dosing at Charles River facilities, while two-year studies in Wistar Han rats at Charles River routinely complete 104 weeks of dosing. Examining major neoplastic causes of death, the incidences of mammary neoplasms and pituitary neoplasms are greater in CD®IGS rats and the neoplastic onset is earlier in CD®IGS rats compared with Wistar Han rats. Reproductive and behavioral parameters are generally similar, with good fertility in both strains. Litter sizes are smaller in the Wistar Han rats and the spontaneous incidences for fetal malformation and variations are distinctly different. Mindful of these differences, the choice of rat strain used in a drug development program should reflect the specific needs and ultimate objectives of the Sponsor. Specific recommendations for strain use will be also be presented.
The rat is one of the two species that are generally used to conduct nonclinical safety studies during drug development. Within this species, either the Sprague Dawley or the Wistar Han strain are most commonly used. Usually, the Sponsor builds historical control data and expertise with only one specific strain and uses that as the default strain for all toxicology studies for various programs. However, based on scientific justification, a decision may be made to switch the rat strain for a specific program or to change the default rat strain. Any differences in handling, clinical pathology, and histopathology parameters between strains need to be well understood. Also, consideration needs to be made for strain-specific differences in endpoints measured in safety pharmacology, reproductive, general, and genetic toxicology studies. The metabolism profile can be different in the two strains, and hence, it is recommended that early DMPK (distribution, metabolism, pharmacokinetic) studies be conducted in the same strain as that being used for subsequent toxicology studies. This presentation will focus on a pharmaceutical company’s perspective on choice of rat strain and challenges and considerations for adopting a new rat strain.
Since ICH does not prescribe the use of a specific strain for toxicology studies in rats, regulatory agencies review data generated from Sprague Dawley, Wistar, and other strains of Rattus norvegicus. The Sponsor’s choice of a specific rat strain may be driven by pricing, availability, or regional preferences, but it is always consequential since toxic effects vary by strain. For example, the carcinogenic activity of nongenotoxic chemicals in rodents is characterized by a high degree of species, strain, and target organ specificity. This talk will discuss lessons learned from strain differences in regulatory submissions, including differences in survival, carcinogenicity, and reproductive performance. Case studies will be used to demonstrate the impact of these differences on regulatory decisions.
Session Chairs: Kevin Snyder, US FDA, Silver Spring, MD;
and Mark Carfagna, Eli Lilly and Company, Indianapolis, IN
Educational Support Provided by:
The Standard for Exchange of Nonclinical Data (SEND) is a standardized format for capturing a wide range of toxicology study data for Sponsor submissions to the US FDA. The implementation of the SEND model represents a tremendous opportunity for the application of large-scale data analytic approaches to nonclinical toxicology data. Recognizing this opportunity, the BioCelerate consortium, in collaboration with the US FDA Center for Drug Evaluation and Research (CDER), the Pharmaceutical Users Software Exchange (PHUSE), and the eTRANSAFE project, has initiated workstreams that focus on enabling these analytic approaches with an end goal of improving success and decision making in the early clinical development space. This forum aims to bring together members of industry, consortia, and regulatory bodies to discuss further opportunities for harmonization and utilization of SEND datasets. The broad and essential further value of SEND datasets in toxicologic research is in effective cross-study analysis. However, given the uneven implementation of the SEND model, it is currently a challenge to conduct highly efficient cross-study analyses to answer toxicologic questions. Presenters will share their experiences addressing challenges encountered in analyzing datasets from multiple studies, as well as their suggestions for how to harmonize implementation of the SEND data standard to enable robust, efficient analytic approaches, and publicly available, open-source algorithmic solutions to overcome current harmonization issues and perform cross-study analyses of SEND datasets. The forum will also give attendees an opportunity to provide input on the perceived value, challenges, and opportunities associated with analysis of toxicology data with large-scale data analytics.
Evolution of strategies to analyze and visualize SEND data has occurred during implementation of the SENDIG. Initially, SEND computational efforts were highly focused on collecting data and populating variables and domains. Over the past few years, the number of toxicology studies in SEND format has increased significantly. Scientists are now able to query multiple SEND datasets simultaneously to evaluate specific questions (i.e., use cases). This presentation will provide examples of data queries for cross-study analysis and identify areas for improvement. In addition, examples of routine analysis of individual SEND studies that can facilitate interpretation to provide insights beyond those gleaned from word processing–based reports will be discussed. Emphasis will be on strategies to utilize SEND data to improve safety assessment in drug development.
Control articles and vehicles used in toxicology studies are often complex mixtures. To determine the potential effects of vehicle components, it would be helpful to search SEND repositories; however, such searches are difficult because the description of vehicles in SEND today is a free-text field. To address this need, BioCelerate collaborated with US FDA and PHUSE to evaluate several ways vehicle information could be exchanged in a more structured way using SENDIG v3.1. These options were shared with CDISC to evaluate which might have the best chance of adoption in future SENDIG versions and sent as a survey to the SEND community to evaluate the best three options. This presentation will summarize the results of this survey, the PHUSE white paper describing their recommendation for exchanging vehicle information in SENDIG v3.1, and the status of the CDISC SEND team’s activities in preparing improvements for future SENDIG versions.
Although harmonization of implementation of the SEND data standard will lead to marked improvements in the usability of SEND datasets, this process will take significant time, and algorithmic solutions to harmonization issues can be applied immediately to solve some of the current harmonization problems. Through collaboration among US FDA, BioCelerate, and PHUSE, methods to implement these algorithmic solutions have been published in manuscripts and have been implemented as open-source software solutions. Specifically, a package, sendigR, is being developed using the statistical programming language, R, to facilitate cross-study analyses of SEND datasets. The package will include an R Shiny application with a graphical user interface, which will allow users who are not familiar with the R programming language to perform cross-study analysis. R programmers, on the other hand, will be able to use the package to develop their own custom cross-study analyses and will even have the opportunity to contribute source to add and improve upon the package’s functionality.
Detection of treatment-related effects in nonclinical toxicology studies can be difficult, as these studies tend to be grossly underpowered while assessing a wide range of endpoints. Comparison of the magnitude of a potential treatment effect against the range of variation measured historically among control animals is commonly used to adjudicate whether a true treatment-related effect was observed; however, relevant historical control data are not often readily available, and performing this comparison can be practically difficult. Fortunately, historical control ranges can be extracted from cross-study analysis of SEND datasets and formally integrated into the assessment of treatment effects in toxicology studies via application of Bayesian inference. The following topics will be discussed: (1) when it is appropriate to use historical control data; (2) why the Bayesian approach is preferred for incorporating historical control data; and (3) demonstration of a Bayesian model assessing treatment effect using historical control data via an open-source R Shiny web application.
The failure to detect possible safety signals in nonclinical studies for compounds that subsequently fail in the clinic is both frustrating and costly. Translational safety assessments of nonclinical studies against pooled clinical and nonclinical data from across industry can provide an early warning to stop the development of compounds that are likely to fail. This discussion evaluates the eTRANSAFE data sharing infrastructure in terms of its suitability for the comprehensive analysis of both the correspondence and the validity of animal data to human safety by focusing on (1) the challenges of developing a system that combines data across the nonclinical and clinical domains; (2) relating SEND-compliant study data to observations within clinical studies and from other nonclinical databases; and (3) analyzing and visualizing study data formatted in SEND (including digitized study report outcomes in a SEND-like structure).
Session Chairs: Shawna Weis, Constellation Pharmaceuticals, Inc., Cambridge, MA;
and Janice Lansita, ToxAlliance, Kennett Square, PA
Embryo-fetal toxicity studies are conducted during clinical development to support inclusion of women of childbearing potential in clinical trials and to support labeling for the approval of a marketing application. For biopharmaceuticals, which frequently lack activity in the rodent, the nonhuman primate (NHP) is the standard model to evaluate embryo-fetal toxicity. The conduct of these studies has become increasingly challenging due to the small number of facilities capable of performing them and a shortage of sexually mature monkeys. In addition, the low number of animals per group and the high rate of spontaneous abortion in cynomolgus monkeys can complicate interpretation of the data. To expedite the development of biopharmaceuticals for the treatment of patients with advanced cancer, recent US FDA guidance has proposed a weight of evidence (WoE) approach to support product labeling for reproductive toxicity. The following are among the considerations recommended to determine the appropriateness and content of a WoE approach to support product labeling for embryo-fetal risk: known class effects in humans; findings from genetically modified animals with or without drug administration; information from surrogate compounds; literature-based assessments about the biological role of the intended target in development; and the anticipated exposure during embryo-fetal development. Several recently approved oncology compounds, and others intended for non-oncology indications, have utilized an alternative approach for the evaluation of embryo-fetal risk. This session will explore the conditions under which an alternative approach may be appropriate to support product labeling for reproductive risk and how Sponsors can best justify the use of this approach.
Because biologics often lack activity in the typical animal models for reproductive and developmental toxicity evaluations, rodents and rabbits, the species of choice for assessing embryo-fetal risk with a biotherapeutic is often the nonhuman primate. However, these studies in nonhuman primates are challenging to conduct given the limited availability of sexually mature animals. This session will explore the scientific considerations for selection of alternative reproductive toxicity models and provide examples of how transgenic, knock-in, and knockout animal models and surrogate molecules can be used to support the nonclinical hazard assessment for various biotherapeutics. These approaches can provide a WoE argument allowing clinical trials to progress by addressing issues including the development of anti-therapeutic antibodies.
NHPs are recommended for evaluating effects on reproductive toxicity for biopharmaceuticals that are only pharmacologically active in NHPs. In assessing reproductive and developmental toxicity, while NHPs have similar placentation to humans, the need for conducting an NHP study can be discussed due to disadvantages in the interpretation of the results (e.g., small group size, limited dose group, insufficient historical control data) and animal welfare considerations. This session will discuss the PMDA perspective on the need for reproductive/developmental toxicity studies using animals for biopharmaceuticals based on our experience in consultations and reviews conducted in PMDA to date. A set of hypothetical case studies will be presented that illustrate conditions under which embryo-fetal risk was adequately characterized by a WoE approach. This session will also discuss the considerations in conducting reproductive/developmental toxicity studies in NHPs.
This presentation will discuss the MHRA perspective on the use of alternative reproductive toxicity models for biotherapeutics. A set of recent case studies will be presented that illustrate conditions under which embryo-fetal risk was adequately characterized using alternative models. This session will also discuss the conditions under which a study in the monkey might be needed if data from an alternative model were at odds with theoretical risks.
This presentation will cover changes in the regulatory landscape surrounding the assessment of embryo-fetal developmental (EFD) toxicity of biologics that have occurred since the 2011 adoption of the R1 revision of ICH S6: Guidance for Industry—Preclinical Safety Evaluation of Biotechnology-Derived Pharmaceuticals. Since adoption of ICH S6(R1), US FDA has published finalized regional guidance regarding the developmental and reproductive assessment of pharmaceuticals intended to treat advanced cancer (“Guidance for Industry—Oncology Pharmaceuticals: Reproductive Toxicity Testing and Labeling Recommendations”), and the finalized US FDA guidance “ICH S5(R3): Guidance for Industry—Detection of Reproductive and Developmental Toxicity for Human Pharmaceuticals” was implemented in the United States. While ICH S6(R1) placed significant emphasis on preference for testing the clinical candidate in the nonhuman primate (if the only available pharmacologically relevant model), the two more recent guidances suggest greater acceptance of alternative methods (surrogate molecules, genetically modified animals, etc.) and WoE analyses in the EFD assessment for pharmaceuticals. Case studies will be presented to help illustrate scenarios under which CDER has accepted a WoE approach or non-NHP animal models for the assessment of EFD endpoints for therapeutic proteins.
Session Chairs: Owen McMaster, US FDA, Silver Spring, MD;
and Michelle O. Kenyon, Pfizer Inc, Groton, CT
Nitrosamines are found in some foods, drugs, detergents, plastics, cosmetics, and industrial chemicals. This is of concern because many nitrosamines are carcinogenic in animals at low doses and after brief exposures, including after a single dose. Fried chicken, fried bacon, and rendered pork/bacon fat are among the meat and poultry products with the highest nitrosamine levels. N-nitrosodimethylamine (NDMA), N-nitrosopiperidine (NPIP), and N-nitrosopyrrolidine (NPYR) were the most frequently identified volatile N-nitrosamines in processed meat and poultry. In July 2018, US FDA announced the voluntary recall of several drug products containing the angiotensin II receptor blocker valsartan, due to high levels of NDMA. Since then, NDMA and other nitrosamines have been detected in other drugs. US FDA has taken steps to address the presence of nitrosamines in drugs, including the publication of a Guidance for Industry that includes recommendations for identifying and eliminating nitrosamine impurities from drug products. US FDA has also requested that some manufacturers withdraw certain approved drugs from the market. Since carcinogenic potencies for nitrosamines span about four orders of magnitude, Pfizer has classified nitrosamines of concern into 12 generic structural groups after carcinogenicity data for nitrosamines in each structural class were critically reviewed and conservative acceptable intakes (AI) derived for each structural group. This Symposium will discuss the evidence for nitrosamine carcinogenicity, the presence of nitrosamines in foods and drugs, the US FDA response to these findings, and Pfizer’s approach for the derivation of AI for potential drug product nitrosamines.
In the second half of the last century, comprehensive knowledge was accumulated about the carcinogenic N-nitroso compounds (NOC). This encompassed systematic research on structure-activity and dose-response relationships, molecular mechanisms of action, and biotransformation pathways in vitro and in vivo. In addition, profound knowledge of biological effects and underlying mechanisms of action were complemented by comprehensive dosimetry of human exposure via a variety of environmental exposure pathways. NOC formation was found to invariably occur under conditions where nitrosating agents encounter N-nitrosatable compounds (NNC). Conditions governing the extent of NOC generation in a variety of environmental settings have been elucidated. In addition to exogenous exposure, endogenous NOC formation in the organism has also been discovered as a potential human health risk. Biomarker-based research has shown that nitrosating agents are physiologically generated in the organism. As a potential consequence, uptake of N-nitrosatable precursors, including relevant drug molecules and/or food constituents, may result in endogenous NOC formation. Drug manufacturers should exercise due diligence and scrutinize production technology from chemical synthesis, formulation, and packaging to storage to mitigate contamination with NOC. In addition to NOC contamination of drugs, the risk of potential NOC formation in the organism may also need to be assessed.
Nitrosamines occur in a wide variety of foods, and the most commonly encountered nitrosamines in meat and poultry products are NDMA, NPYR, NPIP, N-Nitrosodibutylamine (NDBA), and N-Nitrosodiethylamine (NDEA). Nitrosamine levels in foods vary according to several factors, including food preparation and preservation techniques. Nitrosamines can form during storage or preparation, when nitrites (used to preserve meats) react with secondary or tertiary amines. Researchers have found a positive correlation between the levels of certain nitrosamines (NPIP, N-nitrosohydroxyproline [NHPRO], N-nitrosoproline [NPRO], N-nitrosothiazolidine-4-carboxylic acid [NTCA], and N-nitroso-2-methyl-thiazolidine-4-carboxylic acid [NMTCA]) and the amount of nitrite added to cooked pork sausages. The addition of erythorbic acid inhibited the formation of NHPRO, NPRO, NPIP, and NTCA, but increasing the black pepper content increased the levels of NPIP and NMTCA. Nitrosamine formation is also enhanced by high temperatures such as frying. Fried bacon contains 27 times the amount of total nitrosamines compared with microwave-cooked bacon. This presentation will provide a detailed look at our exposures to carcinogenic nitrosamines in our daily lives.
N-nitrosamine impurity levels in pharmaceutical drug substances and products are guided by the ICH M7 Guideline stating that the Threshold of Toxicological Concern (TTC) may be used to generate a toxicity limit, or a class-specific limit may be applied depending on the type of structural alert. The EMA, US FDA, and other regulatory agencies around the world have set provisional daily AI limits for N-nitrosamines based upon rodent carcinogenicity TD50 values for experimentally measured N-nitrosamines; where no experimental data exist, close analogs or a class-specific TTC may be used. To address whether N-nitrosamine carcinogenicity can be better predicted for regulatory purposes, an ad hoc work group of over 20 companies and universities has been established to address several scientific and regulatory issues. These include identification of N-nitrosamine mutagenicity and carcinogenicity reaction mechanisms, collection of all relevant experimental data, development of structure-activity relationships (SARs) consistent with mechanisms, identification of N-nitrosamine carcinogenicity potency categories from SARs, and more precise methods for calculating AI limits for N-nitrosamines based upon mechanistic analogs. This presentation will describe this collaboration and review our progress toward development of mechanistically robust SARs. Additionally, we propose an alternative approach to make the risk assessment of N-nitrosamines more precise by first establishing the dominant reaction mechanism before retrieving an appropriate set of close analogs. The TD50 of the most relevant analog from this set may be used for calculating AI limits. Barring that, an established default TD50 value for the analog group may be used.
In 2018, some carcinogenic nitrosamines were discovered in some Sartan drug products, leading to a regulatory requirement for pharmaceutical companies to evaluate all commercial active pharmaceutical ingredients (APIs) and drug products for nitrosamine risk by March 2021. Although nitrosamines are recognized as cohort of concern carcinogens, which are more potent than other non-nitrosamine carcinogens, carcinogenic potencies for nitrosamines span about four orders of magnitude. The establishment of appropriate limits is a crucial step in the risk assessment, and the use of read-across is the accepted methodology for compounds with no specific limits. Due to the large number of complex nitrosamines in Pfizer’s portfolio that required assessment in a short period of time, we took a pragmatic approach and classified nitrosamines of concern into 12 generic structural groups. Available carcinogenicity data for the nitrosamines in each structural class were critically reviewed and a conservative AI was derived for each structural group. The outcome of this structural grouping will be shared, and there will be a discussion regarding how the AI are utilized to guide analytical testing. This presentation will also explore situations where a focused read-across on a specific nitrosamine of concern can be valuable, and a case example of a compound-specific read-across will be shared.
Considerable attention is currently focused on the nitrosamines because a number of drugs contain levels of nitrosamines above the limits recommended by ICH. Angiotensin II receptor blockers (ARBs), ranitidine, nizatidine, and metformin were among the first affected drugs to be identified, but it quickly became clear that nitrosamine impurities could exist in other drugs produced by processes and materials that may produce nitrosamine impurities. US FDA and other regulatory bodies immediately conducted a detailed analysis of these impurities in affected drugs. In 2020, US FDA published a Guidance for Industry: “Control of Nitrosamine Impurities in Human Drugs.” This guidance provides information about the potential causes of the nitrosamine impurities in the APIs and other possible sources of nitrosamine contamination of drug products. The guidance also explains the AI limits for various nitrosamines, and API manufacturers are encouraged to optimize the design of the manufacturing processes for APIs to minimize the formation of nitrosamine impurities. Drug product manufacturers are encouraged to include testing procedures to ensure manufacture of drug products without unacceptable levels of nitrosamine. The guidance also shares details of the validated laboratory methods of the US FDA for assaying nitrosamine impurities in drugs as well as the analytical results for a number of drugs. This talk will discuss the US FDA response to the detection of nitrosamine impurities in drugs, including a discussion of the Guidance for Industry.
Session Chairs: Katie Sokolowski, CDER/US FDA, Silver Spring, MD;
and Drew Badger, DAB Consulting, Palm Springs, CA
This is a joint session between the ACT Early Career Professional Subcommittee and the American Board of Toxicology (ABT) and will be divided into three sections. The first speaker will provide background on and an overview of the ABT and the value of certification to early career toxicologists. The session will be interactive and is designed to answer questions from the audience. The second section will address sample questions with audience participation. Example toxicology questions and answers will be presented to the audience, along with tips for test-taking strategy. Audience participation will be strongly encouraged. In the final section, recently certified and recertified ABT Diplomates will join for a panel discussion on their exam experiences, strategies for preparation, and utility of the certification for career advancement, while answering additional questions from the audience.
The intent of this presentation is to understand the utility of the ABT credential and to prime participants for the pragmatic considerations for test preparation and recertification with the new computer-based testing centers. This presentation will open with the history, vision, and mission of ABT. This presentation will also cover the practice analysis study performed to identify the knowledge required for general toxicology and how the results of this study informed the revised ABT Certification Examination. Finally, the presentation will discuss practical considerations, including eligibility criteria, test site locations, recertification criteria, and available resources. The format for this presentation will be informal discussion allowing for audience questions throughout the presentation.
In this section of the Workshop, a series of sample toxicology questions will be presented to the group. Questions will be selected to represent all domains covered by the ABT exam (I. Design, Execute, and Interpret Toxicology Studies; II. Descriptive Toxicology: Environmental, Clinical, Non-clinical, and Forensic Investigations; III. Mechanistic Toxicology; IV. Risk Assessment). Participants are encouraged to actively participate through voting buttons that tally group responses for each question. Voting buttons can easily be implemented with online platforms or, if at an in-person meeting, with applications downloaded onto a personal device. The intent of this section is to provide a refresher to participants on test-taking strategies and dissect the anatomy of questions, as well as address general toxicology topics.
In this final section of the Workshop, a total of six panelists representing a variety of sectors will discuss their experiences with the ABT exam and certification. Half the panelists will be recent Diplomates who are able to comment on the revised exam. The other half of the panelists will be Diplomates who took their initial exam in 2000–2002 and had the opportunity to recertify their credentials. Recent Diplomates will share advice on how they prepared for the exam (i.e., intra-/extramural study groups, the ABT app, texts and other reference materials, or preparatory courses), if these strategies were effective, and their general experiences days before the exam and taking the exam. More senior Diplomates will share how the certification influenced their career development, if they would recommend taking the exam, and why they decided to recertify. The audience is encouraged to ask questions and stimulate discussion. Candidates will be contacted if the proposal is accepted.
Session Chairs: Simon Authier, Charles River Laboratories, Laval, QC, Canada;
and Shawna Jackman, Charles River Laboratories, Shrewsbury, MA
Educational Support Provided by:
After the first US FDA approval in December 2017, adeno-associated virus (AAV) vectors have emerged as a leading delivery method for gene therapies across a range of therapeutic indications and dosing routes. With the growing number of preclinical programs and also clinical trials using AAV vectors, strategies and practical considerations related to AAV vectors are evolving. Immunogenicity is an important AAV vector consideration, as pre-existing immunity may interfere with vector distribution and consequently alter transduction and transgene expression. With a number of AAV serotypes currently used in gene therapy, the presence of AAV antibodies in most humans, and varying seronegative incidences in nonhuman primates from diverse origins, particular attention needs to be paid to immunogenicity in preclinical safety models and translation to the clinic. This session will present critical considerations related to dosing product characterization, nonhuman primate supply logistics, AAV neutralizing antibody assays, and study design considerations. Study endpoints relevant to AAV will be discussed in the context of combined pharmacology, biodistribution, and toxicology studies. To conclude, regulatory perspectives on developing AAV vectors will be presented.
Development of AAV-based gene therapy vectors holds tremendous promise to address the unmet medical needs of genetic and complex diseases. In addition to rapidly emerging AAV technology that is helping to advance potentially transformative vectors, many lessons have been learned from the successes and failures of preclinical and clinical gene therapy programs. Here, key preclinical considerations, challenges, and advances in the discovery of AAV-based gene therapy candidates will be reviewed. Utilizing animal models of disease, strategies to achieve cell type–specific transduction, and understanding immunological or other biological barriers to gene therapy will also be discussed. Acknowledging specific challenges, thoughtful planning, and careful attention to analytical details can help guide the discovery of successful next-generation genetic medicines.
Genomic medicines offer great promise for correction of genetic diseases. These novel advanced therapeutics include AAV-based gene therapy, gene regulation, and genome-editing strategies, focused on different cell targets (in vivo or ex vivo) and delivery methods. Assessing the nonclinical safety profile of these medicines before first-in-human studies and during clinical development requires blending traditional toxicology expertise with molecular biology using a set of new tools to assess mechanisms of action at the genome level. A case-by-case assessment is most often needed. This presentation will discuss nonclinical considerations for safety assessment of novel genomic medicines delivered to target cells.
Selection of nonhuman primates (NHP) with no neutralizing antibodies (NAb) to the specific AAV vector in question in a preclinical gene therapy program is one of the biggest challenges. This is complicated for serotypes with higher prevalence (e.g., AAV2). This talk will provide an overview on the importance of this screening process and some technical aspects of developing appropriate NAb assays focusing on AAV2 and AAV9. Some of the critical NAb assay components include reporter vector, positive control, negative serum lots, and determination of a cut point. Understanding the challenges while openly discussing best practices and successes will allow for improved development and use of AAV NAbs going forward.
This presentation provides an overview of US FDA/CBER/OTAT regulatory review principles and preclinical development considerations for AAV-based gene therapy products.
Session Chairs: Chris Sheth, Aclairo Pharmaceutical Development Group, Inc., Vienna, VA;
and Hideo Fukui, Axcelead Drug Discovery Partners, Inc., Kanagawa, Japan
Educational Content Provided by:
ACT Outreach and Program Committees in collaboration with the Japanese Society of Toxicology
SARS-CoV-2 infectious disease (COVID-19) emerged as a highly transmissible agent, resulting in the need for a rapid assessment of existing antiviral interventions and new product development to combat the infection and prevent the spread of disease. Various Sponsors across a gambit of product areas and modalities have leveraged their abilities to bring some promising treatments to bear. This Symposium will provide an overview of vaccine and nonvaccine therapeutic interventions for COVID-19. The audience will learn about modern safety testing of vaccines and advanced cell and gene therapies and hear about the development and success of Remdesivir (a small molecule antiviral drug).
In 2020, two mRNA-based vaccines, encoding the full length of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein, were introduced for control of the coronavirus disease (COVID-19) pandemic. However, reactogenicity to the vaccine formulation remains and there is potential for enhanced disease by anti-N-terminal-domain (NTD) of the spike protein. Here, we optimized a lipid nanoparticle (LNP)–based mRNA vaccine candidate, encoding the SARS-CoV-2 spike protein receptor-binding domain (LNP-mRNA-RBD), which showed improved immunogenicity by removing reactogenic materials from the vaccine formulation and protective potential against SARS-CoV-2 infection in cynomolgus macaques. LNP-mRNA-RBD induced robust antigen-specific B cells and follicular helper T cells in the BALB/c strain but not in the C57BL/6 strain; the two strains have contrasting abilities to induce type I interferon production by dendritic cells. Removal of reactogenic materials from original synthesized mRNA by HPLC reduced type I interferon (IFN) production by dendritic cells, which improved immunogenicity. Immunization of cynomolgus macaques with an LNP encapsulating HPLC-purified mRNA induced robust anti-RBD IgG in the plasma and in various mucosal areas, including airways, thereby conferring protection against SARS-CoV-2 infection. Therefore, fine-tuning the balance between the immunogenic and reactogenic activity of mRNA-based vaccine formulations may offer safer and more efficacious outcomes.
As a result of the pandemic of SARS-CoV-2 infectious disease (COVID-19), more than 100 million people have been affected worldwide to date. To prevent its spread, COVID-19 vaccines are being developed using various modalities such as inactivated virus vaccines, mRNA vaccines, and virus-based vector vaccines. The Pharmaceuticals and Medical Devices Agency (PMDA) has taken several actions to facilitate vaccine development, and we recently released “Principles for the Evaluation of Vaccines against the Novel Coronavirus SARS-CoV-2,” which presents our basic principles concerning the efficacy and safety evaluation of COVID-19 vaccines in Japan. This session will discuss PMDA’s perspective on nonclinical assessment for the COVID-19 vaccine.
The emergence of the highly pathogenic coronavirus SARS-CoV-2 and its rapid spread leading to the coronavirus disease 2019 (COVID-19) pandemic has posed a serious global public health emergency. The ongoing pandemic has led to the development of several investigational cell and gene therapy (CGT) products as potential treatments of COVID-19. The conduct of a clinical trial for an investigational CGT product is guided by the Code of Federal Regulations (CFR) Title 21, Part 312, to ensure the safety and rights of subjects in all phases of a clinical investigation. According to 21 CFR 312.23(a)(8), the Sponsor is responsible for providing adequate pharmacology and toxicology data to support a conclusion that the proposed clinical trial is reasonably safe to conduct. This presentation will provide an overview of the regulatory review principles and preclinical development considerations for CGT products intended to treat COVID-19.
Veklury® (remdesivir, GS-5734TM), the first US FDA–approved antiviral for the treatment of COVID-19, is a single diastereomer monophosphoramidate prodrug of an adenosine analogue. It is intracellularly metabolized into the active triphosphate form, which in turn acts as a potent and selective inhibitor of multiple viral RNA polymerases. Remdesivir has broad-spectrum activity against members of the coronavirus family such as SARS-CoV-2, SARS-CoV, and MERS-CoV, as well as filoviruses and paramyxoviruses. The nonclinical safety and efficacy profile of remdesivir will be presented, including results of in vivo efficacy studies, off-target profiling, and repeat-dose toxicology studies.
Session Chairs: Grace Furman, Paracelsus, Inc., Leucadia, CA;
and David Serota, 7th Inning Stretch Consulting, LLC, Kalamazoo, MI
The work-from-home job force got a big push from the global coronavirus pandemic in 2020, but even before COVID-19 became a factor, the perceived freedom and flexibility of consulting has lured many a toxicologist away from full-time corporate employment. Regardless of your current stage of career development (early-, mid-, or late-career professional), if you’re considering a transition to consulting, this interactive Workshop, co-sponsored by the Roundtable of Toxicology Consultants (RTC) and Preclinical GPS, is for you! In a series of brief presentations, experienced consultants (RTC members) will tee up key topics that everyone is curious about and needs to think carefully about before embarking on a career as a consultant. Presentations will be followed by a 1.25-hour interactive Q&A session during which Workshop participants can ask questions in real time. Workshop participants will also have the opportunity to submit questions confidentially (in writing) during the 30-minute break. RTC panelists will be eager to share their unique perspectives on consulting as a career choice—all questions will be addressed! According to the 2019 RTC Business Practices Survey, approximately 15% of survey respondents are planning to retire completely in the next two to three years . . . and over 40% of respondents are considering reducing their consulting operations in the next two to three years. Is this the opportunity you’ve been waiting for? Do you have what it takes to make it as a successful consultant? Attend this Workshop and find out!
Transitioning away from a full-time position to life as a consultant can be scary! There are a lot of questions that you would need to consider before making the transition: How do you know if consulting is right for you? Is now the right time to make the transition? What services would you offer? Would you venture out as an independent or is joining a consulting group a better fit for you? What’s the difference? This presentation will provide you with a list of basic questions to consider when assessing whether (or not) consulting would be a good professional fit for you. Key content from the most recent (confidential) RTC Business Practices Survey will be shared to provide insight on what life as an independent consultant might look like for you, should you decide to break free! Workshop participants will have the opportunity to delve further into questions posed during this presentation during the interactive Q&A session in the second half of the Workshop. If you’re considering a career as a consultant but just don’t know how to get started, this presentation will help you get the ball rolling!
In this portion of the Workshop, you will hear information on different options for setting up your business structure, tax choices, hiring professionals, retirement planning, and insurance options. The age-old question will also be addressed: Is it acceptable to throw in a load of laundry while I’m working? The scheduled time for the talk may be brief, but the discussion after the break will be well worth waiting for!
Getting clients can be a daunting aspect of going out on your own as a consultant, especially for those of us that tend not to be extroverted. This discussion will highlight identifying potential clients, leveraging and expanding your existing network, and vetting prospective clients. Approaches that have worked and not worked will be described, as will soft marketing your skill set. Business development is a critical aspect of being a consultant and a lot less difficult than it appears from the outside. The online tools, university resources, and value of personal referrals will be described. Client expectations and personalities will also be covered to enhance repeat business.
Money does not buy happiness, but revenue keeps your consulting company operational. Key decisions for every consulting company are how much to charge for services and what services to provide. Almost all consultants charge an hourly rate. This is perfect for many consultants. In this presentation, you will learn some ways to set an hourly rate, what services are typically billable, how frequently to raise prices, and some hurdles to getting paid as a consultant. Because charging by the hour limits your income to the amount of time available, we will also discuss the more lucrative and value-based approach of billing on a project basis. You will learn how hourly and project-based work differ, why project-based work can pay more, and what projects are better suited for project-based work, as well as balance between project work and advisory consultation. Other topics will include how scope of services affects revenue, the value of an expanded team of consultants, and the value of operations in your consulting practice. We will also discuss why it is financially important to hire a team as early as possible to support legal, bookkeeping, accounting, and project management, as well as to provide other support.
Session Chairs: Dana Minnick, SciLucent, Inc., Cary, NC;
and Nicole Lay, SciLucent, Inc., Tucson, AZ
Educational Support Provided by:
Despite our best planning, most of us have experienced unexpected findings in safety studies that may require thoughtful navigation. Some findings may require investigative or new studies to clarify findings and/or a safe dose. Sometimes just having better data, such as having a better understanding of tissue pharmacokinetics/pharmacodynamics, may be needed. Or perhaps a more thorough assessment of the data on hand is needed to support safe use in humans. In this Symposium, we will highlight several case studies where unexpected safety findings in development programs triggered a course correction, as well as the strategies used to navigate a successful pathway to support clinical trials from both the Sponsor and the regulatory perspective.
This talk will give a brief introduction to the Symposium, highlighting some of the key messages from the individual talks in the session. Despite our best planning, most of us have experienced unexpected findings in safety studies that may require thoughtful navigation. In this Symposium, we will highlight several case studies where unexpected safety findings in development programs triggered a course correction, as well as the strategies used to navigate a successful pathway to support clinical trials from both the Sponsor and the regulatory perspective. Strategies to navigate through unexpected findings and key messages from the Symposium speakers will be highlighted in this introduction.
This talk with present key strategies for successful regulatory agency engagements when confronting difficult nonclinical challenges. Using examples of recent challenges with innovative biologics and molecules, the speaker will discuss how to manage the unexpected and still build a constructive interaction with regulatory reviewers. Plans are usually built around success, but being prepared for the unexpected is a necessary part of product development. When working with new technologies, this can be even riskier, as the paths are not as well trodden.
This session will focus on regulatory and scientific considerations for safety pharmacology issues that arise during drug development. QT prolongation, arrhythmias, seizures, and gastrointestinal alterations are often unexpected functional effects that require a holistic review of the program to build a path forward. This session will review essential considerations when managing these more common unexpected safety pharmacology findings. The evolving regulatory framework for safety pharmacology findings will be discussed and case studies will be reviewed to illustrate potential safety investigation strategies. Species selection, exposure/effect relationships, safety margins, and translational considerations will be highlighted against regulatory expectations that parallel clinical trial risk assessment requirements.
“External things are not the problem. It’s your assessment of them, which you can erase right now.”—Emperor Marcus Aurelius. Thyroid tumors or excessive mortality in a rat carcinogenicity study or tremors in a monkey study or abortions in a reproductive toxicology study may be indisputably linked to your drug candidate, but these don’t have to be showstoppers. In fact, these findings often provide an opportunity to conduct follow-up experiments to better characterize the toxicity or craft an assessment that could describe a potentially safe context of use for the drug under development. This presentation will provide case studies of unexpected nonclinical safety signals during drug development and the regulatory response to these assessments.
A nonclinical-based clinical hold may delay your clinical development, but it is the opportunity to consolidate your data for a robust and favorable safety assessment. Well-designed proof of concept studies are also necessary to support initiation of clinical studies. Two cases will be discussed illustrating the regulatory agency actions and responses from Sponsors. The first case study will describe a process-related genotoxic impurity out-of-spec that showed up after the Phase 1 in a research IND. The second case will describe an example of a drug with a less-than-favorable nonclinical package and lack of human data that the Sponsor proposed for treatment of patients with COVID-19.
Session Chairs: Saurabh Vispute, Pfizer, Inc, Groton, CT;
and Drew Badger, Capsida Biotherapeutics, Thousand Oaks, CA
The skin serves as a dynamic interface between the human body and the environment. As such, skin can manifest severe symptoms of disease originating not only from local stimuli, but also from systemically derived diseases such as psoriasis and atopic dermatitis. Because of the diverse array of dermatologic conditions, development of dermatological products can be uniquely complex and should include considerations of the anatomy, physiology, and pathological response of the skin as well as broad aspects of systemic biology. The purpose of this session is to provide the audience with an overview of skin biology and topical drug considerations, followed by a discussion of drug development strategies for local and systemically administered dermal products from an industry and regulatory standpoint. The first talk of this session will provide an overview of skin anatomy, function, factors affecting systemic absorption and elimination, formulations, and bioanalytical challenges for dermal products. The second presentation will emphasize methods to assess skin absorption, in vitro and in vivo models, and typical approaches for topical and systemic dermal product development. The next speaker will present examples of nonclinical development strategies and toxicological considerations for local and systemically administered compounds to treat dermal diseases. The final presentation will provide regulatory perspectives and case studies of dermal drug product development. Overall, the audience will gain a detailed understanding of nuances of dermal toxicology assessment and development strategy of compounds intended to treat dermal diseases.
This presentation will deliver a basic overview of skin biology, common toxicities observed clinically, formulation/CMC, and bioanalytical considerations. Skin anatomy, function, and factors affecting absorption will be discussed, as will exposure routes, formulation/CMC, bioanalytical challenges in exposure assessment, and applications in pharmaceutical and chemical/cosmetic industries. The talk will also provide a brief overview of skin conditions, types of toxicities, and reasons for developing dermal products.
This talk will present on current models and methods for assessing dermal efficacy and toxicity (both in vivo and in vitro), including animal and in vitro methods for dermal toxicity assessment and translatability to human. The current state of alternative models and regulatory acceptance status for pharmaceutical and nonpharmaceutical products will be discussed, and traditional “hazard ID” (BCOP or Buehler skin sensitization) will be compared with “risk assessment.” The presentation will also cover novel assays and methods for discovery screening and predictability/translatability of potential drug candidates.
This presentation will focus on nonclinical drug development strategy for dermal products, including a comparison of toxicology programs supporting topical and systemic dermal product development, toxicology programs supporting first-in-human clinical trials, and toxicology programs supporting market applications.
Case studies from a regulatory perspective will be provided, and potential regulatory discussions for navigating safety considerations of dermal product development will be considered.
Session Chairs: Lorrene Buckley, Eli Lilly and Company, Inc, Indianapolis, IN;
and Paul Brown, US FDA, Silver Spring, MD
Excipients are a major component of formulated drugs and play key roles in their effective delivery, stability, and PK. Novel excipients are used in the development of alternative routes of administration for special populations (e.g., pediatrics, geriatrics), oral (versus parenteral) delivery of biologics (e.g., permeation enhancers, peptidase inhibitors), and delivery of insoluble biologic materials (e.g., use of polymers). Although often considered “inactive ingredients,” excipients can contribute to the safety profile of the product. The safety and CMC characteristics of novel excipients are currently qualified within individual, proprietary NDA/BLA regulatory submissions; such information is not publicly available to support other uses by the scientific/drug development community. Further, regulatory guidance and industry experience relating to excipient development and qualification is relatively limited. In recognition of the challenges and barriers inherent in current regulatory pathways for qualification of excipients and with a desire to speed drug innovation, US FDA is developing a pilot program whereby novel excipients would receive US FDA review independently of an NDA/BLA submission. A novel excipient review program would allow companies to know in advance if a new excipient was acceptable from a regulatory view without running the risk of an IND, NDA, or BLA being rejected or delayed because of questions over a novel excipient. An industry survey of experience with novel excipients is planned, and case studies of novel excipient use and qualification will be described.
The talk will explain what novel excipients are and how and why they are used. Recent examples of applications of excipients in novel drug delivery systems will be described to demonstrate the increasing need for and value of novel excipients.
This talk will present general considerations for scientific approaches and regulatory guidance for safety qualification of novel excipients employed in drug product development. Current pathways for regulatory review/approval and challenges (lack of sufficient toxicology studies, availability of existing info, acceptability of read-across) will be described. The special topic of assessment of excipients in generic drug products will also be highlighted.
Based on a US FDA request for information (RFI), there was support for establishing a pilot program to explore an independent pathway for qualification of excipients. The possible pilot program would include the need for definition of context of use and adequate supporting information. Further details and considerations for the program need to be developed.
A generic drug formulation may differ from the reference listed drug (RLD) by containing other inactive ingredient excipients. These excipients must comply with the regulatory permitted uses and limits. When an excipient is used at levels, a duration, or a route of administration that differs from those listed, several approaches can be utilized to qualify that excipient. The first presentation of case studies will demonstrate several of these approaches. Two additional case studies will be shared that highlight the use of an abbreviated nonclinical package to support a new formulation of an approved product and the nonclinical package to support an oral enhancer agent.
Session Chairs: Gary Burleson, Burleson Research Technologies, Inc., Morrisville, NC;
and Patricia Ryan, AstraZeneca, Gaithersburg, MD
Educational Support Provided by:
Normally, virus-specific antibodies from an active infection or vaccination play an important role in the control of virus infections. However, in some instances, the presence of specific antibodies can be detrimental to the host due to antibody-dependent enhancement (ADE) of virus infection. ADE occurs when virus-specific antibodies interact with Fc and/or complement receptors in a manner that enhances the entry of a virus and/or the replication of a virus in the cells and worsen the disease. ADE has been reported both in vitro and in vivo for a number of viruses and can be of concern to disease control of these viruses via vaccination. This series of seminars will discuss the current understanding of the underlying immunology and mechanisms of ADE, introduce Dengue virus as a prototypical virus, provide some common characteristics of viruses causing ADE, discuss approaches used in the development of vaccines to minimize the risk for ADE, and provide a regulatory perspective on this important potential toxicity.
This introductory presentation will review the immune response and discuss enhancement mechanisms in viral infections.
Dengue virus, an enveloped positive strand RNA virus, is the prototypical virus causing ADE. This mosquito-borne flavivirus infects millions of people living in the tropical and subtropical regions of the world each year. Dengue virus vaccines have been developed to address this important disease. Dengue virus ADE is the best studied of ADE, and the pathology and mechanisms involved will be discussed. COVID risk of ADE will also be reviewed.
ADE is a general concern for the development of vaccines and antibody therapies since the mechanisms supporting antibody protection against viruses have a theoretical potential to worsen the infection or result in harmful immunopathology. This talk will discuss approaches used in the development of vaccines and antibodies to minimize the risk for ADE and provide some specific in vivo examples of evaluation of ADE in an influenza B rodent model.
The last presentation will provide a regulatory perspective on ADE toxicity and viral vaccines.
Session Chairs: Douglas Ball, D&B ChemTox, LLC, Southbury, CT;
and Douglas Donahue, Becton, Dickinson and Company (BD), Research Triangle Park, NC
Educational Support Provided by:
Becton, Dickinson and Company (BD)
The Medical Device Reporting (MDR) regulation contains mandatory requirements that manufacturers, importers, and device users must provide to the US FDA. The addition of a pharmacological agent (i.e., a medical device-drug combination product) may make registration somewhat more complex. This session was designed to help toxicologists navigate the registration process and provide a general understanding of the requirements to qualify medical device and medical device combination products. The first speaker will provide an overview of the recommended physical-chemical testing for US FDA submission of medical devices and combination drug products including best industry practices. The next two speakers will discuss the specific toxicological concerns for medical devices and combination drug products, respectively, including their common and unique risk assessment requirements. The final speaker will be from the US FDA and will discuss issues and recommendations for regulatory submission and common questions received during the regulatory submission process. The course will conclude with a panel discussion answering questions from the participants.
A number of analytical techniques are used to develop knowledge of the chemistry of the materials involved in container closures, medical devices, or packaging systems that are used during the life cycle of a pharmaceutical product. The ultimate higher-level end goal, however, is always to assess patient risk. Because of the incredible diversity of materials, their functions, and their purpose, a universal standardized single test to understand this risk is not possible. Fortunately, over the course of decades, a refined approach has been developed utilizing situationally adapted best practices and includes guard rails to aid the stakeholders in achieving their end goals. This presentation will discuss the analytical methodology in a manner appropriate for the process stakeholders who are not specialized analytical chemists. The governing regulatory guidelines will also be discussed, along with the informational content gleaned when using various analytical techniques. An example study will be shown, with a focus on the utility for the toxicologists of the data generated during each portion of work by the chemists.
The presentation will provide an overview of the approach used to conduct a toxicological risk assessment of extractables and leachables released from medical devices.
For a pulmonary medical device like a spacer for a metered dose inhaler, qualification focuses only on the product itself since it could be used to help facilitate the delivery of any number of drugs. With an external pulmonary medical device that is integral to delivering a specific drug product to a patient, the qualification takes on additional complexity. The qualification of such a combination drug product must include conducting not only appropriate In vitro and in vivo biocompatibility studies, but also a toxicological examination of the extractable profile of the device followed by a safety assessment of those that leach into the product stream resulting in patient exposure. The qualification of the extractables and leachables considers many critical safety endpoints (e.g., mutagenicity, irritation, sensitization, repeat-dose toxicity) in conjunction with various factors including dose, duration of exposure, route of administration, and the patient population. Such an assessment at the extractable stage supports analytical assay development for the leachable study, in addition to being a toxicological “window of opportunity” to identify potentially concerning chemicals before committing to further development. Thus, the combination of the appropriate biocompatibility studies and qualifying the leachable chemicals that patients will be exposed to when using the combination drug product ensures patient safety.
The intended use and product design should be considered in the safety evaluation of medical devices. For combination products, this includes considerations related to the drug constituent. In addition, for medical devices labeled for use with specific drug products, this includes considerations related to the specific drug product(s) for which the product is labeled. This talk will provide an overview of combination product regulation, including how combination products are defined and how center assignment is determined. Additionally, considerations and common issues regarding extractable and leachable studies for Center for Devices and Radiological Health–led submissions that include a drug constituent as well as drug delivery devices intended to deliver specific drug products will be discussed.
Session Chairs: Lyn Wancket, Charles River Laboratories, Durham, NC;
and Kirsten Crapnell, Becton Dickinson, Research Triangle Park, NC
Educational Support Provided by:
Medical device biocompatibility preclinical testing may seem deceptively simple when working with face masks and subcutaneous catheters, but what about relatively simple devices that cross multiple tissue spaces? This session will trace the path of a spinal needle throughout testing design, result interpretation, and risk assessment writing. Speakers from the US FDA and other organizations will discuss biocompatibility of a spinal needle. First, the in vitro testing (cell cytotoxicity, hemolysis, hemocompatibility) and in vivo testing (sensitization, irritation, implantation) suggested for the spinal needle will be discussed for traditional biocompatibility assessment. Next, advancements in the transition of in vivo sensitization testing to in vitro testing being developed to reduce animal testing will be discussed. Additionally, the interpretation of data from more complex biocompatibility in vivo tests (including pathology), the challenges of working with spinal needles that cross multiple tissues (skin, soft tissue, CNS), and crafting a risk assessment will be reviewed. Finally, a US FDA representative will review the Center for Devices and Radiological Health (CDRH) and suggest ways to interact with the agency. Performing biocompatibility testing and the steps outlined are necessary to determine the fitness of a device for human use and to see whether use of the device can have any potentially harmful physiological effects.
Medical device biocompatibility evaluations include both in vitro and in vivo testing. In vitro testing plays a key role, providing both screening as well as determinant chemical and biological information. The scope of biological testing, as governed by ISO 10993, includes evaluating medical device and device materials and their extracts for their effect on cells and whole-body biological pathways. This presentation will present an overview of in vitro and in vivo biological testing, with an emphasis on some of the more often performed testing: in vitro cell cytotoxicity, hemocompatibility, including hemolysis and clotting characterization using the Platelet and Leukocyte Count and the Partial Thromboplastin Time tests, in vivo acute systemic toxicity, irritation, and sensitization.
While in vivo testing has been the traditional focus of many biocompatibility tests, an emphasis on moving away from animal testing has opened new avenues for development and validation of new biocompatibility assays. This talk will cover some of the new advances (and potential pitfalls) of moving biocompatibility assays into in vitro models. The speaker will outline currently completed test models and identify assays that are promising for the near future. Specific considerations for the example spinal needle will be discussed, including factors such as irritation and pyrogenicity testing for products that cross multiple types of tissues during medical use. The speaker will also focus on the challenges of interpreting complex in vivo biocompatibility tests, including those with a pathology focus. Finally, the challenge of coordinating all the data for the example spinal needle together for a regulatory submission will be outlined, including a focus on drafting an effective risk assessment and ways to place the results to date in context.
This talk will provide an overview of the structure of the CDRH, the center within the US FDA with primary oversight of medical devices. The speaker will emphasize the most common routes for class II devices (like a spinal needle) and methods to interact with the agency and solicit feedback ahead of the submission. CDRH includes the office responsible for premarket review, the Office of Product Evaluation and Quality (OPEQ). Offices within OPEQ are grouped by clinical specialty or system (e.g., surgical and infection control devices; cardiovascular, neurological, and physical medicine; orthopedics) and subdivided into divisions that review specific device types with teams of interdisciplinary specialists. The CDRH presubmission program, which allows an applicant to obtain agency feedback before their regulatory submission, will be discussed.
Session Chairs: Marie Fortin, Jazz Pharmaceuticals, Hillsborough, NJ;
and Michael Santostefano, Merck & Co., Boston, MA
Clinical drug-induced liver injury (DILI) is poorly detected in nonclinical studies, and Merck & Co., Kenilworth, New Jersey, USA, has developed improved methods to identify compounds with hepatotoxicity risk in the early drug discovery process (Kang et al. 2020; Monroe et al. 2020). This Mini-Symposium will describe a new safety testing paradigm that relies on gene expression biomarker panels to readily identify drug-induced tissue injury and lower risk of DILI. This strategy has been incorporated into a toolbox of early screening assays used to de-risk safety liabilities before drug candidate selection. The gene expression biomarker panels can diagnose multi-tissue (liver, heart, kidney, and skeletal muscle) toxicity, as well as provide information on potential for reactive-metabolite mediated liver injury in humans. Gene expression changes in liver and other tissues allow for monitoring drug-induced tissue degeneration/necrosis (Glaab et al. 2020). This Mini-Symposium will describe a methodology used to identify potential clinical DILI risk, called the liver response assay (LRA), and its application to both early in vitro (rat or human) screens or in vivo rat studies. The presenters will describe the development and qualification of the gene expression panels and their use in a novel approach to de-risk drug candidates from early discovery in vitro screening to later in vivo before development candidate selection. The Mini-Symposium will also highlight how this novel approach has greatly reduced the attrition rate of compounds in later development.
This presentation will describe a rat liver transcriptional signature biomarker used to discern doses of drugs with bioactivation mediated hepatotoxic potential by measuring transcriptional pathways activated by electrophilic covalent reactive metabolites (CRM). We established this system using well-benchmarked CRM forming test agents and conducted an evaluation of this system using a well-curated list of commercial drugs and internal Merck & Co., Inc., Kenilworth, New Jersey, USA, compounds anchored in the clinical experience with respect to ADRs and hepatotoxicity. Based on 130 compounds run in short-term rodent studies and with consideration of the clinical dose administered, the approach yielded 33% sensitivity and 95% specificity for discriminating safe from hepatotoxic drugs. Additional qualification and refinement of these experimental models is ongoing with the growing confidence that they add important new information for guiding a weight of evidence approach that aids lead optimization and candidate selection. When used together with other strategies that can identify liver toxic liabilities resulting from other established mechanisms of DILI, overall DILI prediction sensitivity is expected to rise. Case examples explaining the strengths and limitations of the approach will be described.
This presentation will describe the translation of in vivo rat liver gene expression biomarkers of bioactivation (detailed in Presentation #1) to a resource-sparing and higher-throughput in vitro assay using an advanced micropatterned co-culture system (HEPATOPAC®) with rat primary hepatocytes. The in vitro assay was qualified for internal decision making using 90+ DILI positive and negative drugs and showed 81% sensitivity and 90% specificity in detecting hepatotoxicants. Using paired examples of compounds from distinct chemical series and close structural analogs, we demonstrate that this assay can differentiate drugs with lower DILI risk. The utility of this in vitro transcriptomic approach was also examined using human HEPATOPAC from a single donor, yielding 68% sensitivity and 86% specificity. Routine use of the rat model has been adopted, with deployment of the human model as warranted on a case-by-case basis. This in vitro transcriptomic signature-based strategy can be used early in drug discovery to de-risk DILI potential from chemically reactive metabolites by guiding structure-activity relationship hypotheses and candidate selection.
This presentation will describe the development, qualification, and implementation of gene expression signatures that diagnose tissue degeneration/necrosis. Leveraging microarray data, differentially expressed genes were discovered as being shared consistently across four prioritized tissues (liver, kidney, heart, and skeletal muscle), following injuries induced by known toxicants and so were termed “universal.” Quantitative PCR was used to down-select gene candidates that consistently and robustly responded to tissue injury. Mathematical algorithms were generated to convert each tissue’s gene expression fold change values for the 12 genes to a single metric, scaled between 0 and 1, and a positive threshold set. Performance determined by testing a set of approximately 100 additional rat studies resulted in approximately 90% sensitivity and 100% specificity. Bundled together, we have incorporated these gene expression signature panels into a four-day rat safety lead optimization toxicity study design, which provides a rapid objective assessment of compound liabilities without the necessity to perform time-consuming tissue microscopic histopathologic analyses and quickly identifies candidates with safety liabilities. The reduction in compound attrition in later stages of development will also be highlighted.
Session Chairs: Sucheta Mukherjee, Aligos Therapeutics, Inc., South San Francisco, CA;
and Ray Zhang, Theravance Biopharma, South San Francisco, CA
This Mini-Symposium is presented by the ACT Early Career Professional Subcommittee and is the latest iteration of the successful “What to Do When Things Go Wrong” series previously presented at the 2017 and 2019 annual meetings. What do you do when the fundamental way that you do work completely changes? Regardless of your discipline or job sector, the global COVID-19 pandemic has undeniably affected the way we work as toxicologists. This has created both new challenges as well as novel takes on familiar issues. To broadly understand the hurdles overcome by toxicologists in this new working paradigm, we will draw on the perspectives from a cross-section of speakers representing contract labs, industry, and the federal government. Case studies will include implementing virtual staff training and audits, developing novel therapeutics during the pandemic, and perspectives from a US FDA reviewer. After connecting these vignettes, common themes in the adaptations in research and drug development will be further reviewed in the Q&A portion of the Mini-Symposium. Through an interactive discussion between the audience and the speakers, we will aim to reflect on how certain changes catalyzed by the pandemic could start to define a new normal in a post-pandemic world.
When the COVID-19 pandemic started, the priority at our Contract Research Organization (CRO) was to ensure the safety of our staff and laboratory. Policies were put in place to prohibit visitors, our staff were provided essential worker badges, and work-from-home/staggered schedules were initiated. For the first month, this was acceptable, but as time went on, we needed to find ways to continue our interactions with Sponsors/Study Monitors and quality assurance auditors and to deliver specialized staff training. Virtual tools were developed to ensure business continuity, including a virtual vivarium tour, staff training, and hosting virtual audits. The aim of this presentation is to provide insight into how the pandemic changed how we work and interact at a CRO.
COVID-19 caused by the SARS-CoV-2 virus has become a global pandemic. 3CL protease is a virally encoded protein that is essential to the viral life cycle across a broad spectrum of coronaviruses with no close human analogs. We have designed a phosphate prodrug, PF-07304814, that is metabolized to active moiety, PF-00835231, which is a potent inhibitor in vitro of the coronavirus family 3CL pro, with selectivity over human host protease targets. The speaker will discuss the nonclinical safety strategy that enabled clinical studies with PF-07304814.
The COVID-19 pandemic and the associated public health ramifications have resulted in significant social and economic disruption around the world, including within the United States. The US FDA has been instrumental in responding to the crisis. This presentation will provide a firsthand perspective of day-to-day life as a reviewer within the agency throughout the pandemic and the multitude of challenges faced along the way.