Symposia and Workshops

Session Chairs: Maggie Liu, Pfizer Inc., San Diego, CA; and Judith Prescott, Merck & Co., Inc., West Point, PA 

Severely debilitating or life-threatening indications (SDLTs) include conditions in which life expectancy is short or quality of life is greatly diminished despite available therapies. As such, the medical context for SDLT indications is comparable to advanced cancer and the benefit versus risk assessment and development of SDLT therapeutics should be modeled on that for advanced cancer therapeutics. A streamlined development approach would allow patients with SDLTs earlier and continued access to new, potentially beneficial therapeutics. While there are regulatory guidelines for advanced cancer therapies and for therapies for rare diseases (which include some, but not all, SDLTs), as well as regulatory programs primarily employed to expedite late development for serious conditions, there is minimal, and no global, guidance to facilitate early development and availability of SDLT therapeutics for patients with limited therapeutic options. In light of this high unmet need, a global guideline is needed to facilitate streamlined development of non-oncology SDLT therapeutics. While much of this is focused on therapeutics for SDLT conditions, it should be noted that the development of vaccines for SDLT indications with urgent medical need and no adequate preventatives should similarly apply a streamlined approach. This Symposium will (1) introduce a proposed streamlined development approach for non-oncology SDLT conditions across therapeutic areas, (2) discuss potential criteria defining the scope applicable to global guidance, (3) discuss industry case examples of the development of COVID-19 vaccines and therapeutics during the current pandemic, (4) provide a regulatory perspective and description of current application of streamlined approaches for SDLT indications, and (5) incorporate patients’ perspectives on benefit/risk considerations when living with SDLTs.

1-1

Proposed streamlined development approaches for vaccines for SDLT indications and non-oncology SDLT small molecule therapeutics will be presented. For therapeutics, this proposed approach would allow rapid initiation of patient trials and continued treatment beyond the conclusion of the early therapeutic studies regardless of availability of nonclinical safety data, as well as elimination or deferment of nonclinical studies that are not considered essential to supporting patient safety given the high unmet medical need. This approach would allow patients with SDLT conditions earlier and continued access to therapeutics and increase the speed of progression through development. For both therapeutics and vaccines, these approaches would enable an early understanding of potential efficacy and allow patients or participants, in conjunction with their physicians, to make more informed decisions regarding potential initiation and/or continuation of treatment in the context of benefit versus risk considerations. This may additionally increase the SDLT indication therapeutic pipeline, directly benefiting patients and reducing the economic and societal burden of SDLT conditions.

1-2

A significant regulatory gap exists to facilitate global development of therapeutics for non-oncology SDLTs. In a 2017 publication, a streamlined approach to the development of treatments for SDLTs was proposed to facilitate earlier and continued patient access to new, potentially beneficial therapeutics. However, a major hindrance to broad adoption of this streamlined approach has been the lack of universally accepted, objective criteria to define SDLTs. This presentation is based on a 2019 publication that addresses the challenge of defining SDLT scope in order to stimulate broader discussion and facilitate development of regional, and ultimately international, guidelines on development of therapeutics for SDLTs. Key attributes of SDLTs and criteria for SDLT scope definition will be discussed.

1-3 and 1-4

The current COVID-19 pandemic and its resulting impact on patients, drug development, medical practice, and society at large have illustrated the urgency of streamlining nonclinical and clinical development for non-oncology SDLT conditions to ensure the timely development of therapies for patients with no adequate treatment options and for preventatives for high unmet medical needs. During this unprecedented time, it has been inspiring to see industry, regulators, other governmental agencies, and academics work together to develop treatments and vaccines in an expedited manner to meet this extremely urgent medical need. This session will feature industry case examples of the development of COVID-19 vaccines and therapeutics, including the nonclinical development approaches and interactions with regulatory authorities. Learnings from these experiences and how these may be applied more broadly to other SDLT conditions will be discussed.

1-5

In 2018, the US Food and Drug Administration (US FDA) issued a draft guidance for the nonclinical development of pharmaceuticals indicated for the treatment of Severely Debilitating or Life-Threatening Hematological Disorders (SDLTHD) other than cancer. The SDLTHD guidance includes diseases or conditions with potentially fatal outcomes, that cause major irreversible morbidity, and/or for which there are not existing effective treatment options. The nonclinical programs for SDLTHD indications are designed to be flexible, with the goal of facilitating entry into clinical trials and accelerating the development of promising pharmaceutical candidates while also protecting patients from unnecessary adverse effects and minimizing the use of animals consistent with the 3Rs (reduce/refine/replace). The Agency also issued two draft guidances in May 2020 to address challenges related to COVID-19: (1) a guidance to facilitate a sponsor’s preparation of, and the US FDA review of, a pre-investigational new drug application (pre-IND) meeting request, and (2) a guidance with recommendations to develop drugs with direct antiviral activity, immunomodulatory activity, or other mechanisms of action. The aim of this presentation will be to familiarize the audience with streamlining strategies already in practice by the US FDA to facilitate development and delivery of potentially life-changing therapies to patients with SDLT indications. Case examples and types of diseases or disorders that the Agency currently considers within the scope of the SDLTHD guidance will be presented and discussed.

Session Chairs: A Wallace Hayes, University of South Florida College of Public Health, Temple Terrace, FL; and Peter Pressman, The Daedalus Foundation, San Clemente, CA

E-cigarettes are battery-powered devices that generate an aerosol for inhalation by heating a liquid formulation (e-liquid) to temperatures ranging from 40° to 300°C, while most vaping products are not battery powered and may not require heating. In its 2018 report on Public Health Consequences of E-Cigarettes, the US National Academies of Sciences (NAS) stated that there is conclusive evidence that completely substituting e-cigarettes for combustible tobacco cigarettes reduces users’ exposure to numerous toxicants and carcinogens present in combustible tobacco cigarettes. However, given their relative novelty, conclusive long-term clinical studies on the health consequences of e-cigarettes and vaping products are not yet available. Research involving both types of products is challenging and complex, mostly because of the numerous and rapidly evolving variety of technology and designs, as well as the multiplicity of e-liquid flavors and solvents that are on the market. Notably, the absence of standardized assessments makes research data difficult to interpret and compare. These considerations highlight the urgent need to harmonize research protocols, starting with production guidelines and moving on to vapor generation and physicochemical characterization methods, as well as nonclinical and clinical exposure studies. The specificities of the products constitute challenges to toxicity testing and require the development of ad hoc assessment frameworks, equipment, and methods. In so doing, the objective evaluation and verification of existing evidence must occur and, ultimately, lead to the formulation of standardized methods to test such products.

2-1

E-cigarettes and other vaping devices are engineered to heat a liquid solution so that the aerosol generated (colloquially called “vapor”) can be inhaled by the user. Inhalation of complex mixtures like tobacco smoke and e-cigarette aerosol can cause a wide range of adverse health effects, ranging from simple irritation to systemic diseases. Studies of the liquids, emitted aerosols, and vaping devices are imperative to develop models to define the pathology of potential vaping-related respiratory conditions and the mechanistic pathways at play. The identification, validation, and dissemination of robust in vitro and in vivo methods for the evaluation of emerging tobacco products and their constituents could also advance regulatory decision-making to protect human health. The direct exposure of pulmonary cells to whole e-cigarette aerosol and its individual constituents at the air-liquid interface is the future-oriented approach. In vitro models could also be utilized to study the specific mechanisms of lung injury and dysregulated inflammatory response. Upcoming technologies that might further improve in vitro testing include lung-on-a-chip, which recreates expansion and contraction of the airways during breathing to mimic changes in air and blood flow. Utilizing complex models such as rodent inhalant exposures could yield results quickly. The animal models have several important advantages in furthering our understanding of respiratory effects of e-cigarettes by permitting controlled exposure to an individual ingredient of product liquid that would not be feasible in humans. This presentation will compare the inhalation effects of tobacco smoke and e-cigarettes aerosols. The emphasis will be on understanding how various vaping products differ regarding their inhalation toxicity.

2-2

The development of reduced-risk products aims to provide alternatives to cigarettes that present less risk of harm for adult smokers. Responsible use of flavoring substances in these products may fulfill an important role in product acceptance. While most flavoring substances used in such products are also used by the food industry and are considered safe when ingested, their impact when inhaled requires further assessment. To aid in such an assessment, a three-step approach combining real-time cellular analysis, phenotypic high content screening assays, and gene expression analysis was developed and tested in normal human bronchial epithelial cells with 28 flavoring substances commonly used in e-liquid formulations, dissolved individually or as a mixture in a base solution composed of propylene glycol, vegetable glycerin, and 0.6% nicotine. By employing this approach, we identified individual flavoring substances that potentially contribute greatly to the overall mixture effect (citronellol and alpha-pinene). By assessing modified mixtures, we showed that although cytotoxic effects were found when assessed individually, alpha-pinene did not contribute to the overall mixture cytotoxicity. Most of the cytotoxic effect appeared to be attributable to citronellol, with the remaining substances contributing because of synergistic effects. We developed and used different scoring methods (Tox-Score, Phenotypic Score, and Biological Impact Factor/Network Perturbation Amplitude), ultimately enabling a ranking based on cytotoxicity, phenotypic outcome, and molecular network perturbations. This case study highlights the benefits of testing both individual flavoring substances and mixtures for e-liquid flavor assessment and emphasizes the importance of data sharing for the benefit of consumer safety.

2-3

Questions remain about whether e-cigarette or vaping product use–associated lung injury (EVALI) is a new clinical syndrome or represents an artifact of diagnosis and reporting frequency. The present clinical picture is complicated by newer-generation e-cigarettes that use nicotine salts, which allow more nicotine to be inhaled with less irritation. Nicotine salts may increase the risk of adverse effects to the lungs owing to more frequent and stronger inhalation or may increase the risks of other health effects, such as nicotine poisoning or effects from other potential toxicants such as flavoring agents, lipoid vehicles, or pyrogens. The apparent rise in cases of EVALI also appears to coincide with the increased use of cannabinoid (CBD) oil in these products. The increase in the incidence of ED visits may also be driven by acute intoxication from tetrahydrocannabinol (THC, which has increased in availability and potency), synthetic cannabinoids, and various diluents (e.g., vitamin E acetate and medium-chain triglycerides) that enhance quality and appearance, provide desirable aroma or taste, and lower product cost. Cumulative radiologic, bronchoalveolar lavage, and histopathologic data will be reviewed. Radiographic findings may not be apparent on presentation, but many patients commonly are found to have basilar-predominant consolidation and ground-glass opacity. Histopathological features of acute lung injury have been described, including diffuse alveolar damage, acute fibrinous pneumonitis, and organizing pneumonia.

Session Chairs: Krishna Allamneni, Turning Point Therapeutics, San Diego, CA; and Jeffrey Moehlenkamp, Aclairo® Pharmaceutical Development Group, Inc., Vienna, VA

How does a project have the best chance to survive through internal decision-making to successful launch? A lot of data must be brought forth from discovery or conception to the development phase in a timely manner for a particular project to move forward. Contracts, legal, project management and monitoring, toxicokinetic, toxicology, pathology, immunogenicity or ADA, and bioanalytical experts all have critical/pivotal roles. The intracompany and possibly external PIs as well as potential partners all play their role in moving a project forward, or alternatively, stalling it. So, what are the key functions that need to be lined up for the correct decision-makers and elements to be in place to make the decision of Go or No-Go? This Workshop will explore the planning and timing of key events in drug development. This session is designed for early career toxicologists to be aware of this critical nontoxicology skill needed to lead and/or contribute to a successful nonclinical safety assessment program. Decision-making skills may not have been part of the graduate school’s curriculum, but these are critical to employ along with organizational ability, teamwork, leadership, problem solving, and collaboration in the context of competing regulations, interests and expertise, and prioritization, so toxicologists can lead from any seat no matter the role in the team. The session focuses on keeping the patient and the entire program in the forefront by engaging the executive function in decision-making. A panel discussion with an audience Q&A session will conclude the session.

3-1

During the course of drug development, achieving a goal of a regulatory submission in the timeliest manner possible requires important decisions to be made in all aspects of the program: strategic, tactical, and executional. As a member of the development team, not only does the toxicologist need to plan and execute the nonclinical safety program, but also, they need to consider how an unplanned event may impact the submission timeline, whether that be in the toxicology program, clinical studies, CMC, or others. Decisions may also be needed that consider competing priorities and/or management directives, so toxicologists need to be versatile and able to act with flexibility, sometimes on very short notice. This presentation will focus on key aspects of decision-making in an effort to provide the toxicologist with a foundation upon which to draw in the various situations they may find themselves in as part of a project team. It will cover understanding who the decision-maker is as well as decision-making styles and techniques that could be employed as a team member, individual contributor, consultant, or Study Director to help choose among the alternatives and make an effective decision in a timely manner with the appropriate buy-in.

3-2

Many a great drug may not see the light of the day because of poor planning and coordination of decisional data. This complex process requires coordination of many distinct pathways, all with the common goal of getting the safest, most effective medication to the patients that need it in the most cost-effective manner. Each functional line will face many critical decision points, and it is up to the project manager/coordinator to ensure alignment of these functional areas to drive the development program with speed while not sacrificing quality, safety, and/or efficacy. This talk will be a cross-divisional discussion of decision points from the toxicologist’s perspective and things to consider as a program moves forward. Chemist/Pharmaceutical Scientist: Does the program have an acceptable form of the drug and a formulation? Will adequate supplies of test article be available to conduct the nonclinical program within the applicable regulatory guidances? Pharmacologist: Can a target exposure be predicted based on knowledge of target and modeling? Is there a potential for overt pharmacology? Are knockout animals available to help predict what effects may be observed? Toxicologist/Pathologist: What are the appropriate species for the nonclinical toxicology program? Has a NOAEL been established in the toxicology studies? Is there a minimal data package that would be acceptable? Have appropriate doses been selected for the toxicology studies? Metabolism/Pharmacokinetics: Was an appropriate method developed and validated? Are there special procedures related to blood collection and/or have blood volume requirements been considered? Will the species selected for evaluation cover potential major metabolites in humans? Project Manager/Clinical: Is the nonclinical toxicology plan designed to support the proposed clinical plan in the appropriate region/country? Are there opportunities for acceleration/risk management strategies that could be employed? Will the toxicology studies be reported to support the team’s filing goal? Are the long-term team goals being addressed by the nonclinical toxicology program?

3-3

Securing enough drug to run the studies, formulation and impurity considerations and timing for these analyses, timing of delivery of the drug if the drug cannot be stored, planning for total compound requirements up through clinical development, and species selection with respect to dosing regimens all need to be coordinated. Medical device considerations will be briefly mentioned. For example, issues to settle before testing begins include what type of samples will be needed from the animals; how many animals it will take to collect all the samples (e.g., biodistribution versus histopathology); how many devices will be needed for each test; use of predicate device for supporting information; and engineers needing the device for testing tensile strength but the histopathologist needing to evaluate the tissue interface. What studies can be combined (e.g., implantation and systemic toxicology), what level of detail is needed for a paper-based evaluation of a required biocompatibility testing endpoint, what endpoints cannot be justified on paper, what to do when you fail cytotoxicity, and use of standard graded materials (e.g., Nitinol) will be touched on. Whether a toxicologic consultant or a member of the company team, this person has lot to consider.

3-4

Toxicological study designs often involve multiple quantitative datasets, sometimes generated from different organizations, which necessitates good planning and communication between all parties. Sponsors must consider timelines carefully in the context of the final report and SEND, including which quantitative data points require more time to gather and analyze, which are most critical, and how these should be scheduled appropriately to prevent delays in the drug development process. If a particular component of the study suffers a setback due to a failure, error, or unexpected result, how do the data “catch up” to the rest for inclusion into the final report and SEND package? Case examples will be discussed in the context of planning for events, such as recovering when ISR (incurred sample reanalysis) failures impact the timeline, how pathology peer review can affect the report timeline and SEND data, and what to do when issues are identified during QC of the SEND dataset. The emphasis will be on effective planning, decision-making, communication, and review of these data to ensure an on-time and high-quality study report and SEND dataset for submission.

Session Chairs: David Clarke, Lilly Research Laboratories, Indianapolis, IN; and Helen Prior, National Centre for the Replacement, Refinement & Reduction of Animals in Research (NC3Rs), London, United Kingdom

For biotherapeutics with multiple pharmacologically relevant species, short-term toxicology studies (generally IND-enabling studies supporting Phase I trials) should be performed in a rodent and a nonrodent. ICH S6(R1) outlines options justifying when only one species may be sufficient for subsequent longer-term toxicology studies (e.g., up to six months dosing duration). These options include that “the toxicity profile in the two species is comparable in the short term,” or that “findings are understood from the mechanism of action of the product.” In these cases, the rodent species should be considered to progress to the longer-term studies, unless there is scientific rationale for using nonrodents instead. A key decision for progression to longer-term studies in one or two species revolves around the “similarity” of toxicities between the species identified in the short-term studies. However, definitions of “similar toxicity profile in two species” remain vague; there is lack of clarity on how to apply this in practice and whether the absence of toxicity in two species constitutes a “similar” toxicity profile as outlined in ICH S6(R1). Consequently, Sponsors may continue to use two species to avoid regulatory risk and potential delays in development timelines. Such decisions represent missed opportunities for applying the 3Rs and reducing animal use, particularly of NHPs, during drug development. This session will highlight case studies from industry to share examples of decisions to reduce to one species for longer-term toxicology studies and regulatory perspectives to highlight any common themes or experience that could be applicable for use in future decision-making.

4-1

Over the past three years, the NC3Rs has led a large international working group to review the use of two species within regulatory toxicology packages. Within the database of 172 drug candidates, short-term toxicology studies in two species were conducted for 41 biotherapeutics, comprising 30% of monoclonal antibodies, 87% of recombinant proteins, 100% of synthetic peptides, and 83% of ADCs. Although similar target organ toxicities from the short-term studies were often identified, few molecules that progressed to longer-term studies reduced to a single species. While the reasons for this were not explored within the project, definition and harmonization around the criteria for “similarity” of toxicity profiles may support wider adoption of the flexibility within the ICH S6(R1) Guideline, aligning with opportunities for reducing animal use. Interestingly, there was also one example within the database for a small molecule, working within ICH M3(R2) Guideline, that used two species for two-week duration studies but reduced to a single species for a 13-week duration study to support continued development. This highlights that in certain circumstances, opportunities for reduction to one species for longer-term studies may be appropriate for other drug modalities. Case studies during the session will provide both industry and regulatory perspectives to promote the acceptance of this approach for monoclonal antibodies and other drug modalities for a variety of indications.

4-2

During the course of the drug development process, there are numerous opportunities to implement the 3Rs principles, with the ultimate goal of reducing animal usage, replacing animals with novel in vitro tools, and refining study designs. Given the accepted approach within ICH S6(R1) to potentially reduce to a single preclinical animal species, our organization regularly pressure tests our ability to reduce overall animal use and work toward/within our internal 3Rs practices/considerations and current regulatory guidance allowances. In this context, a number of case examples will be shared illustrating the ways in which we have used the approach of reducing to a single species, allowing a reduction in animals used in toxicity studies across multiple projects and therapy areas. Case examples will cover two general scenarios: (1) monoclonal antibody/recombinant proteins for chronic eye conditions where a single species was progressed to long-term studies (a therapeutic area/platform approach), and (2) a bispecific antibody for chronic metabolic diseases where toxicities were apparent in short-term studies in rodents and nonhuman primates but where the pharmacological activity and anti-drug antibodies in nonhuman primates did allow for longer-term dosing. In the latter example, interactions with regulatory agencies were key in the acceptance of this “single species approach” to enable further clinical development of this particular biologic.

4-3

Of the monoclonal antibodies in Lilly’s past and present development portfolio, over a quarter cross-react with the target in both nonhuman primate (NHP) and rodent species, providing the basis for pharmacological relevancy of each species and their dual use in FHD-enabling toxicology studies. Within this group of monoclonal antibodies, several case studies illustrate opportunities that were considered for reducing to a single species for longer-term (post-FHD-enabling) toxicology studies. In accordance with ICH S6(R1) guidance, consideration for using a single species anchored on the similarity of toxicity profiles between the NHP and rodent species in completed toxicology studies and/or understanding of mechanism of action. Additional factors, such as recapitulation of target signaling pathways, tolerability, species-specific off-target toxicity, exposure, and immunogenicity in each species were also considered on a case-by-case basis. As such, a weight-of-evidence-based approach was taken to determine whether one or two species longer-term toxicology studies were warranted to inform human risk assessment. Presented case studies will include monoclonal antibodies for the treatment of various disease areas, regulated by different review divisions at the US Food and Drug Administration. Regulatory interactions led to either endorsement of using a single species (rodent or NHP) for longer-term toxicology studies or rejection of this proposed approach.

4-4

ICH S6(R1) states that safety evaluation of biotechnology-derived pharmaceuticals (i.e., biologics) should normally include two relevant species when available (i.e., one rodent and one nonrodent species in which the test material is pharmacologically active), at least for short-term (up to one-month duration) toxicology studies. Given the high specificity of biologics, pharmacologic relevance is often limited to one species (typically NHPs), but in some cases, both a rodent and a nonrodent species are pharmacologically relevant. In those cases, there are instances when using only one species may be justified for chronic toxicity testing (e.g., the mechanism of action of the biologic is “well-understood” or the toxicity findings in the short-term toxicity studies are “similar” in both species) as specified in ICH S6(R1). This presentation will provide a regulatory perspective for selecting a single species for chronic toxicity testing of biologics, in the context of ICH S6(R1), when two pharmacologically relevant species (rodent and nonrodent) are available. Case examples will also be presented to highlight important considerations for making these determinations.

4-5

The talk will highlight a number of anonymized case examples covering the following scenarios: (1) where Sponsors have consulted with the MHRA for advice on whether reducing to one species for long-term studies would be appropriate, (2) where the MHRA have recommended to Sponsors that a single species will be sufficient, and (3) where the MHRA have reviewed data from longer-term studies with one species only, both with biological products and “small chemicals.” The talk will also cover what the agency considers to be appropriate within the definition of “similar toxicity profile in two species,” how the agency considers “no findings in either species,” and how Sponsors can liaise with the agency to receive advice or discuss findings.

Session Chairs: William B. Mattes, US Food and Drug Administration, Jefferson, AR; and Peyton Myers, US Food and Drug Administration, Silver Spring, MD

Tox21 focuses on modernizing toxicology for the 21st century. Part of that effort is to evaluate the 3Rs and encourage development and eventual regulatory acceptance of alternative systems that can meet regulatory requirements for public health. Although many in vivo systems are used for regulatory decision-making, alternative models can play a crucial role for toxicologists in both risk assessment as well as efficacy evaluation. In this session, we will discuss multiple in vitro or in silico platforms that are being developed or are in use for risk assessment for the cardiovascular system, hepatic system, and skin sensitization. Next, we will discuss how in vitro assessments may help pave the way for further advancements in efficacy for rare and ultra-rare diseases. Lastly, the impact of inter-individual variability between cells lines based on individual donors will be discussed. The in vitro and in silico platforms in this session will describe both successes and ongoing challenges for both regulators and industry as the community moves toward an ever-increasing in vitro world.

5-1

The CiPA initiative provided a series of in vitro ionic current, in silico, and cellular-based approaches (to which were subsequently added a clinical component) to predict proarrhythmic risk of novel drug candidates for Torsades-de-Pointes. The approaches selected were based on a firm understanding of the mechanisms responsible for this rare arrhythmia, with a focus on defining proarrhythmic risk (based on experience with 28 clinical standards) as compared with reliance on prolongation of the QTc interval on an ECG (a recognized surrogate marker of proarrhythmia). Validation efforts have highlighted various areas requiring additional attention for implementation of this paradigm that focus on biological variability, differences in experimental protocols and analysis, model selection and assessment, and the role of drug exposures. These learnings will be discussed in relation to hazard identification and risk assessment in translating in vitro findings to clinical experiences for more generalized cardiovascular toxicity.

5-2

Drug-induced liver injury (DILI) is a leading cause of attrition, black-box warnings, and post-market withdrawal. Assessing hepatotoxicity risk in drug discovery is challenging, as there is poor concordance of preclinical species in identifying human-relevant hepatotoxicants. As DILI is composed of many different etiologies, companies employ a panel of in vitro models to investigate potential DILI risk, including cytotoxicity assays using primary human hepatocytes and human spheroid liver microtissues, mitochondrial toxicity assays, and transporter inhibition studies, with additional consideration for projected dose/exposure. However, it remains difficult to use human in vitro data to make decisions on compound progression in the absence of preclinical in vivo signals of hepatotoxicity. Accordingly, this presentation will focus on the standard and emerging in vitro tools and the strategies in which they are used to characterize risk for DILI for small molecule programs during lead optimization. In particular, the predictivity of each in vitro assay and parameter associated with DILI individually or in combination with others was evaluated using a 170-compound set composed of approximately 50% clinically relevant hepatotoxicants. This exercise identified and/or confirmed the high predictivity of hepatic spheroids, mitochondrial toxicity, and BSEP inhibition assays to identify compounds associated with DILI retrospectively, which increased significantly considering multiple hazards and clinical plasma exposure. Lastly, case studies describing how this multiparametric approach was leveraged to explore mechanisms of hepatotoxicity for small molecules associated with preclinical and/or clinical hepatotoxicity will also be presented.

5-3

The LLNA is a standard assay to detect sensitization potential of chemicals by dermal exposure in a rodent model. The LLNA has been accepted by multiple regulatory authorities and has been validated by ICCVAM. The classical LLNA has had concerns for many years. Concerns range from the use of animals, to radiolabel use, and to sensitivity. Advances have been made for some aspects (e.g., using alternative markers instead of radiolabels), but essentially, the assay has remained the same for many years. Recently, regulatory agencies have begun the process of investigating and accepting a “defined approach” for replacing the LLNA. This defined approach utilizes in vitro assays, peptide reactivity assays, and physical property evaluations, as well as QSAR read-across predictions, to evaluate potential sensitization. This session will discuss the advances in the defined approach as it relates to the LLNA.

5-4

Surrogate biomarkers in general, and in vitro surrogate biomarkers in particular, have had a tortuous history in regulatory agencies. The US Food and Drug Administration (US FDA) has had several decades of experience with in vitro surrogate biomarkers. Most recently, the US FDA broke new ground with the label expansion for Kalydeco for 23 mutations and 900 patients with the application of an in vitro surrogate biomarker for the measurement of chloride transport in CF patient cells. This example shows the critical scientific, clinical, and regulatory parameters leading to this important precedent in regulatory science.

5-5

The rapid development of novel oncology drugs has revolutionized cancer treatment. However, many of the anticancer agents are associated with severe cardiotoxicity in a subset of patients that cannot be predicted by conventional animal studies. Because the toxicities are often discovered in late-stage clinical trials or even years after drug approval, there is an urgent need to develop translational and sensitive preclinical approaches to assess the risk of cardiotoxicity in humans early in the drug development process and identify patients at higher risk of heart damage well before clinical trials are initiated. Patient-specific induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) are generated from individuals with diverse genetic backgrounds, which may represent the heterogeneity of patient population and be a valuable model to assess inter-individual variability of cardiotoxicity in humans. To explore the potential in using patient-specific iPSC-CMs for cardiotoxicity detection and prediction, herein we evaluated doxorubicin- and tyrosine kinase inhibitor-induced cardiotoxicity with a panel of iPSC-CMs from both healthy and hypertensive donors of the HyperGEN cohort, and different batches of iPSC-CMs derived from a same donor. We found that the inter-individual variabilities were larger than the intra-individual variabilities and patient-specific iPSC-CMs exhibited phenotype- and drug-specific responses. Our results suggest that drug testing with iPSC-CMs from a single individual does not represent the cardiac safety/toxicity risk in a population and using a panel of patient-specific iPSC-CMs allows the evaluation of variable cardiotoxic responses of patients in different populations/ethnic groups and may ultimately guide clinical practice in patient stratification and therapeutic regimen selection.

Session Chairs: Tracey Spriggs, GlaxoSmithKline Consumer Healthcare, Warren, NJ; and R. Daniel Mellon, US FDA, Silver Spring, MD

The world of cannabis-based medicinal and consumer products is rapidly expanding. Products containing cannabidiol (CBD) are virtually everywhere, currently including in foods, dietary supplements, cosmetics, and even clothes. Navigating the legal landscape of CBD-containing products has been challenging, particularly since the passage of the US Agriculture Improvement Act of 2018 (aka, the Farm Bill), which made products derived from hemp (cannabis-based products that contain less than or equal to 0.3% THC on a dry weight basis) no longer controlled substances under the Controlled Substances Act (CSA). Regardless, CBD-containing products are still subject to the same laws and requirements as US Food and Drug Administration (US FDA)–regulated products that contain any other substance. Although US FDA has approved a single cannabidiol drug product (Epidiolex) in 2018, this drug product is indicated for two severe pediatric forms of epilepsy and requires very clear labeling recommendations to delineate the risk:benefit of the drug product for that indication. Despite widespread marketing of CBD-containing products, there are known safety concerns and many unknown questions about the safety and pharmacology of CBD. This session will detail the current legal status of CBD and other important considerations for products derived from cannabis. An overview of the known pharmacology and toxicology of CBD will be provided, and a case example presented. This session will describe the existing concerns regarding widespread use of these products and outline regulatory recommendations for the development of CBD-containing and other cannabis-based drug products for marketing approval.

6-1

The US FDA is working to answer questions about the science, safety, and quality of cannabis-based products and compounds derived from cannabis, particularly CBD. Although the current state versus federal legal landscape of cannabis products is unclear to most of the public, the role of the US FDA in regulation of drugs, including cannabis and cannabis-derived products, includes review of applications to market drugs to determine whether proposed drug products are safe and effective for their intended indications. Cannabis study drugs containing hemp (no more than 0.3% ∆9-tetrahydrocannabinol [THC] on a dry weight basis) and cannabis study drugs controlled under Schedule I of the Controlled Substances Act (CSA) (>0.3% THC on a dry weight basis) remain the jurisdiction of the US FDA Center for Drug Evaluation and Research (CDER). Development of clear guidelines regarding the safety of these products begins with consideration of quality issues that, although largely the same as any other drug product, may be more challenging for cannabis and cannabis-derived study drug products, as these products must comply with the CSA and/or the Farm Bill. This presentation will discuss the current legal landscape for cannabis and cannabis-derived drug products, both containing THC >0.3% (dry weight) as well as those derived from hemp in accordance with the US Agriculture Improvement Act of 2018 (aka the Farm Bill). Regulatory recommendations regarding key quality issues will be discussed, as these have distinct implications for toxicological characterization of any drug product and are critical attributes for any drug development program.

6-2

Manufacturers of unregulated cannabidiol (CBD) products have boasted claims of its use for the treatment of ailments ranging from pain and stress relief to treatment of insomnia. The ease of accessibility to CBD and variability of suggested dosage among manufacturers warrant further investigation into the products themselves. With unregulated production and dosage and a wide variety of claimed indications, is it safe as an umbrella treatment? Based on the lack of scientific data to support claims of efficacy (in the absence of available safety margins) of CBD oil for “over-the-counter” use to treat these ailments, there is a public need for answers. The studies conducted will focus on gathering data through the discipline of safety pharmacology to develop a safety profile using commercially available CBD oil. Safety endpoints will include evaluation of the cardiovascular and central nervous systems using implanted telemetry from nonrestrained subjects. Cardiovascular and electroencephalography (EEG) data will be collected from the nonhuman primate (NHP) following oral administration of CBD oil to assess claims of efficacy, while also evaluating potential safety liabilities. The cardiovascular data will interrogate changes in blood pressure and ECG intervals. The EEG data will be analyzed for potential alterations in sleep architecture. These data will be presented in comparison with stimulant and depressant positive control articles (caffeine and eszopiclone, respectively). In addition, plasma samples will be collected and the bioanalytical data will be used to develop a pharmacokinetic profile of CBD and the two major human metabolites (7-OH-CBD and 7-COOH-CBD). These investigations will be conducted in a controlled laboratory setting and will serve to assess the validity of the manufacturers’ prescribed claims for treatment and to define uncharacterized safety signals following acute administration.

6-3

Greenwich Biosciences has established a world-leading position in the development of plant-derived cannabinoid therapeutics through its proven drug discovery and development processes and regulatory and manufacturing expertise. The company has a deep pipeline of additional clinical-stage cannabinoid product candidates for both orphan and non-orphan indications, with a particular focus on neurological conditions. We have successfully developed an oral formulation of purified cannabidiol, which has been approved by the US Food and Drug Administration (US FDA) and European Medicines Agency (EMA). For a toxicology team, a nonclinical development program for a novel cannabinoid medicine in accordance with the US FDA regulations was an exciting opportunity. The presentation will provide insight into the development journey, describing some of the challenges and how we overcame them. Combining a robust nonclinical data package with clinical safety data, the Greenwich Biosciences team provided a thorough evaluation of the safety profile of CBD-OS to support submission of a successful New Drug Application. In June 2018, the US FDA approved Epidiolex® (cannabidiol) oral solution for the treatment of seizures associated with two rare and severe forms of epilepsy, Lennox-Gastaut syndrome and Dravet syndrome, in patients two years of age and older. This is the first US FDA–approved drug that contains a highly purified drug substance derived from the Cannabis sativa plant. In April 2020, the US Drug Enforcement Agency confirmed that Epidiolex was no longer subject to the Controlled Substances Act (CSA), as a result of the Agricultural Improvement Act of 2018.

6-4

The nonclinical development programs for commercial cannabis-based drug products should be undertaken in accordance with the US FDA botanical guidance. Such a program permits sponsors to leverage human data to support proposed Phase 1 and Phase 2 clinical studies if the existing human data adequately support the safety of the proposed drug product formulation. However, given the rapidly changing market for cannabis-based products with different profiles of cannabinoid compounds, leveraging the “human experience” can be challenging during both early- and late-stage development. The US FDA approval of Epidiolex (cannabidiol or CBD) for two rare and serious pediatric epilepsy disorders brought to light additional data that have a significant impact on our understanding of safety of cannabidiol. The presentation will provide a regulatory perspective on the safety of cannabis-based medicinal products, safety concerns with CBD in widely marketed commercial products, and nonclinical regulatory recommendations for sponsors seeking to develop cannabis-based drug products.

Session Chairs: Natalie S. Holman, Eli Lilly and Company, Indianapolis, IN; and Lauren Mihalcik, Aclairo Pharmaceutical Development Group, Inc., Silver Spring, MD

Oligonucleotide therapeutics such as short interfering RNAs (siRNA) represent a promising class of molecules to reach targets that conventional small and large molecules cannot. With the recent approval of the first siRNA therapies and many more in development, it is critical to understand the specific challenges in profiling the toxicity of these unique drug candidates. In this session, leaders in the siRNA therapeutics field from pharma, biotech, and government will discuss components of IND-enabling toxicity studies, current best practices, ambiguities, and regulatory perspectives related to siRNA therapies. Importantly, exciting advances in siRNA (i.e., targeting extra-hepatic tissues) will also be discussed.

7-1

This presentation will reveal the results of the European Federation of Pharmaceutical Industries and Associations (EFPIA) Oligonucleotide Working Group survey of companies to understand the trends in nonclinical practices and regulatory expectations for oligonucleotide drug safety assessments. Twenty-two companies with varying experience in the siRNA field responded. The survey identified top regulatory challenges and areas of perceived health authority concern. Additional data included choice of species, strategies for toxicology study design, and methods for dealing with impurities and human-specific off-targets. The perceived relevance of existing guidance for oligo development and interest in new oligo-specific guidance were also assessed.

7-2

Oligonucleotide therapies represent a distinct category of drugs under development across multiple divisions in the Center for Drug Evaluation and Research (CDER) at the US Food and Drug Administration (US FDA). They are structurally distinct from typical small molecules, with unique safety considerations. However, in the absence of oligonucleotide-specific guidance documents, currently oligonucleotide products are regulated in large part by small molecule guidance, including ICH M3(R2) and ICH Q3A. siRNA are a class of oligonucleotide therapies with two recent approvals in rare disease indications. We are currently curating a database across all divisions within CDER to explore emerging issues in pharmacology and toxicology and provide both consistency and communication regarding these applications. As this class of oligonucleotide therapy grows, we are dedicated to monitoring unique considerations in development to ensure the safety and efficacy across the spectrum of indications where they could be applied.

7-3

Currently, there are no approved siRNA therapies directed at non-host (e.g., bacterial or viral) targets. However, siRNA technology has significant therapeutic potential for the treatment of infectious diseases, and several investigational siRNA therapies directed against viral targets, including respiratory syncytial virus, hepatitis B virus, human immunodeficiency virus, ebola virus, and SARS-CoV-2, have entered clinical development. Specific challenges for viral targeted siRNA molecules may include species selection, unique PK/PD relationships, and the need for combination toxicology studies. Thus, the nonclinical safety evaluation of these siRNA therapies will require careful consideration and understanding of the target and disease biology, relevant regulatory guidance, and clinical development strategy. This presentation will outline key considerations for the nonclinical safety evaluation for viral-targeted siRNA therapies and review case studies of therapies in this class.

7-4

GIVLAARI® (givosiran) is a ribonucleic acid interference (RNAi) therapeutic that is approved in the US for the treatment of acute hepatic porphyria (AHP) in adult patients. It is a synthetic, double stranded small interfering RNA (siRNA) conjugated to a triantennary N-acetyl galactosamine (GalNAc) ligand to facilitate delivery to the liver. Safety and absorption, distribution, metabolism, and excretion (ADME) properties of GIVLAARI were evaluated in a series of in vitro and in vivo nonclinical studies to support the clinical development. A Good Laboratory Practice (GLP)–compliant safety pharmacology study conducted in monkeys showed no functional cardiovascular or respiratory effects. In the pivotal GLP toxicity studies conducted in rats and monkeys, the no-observed-adverse-effect levels (NOAELs) with once-weekly dosing were 10 and 30 mg/kg, respectively. GIVLAARI was not mutagenic or clastogenic and does not have an immunotoxicity potential. Evaluation of reproduction, embryo-fetal, and postnatal development showed no direct effects associated with exposure to GIVLAARI. GIVLAARI showed similar patterns of the pharmacokinetics (PK) and ADME properties across the nonclinical species tested in vivo and nonclinical species and human in vitro. GIVLAARI was completely absorbed after SC administration, and there was no evidence of accumulation after repeat doses. GIVLAARI has a low likelihood of mediating drug-drug interactions involving CYP isozymes and drug transporters. Overall, GIVLAARI had acceptable nonclinical safety and ADME profiles to support the recommended dose of 2.5 mg/kg once monthly for the treatment of adult patients with AHP.

Session Chairs: Christopher Ellis, US FDA/CDER, Silver Spring, MD; and Tacey White, Aclairo Pharmaceutical Development Group, Inc., Vienna, VA

Evaluating the safety of pharmaceutical products used during lactation is a topic that has garnered substantial interest over the last several years. Although driven primarily by the implementation of the US Food and Drug Administration (US FDA) Pregnancy and Lactation Labeling Rule (PLLR), which provides requirements for the content and format of labeling for human prescription drug and biological products that may be used during lactation, this has also been a topic of recent discussions related to proposed updates to ICH S5(R3). Pharmaceutical labeling communicates important information, allowing for the safe and effective use of approved products in patients, with the PLLR providing specific requirements for the labeling of pharmaceuticals that may be used during lactation (in Section 8.2) in regard to (1) the presence or absence of the drug in milk; (2) the known or predicted effects on the breastfed child from drug exposure through milk; and (3) the effects of the drug on milk production. The extent to which animal data can or cannot inform human risk assessment in these three areas has been a topic for considerable debate. This Workshop will begin by providing an overview of lactational physiology and mechanisms of drug excretion into milk (focusing on similarities and differences between humans and animals used for toxicologic assessment) as well as lactational study designs. The Workshop will also provide perspective and discussion on the usefulness of animal lactation–related data for human risk assessment purposes, as well as considerations for communicating risk in the US prescribing information (USPI).

8-1

Breastfeeding has positive health consequences for both the breastfed infant and the nursing mother. Most nursing mothers are prescribed some medication, which causes some mothers to either discontinue breastfeeding or avoid the medication. One impediment to breastfeeding is the lack of useful information on use during lactation for many drugs, especially newer ones. This relative lack of information is an ongoing problem for mothers and health professionals alike. The principles of drug passage into breastmilk are well established but have not been optimally applied prospectively. Animal lactation models are known to have limitations, so results cannot be directly applied to humans. Although the US FDA has published a draft guidance for clinical lactation studies, data on drug passage into breastmilk are often lacking. When a human study is called for, measurement of drug concentrations in milk is often adequate to estimate safety. Unlike pregnancy, in which large numbers of women need to be studied to assure safety, measurement of drug concentrations in breastmilk in relatively few subjects can provide valuable information to assess drug safety. Although measurement of drug concentrations remains the gold standard, physiologically based pharmacokinetic modeling can potentially be used to screen drugs to estimate their passage into milk and identify those that need clinical lactation studies. Data from lactation studies can be used to develop population pharmacokinetic models with subsequent Monte Carlo simulation to provide an estimate of the spread of exposure values.

8-2

The requirement to demonstrate evidence of maternal transfer of test substances in maternal milk and to determine what, if any, effect these test substances may have on maternal milk production have gained considerable importance in recent years. These studies are often conducted in rodents, generally rats, and maternal animals may be directly exposed to the test article at the time of milk collection (e.g., multi-generation reproductive toxicity or juvenile toxicity studies) or may have been exposed to the test article during early development and are being evaluated for long-term effects as a consequence of such exposures (e.g., pre-/postnatal development studies). This talk will focus on existing nonclinical safety study designs that have been used to assess lactational effects and lacteal transfer of test substances. Specific study design considerations (e.g., maternal age, lactational stage, and duration of separation from pups) will be discussed. Secondary consequences of milk collection on pup growth and development will also be addressed. Other less commonly discussed aspects of lactation and lacteal transfer studies, such as analytical complexity and stability, and matrix effects will also be discussed.

8-3

The US FDA Pregnancy and Lactation Labeling Rule (PLLR) requires the lactation section of the drug label to include information on drug concentration in milk and effects of drug exposure on lactation, if available. These data are used to predict drug exposure to infants through nursing and to assess the safety of this neonatal exposure. Unlike the pregnancy section of the label, which presents information from clinical and animal studies, the PLLR guidance states that due to species differences in lactation physiology between animals and humans, animal data are of limited use in assessing drug exposure and safety in nursing infants. This talk will describe basic similarities and differences in lactation physiology and milk content between animals and humans and whether extrapolation is possible across species. It will also describe other types of animal toxicity and DMPK data that are generated during drug development that could be used to assess safety in nursing infants in addition to extrapolation of drug concentrations in milk.

8-4

The PLLR requires that if only animal lactation data are available, the Risk Summary in Section 8.2 of the USPI must state whether the drug and/or its metabolites are present in animal milk (and the animal species). In addition, it is not uncommon to include statements in this section that recommend women not breastfeed while taking the drug, due to safety concerns related to animal toxicology findings. Much of the nonclinical data used to determine potential drug effects on the developing offspring are obtained from pre-/postnatal development and juvenile toxicology studies, while the value of collecting lactational excretion data and measuring drug concentrations in the milk of lactating animals for human risk assessment purposes is uncertain and will be discussed. Case studies describing the role of animal lactation–related data on clinical risk assessment and communication in the USPI will be presented.

Session Chairs: William B. Mattes, US FDA National Center for Toxicological Research, Jefferson, AR; and Richard D. Beger, US FDA National Center for Toxicological Research, Jefferson, AR

Metabolomics is the comprehensive study of the biochemicals present in cells, tissues, and body fluids, collectively called the “metabolome.” Importantly, its ability to query accessible biofluids (blood, urine, feces, etc.) gives it a unique ability to examine system-wide status and responses in animal, clinical studies, and even in vitro studies. Indeed, an individual’s metabolic state provides a close representation of overall health status and reflects what has been encoded by the genome and modified by diet, environmental factors, and the gut microbiome. This session will highlight several studies showing the power and promise of metabolomics to query normal and pathological states in both nonclinical and clinical settings.

9-1

Metabolomics may be defined as the comprehensive analysis of small molecules in a biosample. This talk will introduce the several approaches and technologies that may be used to conduct such an analysis.

9-2

Acetaminophen (APAP) is a commonly used analgesic drug where overdoses can cause liver injury, liver necrosis, and liver failure. APAP-induced liver injury is associated with the formation of APAP protein adducts, generation of reactive oxygen and nitrogen species, glutathione depletion, and mitochondrial injury. Biomarkers associated with the APAP liver injury include APAP-protein adducts, reactive oxygen species, glutathione, long chain acyl carnitines, and miR-122. The talk will provide a summary of the systems biology discovery process, analytical validation of biomarkers, and translation of biomarkers from the nonclinical to the clinical setting in APAP-induced liver injury.

9-3

The comparative analysis of metabolic networks can provide mechanistic understanding of species-specific differences of metabolism and associated biomarkers and drug targets for various applications. The laboratory rat has been used as a surrogate to study human biology for more than a century. We have generated the first genome-scale reconstruction of Rattus norvegicus metabolism, iRno, and a significantly improved reconstruction of human metabolism, iHsa. Previous work in the lab has used these models to predict biomarkers of toxicity for the liver and the kidney both for in vitro comparative studies of rat and human cells as well as in vitro and in vivo studies in the rat. Here, we present our most recent work in using these reconciled models to build new cardioymcyote-specific models of metabolism to predict biomarkers of cardiotoxicity. These models and their associated methods can serve as powerful computational platforms for contextualizing experimental data and making functional predictions for clinical and basic science applications.

9-4

High-resolution metabolomics refers to use of ultra-high-resolution mass spectrometry and advanced computational methods to obtain ’omics-scale measurements of metabolism. Current capabilities provide relative concentrations of tens of thousands of accurate mass signals broadly including endogenous metabolites; dietary and microbiome products; commercial and environmental chemicals; and an extensive list of drugs, drug metabolites, and health-related supplements and their metabolites. Environmental health research has established a central paradigm for research to connect external exposure to internal dose, internal dose to associated metabolic response, and metabolic response to toxicologic outcomes. Application of this research paradigm to drug use shows that abundance of drug metabolites is correlated with drug dose and that metabolic pathway changes associated with internal dose are evident, some of which appear to be desired metabolic effects while others appear to represent undesired off-target effects. The results establish capabilities for translation to human use to improve optimal therapeutic dosing and minimize adverse side effects.

9-5

p-cresol is a small molecule metabolite that is produced when gut bacteria act upon dietary tyrosine. On earth, gut-produced p-cresol is absorbed into systemic circulation and must be processed in the liver, where the metabolism of p-cresol requires sulfur groups for its metabolism and ultimate removal as a safe excretion product. Many therapeutic drugs, such as acetaminophen, also require sulfur groups for their metabolism. When p-cresol is produced by gut bacteria, it competes for the sulfur pool in the liver, which is ordinarily needed to safely metabolize drugs like acetaminophen. A sulfur deficit can lead to formation of drug intermediates (e.g., N-acetyl-p-benzoquinone imine; NAPQI) that produce hepatic damage. In addition, CYP450 2E1 is an enzyme that governs the formation of NAPQI from acetaminophen. It is important to understand whether changes in the production of p-cresol and expression of CYP450 2E1 in space are sufficient to be of clinical concern. One male twin was on board the International Space Station for one year. Blood p-cresol and CYP450 2E1 transcripts (WBC) were extracted from the longitudinal assessment of the genome, epigenome, transcriptome, proteome, metabolome, and microbiome. A significant elevation in p-cresol (glucuronide, sulfate) was observed in the spaceflight condition. A twofold elevation in gene expression of CYP450 2E1 was observed in space compared with the ground control. The increase in p-cresol and upregulation of CYP450 2E1 in space may pose a previously unidentified risk to the ingestion of specific drugs, which warrants further investigation and, potentially, attention to specific countermeasures.

Session Chairs: Mary Ellen Cosenza, MEC Regulatory & Toxicology Consulting, LLC, Moorpark, CA; and Paul Baldrick, Covance, Harrogate, United Kingdom

The potential for direct or indirect adverse effects on the immune system is an established component of nonclinical testing to support the safe use of new drugs. ICH S8 established testing recommendations, and immune safety–related assessments are routinely conducted for a variety of therapeutic modalities not necessarily in the scope of ICH S8. How these assessments can be used to inform clinical development continues to evolve. This session will review key developments in this arena and will include a review of ICH S8 and other relevant regulatory documents. Regulatory perspectives from the US and EU will be provided by regulatory agency scientists.

10-1

An examination for potential direct or indirect adverse effects on the immune system (immunotoxicity) is an established component of nonclinical testing to support safe use of new drugs. Testing recommendations occur in various regulatory guidance documents, especially ICH S8, and these will be presented. Key evaluation usually occurs in toxicology studies, with further investigative work a consideration if a positive signal is seen. Expectations around whether findings may occur are related to the type of compound being developed, but overall, it can be concluded that our main tool for evaluation of potential immunotoxicity/immunogenicity for a new drug still remains standard toxicology study testing with key assessment for effects on clinical pathology and lymphoid organs/tissues (weights and cellularity). Additional evaluation from studies using a T cell–dependent antibody response (TDAR) and lymphocyte phenotyping is also valuable, if needed.

10-2

This presentation will focus on nonclassical toxicities that are emerging with use of the checkpoint inhibitors and novel cell therapies. There is some literature suggesting delayed immune-related toxicities associated with immunotherapies emerging months to years after termination of treatment. These are certainly not well modeled with current immunotoxicity paradigms.

10-3

This presentation will discuss the translatability of immune safety–related observations for a variety of therapeutic modalities. This presentation will be illustrated by case studies leveraging both nonclinical and clinical data. An update on the HESI work streams on this topic of predictive immune safety–related assays will also be provided.

10-4

The field of immunotoxicity has evolved greatly in recent years and is fraught with new challenges. Much has changed since the release of ICH S8, particularly in the areas of immunostimulation and immunomodulation. This talk will provide insight into the regulatory perspective on multiple recently emerging immune safety issues that are addressed in ICH S8 and the recent CDER/CBER draft guidance. Of note, the recent CDER/CBER draft guidance on the evaluation of the immunotoxic potential of drugs and biologics will be discussed.

10-5

An evaluation of the potential adverse effects of pharmaceuticals on the immune system should be incorporated into standard drug development in accordance with ICH Guidelines. Toxicity to the immune system can encompass a variety of adverse effects, and the evaluation usually occurs in toxicology studies, with further work conducted to evaluate any positive signal that is seen. However, as with all aspects of toxicology, a weight of evidence review should be performed on all available information to determine whether a cause for concern exists. It needs to be remembered that many biotechnology-derived pharmaceuticals intended for humans are immunogenic in animals and the induction of antibody formation in animals is not predictive of a potential for antibody formation in humans. In addition, immunotherapy (or immune therapy) is now becoming a frontline treatment for many tumour types, and it is vital to be able to separate adverse effects from intended pharmacology. This talk will briefly cover standard techniques seen for immunotoxicity testing in Clinical Trial Authorisation (CTA) applications to the UK before concentrating on discussing whether current nonclinical models are fit for purpose with respect to immunotherapy toxicity profiling.

Session Chairs: Patricia Ryan, AstraZeneca, Gaithersburg, MD; and Justine Cunningham, Sana Biotechnology, San Francisco, CA

Genetic therapies, once heralded and later maligned by setbacks, are now astounding the world with clinical proof of their potential to cure patients with devastating diseases. Today, genetic therapies encompass a wide array of delivery (viral and nonviral) and mechanistic approaches, offering novel ways to replace or modify affected genes. The novel mechanisms of genetic therapies have opened pathways to rethink traditional preclinical approaches, bringing opportunities to shed old ideas while embracing the challenges to de-risk these products. The challenges that toxicologists have had to consider involve how to leverage hybrid study designs for combined safety/efficacy studies, evaluate vector persistence, predict for immunogenicity, de-risk for off-target genotoxicities, address risks for germ line transmission, and scale to humans from a single species. As developers look to expand the therapeutic potential of gene therapies, new toxicologists will be challenged with addressing these key questions to demonstrate safety and tolerability. The goal of this Symposium is to learn how successful gene therapy developers have navigated the preclinical space to enable clinical entry and to identify where the new challenges lie ahead.

11-1

Hybrid pharmacology/toxicology studies utilizing animal models of disease are playing an increasingly important role in nonclinical safety assessment of novel gene therapy products. These studies can identify pharmacologically active dose levels and provide insight into the relationship between dose, transgene distribution and expression, and impact on disease biomarkers and potential toxicity. This information can support risk/benefit analysis and selection of potential starting dose levels, as well as dose-escalation schemes in clinical studies. Moreover, regulatory authorities find well-designed hybrid studies acceptable alternatives to toxicity studies in normal animals, which can lead to reduction in animal use. This presentation will discuss advantages and limitations of hybrid pharmacology/toxicology studies and strategies in study design, conduct, and oversight to ensure robust evaluation of efficacy and safety to accelerate gene therapy product development.

11-2

The preclinical development of genetically modified cell therapies via vector-driven gene addition or genetic ablation/addition via editing agents is characterized by case-by-case assessments and determinations of product-specific risks for which granular regulatory guidance is largely not feasible. The unique features of a given product, including the theoretical or actual risks posed by the design, manufacture, and both intended and unintended molecular and cellular modifications of that product, will guide and define the characteristics of an appropriate preclinical package for both first-in-human applications and registration. Both the gene-modifying elements of the product as well as the specifics of the cell type and administration of the cellular product will also influence preclinical development strategy for a specific product. In this presentation, specific aspects of and considerations for the preclinical development of hematopoietic stem cell therapies and T cell therapies will be discussed, including considerations regarding the use of lentiviral vectors for gene addition, as well as editing modalities for gene ablation.

11-3

The first in vivo CRISPR-Cas-based gene-editing experimental medicine (EDIT-101) delivered via sub-retinal injection has recently entered the clinical trial for treating patients with Leber congenital amaurosis 10 (LCA10), an inherited form of blindness caused by mutations in the protein 290 (CEP290) gene. EDIT-101 is an AAV5 vector packaged with DNA encoding the S. aureus Cas9 (SaCas9) protein, along with two guide RNAs. When expressed in photoreceptor cells, the dual gene-editing machinery removes or inverts the IVS26 mutation and restores expression of the full-length CEP290 protein. The presentation will cover the tiered approaches to minimize the off-target editing to optimize the lead guide selection and the preclinical pharmacology and toxicology studies assessing the efficiency, specificity, and tolerability of EDIT-101.

11-4

The first lentiviral-based gene therapy products recently got approval for genetic diseases and cancer. Genetically modified hematopoietic stem cells are approved for the treatment of certain forms of beta-thalassemia and anti-CD19 CAR-T cells are used for the treatment of B-cell precursor acute lymphoblastic leukaemia (ALL) that is refractory or in second or later relapse. Those products are obtained by ex vivo transduction of hematopoietic cells with a self-inactivating lentiviral vector. Dozens of clinical trials are ongoing with lentiviral vectors worldwide, and most of them are based on ex vivo lentiviral transduction. This presentation will review safety data already published on clinical trials and will explore modalities for in vivo applications of lentiviral gene transfer. Regulatory guidance and patient monitoring in gene therapy clinical trials will be discussed.

Session Chairs: Norman Kim, Magenta Therapeutics, Cambridge, MA; and Hanan Ghantous, US FDA, Silver Spring, MD

As a part of the US Food and Drug Administration (US FDA) Center for Drug Evaluation and Research’s (CDER) initiative to modernize the New Drugs Regulatory Program, the Office of New Drugs (OND) was restructured in November 2019. Approved changes in OND created offices that align interrelated disease areas and divisions that provide more focused areas of expertise. Changes increased the number of OND offices that oversee Review Divisions from six to eight and culminated in increasing the number of OND clinical divisions and realigning nonclinical Review Divisions. Six newly restructured pharmacology-toxicology divisions include: Division of Pharm/Tox for Infectious Diseases (DPT-ID); Division of Pharm/Tox for Neuroscience (DPT-N); Division of Pharm/Tox for Cardiology, Hematology, Endocrinology and Nephrology (DPT-CHEN); Division of Pharm/Tox for Immunology and Inflammation (DPT-II); Division of Pharm/Tox of Rare Diseases, Pediatrics, Urologic and Reproductive Medicine (DPT-RPURM); and Division of Hematology/Oncology Toxicology (DHOT). The Symposium will present responsibilities of Associate Directors of Pharm/Tox, as well as an overview, roles and responsibilities, structure/procedures, and indication coverages of each Pharm/Tox Review Division. Potential uncertainties and questions from Sponsors will be outlined and addressed. The Symposium will also include other recent changes, including the Integrated Review process of NDA/BLA and its Summary approval, which incorporates pivotal safety studies in consideration of the risk-benefit for the indication.

12-1

This talk will provide a high-level overview of the Pharm/Tox Divisions within OND.

12-2

This talk will discuss responsibilities of Associate Directors of Pharm/Tox based on the recent restructuring within OND.

12-3

This talk will review each of new Pharm/Tox Divisions (DPT-ID, DHOT, DPT-N, DPT-CHEN, DPT-II, DPT-RPURM) and provide an overview, roles and responsibilities, structure/procedures, and indication coverages of each Pharm/Tox Review Division.

12-4

This talk will present the submission review process and will discuss the 30-day IND Integrated Assessment and the new review process of Integrated NDA/BLA Review within OND.

12-5

A Sponsor’s perspectives of Pharm/Tox restructuring of the Review Divisions and new processes with CDER will be discussed.

Session Chairs: Laura Lotfi, Charles River Laboratories, Senneville QC, Canada; and Julie Douville, Charles River Laboratories, Senneville QC, Canada

Computational and artificial intelligence (AI) tools for predicting toxicity have been envisaged for their considerably high impact on the rate of compound discovery and lead candidate selection in drug research and development. The pharmaceutical and biotech industry as well as Contract Research Organizations (CROs) supporting these programs are in constant search of novel approaches to accelerate transition of drug molecules from laboratory benches to patients. It has been shown that robust tools and sophisticated system algorithms can be exhaustively applied to optimize detection of early safety endpoints to aid in determination of first-in-human dose. One of the various AI approaches that can be used to assist with regulatory communications, impacting clinical decisions and reducing the number of animal models used at these stages, is physiologically based pharmacokinetic (PBPK) modeling. Related publications and regulatory submissions have risen dramatically in recent years. This Symposium will provide attendees with an update on the cutting-edge applications in PBPK and related predicting software and present strategies for implementing PBPK and intelligent modeling in the program design of a drug candidate. It will also highlight considerations and challenges in regulatory submissions and risk assessments. Topics will include an introduction to use of PBPK in drug research, the perspective of regulatory authorities on the validation of such a technology, and successes and challenges in Investigational New Drug (IND) application submissions using this technology, focusing on case-based examples.

13-1

PBPK modeling and simulation treats the distribution and elimination of a molecule on the basis of its interactions with tissues and organs. PBPK models can be parameterized using a combination of in silico, in vitro, and in vivo data, and their use, coupled with mechanistic absorption models (MAM), continues to increase across different industries. Several factors are driving greater adoption, including more education opportunities for scientists; increased confidence in the underlying mathematical algorithms and parameter values; and encouragement from regulatory agencies to incorporate this technology to help reduce R&D costs, animal testing, and regulatory burden. Toxicokinetic parameters are crucial for interpreting biologically relevant exposure. PBPK modeling, when integrated with machine-learning techniques, can provide accurate predictions of physiochemical properties, pharmacokinetic parameters, and systemic plasma levels following oral, inhaled, or dermal administration, using only chemical structure as input. The focus of this presentation will be to discuss recent advancements with PBPK modeling theory and approaches, highlighting various applications from discovery through clinical development. Special focus will be given to “discovery PBPK,” where integrated quantitative structure-activity relationship (QSAR) models are utilized to inform the inputs for PBPK models, allowing researchers to easily screen compound libraries for exposure, assist with animal/human risk assessment, and translate results across species, all to support alternative approaches to animal testing.

13-2

PBPK modeling and simulation approaches are extensively used to address a wide range of clinical questions, such as exploring the effects of extrinsic factors (e.g., concomitant medications, food intake) and intrinsic factors (e.g., age, organ dysfunction, disease status, genetics) on drug exposures. In the past decade, PBPK modeling has been accepted as a regulator tool to predict the potential for drug-drug interactions and to support DDI dosing recommendations. This presentation will discuss how this tool impacts regulatory decision-making and the current status of PBPK applications in regulatory submission and discuss ‘‘best practices’’ in integrating in vitro and in vivo data to develop PBPK models. Examples of PBPK model-informed dosing recommendation will be used to highlight the use of PBPK analysis in various clinical pharmacology applications. The knowledge gaps and research needs in advancing PBPK modeling sciences in drug development and regulatory evaluation will be identified and discussed. Recent updates in US FDA Guidance for Industry on how sponsors should conduct PBPK analyses as well as what to include in a PBPK report will also be discussed to clarify the regulatory expectation.

13-3

Today, in silico studies and trial simulations already complement experimental approaches in pharmaceutical R&D. However, project workflows and current software tools usually focus on isolated aspects of drug action, such as either pharmacokinetics at the organism scale or pharmacodynamic interaction (i.e., systems biology) on the molecular level, even though biology is always multi-scale by nature. This presentation will discuss how the multi-scale physiologically based (PB) modeling concept in our PBPK models and PB-QSP platforms makes it possible to integrate multi-scale data from all biological scales (in vitro, preclinical, individual, and population-level clinical data) and drug, disease, and physiology knowledge across multiple treatments within a therapeutic area. Through modeling and simulation, the multi-scale PB framework is then leveraged in pharma R&D and care for a consistent and quality-controlled buildup and transfer of actionable knowledge and informed decision support across all phases of drug research and development and care.

13-4

PBPK modeling may predict or describe the pharmacokinetics (PK) of drugs in healthy volunteers or specific populations. Readily available software platforms, recent regulatory guidance, and new in silico ADMET tools, as well as an increased awareness in academic institutions, all have promoted interests in expanding PBPK in model-informed drug development. PBPK models have now become a scientifically important tool in drug development to identify drug development risks and to facilitate regulatory interactions or approvals. Verified PBPK models allow a mechanistic understanding of ADME processes, including food or formulations effects on drug absorption, and Drug-Drug Interaction assessment, or can aid in dosing selections and recommendations in specific populations, including pediatrics and patients with organ impairment. Case examples will highlight how PBPK modeling can, for example, (1) impact clinical trial designs, (2) waive studies, (3) inform the dosing regimen in organ impairment populations, (4) inform pediatric trials, and (5) inform product-labeling language. The evolving roles of physiologically based biopharmaceutics (PBBM) will also be covered. This topic is expected to benefit pharmaceutical scientists in both academia or industry interested in learning about PBPK opportunities and limitations.

Session Chairs: Maralee McVean, Loxo Oncology at Lilly, Boulder, CO; and Kathleen A. Funk, Experimental Pathology Laboratories, Inc., Sterling, VA

This Symposium will focus on juvenile bone toxicity—i.e., the design of juvenile animal studies to adequately assess bone toxicity, the usefulness of biomarkers, the imaging modalities to assess bone structure, the interpretation of the significance of bone effects, and relevant regulatory issues. The first speaker will cover study design and interpretation of the data in the context of ICH Guidelines. The second speaker will address in depth how micro-CT applications can be used to evaluate skeletal elements and bone growth in embryo-fetal development (EFD) and pre- and postnatal development (PPND) studies as well as juvenile toxicology studies, while the third speaker will describe the various tools that can be used to monitor bone toxicity, healing, and remodeling, and how they relate to or drive study design. A regulatory perspective on the assessment of juvenile bone toxicity and the potential concerns about adverse skeletal effects in the pediatric population will be presented by the fourth speaker.

14-1

The nonclinical support of a pediatric development plan may include the need for a juvenile toxicity study, the design of which is case by case and determined by the specific questions needing to be addressed. Thus, juvenile toxicity studies are often complex, with a number of subsets of animals and endpoints. Many of these endpoints are not routinely evaluated in general toxicology studies or may be evaluated at various ages depending on the pediatric plan. In addition to standard endpoints of growth, skeletal evaluations may need to be included when there is an identified concern about bone development in the intended pediatric patient population. This talk will include an overview of juvenile toxicity studies, with a focus on evaluations and considerations in designing studies that will sufficiently meet the objectives of including organ-specific endpoints (including bone), interpreting these endpoints, and communicating the results of these endpoints as part of the pediatric risk assessment.

14-2

Assessment of bone in juvenile toxicity studies is an important endpoint in evaluating drug effects on postnatal bone development and growth. The selection of measurements for bone evaluation can be critical for assessing the effect of a drug, and these bone measurements can be specific based on the pharmacological or toxicological target. There are several established imaging modalities that can be used to evaluate bone endpoints, but each modality has its own advantages and disadvantages. In the current talk, an overview of imaging modalities like Radiography, Dual X-ray Absorptiometry, and Micro-CT will be explored, along with appropriate applications, case studies, and recommended considerations for GLP validation of micro-CT imaging systems.

14-3

Identifying bone as a target tissue in drug development to address liability potential is important since several signaling pathways can positively or negatively affect the skeleton. When there are concerns for off-target effects or when pharmacological endpoints are required to assess bone (including bone mass or quality), more comprehensive evaluations are required due to the limitation of standard light microscopic examination of decalcified bones. Species used and study design are important factors in planning a successful study to evaluate bone changes, especially in juvenile studies, as evaluating growing skeleton can be more challenging. Tools are available to assess the potential for a compound to affect bone and growing skeleton, and to characterize those effects on bone turnover, mass, or biomechanical strength. In vivo evaluations of the musculoskeletal system include radiology to identify abnormalities, biochemical markers of bone turnover, and measures of bone mass, density, and geometry, and can extend to ex vivo measurements of bone architecture, bone dynamics by histomorphometry, and bone strength. Bone densitometry techniques (DXA, pQCT, and micro-CT) provide information on bone mineral content, mineral density, and geometry. In addition, a variety of techniques, instrumentation, and pathology endpoints can be used. Principles, requirements, and practices for juvenile toxicology studies will be touched upon as well as the emphasis on study design pitfalls, and the most useful assessments and their impact and interpretation will be highlighted. Integration of these data into juvenile toxicology studies should be routinely performed as part of risk assessment in preclinical drug development if bone growth and development are of potential concern.

14-4

Drugs or biologics can adversely affect the skeleton in multiple ways. The speaker will discuss the interpretation of regulatory approaches to the nonclinical evaluation of drug-related juvenile bone toxicity in juvenile animal studies and the potential findings and implications for clinical development of the drug candidate.

Session Chairs: Kristina Howard, US Food & Drug Administration, Silver Spring, MD; and Florence Burleson, Burleson Research Technologies, Inc., Morrisville, NC

Hypersensitivity reactions are highly complex and comprise a wide range of molecules, proteins, and cells, but it is well established that mast cells and basophils are key contributors during these reactions. These cells are markedly different in how and why they are activated and display remarkable heterogeneity across tissues and species, which impacts our ability to use models to predict their likelihood. Drug hypersensitivity is also known as infusion reaction or drug allergy and remains a critically underinvestigated topic of study. Drug hypersensitivities are often unpredictable and are associated with a high mortality risk because these reactions are often sudden, severe, and not necessarily directly related to dose or pharmacological action of the drug. Unfortunately, preclinical screening for drug allergy/hypersensitivity remains difficult and nonroutine, since reactions may present in specific tissues, only occur in some individuals, or involve tissue-resident cells. This Workshop will discuss challenges in assessing preclinical drug hypersensitivity by providing an introduction into the biology of hypersensitivity followed by speakers addressing in vitro methods, animal models to study in vivo mechanisms, and ex vivo approaches to screen for drug allergies, concluding with a panel discussion addressing current limitations and challenges and future directions.

15-1

Drug hypersensitivity reactions are highly complex, comprising a wide range of molecules, proteins, and cells; thus, assessing and screening for drug reactions remains a substantial challenge. Most drug hypersensitivity reactions are immediate type reactions, such as urticaria, angioedema, and anaphylaxis, or delayed type reactions, which are mainly mediated by CD4+ and CD8+ T lymphocytes. Examples include severe cutaneous adverse reactions such as Stevens-Johnson syndrome, toxic epidermal necrolysis, or drug-induced hypersensitivity syndrome, also called drug rash with eosinophilia and systemic symptoms. This presentation will provide clinical insight into the diagnosis and mechanisms associated with drug allergies and drug hypersensitivity.

15-2

While there has been some progress over the last few years, there are currently no validated or routinely used in vitro models for identifying the potential of low molecular weight drugs to induce hypersensitivity reactions. This talk will focus on the available tools and examples of their application, as well as highlight existing gaps and areas for future research.

15-3

Idiosyncratic drug reactions (IDRs) are adverse reactions that do not occur in most patients. In most cases, this is because they are mediated by the adaptive immune system and require a combination of HLA and T cell receptor that have a high affinity for the drug, or more likely, a drug-modified protein. IDRs are also idiosyncratic in animals; therefore, there are few animal models with characteristics similar to IDRs in humans. We were able to develop an animal model of IDRs with similar characteristics as human IDRs by use of immune checkpoint inhibition. This is analogous to the use of checkpoint inhibitors to treat cancer by promoting an immune response to the cancer. The induction of an adaptive immune response requires an innate immune response, which does not require specific HLA and T cell receptors. It appears that most patients and even animals have a clinically silent innate immune response to drugs that can cause IDRs, and this has the potential to make it possible to screen drugs for their potential to cause IDRs.

15-4

Mast cells are at the center of immediate hypersensitivity reactions, but isolating these cells for study is extremely difficult, as their terminal differentiation occurs in peripheral tissues. Current methods for assessing mast cell activation primarily involve either culturing tumor-derived mast cells or differentiating mast cell precursors; however, neither source completely recapitulates native mast cell responses. This talk will focus on models of human mast cells and their potential to screen for drug hypersensitivity reactions.

Session Chairs: Joseph A. Francisco, Altasciences, Seattle, WA; and Jane J. Sohn, US FDA, Silver Spring, MD

A traditional part of the final afternoon of ACT’s Annual Meeting is Hot Topics. Each year this session includes a variety of topics from leading experts focusing in areas such as: topics of importance to the region in which the annual meeting is held; late breaking regulatory or scientific advances related to toxicology; emerging regional or global health crises; and much more. This year’s meeting, originally planned to be held in Austin, Texas covers the environmental and public health effects of hydraulic fracking, an update on the state of COVID-19 and the US FDA response, and insight into precision medicine.