Developmental Toxicology Studies Research Articles

Evaluation of temperature- and ethanol-related developmental degree variations by a new scoring system (FETAX-score) applicable to Frog Embryo Teratogenicity Assay: Xenopus.

The aim of the present work is to propose a new quantitative assessment method (FETAX-score) for determining the degree of Xenopus laevis embryo development intended for use in embryotoxicity studies. Inspired by a similar scoring system used to evaluate developmental delays (young-for-age phenotypes) in rat embryos cultured in vitro, the FETAX-score was established by considering seven morphological features (head, naris, mouth, lower jaw, tentacles, intestine, anus) that are easily evaluable in tadpoles during the late stages of development at the conclusion of the test. Given that X. laevis development is temperature-dependent and that temperatures below 14°C and above 26°C are teratogenic, the FETAX-score was tested in embryos maintained at 17, 20, 23 and 26°C. No abnormalities were observed in any group, while the total score was temperature-related, suggesting that the FETAX-score is sensitive to moderate distress that does not influence general morphology. Intestine and anus were the least sensitive structures to temperature variations. To assess the applicability of the FETAX-score in developmental toxicological studies, we evaluated FETAX-score in tadpoles exposed during the morphogenetic period to Ethanol (Eth) at concentrations of 0, 0.25, 0.5, 1, 1.5, and 2% v/v. Gross malformations were observed only in tadpoles from the Eth 2% group. By contrast, data analysis of the other Eth groups showed dose-related reductions in the FETAX-score. Tentacles were the most sensitive structures to Eth-related delays. These results support the use of the FETAX-score to quantitatively assess developmental deviations in FETAX embryotoxicity studies.

Standardizing Extracted Data Using Automated Application of Controlled Vocabularies.

Extraction of toxicological end points from primary sources is a central component of systematic reviews and human health risk assessments. To ensure optimal use of these data, consistent language should be used for end point descriptions. However, primary source language describing treatment-related end points can vary greatly, resulting in large labor efforts to manually standardize extractions before data are fit for use. To minimize these labor efforts, we applied an augmented intelligence approach and developed automated tools to support standardization of extracted information via application of preexisting controlled vocabularies. We created and applied a harmonized controlled vocabulary crosswalk, consisting of Unified Medical Language System (UMLS) codes, German Federal Institute for Risk Assessment (BfR) DevTox harmonized terms, and The Organization for Economic Co-operation and Development (OECD) end point vocabularies, to roughly 34,000 extractions from prenatal developmental toxicology studies conducted by the National Toxicology Program (NTP) and 6,400 extractions from European Chemicals Agency (ECHA) prenatal developmental toxicology studies, all recorded based on the original study report language. We automatically applied standardized controlled vocabulary terms to 75% of the NTP extracted end points and 57% of the ECHA extracted end points. Of all the standardized extracted end points, about half (51%) required manual review for potential extraneous matches or inaccuracies. Extracted end points that were not mapped to standardized terms tended to be too general or required human logic to find a good match. We estimate that this augmented intelligence approach saved hours of manual effort and yielded valuable resources including a controlled vocabulary crosswalk, organized related terms lists, code for implementing an automated mapping workflow, and a computationally accessible dataset. Augmenting manual efforts with automation tools increased the efficiency of producing a findable, accessible, interoperable, and reusable (FAIR) dataset of regulatory guideline studies. This open-source approach can be readily applied to other legacy developmental toxicology datasets, and the code design is customizable for other study types. https://doi.org/10.1289/EHP13215.

An optimized radioimmunoassay for quantification of total serum thyroxine (T4) in fetal, neonatal, and pregnant rats

Identifying xenobiotics that interrupt the thyroid axis has significant public health implications, given that thyroid hormones are required for brain development. As such, some developmental and reproductive toxicology (DART) studies now require or recommend serum total thyroxine (T4) measurements in pregnant, lactating, and developing rats. However, serum T4 concentrations are normally low in the fetus and pup which makes quantification difficult. These challenges can be circumvented by technologies like mass spectrometry, but these approaches are expensive and not always widely available. To demonstrate the feasibility of measuring T4 using a commercially available assay, we examine technical replicates of rat serum samples measured both by liquid chromatography mass spectrometry (LC/MS/MS) and radioimmunoassay (RIA). These samples were obtained from rats on gestational day 20 (dams and fetuses) or postnatal day 5 (pups), following maternal exposure to the goitrogen propylthiouracil (0–3 ppm) to incrementally decrease T4. We show that with assay modification, it is possible to measure serum T4 using low sample volumes (25–50 μL) by an RIA, including in the GD20 fetus exposed to propylthiouracil. This proof-of-concept study demonstrates the technical feasibility of measuring serum T4 in DART studies.

Growing Knowledge of Stem Cells as a Novel Experimental Model in Developmental Toxicological Studies

Growing Knowledge of Stem Cells as a Novel Experimental Model in Developmental Toxicological Studies

Analysis of incidence data in developmental toxicity studies: Statistical tests to account for litter effects in fetal defect data.

When analyzing fetal defect incidence in laboratory animal studies, correlation in responses within litters (i.e., litter effects) can lead to increased false-positive rates if litter effects are not incorporated into the analysis. Studies of fetal defects require analysis methods that are robust across a broad range of defect types, including those with zero or near-zero incidence rates in control groups. A simulation study compared power and false-positive rates for six approaches across a range of background defect rates and litter size distributions. Statistical methods evaluated included ignoring the litter effect as well as parametric and nonparametric approaches based on litter proportions, generalized linear mixed models (GLMMs), the Rao-Scott Cochran-Armitage (RSCA) trend test, and a modification to the RSCA (mRSCA) introduced here to improve estimation at low background rates. These methods were also applied to a common and a rare defect from two prenatal developmental toxicology studies conducted by the National Toxicology Program (NTP). At background defect rates of 1%, the mRSCA and parametric litter proportion methods provided gains in power over the nonparametric litter proportion method, the GLMM method, and the RSCA method. Simulations involving litter loss in high-dose groups showed loss of power for both litter proportion methods. The mRSCA test developed here compares favorably with other litter-based approaches and is robust across a range of background defect rates and litter size distributions, making it a practical choice for prenatal developmental toxicology studies involving both common and rare fetal defects.

Reproductive and developmental toxicology studies of iminosugar UV-4

UV-4 (N‐(9‐methoxynonyl)‐1‐deoxynojirimycin) is a host-targeted antiviral agent, which targets mammalian proteins (endoplasmic reticulum glucosidases) rather than virally encoded proteins. This mechanism confers both broad-spectrum activity and low potential for generation of viral drug resistance mutations. Reproductive and developmental studies of UV-4 evaluated effects on fertility and early embryonic development in rats, embryo-fetal development in rats and rabbits, and pre- and postnatal development including maternal function in rats. All reproductive and developmental studies conducted achieved dose levels where parental toxicity (generally decreased body weight, decreased food consumption and adverse clinical signs) were observed. Toxicokinetic evaluations confirmed UV-4 crossed the placenta exposing fetal rats and rabbits in utero. Adverse findings in reproductive and developmental studies included decreases in sperm motility with histopathology correlates, visceral and skeletal malformations, changes in eye opening, air drop reflex, vaginal opening and preputial separation. The combined results of the fertility and early embryonic developmental study and pre- and postnatal study suggested that there may be an increased risk for male fertility. These effects are similar to those reported in pre-clinical studies of the structurally related drug Miglustat (N-butyl-1-deoxynojirimycin), therefore UV-4 may have risk of developmental or reproductive adverse outcomes in humans similar to existing approved agents in this drug class.

Non-clinical considerations for supporting accelerated inclusion of pregnant women in pre-licensure clinical trials with anti-HIV agents.

IntroductionTo allow the continued participation of women enrolled in pre‐licensure clinical trials who become pregnant, and to potentially enrol pregnant women in clinical trials, non‐clinical developmental and reproductive toxicology studies (DART) are essential. Generally during pharmaceutical development, DART studies are conducted late during clinical development, leading to the exclusion of pregnant women from enrolment and withdrawal of women becoming pregnant during pre‐licensure trials.DiscussionCompleting all DART studies prior to or early during the conduct of phase 3 trials (i.e. earlier than current common practice) can accelerate and facilitate the inclusion of women who become pregnant during pre‐licensure trials to remain on study drug and to potentially enrol pregnant women more rapidly. Promoting complementary strategies, such as alternative combinations of DART study designs and physiologically based pharmacokinetic modelling, could better inform drug dosing and safety in pregnancy at an earlier stage in drug development. The interpretation of the results of non‐clinical DART studies is often complex. Institutional review boards/ethics committees should have access to relevant expertise for interpretation and application of results of non‐clinical developmental and reproductive toxicity studies. Clear communication and thorough understanding of non‐clinical findings and the overall benefit–risk profile of the product are critical to review protocols and determine if women who become pregnant during a clinical trial could continue on study drug and/or to enrol pregnant women in the trial. The informed consent document should be well written so that participants can make an informed decision to stay on study drug or participate in a trial during pregnancy. Ultimately, the decision to allow women who become pregnant during pre‐licensure trials to remain on study will depend on the totality of the evidence and benefit–risk considerations.ConclusionsWe propose that industry completes non‐clinical reproductive toxicity studies prior to or early during the conduct of phase 3 trials in HIV drug development, especially for priority agents, and potentially uses alternative DART study design strategies to achieve this goal.

Placental model as an important tool to study maternal-fetal interface

The placenta is a temporary organ that plays critical roles at the maternal-fetal interface. Normal development and function of the placenta is dependent on hormonal signaling pathways that make the placenta a target of endocrine disrupting chemical (EDC) action. Studies showing association between prenatal exposure, hormone disruption, and reproductive damage indicate that EDCs are developmentally toxic and can impact future generations. In this context, new placental models (trophoblast-derived cell lines, organotypic or 3D cell models, and physiologically based kinetic models) have been developed in order to create new approach methodology (NAM) to assess and even prevent such disastrous toxic harm in future generations. With the widespread discouragement of conducting animal studies, it has become irrefutable to develop in vitro models that can serve as a substitute for in vivo models. The goal of this review is to discuss the newest in vitro models to understand the maternal-fetal interface and predict placental development, physiology, and dysfunction generated by failures in molecular hormone control mechanisms, which, consequently, may change epigenetic programming to increase susceptibility to metabolic and other disorders in the offspring. We summarize the latest placental models for developmental toxicology studies, focusing mainly on three-dimensional (3D) culture models.

COVID-19 Vaccine in Pregnant and Lactating Women: A Review of Existing Evidence and Practice Guidelines.

Coronavirus 2019 (COVID-19) has created a global pandemic that is devastating human lives, public healthcare systems, and global economies. Multiple effective and safe COVID-19 vaccines have been developed at an unprecedented speed due to the efforts of the scientific community, and collaboration between the federal government and pharmaceutical companies. However, the continued exclusion of pregnant and lactating women from the COVID anti-viral and vaccine trials has created the paradox of a lack of empirical evidence in a high-risk population. Based on the experience of similar prior vaccines, animal developmental and reproductive toxicology studies, and preliminary findings from human studies, various healthcare professional advisory committees (Advisory Committee on Immunization Practices, American College of Obstetricians and Gynecologists, Society for Maternal-Fetal Medicine, and Academy of Breastfeeding Medicine) have issued guidance supporting COVID-19 vaccination in pregnant and lactating women. In this article, we summarize the available data on the efficacy and safety profile of COVID-19 vaccination in pregnant and lactating women, review the challenges of vaccine hesitancy, and include recommendations for healthcare providers.

Coronavirus Disease 2019 (COVID-19) Vaccines and Pregnancy: What Obstetricians Need to Know.

Coronavirus disease 2019 (COVID-19) vaccines have begun to be distributed across the United States and to be offered initially to priority groups including health care personnel and persons living in long-term care facilities. Guidance regarding whether pregnant persons should receive a COVID-19 vaccine is needed. Because pregnant persons were excluded from the initial phase 3 clinical trials of COVID-19 vaccines, limited data are available on their efficacy and safety during pregnancy. After developmental and reproductive toxicology studies are completed, some companies are expected to conduct clinical trials in pregnant persons. Until then, pregnant persons and their obstetricians will need to use available data to weigh the benefits and risks of COVID-19 vaccines. Issues to be considered when counseling pregnant persons include data from animal studies and inadvertently exposed pregnancies during vaccine clinical trials when available, potential risks to pregnancy of vaccine reactogenicity, timing of vaccination during pregnancy, evidence for safety of other vaccines during pregnancy, risk of COVID-19 complications due to pregnancy and the pregnant person's underlying conditions, and risk of exposure to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and potential for risk mitigation. The Centers for Disease Control and Prevention, the American College of Obstetricians and Gynecologists, and the Society for Maternal-Fetal Medicine have each issued guidance supportive of offering COVID-19 vaccine to pregnant persons. As additional information from clinical trials and from data collected on vaccinated pregnant persons becomes available, it will be critical for obstetricians to keep up to date with this information.

The need for a global COVID-19 maternal immunisation research plan

The need for a global COVID-19 maternal immunisation research plan

Re-evaluation of name of hydrogenated poly-1-decene (E 907) as food additive.

The Panel on Food Additives and Flavourings added to food (FAF) provided a scientific opinion re‐evaluating the safety of hydrogenated poly‐1‐decene (E 907) when used as a food additive. Hydrogenated poly‐1‐decene (E 907) is authorised as a food additive in the EU in accordance with Annex II to Regulation (EC) No 1333/2008. Hydrogenated poly‐1‐decene is of low acute toxicity and does not raise concern for genotoxicity. Toxicity and carcinogenicity, as well as reproductive and developmental toxicological studies, were not available; therefore, the Panel based the derivation of the acceptable daily intake (ADI) on the no observed adverse effect level (NOAEL) identified in the subchronic study in rats and established an ADI of 20 mg/kg bw per day. Dietary exposure to hydrogenated poly‐1‐decene (E 907) from its use as a food additive was calculated based on regulatory maximum level exposure assessment scenario. Mean exposure to hydrogenated poly‐1‐decene (E 907) from its use as a food additive ranged from no exposure in infants to 2.35 mg/kg bw per day in toddlers. The high exposure to hydrogenated poly‐1‐decene (E 907) ranged from 0 mg/kg bw per day in infants and adults to 6.69 mg/kg bw per day in toddlers. The exposure estimates in the regulatory maximum level exposure assessment scenario did not exceed the ADI of 20 mg/kg bw per day for all population groups. The Panel concluded that the exposure to hydrogenated poly‐1‐decene (E 907) does not raise a safety concern when used at the maximum permitted levels.

Zebrafish yolk sac microinjection of thalidomide for assessment of developmental toxicology.

Zebrafish offer advantages over traditional rodent models in developmental toxicology studies, including low maintenance costs, high fecundity, genetic diversity, and reduced animal welfare concerns (1,2).

Induced Pluripotent Stem Cells (iPSCs) in Developmental Toxicology.

The discovery of induced pluripotent stem cells (iPSCs) by Dr. Shinya Yamanaka and his team has opened up many avenues of research. This includes medical initiatives such as the Precision Medicine and Personalized Medicine initiatives to use patient-specific stem cells to guide medical professionals on the base courses of treatment for various disorders based on the patient's own genetic background, i.e., targeting the best treatment for the individual patient. However iPSC technology has greater potential than disease modeling and regenerative medicine therapies. In this chapter, we will outline how to culture and maintain human iPSCs, differentiate human iPSCs into neurons, and discuss how iPSCs can be utilized for developmental toxicology studies. Furthermore, this chapter will highlight a burgeoning field using iPSCs to examine personalized exposure risks.

A Three-Dimensional Organoid Culture Model to Assess the Influence of Chemicals on Morphogenetic Fusion.

Embryologic development involves cell differentiation and organization events that are unique to each tissue and organ and are susceptible to developmental toxicants. Animal models are the gold standard for identifying putative teratogens, but the limited throughput of developmental toxicological studies in animals coupled with the limited concordance between animal and human teratogenicity motivates a different approach. In vitro organoid models can mimic the three-dimensional (3D) morphogenesis of developing tissues and can thus be useful tools for studying developmental toxicology. Common themes during development like the involvement of epithelial-mesenchymal transition and tissue fusion present an opportunity to develop in vitro organoid models that capture key morphogenesis events that occur in the embryo. We previously described organoids composed of human stem and progenitor cells that recapitulated the cellular features of palate fusion, and here we further characterized the model by examining pharmacological inhibitors targeting known palatogenesis and epithelial morphogenesis pathways as well as 12 cleft palate teratogens identified from rodent models. Organoid survival was dependent on signaling through EGF, IGF, HGF, and FGF pathways, and organoid fusion was disrupted by inhibition of BMP signaling. We observed concordance between the effects of EGF, FGF, and BMP inhibitors on organoid fusion and epithelial cell migration in vitro, suggesting that organoid fusion is dependent on epithelial morphogenesis. Three of the 12 putative cleft palate teratogens studied here (theophylline, triamcinolone, and valproic acid) significantly disrupted in vitro organoid fusion, while tributyltin chloride and all-trans retinoic acid were cytotoxic to fusing organoids. The study herein demonstrates the utility of the in vitro fusion assay for identifying chemicals that disrupt human organoid morphogenesis in a scalable format amenable to toxicology screening.

Polymer Size Affects Biodistribution and Placental Accumulation of the Drug Delivery Biopolymer Elastin‐Like Polypeptide in a Rodent Pregnancy Model

Pregnancy has been a limiting factor in drug development, and pregnant females are often excluded from clinical trials. Developmental and reproductive toxicology studies are often done in mice, rats and rabbits during the drug development process for a novel therapeutic, however very little drug development occurs for disorders specific to pregnancy due to the risk of deleterious effects on the developing fetus. Nevertheless, there is still a need for drug administration during pregnancy and for development of treatments for pregnancy – specific conditions. We have approached this problem by developing a novel drug delivery system that prevents placental drug transfer. In the emerging field of biologics, the effects during pregnancy are variable. While some protein therapeutics are too large to cross the placental barrier, many biologics are monoclonal antibodies or Fc domain fusion proteins that are substrates for the placental antibody transport machinery, and these agents can be actively shuttled into the fetal circulation. Our lab has developed a drug delivery system based on a biopolymer called elastin‐like polypeptide (ELP) that does not cross the placental barrier. ELPs consist of a repetitive five amino acid motif. ELPs can be easily modified to attach therapeutic proteins or peptides, and small drugs can be chemically attached to them. Previous studies have showed that little to no ELP crosses the placental barrier, and ELPs can be safely used as carriers to prevent placental drug transfer. However, all previous work in pregnancy models has been done with a single ELP molecule of 60 kDa. Recently, we have studied the effect of molecular weight (MW) on the pharmacokinetics, biodistribution and renal deposition of ELPs in mice. However, given that pharmacokinetics could change during pregnancy and that placental transfer may be size dependent, the goal of this study was to measure the effects of polymer size on pharmacokinetics, biodistribution, and placental transfer of ELP in a rodent pregnancy model. Three ELP proteins, 25, 50 and 86 kDa, were fluorescently labeled and administered via bolus intravenous injection to timed pregnant Sprague Dawley rats on gestational day 14. Plasma clearance was determined to define the plasma pharmacokinetics. The biodistribution of each ELP construct was determined by whole‐organ ex vivo fluorescence imaging. Placental distribution was determined in feto‐amnio‐placental units by quantitative fluorescence and histological analysis. Increasing MW resulted in an increase in organ ELP levels, except in the kidneys where an opposite effect was observed. Kidney levels were 6.7, 5, and 1.7 μM for 25, 50 and 86 kDa ELP following an intravenous dose of 1.5 μmol/kg. Placental levels increased with an increase in MW from 0.05, 0.26 to 0.5 μM for 25, 50 and 86 kDa ELP, while in the pups, little to no ELP was detected. Plasma clearance rate was inversely related to MW, and terminal half‐life increased with an increase in MW. Pharmacokinetics and biodistribution of ELPs are size dependent, but they do not affect placental transfer.Support or Funding InformationSupported by NIH NHLBI Grant R01HL121527 (GLB).This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Categorization of fetal external findings in developmental toxicology studies by the Terminology Committee of the Japanese Teratology Society.

Categorization of fetal external findings in common laboratory animals, intended to make the agreement at Berlin Workshop in 2014 more practical, was proposed by the Terminology Committee of the Japanese Teratology Society at the Workshop in the 55th Japanese Teratology Society Annual Meeting in 2015. In the Workshop, 73 external findings, which had been categorized as "Gray zone" anomalies but not as "Malformation" or "Variation" in the 2014 Berlin Workshop, were discussed and classified as Malformation, "Non-structural abnormality," Variation, and "Not applicable." The proposal was based on the results of a survey conducted in 2014, where 20 facilities (including pharmaceutical, chemical, and pesticide companies and contract laboratories) and 2 selected expert teratologists in Japan were asked for their opinions on the categorization of these findings. Based on the discussion, Japanese Teratology Society members have agreed that 42 out of the 73 findings can be classified as Malformations (38), Non-structural abnormalities (3), Malformations/Non-structural abnormalities (1), and Variations (0), while the remaining 31 findings were recommended to be categorized as Not applicable for fetuses. The details of the classification are shown on the website of the Japanese Teratology Society (http://www.umin.ac.jp/cadb/External.pdf).

Re-evaluation of silicon dioxide (E551) as a food additive.

The EFSA Panel on Food Additives and Nutrient Sources added to Food (ANS) provides a scientific opinion re‐evaluating the safety of silicon dioxide (E 551) when used as a food additive. The forms of synthetic amorphous silica (SAS) used as E 551 include fumed silica and hydrated silica (precipitated silica, silica gel and hydrous silica). The Scientific Committee on Food (SCF) established a group acceptable daily intake (ADI) ‘not specified’ for silicon dioxide and silicates. SAS materials used in the available biological and toxicological studies were different in their physicochemical properties; their characteristics were not always described in sufficient detail. Silicon dioxide appears to be poorly absorbed. However, silicon‐containing material (in some cases presumed to be silicon dioxide) was found in some tissues. Despite the limitations in the subchronic, reproductive and developmental toxicological studies, including studies with nano silicon dioxide, there was no indication of adverse effects. E 551 does not raise a concern with respect to genotoxicity. In the absence of a long‐term study with nano silicon dioxide, the Panel could not extrapolate the results from the available chronic study with a material, which does not cover the full‐size range of the nanoparticles that could be present in the food additive E 551, to a material complying with the current specifications for E 551. These specifications do not exclude the presence of nanoparticles. The highest exposure estimates were at least one order of magnitude lower than the no observed adverse effect levels (NOAELs) identified (the highest doses tested). The Panel concluded that the EU specifications are insufficient to adequately characterise the food additive E 551. Clear characterisation of particle size distribution is required. Based on the available database, there was no indication for toxicity of E 551 at the reported uses and use levels. Because of the limitations in the available database, the Panel was unable to confirm the current ADI ‘not specified’. The Panel recommended some modifications of the EU specifications for E 551.

Optical Projection Tomography with a Tissue Clearing Agent for Developmental and Reproductive Toxicology Studies.

Developmental and reproductive toxicology (DART) testing represents an expensive and time-consuming stage in determining the toxicological profile of new chemical entities. Within DART studies, morphological evaluation of fetal skeletons for developmental abnormalities typically requires 7 to 14 days. Current processing techniques involve digestion of soft tissue using a strong base (KOH), followed by qualitative assessment of the remaining skeletal tissue by a fetal morphologist. Micro-computed tomography (micro-CT) has been proposed as a nondestructive image-based alternative for quantitative assessment of skeletal morphology. Such methods eliminate the need for extensive tissue processing and can be paired with quantitative analysis algorithms. However, due to the significant capital and operational expenses required for micro-CT imaging, this approach has yet to gain widespread traction and regulatory acceptance. A novel tissue clearing agent was used in 1-week-old rats to render soft tissue optically transparent. Alizarin red was used to stain the skeleton. High dynamic range optical trans-illumination images were then acquired with an optical-CT imaging system and rendered as three-dimensional images of skeletal structure. High dynamic range-based optical-CT imaging of chemically cleared tissues can rapidly generate high resolution (50-250 μm) reconstructions of whole skeletons. In summary, this study demonstrates that the combination of tissue clearing, optical imaging, and novel reconstruction algorithms may present a new paradigm for high-throughput evaluation of tissues in DART testing. Birth Defects Research 110:12-16, 2018. © 2017 Wiley Periodicals, Inc.

Reproductive and developmental toxicology studies with gantenerumab in PS2APP transgenic mice

Gantenerumab is intended for the treatment of Alzheimer’s disease. It is a fully human recombinant monoclonal IgG1 which binds aggregated forms of amyloid beta such as Aβ oligomers, fibrils and neuritic amyloid plaques. A full package of developmental and reproductive toxicity (DART) studies was performed in the PS2APP double-transgenic mouse model of Alzheimer’s disease. A combined fertility and embryo fetal development study and a pre-and post-natal development study were performed. The PS2APP mouse model allowed a more complete DART evaluation than would have been possible in conventional species or strains which do not express the target antigen of gantenerumab. No developmental or reproductive hazards were identified.