Developmental Toxicity Studies Research Articles

Concordance between alizarin red stained skeleton and micro-CT skeleton evaluation methods: A case study in New Zealand White rabbits.

The objective of this study was to examine the fetal skeletons using both alizarin red stain and micro-computed tomography (CT) images; investigate differences, and to determine if the conclusions of the study were the same regardless of the examination method. A candidate drug was given orally by gavage to pregnant New Zealand White rabbits on gestation day (GD) 7 to GD 19 (mating = GD 0) at doses of 0 (control), 0.02, 0.5, 5, and 15 mg/kg/day. Maternal toxicity was evident at ≥0.02 mg/kg/day. The 199 fetal skeletons (totaling 50,546 skeletal elements) obtained at cesarean delivery on GD29 were first stained with Alizarin Red S, then imaged by a Siemens Inveon micro-CT scanner. All fetal skeletons were examined by both methods, without knowledge of dose group, and the results were compared. In total, 33 types of skeletal abnormalities were identified. There was 99.8% concordance of results comparing stain to micro-CT. Ossification of the middle phalanx of the forepaw digit 5 showed the greatest difference between the two methods. Overall, micro-CT imaging is a realistic, and robustalternative to skeletal staining to examine fetal rabbit skeletons in developmental toxicity studies.

Developmental Toxicity Studies: The Path towards Humanized 3D Stem Cell-Based Models

Today, it is recognized that medicines will eventually be needed during pregnancy to help prevent to, ameliorate or treat an illness, either due to gestation-related medical conditions or pre-existing diseases. Adding to that, the rate of drug prescription to pregnant women has increased over the past few years, in accordance with the increasing trend to postpone childbirth to a later age. However, in spite of these trends, information regarding teratogenic risk in humans is often missing for most of the purchased drugs. So far, animal models have been the gold standard to obtain teratogenic data, but inter-species differences have limited the suitability of those models to predict human-specific outcomes, contributing to misidentified human teratogenicity. Therefore, the development of physiologically relevant in vitro humanized models can be the key to surpassing this limitation. In this context, this review describes the pathway towards the introduction of human pluripotent stem cell-derived models in developmental toxicity studies. Moreover, as an illustration of their relevance, a particular emphasis will be placed on those models that recapitulate two very important early developmental stages, namely gastrulation and cardiac specification.

Mammalian toxicity of trifluoroacetate and assessment of human health risks due to environmental exposures.

While trifluoroacetic acid has limited technical uses, the highly water-soluble trifluoroacetate (TFA) is reported to be present in water bodies at low concentrations. Most of the TFA in the environment is discussed to arise from natural processes, but also with the contribution from decomposition of environmental chemicals. The presence of TFA may result in human exposures. For hazard and risk assessment, the mammalian toxicity of TFA and human exposures are reviewed to assess the margin of exposures (MoE). The potential of TFA to induce acute toxicity is very low and oral repeated dose studies in rats have identified the liver as the target organ with mild liver hypertrophy as the lead effect. Biomarker analyses indicate that TFA is a weak peroxisome proliferator in rats. TFA administered to rats did not induce adverse effects in an extended one-generation study and in a developmental toxicity study or induce genotoxic responses. Based on recent levels of TFA in water and diet, MoEs for human exposures to TFA are well above 100 and do not indicate health risks.

Developmental and reproduction toxicity studies of Biolimus A9 in SD rats

Biolimus A9 (BA9) is a novel rapamycin derivative. In this report we evaluated the potential toxicity of BA9 in a developmental and reproduction toxicity study (segment Ⅰ, Ⅱ, Ⅲ). In segment I, body weight gains in F0 rats receiving 0.80 mg/kg/day were decreased. A lower fertility index of males was observed and females failed to become pregnant in the 0.80 mg/kg/day group. The number of live fetuses and implantations were decreased while the number of dead fetuses, resorptions, and implantation losses were increased in the 0.12 mg/kg/day group. In segment Ⅱ, maternal toxicity: body weight gains in F0 females receiving 0.036 and 0.090 mg/kg/day group were decreased. Embryo toxicity: In the 0.090 mg/kg/day group, weights and body lengths of fetuses were decreased, the numbers of viable fetuses was decreased and resorbed fetuses increased. Teratogenic effects: The percent of visceral variations and skeletal variations were both increased in the 0.090 mg/kg/day group. In segment Ⅲ, dosing F0 rats with BA9 at dose levels of 0.12 and 0.80 mg/kg/day resulted in reproductive and maternal toxicity, consisting of prolonged labor, dystocia, increased mortality, along with reductions in lactation food consumption. F1 rats in the 0.12 mg/kg/day group showed reproductive and developmental toxicity consisting of body weight decreases, decreased food consumption after weaning and a reduction in the gestation index of pregnant rats. Based on these findings, the no-observed-adverse-effect-level (NOAEL) of BA9 toxicity in segment Ⅰ and Ⅲ was 0.02 mg/kg/day. The NOAEL in segment Ⅱ was 0.015 mg/kg/day.

Dimesulfazet (Pesticides).

Food Safety Commission of Japan (FSCJ) conducted a risk assessment of a sulfonanilide herbicide, dimesulfazet (CAS No. 1215111-77-5), based on results from various studies. The data used in the assessment include the fate in plants (paddy rice), residues in crops, fate in animals (rats), subacute toxicity (rats, mice and dogs), chronic toxicity (dogs), combined chronic toxicity/carcinogenicity (rats), carcinogenicity (mice), acute neurotoxicity (rats), subacute neurotoxicity (rats), two-generation reproductive toxicity (rats), developmental toxicity (rats and rabbits), and genotoxicity. The major adverse effects of dimesulfazet from those test results were observed in body weight (suppressed body weight gain in all test results), kidneys (increased weight in rats) and urinary bladder (urothelial hyperplasia in mice and dogs). None of carcinogenicity, neurotoxicity and genotoxicity were observed. No obvious effects on fertility were detected. The lowest no-observed-adverse-effect level (NOAEL) obtained from all the studies was 0.39 mg/kg bw per day in two-year combined chronic toxicity/carcinogenicity study in rats. On the basis of this value, FSCJ specified an acceptable daily intake (ADI) of 0.0039 mg/kg bw per day after applying a safety factor of 100 to the NOAEL. The lowest NOAEL for potential adverse effects after a single oral administration of dimesulfazet was 15 mg/kg bw per day in the developmental toxicity study in rabbits. FSCJ thus specified an acute reference dose (ARfD) of 0.15 mg/kg bw after applying a safety factor of 100 for women who are pregnant or might be pregnant. For the general population, an ARfD of 0.41 mg/kg bw after applying a safety factor of 300 (additional factor 3 by applying LOAEL of 125 mg/kg bw resulted from acute neurotoxicity study in rats).

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.

Points to Consider in the Development and Information Provision of Vaccines for Vaccination during Pregnancy: A Survey.

This report surveyed vaccination decisions during pregnancy based on the package inserts of vaccines approved in Japan, the USA, and Europe. Furthermore, it evaluates vaccination decision-making factors based on the characteristics of the target infections and the modality of the vaccines. Live vaccines known to cause fetal abnormalities are contraindicated for pregnant women, whereas vaccines for life-threatening infectious diseases are authorized for administration during pregnancy when the need is recognized, even for live vaccines. We compared the World Health Organization and European Medicines Agency guidelines on the development of vaccines for pregnant women and surveyed the details of the studies to collect information on SARS-CoV-2 vaccination during pregnancy. In compliance with the guidelines, for all SARS-CoV-2 vaccines, non-clinical reproductive and developmental toxicity studies and clinical trials including non-pregnant women of childbearing age were conducted prior to the vaccination of pregnant women. For all vaccines, information from registries on vaccination during pregnancy are used for post-marketing surveillance. While it is desirable to vaccinate women before pregnancy through planned immunization, whenever possible, pandemics such as H1N1 influenza and COVID-19 may require vaccination even during pregnancy. Necessary and sufficient studies for the decision of vaccination during pregnancy should be carried out promptly.

Computational model for fetal skeletal defects potentially linked to disruption of retinoic acid signaling.

All-trans retinoic acid (ATRA) gradients determine skeletal patterning morphogenesis and can be disrupted by diverse genetic or environmental factors during pregnancy, leading to fetal skeleton defects. Adverse Outcome Pathway (AOP) frameworks for ATRA metabolism, signaling, and homeostasis allow for the development of new approach methods (NAMs) for predictive toxicology with less reliance on animal testing. Here, a data-driven model was constructed to identify chemicals associated with both ATRA pathway bioactivity and prenatal skeletal defects. The phenotype data was culled from ToxRefDB prenatal developmental toxicity studies and produced a list of 363 ToxRefDB chemicals with altered skeletal observations. Defects were classified regionally as cranial, post-cranial axial, appendicular, and other (unspecified) features based on ToxRefDB descriptors. To build a multivariate statistical model, high-throughput screening bioactivity data from >8,070 chemicals in ToxCast/Tox21 across 10 in vitro assays relevant to the retinoid signaling system were evaluated and compared to literature-based candidate reference chemicals in the dataset. There were 48 chemicals identified for effects on both in vivo skeletal defects and in vitro ATRA pathway targets for computational modeling. The list included 28 chemicals with prior evidence of skeletal defects linked to retinoid toxicity and 20 chemicals without prior evidence. The combination of thoracic cage defects and DR5 (direct repeats of 5 nucleotides for RAR/RXR transactivation) disruption was the most frequently occurring phenotypic and target disturbance, respectively. This data model provides valuable AOP elucidation and validates current mechanistic understanding. These findings also shed light on potential avenues for new mechanistic discoveries related to ATRA pathway disruption and associated skeletal dysmorphogenesis due to environmental exposures.

P21-01 Challenges and practical examples in creation of SEND data for developmental and reproductive toxicity studies

P21-01 Challenges and practical examples in creation of SEND data for developmental and reproductive toxicity studies

COVID-19 vaccination in pregnant and lactating women

Introduction: The COVID-19 pandemic significantly changed the lifestyle of pregnant women. Pregnant women with COVID-19 are more likely to suffer from severe disease, as well as unfavorable pregnancy and childbirth. Currently, there is no causal treatment for this disease available, so attention should be paid to preventing infection with vaccines.
 Aim of the study: A review of the literature on the influence of COVID-19 vaccines on the course of pregnancy and summary of recommendations regarding the use of COVID-19 vaccines during pregnancy and breastfeeding.
 State of knwoledge: Three types of COVID-19 vaccines are most commonly used: mRNA vaccines, vector vaccines as well as subunit vaccines. In preclinical developmental and reproductive toxicity studies in animal models, there were no alarming safety signals, and observations of vaccinated pregnant women did not reveal any complications with respect to the course of pregnancy and development of the fetus. No cases of neonatal death have been reported in the first 28 days after birth. Most of the side effects following vaccination, such as injection site pain or tenderness, fatigue, fever or muscle pain, were moderate and resolved within 24 hours. The current research results confirm a positive immune response in pregnant women. Moreover, it is important that the presence of antibodies in the umbilical cord blood makes it possible to protect and reduce the risk of SARS-CoV-2 infection of the newborn.
 Summary: All pregnant women, irrespective of trimester, and breastfeeding mothers are advised to administer a booster dose of the COVID-19 vaccine within an appropriate period of time after the primary vaccination schedule.

Risk Assessment of the Growth Inhibitor Bonzi with the Active Substance Paclobutrazol

Bonzi is a new plant growth regulator containing the active ingredient paclobutrazol of the triazole chemical class. Bonzi is for use on ornamental plants, such as Chrysanthemum, Perennial Plants, Bedding Plants, Foliage Plants, Geraniums, Hibiscus and Azaleas, in nurseries and greenhouses.
 
 VKM was requested by the Norwegian Food Safety Authority to consider the potential of Bonzi and paclobutrazol to induce reproductive effects in humans; in particular the relative sensitivity and relation between maternal effects and the effects on the offspring; and to what extent cleft palate observed in developmental studies in rat can be regarded as a specific teratogenic effect of relevance for humans. The risk assessment was finalized in a meeting in VKM’s Scientific Panel on Plant Protection Products on May 24. 2013.
 VKM’s conclusions are as follows:
 
 No adverse effect on fertility or reproductive performance was seen in rats. VKM concluded that the incidences of twisted snout observed in the F1 and F2 offspring of paclobutrazol treated rats are not likely to represent a developmental alteration, but rather an unspecific toxic effect.
 
 Marked maternal toxicity was seen in rats above 250 mg/kg bw/day, while partially ossified 7th cervical transverse processes and supernumerary 14th ribs were found in the offspring at 10 - 40 mg/kg/day. VKM concluded that the latter should be regarded as a direct teratogenic effect of paclobutrazol.
 
 Furthermore, VKM concluded that the data from the developmental toxicity studies are inconclusive regarding the effect on cleft palate development in rat foetuses.
 
 VKM proposes a NOAEL of 2.5 mg/kg bw/day for paclobutrazol based on a developmental toxicity study in rats.

Endoplasmic reticulum stress-controlled autophagic pathway promotes polystyrene microplastics-induced myocardial dysplasia in birds

In complex ecosystems, birds are generally long-lived and occupy high trophic positions, making them good bioindicators for monitoring environmental contaminants. The effects of microplastics (MPs) on myocardial development in bird is currently unknown. Chicks, as a high trophic level terrestrial bird, may be more affected by MPs exposure and. Therefore, we established an in vivo model of chicks exposed to different concentrations of polystyrene microplastics (PS-MPs) and selected 12-day-old chicken embryos in vitro to extract primary cardiomyocytes to further investigate the potential molecular mechanisms of the effect of PS-MPs on myocardial development in birds. Histopathological observations revealed that the PS-MPs treated exhibited loose and irregular myocardial arrangement, large cell gaps and broken myocardial fiber bundles. More mechanistically, TnnT2, Nkx2-5, Gata4, TBX5 and ACTN2 were down-regulated, endoplasmic reticulum (ER) stress markers GRP78, PERK, eIF2α, IRE1, ATF4, ATF6 and CHOP were overexpressed, autophagy-related genes LC3, ATG5, Beclin1 and P62 were down-expressed after PS-MPs exposure, and the addition of 4PBA effectively deregulated the above aberrant expression. Hence, our report indicated that PS-MPs induced myocardial dysplasia in birds is mainly attributed to the ER stress-mediated autophagic pathway. This provided data supporting the protection of birds from the health risks of MPs pollution. More critically, the study of cardiac developmental toxicity in birds may help to better explain or solve the problem of MPs pollution in complex ecosystems.

Developmental and reproduction toxicity of piperonyl butoxide part 2 developmental safety of piperonyl butoxide in the NZW rabbit

Piperonyl butoxide (PBO) was developed in the 1940s. PBO increases the effectiveness of pyrethrins, thus it is called a synergist. Herein, the findings from a guideline developmental toxicity study in rabbits conducted in 1986 are reported. Inseminated New Zealand White rabbits were randomly assigned to a control and three treatment groups of 16 does each. Dose levels of 50, 100 and 200 mg/kg/day were selected based on a dosage-range study to avoid excessive maternal toxicity and administered orally (gavage) as a single daily dose on days 7–19 of gestation at a volume of 0.5 mL/kg. The control group received the vehicle only, Mazola® corn oil. Cesarean sections were performed on all surviving females on gestation day 29 and fetuses were evaluated. Survival for all study groups was 100%. Treatment-related maternotoxicity was manifested at the 100 and 200 mg/kg/day levels as decreased defecation and dose-related body weight losses during the treatment period (gestation days 7–13 and 7–19). The Cesarean section parameter values and fetal morphological observations of the treated groups did not differ significantly from the concurrent control group and were within the historical control range for this rabbit strain. No maternal or fetal adverse effects were seen at the 50 mg/kg/day dose level. Although maternal toxicity resulting from treatment was apparent at the 100 and 200 mg/kg/day dose levels, neither fetotoxicity nor teratogenicity were elicited in rabbits by piperonyl butoxide at dose levels as high as 200 mg/kg/day.

Developmental and reproduction toxicity of piperonyl butoxide part 1 developmental safety of piperonyl butoxide in the CD® (Sprague Dawley) rat

Developed as an insecticide synergist in the early 1940s, PBO increases the effectiveness of pyrethrins. Herein, the findings from a guideline developmental toxicity study in rat conducted in 1991 are reported. Timed-pregnant CD® (Sprague Dawley) rats were randomly assigned to a control and three treatment groups of 25 females each. A single daily dose of 200, 500 and 1000 mg/kg/day was administered orally (gavage) on days 6–15 of gestation. A vehicle group received deionized water. Cesarean sections were performed on all surviving females on gestation day 21 and fetuses were evaluated. All rats survived to GD 21 of gestation. Pregnancy rates in each group ranged from 88 % to 96 %. One dam in the 500 mg/kg/day dose had a single conceptus litter (one early resorption). Adverse clinical observations (urogenital wetness and staining) occurred in the 1000 mg/kg/day dose group. Maternal body weight decrease and food reductions occurred over the dosing period in the 500 and 1000 mg/kg/day groups. There were no treatment-related maternal necropsy findings. Terminal body weights and gravid uterine weights were comparable among the groups. Corrected body weight gain was decreased (>10 %) at 500 and 1000 mg/kg/day. Increased liver weights and relative liver weights were observed in the 1000 mg/kg/day dose group. There were no treatment-related effects on early resorptions, late resorptions, live fetuses per litter or sex ratio, or fetal weight per litter among the dose groups and no fetal malformations or variations attributed to PBO at any dose level.

Is Mixtures' Additivity Supported by Empirical Data? A Case Study of Developmental Toxicity of PFOS and 6:2 FTS in Wildtype Zebrafish Embryos.

Per- and polyfluoroalkyl substances (PFASs) are a major priority for many federal and state regulatory agencies charged with monitoring levels of emerging contaminants in environmental media and setting health-protective benchmarks to guide risk assessments. While screening levels and toxicity reference values have been developed for numerous individual PFAS compounds, there remain important data gaps regarding the mode of action for toxicity of PFAS mixtures. The present study aims to contribute whole-mixture toxicity data and advance the methods for evaluating mixtures of two key components of aqueous film-forming foams: perfluorooctanesulfonic acid (PFOS), and 6:2 fluorotelomer sulfonic acid (6:2 FTS). Wildtype (AB) zebrafish embryos were exposed to PFOS and 6:2 FTS, both as individual components and as binary mixtures, from 2 to 122 h post-fertilization. Five treatment levels were selected to encompass environmentally relevant exposure levels. Experimental endpoints consisted of mortality, hatching, and developmental endpoints, including swim bladder inflation, yolk sac area, and larval body length. Results from dose–response analysis indicate that the assumption of additivity using conventional points of departure (e.g., NOAEL, LOAEL) is not supported for critical effect endpoints with these PFAS mixtures, and that the interactions vary as a function of the dose range. Alternative methods for quantifying relative potency are proposed, and recommendations for additional investigations are provided to further advance assessments of the toxicity of PFAS mixtures to aquatic organisms.

The Postnatal Resolution of Developmental Toxicity Induced by Pharmacological Diacylglycerol Acyltransferase 2 (DGAT2) Inhibition During Gestation in Rats.

Ervogastat (PF-06865571) is a small molecule diacylglycerol acyltransferase 2 (DGAT2) inhibitor being developed for the oral treatment of nonalcoholic steatohepatitis (NASH) with liver fibrosis. DGAT2 is a key enzyme in triglyceride synthesis in tissues and in regulating energy metabolism. Fertility and developmental toxicity studies with ervogastat were conducted in female rats and rabbits. There were no effects on female rat fertility or rabbit embryo-fetal development. Administration of ervogastat to pregnant rats during organogenesis reduced fetal weight and caused higher incidences of bent bones in fetuses that were shown to resolve by postnatal day 28 and were therefore considered to be transient variations secondary to developmental delay. Extended dosing in rats through the end of gestation and lactation (pre- and post-natal development study) caused impaired skin development, reduced offspring viability, and growth retardation. The spectrum of developmental effects in rats is consistent with the intended pharmacology (altered triglyceride metabolism) and the transient nature of the skeletal findings, along with the late gestational window of sensitivity for the effects on skin barrier development, reduce the concern for potential adverse developmental effects following unintended early gestational exposure to ervogastat in humans where treatment can be discontinued once pregnancy is determined.

Developmental exposure to the brominated flame retardant DE-71 reduces serum thyroid hormones in rats without hypothalamic-pituitary-thyroid axis activation or neurobehavioral changes in offspring

Polybrominated diphenyl ethers (PBDEs) are legacy flame retardants for which human exposure remains ubiquitous. This is of concern since these chemicals can perturb development and cause adverse health effects. For instance, DE-71, a technical mixture of PBDEs, can induce liver toxicity as well as reproductive and developmental toxicity. DE-71 can also disrupt the thyroid hormone (TH) system which may induce developmental neurotoxicity indirectly. However, in developmental toxicity studies, it remains unclear how DE-71 exposure affects the offspring's thyroid hormone system and if this dose-dependently relates to neurodevelopmental effects. To address this, we performed a rat toxicity study by exposing pregnant dams to DE-71 at 0, 40 or 60 mg/kg/day during perinatal development from gestational day 7 to postnatal day 16. We assessed the TH system in both dams and their offspring, as well as potential hearing and neurodevelopmental effects in prepubertal and adult offspring. DE-71 significantly reduced serum T4 and T3 levels in both dams and offspring without a concomitant upregulation of TSH, thus inducing a hypothyroxinemia-like effect. No discernible effects were observed on the offspring's brain function when assessed in motor activity boxes and in the Morris water maze, or on offspring hearing function. Our results, together with a thorough review of the literature, suggest that DE-71 does not elicit a clear dose-dependent relationship between low serum thyroxine (T4) and effects on the rat brain in standard behavioral assays. However, low serum TH levels are in themselves believed to be detrimental to human brain development, thus we propose that we lack assays to identify developmental neurotoxicity caused by chemicals disrupting the TH system through various mechanisms.

Review of embryo-fetal developmental toxicity studies performed for pharmaceuticals approved by FDA in 2020 and 2021.

103 novel drugs were approved by the FDA in 2020–2021. Embryofetal development (EFD) studies were conducted for 76 % of these approvals. For the majority of drugs, EFD studies were conducted in rats and rabbits. Both species were equally sensitive to developmental toxicity, but the rabbit was slightly more sensitive to maternal toxicity at the same systemic exposure level. Nonetheless, 68 % of drugs showed more than a 2-fold difference in the low adverse effect level for developmental toxicity between the rat and rabbit. Previous reviews in this series compiled information on EFD studies for all small molecule pharmaceuticals approved since 2014 and for all therapeutic monoclonal antibodies approved to date. The use of non-human primates for the developmental toxicity testing of biopharmaceuticals has fallen over recent years (22 % of biologics license applications (BLAs) for 2020–2021, compared with 62 % for 2002–2015), with more biopharmaceuticals now tested in rodents (37 % of BLAs for 2020–2021). While the Pregnancy and Lactation Labeling Rule (PLLR), adopted in 2014, has brought consistency to the presentation of EFD data in drug labels, prescribers complain that the pregnancy section of current drug labels is neither concise nor clear. The FDA has pledged to address the concerns of clinicians in a future revision of the PLLR rule. The recommendations on risk assessment in the recently revised ICHS5(R3) guideline could be incorporated into the PLLR rule to remove extraneous nonclinical details from the label with the aim of facilitating rapid understanding by the practitioner.

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.

Current activities between the DevTox Berlin workshops and the Japanese Teratology Society Terminology Committee in harmonizing the terminology for classifying anomalies in laboratory animals in developmental toxicity studies: Report from the Satellite Workshop of the 60th Annual Meeting of the Japanese Teratology Society.

In recent years, the Japanese Teratology Society has worked with the DevTox Berlin Workshops project to provide internationally consistent terminology for teratogenic effects. This paper summarizes a satellite workshop of the 60th Annual Meeting of the Japanese Teratology Society, which was entitled "Current activities between DevTox Berlin Workshops to develop a harmonized terminology for classifying anomalies in laboratory animals in developmental toxicity studies." The Japanese Teratology Society - Laboratory Animal Terminology Project (JTS-LATP) reviewed "gray zone" anomalies and focused on developing criteria for reclassifying a large number of gray zone anomalies to clarify them and to make it easier to judge fetal categories. This effort will lead to international agreement, based on shared conceptions. The present article aimed to provide the reader with a summary of the issues discussed at the 2020 satellite meeting, which included discussions on open issues from the DevTox Berlin Workshops, ongoing work by the JTS-LATP on gray zone (GZ) anomalies, current industrial concerns, and future challenges.