Regulatory Forum Opinion Piece: Carcinogen Risk Assessment: The Move from Screens to Science

Recent progress in machine learning approaches for predicting carcinogenicity in drug development

INTRODUCTION

This review explores the transformative impact of machine learning (ML) on carcinogenicity prediction within drug development. It discusses the historical context and recent advancements, emphasizing the significance of ML methodologies in overcoming challenges related to data interpretation, ethical considerations, and regulatory acceptance.

AREAS COVERED

The review comprehensively examines the integration of ML, deep learning, and diverse artificial intelligence (AI) approaches in various aspects of drug development safety assessments. It explores applications ranging from early-phase compound screening to clinical trial optimization, highlighting the versatility of ML in enhancing predictive accuracy and efficiency.

EXPERT OPINION

Through the analysis of traditional approaches such as in vivo rodent bioassays and in vitro assays, the review underscores the limitations and resource intensity associated with these methods. It provides expert insights into how ML offers innovative solutions to address these challenges, revolutionizing safety assessments in drug development.

Pathologists' perspective on the study design, analysis, and interpretation of proliferative lesions in lifetime and prenatal rodent carcinogenicity bioassays of aspartame

Aspartame, an artificial sweetener commonly used as a sugar substitute, is currently authorized for use in more than 100 countries. Hundreds of studies, conducted in various countries dating back to the 1970s, have shown that aspartame is safe at real-world exposure levels. Furthermore, multiple human epidemiology studies have provided no indication that consumption of aspartame induces cancer. Given the continued controversy surrounding the Ramazzini Institute's (RI) studies suggesting that aspartame is a carcinogenic hazard in rodents and evaluation by the International Agency for Research on Cancer, this report aims to provide the perspective of experienced pathologists on publicly available pathology data regarding purported proliferative lesions in liver, lung, lymphoid organs, and mammary gland as well as their implications for human risk assessment as reported for three lifetime rodent carcinogenicity bioassays of aspartame conducted at the RI. In the authors' view, flaws in the design, methodology and reporting of the RI aspartame studies limit the utility of the data sets as evidence that this agent represents a carcinogenic hazard. Therefore, all three RI studies, and particularly the accuracy of their pathology diagnoses and interpretations, should be rigorously reviewed by qualified and experienced veterinary toxicologic pathologists in assessing aspartame's carcinogenic risk.

Evaluation of mutagenesis, necrosis and apoptosis induced by omeprazole in stomach cells of patients with gastritis

Background

Gastritis is a superficial and prevalent inflammatory lesion that is considered a public health concern once can cause gastric ulcers and gastric cancer, especially when associated with Helicobacter pylori infection. Proton pump inhibitors, such as omeprazole, are the most widely used drugs to treat this illness. The aim of the study was evaluate cytogenetic effects of omeprazole in stomach epithelial cells of patients with gastritis in presence and absence of H. pylori, through cytogenetic biomarkers and catalse and superoxide dismutase analysis.

Methods

The study included 152 patients from the Gastroenterology Outpatient Clinic of Hospital Getúlio Vargas, Teresina—Brazil, that reported continuous and prolonged omeprazole use in doses of 20, 30 and 40 mg/kg. The participants were divided into groups: (1) patients without gastritis (n = 32); (2) patients without gastritis but with OME use (n = 24); (3) patients with gastritis (n = 26); (4) patients with gastritis undergoing OME therapy (n = 26); (5) patients with gastritis and H. pylori (n = 22) and (6) patients with gastritis and H. pylori on OME therapy (n = 22).

Results

OME induced cytogenetic imbalance in the stomach epithelium through the formation of micronuclei (group 6 > 1, 2, 3, 4, 5; group 5 > 1, 2, 3; group 4 > 1, 2, 3); bridges (groups 4 and 6 > 1, 2, 3, 5 and group 2 > 3, 5); buds (groups 2,4,6 > , 1, 3, 5); binucleated cells (group 6 > 1, 2, 3, 4, 5; group 4 > 1, 2, 3); (groups 2 and 3 > 1); picnoses (group 6 > 1, 2, 3, 4, 5), groups 2 and 5 > 1, 3; group 4 > 1, 2, 3, 5); cariorrexis (groups 6 and 4 > 1, 2, 3, 5; groups 2, 3, 5 > 1) and karyolysis (groups 2, 4, and 6 > 1, 3, 5; groups 3 and 5 > 1). The OME cytogenetic instability was associated with H. pylori infection, indicating clastogenic/aneugenic effects, chromosomes alterations, gene expression changes, cytotoxicity and apoptosis.

Conclusions

The cytogenetic changescan be attributed to several mechanisms that are still unclear, including oxidative damage, as observed by increased catalase and superoxide dismutase expresion. Positive correlations between antioxidant enzymes were found with micronuclei formation, and were negative for picnoses. Thus, the continuous and prolonged omeprazole use induces genetic instability, which can be monitored through cytogenetic analyzes, as precursor for gastric cancer.

Antioxidative defense against omeprazole-induced toxicogenetical effects in Swiss mice

BACKGROUND

Omeprazole (OME), a most frequently used proton pump inhibitor in gastric acidosis, is evident to show many adverse effects, including genetic instability. This study evaluated toxicogenic effects of OME in Mus musculus.

METHODS

For this study, 40 male Swiss mice were divided into 8 groups (n = 5) and treated with OME at doses of 10, 20, and 40 mg/kg and/or treated with the antioxidants retinol palmitate (100 IU/kg) and ascorbic acid (2.0 μM/kg). Cyclophosphamide 50 mg/kg, (cytotoxic agent) and the vehicle were served as positive and negative control group, respectively. After 14 days of treatment, the stomach cells along with the bone marrow and peripheral blood lymphocytes were collected and submitted to the comet assay (alkaline version) and micronucleus test. Additionally, hematological and biochemical parameters of the animals were also determined inspect of vehicle group.

RESULTS

The results suggest that OME at all doses induced genotoxicity and mutagenicity in the treated cells. However, in association with the antioxidants, these effects were modulated and/or inhibited along with a DNA repair capacity.

CONCLUSIONS

Taken together, antioxidants (such as retinol palmitate and ascorbic acid) may be one of the best options to counteract OME-induced cytogenetic instability.

Pharmacological Effects and Toxicogenetic Impacts of Omeprazole: Genomic Instability and Cancer

Omeprazole (OME) is commonly used to treat gastrointestinal disorders. However, long-term use of OME can increase the risk of gastric cancer. We aimed to characterize the pharmacological effects of OME and to correlate its adverse effects and toxicogenetic risks to the genomic instability mechanisms and cancer-based on database reports. Thus, a search (till Aug 2019) was made in the PubMed, Scopus, and ScienceDirect with relevant keywords. Based on the study objective, we included 80 clinical reports, forty-six in vitro, and 76 in vivo studies. While controversial, the findings suggest that long-term use of OME (5 to 40 mg/kg) can induce genomic instability. On the other hand, OME-mediated protective effects are well reported and related to proton pump blockade and anti-inflammatory activity through an increase in gastric flow, anti-inflammatory markers (COX-2 and interleukins) and antiapoptotic markers (caspases and BCL-2), glycoprotein expression, and neutrophil infiltration reduction. The reported adverse and toxic effects, especially in clinical studies, were atrophic gastritis, cobalamin deficiencies, homeostasis disorders, polyp development, hepatotoxicity, cytotoxicity, and genotoxicity. This study highlights that OME may induce genomic instability and increase the risk of certain types of cancer. Therefore, adequate precautions should be taken, especially in its long-term therapeutic strategies and self-medication practices.

Ascorbic acid and retinol palmitate modulatory effect on omeprazole-induced oxidative damage, and the cytogenetic changes in S. cerevisiae and S180 cells

Omeprazole (OM), a prototype proton pump inhibitor, oxidizes thiol groups and induces DNA damage. The aim of this study was to evaluate the oxidative effects of omeprazole and its interactions with ascorbic acid (AA, 50 μM) and retinol palmitate (RP) in proficient and deficient Saccharomyces cerevisiae strains, as well as levels of cytogenetic damage in Sarcoma 180 (S180) cells. Omeprazole was tested at concentrations of 10, 20 and 40 μg/mL, whereas H₂O₂ (10 mM), cyclophosphamide (20 mg/mL), and saline (0.9% NaCl solution) were employed as stressor, positive control, and negative control, respectively. Results revealed that omeprazole concentration-dependently induces oxidative effects in S. cerevisiae strains. However, omeprazole co-treated with ascorbic acid (50 μM) and retinol palmitate (100 IU) significantly modulated the oxidative damage inflected on the S. cerevisiae strains. Furthermore, omeprazole did not produce micronucleus formation and chromosomal bridges in S180 cells, but induced shoots. Significant increase in karyolysis and karyorrhexis were also observed with the omeprazole treated groups, which was modulated by co-treatment with ascorbic acid and retinol palmitate. Taken all together, it is suggested that ascorbic acid and retinol palmitate can substantially modulate the oxidative damage caused by omeprazole on the S. cerevisiae strains, however, much precaution is recommended with omeprazole and antioxidant co-treatment.

Toxicogenetic study of omeprazole and the modulatory effects of retinol palmitate and ascorbic acid on Allium cepa

Omeprazole (OME) is a proton pump inhibitor used for the treatment of various gastric and intestinal disease; however, studies on its effects on the genetic materials are still restricted. The present study aimed to evaluate possible toxicogenic effects of OME in Allium cepa meristems with the application of cytogenetic biomarkers for DNA damage, mutagenic, toxic and cytotoxic effects. Additionally, retinol palmitate (RP) and ascorbic acid (AA) were also co-treated with OME to evaluate possible modulatory effects of OME-induced cytogenetic damages. OME was tested at 10, 20 and 40 μg/mL, while RP and AA at 55 μg/mL and 352.2 μg/mL, respectively. Copper sulphate (0.6 μg/mL) and dechlorinated water were used as positive control and negative control, respectively. The results suggest that OME induced genotoxicity and mutagenicity in A. cepa at all tested concentrations. It was noted that cotreatment of OME with the antioxidant vitamins RP and/or AA significantly (p < 0.05) inhibited and/or modulated all toxicogenic damages induced by OME. These observations demonstrate their antigenotoxic, antimutagenic, antitoxic and anticitotoxic effects in A. cepa. This study indicates that application of antioxidants may be useful tools to overcome OME-induced toxic effects.

Glyphosate toxicity and carcinogenicity: a review of the scientific basis of the European Union assessment and its differences with IARC

Glyphosate is the most widely used herbicide worldwide. It is a broad spectrum herbicide and its agricultural uses increased considerably after the development of glyphosate-resistant genetically modified (GM) varieties. Since glyphosate was introduced in 1974, all regulatory assessments have established that glyphosate has low hazard potential to mammals, however, the International Agency for Research on Cancer (IARC) concluded in March 2015 that it is probably carcinogenic. The IARC conclusion was not confirmed by the EU assessment or the recent joint WHO/FAO evaluation, both using additional evidence. Glyphosate is not the first topic of disagreement between IARC and regulatory evaluations, but has received greater attention. This review presents the scientific basis of the glyphosate health assessment conducted within the European Union (EU) renewal process, and explains the differences in the carcinogenicity assessment with IARC. Use of different data sets, particularly on long-term toxicity/carcinogenicity in rodents, could partially explain the divergent views; but methodological differences in the evaluation of the available evidence have been identified. The EU assessment did not identify a carcinogenicity hazard, revised the toxicological profile proposing new toxicological reference values, and conducted a risk assessment for some representatives uses. Two complementary exposure assessments, human-biomonitoring and food-residues-monitoring, suggests that actual exposure levels are below these reference values and do not represent a public concern.

Evaluation of toxic, cytotoxic and genotoxic effects of phytol and its nanoemulsion

Phytol (PYT) is a diterpenoid having important biological activity. However, it is a water non-soluble compound. This study aims to prepare PYT nanoemulsion (PNE) and evaluation of toxic, cytotoxic and genotoxic activities of PYT and PNE. For this, the PNE was prepared by the phase inversion method. The cytotoxicity test was performed in Artemia salina, while toxicity, cytotoxicity and genotoxicity in Allium cepa at concentrations of 2, 4, 8 and 16 mM. Potassium dichromate and copper sulfate were used as positive controls for the tests of A. salina and A. cepa, respectively. In addition, an adaptation response was detected in A. cepa by using the comet assay. The results suggest that both PYT and PNE exhibited toxic and cytotoxic effects at 4-16 mM in either test system, while genotoxicity at 2-16 mM in A. cepa. PNE exhibited more toxic, cytotoxic and genotoxic effects at 8 and 16 mM than the PYT. However, both PYT and PNE at 2 and 4 mM decreased the index and frequency of damage in A. cepa after 48 and 72 h, suggesting a possible adaptation response or DNA damage preventing capacity. Nanoemulsified PYT (PNE) may readily cross the biological membranes with an increase in bioavailability and produce more toxic, cytotoxic and genotoxic effects in the used test systems.