Toxicovigilance 2.0 - modern approaches for the hazard identification and risk assessment of toxicants in human beings: A review

The attempt to define toxicovigilance can be based on defining its fundamental principles: prevention of infections with toxic substances, collecting information on poisonings, both in terms of their sources and side effects, and confirming poisonings, with the aim of improving treatment. Substances referred to include both those originating from animal bites, ingested inadvertently, and those resulting from environmental poisoning in industrial regions of countries, etc. In this review, we provide information about the crucial function of poison control centres in toxicovigilance, the importance of incorporating big data analytics and artificial intelligence to streamline toxicovigilance processes, and examples of toxicovigilance in different countries. In conclusion, we will present the direction that modern toxicovigilance should take, incorporating available artificial intelligence methods to maximise efficiency.

Antidotes in Clinical Toxicology-Critical Review

Poisoning and overdose are very important aspects in medicine and toxicology. Chemical weapons pose a threat to civilians, and emergency medicine principles must be followed when dealing with patients who have been poisoned or overdosed. Antidotes have been used for centuries and modern research has led to the development of new antidotes that can accelerate the elimination of toxins from the body. Although some antidotes have become less relevant due to modern intensive care techniques, they can still save lives or reduce the severity of toxicity. The availability of antidotes is crucial, especially in developing countries where intensive care facilities may be limited. This article aims to provide information on specific antidotes, their recommended uses, and potential risks and new uses. In the case of poisoning, supportive therapies are most often used; however, in many cases, the administration of an appropriate antidote saves the patient's life. In this review, we reviewed the literature on selected antidotes used in the treatment of poisonings. We also characterised the antidotes (bio)chemically. We described the cases in which they are used together with the dosage recommendations. We also analysed the mechanisms of action. In addition, we described alternative methods of using a given substance as a drug, an example of which is N-acetylcysteine, which can be used in the treatment of COVID-19. This article was written as part of the implementation of the project of the Polish Ministry of Education and Science, "Toxicovigilance, poisoning prevention, and first aid in poisoning with xenobiotics of current clinical importance in Poland", grant number SKN/SP/570184/2023.

Abstract 449: Discovery of novel MTA-cooperative PRMT5 inhibitors as targeted therapeutics for MTAP-deleted cancers

Homozygous deletions of p16/CDKN2a (cyclin dependent kinase inhibitor 2A) locus are prevalent in cancer and often involve co-deletion of adjacent genes. Metabolic gene MTAP (methylthioadenosine phosphorylase) is localized at the 9p21 chromosome in the close proximity to p16/CDKN2A tumor-suppressor locus. Co-deletion of MTAP may be observed in 80-90% of all tumors harboring homozygous deletion of CDKN2A, which represents 10 - 15% of all human tumors. Many of these tumor types, such as non-small cell lung cancer, pancreatic adenocarcinoma, glioblastoma or mesothelioma are associated with poor prognosis, representing a significant unmet medical need. MTAP deletion results in a massive accumulation of methylthioadenosine (MTA) in cells. MTA in high concentrations is a very selective inhibitor of PRMT5 methyltransferase, competitive for the substrate: S-adenosylmethionine (SAM). Accumulation of MTA in cells with MTAP deletion causes partial inhibition of the methylation activity of PRMT5, which in turn reduces the level of symmetric arginine dimethylation of the whole proteome, and thus an increased sensitivity of cells to modulation of methylosome activity. Therapeutic targeting of PRMT5 in homozygous MTAP-deleted cancers constitute a promising strategy of selective killing of genetically defined cancer cells. Ryvu has identified a series of MTA-cooperative PRMT5 inhibitors which have good drug-like physicochemical properties and block methyltransferase activity with nanomolar IC50 values. Structurally enabled hit generation and optimization allowed quick expansion and delivery of several generations of compounds with novel IP, high target engagement in cells and selective potency in MTAP-deleted cell lines. Ryvu compounds selectively inhibit growth of MTAP-deleted cancer cells in prolonged 3D culture, which strongly correlates with inhibition of PRMT5-dependent protein symmetric dimethylation (SDMA) in those cells. Selectivity between effects observed in MTAP-deleted and WT cells exceeds 100-fold both for SDMA and growth inhibition. The DMPK profile of these compounds allows for oral administration, which enables testing antitumor activity in MTAP null tumor xenograft-bearing mice. Efficacy studies with our lead compound resulted in demonstration of tumor growth inhibition in MTAP -/- model, accompanied by significant inhibition of target proximal PD biomarker.  Overall, these studies provide a rationale for further optimization of our chemical series of MTA-cooperative PRMT5 inhibitors towards a clinical candidate. 

Citation Format: Anna Bartosik, Adam Radzimierski, Aneta Bobowska, Oleksandr Levenets, Agata Stachowicz, Kamil Kuś, Kinga Michalik, Katarzyna Banaszak, Monika Madej, Marta Skoda, Kamila Kozłowska-Tomczyk, Igor Tomczyk, Karolina Pyziak, Dobrosława Krzemień, Mirosława Gładysz, Paulina Podkalicka, Aniela Gołas, Karolina Gluza, Grzegorz Satała, Andrzej Gondela, Marta Sowińska, Nicolas Boutard, Agata Chłopek, Aleksandra Więckowska, Daria Szukiel, Grzegorz Ćwiertnia, Iana Levenets, Karol Zuchowicz, Klara Korta-Piątek, Marcin Nowogródzki, Marek Wronowski, Marianna Girardi, Mateusz Świrski, Oleksandr Popika, Paulina Niedziejko-Ćwiertnia, Pierpaolo Cordone, Przemysław Wyrębek, Quỳnh Vũ, Sujit Sasmal, Svitlana Sukhomlinova, Magdalena Miodek, Jacek Faber, Anna Kowal-Chwast, Róża Starczak, Sanja Novak Ratajczak, Agnieszka Świrska, Dawid Gogola, Paweł Guzik, Martin Swarbrick, Mateusz Nowak. Discovery of novel MTA-cooperative PRMT5 inhibitors as targeted therapeutics for MTAP-deleted cancers  [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 449.

Abstract 1806: Discovery of novel MTA-cooperative PRMT5 inhibitors as a targeted therapeutics for MTAP deleted cancers

Targeting PRMT5 in MTAP-deleted tumors in a synthetic lethal approach represents a promising antitumor strategy across many tumor types. Metabolic gene MTAP is localized at the 9p21 chromosome in the close proximity to CDKN2A tumor-suppressor locus. Co-deletion of MTAP may be observed in 80-90% of all tumors harboring homozygous deletion of CDKN2A, which represents 10-15% of all human tumors. MTAP deletion results in a massive accumulation of methylotioadenosine (MTA) in cells. MTA in high concentrations is a selective inhibitor of PRMT5 type II methyltransferase. PRMT5 conjugated with WD-repeat containing protein (WDR77) builds methylosome, which regulates essential cellular functions via symmetric demethylation (SDMA) of target proteins involved in regulation of gene expression, RNA splicing, signal transduction, metabolism and other functions. Accumulation of MTA in cells with MTAP deletion causes a partial inhibition of the methylation activity of PRMT5, which in turn reduces the level of symmetric arginine dimethylation of the whole proteome, and thus an increased sensitivity of cells to modulation of the methylosome activity. Therapeutic targeting of PRMT5 in homozygous MTAP-deleted cancers constitute a promising strategy of selective killing of genetically defined cancer cells. Currently available clinical stage PRMT5 small molecule inhibitors are not MTA-cooperative and therefore are not selective in tumors harboring MTAP deletion. Here we present MTA-cooperative PRMT5 inhibitors, which selectively inhibit the growth of MTAP deleted cancer cells. Ryvu has identified a series of MTA-cooperative PRMT5 inhibitors which have good drug-like physicochemical properties and block methyltransferase activity with nanomolar IC50 values. Ryvu compounds selectively inhibit growth of MTAP deleted cancer cells in prolonged 3D culture, which strongly correlates with inhibition of PRMT5-dependent protein symmetric demethylation (SDMA) in those cells. Selectivity between effects observed in MTAP deleted and WT cells exceeds 100-fold both for SDMA and growth inhibition. The DMPK profile of these compounds allows for oral administration, which enables testing dose-dependent antitumor activity in MTAP null tumor xenograft-bearing mice. Overall, these studies provide rationale for further optimization of chemical series towards clinical candidate. 

Citation Format: Oleksandr Levenets, Anna Bartosik, Marta Sowińska, Karol Zuchowicz, Sujit Sasmal, Klara Korta-Piątek, Adam Radzimierski, Paulina Niedziejko, Oleksandr Popika, Mateusz Świrski, Agata Stachowicz, Maciej Mikulski, Magdalena Sieprawska-Lupa, Katarzyna Banaszak, Kinga Michalik, Kamil Kuś, Monika Madej, Adrian Podkowa, Karolina Gluza, Grzegorz Satała, Ewelina Cieluch, Dobrosława Krzemień, Andrzej Gondela, Grzegorz Ćwiertnia, Marek Wronowski, Nicolas Boutard, Aleksandra Więckowska, Joanna Zezula, Justyna Jabłońska, Mirosława Gładysz, Igor Tomczyk, Jacek Faber, Marcin Serocki, Eliza Drwal, Kamila Kozłowska-Tomczyk, Marta Skoda, Martin Swarbrick, Krzysztof Brzózka, Mateusz Nowak. Discovery of novel MTA-cooperative PRMT5 inhibitors as a targeted therapeutics for MTAP deleted cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1806.

Peptide Dendrimers with Non-Symmetric Bola Structure Exert Long Term Effect on Glioblastoma and Neuroblastoma Cell Lines

BACKGROUND

Glioblastoma (GBM) is the most common malignant tumor of the central nervous system (CNS). Neuroblastoma (NB) is one of the most common cancers of childhood derived from the neural crest cells. The survival rate for patients with GBM and high-risk NB is poor; therefore, novel therapeutic approaches are needed. Increasing evidence suggests a dual role of redox-active compounds in both tumorigenesis and cancer treatment. Therefore, in this study, polyfunctional peptide-based dendrimeric molecules of the bola structure carrying residues with antiproliferative potential on one side and the antioxidant residues on the other side were designed.

METHODS

We synthesized non-symmetric bola dendrimers and assessed their radical scavenging potency as well as redox capability. The influence of dendrimers on viability of rat primary cerebellar neurons (CGC) and normal human astrocytes (NHA) was determined by propidium iodide staining and cell counting. Cytotoxicity against human GBM cell lines, T98G and LN229, and NB cell line SH-SY5Y was assessed by cell counting and colony forming assay.

RESULTS

Testing of CGC and NHA viability allowed to establish a range of optimal dendrimers structure and concentration for further evaluation of their impact on two human GBM and one human NB cell lines. According to ABTS, DPPH, FRAP, and CUPRAC antioxidant tests, the most toxic for normal cells were dendrimers with high charge and an excess of antioxidant residues (Trp and PABA) on both sides of the bola structure. At 5 μM concentration, most of the tested dendrimers neither reduced rat CGC viability below 50-40%, nor harmed human neurons (NHA). The same dose of compounds 16 or 22, after 30 min treatment decreased the number of SH-SY5Y and LN229 cells, but did not affect the number of T98G cells 48 h post treatment. However, either compound significantly reduced the number of colonies formed by SH-SY5Y, LN229, and T98G cells measured 14 days after treatment.

CONCLUSIONS

Peptide dendrimers with non-symmetric bola structure are excellent scaffolds for design of molecules with pro/antioxidant functionality. Design of molecules with an excess of positive charges and antioxidant residues rendered molecules with high neurotoxicity. Single, 30 min exposition of the GBM and NB cell lines to the selected bola dendrimers significantly suppressed their clonogenic potential.

Bioinspired Amphiphilic Peptide Dendrimers as Specific and Effective Compounds against Drug Resistant Clinical Isolates of E. coli

Evolution-derived natural compounds have been inspirational for design of numerous pharmaceuticals, e.g., penicillins and tetracyclines. Herein, we present a bioinspired strategy to design peptide dendrimers for the effective therapy of E. coli infections where the selection of appropriate amino acids and the mode of their assembly are based on the information gained from research on membranolytic natural antimicrobial peptides (AMP's). On the molecular level two opposite effects were explored: the effect of multiple positive charges necessary for membrane disintegration was equilibrated by the anchoring role of tryptophanes. Indeed, a series of Trp-terminated dendrimers exhibited high potency against clinical isolates of antibiotic resistant ESBL E. coli strains, stability in human plasma along with very low hemo- and genotoxicity. Investigation of the underlying antimicrobial mechanism indicated that the dendrimers studied at minimal inhibitory concentration showed weak permeability toward membranes. Solid-state 2D NMR studies revealed their presence on and inside the model membranes. Therefore, their biological properties might be explained by targeting of extra- or intracellular receptors. Our results point to a new approach to design novel branched antimicrobials with high therapeutic index.

Novel dendrimeric lipopeptides with antifungal activity

A series of new cationic lipopeptides containing branched, amphiphilic polar head derived from (Lys)Lys(Lys) dendron and C(8) or C(12) chain at C-end were designed, synthesized and characterized. Antimicrobial in vitro activity expressed as minimal inhibitory concentration (MIC) was evaluated against Gram-positive and Gram-negative bacteria and yeasts from the Candida genus. A significant enhancement of antimicrobial potency along with increased selectivity against Candida reference strains was detected for derivatives with the C(12) residue. Several compounds were characterized by a low hemotoxicity. The antifungal activity of branched lipopeptides is multimodal and concentration dependent. Several compounds, studied in detail, induced potassium leakage from fungal cells, caused morphological alterations of fungal cells and inhibited activity of candidal β(1,3)-glucan synthase.