PERIOCULAR HIGH RISK BCCS AFTER ADDITIONAL/PARALLEL INTAKE OF TORASEMIDE, MOXONIDINE AND MIRABEGRON: IMPORTANT LINKS TO SKIN CANCER RELATED (PHOTO-) NITROSOGENESIS IN THE CONTEXT OF PHARMACO-ONCOGENESIS

The Nitrosogenesis of skin cancer is a modern newly introduced concept in medicine, mainly concerning melanoma, but also keratinocytic cancers such as basal cell carcinoma. The nitroso-contamination of more than 300 drugs worldwide and the permanent (relatively short-term) intake of mutagen-contaminated drugs could create serious prerequisites for the development of skin cancer. Retrospective but also prospective analyses following potentially contaminated polymedication with a heterogeneous type of nitrosamines in real patients are indicative of a causal connection rather than a sporadic association between 1) intake of a possibly nitrosamine-contaminated drug and 2) generation of keratinocytic skin cancer. The pathogenesis of high-risk periocular localized basal cell carcinomas was until recently shrouded in mystery as it was mainly and until now associated with 1) intake of phototoxic drugs and 2) intense exposure to UV radiation (without intake of drugs), 3) congenital or acquired immunodeficiencies, and 4) Goltz Gorlin syndrome or 5) Xeroderma pigmentosum. Nitrosamines/ NDSRIs within the framework of polycotaminated drug intake appear to be one reasonable additional explanation for the association between carcinogen intake and subsequent skin cancer development and progression, and a relatively short-term one at that. Recently published scientific data provide information on a new ability of some of the nitrosamines - namely that some of them are photocarcinogenic or genotoxic after activation with UVA radiation. We present 4 patients who developed high-risk periocular localized basal cell carcinomas of the skin after/within the intake of potentially nitrosamine-contaminated drugs. The presented data are confirmatory with respect to previously published scientific observations on the carcinogenic effects of valsartan, candesartan, bisoprolol, metoprolol, perindopril, lisinopril and amlodipine. The contribution of newly validated data concerning potential/actual carcinogenic/genotoxic activity in the article is also due to the following newly announced nitroso preparations: torasemide, moxonidine and mirabegron. The expansion of the ˝bases of the pyramid˝ determining the stability of drug related (Photo) Nitrosogenesis/ Carcinogenesis (in terms of skin cancer generation) is growing daily. Exogenously/drug-induced Nitrosogenesis and the subsequently triggered carcinogenesis are a completely new explanatory concepts concerning the pathogenesis of skin tumors that remained unanalyzed and hidden for decades. Until now. The official lack of 1) availability, and of 2) precise concentrations regarding nitrosamines in medicinal preparations, are some of the most unexplained acts of irresponsibility to end-users and remain for the moment without a definitive answer from either regulators and manufacturers respectively. Polycontamination of polymedication in polymorbid patients remains highly problematic, at least as a cofactor in the development and progression of keratinocytic cancers, and this in the short term. Recently published data but also data from the past are suggestive that nitrosamines in tobacco are pivotal in the development of acquired mutations in p53 and RAS oncogenes in humans and rodents. The same genes are also affected by mutations in keratinocytic cancer patients. The overlapping mutation patterns of UV radiation-induced mutations in target genes such as p53 and RAS with those caused by some nitrosamines is indicative of a synergism available in terms of gene toxicity or possibly photocarcinogenicity of the latter. What leads the scientific community to believe that the nitrosamines in drugs, similar in composition and carcinogenic potency, act differently, is unclear. The link between drug intake, nitrosamine contamination, generation of some acquired mutations and subsequent cancer development becomes more than obvious and logically conditioned. The thesis of the controlled spread of cancer sounds more than logical today because: whoever controls and regulates the spread of carcinogens/mutagens/nitrosamines is also able to control the occurrence and spread of skin cancer. The Pharmaco-oncogenesis of skin cancer is determined by exogenously mediated Nitrosogenesis or the permissive availability for certain nitrosamines in drugs worldwide.

EDUCATION FROM DERMATOLOGISTS: THE SIMULTANEOUSLY DEVELOPMENT OF 16 KERATINOCYTIC CANCERS AFTER USE OF METFORMIN IN COMBINATION WITH LOSARTAN/ HYDROCHLOROTHIAZIDE, METOPROLOL AND NIFEDIPINE- IMPORTANT LINKS TO DRUG RELATED (PHOTO)-NITROSO-CARCINOGENESIS AND ONCOPHARMACOGENESIS

Oncopharmacogenesis and Drug-Induced Skin cancer related Nitrosogenesis are newly introduced concepts in the medical literature that owe their genesis or presence to the carcinogens/ mutagens, also known as nitrosamines/NDSRIs, which are present in a heterogeneous class of drugs. The contribution to the origin of these 2 concepts is entirely due to 1) the functions and efficacy of FDA in terms of control and identification of these carcinogens, and 2) the establishment of clinicopathological correlations by the dermatologists, occurring during drug intake. According to recent FDA data, the concentration of NDMA in just one metformin tablet could be up to more than 5-fold increased. The intake of 3 to 6 tablets per day should result in a carcinogen intake that is 15 to 30 times elevated within the day and within the monomedication alone. It is these circumstances that paraphrase/ ˝betonate˝ concepts such as Onco-Pharmacogenesis and Drug-mediated Nitrosogenesis of skin cancer. Although not officially declared, these mutagens are present and have been in forced tolerance mode for the last 30-40 years. And after their intake, multiple cancers have been found to develop. The concomitant use of other nitrosamine-contaminated drugs such as losartan/hydrochlorothiazide, metoprolol and nefidipine should certainly not be surprising when it could also be associated with the development of exactly 16 keratinocytic tumours as in the case presented by us. Recent evidence in medical literature has linked the nitrosamine N-nitrosomorpholine (NMOR) with the direct development of its subsequent mutagenic action in rodents following irradiation with UVA. This fact leaves open the question of the potentially available photocarcinogenic action of the other nitrosamines in humans found in medicinal preparations. This is what necessitates a clarification of the concept of Photo-Nitroso-Carcinogenesis/ Oncogenesis in humans and its relationship to skin cancer. The overlap of the mutational patterns of some of the nitrosamine-induced mutations in target genes such as p53 and RAS oncogenes, with those of UV light-induced mutations - or practically the same ones mentioned above, suggest a possible significant role of the Drug-Induced Photo-Nitroso-Carcinogenesis of keratinocyte cancer in the context of Onco-Pharmacogenesis. Future analyses should focus on elucidating the photocarcinogenic effect of nitrosamines in drug preparations and differentiating Skin cancer Nitrosogenesis from ˝pure˝ Photo-Carcinogenesis and Nitroso-Photo-Carcinogenesis. The localization of the tumors in the area of the UV-exposed sites within the potential/actual contamination of the 4 preparations (simultaneously) in the described patient are indicative of a possible pathogenetic influence in the context of the already mentioned Nitroso-(Photo)carcinogenesis. Polycontamination of polymedication remains a so far unresolvable problem.

High-Throughput and Format-Agnostic Mispairing Assay for Multispecific Antibodies Using Intact Mass Spectrometry

Multispecific antibodies have gained significant importance in a broad indication space due to their ability to engage multiple epitopes simultaneously and to thereby overcome therapeutic barriers. With growing therapeutic potential, however, the molecular complexity increases, thus intensifying the demand for innovative protein engineering and analytical strategies. A major challenge for multispecific antibodies is the correct assembly of light and heavy chains. Engineering strategies exist to stabilize the correct pairing, but typically individual engineering campaigns are required to arrive at the anticipated format. Mass spectrometry has proven to be a versatile tool to identify mispaired species. However, due to manual data analysis procedures, mass spectrometry is limited to lower throughputs. To keep pace with increasing sample numbers, we developed a high-throughput-capable mispairing workflow based on intact mass spectrometry with automated data analysis, peak detection, and relative quantification using Genedata Expressionist. This workflow is capable of detecting mispaired species of ∼1000 multispecific antibodies in three weeks and thus is applicable to complex screening campaigns. As a proof of concept, the assay was applied to engineering a trispecific antibody. Strikingly, the new setup has not only proved successful in mispairing analysis but has also revealed its potential to automatically annotate other product-related impurities. Furthermore, we could confirm the assay to be format-agnostic, as shown by analyzing several different multispecific formats in one run. With these comprehensive capabilities, the new automated intact mass workflow can be applied as a universal tool to detect and annotate peaks in a format-agnostic approach and in high-throughput, thus enabling complex discovery campaigns.

Trace elements in commonly used medicinal plants from Varna region, Bulgaria

In this study, we assessed the concentrations of some trace and toxic elements (Cd, Pb, Zn, Cu, Ni, Cr, Fe, and Mn) in traditionally used wild medicinal plants: chamomile (Matricaria chamomilla), white yarrow (Achillea millefolium), linden (Tilia sp.), and elder (Sambucus nigra L.) collected from urban and rural region near Varna, Bulgaria. Concentrations of examined elements were determined by inductively coupled plasma-optical emission spectrometry (ICP-OES) after sample mineralization. The samples were digested with concentrated nitric acid in a microwave system. Mean element levels in medicinal herbs were established in decreasing order as follows: Fe > Mn > Zn ≈ Cu > Pb > Ni > Cr > Cd. The content of toxic elements in medicinal herbs was found significantly higher in areas with intensive traffic compared with a suburban area. Instead discrimination between metal content in rural and urban samples was confirmed by PCA. Concentrations of toxic elements Cd and Pb in all plant species from the rural region were found in the range from not detected to 0.08 and 0.796 ng/kg, respectively and were below the permissible limit of the WHO.

An end-to-end automated platform process for high-throughput engineering of next-generation multi-specific antibody therapeutics

Next-generation multi-specific antibody therapeutics (MSATs) are engineered to combine several functional activities into one molecule to provide higher efficacy compared to conventional, mono-specific antibody therapeutics. However, highly engineered MSATs frequently display poor yields and less favorable drug-like properties (DLPs), which can adversely affect their development. Systematic screening of a large panel of MSAT variants in very high throughput (HT) is thus critical to identify potent molecule candidates with good yield and DLPs early in the discovery process. Here we report on the establishment of a novel, format-agnostic platform process for the fast generation and multiparametric screening of tens of thousands of MSAT variants. To this end, we have introduced full automation across the entire value chain for MSAT engineering. Specifically, we have automated the in-silico design of very large MSAT panels such that it reflects precisely the wet-lab processes for MSAT DNA library generation. This includes mass saturation mutagenesis or bulk modular cloning technologies while, concomitantly, enabling library deconvolution approaches using HT Sanger DNA sequencing. These DNA workflows are tightly linked to fully automated downstream processes for compartmentalized mammalian cell transfection expression, and screening of multiple parameters. All sub-processes are seamlessly integrated with tailored workflow supporting bioinformatics. As described here, we used this platform to perform multifactor optimization of a next-generation bispecific, cross-over dual variable domain-Ig (CODV-Ig). Screening of more than 25,000 individual protein variants in mono- and bispecific format led to the identification of CODV-Ig variants with over 1,000-fold increased potency and significantly optimized production titers, demonstrating the power and versatility of the platform.

AB0162 OCULAR MANIFESTATIONS IN PATIENTS WITH RHEUMATOID ARTHRITIS

Background:

Rheumatoid arthritis (RA) is the most common systemic autoimmune disease and is associated with a number of extra-articular organ manifestations, including ocular complications.

Objectives:

The aim of this study is to evaluate the frequency and characteristics of ocular manifestation in patients with rheumatoid arthritis (RA).

Methods:

The study involved 87 patients with RA. All the study subjects underwent complete ophthalmological examination involving visual acuity assessment, examination of anterior and posterior eye segments, Schirmer’s test, diameter and mobility of pupils, as well as eyeball mobility assessment of intraocular pressure. Data regarding age, gender, disease duration, age at diagnosis, systemic corticosteroid use, blood pressure, ocular symptoms and detailed ophthalmic history were recorded. The presence of rheumatoid factor in serum was evaluated by standard test methods based on principle of agglutination. All patients were seropositive.

Results:

87 patients (26 male, 59 female, mean age 45,6 ± 13,1 years; mean disease duration 7,4 ± 6,2 years) with RA were enrolled in this study. 31 (35,63 %) of them had no ocular symptoms. Among the patients with ocular symptoms, 39 (69,64 %) complained of decreased vision, 33 (58,93 %) - of dry eye, 32 (57,14 %) - of burning, 29 (51,78 %) -photophobia, 28 (50 %) - of gritty sensation, 27 (48,21 %) - of itching, 18 (32,14 %) - of redness, 13 (23,21 %) - of ocular pain, 3 (5,36 %) - of floaters. Ophthalmological examination revealed higher incidence of the following abnormalities in the study group: myopic astigmatism - in 10 (5,74 %) eyes, vascular abnormalities within fundus - in 22 (12,64 %) eyes, increased intraocular pressure (> 21 mm Hg) - in 11 (6,32 %) eyes. Mean IOP values were 17,34 ± 5,12 mm Hg. In 48 eyes Schirmer’s test results were below 10 mm, and in 18 eyes - below 5 mm. Keratoconjunctivitis sicca was present in 31 (35,63 %) of all patients. Episcleritis was diagnosed in 4 patients (4,6 %), scleritis – in 3 (3,45 %). Retinal vasculitis was present in 2 (2,3 %) patients and involves veins and arteries peripheral branches. Lens opacity was found in 13 (14,94 %) patients (21 eyes), mostly in the form of posterior subcapsular cataract (in 16 eyes) and nuclear cataract (in 5 eyes). The mean age of patients with cataracts was 52,3 ± 14,2 years. 13 of the patients with cataracts were either currently taking or had previously taken systemic corticosteroids.

Conclusion:

In patients with RA numerous abnormalities within the vision of organ may be found. Ocular symptoms are relatively common complications of RA, and may result in irreversible changes in the organ of vision. Regular ophthalmological examinations are essential among the patients with RA.

Disclosure of Interests:

None declared

FRI0253 OCULAR MANIFESTATIONS IN PATIENTS WITH SYSTEMIC SCLEROSIS

Background:

Systemic sclerosis (SSc) is a connective tissue disease with heterogeneous manifestations. It affects different organs and therefore requires interdisciplinary diagnostic and therapeutic management.

Objectives:

The aim of this study is to evaluate the frequency and characteristics of ocular manifestation in patients with systemic sclerosis.

Methods:

The study involved 31 patients with SSc. All the study subjects underwent complete ophthalmological examination involving visual acuity assessment, examination of anterior and posterior eye segments, Schirmer I test, diameter and mobility of pupils, as well as eyeball mobility assessment of intraocular pressure and ultrasound assessment of vitreous body. Data regarding age, gender, SSc subtype, disease duration, age at diagnosis, nailfold capillaroscopic pattern, systemic corticosteroid or chloroquine use, blood pressure, ocular symptoms and detailed ophthalmic history were recorded.

Results:

31 patients (3 male, 28 female, mean age 42,7 ± 14,3 years; mean disease duration 10,3±8,1 years) were enrolled in this study. 7 (22,58 %) of them had no ocular symptoms. Among the patients with ocular symptoms, 20 (64.52%) complained of decreased vision, 13 (41,93 %) - of itching, 14 (45,16%) - of burning, 8 (25,81%) - of eye fatigue,4 (12,90 %) - of ocular pain, 4 (12,90%) - of foreign body sensation, 16 (51,61 %) - of dry eye, 5 (52,03 %) -photophobia, 2 (6,45 %) - of floaters, 10 (32,26 %) - of redness. Hardening and thickening of palpebral skin was noted in 27 (87,10 %) patients. Ophthalmological examination revealed higher incidence of the following abnormalities in the study group: myopic astigmatism - in 20 (32,26 %) eyes, vascular abnormalities within fundus - in 24 (38,71%) eyes, increased intraocular pressure (> 21 mm Hg) - in 13 (20,97%) eyes. Mean IOP values were 18,21 ±4,2 mm Hg.Eyelid telangiectasias was noted in 9 (29,03 %) patients, chronic blepharitis - in 13(41,94 %). Lens opacity was found in 16 (51,61 %) patients (27 eyes), mostly in the form of posterior subcapsular cataract (in 20 eyes), nuclear cataract (in 6 eyes) and cortical cataract appearing as focal cystic opacities (in 1 eye). The mean age of patients with cataracts was 49,2 ± 12,3 years (11,4 years older than patients without cataracts). Additionally, 14 of the patients with cataracts were either currently taking or had previously taken systemic corticosteroids. Superficial conjunctival hyperaemia was noted in 20 (64,52 %), and varicose dilatation of subconjunctival and episcleral blood vessels in 9 (29,03 %) and 7 (22,58 %) patients, respectively. In 9 eyes (14,52 %) foci of pigment epithelium were found peripherally on the optic disc, In 6 (9,68 %) eyes - thinning of choroidal capillaries and retinal pigment epithelium, in 8 (12,90 %) - ischemic areas surrounded by microaneurysms and intraretinal extravasation, dilatation of the vessel-free fovea. сonjunctival fibrosis - in 8 (25,81 %) patients. In 25 eyes Schirmer I test results were below 10 mm, and in 7 eyes - below 5 mm. Eyelid stiffness was associated with difficulty in lid eversion and a woody texture upon palpation. Comparing patients with and without eyelid stiffness, we found that the mean age and the age at diagnosis were significantly lower in the former group (p < 0.01 and p < 0.05, respectively). The diffuse subtype was more prevalent among pts with eyelid skin changes (p < 0,05).

Conclusion:

In patients with SSc numerous abnormalities within the vision of organ may be found. Ocular symptoms are relatively common complications of SSc, and may result in serious, irreversible changes in the organ of vision. Regular ophthalmological examinations are essential among the patients with SSc.

Disclosure of Interests:

None declared

Redundancy in two major compound databases

Public repositories of compounds and activity data are of prime importance for pharmaceutical research in academic and industrial settings. Major databases have evolved over the years. Their growth is accompanied by an increasing tendency toward data sharing. This is a positive development but not without potential problems. Using ChEMBL and PubChem as examples, we show that crosstalk between databases also leads to substantial data redundancy that might not be obvious. Redundancy is an important issue because it biases data analysis and knowledge extraction and leads to inflated views of available compounds, assays and activity data. Going forward it will be important to further refine data exchange and deposition criteria and make redundancy as transparent as possible.

Mapping Biological Activities to Different Types of Molecular Scaffolds: Exemplary Application to Protein Kinase Inhibitors

Scaffolds were originally introduced to delineate core structures of active compounds. They are also used to assess the ability of computational methods to identify structurally diverse active compounds. Biological activities of compound series are often mapped to scaffolds. This is done to better understand activity distributions over different structural classes or search for core structures of compounds that are preferentially active against target families of interest. Herein, we describe in detail how such scaffold activity profiles are generated and compare profiles for differently defined scaffolds. As an exemplary application, scaffolds of currently available kinase inhibitors covering the human kinome are analyzed.

Exploring Structural Relationships between Bioactive and Commercial Chemical Space and Developing Target Hypotheses for Compound Acquisition

Analog series were systematically extracted from more than 650 000 bioactive compounds originating from medicinal chemistry and screening sources and more than 3.6 million commercial compounds that were not biologically annotated. Then, analog series-based (ASB) scaffolds were generated. For each scaffold from a bioactive series, a target profile was derived and ASB scaffolds shared by bioactive and commercial compounds were determined. On the basis of our analysis, large segments of commercial chemical space were not yet explored biologically. Shared ASB scaffolds established structural relationships between bioactive and commercial chemical space, and the target profiles of these scaffolds were transferred to commercially available analogs of active compounds. This made it possible to derive target hypotheses for more than 37 000 compounds without biological annotations covering more than 1000 different targets. For many molecules, alternative target assignments were available. Target hypotheses for these compounds should be of interest, for example, for hit expansion, acquisition of compounds to design or further extend focused libraries for drug discovery, or testing of expanded analog series on different targets. They can also be used to search for analogs and complement compound series during target-directed optimization. Therefore, all of the commercial molecules with new target hypotheses as well as key scaffolds identified in our analysis and their target profiles are made freely available.

Rationalizing Promiscuity Cliffs

Compound promiscuity can be viewed in different ways. We distinguish "bad" promiscuity resulting from chemical liabilities, nonspecific binding, or assay artifacts, from "good" promiscuity representing true multitarget activities. Investigating multitarget activities of small molecules is scientifically stimulating and therapeutically relevant. To better understand the molecular basis of multitarget activities, structure-promiscuity relationships (SPRs) are explored. For this purpose, "promiscuity cliffs" (PCs) have been introduced, which can be rationalized as an extension of the activity cliff (AC) concept. A PC is defined as a pair of structural analogues that are active against different numbers of targets (given a difference threshold). As discussed herein PCs frequently capture surprising SPRs and encode many experimentally testable hypotheses.

Assessing Scaffold Diversity of Kinase Inhibitors Using Alternative Scaffold Concepts and Estimating the Scaffold Hopping Potential for Different Kinases

Publicly available kinase inhibitors provide a large source of information for structure-activity relationship analysis and kinase drug design. In this study, publicly available inhibitors of the human kinome were collected and analog series formed by kinase inhibitors systematically identified. Then, alternative scaffold concepts were applied to assess diversity and promiscuity of kinase inhibitors. Over the past two years, the number of publicly available kinase inhibitors with high-confidence activity data more than doubled, but coverage of the human kinome only slightly increased. Approximately 70% of current kinase inhibitors belonged to analog series. However, the detectable degree of promiscuity among these kinase inhibitors remained low. Approximately 76% of all inhibitors were only annotated with a single kinase, compared to ~70% two years ago. For many kinases, the assessment of scaffold diversity among their inhibitors and the distribution of differently defined scaffolds over analog series made it possible to assess scaffold hopping potential. Our analysis revealed that the consideration of conventional compound-based scaffolds most likely leads to an overestimation of scaffold hopping frequency, at least for compounds forming analog series.

Application of a New Scaffold Concept for Computational Target Deconvolution of Chemical Cancer Cell Line Screens

Target deconvolution of phenotypic assays is a hot topic in chemical biology and drug discovery. The ultimate goal is the identification of targets for compounds that produce interesting phenotypic readouts. A variety of experimental and computational strategies have been devised to aid this process. A widely applied computational approach infers putative targets of new active molecules on the basis of their chemical similarity to compounds with activity against known targets. Herein, we introduce a molecular scaffold-based variant for similarity-based target deconvolution from chemical cancer cell line screens that were used as a model system for phenotypic assays. A new scaffold type was used for substructure-based similarity assessment, termed analog series-based (ASB) scaffold. Compared with conventional scaffolds and compound-based similarity calculations, target assignment centered on ASB scaffolds resulting from screening hits and bioactive reference compounds restricted the number of target hypotheses in a meaningful way and lead to a significant enrichment of known cancer targets among candidates.

Systematic analysis of structural and activity relationships between conventional hierarchical and analog series-based scaffolds

Three pairs of compounds (left) belonging to three different analog series that differ in their biological activity share a single conventional hierarchical scaffold (BM, middle) but have distinct ‘analog series-based’ (ASB) scaffold (right).

Identification and analysis of promiscuity cliffs formed by bioactive compounds and experimental implications

For three promiscuity cliffs (enclosed), cliff compounds, their promiscuity degrees (PDs), and color-coded substitution sites are shown. Comparison of these cliffs suggests the design of a new analog to further explore promiscuity.

Highly Promiscuous Small Molecules from Biological Screening Assays Include Many Pan-Assay Interference Compounds but Also Candidates for Polypharmacology

In PubChem screening assays, 466 highly promiscuous compounds were identified that were examined for known pan-assay interference compounds (PAINS) and aggregators using publicly available filters. These filters detected 210 PAINS and 67 aggregators. Compounds passing the filters included additional PAINS that were not detected, mostly due to tautomerism, and a variety of other potentially reactive compounds currently not encoded as PAINS. For a subset of compounds passing the filters, there was no evidence of potential artifacts. These compounds are considered candidates for further exploring multitarget activities and the molecular basis of polypharmacology.

Computational Method for the Systematic Identification of Analog Series and Key Compounds Representing Series and Their Biological Activity Profiles

A computational methodology is introduced for detecting all unique series of analogs in large compound data sets, regardless of chemical relationships between analogs. No prior knowledge of core structures or R-groups is required, which are automatically determined. The approach is based upon the generation of retrosynthetic matched molecular pairs and analog networks from which distinct series are isolated. The methodology was applied to systematically extract more than 17 000 distinct series from the ChEMBL database. For comparison, analog series were also isolated from screening compounds and drugs. Known biological activities were mapped to series from ChEMBL, and in more than 13 000 of these series, key compounds were identified that represented substitution sites of all analogs within a series and its complete activity profile. The analog series, key compounds, and activity profiles are made freely available as a resource for medicinal chemistry applications.

Advances in Activity Cliff Research

Activity cliffs, i.e. similar compounds with large potency differences, are of interest from a chemical and informatics viewpoint; as a source of structure-activity relationship information, for compound optimization, and activity prediction. Herein, recent highlights of activity cliff research are discussed including studies that have further extended our understanding of activity cliffs, yielded unprecedented insights, or paved the way for practical applications.

Systematic assessment of analog relationships between bioactive compounds and promiscuity of analog sets

Compound–analog relationships. Shown is an active compound with four substitution sites, two of which are explored with four and seven different R-groups, respectively.

Systematic design of analogs of active compounds covering more than 1000 targets

Analogs of active compounds. Shown is an active compound (top) with highlighted substitution sites at which a known (blue) and virtual (orange) analog have different R-groups.

Classification of matching molecular series on the basis of SAR phenotypes and structural relationships

Matching molecular series. Shown is a pair of structurally related matching molecular series that display different SAR characteristics.

Monitoring the Progression of Structure-Activity Relationship Information during Lead Optimization

Lead optimization (LO) in medicinal chemistry is largely driven by hypotheses and depends on the ingenuity, experience, and intuition of medicinal chemists, focusing on the key question of which compound should be made next. It is essentially impossible to predict whether an LO project might ultimately be successful, and it is also very difficult to estimate when a sufficient number of compounds has been evaluated to judge the odds of a project. Given the subjective nature of LO decisions and the inherent optimism of project teams, very few attempts have been made to systematically evaluate project progression. Herein, we introduce a computational framework to follow the evolution of structure-activity relationship (SAR) information over a time course. The approach is based on the use of SAR matrix data structures as a diagnostic tool and enables graphical analysis of SAR redundancy and project progression. This framework should help the process of making decisions in close-in analogue work.

Identification of orthologous target pairs with shared active compounds and comparison of organism-specific activity patterns

A systematic search for active small molecules shared by orthologous targets was carried out, leading to the identification of 803 compound-based orthologous target pairs covering a total of 938 orthologues, 358 unique targets and 98 organisms. Many orthologous target pairs were found to have substantial compound coverage, enabling the introduction of an orthologous target pairs classification including 'organism cliffs' and 'potency-retaining' pairs. A total of 158 orthologous target pairs involving human orthologues were identified, which were typically associated with drug discovery-relevant targets, organism combinations and compound data. Orthologous target pairs with human orthologues included 83 potency-retaining orthologous target pairs covering a variety of targets and organisms. On the basis of these orthologous target pairs, the compound search was further extended and 1149 potent compounds were identified that only had reported activities for non-human orthologues of 48 therapeutic targets, but not their human counterparts, hence providing a large pool of candidate compounds for further evaluation. The complete set of orthologous target pairs identified in our analysis, the orthologous target pairs classification including associated data and all candidate compounds are made freely available.

Target-based analysis of ionization states of bioactive compounds

Ionization states within a chemical neighborhood. Shown are an acidic and a basic analog of a neutral compound.

Advancing the activity cliff concept, part II

We present a follow up contribution to further complement a previous commentary on the activity cliff concept and recent advances in activity cliff research. Activity cliffs have originally been defined as pairs of structurally similar compounds that display a large difference in potency against a given target. For medicinal chemistry, activity cliffs are of high interest because structure-activity relationship (SAR) determinants can often be deduced from them. Herein, we present up-to-date results of systematic analyses of the ligand efficiency and lipophilic efficiency relationships between activity cliff-forming compounds, which further increase their attractiveness for the practice of medicinal chemistry. In addition, we summarize the results of a new analysis of coordinated activity cliffs and clusters they form. Taken together, these findings considerably add to our evaluation and current understanding of the activity cliff concept. The results should be viewed in light of the previous commentary article.

Recent progress in understanding activity cliffs and their utility in medicinal chemistry

The activity cliff concept is of high relevance for medicinal chemistry. Recent studies are discussed that have further refined our understanding of activity cliffs and suggested different ways of exploiting activity cliff information. These include alternative approaches to define and classify activity cliffs in two and three dimensions, data mining investigations to systematically detect all possible activity cliffs, the introduction of computational methods to predict activity cliffs, and studies designed to explore activity cliff progression in medicinal chemistry. The discussion of these studies is complemented with new findings revealing the frequency of activity cliff formation when different molecular representations are used and the distribution of activity cliffs across different targets. Taken together, the results have a number of implications for the practice of medicinal chemistry.

[HPV and spontaneous abortion: results from a virological study]

Human papillomavirus (HPV) infection is common among sexually active individuals and in some cases this infection could coincide with pregnancy in women. In this study, we present our results from investigation for HPV presence in the samples of 50 women with spontaneous abortions. Detection and typing of HPV were carried out by polymerase chain reaction (PCR), using the primers designed to amplify E6/E7 gene sequences of HPV-16, 18 and L1 gene region of HPV-6, 11. HPV DNA was found in 1.5% (3/50) of the clinical samples tested (HPV-16 in one patient, HPV-18--in another one and HPV-16 and HPV-18--in the third patient. Our results support the hypothesis that HPV might be associated with some cases of spontaneous abortions. However, a bigger number of cases are needed for further studies to assess the actual risk of this virus in pregnancy.