Whole exome sequencing to identify genetic markers for trastuzumab-induced cardiotoxicity

Genetic factors in the pathogenesis of cardio-oncology

In recent years, with advancements in medicine, the survival period of patients with tumours has significantly increased. The adverse effects of tumour treatment on patients, especially cardiac toxicity, have become increasingly prominent. In elderly patients with breast cancer, treatment-related cardiovascular toxicity has surpassed cancer itself as the leading cause of death. Moreover, in recent years, an increasing number of novel antitumour drugs, such as multitargeted agents, antibody‒drug conjugates (ADCs), and immunotherapies, have been applied in clinical practice. The cardiotoxicity induced by these drugs has become more pronounced, leading to a complex and diverse mechanism of cardiac damage. The risks of unintended cardiovascular toxicity are increased by high-dose anthracyclines, immunotherapies, and concurrent radiation, in addition to traditional cardiovascular risk factors such as smoking, hypertension, diabetes, hyperlipidaemia, and obesity. However, these factors do not fully explain why only a subset of individuals experience treatment-related cardiac toxicity, whereas others with similar clinical features do not. Recent studies indicate that genetics play a significant role in susceptibility to the development of cardiovascular toxicity from cancer therapies. These genes are involved in drug metabolism, oxidative damage, cardiac dysfunction, and other processes. Moreover, emerging evidence suggests that epigenetics also plays a role in drug-induced cardiovascular toxicity. We conducted a review focusing on breast cancer as an example to help oncologists and cardiologists better understand the mechanisms and effects of genetic factors on cardiac toxicity. In this review, we specifically address the relationship between genetic alterations and cardiac toxicity, including chemotherapy-related genetic changes, targeted therapy-related genetic changes, and immune therapy-related genetic changes. We also discuss the role of epigenetic factors in cardiac toxicity. We hope that this review will improve the risk stratification of patients and enable therapeutic interventions that mitigate these unintended adverse consequences of life-saving cancer treatments.

Cardiovascular Biomarkers in Cardio-Oncology: Antineoplastic Drug Cardiotoxicity and Beyond

Serum biomarkers represent a reproducible, sensitive, minimally invasive and inexpensive method to explore possible adverse cardiovascular effects of antineoplastic treatments. They are useful tools in risk stratification, the early detection of cardiotoxicity and the follow-up and prognostic assessment of cancer patients. In this literature review, we aim at describing the current state of knowledge on the meaning and the usefulness of cardiovascular biomarkers in patients with cancer; analyzing the intricate relationship between cancer and cardiovascular disease (especially HF) and how this affects cardiovascular and tumor biomarkers; exploring the role of cardiovascular biomarkers in the risk stratification and in the identification of chemotherapy-induced cardiotoxicity; and providing a summary of the novel potential biomarkers in this clinical setting.

Multimodal Imaging of Cancer Therapy-Related Cardiac Dysfunction in Breast Cancer-A State-of-the-Art Review

BACKGROUND

This review focuses on multimodality imaging of cardiotoxicity in cancer patients, with the aim of evaluating the effectiveness of different techniques in detecting and monitoring cardiac changes associated with cancer therapy.

METHODS

Eight studies were included in the review, covering various imaging modalities such as cardiac magnetic resonance imaging, echocardiography, and multigated acquisition scanning.

RESULTS

Cardiac magnetic resonance imaging emerged as the most definitive modality, offering real-time detection, comprehensive assessment of cardiac function, the ability to detect early myocardial changes, and superior detection of cardiotoxicity when compared to the other imaging modalities. The studies also emphasize the importance of parameters such as left ventricular ejection fraction and global longitudinal strain in assessing cardiac function and predicting cardiotoxicity.

CONCLUSION

Due to the common use of HER2 agents and anthracyclines within the breast cancer population, the LVEF as a critical prognostic measurement for assessing heart health and estimating the severity of left-sided cardiac malfunction is a commonly used endpoint. CTRCD rates differed between imaging modalities, with cardiac MRI the most sensitive. The use of multimodal cardiac imaging remains a nuanced area, influenced by local availability, the clinical question at hand, body habits, and medical comorbidities. All of the imaging modalities listed have a role to play in current care; however, focus should be given to increasing the provision of cardiac MRI for breast cancer patients in the future to optimize the detection of CTRCD and patient outcomes thereafter.

Biomarkers of Trastuzumab-Induced Cardiac Toxicity in HER2- Positive Breast Cancer Patient Population

Simple Summary

Trastuzumab administered as a (neo)adjuvant therapy in radically treated Human Epidermal Growth Factor Receptor 2 (HER2)-positive breast cancer patients improves overall survival. This study aimed to assess if factors commonly thought to play a role as biomarkers of trastuzumab-induced cardiotoxicity (TIC) are pathognomonic for this injury. Data obtained for 130 HER2-positive breast cancer patients do not support an influence of N-terminal brain natriuretic peptide (NT-proBNP), creatine kinase-MB (CK-MB), or myoglobin on the frequency of TIC. Suggestions for trastuzumab therapy include: close cooperation between cardiologists and oncologists; not using NT-proBNP, CK-MB, or myoglobin as standard TIC predictive markers; organizing prospective studies assessing the role of these parameters as TIC predictive markers in the case of HER2 blockage in conjunction with doublet immunotherapy or other anti-HER2 agents.

Abstract

Trastuzumab-induced cardiotoxicity (TIC) can lead to early treatment discontinuation. The aim of this study was to evaluate: N-terminal brain natriuretic peptide (NT-proBNP), creatine kinase-MB (CK-MB), myoglobin, and selected biochemical and clinical factors as predictors of TIC. One hundred and thirty patients with HER2-positive BC receiving adjuvant trastuzumab therapy (TT) were enrolled. Measurement of cardiac markers and biochemical tests as well as echocardiography were performed prior to TT initiation and every three months thereafter. Cardiotoxicity leading to treatment interruption occurred in 24 patients (18.5%). While cardiotoxicity caused early treatment discontinuation in 14 patients (10.8%), the TIC resolved in 10 (7.7%) and TT was resumed. The most common complication was a decrease in left ventricular ejection fraction of more than 10% from baseline or below 50% (7.7%). In patients with TIC, there was no increase in the levels of NT-proBNP, myoglobin, and CK-MB. BMI, hypertension, ischemic heart disease, diabetes, age, cancer stage, type of surgery, use of radiotherapy, chemotherapy, and hormone therapy were shown to not have an effect on TIC occurrence. NT-proBNP, myoglobin, and CK-MB are not predictors of TIC. There is an ongoing need to identify biomarkers for TIC.

Genetic and RNA-related molecular markers of trastuzumab-chemotherapy-associated cardiotoxicity in HER2 positive breast cancer: a systematic review

Cancer-therapy related cardiotoxicity (CTRCT) is a significant and frequent complication of monoclonal antibody directed therapy, especially Trastuzumab, for human epidermal growth factor receptor 2 (HER2) overexpressing breast cancers. Reliable, clinically available molecular predictive markers of CTRCT have not yet been developed. Identifying specific genetic variants and their molecular markers, which make the host susceptible to this complication is key to personalised risk stratification. A systematic review was conducted until April 2021, using the Medline, Embase databases and Google Scholar, to identify studies genetic and RNA-related markers associated with CTRCT in HER2 positive breast cancer patients. So far, researchers have mainly focused on HER2 related polymorphisms, revealing codons 655 and 1170 variants as the most likely SNPs associated with cardiotoxicity, despite some contradictory results. More recently, new potential genetic markers unrelated to the HER2 gene, and linked to known cardiomyopathy genes or to genes regulating cardiomyocytes apoptosis and metabolism, have been detected. Moreover, microRNAs are gaining increasing recognition as additional potential molecular markers in the cardio-oncology field, supported by encouraging preliminary data about their relationship with cardiotoxicity in breast cancers. In this review, we sought to synthesize evidence for genetic variants and RNA-related molecular markers associated with cardiotoxicity in HER2-positive breast cancer.

Evaluation of photoreceptor-directed fibroblasts derived from retinitis pigmentosa patients with defects in the EYS gene: a possible cost-effective cellular model for mechanism-oriented drug

Background

The most common gene responsible for autosomal recessive retinitis pigmentosa (RP) is EYS. The manner of decay of genetically defective EYS gene transcripts varies depending on the type of mutation using our cellular model, which consists of induced photoreceptor-directed fibroblasts from EYS-RP patients (EYS-RP cells). However, disease-specific profiles have not been clarified in EYS-RP cells. Herein we investigated comprehensive gene expression patterns and restoration of altered expression by low molecular weight molecules in EYS-RP cells.

Methods

Using induced photoreceptor-like cells by CRX, RAX, NeuroD, and OTX2, we employed qRT-PCR and DNA microarray analysis to compare expression levels of disease-related genes in EYS-RP cells. We investigated the effect of antiapoptotic or anti-endoplasmic reticulum (ER) stress/antioxidant reagents on the restoration of altered gene expression.

Results

Expression levels of phototransduction-related genes (blue opsin, rhodopsin, S-antigen, GNAT1, GNAT2) were lower in EYS-RP cells. CRYGD was extracted by global gene expression analysis, as a downregulated, retina-related and apoptosis-, endoplasmic reticulum (ER) stress- or aging-related gene. Pathway enrichment analysis suggested that “complement and coagulation cascades,” “ECM-receptor interaction” and “PI3K-Akt signaling pathway” could be involved in EYS-RP-associated pathogenesis. Among the matching/overlapping genes involved in those pathways, F2R was suggested as an EYS-RP-associated gene. The downregulation of CRYGD and F2R was completely restored by additional 4-PBA, an inhibitor of ER stress, and partially restored by metformin or NAC. In addition, 4-PBA normalized the expression level of cleaved caspase-3.

Conclusions

Our cellular model may reflect the ER stress-mediated degenerative retina and serve as a pathogenesis-oriented cost-effective rescue strategy for RP patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-02827-x.

Whole-exome Sequencing Reveals New Potential Susceptibility Genes for Japanese Familial Pancreatic Cancer

OBJECTIVE

The primary objective of this study was to identify novel genes that predispose people in the Japanese population to FPC.

SUMMARY OF BACKGROUND DATA

Familial history of pancreatic cancer is an important risk factor but, to date, few genes predisposing individuals to increased risk of developing FPC have been identified.

METHODS

We performed whole-exome sequencing of germline DNA from 81 Japanese FPC patients. We also investigated somatic gene alterations in 21 matched tumor tissues through whole-exome sequencing and copy number analysis.

RESULTS

Our germline variants identified previously known FPC susceptibility genes such as ATM and BRCA2, and several novel tumor suppressor genes with potentially deleterious variants for FPC. Interestingly, somatic whole-exome analysis demonstrated that most tumor samples with suspicious loss of heterozygosity of candidate genes were KRAS wild-types, implying that these cases may not have required KRAS activation as a driver event for carcinogenesis.

CONCLUSIONS

Our findings indicate that FPC patients harbor potentially deleterious causative germline variants in tumor suppressor genes, which are known to acquire somatic mutations in pancreatic cancer, and that somatic loss of heterozygosity of some FPC susceptibility genes may contribute to the development of FPC in the absence of somatic KRAS-activating mutation. Genetic testing for a wider variety of FPC-predisposition genes could provide better screening approach for high-risk groups of pancreatic cancer.

Transcriptomic Analysis of Breast Cancer Patients Sensitive and Resistant to Chemotherapy: Looking for Overall Survival and Drug Resistance Biomarkers

Worldwide breast cancer ranks first in mortality and incidence rates in women over 20 years old. Rather than one disease, breast cancer is a heterogeneous group of diseases that express distinct molecular profiles. Neoadjuvant chemotherapy is an important therapeutic strategy for breast cancer patients independently of their molecular subtype, with the drawback of resistance development. In addition, chemotherapy has adverse effects that combined with resistance could contribute to lower overall survival. Although great efforts have been made to find diagnostic and prognostic biomarkers for breast cancer and for response to targeted and immune therapy for this pathology, little has been explored regarding biomarkers of response to anthracyclines and taxanes based neoadjuvant chemotherapy. This work aimed to evaluate the molecular profile of patients who received neoadjuvant chemotherapy to identify differentially expressed genes (DEGs) that could be used as biomarkers of chemotherapy response and overall survival. Breast cancer patients who were candidates for neoadjuvant chemotherapy were enrolled in this study. After treatment and according to their pathological response, they were assigned as sensitive or resistant. To evaluate DEGs, Gene Ontology, Kyoto Encyclopedia Gene and Genome (KEGG), and protein–protein interactions, RNA-seq information from all patients was obtained by next-generation sequencing. A total of 1985 DEGs were found, and KEGG analysis indicated a great number of DEGs in metabolic pathways, pathways in cancer, cytokine–cytokine receptor interactions, and neuroactive ligand-receptor interactions. A selection of 73 DEGs was used further for an analysis of overall survival using the METABRIC study and the ductal carcinoma dataset of The Cancer Genome Atlas (TCGA) database. Nine DEGs correlated with overall survival, of which the subexpression of C1QTNF3, CTF1, OLFML3, PLA2R1, PODN, KRT15, HLA-A, and the overexpression of TUBB and TCP1 were found in resistant patients and related to patients with lower overall survival.

Whole-exome sequencing reveals novel candidate single nucleotide variations for preventing adverse effects of levonorgestrel implantation

Aim: To identify novel genes associated with adverse effects of levonorgestrel (LNG) implants based on comparative whole-exome sequencing. Materials & methods: A cohort comprising 104 participants, including 52 controls and 52 women with LNG-related adverse effects, was recruited. Seven cases and eight controls were selected for whole-exome sequencing. We verified 13 single nucleotide variations (SNVs) related with integrin-mediated signaling pathway and cell proliferation using the MassARRAY platform. Results: Finally, we screened 49 cases and 52 controls for analyses. Two SNVs (rs7255721 and rs1042522) were located in ADAMTS10 and TP53, respectively, and significantly different between two groups. These two SNVs lead to changes in protein structure and physicochemical parameters. Conclusion: Here, we defined two pathogenic mutations related to adverse LNG effects.

Dissecting the role of EYS in retinal degeneration: clinical and molecular aspects and its implications for future therapy

Mutations in the EYS gene are one of the major causes of autosomal recessive retinitis pigmentosa. EYS-retinopathy presents a severe clinical phenotype, and patients currently have no therapeutic options. The progress in personalised medicine and gene and cell therapies hold promise for treating this degenerative disease. However, lack of understanding and incomplete comprehension of disease's mechanism and the role of EYS in the healthy retina are critical limitations for the translation of current technical advances into real therapeutic possibilities. This review recapitulates the present knowledge about EYS-retinopathies, their clinical presentations and proposed genotype–phenotype correlations. Molecular details of the gene and the protein, mainly based on animal model data, are analysed. The proposed cellular localisation and roles of this large multi-domain protein are detailed. Future therapeutic approaches for EYS-retinopathies are discussed.

Cardiotoxicity in HER2-positive breast cancer patients

Due to the recent advances in diagnosis and management of patients with HER2-positive breast cancer, especially through novel HER2-targeted agents, cardiotoxicity becomes an emerging problem. Although chemotherapy significantly increases survival, the risk of cardiovascular disease development is high and still underestimated and could imply treatment discontinuation. Frequently, due to lack of rigorous diagnosis strategies, cardiotoxicity assessment is delayed, and, moreover, the efficacy of current therapy options in restoring heart function is questionable. For a comprehensive risk assessment, it is vital to characterize the clinical spectrum of HER2-targeted agents and anthracyclines, as well as their pathogenic pathways involved in cardiotoxicity. Advanced cardiovascular multimodal imaging and circulating biomarkers plays primary roles in early assessing cardiotoxicity and also in guiding specific preventive measures. Even though the knowledge in this field is rapidly expanding, there are still questions that arise regarding the optimal approach in terms of timing and methods. The aim of the current review aims to providean overview of currently available data.

Liquid biopsy as a perioperative biomarker of digestive tract cancers: review of the literature

Tissue biopsies are the gold-standard for investigating the molecular characterization of tumors. However, a "solid" biopsy is an invasive procedure that cannot capture real-time tumor dynamics and may yield inaccurate information because of intratumoral heterogeneity. In this review, we summarize the current state of knowledge about surgical treatment-associated "liquid" biopsy for patients with digestive organ tumors. A liquid biopsy is a technique involving the sampling and testing of non-solid biological materials, including blood, urine, saliva, and ascites. Previous studies have reported the potential value of blood-based biomarkers, circulating tumor cells, and cell-free nucleic acids as facilitators of cancer treatment. The applications of a liquid biopsy in a cancer treatment setting include screening and early diagnosis, prognostication, and outcome and recurrence monitoring of cancer. This technique has also been suggested as a useful tool in personalized medicine. The transition to precision medicine is still in its early stages. Soon, however, liquid biopsy is likely to form the basis of patient selection for molecular targeted therapies, predictions regarding chemotherapy sensitivity, and real-time evaluations of therapeutic effects.

Pharmacogenetics for severe adverse drug reactions induced by molecular-targeted therapy

Molecular-targeted drugs specifically interfere with molecules that are frequently overexpressed or mutated in cancer cells. As such, these drugs are generally considered to precisely attack cancer cells, thereby inducing fewer adverse drug reactions (ADRs). However, molecular-targeted drugs can still cause characteristic ADRs that, although rarely severe, can be life-threatening. Therefore, it is becoming increasingly important to be able to predict which patients are at risk of developing ADRs after treatment with molecular-targeted therapy. The emerging field of pharmacogenetics aims to better distinguish the genetic variants associated with drug toxicity and efficacy to improve the selection of therapeutic strategies for each genetic profile. Here, we provide an overview of the current reports on the relationship between genetic variants and molecular-targeted drug-induced severe ADRs in oncology.

Human In Vitro Models for Assessing the Genomic Basis of Chemotherapy-Induced Cardiovascular Toxicity

Chemotherapy-induced cardiovascular toxicity (CICT) is a well-established risk for cancer survivors and causes diseases such as heart failure, arrhythmia, vascular dysfunction, and atherosclerosis. As our knowledge of the precise cardiovascular risks of each chemotherapy agent has improved, it has become clear that genomics is one of the most influential predictors of which patients will experience cardiovascular toxicity. Most recently, GWAS-led, top-down approaches have identified novel genetic variants and their related genes that are statistically related to CICT. Importantly, the advent of human-induced pluripotent stem cell (hiPSC) models provides a system to experimentally test the effect of these genomic findings in vitro, query the underlying mechanisms, and develop novel strategies to mitigate the cardiovascular toxicity liabilities due to these mechanisms. Here we review the cardiovascular toxicities of chemotherapy drugs, discuss how these can be modeled in vitro, and suggest how these models can be used to validate genetic variants that predispose patients to these effects.

The pan-cancer landscape of prognostic germline variants in 10,582 patients

Background

While clinical factors such as age, grade, stage, and histological subtype provide physicians with information about patient prognosis, genomic data can further improve these predictions. Previous studies have shown that germline variants in known cancer driver genes are predictive of patient outcome, but no study has systematically analyzed multiple cancers in an unbiased way to identify genetic loci that can improve patient outcome predictions made using clinical factors.

Methods

We analyzed sequencing data from the over 10,000 cancer patients available through The Cancer Genome Atlas to identify germline variants associated with patient outcome using multivariate Cox regression models.

Results

We identified 79 prognostic germline variants in individual cancers and 112 prognostic germline variants in groups of cancers. The germline variants identified in individual cancers provide additional predictive power about patient outcomes beyond clinical information currently in use and may therefore augment clinical decisions based on expected tumor aggressiveness. Molecularly, at least 12 of the germline variants are likely associated with patient outcome through perturbation of protein structure and at least five through association with gene expression differences. Almost half of these germline variants are in previously reported tumor suppressors, oncogenes or cancer driver genes with the other half pointing to genomic loci that should be further investigated for their roles in cancers.

Conclusions

Germline variants are predictive of outcome in cancer patients and specific germline variants can improve patient outcome predictions beyond predictions made using clinical factors alone. The germline variants also implicate new means by which known oncogenes, tumor suppressor genes, and driver genes are perturbed in cancer and suggest roles in cancer for other genes that have not been extensively studied in oncology. Further studies in other cancer cohorts are necessary to confirm that germline variation is associated with outcome in cancer patients as this is a proof-of-principle study.

Electronic supplementary material

The online version of this article (10.1186/s13073-020-0718-7) contains supplementary material, which is available to authorized users.

Whole genome sequencing to identify predictive markers for the risk of drug-induced interstitial lung disease

Drug-induced interstitial lung disease (DIILD) is a serious side effect of chemotherapy in cancer patients with an extremely high mortality rate. In this study, to identify genetic variants with greater risk of DIILD, we carried out whole genome sequencing (WGS) of germline DNA samples from 26 patients who developed DIILD, and conducted a case-control association study between these 26 cases and general Japanese population controls registered in the integrative Japanese Genome Variation Database (iJGVD) as a screening study. The associations of 42 single nucleotide variants (SNVs) showing P < 0.0001 were further validated using an independent cohort of 18 DIILD cases as a replication study. A further combined analysis of the screening and replication studies showed a possible association of two SNVs, rs35198919 in intron 1 of the chromosome 22 open reading frame 34 (C22orf34) and rs12625311 in intron 1 of the teashirt zinc finger homeobox 2 (TSHZ2), with DIILD (P_combined = 1.87 × 10⁻⁵ and 5.16 × 10⁻⁵, respectively). Furthermore, in a subgroup analysis of epidermal growth factor receptor (EGFR)–tyrosine kinase inhibitor (TKI)-induced interstitial lung disease (ILD), we observed seven candidate SNVs that were possibly associated with ILD (P < 0.00001). This is the first study to identify genetic markers for the risk of DIILD using WGS. Collectively, our novel findings indicate that these SNVs may be applicable for predicting the risk of DIILD in patients receiving chemotherapy.

Antineoplastic-related cardiovascular toxicity: A systematic review and meta-analysis in Asia

BACKGROUND

Cancer and heart diseases are the leading causes of morbidity and mortality in many countries worldwide. Recent advancement in chemotherapy and targeted therapies has led to an improvement in cancer survival rates, but at a cost of higher cardiac side effects. However, report on antineoplastic-related cardiotoxicities incidence in Asia is lacking.

METHODS

We systematically searched multiple databases to identify studies reporting incidence of antineoplastic-related cardiovascular toxicity in Asia published from inception to November 2018. Pre-specified subgroups were performed to explore heterogeneity and study quality assessed and reported according to PRISMA guidelines.

RESULTS

A total of 61 studies across 11 countries in Asia reported 8 types of cardiovascular toxicities were included. These studies mostly reported on adult populations, and usually examined cardiotoxicities related to anthracycline use. The most frequently reported cardiotoxicities were heart failure, electrocardiogram abnormalities and left ventricular dysfunction. The pooled estimated incidence of cardiotoxicity was 4.27% (95% CI: 3.53-5.07). Subgroup analysis showed higher incidence in middle income countries compared to high income countries.

CONCLUSIONS

Although robust incidence studies are sparse, cardiovascular complications affects approximately one in twenty cancer patients in Asia. This highlights a unique opportunity of cancer patients caring that need cardiologists and oncologist to become familiar with this emerging sub-specialty.

Intra- and interspecies comparison of EYS transcripts highlights its characteristics in the eye

Inherited mutations in the eyes shut homolog (EYS) gene cause retinitis pigmentosa. Although knock out of eys in zebrafish is pathogenic, the molecular function of EYS in vertebrate photoreceptors is poorly understood. Here, we show that the 5' portion of EYS is eye-specific across vertebrates. We previously determined that a 3' fragment of EYS with an unknown transcription start site is expressed in human dermal fibroblasts (HDF). To obtain insights into the molecular function of EYS in vertebrate photoreceptors, we extensively analyzed EYS (eys) expression in the human fibroblast cell line HDF-adult (HDF-a), the Y79 retinoblastoma cell line, and in zebrafish eyes using rapid amplification of cDNA end, cap analysis of gene expression, RNA sequencing, and RT-PCR. In HDF-a cells, we identified a novel transcript variant (tv), tv5, transcribed from exon 37. In Y79 cells and zebrafish eyes, EYS (eys) was predominantly transcribed from exon 1 or 2, whereas it was transcribed exclusively from exon 37 in HDF-a cells. In the zebrafish eye, there were splice variants that introduced stop codons, resulting in complete loss of the 3' portion of the RNA. These comparative approaches indicate that the 5' portion of the EYS (eys) mRNA appears to be photoreceptor-specific and that the compositions of the deduced EYS proteins in the eye are well-conserved across vertebrates.-Takita, S., Miyamoto-Matsui, K., Seko, Y. Intra- and interspecies comparison of EYS transcripts highlights its characteristics in the eye.

hiPSCs in cardio-oncology: deciphering the genomics

The genomic predisposition to oncology-drug-induced cardiovascular toxicity has been postulated for many decades. Only recently has it become possible to experimentally validate this hypothesis via the use of patient-specific human-induced pluripotent stem cells (hiPSCs) and suitably powered genome-wide association studies (GWAS). Identifying the individual single nucleotide polymorphisms (SNPs) responsible for the susceptibility to toxicity from a specific drug is a daunting task as this precludes the use of one of the most powerful tools in genomics: comparing phenotypes to close relatives, as these are highly unlikely to have been treated with the same drug. Great strides have been made through the use of candidate gene association studies (CGAS) and increasingly large GWAS studies, as well as in vivo whole-organism studies to further our mechanistic understanding of this toxicity. The hiPSC model is a powerful technology to build on this work and identify and validate causal variants in mechanistic pathways through directed genomic editing such as CRISPR. The causative variants identified through these studies can then be implemented clinically to identify those likely to experience cardiovascular toxicity and guide treatment options. Additionally, targets identified through hiPSC studies can inform future drug development. Through careful phenotypic characterization, identification of genomic variants that contribute to gene function and expression, and genomic editing to verify mechanistic pathways, hiPSC technology is a critical tool for drug discovery and the realization of precision medicine in cardio-oncology.

Roles of pharmacogenomics in non-anthracycline antineoplastic-induced cardiovascular toxicities: A systematic review and meta-analysis of genotypes effect

BACKGROUND

Exploration on genetic roles in antineoplastic-related cardiovascular toxicity has increased with the advancement of genotyping technology. However, knowledge on the extent of genetic determinants in affecting the susceptibility to the cardiovascular toxicities of antineoplastic is limited. This study aims to identify potential single nucleotide polymorphism (SNP) in predicting non-anthracycline antineoplastic-related cardiovascular toxicity.

METHODS

We systematically searched for original research in PubMed, Cochrane Central Register of Controlled Studies, CINAHL Plus, EMBASE and HuGE Navigator from database inception until January 2018. Studies on association between polymorphism and antineoplastic-induced cardiovascular toxicity in patients treated for cancer of all antineoplastic agents were included except for anthracycline. Case reports, conference abstracts, reviews and non-patient studies were excluded. Data extracted by two independent reviewers were combined with random-effects model and reported according to PRISMA and MOOSE guidelines.

RESULTS

The 35 studies included examined a total of 219 SNPs in 80 genes, 11 antineoplastic and 5 types of cardiovascular toxicities. Meta-analyses showed that human epidermal growth factor receptor 2 (HER2) rs1136201, a risk variants (pooled OR: 2.43; 1.17-5.06, p = 0.018) is a potential predictors for trastuzumab-related cardiotoxicity. Gene dose effect analysis showed number of variant allele may contribute to the risk too.

CONCLUSIONS

This review found that HER2 rs1136201 can have the potential in predicting trastuzumab-related heart failure. As such, further studies are needed to confirm the validity of these results as well as determine the economic aspect of using SNPs prior to its implementation as a clinical practice.

Whole exome sequencing to identify genetic markers for trastuzumab-induced cardiotoxicity

Although trastuzumab‐induced cardiotoxicity is an important determinant to limit the use of this drug, the molecular mechanism of risk for this toxicity is not well understood. To identify genetic variants determining the risk of trastuzumab‐induced cardiotoxicity, we carried out whole exome sequencing of germline DNA samples from 9 patients with trastuzumab‐induced cardiotoxicity, and conducted a case‐control association study of 2258 genetic variants between 9 cases (with trastuzumab‐induced cardiotoxicity) and general Japanese population controls registered in the Human Genetic Variation Database (HGVD). The top variant which showed the lowest P‐value in the screening study was rs139503277 in PHD Finger Protein 3 (P_min = .00012, odds ratio [OR] = 51.23). To further validate the result of screening study, we carried out a replication study of 10 variants showing P_min < .001 in the screening study using 234 independent patients treated with trastuzumab, including 10 cases and 224 controls (without trastuzumab‐induced cardiotoxicity). In the replication study, we observed that three variants had an effect in the same direction as in the screening study (rs78272919 in exon 2 of Keratin 15, rs5762940 in exon 2 of zinc and ring finger 3, and rs139944387 in exon 44 of Eyes shut homologs [EYS]). A combined result of the screening and the replication studies suggested an association of a locus on chromosome 6q12 with trastuzumab‐induced cardiotoxicity (rs139944387 in EYS, combined P_min = .00056, OR = 13.73). This finding provides new insights into personalized trastuzumab therapy for patients with human epidermal growth factor receptor 2 (HER2)‐positive cancer.