The First Case of Severe Takotsubo Cardiomyopathy Associated with 5-Fluorouracil in a Patient with Abnormalities of Both Dihydropyrimidine Dehydrogenase (DPYD) and Thymidylate Synthase (TYMS) Genes

Cardiotoxicity of anti-cancer drugs: cellular mechanisms and clinical implications

Cardio-oncology is an emerging field that seeks to enhance quality of life and longevity of cancer survivors. It is pertinent for clinicians to understand the cellular mechanisms of prescribed therapies, as this contributes to robust understanding of complex treatments and off-target effects, improved communication with patients, and guides long term care with the goal to minimise or prevent cardiovascular complications. Our aim is to review the cellular mechanisms of cardiotoxicity involved in commonly used anti-cancer treatments and identify gaps in literature and strategies to mitigate cardiotoxicity effects and guide future research endeavours.

Fluoropyrimidine Cardiotoxicity: Incidence, Outcomes, and Safety of Rechallenge

PURPOSE OF REVIEW

Fluoropyrimidine (FDP) chemotherapy regimens used in the treatment of solid tumors such as breast, gastrointestinal, and hepatobiliary malignancies have led to significant survival benefits. However, FDP cardiotoxicity can lead to premature termination of FDP-based chemotherapy treatments. Resuming these crucial therapies after initial FDP cardiotoxicity can be challenging for patients and healthcare providers.

RECENT FINDINGS

Symptomatic cardiotoxicity occurs in up to 35% of patients treated with FDP-based chemotherapy. The most common symptom is chest pain, but palpitations, dyspnea, myocardial infarction, cardiogenic shock, and cardiac arrest can also occur. Several large studies have attempted to discern clinical and genetic risk factors in those who develop FDP cardiotoxicity. With cardiac risk factor optimization and aggressive pre-treatment with anti-anginal agents, rechallenging with FDP is possible and allows patients to resume optimal cancer-directed treatment. FDP cardiotoxicity remains a poorly understood identity. We highlight several recent publications attempting to define the risk factors associated with developing FDP cardiotoxicity. The management of FDP cardiotoxicity and consideration of rechallenge of FDP-based regimens highlights the importance of a multidisciplinary partnership between oncologists and cardiologists/cardio-oncologists.

Characterization of ADME Gene Variation in Colombian Population by Exome Sequencing

In genes related to drug pharmacokinetics, molecular variations determine interindividual variability in the therapeutic efficacy and adverse drug reactions. The assessment of single-nucleotide variants (SNVs) is used with growing frequency in pharmacogenetic practice, and recently, high-throughput genomic analyses obtained through next-generation sequencing (NGS) have been recognized as powerful tools to identify common, rare and novel variants. These genetic profiles remain underexplored in Latin-American populations, including Colombia. In this study, we investigated the variability of 35 genes included in the ADME core panel (absorption, distribution, metabolism, and excretion) by whole-exome sequencing (WES) of 509 unrelated Colombian individuals with no previous reports of adverse drug reactions. Rare variants were filtered according to the minor allele frequencies (MAF) <1% and potential deleterious consequences. The functional impact of novel and rare missense variants was assessed using an optimized framework for pharmacogenetic variants. Bioinformatic analyses included the identification of clinically validated variants described in PharmGKB and ClinVar databases. Ancestry from WES data was inferred using the R package EthSEQ v2.1.4. Allelic frequencies were compared to other populations reported in the public gnomAD database. Our analysis revealed that rare missense pharmacogenetic variants were 2.1 times more frequent than common variants with 121 variants predicted as potentially deleterious. Rare loss of function (LoF) variants were identified in 65.7% of evaluated genes. Regarding variants with clinical pharmacogenetic effect, our study revealed 89 sequence variations in 28 genes represented by missense (62%), synonymous (22.5%), splice site (11.2%), and indels (3.4%). In this group, ABCB1, ABCC2, CY2B6, CYP2D6, DPYD, NAT2, SLC22A1, and UGTB2B7, are the most polymorphic genes. NAT2, CYP2B6 and DPYD metabolizer phenotypes demonstrated the highest variability. Ancestry analysis indicated admixture in 73% of the population. Allelic frequencies exhibit significant differences with other Latin-American populations, highlighting the importance of pharmacogenomic studies in populations of different ethnicities. Altogether, our data revealed that rare variants are an important source of variability in pharmacogenes involved in the pharmacokinetics of drugs and likely account for the unexplained interindividual variability in drug response. These findings provide evidence of the utility of WES for pharmacogenomic testing and into clinical practice.

Update of Takotsubo cardiomyopathy: Present experience and outlook for the future

Takotsubo cardiomyopathy (TTS) has become a recognised clinical entity since the Japanese scientist Sato first described it in 1990. Despite an increasing number of confirmed cases, especially during the COVID-19 pandemic, its pathophysiology remains incompletely understood, and decision-making differs in the diagnosis and treatment. In addition, it is not evident whether a significant increase in TTS is due to better understanding among practitioners and widespread access to coronary angiography, or if it is a reflection of an actual increase in incidence. We analysed a series of international research studies from 1990 to 2021. Beyond epidemiology and clinical presentation, we evaluated and summarised fundamental knowledge about various predisposing factors, with particular attention to the iatrogenic impact of certain drugs, namely antidepressants, chemotherapy, and antiarrhythmics. Furthermore, we highlighted the main pathophysiological theories to date. In addition, based on published studies and clinical cases, we investigated the role of numerous diagnostic approaches in the differential diagnosis of TTS and identified predictors of TTS complications, such as cardiogenic shock, ventricular fibrillation, and left ventricular thrombi. Accordingly, we sought to propose a diagnostic algorithm and further treatment management of TTS under the presence of possible complications to help practitioners make more informed decisions, as the initial presentation continues to pose a challenge due to its close similarity to acute coronary syndrome with ST-elevation. In conclusion, this article examines Takotsubo cardiomyopathy from different perspectives and, along with future systematic reviews and meta-analyses, can be of particular interest to practising cardiologists and researchers in developing clinical guidelines.

Cardiotoxicity of Fluoropyrimidines: Epidemiology, Mechanisms, Diagnosis, and Management

Cancer is a growing public health problem; it is responsible annually for millions of deaths worldwide. Fluoropyrimidines are highly effective and commonly prescribed anti-neoplastic drugs used in a wide range of chemotherapy regimens against several types of malignancies. 5-fluorouracil and its prodrugs affect neoplastic cells in multiple ways by impairing their proliferation, principally through the inhibition of thymidylate synthase. Fluoropyrimidine-induced cardiotoxicity was described more than 50 years ago, but many details such as incidence, mechanisms, and treatment are unclear and remain disputed. Severe cardiotoxicity is not only life-threatening, but also leads to withdrawal from an optimal chemotherapy regimen and decreases survival rate. Differences in the frequency of cardiotoxicity are explained by different chemotherapy schedules, doses, criteria, and populations. Proposed pathophysiological mechanisms include coronary vasospasm, endothelial damage, oxidative stress, Krebs cycle disturbances, and toxic metabolites. Such varied pathophysiology of the cardiotoxicity phenomenon makes prevention and treatment more difficult. Cardiovascular disturbances, including chest pain, arrhythmias, and myocardial infarction, are among the most common side effects of this class of anti-neoplastic medication. This study aims to summarize the available data on fluoropyrimidine cardiotoxicity with respect to symptoms, incidence, metabolism, pathophysiological mechanism, diagnosis, management, and resistance.

Fluoropyrimidine-induced cardiotoxicity

Cardio-oncology is a discipline based on early screening, monitoring, and treating chemotherapy-induced cardiotoxicity. There are many chemotherapeutics known for their cardiac toxic effects, including fluoropyrimidines. Fluoropyrimidine represents the cornerstone of many types of cancer and each year almost two million cancer patients undergo this treatment. Fluoropyrimidine-induced cardiotoxicity can be manifested in several forms, from angina pectoris to sudden death. This paper is a review of how the cardiotoxicity of fluoropyrimidines is presented, the mechanisms of its occurrence, its diagnosis, and management.

Alternative Treatment Options in Patients with Colorectal Cancer Who Encounter Fluoropyrimidine-Induced Cardiotoxicity

5-Fluorouracil (5-FU) remains to be the backbone of chemotherapy regimens approved for treatment of colorectal cancer and other gastrointestinal cancers and breast cancer. The incidence of cardiotoxicity associated with 5-FU ranges from 1.5-18%. Previous studies also concluded that rechallenging a patient with previous 5-FU cardiotoxicity with either lower dose or another mode of administration could result in repeat of cardiac complication in up to 45% of patients. Nearly 13% of patients died upon re-exposure to 5-FU. Clinical manifestations of cardiac complications of fluoropyrimidines including angina, myocardial infarction, arrhythmias, hypotension, Tako-Tsubo syndrome, heart failure, cardiogenic shock, pericarditis, and even sudden death have been reported. Cardiotoxicity is unpredictable and no alternative chemotherapeutics have been defined so far. The author describes here treatment options for patients with metastatic colorectal cancer who have encountered fluoropyrimidine-induced cardiotoxicity, including switching to a different fluoropyrimidine, switching to a different schedule of intravenous 5-FU, or switching to a non-fluoropyrimidine-containing chemotherapy regimen if one exists. Switching to a non-fluoropyrimidine-containing chemotherapy regimen is usually the most feasible choice for patients with metastatic disease as data on adjuvant setting is usually a fluoropyrimidine or its combination with oxaliplatin at present.

Safety and Efficacy of s-MOX Regimen in Patients with Colorectal Cancer Who Developed Cardiotoxicity Following Fluoropyrimidine Administration: A Case Series

BACKGROUND

Fluoropyrimidines compose the backbone of regimens to treat many common solid tumors, including gastrointestinal (GI), breast and head/neck. As we continue to use these agents routinely, recognition of rare but real toxicities, such as cardiotoxicity, has also improved. The treatment options for patients who have encountered fluoropyrimidine-induced cardiotoxicity are limited as many anti-angiogenic drugs also pose a cardiac risk.

PATIENTS AND METHODS

We present a case series of three patients who developed cardiotoxicity in the form of anginal-like symptoms, EKG changes and elevated cardiac enzymes on infusional 5-FU or capecitabine and were subsequently treated with the s-MOX (simplified-mitomycin-oxaliplatin) regimen for their metastatic colorectal cancer (mCRC). All three patients were tested for polymorphic abnormality of DYPD and TYMS.

RESULTS

All three patients were treated with s-MOX consisting of mitomycin-C 7 mg/m² on day 1 and oxaliplatin 85 mg/m² on days 1 and 15 (1 cycle = 28 days) after they encountered cardiotoxicity to 5-FU and/or capecitabine. None of these patients developed any cardiotoxicity on s-MOX. Overall, the MOX regimen was well tolerated. The most common toxicities included ≤ 2 grade peripheral neuropathy, nausea, vomiting, thrombocytopenia, and anemia. Grade ≥ 3 toxicities included neutropenia (10%), thrombocytopenia (33%), vomiting (8%), and peripheral neuropathy (30%). DYPD gene was normal in all patients and TYMS was abnormal (2R/2R) in one patient.

CONCLUSION

This is the first case series that reports the safety and feasibility of s-MOX in patients with mCRC who developed cardiac toxicity to 5-FU or capecitabine. The s-MOX regimen may provide an alternative treatment option for patients who either develop fluoropyrimidine-related cardiotoxicity or who have abnormalities in the DYPD gene.

Outcomes of Takotsubo cardiomyopathy in hospitalized cancer patients

BACKGROUND

Chemotherapy-induced cardiomyopathy is a critical complication of treatment for cancer. The emotional stress of a cancer diagnosis, ongoing chemotherapy, abnormal cancer-related wasting syndrome may contribute to cardiac morbidity in these patients. The burden of Takotsubo Cardiomyopathy (TCM) in cancer patients is unknown. The incidence of TCM and related outcomes in cancer patients was investigated in this study.

METHODS

The 2007-2013 National Inpatient Sample (NIS) was analyzed for patients with a prior and new diagnosis of TCM with and without malignancy. Risk factors for mortality were adjusted for associated conditions by multivariable logistic regression analysis.

RESULTS

From 2007 to 2013, an estimated 122,855 adults were admitted with a diagnosis of TCM. In 2013, the incidence of admissions in US of patients with coexisting TCM and malignancy was 1.13%. Patients admitted for TCM with coexisting malignancy had a significantly higher mortality (13.8 vs. 2.9%, p < 0.0001), length of stay (7 vs. 4 days, p < 0.0001) and total charges ($29,291 vs. $36,231, p < 0.0001), compared to those with no malignancy. In patients with a primary diagnosis of TCM and without any underlying malignancy, males had a higher mortality (4.02 vs. 1.03%, p < 0.0001), whereas there was no gender difference in mortality in those with coexisting malignancy (6.25 vs. 6.45%, p = 0.965). On multivariable logistic regression analysis, risk factors associated with mortality were solid cancer (OR 3.43, p = 0.008), stroke (OR 18.33, p < 0.0001) and heart failure (OR 1.918, p = 0.004).

CONCLUSIONS

Outcomes are significantly worse in patients with TCM and malignancy. Hence, this patient population must be regarded as high-risk and early diagnostic consideration for TCM is warranted. Early intervention may help lower mortality, decrease resource utilization and reduce the health care costs in these patients.