Cardiotoxicity Associated with Gemcitabine: Literature Review and a Pharmacovigilance Study

Background: Gemcitabine is a nucleoside analog, widely used either alone or in combination, for the treatment of multiple cancers. However, gemcitabine may also be associated with cardiovascular adverse-drug-reactions (CV-ADR). Methods: First, we searched for all cases of cardiotoxicity associated with gemcitabine, published in MEDLINE on 30 May 2019. Then, we used VigiBase, the World Health Organization’s global database of individual case safety reports, to compare CV-ADR reporting associated with gemcitabine against the full database between inception and 1 April 2019. We used the information component (IC), an indicator value for disproportionate Bayesian reporting. A positive lower end of the 95% credibility interval for the IC (IC025) ≥ 0, is deemed significant. Results: In VigiBase, 46,898 reports were associated with gemcitabine on a total of 18,908,940 in the full database. Gemcitabine was associated with higher reporting for myocardial ischemia (MI, n: 119), pericardial diseases (n: 164), supraventricular arrhythmias (SVA, n: 308) and heart failure (HF, n: 484) versus full database with IC025 ranging between 0.40 and 2.81. CV-ADR were associated with cardiovascular death in up to 17% of cases. Conclusion: Treatment with gemcitabine is associated with potentially lethal CV-ADRs, including MI, pericardial diseases, SVA and HF. These events should be considered in patient care and clinical trial design.


Introduction
Gemcitabine is a cytidine analog that incorporates into DNA and terminates chain elongation by inhibiting ribonucleotide reductase and DNA repair [1]. It is still widely used, either alone or in combination to treat various cancers including lung, pancreas, bladder, breast, ovary and bile duct carcinomas, lymphomas and uterine sarcomas [2]. Gemcitabine is generally preferred in elderly or fragile patients due to lower toxicity profile compared to other anticancer drugs. While myelosuppression is the most commonly observed adverse drug reaction (ADR) associated with this molecule, several other ADRs have emerged since gemcitabine was approved by the Food and Drug Administration (FDA) [2], including thrombotic microangiopathy [3], interstitial pneumonitis [4] and capillary leak syndrome (CLS) [5].
According to the FDA label, incidence of cardiovascular ADR (CV-ADR) associated with gemcitabine is low and rarely leads to drug discontinuation [2]. The European Medicines Agency also notifies the particular caution with patients presenting a history of cardiovascular events due to the risk of CV-ADR with gemcitabine [6].
We identified three patients in Saint-Antoine and Pitié-Salpêtrière hospitals (Paris, France) who developed a CV-ADR suspected to be related to gemcitabine. They presented with pancreatic cancer and CV-ADR were pericardial effusion associated with heart failure in two of them, which occurred 6 to 8 months after gemcitabine initiation. Partial or complete recovery was observed after instauration of heart failure therapeutics (see details of in Table 1). One patient presented its pericardial effusion as part of a CLS recovered after glucocorticosteroids administration (Supplementary Figure S1 and Videos S1-S3 present dynamics of his recovery).
Herein, we aim to further delineate the overall spectrum of CV-ADR associated with gemcitabine. First, we present three news cases of cardiotoxicity associated with gemcitabine (Table 1) and their management (i), we perform a literature review focusing on the description of CV-ADR reported on gemcitabine in MEDLINE (ii) and (iii) we use VigiBase, the WHO's international pharmacovigilance database of individual case safety reports (reports, thereafter) to describe the reported CV-ADR cases associated with gemcitabine.
Moreover, among the 106 randomized clinical trials evaluating gemcitabine as monotherapy (overall number of patients = 14015), 17 trials (n = 2386) had reports for at least one CV-ADR in the published work (Supplementary Figure S2 for the flow chart of selected trials). In these latter 17 trials, 33 CV-ADR were reported, leading to an estimate of CV-ADR incidence rate on gemcitabine monotherapy ranging from 0.24% (33/14015) to 1.38% (33/2386), varying with the denominator considered. Quality of CV-ADR reporting in these trials, mostly from decades ago was too low to make sure that all CV-ADR events were effectively captured and reported in the publication. These events were severe in n: 27/33 (82%) (n: 14/33 grade 3/4 and n: 13/33 death), and included 8 MI, 2 pericardial effusions, 7 HF and 1 arrhythmia ( Table 2). Table 2. Cardiovascular adverse drug reactions in randomized clinical trials evaluating gemcitabine in monotherapy with at least one report for cardiovascular adverse-drug-reactions (CV-ADR).

Study
Type of Study

Discussion
We report the first large-scale analysis associating specific CV-ADR with gemcitabine. This study of individualized reportable events from the WHO pharmacovigilance database combined with the literature review allowed us to better characterize the CV-ADR associated with gemcitabine, notably the clinical characteristics including time to onset and severity of approximatively 1000 reports with gemcitabine-associated cardiotoxicity, versus few isolated case reports published previously (Table 1).
Gemcitabine was associated with MI, SVA, HF and pericardial diseases. The same cardiotoxicity signals from gemcitabine have also been reported in clinical trials. Aapro et al. pooled 979 patients treated by gemcitabine in 22 phase-2 trials and showed that incidence of MI, HF, arrhythmias and pericarditis were 0.5%, 0.4%, 0.2% and 0.1%, respectively [38]. Our meta-proportion analysis of randomized clinical trials evaluating gemcitabine as monotherapy showed similar incidence estimates of~1% for overall CV-ADR including MI, SVA, HF and pericardial diseases. We showed that mortality associated with these CV-ADRs ranged from 3% for after pericardial diseases versus 17% for after MI and HF. Severity including death and grade 3/4 events reported in randomized clinical studies (82%) was similar to that of the pharmacovigilance reports (87%). Though, it has to be noted that the quality of CV-ADR adjudication in the trials considered in our analysis was low precluding the possibility of precisely characterizing these CV-ADR. Pericardial diseases had the strongest association with gemcitabine administration (highest IC 025 , Table 3), and were presented as cardiac tamponade (28/164, 17%) or constrictive pericarditis (6/164, 4%). Noteworthily, pericardial disorders could be part of CLS, a systemic disease determined by vascular protein leakage and diffuse serosa effusions requiring specific management, including glucocorticoids [39][40][41]. Association between gemcitabine and CLS using VigiBase have been described previously [5].
Although CV-ADRs were severe, required hospitalization and often were not fully reversible, cardiac toxicity of gemcitabine is not well known to clinicians. Even in the absence of cardiovascular risk factors, cardiotoxicity related to gemcitabine should be immediately suspected in the case of breathlessness, palpitations, or chest discomfort. Moreover, cardiovascular screening (e.g., echocardiography assessing pericardium and left ventricular ejection fraction, past cardiac history and prior radiation therapy) may identify patients at higher risks of gemcitabine-associated cardiotoxicity but this strategy needs to be evaluated in a dedicated study. Furthermore, in some case-reports (Table 1), gemcitabine re-challenge led to recurrence of the CV-ADR suggesting that decision to restart gemcitabine needs to be weighted between cardiotoxicity and anti-tumor efficacy [42].
Several hypotheses are suggested to explain association of gemcitabine with the various CV-ADRs, but no thorough preclinical mechanistic study is available. Similar to fluoropyrimidines (other antimetabolites), vasospasm has been proposed to be responsible for gemcitabine-associated MI [7][8][9]. Interestingly, MI associated with gemcitabine were often co-reported with strokes in our study, suggesting that shared cardiovascular risk factors and/or a shared pathophysiological mechanisms (i.e., arterial vasospasm) may play a role. For pericarditis, Vogl et al. highlighted for the first time an association between gemcitabine and pericarditis via a radiation recall reaction (acute inflammatory reaction confined to previously irradiated areas triggered when chemotherapy agents are administered) [19]. The recalled inflammation induced by gemcitabine may lead to fluid accumulation in the incompliant pericardial space and ultimately tamponade [43]. Consistently with this hypothesis, we found an association between radiation recall reaction and pericardial diseases. However, prior irradiation was not mandatory for gemcitabine induced pericardial effusion (3 with no prior irradiation among 8 cases with gemcitabine pericarditis, Table 1). For HF, a retrospective study suggested diabetes, coronary artery disease and a total gemcitabine dose >17.000 mg/m 2 as risk factors for developing gemcitabine-induced HF but validity of results are limited by a small sample size (7 HF on a total of 156 gemcitabine treated patients) [44]. In VigiBase, we were unable to obtain cumulative doses of gemcitabine but our data showed increased time to onset and increased duration of gemcitabine treatment for HF vs. other CV-ADRs patients, further supporting this cumulative dose effect. Notably, we found that specific concomitant intake of anticancer drugs on top of gemcitabine were more likely to be associated with different type of cardiotoxicities such as platins with MI, HER-2 blockers with HF, and immune checkpoint inhibitors with pericardial disorders. Indeed, these drugs are known to induce these conditions and the hypothesis of toxic synergy or multiple hit mechanisms with these combinations is likely [18,45,46]. Overall, the co-administration of drugs that can induce CV-ADR should strengthen the surveillance of high-risk cardiovascular patients receiving combination of such agents.
We acknowledge several limitations of VigiBase pharmacovigilance analysis, the first of which is under-reporting of suspected CV-ADRs. While the accurate magnitude of underreporting cannot be computed, estimates vary up to 90% of the actual adverse events not being reported [47,48]. However, VigiBase is a worldwide database, gathering data from over 130 countries and with almost 1000 CV-ADR reports related to gemcitabine vs. few case-reports previously described. Sources of reports are non-homogeneous with limited possibility for verification of the clinical, laboratory tests, or radiological findings and re-assessment of the causality of the drug-ADR combination. Thus, in approximately two-third of reports, gemcitabine was the only suspected drug for the reported cardiotoxicity. The exact denominator of patients exposed to gemcitabine cannot be evaluated precluding estimation of incidence of these CV-ADRs using VigiBase. Instead, total number of reports for the studied drug is used as denominator for this kind of analysis [45]. The value of disproportionality analysis for CV-ADR associated with anticancer drugs has already been shown in various settings with confirmation of signals by prospective trials or basic mechanistic studies, such as with myocarditis induced by immune-checkpoint inhibitors, or QT prolongation induced by anti-hormones but nevertheless, there is still a risk that results from pharmacovigilance databases might be misleading [45,49,50]. Yet, these above-described CV-ADRs associated with gemcitabine must warrant caution.

Literature Review
We performed a systematic search on PubMed (MEDLINE) using the terms "Cardiotoxicity AND Gemcitabine" with no filter, at the date of 30 May 2019.Then, we screened the bibliography of selected publications. We identified a total of 18 publications including case-reports between 1999 and 2018 focusing on gemcitabine cardiotoxicity. We also performed a systematic search on Pubmed (MEDLINE) for randomized clinical trials using the term "gemcitabine" up to 30 September 2020 and found 958 manuscripts. We then selected articles evaluating gemcitabine monotherapy in at least one of the treatment arms and found 106 studies (Supplementary Figure S2).

Study Design and Data Sources
This observational, retrospective, pharmacovigilance study is based on ADR reported in deduplicated VigiBase, the WHO's international database of individual case safety reports (ICSRs, or reports in the text) which includes reports from over 130 countries [51]. These reports originate from different sources, such as healthcare professionals, patients, and pharmaceutical companies, and are generally notified post-marketing. The use of confidential, electronically processed patient data was approved by the French National Commission for Data Protection and Liberties (reference number #1922081). It was not appropriate or possible to involve patients or the public in the design, or conduct, or reporting, or dissemination plans of our research. ClinicalTrials. CV-ADR specifically assessed in the analysis were those notified as suspected to be induced by gemcitabine. Each report contains general administrative information (country, date, and reporter qualification), patient characteristics (sex and age), drugs (indication, start and end dates), and reactions (onset and end date, seriousness, outcome).

Statistical Analysis
VigiBase allows for disproportionality analysis (also known as case-non-case analysis), which we used to assess whether suspected drug-induced CV-ADR were differentially reported with gemcitabine versus the full database. Disproportionality analysis compares the proportion of selected specific ADR (e.g., pericarditis) reported for a single drug (e.g., gemcitabine) with the proportion of the same ADR for a control group of drugs (e.g., full database). The denominator in these analyses is the total number of ADR reported for each group of drugs. If the proportion of ADR is greater in patients exposed to a specific drug (cases) than in patients not exposed to this drug (non-cases), then an association can be made between the specific drug and the reaction leading to a potential safety concern. Disproportionality in VigiBase is generally calculated using the information component (IC), an indicator value for disproportionate Bayesian reporting when using the full database as comparator [45]. Disproportionality can also be calculated by using a frequentist disproportionality estimate, i.e., the reporting odds ratio (ROR) [49,53].
Calculation of the IC using a Bayesian confidence propagation neural network was developed and validated by the Uppsala Monitoring Centre (organism managing VigiBase) as a flexible, automated indicator value for disproportionate reporting that compares observed and expected drug-ADR associations to find new drug-ADR signals with identification of probability difference from the background data (full database) [54]. Probabilistic reasoning in intelligent systems (information theory) has proved to be effective for the management of large datasets, is robust in handling incomplete data, and can be used with complex variables [54]. Several examples of validation with the IC exist, showing the power of the technique to find signals soon after drug approval by a regulatory agency (e.g., an association between captopril and coughing), and to avoid false positives, whereby an association between a common drug and a common ADR occurs in the database only because the drug is widely used and the ADR is frequently reported (e.g., between digoxin and rash) [54,55].
The statistical formula is as follows: Nexpected is the number of ICSRs expected for the drug-ADR combination. Nobserved is the actual number of ICSRs for the drug-ADR combination. Ndrug is the number of ICSRs for the drug, regardless of ADR. Neffect is the number of ICSRs for the ADR, regardless of drug. Ntotal is the total number of case reports in the database. IC 025 is the lower end of a 95% credibility interval for the IC. A positive IC 025 value (>0) is the traditional threshold deemed significant [45,54,55]. Characteristics of cases were described in terms of means (standard deviation, SD) or medians (interquartile range, IQR) for quantitative variables, and in terms of numbers and proportion for qualitative ones. Unpaired Student t-tests were performed to compare means of two groups and analysis of variance (ANOVA) or Kruskal-Wallis test was used to compare means or medians of more than two groups, respectively. χ 2 -tests were performed for comparisons of qualitative variables.

Conclusions
In conclusion, this international global pharmacovigilance study showed that gemcitabine is significantly associated with an over-reporting versus full database of drug-induced myocardial ischemia, pericardial diseases, supraventricular arrhythmias and heart failure with almost one thousand cases and moderate overlap between these conditions (0-20%). These conditions were described rarely in the past literature, with only 20 case-reports. Pericardial effusion associated with gemcitabine were eventually part of a capillary leak syndrome, a systemic condition responsive to glucocorticoids. These cardiovascular adverse events remained rare (incidence~≤ 1%) and generally occurred within 1-2 months of gemcitabine start, except heart failure adverse events which occurred later and showed less reversibility (30% sequalae or no recovery). Subsequent cardiovascular death occurring in 3-17% of case, emphasizing their seriousness. Hence, cardiotoxicities related to gemcitabine are potentially life-threatening should be investigated in patients care and clinical trials design, particularly in combination with other cardiotoxic drugs.
Supplementary Materials: The following are available online at http://www.mdpi.com/1424-8247/13/10/325/s1, Figure S1: Summary of one of our case-report presenting a capillary leak syndrome associated with gemcitabine reversible after glucocorticoids, Figure S2: Flowchart of selected studies to describe cardiovascular adverse events associated with gemcitabine, Figure S3: UpsetR graph representing overlap between cardiovascular sub-classifications, Table S1: Concurrent adverse events in individual case safety reports of gemcitabine-associated cardiovascular adverse drug reactions (CV-ADRs) in VigiBase, Video S1: Echocardiography at admission, Video S2: Echocardiography at day 5, Video S3: Echocardiography at admission at day 10.